This is Dr Kiran welcoming all to the new post of NH blog. I would like to know the usefulness of the segment on current evidences. I understand that it is quite dry and interspersed with so many strange-looking names and studies. But, that is how the evidence based analysis look like! Probably, this is one segment in medical practice which needs cosmetic lift-up to get better mass appeal!
This post, I am gathering evidence on the ‘Use of Sildenafil in post-op states in CHD’. This would be followed by our regular features on learning scenarios and Pearls.
Let us start with the evidence basis for ‘Use of Oral Sildenafil in Pediatric Patients with Congenital Heart Disease in post-operative setting’.
The current use of oral sildenafil in Pediatric population is largely an extrapolation of adult studies pertaining to pulmonary hypertension. However, the comparison is not that straight forward. The possible hemodynamic variants associated with congenital heart diseases are extensive. CHD may have absence of a crucial pulmonary valve, may come with serial and parallel circulations, pulmonary hypertension of high flow against high resistance, ala-carte designed surgical states to suit the anatomy and so on. So, unless the fundamentals are understood well, it may not be appropriate to use sildenafil as a knee-jerk response. Adding to the woes, there are no clearly definable outcome parameters to define the efficacy and results with treatment of sildenafil in the immediate post-op states.
Q1. Is sildenafil therapy logical in post-op CHD status?
In 1993, Celermajer et al showed that there is pre-existing pulmonary endothelial dysfunction caused by preoperative high flow pulmonary hemodynamics, which may alter the course in post-op states. In their article titled ‘Impairment of endothelium-dependent pulmonary artery relaxation in children with congenital heart disease and abnormal pulmonary hemodynamics’ in the journal Circulation, they discussed this issue extensively. The same point was proved with simian experiments by Glavind-Kristensen in 2002 for post bypass status. Their article titled ‘Pulmonary endothelial dysfunction after cardiopulmonary bypass in neonatal pigs’ was published in Acta Anaesthesiology Scandinavia. In the same year, Lindberg et al published their article ‘How common is severe pulmonary hypertension after pediatric cardiac surgery?’ in JTCS. They found that iNO therapy is frequently indicated for the stabilization of pulmonary vascular reactivity, and decreased incidence of postoperative pulmonary hypertensive crisis. However, abrupt discontinuation of iNO was a major problem. In 1996 Atz et al had written on ‘Rebound pulmonary hypertension after inhalation of nitric oxide’ in ATS. Hence, there was a need for another treatment modality to prevent rebound PHT caused by abrupt discontinuation of iNO in post-extubation period. In 1999, Jackson et al showed the ‘Effects of sildenafil citrate on human hemodynamics’ in AJC. This was followed by another article by Atz et al titled ‘Sildenafil ameliorates effects of inhaled nitric oxide withdrawal’ in the journal Anesthesiology in the same year.
Q2. Is the supposed efficacy of Sildenafil proven?
In 2005, Karatza et al published the first study of Sildenafil in children in International journal of Cardiology, titled ‘Safety and efficacy of sildenafil therapy in children with pulmonary hypertension’. Here, they compared the efficacy and pharmacokinetics of Sildenafil with adult population as control and found equal efficacy. In 2007, in an article titled ‘Effects of escalating doses of sildenafil on hemodynamics and gas exchange in children with pulmonary hypertension and congenital cardiac defects’, Raja et al showed the efficacy of Sildenafil in the post-op CHD states by noticing a significant decrease in PA pressure compared with baseline values after starting sildenafil, without changes in CVP and systemic arterial pressure. In the same year, Peiravian et al published ‘Oral sildenafil to control pulmonary hypertension after congenital heart surgery’ in Asian Cardiovascular and Thoracic Annals. Here, they demonstrated the use of Sildenafil in post biventricular repair.
Q3. Is there a role of Sildenafil in Post-Fontan surgery?
Khambadkone et al in 2003 published ‘Basal pulmonary vascular resistance and nitric oxide responsiveness late after Fontan-type operation’ in the journal Circulation. They showed that PA pulsatility is crucial for endothelium-dependent pulmonary vasodilation. However, Fontan circulation takes away the PA pulsatility. In 2008, Rossi et al showed that ‘Sildenafil improves endothelial function in patients with pulmonary Hypertension’ in an article published in Pulmonary Pharmacology and Therapeutics. This finding extrapolated that any patient with Fontan procedure is likely to benefit from Sildenafil. Apart from this, in 2008 Giardini et al showed ‘Effects of silenafil on haemodynamic response to exercise and exercise capacity in Fontan patients’ in European Heart Journal, demonstrating the improvements found in the hemodynamic profiles in post-Fontan patients on Sildenafil. Earlier in 2006, Haseyama et al in JTCS had shown ‘Pulmonary vasodilation therapy with sildenafil citrate in a patient with plastic bronchitis after the Fontan procedure for hypoplastic left heart syndrome’ where they demonstrated an improvement in the plastic bronchitis. In the same year in ATS, Uzun et al had shown ‘Resolution of protein-losing enteropathy and normalization of mesenteric Doppler flow with sildenafil after Fontan’. However, it is well understood that in patients with Fontan procedure, improvement of tissue oxygenation and hemodynamic parameters are more important than mean PA Pressure decrement.
Overall, it can be concluded that, in the present level of evidence, Sildenafil can be used safely in postoperative pediatric patients with CHD. It appears to be effective, or at least protective, against rebound PHT caused by withdrawal of iNO.
With this, let us get back to our regular feature: interesting learning scenarios:
ACUTE SEVERE AND CHRONIC
In acutely compromised hearts, is better to accept a natural deterioration or to go on a high-risk endeavour? We had a 10-year-old with acute deterioration of a chronic MR with a very vague history. Although her LV function could be pepped up with inotropic support, her third spacing was enormous. She had bilateral massive pleural effusions, ascitis and trace pericardial effusion. Left alone, we felt she may not get any better with medical management. However, the surgical risks are multiple-fold high in such patients. The only saving grace was preserved LV function, which could give some hope to patient and surgeon! It was contemplated that the existing third spacing is likely to add on to the post-op woes. One suggestion was to use peritoneal dialysis for about 72 hours and slowly decongest the accumulations. This would presumably reduce the myocardial edema and improve contractility. However, this idea was not considered effective by the entire team. The questions are: Is the venturing into high risk surgery in such cases advisable? Should more time be spent on medical management? Is PD a choice for consideration? Please let me know your opinions.
ONE AV, TWO SEMILUNARS
Is there a situation in left heart which parallels tricuspid atresia 3C? We had an infant diagnosed as TAPVC from outside. However, on echo, we found an obstructed cardiac TAPVC with a barely visible LA cavity. The mitral valve was imperforate. The LV was smallish, fed only by a couple of muscular VSDs shunting R to L. The RA and RV were dilated. The LV gave rise to reasonable sized aorta (Z score of minus 1) and RV to well developed, dialted PA. The ascending and transverse aortae were normal sized. The baby was symptomatic largely due to obstructed TAPVC and unusually increased Qp. One of the possibilities we thought was repair of TAPVC, DKS with BT shunt. With aortic valve being reasonable, is there any other possibility? What would the natural history of VSDs in such situations? Please let me know your ideas on the management of such issues.
JUXTADUCT
This one has always remained elusive. I don’t know if I have discussed this issue earlier. It becomes very difficult to assess the status of coarctation in the presence of patent arterial duct. We had a 4-year-old who had undergone a balloon coarctoplasty in an outside hospital in her infancy. She was being followed up. When she came to us, we found a moderately restricted PDA with a narrow juxtaductal segment. There was only systolic gradient across the narrow segment with no diastolic spillage. The classical teaching is that the presence of duct interferes with evaluation of coarctation. In this instance, we are not sure of the significance of coarctation. There were no systemic clinical signs of CoA. We contemplated the unmasking of CoA once the duct is closed. The CT may help us in this issue by a 3D reconstruction. Even if there is no CoA on CT at baseline, would the large aortic disc of PDA device compromise the diameter of juxtaductal segment further, thereby creating a CoA? I felt it is better to subject the patient for surgical ligation of PDA. We can always check for the CoA after PDA ligation on table and take a call. What is the advice of readership? How would you like to tackle this case? Please let all know.
DILATED PA
We recently had a 25-year-old referred for abnormal Chest radiograph from outside. She was otherwise asymptomatic. On examination, there was a click in the pulmonary area. Echo showed doming pulmonary valve leaflets with no gradient across. The MPA was significantly dilated. The estimated PA pressures were normal. How far are these pictures common? How frequently should such patients undergo repeat evaluations and what to look for? Is there a management plan for them? Is the supposed progress preventable by medications? There appears to be lot of data on bicuspid aortic valves. However, no such data seems to exist for this category. If anyone has any such instances in their follow up, please let us know.
SEPTOSTOMY Vs BTT SHUNT
This issue probably needs much more discussion in the professional circles. I have brought up this issue in the previous posts too. When it comes to mixing lesions, the capacitance chambers are much superior to contracting ones. That is the reason why a moderate sized ASD proves to be a superior option than a large VSD in TGAs. When a TGA with restrictive ASD gets desaturated, adding BTT shunt does no good. In fact, it may worsen the scenario. Extending the logic, this should be true for any d-malposed great artery situations, unless it is DILV! I came across one 11-year-old with 100% DORV saturating 56%. The PS was mild and the PAs were dilated. There was a subarterial VSD of about 40% of aortic annulus with a PFO. In this case, even the best of streaming cannot deliver a good amount of oxygenated blood into Aorta. How different the scenario is if there were to be a non-restrictive ASD? Please let me know your opinions on this.
PEDIATRIC CARDIOLOGY PEARLS
111. Neonates are more resilient to metabolic or ischemic injury. In fact, the neonate may be particularly capable of coping with some forms of stress. Tolerance of hypoxia in the neonate is characteristic of many species, and the plasticity of the neurologic system in the newborn is well described. (Lenn NJ. Plasticity and responses of the immature nervous system to injury. In journal Seminars in Perinatology in the year 1987 page 117)
112. The physiology of the PDA is secondary to overperfusion of the lung and possibly underperfusion of the systemic circulation. Infants' lungs are fully recruited at rest so that any increase in flow from left-to-right shunts predictably increases fluid filtration in the lung. (Alpan G, Scheerer R, Bland R, et al. Patent ductus arteriosus increases lung fluid filtration in preterm lambs. In journal Pediatric Research in the year 1991 page 616)
113. Elevated transpulmonary pressure gradient and elevated pulmonary vascular resistance have been identified as risk factors for early mortality after heart transplantation. (Kirklin JK, Naftel DC, Kirklin JW, et al. Pulmonary vascular resistance and the risk of heart transplantation. In Journal of Heart Transplantation in the year 1988 page 331)
114. Catheter therapy has now been applied to the cure or modification of most pediatric arrhythmias, including AV node re-entry tachycardia, ectopic atrial tachycardia, atrial re-entry/flutter, congenital junctional ectopic tachycardia, and some forms of ventricular tachycardia. (Kugler JD, Danford DA, Deal BJ, et al. Radiofrequency catheter ablation for tachyarrhythmias in children and adolescents. The Pediatric Electrophysiology Society. In New England Journal of Medicine in the year 1994 page 1481)
115. A release of nickel from the device with a peak at 1 month postimplantation has been described. However, its clinical significance is questionable, and reports of clinically significant allergic reactions to nickel after device implantation are rare. (Lai DW, Saver JL, Araujo JA, et al. Pericarditis associated with nickel hypersensitivity to the Amplatzer occluder device: A case report. In journal Catheterization and Cardiovascular Interventions in the year 2005 page 424)
This brings us to the end of another post. Please send your comments and suggestions to drkiranvs@gmail.com Hoping to add some features on to the existing segments. Please suggest if any novel ideas occur!
Regards
Kiran
ಭಾನುವಾರ, ನವೆಂಬರ್ 28, 2010
ಬುಧವಾರ, ನವೆಂಬರ್ 17, 2010
Dr Kiran welcomes all to the new post of NH blog. As previous, we shall see a review on the current controversies, few learning scenarios and the pearls. Thanks for the feedback on the section on controversies and hope to continue. Please suggest topics of interest from your side too.
In this post, we will see the current evidence on the use of antiplatelet agents in pediatric practice with special emphasis on cardiac patients.
Q1. What are the currently available antiplatelet agents for pediatric use?
1. Aspirin: inhibits platelet function by irreversibly binding to cyclooxygenase (COX)-1
2. Dipyridamole: inhibits adenosine uptake into platelets
3. Clopidogrel: irreversibly binds to the purinergic P2Y12 receptor on platelets
4. Intravenous GP 2b/3a inhibitors abciximab, eptifibatide, and tirofiban: bind to platelet GP 2b/3a receptors, which prevents their cross-linking with fibrinogen and blocks the last common pathway of platelet aggregation
Q2: Why is antiplatelet therapy for children different from adults?
Two separate studies by Rajasekhar and collegues discussed the differences in the functional activities of platelets in newborns and that from adult population. The first was during 1994, in an article titled ‘Neonatal platelets are less reactive than adult platelets to physiological agonists in whole blood’ in the journal Thrombosis and Haemostasis. This was followed by an article in the same journal in 1997 titled ‘Platelet hyporeactivity in very-low-birth-weight neonates’. Israles and colleagues published their data in 2001 in the Journal of Pediatrics. The article was titled ‘Evaluation of primary hemostasis in neonates with a new in vitro platelet function analyzer’ which showed a decreased platelet functional response in neonates than adults. These findings suggested that neonates may require lower weight-adjusted doses of antiplatelet agents to achieve the same level of platelet inhibition as for adults and older children.
