Congenital Cardiac Anesthesia Society
A Section of the the Society for Pediatric Anesthesia

{“questions”:{“115eb”:{“id”:”115eb”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Nicholas Houska, DO and Raveendra Morchi, MD – University of Colorado, Children’s Hospital Colorado \r\n\r\nA 4-month-old male presents for surgical closure of a large ventricular septal defect (VSD) due to failure to thrive and feeding intolerance. Which of the following types of VSD is associated with the HIGHEST risk of injury to the conduction system and subsequent heart block during surgical closure?”,”desc”:”EXPLANATION \r\nSeptation of the ventricles occurs in the first trimester and is intimately related to development of the atrioventricular canals and the outflow tracts. The muscular septum forms from an infolding of ventricular muscle which develops to align with the conal septum of the ventricular outflow tracts. The final area of septation is the membranous septum which develops from the endocardial cushions. The development of the of the atrioventricular node, His-Purkinje system, and bundle branches anatomically coincide with the development of the ventricular septum. \r\n\r\nThere are multiple systems of nomenclature in common usage to describe and classify VSDs, which has led to significant confusion in the literature and clinical practice. To provide uniformity of language and improve communication, the International Society for Nomenclature of Pediatric and Congenital Heart Disease has proposed a classification system which has been accepted by the World Health Organization into the 11th iteration of the international classification of diseases. Under this classification, VSDs are divided into four major groups with descriptors added for the various subtypes within each group. The four groups are: perimembranous central, inlet, trabecular muscular, and outlet. Of these, the perimembranous central type is the most common, comprising greater than 80% of clinically significant VSDs. \r\n\r\nOne of the most serious complications after surgical closure of a ventricular septal defect (VSD) is complete heart block, having a significant impact on long term morbidity. Perimembranous VSDs are intimately associated with the conduction system at the inferoposterior margin, namely the AV node, Bundle of His, and right bundle branch, and are at the highest risk of surgically-induced heart block (see the image below \u2013 by R. Morchi, MD, used by permission). Careful surgical technique and suture placement in this area is essential to prevent damage to the conduction system and subsequent heart block. There is also risk of perioperative heart block after closure of an inlet VSD due to close proximity to the conduction system. Trabecular muscular and outlet VSDs are located in a more remote location from the major components of the conduction system and are much less likely to result in surgical heart block after surgical closure. With improvement in surgical techniques over the years, the current incidence of complete heart block after VSD closure is less than one percent.\r\n\r\n\t\r\n\r\n\r\n \r\n\r\n \r\nREFERENCES \r\nLopez L, Houyel L, Colan SD, et al. Classification of ventricular septal defects for the eleventh iteration of the international classification of diseases\u2014striving for consensus: a report from the international society for nomenclature of paediatric and congenital heart disease. The Annals of Thoracic Surgery <\/em>. 2018;106(5):1578-1589.\r\n\r\nGholampour-Dehaki M, Zareh A, Babaki S, Javadikasgari H. Conduction disorders in continuous versus interrupted suturing technique in ventricular septal defect surgical repair. Res Cardiovasc Med <\/em>. 2016;5(1).\r\n\r\nJonas RA. Vnetricular Septal Defect. In: Comprehensive Surgical Management of Congenital Heart Disease <\/em>.2nd ed. CRC Press; 2014. 331-346.\r\n\r\nAndersen H\u00d8, de Leval MR, Tsang VT, Elliott MJ, Anderson RH, Cook AC. Is complete heart block after surgical closure of ventricular septum defects still an issue? The Annals of Thoracic Surgery <\/em>. 2006;82(3):948-956.\r\n\r\nLamers WH, Moorman AFM. Cardiac septation: a late contribution of the embryonic primary myocardium to heart morphogenesis. Circulation Research <\/em>. 2002;91(2):93-103.\r\n”,”hint”:””,”answers”:{“21lqw”:{“id”:”21lqw”,”image”:””,”imageId”:””,”title”:”A. Perimembranous Central”,”isCorrect”:”1″},”6djzy”:{“id”:”6djzy”,”image”:””,”imageId”:””,”title”:”B. Trabecular Muscular”},”7yr2w”:{“id”:”7yr2w”,”image”:””,”imageId”:””,”title”:”C. Outlet”}}}}}