Apart from the physiological differences, some practical problems are also observed. The children are more mobile and more likely to fall and injure themselves. This is added on with their lesser degree of understanding and adherence to instructions. Reye’s syndrome is a potential complication. Also, they are less likely to understand the consequences of stopping the therapy or not adhering to the dosage.
Q3: What are the present cardiac interventional indications for antiplatelet therapy in children?
The present cardiac indications would be children who undergo implantation of cardiac devices (such as ventricular assist devices (VADs), septal defect occluders, and stents)
An expert review was published in 2008 by Fu and Hijazi under the title ‘The Amplatzer Septal Occluder, a transcatheter device for atrial septal defect closure’ where they strongly advocated the use of aspirin post-ASD device closure. They have quoted the famous study by Fischer et al published in journal Heart in 2003 with title ‘Experience with transcatheter closure of secundum atrial septal defects using the Amplatzer septal occluder: a single centre study in 236 consecutive patients’. In this study, aspirin was used in all 236 and just one patient had a neurological event after 4 years, attributable to device. The evidence is thus in favour of aspirin in this setting.
The data on aspirin with stent placement is not enough, largely due to lesser numbers done in pediatric population. In a retrospective review published by Ebeid et al in 1997, of nine patients (four were 18 years old or younger), aspirin therapy was administered for at least 1 year after implantation of balloon-expandable stents for coarctation of the aorta, and no patient showed evidence of thromboembolism after an average follow-up period of 18 months. This was published in JACC under the title ‘Use of balloon expandable stents for coarctation of the aorta: initial results and intermediate-term follow-up’. Kutty and Zahn published their data on use of aspirin after stent placement in pediatric population in 2008 in the journal Catheter and Cardiovascular Interventions under the title ‘Interventional therapy for neonates with critical congenital heart disease’. In the same year, Menon and colleagues published ‘Hybrid intraoperative pulmonary artery stent placement for congenital heart disease’ in the AJC. In this retrospective review, 24 patients (14 of whom younger than 18 years) received aspirin after undergoing hybrid pulmonary artery stent implantation secondary to congenital heart disease and did not demonstrate any episodes of stent thrombosis over a mean follow-up period of 19 months.
Q4: What are the cardiac post-surgical indications for antiplatelet therapy?
Any child who needs a systemic-to-pulmonary artery shunt is at the risk of thrombotic event. The studies quoting uselessness of therapy were very small and underpowered (Al Jubair et al in 1998 in Journal Cardiology in the Young ‘Results of 546 Blalock-Taussig shunts performed in 478 patients, Fenton et al in ATS in 2003 ‘Interim mortality in infants with systemic-to-pulmonary artery shunts’ and so on) the overall data is in favour of using aspirin (Motz et al in 1999 in journal Cardiology in the Young ‘Reduced frequency of occlusion of aortopulmonary shunts in infants receiving aspirin’, Li et al in 2007 in journal Circulation ‘Clinical outcomes of palliative surgery including a systemic-to-pulmonary artery shunt in infants with cyanotic congenital heart disease: Does aspirin make a difference? and so on).
In 2002, Monagle and Karl published their data as ‘Thromboembolic problems after the Fontan operation’ in Seminars in Thoracic and Cardiovascular Surgery. They advocated the use of aspirin, as children a with single-ventricle approach the Fontan procedure, they remain at high risk of thromboembolic complications.
The data on the use of antiplatelet agents and anticoagulation agents in post-Fontan group remains conflicting. Seipelt and co-workers wrote ‘Thromboembolic complications after Fontan procedures: comparison of different therapeutic approaches’ in ATS in 2002. This was a retrospective study investigating 87 survivors of Fontan surgery, the rates of thromboembolic complications were similar for the patients who received aspirin (1.6 events/100 patient-years) and those who received warfarin (1.1 events/100 patient-years) but much higher for those who received no antithrombotic therapy (4.2 events/100 patient-years). The journal Circulation published an abstract by Monagle et al in 2008 presented at AHA meeting. It was a multicentre randomized trial comparing heparin/warfarin versus aspirin as primary thromboprophylaxis for two years after Fontan procedure in 111 children with mean age of 3.8 years. During a 27-month follow-up period, thrombosis occurred for 24% of the heparin and warfarin recipients and 21% of the aspirin recipients (p = 0.47). The rate of major bleeding also was the same (1 event per group). These data suggest that anticoagulation and antiplatelet therapies are similarly safe and effective in preventing thrombosis after Fontan surgery. However, the favour of surgeon still remains with warfarin in large many institutes across the globe.
Q5: Role of clopidogrel
The year 2005 saw a review article by Finkelstein and colleagues on ‘Clopidogreal use in Children’ in the Journal of Pediatrics. This review served as the baseline for further research with clopidogrel. In 2008, Maltz et al published ‘Clopidogrel in a pediatric population: safety and efficacy results from a single center’ in journal Pediatric Cardiology. It was a retrospective analysis of 90 children (median age, 6.7 years) receiving various doses of clopidogrel. It had a favourable safety and tolerability profile because only two children, both of whom also received aspirin, experienced major bleeding. An additional three patients receiving aspirin plus clopidogrel experienced minor bleeding.
The only randomized control study on Clopidogrel hitherto has been published by Li et al in 2008 in journal Circulation. Popularly called the PICOLO trail, the article is titled ‘Dosing of clopidogrel for platelet inhibition in infants and young children: primary results of the Platelet Inhibition in Children On cLOpidogrel trail’. In this, 92 young children aged 0 to 24 months with cardiac disease were randomized to receive placebo or clopidogrel 0.01, 0.10, 0.15, or 0.20 mg/kg/day. Via platelet aggregometry, clopidogrel 0.20 mg/kg/day was identified as the dose that provided a level of platelet inhibition similar to that achieved with 75 mg/day for adults. Notably, none of the patients experienced serious hemorrhagic events, and only four patients (2 in the placebo group and 1 each in the clopidogrel 0.01 and 0.20 mg/kg/day groups) experienced minor bleeding. The results of PICOLO underscore the importance of conducting randomized clinical trials with children, particularly dose-finding studies, because the 0.20-mg/kg/day clopidogrel dose identified in PICOLO is five times lower than the 1-mg/kg/day dose extrapolated from adult studies.
The ongoing CLARINET study may come out with the answers sought after by the pediatric cardiologists. The details of the trail can be accessed at http://clinicaltrials.gov/ct2/show/NCT00396877 The trail is by Sanofi-Aventis and Bristol-Myers Squibb and titled ‘Efficacy and safety of clopidogrel in neonates/infants with systemic to pulmonary artery shunt palliation (CLARINET)’ and is using clopidogrel at a dose of 0.20mg/kg/day.
Q6: What are the current recommendations for the use of antithrombotic therapy in children?
The current guidelines are drawn from the 2008 report by Monagle and others published in journal Chest. It is the 8th edition of American College of Chest Physicians Evidence-Based Clinical Practice Guidelines on Antithrombotic therapy in neonates and children. The following are excerpts from the content:
• For children with mechanical prosthetic valves who experience thrombotic events while receiving Vit K Antagonist therapy or who cannot tolerate Vit K Antagonist therapy, ASA should be used (Grade 2C)
• Antiplatelet therapy, either ASA (1–5 mg/kg/day) or Dipyridamole (3–10 mg/kg/day), should be instituted within 72 h of Ventricular Assist Device placement (Grade 2C)
• For children who have a Modified BTT shunt, postoperative ASA (1–5 mg/kg/day) or no antithrombotic therapy should be used compared with prolonged therapy using Low Molecular Wt Heparin or Vit K Antagonist (Grade 2C)
• For children who undergo the Norwood procedure, Ultra-Fractionate Heparin immediately after the procedure, with or without ongoing antiplatelet therapy, should be used (Grade 2C)
• For children who undergo Fontan surgery, ASA (1–5 mg/kg/day) or therapeutic Ultra-Fractionate Heparin followed by Vit K Antagonists should be used (Grade 1B)
• In the absence of a documented ongoing cardioembolic source, no anticoagulation or ASA therapy should be given to neonates with first AIS (Grade 1B)
• For neonates with recurrent AIS, anticoagulant or aspirin therapy may be given (Grade 2C)
• For children with AIS not secondary to sickle-cell disease, cardioembolism, or dissection, Ultra-Fractionate Heparin, Low Molecular Wt Heparin, and ASA (1–5 mg/kg/day) are all acceptable options that should be used for 2 years or longer (Grade 1B)
• Children who experience recurrent Acute Ischemic Stroke or Transient Ischemic Attack while taking ASA should be switched to either clopidogrel or anticoagulant therapy (Vit K Antagonist or Low Molecular Wt Heparin) (Grade 2C)
• For children with Kawasaki disease, high-dose ASA (80–100 mg/kg/day) should be given as an anti-inflammatory agent for up to 14 days, followed by low-dose ASA (1–5 mg/kg/day) for 6–8 weeks as prevention against Coronary Artery Aneurysm (Grade 1B)
That brings us to the end of this discussion. The evidences are still pending. However, I have tried to put available stuff for the current decision making. It can help the decision makes to avoid idiosyncrasy and to instill a uniform policy in the work-front. Also, the junior staff may find it useful to clear their own understanding of the current status. Any recommendations on this topic or any suggestions to improve this section can please be sent to drkiranvs@gmail.com The suggestions would be placed in the subsequent posts, if they come and if the posts continue!!
With this, let us get back to our regular feature: Interesting learning scenarios
FIRST OR SECOND
It is well understood that the Tricuspid atresia with NRGA outnumber the other anatomical variants. Most of the children would eventually complete their single ventricle pathways belong to Tricuspid atresia Ib. Is there any study on the number of Tri atrsia IIb having gone through the Fontan completion? Theoretically, Ib can have two sequential restrictions to Qp: one at VSD and other at pulmonary valve. Whereas, for the IIb variant, this reduces to only the latter. Can this contribute to the eventual numbers? Off late, many of the IIb variants I have come across could not make it to the operating table for having not met the criteria. It would be interesting to note the data from various other centres. If anyone have thought of this question, please let me know your observations.
BLUE IS BETTER
This was a paradoxical situation. When the ventricular EDPs are high in a congenital heart disease, the surgical and ITU teams have to exercise extra-caution. We had a 44-year-old with tetralogy-absent pulmonary valve disease with NYHA class III symptoms and baseline SO2 of 89% in room air. Her LV EDP was 22mmHg. The question was on the expectations from surgery in this scenario. The surgical team was not convinced that the surgery would relieve her symptoms, unless a pulmonary component is co-existing. However, the cardiologist was arguing that the high LV EDP is likely to be the culprit and surgery would be beneficial. Our senior surgeon brought out a point: The EDP of a cyanotic ventricle would improve with surgery and that of acyanotic would not. In other words, in adult TOF, the surgery would reduce the high EDP, but not in VSD. The argument sounded logical. Are there any studies or observations in this regard? Please let me know your take on this.
THE SEPTECTOMY SAGA
I came across a 2-month-old with large VSD with pulmonary atresia. This baby also had a hypoplastic TV, hypoplatic muscle bound RV and a stretched PFO with flap open towards LA, shunting Right to Left. The PAs were small sized and the baby saturated 70% in room air. Ideally, there is a need for increasing the Qp and advocating BTT shunt appears logical choice. However, with increase in LA return, would the PFO flap close towards RA? Once this happens, where would the RA decompress? The TV and RV appeared too small to negotiate the RA outflow. Would it not be detrimental to do the BTT shunt alone? Should we be creating a simultaneous ASD? The recommendation was to do an atrial septectomy clubbed with BTT shunt. However, for same reasons discussed in previous posts, this was not perceived as a good idea. Is there an alternate logic? Am I missing something that the surgeons are confident of? What is the experience of the readership in this issue? Please let me know. I shall try to keep the progress of this baby updated in the subsequent posts.
TYPING AND SIZE
What is the criterion for the Rastelli classification of AV canal defect? The individual opinions vary, but it remains the nature of AV valve itself. We had a newborn with complete AV canal defect. The bridging leaflet was sending its chordae onto the crest of IVS. However, the left AV valve component was hypoplastic, resulting in hypoplastic LV. This was followed by DORV and membranous pulmonary atresia. The management would be on single ventricle lines. However, there was some ambiguity on classifying this as type A Rastelli Vs type C. What is the vote of readership? Please let me know how you classify the AV canal defects in your routine practice.
EVIDENCE OF COMPROMISE
We often predict the loss of ventricular cavity in tunnel closures of VSD, especially in DORV, d-malposed setting. However, the assessment is on 2D and that too for RV, which is not a very echo-friendly structure! When we actually, predict such a scenario, are talking of the volumes or functional cavity or total area of contractile elements? Which of them would be an ideal measurement? Depending on the answer, we can actually devise our investigation in future. If anyone has data on this, please inform me.
PEDIATRIC CARDIOLOGY PEARLS
106. There are two frequent variants of the left aortic arch. One is common brachiocephalic trunk, in which the right innominate and left carotid arteries arise from a single origin. This is present in 10% of otherwise normal left arches (29) and usually is of no consequence. The other variant is separate origin of the left vertebral artery from the aortic arch proximal to the takeoff of the left subclavian artery rather than from the subclavian artery. This too is seen in 10% of normal left arches. (Edwards JE. An atlas of Acquired Diseases of the Heart and Great Vessel. Published by WB Saunders, Philadelphia in the year 1961)
107. Small VSDs, sometimes referred to as Roger's defect, are those less than one third the size of the aortic root and impose a high resistance to flow with a resultant large systolic pressure difference between the two ventricles. There is a small left-to-right shunt, normal right ventricular systolic pressure, and essentially normal work characteristics of the ventricles. The magnitude of the left-to-right shunt is related directly to the size of the defect, and there is no tendency for an increase in pulmonary vascular resistance. The pressure gradient across the defect favors the left ventricle throughout the cardiac cycle and can result in a continuous left-to-right shunt. (Levin AE, Spach MS, Canent RV Jr, et al. Ventricular pressure-flow dynamics in ventricular septal defect. In the journal Circulation in 1967 page 430)
108. The fundamental problem in AV canal defect is failure of the endocardial cushions to fuse, creating a defect in the atrioventricular septum. The primum atrial septal component of this defect is usually large. This results in downward displacement of the anterior mitral leaflet to the level of the septal tricuspid leaflet. (Gutgesell HP, Huhta JC. Cardiac septation in atrioventricular canal defect. In Journal of American College of Cardiology in the year 1986 page 1421)
109. Researchers have found a missense mutation in myosin heavy chain 6 (on chromosome 14q12) has been found to cause familial ASD. (Ching YH, Ghosh TK, Cross SJ, et al. Mutation in myosin heavy chain 6 causes atrial septal defect. In journal Nature Genetics in the year 2005 page 423)
110. The first application of a fluid dynamics principle in medicine was given by Roos. It was represented as “Increasing viscosity or decreasing vessel radius leads to an elevation of both arterial pressure and vascular resistance” (Roos A. Poiseuille's law and its limitations in vascular systems. In the journal Med Thoracics in the year 1962 page 224)
That brings us to the end of another post. Please send your responses and reactions to drkiranvs@gmail.com or use the comments box. Please keep the discussions open. I am trying for an interactive module for debating in pediatric cardiology. Please send in your suggestion on this.
Regards
Kiran
In this post, we will see the current evidence on the use of antiplatelet agents in pediatric practice with special emphasis on cardiac patients.
Q1. What are the currently available antiplatelet agents for pediatric use?
1. Aspirin: inhibits platelet function by irreversibly binding to cyclooxygenase (COX)-1
2. Dipyridamole: inhibits adenosine uptake into platelets
3. Clopidogrel: irreversibly binds to the purinergic P2Y12 receptor on platelets
4. Intravenous GP 2b/3a inhibitors abciximab, eptifibatide, and tirofiban: bind to platelet GP 2b/3a receptors, which prevents their cross-linking with fibrinogen and blocks the last common pathway of platelet aggregation
Q2: Why is antiplatelet therapy for children different from adults?
Two separate studies by Rajasekhar and collegues discussed the differences in the functional activities of platelets in newborns and that from adult population. The first was during 1994, in an article titled ‘Neonatal platelets are less reactive than adult platelets to physiological agonists in whole blood’ in the journal Thrombosis and Haemostasis. This was followed by an article in the same journal in 1997 titled ‘Platelet hyporeactivity in very-low-birth-weight neonates’. Israles and colleagues published their data in 2001 in the Journal of Pediatrics. The article was titled ‘Evaluation of primary hemostasis in neonates with a new in vitro platelet function analyzer’ which showed a decreased platelet functional response in neonates than adults. These findings suggested that neonates may require lower weight-adjusted doses of antiplatelet agents to achieve the same level of platelet inhibition as for adults and older children.
Apart from the physiological differences, some practical problems are also observed. The children are more mobile and more likely to fall and injure themselves. This is added on with their lesser degree of understanding and adherence to instructions. Reye’s syndrome is a potential complication. Also, they are less likely to understand the consequences of stopping the therapy or not adhering to the dosage.
Q3: What are the present cardiac interventional indications for antiplatelet therapy in children?
The present cardiac indications would be children who undergo implantation of cardiac devices (such as ventricular assist devices (VADs), septal defect occluders, and stents)
An expert review was published in 2008 by Fu and Hijazi under the title ‘The Amplatzer Septal Occluder, a transcatheter device for atrial septal defect closure’ where they strongly advocated the use of aspirin post-ASD device closure. They have quoted the famous study by Fischer et al published in journal Heart in 2003 with title ‘Experience with transcatheter closure of secundum atrial septal defects using the Amplatzer septal occluder: a single centre study in 236 consecutive patients’. In this study, aspirin was used in all 236 and just one patient had a neurological event after 4 years, attributable to device. The evidence is thus in favour of aspirin in this setting.
The data on aspirin with stent placement is not enough, largely due to lesser numbers done in pediatric population. In a retrospective review published by Ebeid et al in 1997, of nine patients (four were 18 years old or younger), aspirin therapy was administered for at least 1 year after implantation of balloon-expandable stents for coarctation of the aorta, and no patient showed evidence of thromboembolism after an average follow-up period of 18 months. This was published in JACC under the title ‘Use of balloon expandable stents for coarctation of the aorta: initial results and intermediate-term follow-up’. Kutty and Zahn published their data on use of aspirin after stent placement in pediatric population in 2008 in the journal Catheter and Cardiovascular Interventions under the title ‘Interventional therapy for neonates with critical congenital heart disease’. In the same year, Menon and colleagues published ‘Hybrid intraoperative pulmonary artery stent placement for congenital heart disease’ in the AJC. In this retrospective review, 24 patients (14 of whom younger than 18 years) received aspirin after undergoing hybrid pulmonary artery stent implantation secondary to congenital heart disease and did not demonstrate any episodes of stent thrombosis over a mean follow-up period of 19 months.
Q4: What are the cardiac post-surgical indications for antiplatelet therapy?
Any child who needs a systemic-to-pulmonary artery shunt is at the risk of thrombotic event. The studies quoting uselessness of therapy were very small and underpowered (Al Jubair et al in 1998 in Journal Cardiology in the Young ‘Results of 546 Blalock-Taussig shunts performed in 478 patients, Fenton et al in ATS in 2003 ‘Interim mortality in infants with systemic-to-pulmonary artery shunts’ and so on) the overall data is in favour of using aspirin (Motz et al in 1999 in journal Cardiology in the Young ‘Reduced frequency of occlusion of aortopulmonary shunts in infants receiving aspirin’, Li et al in 2007 in journal Circulation ‘Clinical outcomes of palliative surgery including a systemic-to-pulmonary artery shunt in infants with cyanotic congenital heart disease: Does aspirin make a difference? and so on).
In 2002, Monagle and Karl published their data as ‘Thromboembolic problems after the Fontan operation’ in Seminars in Thoracic and Cardiovascular Surgery. They advocated the use of aspirin, as children a with single-ventricle approach the Fontan procedure, they remain at high risk of thromboembolic complications.
The data on the use of antiplatelet agents and anticoagulation agents in post-Fontan group remains conflicting. Seipelt and co-workers wrote ‘Thromboembolic complications after Fontan procedures: comparison of different therapeutic approaches’ in ATS in 2002. This was a retrospective study investigating 87 survivors of Fontan surgery, the rates of thromboembolic complications were similar for the patients who received aspirin (1.6 events/100 patient-years) and those who received warfarin (1.1 events/100 patient-years) but much higher for those who received no antithrombotic therapy (4.2 events/100 patient-years). The journal Circulation published an abstract by Monagle et al in 2008 presented at AHA meeting. It was a multicentre randomized trial comparing heparin/warfarin versus aspirin as primary thromboprophylaxis for two years after Fontan procedure in 111 children with mean age of 3.8 years. During a 27-month follow-up period, thrombosis occurred for 24% of the heparin and warfarin recipients and 21% of the aspirin recipients (p = 0.47). The rate of major bleeding also was the same (1 event per group). These data suggest that anticoagulation and antiplatelet therapies are similarly safe and effective in preventing thrombosis after Fontan surgery. However, the favour of surgeon still remains with warfarin in large many institutes across the globe.
Q5: Role of clopidogrel
The year 2005 saw a review article by Finkelstein and colleagues on ‘Clopidogreal use in Children’ in the Journal of Pediatrics. This review served as the baseline for further research with clopidogrel. In 2008, Maltz et al published ‘Clopidogrel in a pediatric population: safety and efficacy results from a single center’ in journal Pediatric Cardiology. It was a retrospective analysis of 90 children (median age, 6.7 years) receiving various doses of clopidogrel. It had a favourable safety and tolerability profile because only two children, both of whom also received aspirin, experienced major bleeding. An additional three patients receiving aspirin plus clopidogrel experienced minor bleeding.
The only randomized control study on Clopidogrel hitherto has been published by Li et al in 2008 in journal Circulation. Popularly called the PICOLO trail, the article is titled ‘Dosing of clopidogrel for platelet inhibition in infants and young children: primary results of the Platelet Inhibition in Children On cLOpidogrel trail’. In this, 92 young children aged 0 to 24 months with cardiac disease were randomized to receive placebo or clopidogrel 0.01, 0.10, 0.15, or 0.20 mg/kg/day. Via platelet aggregometry, clopidogrel 0.20 mg/kg/day was identified as the dose that provided a level of platelet inhibition similar to that achieved with 75 mg/day for adults. Notably, none of the patients experienced serious hemorrhagic events, and only four patients (2 in the placebo group and 1 each in the clopidogrel 0.01 and 0.20 mg/kg/day groups) experienced minor bleeding. The results of PICOLO underscore the importance of conducting randomized clinical trials with children, particularly dose-finding studies, because the 0.20-mg/kg/day clopidogrel dose identified in PICOLO is five times lower than the 1-mg/kg/day dose extrapolated from adult studies.
The ongoing CLARINET study may come out with the answers sought after by the pediatric cardiologists. The details of the trail can be accessed at http://clinicaltrials.gov/ct2/show/NCT00396877 The trail is by Sanofi-Aventis and Bristol-Myers Squibb and titled ‘Efficacy and safety of clopidogrel in neonates/infants with systemic to pulmonary artery shunt palliation (CLARINET)’ and is using clopidogrel at a dose of 0.20mg/kg/day.
Q6: What are the current recommendations for the use of antithrombotic therapy in children?
The current guidelines are drawn from the 2008 report by Monagle and others published in journal Chest. It is the 8th edition of American College of Chest Physicians Evidence-Based Clinical Practice Guidelines on Antithrombotic therapy in neonates and children. The following are excerpts from the content:
• For children with mechanical prosthetic valves who experience thrombotic events while receiving Vit K Antagonist therapy or who cannot tolerate Vit K Antagonist therapy, ASA should be used (Grade 2C)
• Antiplatelet therapy, either ASA (1–5 mg/kg/day) or Dipyridamole (3–10 mg/kg/day), should be instituted within 72 h of Ventricular Assist Device placement (Grade 2C)
• For children who have a Modified BTT shunt, postoperative ASA (1–5 mg/kg/day) or no antithrombotic therapy should be used compared with prolonged therapy using Low Molecular Wt Heparin or Vit K Antagonist (Grade 2C)
• For children who undergo the Norwood procedure, Ultra-Fractionate Heparin immediately after the procedure, with or without ongoing antiplatelet therapy, should be used (Grade 2C)
• For children who undergo Fontan surgery, ASA (1–5 mg/kg/day) or therapeutic Ultra-Fractionate Heparin followed by Vit K Antagonists should be used (Grade 1B)
• In the absence of a documented ongoing cardioembolic source, no anticoagulation or ASA therapy should be given to neonates with first AIS (Grade 1B)
• For neonates with recurrent AIS, anticoagulant or aspirin therapy may be given (Grade 2C)
• For children with AIS not secondary to sickle-cell disease, cardioembolism, or dissection, Ultra-Fractionate Heparin, Low Molecular Wt Heparin, and ASA (1–5 mg/kg/day) are all acceptable options that should be used for 2 years or longer (Grade 1B)
• Children who experience recurrent Acute Ischemic Stroke or Transient Ischemic Attack while taking ASA should be switched to either clopidogrel or anticoagulant therapy (Vit K Antagonist or Low Molecular Wt Heparin) (Grade 2C)
• For children with Kawasaki disease, high-dose ASA (80–100 mg/kg/day) should be given as an anti-inflammatory agent for up to 14 days, followed by low-dose ASA (1–5 mg/kg/day) for 6–8 weeks as prevention against Coronary Artery Aneurysm (Grade 1B)
That brings us to the end of this discussion. The evidences are still pending. However, I have tried to put available stuff for the current decision making. It can help the decision makes to avoid idiosyncrasy and to instill a uniform policy in the work-front. Also, the junior staff may find it useful to clear their own understanding of the current status. Any recommendations on this topic or any suggestions to improve this section can please be sent to drkiranvs@gmail.com The suggestions would be placed in the subsequent posts, if they come and if the posts continue!!