{“questions”:{“97cp5”:{“id”:”97cp5″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Jeffrey C. Waldman MD, and Nicholas M. Houska, DO – Children\u2019s Hospital Colorado, University of Colorado School of Medicine, Aurora, CO \r\n\r\nThe duration of cardiopulmonary resuscitation (CPR) in a heart transplant donor is a known risk factor for decreased post-transplant survival. What DURATION of CPR performed on a heart transplant donor is associated with decreased post-transplant survival? “,”desc”:”EXPLANATION \r\nThe mortality of children awaiting heart transplantation is higher than any other solid organ transplant. Infants have the highest rate of waitlist mortality (25-30%), and children demonstrate a significantly higher risk of death compared to adults. This is related to the limited availability of donor organs and recipient factors such as age, weight, diagnosis, clinical status, and limited options for mechanical circulatory support. \r\n\r\nDonor characteristics that are associated with refusal for organ donation include gender, blood-type, Centers for Disease Control (CDC) \u201chigh risk\u201d criteria, reduced left ventricular ejection fraction (LVEF), and inotrope usage. Historically, there has been a decrease in the number of organs accepted for transplantation when a donor undergoes CPR. Among pediatric cardiac transplant physicians\/providers, there is also considerable variability in the evaluation of transplant donors, with no standardization of criteria for donor candidacy. \r\n\r\nA retrospective study by Kulshrestha et al from 2001 to 2021 using the United Network for Organ Sharing (UNOS) database compared the acceptance rate of donor hearts according to 1) whether the donor received CPR and 2) the duration of CPR. More than five thousand heart transplant recipients under the age of 18 years old were identified and survival analysis was performed to identify the duration of CPR which resulted in decreased post-transplant survival. A duration of CPR greater than 55 minutes in the donor resulted in a statistically significant decrease in post-transplant survival versus duration of CPR less than 55 minutes (mean survival 11.3 vs 10.2 years, p=0.03). During the study period, 51% of donors received CPR before organ procurement. Acceptance rate of the heart was lower when the donor received CPR as compared to no CPR (54 vs 66%, p less than 0.001) and decreased as the duration of CPR increased. Among the recipient cohort, 52% received a heart from a donor requiring CPR. With an inflection point in survival identified, the recipient cohort was divided into three groups: no donor CPR, CPR \u2264 55 minutes, and CPR greater than 55 minutes. Differences between the groups were identified and further analysis was performed to control for confounding variables. There was no difference in graft failure in recipients who received a heart transplant from a donor NOT requiring CPR as compared to recipients with a donor that had CPR \u2264 55 minutes. CPR duration greater than 55 minutes predicted worse post-transplant survival (HR 1.4 [1.03-1.90]) relative to no CPR, but CPR duration less than or equal to 55 minutes did not predict worsened survival (HR 1.02 [0.90-1.17]) relative to no CPR. Other significant variables affecting post-transplant survival include donor age, race of the recipient, renal dysfunction and dialysis in the recipient, extracorporeal membrane oxygenation in the recipient, and congenital heart disease in the recipient. \r\n\r\n \r\nREFERENCES \r\nAlmond CS, Thiagarajan RR, Piercey GE, et al. Waiting list mortality among children listed for heart transplantation in the United States. Circulation <\/em>. 