With this, let us get back to our regular feature: Interesting learning scenarios
FIRST OR SECOND
It is well understood that the Tricuspid atresia with NRGA outnumber the other anatomical variants. Most of the children would eventually complete their single ventricle pathways belong to Tricuspid atresia Ib. Is there any study on the number of Tri atrsia IIb having gone through the Fontan completion? Theoretically, Ib can have two sequential restrictions to Qp: one at VSD and other at pulmonary valve. Whereas, for the IIb variant, this reduces to only the latter. Can this contribute to the eventual numbers? Off late, many of the IIb variants I have come across could not make it to the operating table for having not met the criteria. It would be interesting to note the data from various other centres. If anyone have thought of this question, please let me know your observations.
BLUE IS BETTER
This was a paradoxical situation. When the ventricular EDPs are high in a congenital heart disease, the surgical and ITU teams have to exercise extra-caution. We had a 44-year-old with tetralogy-absent pulmonary valve disease with NYHA class III symptoms and baseline SO2 of 89% in room air. Her LV EDP was 22mmHg. The question was on the expectations from surgery in this scenario. The surgical team was not convinced that the surgery would relieve her symptoms, unless a pulmonary component is co-existing. However, the cardiologist was arguing that the high LV EDP is likely to be the culprit and surgery would be beneficial. Our senior surgeon brought out a point: The EDP of a cyanotic ventricle would improve with surgery and that of acyanotic would not. In other words, in adult TOF, the surgery would reduce the high EDP, but not in VSD. The argument sounded logical. Are there any studies or observations in this regard? Please let me know your take on this.
THE SEPTECTOMY SAGA
I came across a 2-month-old with large VSD with pulmonary atresia. This baby also had a hypoplastic TV, hypoplatic muscle bound RV and a stretched PFO with flap open towards LA, shunting Right to Left. The PAs were small sized and the baby saturated 70% in room air. Ideally, there is a need for increasing the Qp and advocating BTT shunt appears logical choice. However, with increase in LA return, would the PFO flap close towards RA? Once this happens, where would the RA decompress? The TV and RV appeared too small to negotiate the RA outflow. Would it not be detrimental to do the BTT shunt alone? Should we be creating a simultaneous ASD? The recommendation was to do an atrial septectomy clubbed with BTT shunt. However, for same reasons discussed in previous posts, this was not perceived as a good idea. Is there an alternate logic? Am I missing something that the surgeons are confident of? What is the experience of the readership in this issue? Please let me know. I shall try to keep the progress of this baby updated in the subsequent posts.
TYPING AND SIZE
What is the criterion for the Rastelli classification of AV canal defect? The individual opinions vary, but it remains the nature of AV valve itself. We had a newborn with complete AV canal defect. The bridging leaflet was sending its chordae onto the crest of IVS. However, the left AV valve component was hypoplastic, resulting in hypoplastic LV. This was followed by DORV and membranous pulmonary atresia. The management would be on single ventricle lines. However, there was some ambiguity on classifying this as type A Rastelli Vs type C. What is the vote of readership? Please let me know how you classify the AV canal defects in your routine practice.
EVIDENCE OF COMPROMISE
We often predict the loss of ventricular cavity in tunnel closures of VSD, especially in DORV, d-malposed setting. However, the assessment is on 2D and that too for RV, which is not a very echo-friendly structure! When we actually, predict such a scenario, are talking of the volumes or functional cavity or total area of contractile elements? Which of them would be an ideal measurement? Depending on the answer, we can actually devise our investigation in future. If anyone has data on this, please inform me.
PEDIATRIC CARDIOLOGY PEARLS
106. There are two frequent variants of the left aortic arch. One is common brachiocephalic trunk, in which the right innominate and left carotid arteries arise from a single origin. This is present in 10% of otherwise normal left arches (29) and usually is of no consequence. The other variant is separate origin of the left vertebral artery from the aortic arch proximal to the takeoff of the left subclavian artery rather than from the subclavian artery. This too is seen in 10% of normal left arches. (Edwards JE. An atlas of Acquired Diseases of the Heart and Great Vessel. Published by WB Saunders, Philadelphia in the year 1961)
107. Small VSDs, sometimes referred to as Roger's defect, are those less than one third the size of the aortic root and impose a high resistance to flow with a resultant large systolic pressure difference between the two ventricles. There is a small left-to-right shunt, normal right ventricular systolic pressure, and essentially normal work characteristics of the ventricles. The magnitude of the left-to-right shunt is related directly to the size of the defect, and there is no tendency for an increase in pulmonary vascular resistance. The pressure gradient across the defect favors the left ventricle throughout the cardiac cycle and can result in a continuous left-to-right shunt. (Levin AE, Spach MS, Canent RV Jr, et al. Ventricular pressure-flow dynamics in ventricular septal defect. In the journal Circulation in 1967 page 430)
108. The fundamental problem in AV canal defect is failure of the endocardial cushions to fuse, creating a defect in the atrioventricular septum. The primum atrial septal component of this defect is usually large. This results in downward displacement of the anterior mitral leaflet to the level of the septal tricuspid leaflet. (Gutgesell HP, Huhta JC. Cardiac septation in atrioventricular canal defect. In Journal of American College of Cardiology in the year 1986 page 1421)
109. Researchers have found a missense mutation in myosin heavy chain 6 (on chromosome 14q12) has been found to cause familial ASD. (Ching YH, Ghosh TK, Cross SJ, et al. Mutation in myosin heavy chain 6 causes atrial septal defect. In journal Nature Genetics in the year 2005 page 423)
110. The first application of a fluid dynamics principle in medicine was given by Roos. It was represented as “Increasing viscosity or decreasing vessel radius leads to an elevation of both arterial pressure and vascular resistance” (Roos A. Poiseuille's law and its limitations in vascular systems. In the journal Med Thoracics in the year 1962 page 224)
That brings us to the end of another post. Please send your responses and reactions to drkiranvs@gmail.com or use the comments box. Please keep the discussions open. I am trying for an interactive module for debating in pediatric cardiology. Please send in your suggestion on this.
Regards
Kiran
ಶುಕ್ರವಾರ, ನವೆಂಬರ್ 12, 2010
Dr Kiran welcomes all to the new post of NH blog.
I should thank the responses I got for a small (?emotional) outburst in the last post. My teachers whom I revere a lot, my friends who have a cordial relationship, my colleagues who I thought would never have read the blog – all came together to assure that the blog is being read and for various reasons it should be continued. That was indeed a great reinforcement.
There was a suggestion also: that I should invite few big people to write for the blog. To the best of my knowledge, I do it in every post! Of course, neither the name nor the pattern of blog suggests that I own the blog. Let me reiterate once again: The blog belongs to everyone who holds any passion towards its objective put up below the masthead. All are formally invited to be a part of the content of this blog once again.
The section of “Current controversies in Pediatric Cardiology” seems to have evoked better response. I shall try to continue this section till I get drained off the ideas!
This time in this segment, I am dealing with the use of cath data in decision making. This is possibly one area which has minimal consensus and maximal idiosyncratic interpretation. We shall see the available evidence for this.
Q1: Which anesthetic agents should be used for cath studies in children?
Various drug protocols are drawn for this purpose, but the supporting literature is not uniform. Laird et al in 2002 presented their data in the journal Anesthesia and Analgesia under the title ‘Pulmonary-to-systemic blood flow ratio effects of Sevoflurane, Isoflurane, Halothane, and Fentanyl/Midazolam with 100% oxygen in children with congenital heart disease’, in which they discouraged the use of inhaled drugs for their myocardial depressant effects. Of the intravenous choices, long back in 1990, Berman et al in their article titled ‘Hemodynamic effects of Ketamine in children undergoing cardiac catheterization’ published in journal Pediatric Cardilogy had observed that Ketamine given in boluses would increase pulmonary vascular resistance, raking up a controversy. In a study published by Williams et al in 1999 in the journal Anesthesia and Analgesia titled ‘The hemodynamic effects of Propofol in children with congenital heart disease’, it was noted that Propofol given as a single drug seems to decrease systemic vascular resistance, making calculations of shunts unreliable. The same opinion was shared by Oklu and colleagues in 2003 in their article ‘Which anesthetic agent alters the hemodynamic status during pediatric catheterization? Comparison of Propofol versus Ketamine’ published in the Journal of Cardiothoracic and Vascular Anesthesia. In this prospective randomized study, continuously administered ketamine did not affect pulmonary vascular resistance significantly. Few workers in this field decided to go for low dose combination modules. Jobier et al used Midazolam with Ketamine. Their data was published in journal Pediatric Cardiology in 2003 under the title ‘Use of low-dose Ketamine and/or Midazolam for pediatric cardiac catheterization: is an anesthesiologist needed?’ In the same year, Kogan et al published ‘Propofol-Ketamine mixture for anesthesia in pediatric patients undergoing cardiac catheterization’ in the Journal of Cardiothoracic and Vascular Anesthesia. These two studies have formed the basis for the evidence in this regard, under class IIa indication.
In pediatric patients undergoing cardiac catheterization for hemodynamic measurements, sedation and analgesia can be achieved by combining midazolan with fentanyl, or by using low-dose ketamine in association with either midazolan or low-dose propofol. Continuous intravenous administration is preferable. Multi-drug cocktails, inhaled agents, propofol as single drug and bolus administration of any drugs should be avoided. (Level of evidence: B)
Q2. How to assess and interpret Qp, Qs, SVRI and PVRI?
Presumed entities while using Ficks principle have jeopardized the calculations since its onset! Yet, it is continued for the lack of better alternatives. The landmark article by Wilkinson in the journal Heart in 2001 titled ‘Congenital heart disease: haemodynamic calculations in the catheter laboratory’ serves as the basic manual for formulae and technical advice. As per the advice from Wilkinson, if an assumption is considered, then more than one value should be obtained. The classical paper of LaFarge and Miettinen on ‘The estimation of oxygen consumption’ published in journal Cardiovascular Research in the year 1970 serves as the core guide and has universal usage. However, it should be acknowledged that in infants and toddlers, it provides higher oxygen consumption values making the calculations appear ridiculous sometimes. To overcome this issue, two studies have come up. In 1989, Lindahl wrote ‘Oxygen consumption and carbon dioxide elimination in infants and children during anaesthesia and surgery’ in British Journal of Anaesthesia. This was followed by ‘Oxygen consumption in infants and children during heart catheterization’ by Lundell and co-workers in the journal Pediatric Cardiology in 1996. These values settled the issue for some extent but are still far from accurate. The problem intensifies in cyanotic children especially for Fontan circulation. Shanahan et al in 2003 published ‘The influence of measured versus assumed uptake of oxygen in assessing pulmonary vascular resistance in patients with a bidirectional Glenn anastomosis’ in journal Cardiology in the Young. Here, they noted that the measured values of oxygen consumption were far greater than the assumed ones and suitability for Fontan completion may not be reliable with the data obtained. Bergstra et al had published ‘Assumed oxygen consumption based on calculation from dye dilution cardiac output: an improved formula’ in the European Heart Journal in 1995. The same was seconded in 2000 by Berger in European Heart Journal again in article ‘Possibilities and impossibilities in the evaluation of pulmonary vascular disease in congenital heart defects’. Dye dilution can be a suitable bridge before something better comes up. Hence the recommendation:
In patients with congenital heart disease associated with pulmonary hypertension, pulmonary and systemic blood flow and vascular resistance should be calculated preferably using measured oxygen consumption, with attention to all other potential sources of error. (Indication class: IIa, level of evidence: B)
If measured values of oxygen consumption cannot be obtained, calculations should be performed assuming alternative values at the upper and lower limits of the likely range for that given patient, and results expressed as intervals. If the likely range is too wide and a narrow one is required for decision-making, assumed values should not be used at all. (Indication class: IIb, level of evidence: B)
This sounds more logical than the words ‘cath has its own fallacies’ after making the patient and the performer go through the gruesome ordeal!
Q3: Pulmonary vasoreactivity and operability
Historically, the operability assessment was a radical step towards safety of surgery. One among the strong criticisms faced by the present technique is that at high oxygen concentrations, determination of arterial PO2 is necessary and measurement of oxygen consumption is not possible. In 1996, Berner et al published ‘Inhaled nitric oxide to test the vasodilator capacity of the pulmonary vascular bed in children with long-standing pulmonary hypertension and congenital heart disease’ in the American Journal of Cardiology. This was followed by article by Atz et al in 1999 in JACC, titled ‘Combined effects of nitric oxide and oxygen during acute pulmonary vasodilator testing’. These articles accounted pulmonary vascular resistance and pulmonary to systemic resistance ratio, and the way they change during an acute vasodilator challenge have been taken into consideration. The article by Atz also defined maximal achievable stimulation without any toxic side-effects by 10 minute administration of a mixture containing >90% oxygen and 80 ppm nitric oxide. With these values as baseline, many workers tried to improvise the effect. Cannon et al published their study in 2005 in journal Pediatric Cardiology under the title ‘Nitric oxide in the evaluation of congenital heart disease with pulmonary hypertension: factors related to nitric oxide response’ in which they used 20ppm NO without enhancing the oxygen concentration. Alternative strategy of starting at low concentrations with gradual increases until response is also advocated, but would involve longer hours and multiple samplings, both of which are not advocated in children.
Hence, the recommendations would be:
In patients with congenital heart disease and pulmonary hypertension, there are no simple ways to predict outcomes following correction of the cardiac defects. Therefore, operability (which does not imply a warranty of favourable outcome without any residual elevation of pulmonary pressures) should be defined on an individual basis, taking into account a substantial amount of clinical data as well as information derived from noninvasive and sometimes invasive evaluation. (Class I indication, Level of evidence:C)
Also, in patients with biventricular circulations and baseline elevation of pulmonary vascular resistance > 6 Wood units∙m2 and a pulmonary to systemic resistance ratio of >0.3, a >20% decrease in both parameters during inhalation of low concentrations of nitric oxide, with respective final values of <6 Wood units∙m2 and < 0.3 indicates that vasoconstriction plays a role, and suggests that from the hemodynamic point of view, correction of the defect may be considered as a reasonable approach. (Class I indication, Level of evidence:B)
This marks the end of this topic. I have taken up 3 relevant questions and drawn 5 recommendations as per the available evidence. Please let me know if you would like to have a complete bibliographic notation of the studies mentioned in the discussion. If so, I shall provide them at the end of discussion to avoid the incoherence of flow. Please send your comments and suggestions to drkiranvs@gmail.com to enable others to understand your ideas and flow of thoughts.
With this, let us continue towards our regular feature: Interesting learning scenarios.
HYPOPLASTIC LV, HYPER-CORONARIES!
This 9-day-old baby presented to us in a perfectly asymptomatic condition. On echo, we found an aneurysmal IAS with a moderate L to R shunt, small MV (Z-score minus 5), small, non-apex reaching LV with intact IVS, small aortic valve (Z-score minus 3) with near absence of antegrade flow. The hypoplastic LV was decompressing by a moderate MR. Great artery relationship was normal. What surprised us were a normal sized ascending and transverse aortae and the neck vessels. Further distally, there was a small, bidirectionally shunting PDA with not much retrograde filling. How is the brain fed? What can explain the size of proximal aorta? The surprise element of the picture was unusually dilated coronaries filling retrograde. The RCA was massive and coursed along the right AV groove. The LMC was enlarged with normal branching, but could not be traced much. The distal end of any of the coronaries could not be traced on echo. It was clear on colour Doppler that the flow in the coronaries was towards the aorta. Surprisingly, there was no wall motion abnormality or functional impairment of the right ventricle. It is the first time that I had seen such a combination. Is this described? What are the management options in this kid? Would it still require the first stage of Norwood despite having a good sized proximal aorta? Can we create a VSD to decompress the LV so as to minimise the MR? Please let me know your experiences with such scenarios. I shall keep the readership updated if I get any further info on this.
ISOLATED TR
We do come across good number of isolated sever TR in many children. They are usually not much symptomatic. The tolerability of the heart problem is good in them. The symptoms are more often non-cardiac than the other way. How should such children be treated? The ECS guidelines of 2007 specify wait-and-watch policy. Should we actually wait for RV to fail? Isn’t the prognosis worse after RV failure? Can we go by any additional data like MRI for RV volumes? Is this data good for taking a radical decision? Our senior surgeons always maintain that the patient should ‘earn’ his surgery. How would such subgroup earn the surgery? The overall data that I could gather justify the stand taken by ECS. Is the policy any different in other places? Please let me know your takes on this issue.
SEQUENTIAL OBSTRUCTION
Please take a look on this scenario. A toddler with Tricuspid atresia 1B. The VSD is reported as restrictive. Pulmonary valve is good sized and PA sizes are OK. The ASD is restrictive, as evidenced by data on echo and cath. There are no systemic symptoms like edema or pulsatile liver. If the reverse pulmonary venous wedge pressure turns out to be 16mmHg, can we confidently do a BD Glenn and an atrial septectomy? In other words, when there is a sequential obstruction (as restrictive ASD and restrictive looking VSD in this case), can we relieve the proximal (by atrial septectomy) and be confident of the status of distal (VSD)? What would happen to PA pressures with atrial septectomy? How controlled can a concomitant PA band be? When Fontan completion does appear to be on cards, can one take the risk of closing the antegrade flow via PA? These were some of the questions that came up during one of our discussions. If anyone has sorted out this scenario earlier, please let us know the possible alternatives in such cases.
ROLE OF NUMBERS
What is the yield of cath data in ASD with RV dysfunction? We came across a 13-year-old with this picture. He had a large ASD with severe PAH and RV dysfunction. He went through the cath procedure. The PA pressures were half-systemic. The RV EDP was 12mmHg. The RV injection is not done in such cases, so cath assessment of RV function was not possible. The software for calculating the RV volumes is not available with us. There were no additional lesions. There is a clear text-book indication for cath in this scenario. But, what is the yield? What cath data would have influenced a different strategy? If not a complete closure, we would have done a reduction of ASD size, leaving a fossa ovalis defect and contemplating a device closure in future as per need. Is the risk/benefit ratio justified in such scenarios? Should we be drawing a different strategy for such cases? Is my analogy wrong or am I missing something in the entire picture? Please let me know.
BATSON’S PLEXUS
Often, we find the surgical team talking of Batson’s plexus during description of AP collaterals. I found this data on vertebral venous plexus otherwise called Batson’s plexus: Any of four interconnected venous networks surrounding the vertebral column; anterior external vertebral venous plexus, the small system around the vertebral bodies; posterior external vertebral venous plexus, the extensive system around the vertebral processes; anterior internal vertebral venous plexus, the system running the length of the vertebral canal anterior to the dura; posterior internal vertebral venous plexus, the system running the length of the vertebral canal posterior to the dura; the latter two constitute the epidural venous plexus.
Throughout this description, I could not find a single link that can connect Batson’s plexus to AP collaterals of cardiovascular utility. Please let me know if any study has been conducted to show that they are indeed Batson’s plexus.
PEDIATRIC CARDIOLOGY PEARLS
101. When the degree of valvular pulmonary stenosis is severe enough to cause a decrease in fetal right ventricular output, a larger-than-normal atrial right-to-left shunt is established in utero. This condition has been termed critical pulmonary stenosis. (Freed MD, Rosenthal AR, Bernhard WF, et al. Critical pulmonary stenosis with diminutive right ventricle in neonates. In journal Circulation in the year 1973 page 875)
102. Unlike the patient with a duct-dependent pulmonary circulation and pulmonary atresia with ventricular septal defect, the caliber of the pulmonary arteries in patients with pulmonary atresia and intact ventricular septum rarely is a major determinant of outcome. It is important to recognize that significant coarctation of the left pulmonary artery associated with the site of ductal insertion can occur in the neonate and the young infant. This may be, in part, mediated by the observation that the arterial duct tends to close earlier in patients with pulmonary atresia and intact septum than it does in patients with pulmonary atresia and ventricular septal defect. (Marino B, Guccione P, Carotti A, et al. Ductus arteriosus in pulmonary atresia with and without ventricular septal defect. Anatomic and functional differences. In Scandinavian Journal of Thoracic and Cardiovascular Surgery in year 1992 page 93)
103. In Pulmonary Atresia with VSD, the blood supply to the lungs is entirely from the systemic arterial circulation. The sources are the ductus arteriosus, systemic-to-pulmonary collateral arteries, occasionally a coronary artery, and plexuses of bronchial or pleural arteries. Ductal and collateral sources may coexist in the same patient but only rarely coexist in the same lung. (Liao PK, Edwards WD, Julsrud PR, et al. Pulmonary blood supply in patients with pulmonary atresia and ventricular septal defect. In Journal of American College of Cardiology in the year 1985 page 1343)
104. Maternal treatment with trimethadione or paramethadione during the pregnancy has been associated with the development of multiple anomalies, including cardiac septal defects and TOF. (Feldman GL, Weaver DD, Lovrien EW. The fetal trimethadione syndrome. In American Journal of Diseases in Children in the year 1977 page 1389)
105. Truncal valve stenosis, when present, usually is associated with nodular and dysplastic cusps. (Butto F, Lucas R, Edwards J. Persistent truncus arteriosus: Pathologic anatomy in 54 cases. In the journal Pediatric Cardiology in the year 1986 page 95)
With this, I conclude this post. Thanks again for the support. If you come across any controversial topic that needs discussion and evidence search, please let me know. I shall try to discuss the topic, crediting you for the copyright of discussion! Please feel free to put your opinions in the comments box or use my email id drkiranvs@gmail.com to send your suggestions and comments
Regards
Kiran
I should thank the responses I got for a small (?emotional) outburst in the last post. My teachers whom I revere a lot, my friends who have a cordial relationship, my colleagues who I thought would never have read the blog – all came together to assure that the blog is being read and for various reasons it should be continued. That was indeed a great reinforcement.
There was a suggestion also: that I should invite few big people to write for the blog. To the best of my knowledge, I do it in every post! Of course, neither the name nor the pattern of blog suggests that I own the blog. Let me reiterate once again: The blog belongs to everyone who holds any passion towards its objective put up below the masthead. All are formally invited to be a part of the content of this blog once again.
The section of “Current controversies in Pediatric Cardiology” seems to have evoked better response. I shall try to continue this section till I get drained off the ideas!
This time in this segment, I am dealing with the use of cath data in decision making. This is possibly one area which has minimal consensus and maximal idiosyncratic interpretation. We shall see the available evidence for this.
Q1: Which anesthetic agents should be used for cath studies in children?
Various drug protocols are drawn for this purpose, but the supporting literature is not uniform. Laird et al in 2002 presented their data in the journal Anesthesia and Analgesia under the title ‘Pulmonary-to-systemic blood flow ratio effects of Sevoflurane, Isoflurane, Halothane, and Fentanyl/Midazolam with 100% oxygen in children with congenital heart disease’, in which they discouraged the use of inhaled drugs for their myocardial depressant effects. Of the intravenous choices, long back in 1990, Berman et al in their article titled ‘Hemodynamic effects of Ketamine in children undergoing cardiac catheterization’ published in journal Pediatric Cardilogy had observed that Ketamine given in boluses would increase pulmonary vascular resistance, raking up a controversy. In a study published by Williams et al in 1999 in the journal Anesthesia and Analgesia titled ‘The hemodynamic effects of Propofol in children with congenital heart disease’, it was noted that Propofol given as a single drug seems to decrease systemic vascular resistance, making calculations of shunts unreliable. The same opinion was shared by Oklu and colleagues in 2003 in their article ‘Which anesthetic agent alters the hemodynamic status during pediatric catheterization? Comparison of Propofol versus Ketamine’ published in the Journal of Cardiothoracic and Vascular Anesthesia. In this prospective randomized study, continuously administered ketamine did not affect pulmonary vascular resistance significantly. Few workers in this field decided to go for low dose combination modules. Jobier et al used Midazolam with Ketamine. Their data was published in journal Pediatric Cardiology in 2003 under the title ‘Use of low-dose Ketamine and/or Midazolam for pediatric cardiac catheterization: is an anesthesiologist needed?’ In the same year, Kogan et al published ‘Propofol-Ketamine mixture for anesthesia in pediatric patients undergoing cardiac catheterization’ in the Journal of Cardiothoracic and Vascular Anesthesia. These two studies have formed the basis for the evidence in this regard, under class IIa indication.
In pediatric patients undergoing cardiac catheterization for hemodynamic measurements, sedation and analgesia can be achieved by combining midazolan with fentanyl, or by using low-dose ketamine in association with either midazolan or low-dose propofol. Continuous intravenous administration is preferable. Multi-drug cocktails, inhaled agents, propofol as single drug and bolus administration of any drugs should be avoided. (Level of evidence: B)
Q2. How to assess and interpret Qp, Qs, SVRI and PVRI?
Presumed entities while using Ficks principle have jeopardized the calculations since its onset! Yet, it is continued for the lack of better alternatives. The landmark article by Wilkinson in the journal Heart in 2001 titled ‘Congenital heart disease: haemodynamic calculations in the catheter laboratory’ serves as the basic manual for formulae and technical advice. As per the advice from Wilkinson, if an assumption is considered, then more than one value should be obtained. The classical paper of LaFarge and Miettinen on ‘The estimation of oxygen consumption’ published in journal Cardiovascular Research in the year 1970 serves as the core guide and has universal usage. However, it should be acknowledged that in infants and toddlers, it provides higher oxygen consumption values making the calculations appear ridiculous sometimes. To overcome this issue, two studies have come up. In 1989, Lindahl wrote ‘Oxygen consumption and carbon dioxide elimination in infants and children during anaesthesia and surgery’ in British Journal of Anaesthesia. This was followed by ‘Oxygen consumption in infants and children during heart catheterization’ by Lundell and co-workers in the journal Pediatric Cardiology in 1996. These values settled the issue for some extent but are still far from accurate. The problem intensifies in cyanotic children especially for Fontan circulation. Shanahan et al in 2003 published ‘The influence of measured versus assumed uptake of oxygen in assessing pulmonary vascular resistance in patients with a bidirectional Glenn anastomosis’ in journal Cardiology in the Young. Here, they noted that the measured values of oxygen consumption were far greater than the assumed ones and suitability for Fontan completion may not be reliable with the data obtained. Bergstra et al had published ‘Assumed oxygen consumption based on calculation from dye dilution cardiac output: an improved formula’ in the European Heart Journal in 1995. The same was seconded in 2000 by Berger in European Heart Journal again in article ‘Possibilities and impossibilities in the evaluation of pulmonary vascular disease in congenital heart defects’. Dye dilution can be a suitable bridge before something better comes up. Hence the recommendation:
In patients with congenital heart disease associated with pulmonary hypertension, pulmonary and systemic blood flow and vascular resistance should be calculated preferably using measured oxygen consumption, with attention to all other potential sources of error. (Indication class: IIa, level of evidence: B)
If measured values of oxygen consumption cannot be obtained, calculations should be performed assuming alternative values at the upper and lower limits of the likely range for that given patient, and results expressed as intervals. If the likely range is too wide and a narrow one is required for decision-making, assumed values should not be used at all. (Indication class: IIb, level of evidence: B)
This sounds more logical than the words ‘cath has its own fallacies’ after making the patient and the performer go through the gruesome ordeal!