2009;119:717-27.\r\n\r\n\r\nDipchand AI. Current state of pediatric cardi ac transplantation. Ann Cardiothorac Surg <\/em>. 2018;7:31-55.\r\n\r\nGodown J, Kirk R, Joong A, et al. Variability in donor selection among pediatric heart transplant providers: Results from an international survey. Pediatr Transplant <\/em>. 2019;23:e13417.\r\n\r\nKulshrestha K, Greenberg JW, Guzman-Gomez AM, et al. Up to an hour of donor resuscitation does not affect pediatric heart transplantation survival. Ann Thorac Surg <\/em>. Published online June 2023:S0003497523005696.\r\n”,”hint”:””,”answers”:{“mqpbo”:{“id”:”mqpbo”,”image”:””,”imageId”:””,”title”:”A.\t> 15 minutes”},”avdqu”:{“id”:”avdqu”,”image”:””,”imageId”:””,”title”:”B.\t> 35minutes”},”57ae6″:{“id”:”57ae6″,”image”:””,”imageId”:””,”title”:”C.\t> 55 minutes”,”isCorrect”:”1″}}}}}

{“questions”:{“unq3h”:{“id”:”unq3h”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Nicholas Houska, DO – University of Colorado, Children\u2019s Hospital Colorado \r\n\r\nA 1-week-old, 3.6 kg neonate is admitted to the cardiac intensive care unit with decreased responsiveness, poor urine output and diminished femoral pulses. A transthoracic echocardiogram reveals coarctation of the aorta.\r\n \r\nWhat is the MOST likely coexisting congenital heart defect in this patient?”,”desc”:”EXPLANATION \r\nBicuspid aortic valve (BAV) is the most common congenital heart defect with a prevalence of 1-2%. Coarctation of the aorta (CoA) occurs in three out of every 10,000 live births but is more common when occurring in conjunction with other congenital heart defects. BAV and CoA have a male to female predominance of 2:1to 4:1. In addition, both are associated with Turner syndrome. While approximately 7% of patients with a BAV will also have a coarctation of the aorta, upwards of 85 % of patients with CoA will have concurrent bicuspid aortic valve. The frequent association of CoA and BAV together suggest an underlying generalized arteriopathy. This may place patients at risk for future complications and the need for further catheter and surgical based interventions. Bicuspid aortic valve is the most common cause of aortic valve stenosis and aortic valve replacement in patients under 60 years of age. \r\n\r\nCoarctation of the aorta can lead to hypertension, which often persists even after complete repair. Approximately 10% of patients with aortic coarctation also have intracranial aneurysms, increasing the risk of cerebrovascular accidents. Other complications include congestive heart failure, endocarditis, and aortic dissection and rupture secondary to dilatation of the aorta. The rate of recurrence of aortic coarctation requiring reintervention after surgical repair is reported to be 5-15%. Due to the long-term complications of BAV and CoA, regular follow-up with a cardiologist is recommended. \r\n\r\n\r\n\r\n \r\nREFERENCES \r\nSinning C, Zengin E, Kozlik-Feldmann R, et al. Bicuspid aortic valve and aortic coarctation in congenital heart disease-important aspects for treatment with focus on aortic vasculopathy. Cardiovasc Diagn Ther<\/em>. 2018;8(6):780-788. \r\n\r\nWarnes CA. Bicuspid aortic valve and coarctation: two villains part of a diffuse problem. Heart <\/em>.2003;89(9):965-966. \r\n\r\nTorok RD, Campbell MJ, Fleming GA, Hill KD. Coarctation of the aorta: Management from infancy to adulthood. World J Cardiol<\/em>. 2015;7(11):765-775. \r\n\r\nBacha E, Hijazi ZM. (2023) Management of coarctation of the aorta. UpToDate<\/em>. Retrieved July 4, 2023, from: https:\/\/www.uptodate.com\/contents\/management-of-coarctation-of-the-aorta\r\n”,”hint”:””,”answers”:{“w39rf”:{“id”:”w39rf”,”image”:””,”imageId”:””,”title”:”A.\tAtrial Septal Defect”},”wnj42″:{“id”:”wnj42″,”image”:””,”imageId”:””,”title”:”B.\tBicuspid Aortic Valve”,”isCorrect”:”1″},”q1x1x”:{“id”:”q1x1x”,”image”:””,”imageId”:””,”title”:”C.\tVentricular Septal Defect”}}}}}