Q3: Pulmonary vasoreactivity and operability
Historically, the operability assessment was a radical step towards safety of surgery. One among the strong criticisms faced by the present technique is that at high oxygen concentrations, determination of arterial PO2 is necessary and measurement of oxygen consumption is not possible. In 1996, Berner et al published ‘Inhaled nitric oxide to test the vasodilator capacity of the pulmonary vascular bed in children with long-standing pulmonary hypertension and congenital heart disease’ in the American Journal of Cardiology. This was followed by article by Atz et al in 1999 in JACC, titled ‘Combined effects of nitric oxide and oxygen during acute pulmonary vasodilator testing’. These articles accounted pulmonary vascular resistance and pulmonary to systemic resistance ratio, and the way they change during an acute vasodilator challenge have been taken into consideration. The article by Atz also defined maximal achievable stimulation without any toxic side-effects by 10 minute administration of a mixture containing >90% oxygen and 80 ppm nitric oxide. With these values as baseline, many workers tried to improvise the effect. Cannon et al published their study in 2005 in journal Pediatric Cardiology under the title ‘Nitric oxide in the evaluation of congenital heart disease with pulmonary hypertension: factors related to nitric oxide response’ in which they used 20ppm NO without enhancing the oxygen concentration. Alternative strategy of starting at low concentrations with gradual increases until response is also advocated, but would involve longer hours and multiple samplings, both of which are not advocated in children.
Hence, the recommendations would be:
In patients with congenital heart disease and pulmonary hypertension, there are no simple ways to predict outcomes following correction of the cardiac defects. Therefore, operability (which does not imply a warranty of favourable outcome without any residual elevation of pulmonary pressures) should be defined on an individual basis, taking into account a substantial amount of clinical data as well as information derived from noninvasive and sometimes invasive evaluation. (Class I indication, Level of evidence:C)
Also, in patients with biventricular circulations and baseline elevation of pulmonary vascular resistance > 6 Wood units∙m2 and a pulmonary to systemic resistance ratio of >0.3, a >20% decrease in both parameters during inhalation of low concentrations of nitric oxide, with respective final values of <6 Wood units∙m2 and < 0.3 indicates that vasoconstriction plays a role, and suggests that from the hemodynamic point of view, correction of the defect may be considered as a reasonable approach. (Class I indication, Level of evidence:B)
This marks the end of this topic. I have taken up 3 relevant questions and drawn 5 recommendations as per the available evidence. Please let me know if you would like to have a complete bibliographic notation of the studies mentioned in the discussion. If so, I shall provide them at the end of discussion to avoid the incoherence of flow. Please send your comments and suggestions to drkiranvs@gmail.com to enable others to understand your ideas and flow of thoughts.
With this, let us continue towards our regular feature: Interesting learning scenarios.
HYPOPLASTIC LV, HYPER-CORONARIES!
This 9-day-old baby presented to us in a perfectly asymptomatic condition. On echo, we found an aneurysmal IAS with a moderate L to R shunt, small MV (Z-score minus 5), small, non-apex reaching LV with intact IVS, small aortic valve (Z-score minus 3) with near absence of antegrade flow. The hypoplastic LV was decompressing by a moderate MR. Great artery relationship was normal. What surprised us were a normal sized ascending and transverse aortae and the neck vessels. Further distally, there was a small, bidirectionally shunting PDA with not much retrograde filling. How is the brain fed? What can explain the size of proximal aorta? The surprise element of the picture was unusually dilated coronaries filling retrograde. The RCA was massive and coursed along the right AV groove. The LMC was enlarged with normal branching, but could not be traced much. The distal end of any of the coronaries could not be traced on echo. It was clear on colour Doppler that the flow in the coronaries was towards the aorta. Surprisingly, there was no wall motion abnormality or functional impairment of the right ventricle. It is the first time that I had seen such a combination. Is this described? What are the management options in this kid? Would it still require the first stage of Norwood despite having a good sized proximal aorta? Can we create a VSD to decompress the LV so as to minimise the MR? Please let me know your experiences with such scenarios. I shall keep the readership updated if I get any further info on this.
ISOLATED TR
We do come across good number of isolated sever TR in many children. They are usually not much symptomatic. The tolerability of the heart problem is good in them. The symptoms are more often non-cardiac than the other way. How should such children be treated? The ECS guidelines of 2007 specify wait-and-watch policy. Should we actually wait for RV to fail? Isn’t the prognosis worse after RV failure? Can we go by any additional data like MRI for RV volumes? Is this data good for taking a radical decision? Our senior surgeons always maintain that the patient should ‘earn’ his surgery. How would such subgroup earn the surgery? The overall data that I could gather justify the stand taken by ECS. Is the policy any different in other places? Please let me know your takes on this issue.
SEQUENTIAL OBSTRUCTION
Please take a look on this scenario. A toddler with Tricuspid atresia 1B. The VSD is reported as restrictive. Pulmonary valve is good sized and PA sizes are OK. The ASD is restrictive, as evidenced by data on echo and cath. There are no systemic symptoms like edema or pulsatile liver. If the reverse pulmonary venous wedge pressure turns out to be 16mmHg, can we confidently do a BD Glenn and an atrial septectomy? In other words, when there is a sequential obstruction (as restrictive ASD and restrictive looking VSD in this case), can we relieve the proximal (by atrial septectomy) and be confident of the status of distal (VSD)? What would happen to PA pressures with atrial septectomy? How controlled can a concomitant PA band be? When Fontan completion does appear to be on cards, can one take the risk of closing the antegrade flow via PA? These were some of the questions that came up during one of our discussions. If anyone has sorted out this scenario earlier, please let us know the possible alternatives in such cases.
ROLE OF NUMBERS
What is the yield of cath data in ASD with RV dysfunction? We came across a 13-year-old with this picture. He had a large ASD with severe PAH and RV dysfunction. He went through the cath procedure. The PA pressures were half-systemic. The RV EDP was 12mmHg. The RV injection is not done in such cases, so cath assessment of RV function was not possible. The software for calculating the RV volumes is not available with us. There were no additional lesions. There is a clear text-book indication for cath in this scenario. But, what is the yield? What cath data would have influenced a different strategy? If not a complete closure, we would have done a reduction of ASD size, leaving a fossa ovalis defect and contemplating a device closure in future as per need. Is the risk/benefit ratio justified in such scenarios? Should we be drawing a different strategy for such cases? Is my analogy wrong or am I missing something in the entire picture? Please let me know.
BATSON’S PLEXUS
Often, we find the surgical team talking of Batson’s plexus during description of AP collaterals. I found this data on vertebral venous plexus otherwise called Batson’s plexus: Any of four interconnected venous networks surrounding the vertebral column; anterior external vertebral venous plexus, the small system around the vertebral bodies; posterior external vertebral venous plexus, the extensive system around the vertebral processes; anterior internal vertebral venous plexus, the system running the length of the vertebral canal anterior to the dura; posterior internal vertebral venous plexus, the system running the length of the vertebral canal posterior to the dura; the latter two constitute the epidural venous plexus.
Throughout this description, I could not find a single link that can connect Batson’s plexus to AP collaterals of cardiovascular utility. Please let me know if any study has been conducted to show that they are indeed Batson’s plexus.
PEDIATRIC CARDIOLOGY PEARLS
101. When the degree of valvular pulmonary stenosis is severe enough to cause a decrease in fetal right ventricular output, a larger-than-normal atrial right-to-left shunt is established in utero. This condition has been termed critical pulmonary stenosis. (Freed MD, Rosenthal AR, Bernhard WF, et al. Critical pulmonary stenosis with diminutive right ventricle in neonates. In journal Circulation in the year 1973 page 875)
102. Unlike the patient with a duct-dependent pulmonary circulation and pulmonary atresia with ventricular septal defect, the caliber of the pulmonary arteries in patients with pulmonary atresia and intact ventricular septum rarely is a major determinant of outcome. It is important to recognize that significant coarctation of the left pulmonary artery associated with the site of ductal insertion can occur in the neonate and the young infant. This may be, in part, mediated by the observation that the arterial duct tends to close earlier in patients with pulmonary atresia and intact septum than it does in patients with pulmonary atresia and ventricular septal defect. (Marino B, Guccione P, Carotti A, et al. Ductus arteriosus in pulmonary atresia with and without ventricular septal defect. Anatomic and functional differences. In Scandinavian Journal of Thoracic and Cardiovascular Surgery in year 1992 page 93)
103. In Pulmonary Atresia with VSD, the blood supply to the lungs is entirely from the systemic arterial circulation. The sources are the ductus arteriosus, systemic-to-pulmonary collateral arteries, occasionally a coronary artery, and plexuses of bronchial or pleural arteries. Ductal and collateral sources may coexist in the same patient but only rarely coexist in the same lung. (Liao PK, Edwards WD, Julsrud PR, et al. Pulmonary blood supply in patients with pulmonary atresia and ventricular septal defect. In Journal of American College of Cardiology in the year 1985 page 1343)
104. Maternal treatment with trimethadione or paramethadione during the pregnancy has been associated with the development of multiple anomalies, including cardiac septal defects and TOF. (Feldman GL, Weaver DD, Lovrien EW. The fetal trimethadione syndrome. In American Journal of Diseases in Children in the year 1977 page 1389)
105. Truncal valve stenosis, when present, usually is associated with nodular and dysplastic cusps. (Butto F, Lucas R, Edwards J. Persistent truncus arteriosus: Pathologic anatomy in 54 cases. In the journal Pediatric Cardiology in the year 1986 page 95)
With this, I conclude this post. Thanks again for the support. If you come across any controversial topic that needs discussion and evidence search, please let me know. I shall try to discuss the topic, crediting you for the copyright of discussion! Please feel free to put your opinions in the comments box or use my email id drkiranvs@gmail.com to send your suggestions and comments
Regards
Kiran
ಶುಕ್ರವಾರ, ನವೆಂಬರ್ 5, 2010
Dr Kiran welcomes all to this new post of pediatric cardiology blog.
I have often thought if I should wind up the blog. It takes lots of time for me to get the things compiled. It takes keen observation and note-making to get the facts correct. It takes good amount of thinking to write in a language different from my mother-tongue. When the blog was started, the name was chosen carefully so that everyone in the department would think it is their own and would contribute. All these expectations went the same way my other expectations go.... right into the drain!
Still, I am continuing it. Since the comments I get are minimum, I don’t even know if anyone is reading the blog at all! So, even if I stop, I don’t think anyone would be affected. “We never knew you existed; anyways – good bye” would probably be the response. When something does not make any difference, why bother?
Despite the apparent pessimism, I shall continue this blog as long as feasible. It gives me an opportunity to be alert, express, think and explore. It has given me new ideas on learning. It has taught me how to work (for blog) without expectation (of comments). The time investment done on this blog is not a waste for me as of now atleast. Of course, bitter pills would not matter if one is sure of the commitment.
Let me congratulate our fellows for their enthusiasm to explore. An idea originated when I was writing for one of the posts for this blog. I proposed debating for the fellows in the department as a part of their academics. I hand-picked about 25 topics and ran through the available literature. I chose those topics which had good number of pros and cons. A list of 5 topics were given to the fellows and they chose one topic for the first-ever debate for Pediatric Cardiology fellows at NH. The topic they chose was “The role of ACE inhibitors in Post-Fontan status”. They debated well with a great deal of zeal and preparation. Congrats to Drs Shweta Nathani, Kavya Mrutyunjaya, Prashanth Patil and Dhanya Warriar – good job; keep it up!
Let me get to our new feature of the blog: The current status of controversies in pediatric cardiology.
This post, I have chosen Eisenmengarization. We shall ask few questions and check the level of evidence for each of them whenever available or get some support from literature.