{“questions”:{“y4n0w”:{“id”:”y4n0w”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Nicholas Houska, DO – University of Colorado. Children\u2019s Hospital Colorado \r\n\r\nA 12-year-old female with a history of repaired Tetralogy of Fallot during infancy presents for surgical pulmonary valve replacement. Due to coronary anatomy, transcatheter pulmonary valve implantation is not an option. Which type of surgical pulmonary valve replacement is associated with the HIGHEST incidence of infective endocarditis?”,”desc”:”EXPLANATION \r\n\r\nReconstruction of the right ventricular outflow tract with implantation of an extracardiac pulmonary-valved conduit may be necessary in patients with both acquired and congenital heart disease. Alternatively, the pulmonary valve may be replaced with a bioprosthetic or mechanical valve. Conduits used for this purpose include cryopreserved pulmonic or aortic homografts, Contegra conduits, and transcatheter pulmonary valves (Melody and Edwards SAPIEN). Homograft conduits have been used for the last 50-60 years, while Contegra conduit use began in the last 20-25 years. Contegra conduits are made of bovine jugular vein with a trileaflet venous valve. The Melody and Edwards SAPIEN valves are two types of percutaneously implanted pulmonary valves. The Melody valve is composed of bovine jugular vein with a trileaflet venous valve sutured into an expandable platinum stent. The Edwards SAPIEN valve is comprised of bovine pericardium that is shaped into a trileaflet valve and mounted onto an expandable cobalt-chromium frame. One large nationwide registry-based study that included all patients with at least one pulmonary valve replacement prior to 2018 by Stammnitz et al demonstrated that pulmonary valve replacement (PVR) with a bovine jugular vein valve (Contegra conduit or Melody valve) has the highest risk of infective endocarditis (IE) irrespective of mode of deployment, either surgical or percutaneous. In this study, the overall incidence of IE was 4.8% after a median follow up of 10 years per patient. Patients with a Contegra conduit had an incidence of IE of 5.4% while those with a homograft had an incidence of 1.3%. There was a 0% incidence of IE in patients with a mechanical valve or Edwards SAPIEN valve. The risk for IE was higher for surgically implanted Contegra grafts (HR, 5.62; 95% CI, 2.42\u201313.07; P<0.001) and transcatheter Melody Valves (HR, 7.81; 95% CI, 3.20\u201319.05; P<0.001) compared to homografts. The median time interval from PVR to infective endocarditis was 3 and 5 years for Contegra conduit and Melody valves respectively. The increased risk of IE with Contegra conduits and transcatheter Melody valves as compared to homograft conduits has been demonstrated in smaller studies as well. \r\n\r\n \r\nREFERENCES \r\nStammnitz C, Huscher D, Bauer UMM, et al. Nationwide registry\u2010based analysis of infective endocarditis risk after pulmonary valve replacement. JAHA<\/em>. 2022;11(5): e022231. \r\n\r\nHaas NA, Bach S, Vcasna R, et al. The risk of bacterial endocarditis after percutaneous and surgical biological pulmonary valve implantation. Int J cardiol<\/em>. 2018; 268:55-60. \r\n\r\nGr\u00f6ning M, Tahri NB, S\u00f8ndergaard L, Helvind M, Ersb\u00f8ll MK, Andersen H\u00d8. Infective endocarditis in right ventricular outflow tract conduits: a register-based comparison of homografts, Contegra grafts and Melody transcatheter valves. Eur J Cardiothorac Surg <\/em>.2019; 56(1):87-93.\r\n”,”hint”:””,”answers”:{“ppo92”:{“id”:”ppo92″,”image”:””,”imageId”:””,”title”:”A.\tHomograft conduit”},”x61h5″:{“id”:”x61h5″,”image”:””,”imageId”:””,”title”:”B.\tMechanical valve”},”6b9lm”:{“id”:”6b9lm”,”image”:””,”imageId”:””,”title”:”C.\tValved bovine jugular vein conduit (Contegra)”,”isCorrect”:”1″}}}}}