Q1. The role of long term oxygen therapy:
Oxygen therapy on the first look appears to be an impressive choice. In 1985, Bowyer et al reported the ‘Effect of long term oxygen treatment at home in children with pulmonary vascular disease’ in British Heart Journal. Improved survival has been reported in a small group of children with pulmonary vascular disease receiving long-term oxygen therapy. This study was quoted to advocate the use of routine home oxygen therapy. However, a much larger study by Sandoval et al in 2001 on ‘Nocturnal oxygen therapy in patients with the Eisenmenger syndrome’ got published in the American Journal of Respiratory and Critical Care Medicine. The study showed that nocturnal oxygen therapy did not improve symptoms, exercise capacity, and outcome in adult patients with Eisenmenger syndrome. Hence, home oxygen therapy is a class IIb indication. Routine use of long-term oxygen therapy cannot be recommended. However, selected patients with associated lung pathology may benefit from oxygen inhalation. (level of evidence:B)
Q2. The role of Bosentan:
The BREATHE-5 (Bosentan Randomized Trial of Endothelial Antagonist Therapy) trial by Galie et al published in Circulation in 2006 looked at Bosentan therapy in patients with Eisenmenger syndrome. It was a multicenter, double-blind, randomized, placebo controlled study. Here, bosentan improved exercise endurance at 16 weeks, without any deleterious effects on gas exchange. As the level symptoms in the enrolling subjects increase (class III and IV), the results are likely to be earlier and better. However, in a retrospective study published by Adriaenssens T et al in European Heart Journal in 2006 titled ‘Advanced therapy may delay the need for transplantation in patients with the Eisenmenger syndrome’, no survival advantage could be demonstrated among those who received the newer therapies in comparison with those who remained on standard care. Many of these patients out of a cohort of 43 had class II symptoms. Hence, use of Bosentan is a class I indication. Bosentan may be used in patients with the Eisenmenger syndrome with class III symptoms to improve exercise capacity and hemodynamics. The long-term benefits of any drugs in this syndrome should be evaluated on the basis of long follow-up periods. Results of studies with this design are not available at present. (Level of evidence:B)
Q3: Role of Anticoagulation
Broberg and colleagues have done extensive research on this issue. In one of the articles titled ‘Massive pulmonary artery thrombosis with haemoptysis in adults with Eisenmenger’s syndrome: a clinical dilemma’, published in Heart in the year 2004, they showed the tendencies in such patients for the development of pulmonary arterial thrombosis. This was followed by another study of theirs published in the Journal of American College of Cardiology in the year 2007, titled ‘Pulmonary arterial thrombosis in Eisenmenger syndrome is associated with biventricular dysfunction and decreased pulmonary blood velocity’. These studies pointed at the advantages of routine anticoagulation in this subset of patients. However, the risk of bleeding episodes cannot be negated at the same time. One needs a fine balance between use and monitoring. Since the risk of bleeding exceeds the benefit in the potentially unmonitorable subgroup, the routine use of anticoagulation falls under class IIb indication. The routine anticoagulation is still remains controversial in patients with the Eisenmenger syndrome. Marked blood hyperviscosity, altered chest tomography suggesting pulmonary arterial thrombosis, and chronic atrial flutter or fibrillation are findings that may point toward the need for anticoagulation. However, chronic anticoagulation should be avoided if adequate monitoring is not feasible. (Level of evidence:C)
Q4: Pregnancy and Eisenmengarization
Yentis and colleagues in 1998 did a systematic survey in this regard. Their article titled ‘Eisenmenger’s syndrome in pregnancy: maternal and fetal mortality in the 1990s’, published in British Journal of Obstetrics and Gynaecology showed a substantial risk of mortality to both fetus and the mother. The same opinion was shared by Diller and Gatzoulis in the year 2007. The article titled ‘Pulmonary vascular disease in adults with congenital heart disease’ published in Circulation reiterated the same opinion. The risks of pregnancy should be explained to women with the Eisenmenger syndrome as soon as the diagnosis is confirmed and the options for contraception should be given. Thus, avoidance of pregnancy becomes a class I indication. Early termination of pregnancy is recommended. Careful monitoring and specialized follow-up of inevitable pregnancy in selected cases is advised. (Level of evidence:C)
Q5: Routine phlebotomy
Perloff and colleagues have detailed this issue many times. In an article published in the Annals of Internal Medicine in the year 1988 titled ‘Adults with cyanotic congenital heart disease: hematologic management’, they documented worsening of iron deficiency with phlebotomies. They had an argument that the compensated secondary erythrocytosis is better tolerated and does not mandate routine blood-letting. In another article published in 1993 in Circulation titled ‘Risk of stroke in adults with cyanotic congenital heart disease’, an increased risk of stroke was also documented by them. Broberg and colleagues in 2006 published their data in the JACC titled ‘Blood viscosity and its relationship to iron deficiency, symptoms, and exercise capacity in adults with cyanotic congenital heart disease’, showing a further reduction in exercise tolerance with phlebotomies. Phlebotomies should be indicated strictly to relieve hyperviscosity-related symptoms such as blurry vision, headaches, dizziness, arthralgia and worsening of dyspnea. In all instances, maintaining an iron-replete state is crucial. Avoidance of phlebotomy is a class I indication and the level of evidence is B.
This marks the end of this topic. In future, I intend to take up an issue of importance and address atleast 5 questions with appropriate studies and available evidence. Hopefully, it should be of assistance to anyone interested in these topics. Any further queries can be addressed in the comments box or to drkiranvs@gmail.com I shall try to address those questions on timely basis.
Any suggestions about this new section are welcome.
With this, let us get back to our regular feature: Interesting learning scenarios:
HIGH YET LOW
In cases of transposition of great arteries with small ASD and large VSD, the desaturation is usually disproportionate to the extent of lesion. We had a 2 year old with TGA, large non-routable VSD, small ASD and severe PS with SO2 of 60%. The PA pressure on cath was 15mmHg. The issue was to go for a BD Glenn shunt. On chest radiograph, the Qp was not bad and the echo showed a satisfactory pulmonary venous return. So, it is just not the Qp which is the cause for desaturation here. The more likely culprit might be the inadequate ASD. Despite the presence of a large VSD, it is the interatrial communication that more effective in mixing. Hence, the argument was to add an atrial septectomy to BD Glenn. The problem is, for atrail septectomy, the patient has to go through the bypass pump, whereas BD Glenn is done off-pump. So, one has to be categorical in showing the benefit for subjecting someone to pump. What is your experience in this issue? Please let the others know.
USE AND MISUSE
“Is the diagnositic cath an entity in the current practice of pediatric cardiology?” is a hotly debated subject. The pros and cons are numerous. However, some amount of discretion can definitely be entertained in this regard. The grey zones are in plenty and the decisions may fluctuate with regard to merit of the case. I have discussed a 2-year-old in one of my earlier posts. This kid had a large VSD, a moderate ASD and PAH. In such combination, we would expect RA and RV to get dilated. However, this child had LA and LV dilatation. The TV annulus corresponded to zero Z-score and RV was tripartitie and reaching apex. Since the child saturated 94% on room air, had plethoric lung fields and the shunts were completely left to right, the operability was not doubtful. However, the paradoxical size of RV was worrisome. Cath may give us RV EDP. How useful would this data be? Cath was done, but RV injection was not done due to severe PAH. The final data acquired showed operability. Can such caths be avoided? There was nothing of importance that could not be predicted. Finally, the surgery was the same as pre-cath recommendation. What is the opinion of the readership? How would other institutes handle such issue?
HALF OR ONE-AND-A-HALF?
We had a 4-year-old with a large VSD, smallish TV, smallish RV (not reaching apex) and a moderate sized ASD. The ASD shunted right to left. There was some antegrade flow through the muscle bundles of RVOT. On cath, the PA pressure was 12mmHg. The decision was between an isolated BD Glenn shunt against a one-and-a-half ventricle repair. The latter would definitely be a superior option, but would involve resection of RVOT muscle bundles. The effectiveness of RVOT clearance would determine whether the ASD should be kept open or not. Also, if the pulmonary valve gets inadvertently damaged in the process and starts leaking, the efficacy of Glenn would come down and the smallish RV may not take the additional load of PR. This may again necessitate the ASD to be kept open. The overall picture would indicate a delicate balance. How controlled can such procedures be? Is risking a delicate balance between a fine RVOT with no damage to pulmonary valve a superior option to a non-risky BD Glenn? How would the readership vote? Please let me know. I shall update you on the outcome of this child.
ACQUIRED RESTICTIONS
Can Tricuspid atresia with restrictive ASD live upto 8 years without any intervention? Looks like an unusual association. We did see an eight year old with this picture saturating 74% in room air. The RA pressure was 12mmHg and the LA was at 8mmHg in a tricuspid atresia IIB. The cath data was otherwise OK for single pump repair except for the low McGoon ratio of 1.5. The decision was to go for a BD Glenn shunt. The same question popped up again: Should septectomy be added? One argument was not to trust the numbers of cath data and to go ahead only with off-pump BD Glenn. The other argument was a possibility of an acquired restriction of interatrial communication and thereby giving rise to symptoms as well as the numbers shown in the cath data. Is the acquired restriction of interatrial restriction possible as a part of natural history of tricuspid atresia? Is such a thing reported or seen? Please let me know your experience.
ALL OR SOME OR NONE
It was a conflict of contrasts. We had an 11-year-old saturating 75% in room air but with surprisingly active (NYHA Class 1 symptoms) with balanced AV canal defect, DORV, d-malposed great vessels with supracardiac TAPVC to SVC-RA junction. The conflict in the clinical picture led to the conflicting opinions. The cath data otherwise suited Fontan repair, but the co-existing TAPVC was not in favour. The question was whether a simple BD Glenn be done or not. One argument was that at 11 years of age, isolated BD Glenn would only be adding to surgical risk without much benefit to an already asymptomatic child. The other argument was to do with his SO2. At 75% SO2, even a 25% cardiac output ensured from BD Glenn shunt into the Qp along with some antegrade flow from RVOT would be far superior over a period of time than leaving him alone. So, rerouting the TAPVC to LA and a concomitant BD Glenn was to be considered. Of the three choices (Fontan OR BD Glenn with TAPVC rerouting OR nothing) which would you favour? Do you have any different logic to justify your stand? Please let me know.
PEDIATRIC CARDIOLOGY PEARLS:
96. Systemic arterial desaturation is present to some extent in every patient with tricuspid atresia because of complete admixture of the systemic and pulmonary venous returns. Hypercyanotic spells can occur in patients with tricuspid atresia as a result of either a decrease in the size of the VSD or infundibular narrowing. (Dick M, Fyler DC, Nadas AS. Tricuspid atresia: Clinical course in 101 patients. In American Journal of Cardiology in the year 1975 page 327)
97. Scimitar syndrome is associated with other anomalies, including hypoplasia of the right lung, anomalies of the bronchial system, horseshoe lung, secondary dextrocardia, hypoplasia of the right pulmonary artery, anomalous arterial connection to the right lung from the aorta, and pulmonary sequestration. (Gao Y, Burrows PE, Benson LN, et al. Scimitar syndrome in infancy. In Journal of American College of Cardiology in the year 1993 page 873)
98. In 1942, Streeter proposed classifying human embryos in 25 age groups, or horizons, each representing 2 days of embryonic life. He later omitted the last two stages because he thought that stage XXIII could be considered the last stage of embryonic development. This approach has been generally accepted for determining the age of human embryo. (Streeter GL. Developmental horizons in human embryos: Description of age group XI, 13 to 20 somites, and age group XXII, 21 to 29 somites. In the journal Carnegie Institutes Contributions to Embryology in the year 1942 page 211)
99. During fetal life, the partial pressure of oxygen to which the ductus arteriosus is normally exposed is 18 to 28 mm Hg. An increase in pO2, as occurs with ventilation after birth, constricts the ductus arteriosus in mature fetal animals. (Heymann MA, Rudolph AM. Control of the ductus arteriosus. In the journal Physiology Review in the year 1975 page 62)
100. Two major types of vascular anomalies were defined: Hemangiomas and malformations. Hemangiomas are benign tumors of infancy that demonstrate endothelial cell hyperplasia during the postnatal period (proliferative phase) and that undergo spontaneous regression over a 5- to 8-year period (involutive phase), without metastasis. Vascular malformations result from errors of vascular morphogenesis; they grow commensurately with the child and exhibit a normal rate of endothelial cell turnover. Vascular malformations are subdivided anatomically into groups based on the predominant anomalous vascular tissue: Capillary, lymphatic, venous, arterial, or a combination of vessel types. (Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: A classification based on endothelial characteristics. In journal of Plastic and Reconstructive Surgery in the year 1982 page 412)
With this, we wind up this post. I would be interested in your comments on the new section. Please use the comments link. Click on ‘comments’ to open a comments box and post your writing in it. Or you can also use my email id drkiranvs@gmail.com to put up your comments- both careful and caustic are welcome!
Regards
Kiran
I have often thought if I should wind up the blog. It takes lots of time for me to get the things compiled. It takes keen observation and note-making to get the facts correct. It takes good amount of thinking to write in a language different from my mother-tongue. When the blog was started, the name was chosen carefully so that everyone in the department would think it is their own and would contribute. All these expectations went the same way my other expectations go.... right into the drain!
Still, I am continuing it. Since the comments I get are minimum, I don’t even know if anyone is reading the blog at all! So, even if I stop, I don’t think anyone would be affected. “We never knew you existed; anyways – good bye” would probably be the response. When something does not make any difference, why bother?
Despite the apparent pessimism, I shall continue this blog as long as feasible. It gives me an opportunity to be alert, express, think and explore. It has given me new ideas on learning. It has taught me how to work (for blog) without expectation (of comments). The time investment done on this blog is not a waste for me as of now atleast. Of course, bitter pills would not matter if one is sure of the commitment.
Let me congratulate our fellows for their enthusiasm to explore. An idea originated when I was writing for one of the posts for this blog. I proposed debating for the fellows in the department as a part of their academics. I hand-picked about 25 topics and ran through the available literature. I chose those topics which had good number of pros and cons. A list of 5 topics were given to the fellows and they chose one topic for the first-ever debate for Pediatric Cardiology fellows at NH. The topic they chose was “The role of ACE inhibitors in Post-Fontan status”. They debated well with a great deal of zeal and preparation. Congrats to Drs Shweta Nathani, Kavya Mrutyunjaya, Prashanth Patil and Dhanya Warriar – good job; keep it up!
Let me get to our new feature of the blog: The current status of controversies in pediatric cardiology.
This post, I have chosen Eisenmengarization. We shall ask few questions and check the level of evidence for each of them whenever available or get some support from literature.
Q1. The role of long term oxygen therapy:
Oxygen therapy on the first look appears to be an impressive choice. In 1985, Bowyer et al reported the ‘Effect of long term oxygen treatment at home in children with pulmonary vascular disease’ in British Heart Journal. Improved survival has been reported in a small group of children with pulmonary vascular disease receiving long-term oxygen therapy. This study was quoted to advocate the use of routine home oxygen therapy. However, a much larger study by Sandoval et al in 2001 on ‘Nocturnal oxygen therapy in patients with the Eisenmenger syndrome’ got published in the American Journal of Respiratory and Critical Care Medicine. The study showed that nocturnal oxygen therapy did not improve symptoms, exercise capacity, and outcome in adult patients with Eisenmenger syndrome. Hence, home oxygen therapy is a class IIb indication. Routine use of long-term oxygen therapy cannot be recommended. However, selected patients with associated lung pathology may benefit from oxygen inhalation. (level of evidence:B)
Q2. The role of Bosentan:
The BREATHE-5 (Bosentan Randomized Trial of Endothelial Antagonist Therapy) trial by Galie et al published in Circulation in 2006 looked at Bosentan therapy in patients with Eisenmenger syndrome. It was a multicenter, double-blind, randomized, placebo controlled study. Here, bosentan improved exercise endurance at 16 weeks, without any deleterious effects on gas exchange. As the level symptoms in the enrolling subjects increase (class III and IV), the results are likely to be earlier and better. However, in a retrospective study published by Adriaenssens T et al in European Heart Journal in 2006 titled ‘Advanced therapy may delay the need for transplantation in patients with the Eisenmenger syndrome’, no survival advantage could be demonstrated among those who received the newer therapies in comparison with those who remained on standard care. Many of these patients out of a cohort of 43 had class II symptoms. Hence, use of Bosentan is a class I indication. Bosentan may be used in patients with the Eisenmenger syndrome with class III symptoms to improve exercise capacity and hemodynamics. The long-term benefits of any drugs in this syndrome should be evaluated on the basis of long follow-up periods. Results of studies with this design are not available at present. (Level of evidence:B)
Q3: Role of Anticoagulation
Broberg and colleagues have done extensive research on this issue. In one of the articles titled ‘Massive pulmonary artery thrombosis with haemoptysis in adults with Eisenmenger’s syndrome: a clinical dilemma’, published in Heart in the year 2004, they showed the tendencies in such patients for the development of pulmonary arterial thrombosis. This was followed by another study of theirs published in the Journal of American College of Cardiology in the year 2007, titled ‘Pulmonary arterial thrombosis in Eisenmenger syndrome is associated with biventricular dysfunction and decreased pulmonary blood velocity’. These studies pointed at the advantages of routine anticoagulation in this subset of patients. However, the risk of bleeding episodes cannot be negated at the same time. One needs a fine balance between use and monitoring. Since the risk of bleeding exceeds the benefit in the potentially unmonitorable subgroup, the routine use of anticoagulation falls under class IIb indication. The routine anticoagulation is still remains controversial in patients with the Eisenmenger syndrome. Marked blood hyperviscosity, altered chest tomography suggesting pulmonary arterial thrombosis, and chronic atrial flutter or fibrillation are findings that may point toward the need for anticoagulation. However, chronic anticoagulation should be avoided if adequate monitoring is not feasible. (Level of evidence:C)
Q4: Pregnancy and Eisenmengarization
Yentis and colleagues in 1998 did a systematic survey in this regard. Their article titled ‘Eisenmenger’s syndrome in pregnancy: maternal and fetal mortality in the 1990s’, published in British Journal of Obstetrics and Gynaecology showed a substantial risk of mortality to both fetus and the mother. The same opinion was shared by Diller and Gatzoulis in the year 2007. The article titled ‘Pulmonary vascular disease in adults with congenital heart disease’ published in Circulation reiterated the same opinion. The risks of pregnancy should be explained to women with the Eisenmenger syndrome as soon as the diagnosis is confirmed and the options for contraception should be given. Thus, avoidance of pregnancy becomes a class I indication. Early termination of pregnancy is recommended. Careful monitoring and specialized follow-up of inevitable pregnancy in selected cases is advised. (Level of evidence:C)
Q5: Routine phlebotomy
Perloff and colleagues have detailed this issue many times. In an article published in the Annals of Internal Medicine in the year 1988 titled ‘Adults with cyanotic congenital heart disease: hematologic management’, they documented worsening of iron deficiency with phlebotomies. They had an argument that the compensated secondary erythrocytosis is better tolerated and does not mandate routine blood-letting. In another article published in 1993 in Circulation titled ‘Risk of stroke in adults with cyanotic congenital heart disease’, an increased risk of stroke was also documented by them. Broberg and colleagues in 2006 published their data in the JACC titled ‘Blood viscosity and its relationship to iron deficiency, symptoms, and exercise capacity in adults with cyanotic congenital heart disease’, showing a further reduction in exercise tolerance with phlebotomies. Phlebotomies should be indicated strictly to relieve hyperviscosity-related symptoms such as blurry vision, headaches, dizziness, arthralgia and worsening of dyspnea. In all instances, maintaining an iron-replete state is crucial. Avoidance of phlebotomy is a class I indication and the level of evidence is B.
This marks the end of this topic. In future, I intend to take up an issue of importance and address atleast 5 questions with appropriate studies and available evidence. Hopefully, it should be of assistance to anyone interested in these topics. Any further queries can be addressed in the comments box or to drkiranvs@gmail.com I shall try to address those questions on timely basis.
Any suggestions about this new section are welcome.
With this, let us get back to our regular feature: Interesting learning scenarios:
HIGH YET LOW
In cases of transposition of great arteries with small ASD and large VSD, the desaturation is usually disproportionate to the extent of lesion. We had a 2 year old with TGA, large non-routable VSD, small ASD and severe PS with SO2 of 60%. The PA pressure on cath was 15mmHg. The issue was to go for a BD Glenn shunt. On chest radiograph, the Qp was not bad and the echo showed a satisfactory pulmonary venous return. So, it is just not the Qp which is the cause for desaturation here. The more likely culprit might be the inadequate ASD. Despite the presence of a large VSD, it is the interatrial communication that more effective in mixing. Hence, the argument was to add an atrial septectomy to BD Glenn. The problem is, for atrail septectomy, the patient has to go through the bypass pump, whereas BD Glenn is done off-pump. So, one has to be categorical in showing the benefit for subjecting someone to pump. What is your experience in this issue? Please let the others know.
USE AND MISUSE
“Is the diagnositic cath an entity in the current practice of pediatric cardiology?” is a hotly debated subject. The pros and cons are numerous. However, some amount of discretion can definitely be entertained in this regard. The grey zones are in plenty and the decisions may fluctuate with regard to merit of the case. I have discussed a 2-year-old in one of my earlier posts. This kid had a large VSD, a moderate ASD and PAH. In such combination, we would expect RA and RV to get dilated. However, this child had LA and LV dilatation. The TV annulus corresponded to zero Z-score and RV was tripartitie and reaching apex. Since the child saturated 94% on room air, had plethoric lung fields and the shunts were completely left to right, the operability was not doubtful. However, the paradoxical size of RV was worrisome. Cath may give us RV EDP. How useful would this data be? Cath was done, but RV injection was not done due to severe PAH. The final data acquired showed operability. Can such caths be avoided? There was nothing of importance that could not be predicted. Finally, the surgery was the same as pre-cath recommendation. What is the opinion of the readership? How would other institutes handle such issue?
HALF OR ONE-AND-A-HALF?
We had a 4-year-old with a large VSD, smallish TV, smallish RV (not reaching apex) and a moderate sized ASD. The ASD shunted right to left. There was some antegrade flow through the muscle bundles of RVOT. On cath, the PA pressure was 12mmHg. The decision was between an isolated BD Glenn shunt against a one-and-a-half ventricle repair. The latter would definitely be a superior option, but would involve resection of RVOT muscle bundles. The effectiveness of RVOT clearance would determine whether the ASD should be kept open or not. Also, if the pulmonary valve gets inadvertently damaged in the process and starts leaking, the efficacy of Glenn would come down and the smallish RV may not take the additional load of PR. This may again necessitate the ASD to be kept open. The overall picture would indicate a delicate balance. How controlled can such procedures be? Is risking a delicate balance between a fine RVOT with no damage to pulmonary valve a superior option to a non-risky BD Glenn? How would the readership vote? Please let me know. I shall update you on the outcome of this child.
ACQUIRED RESTICTIONS
Can Tricuspid atresia with restrictive ASD live upto 8 years without any intervention? Looks like an unusual association. We did see an eight year old with this picture saturating 74% in room air. The RA pressure was 12mmHg and the LA was at 8mmHg in a tricuspid atresia IIB. The cath data was otherwise OK for single pump repair except for the low McGoon ratio of 1.5. The decision was to go for a BD Glenn shunt. The same question popped up again: Should septectomy be added? One argument was not to trust the numbers of cath data and to go ahead only with off-pump BD Glenn. The other argument was a possibility of an acquired restriction of interatrial communication and thereby giving rise to symptoms as well as the numbers shown in the cath data. Is the acquired restriction of interatrial restriction possible as a part of natural history of tricuspid atresia? Is such a thing reported or seen? Please let me know your experience.
ALL OR SOME OR NONE
It was a conflict of contrasts. We had an 11-year-old saturating 75% in room air but with surprisingly active (NYHA Class 1 symptoms) with balanced AV canal defect, DORV, d-malposed great vessels with supracardiac TAPVC to SVC-RA junction. The conflict in the clinical picture led to the conflicting opinions. The cath data otherwise suited Fontan repair, but the co-existing TAPVC was not in favour. The question was whether a simple BD Glenn be done or not. One argument was that at 11 years of age, isolated BD Glenn would only be adding to surgical risk without much benefit to an already asymptomatic child. The other argument was to do with his SO2. At 75% SO2, even a 25% cardiac output ensured from BD Glenn shunt into the Qp along with some antegrade flow from RVOT would be far superior over a period of time than leaving him alone. So, rerouting the TAPVC to LA and a concomitant BD Glenn was to be considered. Of the three choices (Fontan OR BD Glenn with TAPVC rerouting OR nothing) which would you favour? Do you have any different logic to justify your stand? Please let me know.
PEDIATRIC CARDIOLOGY PEARLS:
96. Systemic arterial desaturation is present to some extent in every patient with tricuspid atresia because of complete admixture of the systemic and pulmonary venous returns. Hypercyanotic spells can occur in patients with tricuspid atresia as a result of either a decrease in the size of the VSD or infundibular narrowing. (Dick M, Fyler DC, Nadas AS. Tricuspid atresia: Clinical course in 101 patients. In American Journal of Cardiology in the year 1975 page 327)
97. Scimitar syndrome is associated with other anomalies, including hypoplasia of the right lung, anomalies of the bronchial system, horseshoe lung, secondary dextrocardia, hypoplasia of the right pulmonary artery, anomalous arterial connection to the right lung from the aorta, and pulmonary sequestration. (Gao Y, Burrows PE, Benson LN, et al. Scimitar syndrome in infancy. In Journal of American College of Cardiology in the year 1993 page 873)
98. In 1942, Streeter proposed classifying human embryos in 25 age groups, or horizons, each representing 2 days of embryonic life. He later omitted the last two stages because he thought that stage XXIII could be considered the last stage of embryonic development. This approach has been generally accepted for determining the age of human embryo. (Streeter GL. Developmental horizons in human embryos: Description of age group XI, 13 to 20 somites, and age group XXII, 21 to 29 somites. In the journal Carnegie Institutes Contributions to Embryology in the year 1942 page 211)
99. During fetal life, the partial pressure of oxygen to which the ductus arteriosus is normally exposed is 18 to 28 mm Hg. An increase in pO2, as occurs with ventilation after birth, constricts the ductus arteriosus in mature fetal animals. (Heymann MA, Rudolph AM. Control of the ductus arteriosus. In the journal Physiology Review in the year 1975 page 62)
100. Two major types of vascular anomalies were defined: Hemangiomas and malformations. Hemangiomas are benign tumors of infancy that demonstrate endothelial cell hyperplasia during the postnatal period (proliferative phase) and that undergo spontaneous regression over a 5- to 8-year period (involutive phase), without metastasis. Vascular malformations result from errors of vascular morphogenesis; they grow commensurately with the child and exhibit a normal rate of endothelial cell turnover. Vascular malformations are subdivided anatomically into groups based on the predominant anomalous vascular tissue: Capillary, lymphatic, venous, arterial, or a combination of vessel types. (Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: A classification based on endothelial characteristics. In journal of Plastic and Reconstructive Surgery in the year 1982 page 412)
With this, we wind up this post. I would be interested in your comments on the new section. Please use the comments link. Click on ‘comments’ to open a comments box and post your writing in it. Or you can also use my email id drkiranvs@gmail.com to put up your comments- both careful and caustic are welcome!
Regards
Kiran
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