{“questions”:{“silxl”:{“id”:”silxl”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Melissa Colizza, MD – CHU Sainte-Justine, Montreal, Quebec \r\n\r\nA 4-year-old male with a history of hypoplastic left heart syndrome (HLHS) and previous bidirectional Glenn with extensive bilateral pulmonary artery reconstruction undergoes a fenestrated Fontan procedure. On post-operative day one, the blood pressure decreases gradually to 64\/32 from 92\/45 despite increased vasoactive support with epinephrine and vasopressin, and the lactate increases from 1.4 to 4.2 The Fontan pressure is 20 mmHg with a common atrial pressure of 7 mm Hg and an oxygen saturation of 94% in room air. What is the MOST likely cause of the hypotension?”,”desc”:”EXPLANATION \r\nEarly Fontan failure consists of low cardiac output with high Fontan pressure that remains refractory to medical therapy. In recent years, the risk of early Fontan failure in experienced centers varies from 2-6%. It is usually caused by residual defects along the Fontan pathway such as atrioventricular valve (AVV) regurgitation, inadequate pulmonary artery (PA) size or dysrhythmias. Other factors that are known to be associated with a high risk of Fontan failure include heterotaxy, dominant-right ventricle (RV) morphology, common AV valve, increased pre-operative pulmonary artery pressure (PAP), increased post-operative Fontan pressure, elevated left ventricular end-diastolic pressure (LVEDP), and prolonged cardiopulmonary bypass (CPB) and cross-clamp times. \r\n\tIn 1989, the concept of fenestration was introduced as a technique to preserve cardiac output, albeit at the expense of systemic oxygen desaturation, and to minimize the complications associated with high systemic venous pressures such as, pleural effusions, ascites, and lymphatic dysfunction. The fenestration has allowed for expanded Fontan candidacy, including patients previously deemed high-risk. Early reports demonstrated decreased length of hospital stay, leading to the widespread use of a Fontan fenestration in the 1990s. Its popularity waned in the face of undesirable long-term complications, including lower resting systemic oxygen saturation resulting in diminished exercise tolerance and higher risk for systemic thromboembolism. Despite being widely used, there is still much debate about the risks and benefits of fenestration. Two meta-analyses by Bouhout et al. and Li et al. have come to different conclusions. Bouhout et al. reported that the main benefits of a fenestration were lower PAP and decreased chest tube drainage. Li et al. described a lower burden of dysrhythmias. Both studies concluded that there was no significant difference in early mortality, need for Fontan takedown, length of hospital stay, or incidence of stroke or thrombosis. A retrospective study by Daley et al. demonstrated that patients with a fenestration had significantly lower survival, lower freedom from failing Fontan physiology and lower thromboembolic disease. However, the groups were overall unmatched; fenestrated patients had a higher incidence of HLHS, RV dominance, lateral tunnel Fontan, significant AVV regurgitation or AVV surgery, need for PA plasty, and higher mean PAP. These findings illustrate the challenge to objectively determine the benefits of Fontan fenestration since it is typically reserved for patients at higher risk for Fontan failure, which creates selection bias across studies. \r\n\r\n\r\nFontan failure can be categorized as circulatory failure or mechanical pump failure. Circulatory failure refers to the inability to maintain adequate pulmonary blood flow through the pulmonary vascular bed with an acceptable Fontan pressure. The pulmonary vascular bed is the most critical \u201cbottleneck\u201d, and successful Fontan circulation requires low pulmonary vascular resistance (PVR) and adequately sized pulmonary arteries. Mechanical pump failure relates to inability of the heart to meet systemic oxygen demand and may be secondary to systolic or diastolic dysfunction, dysrrhythmia, obstruction along the systemic vascular pathway or AVV regurgitation. Isolated systolic dysfunction remains fairly uncommon in the immediate post-operative period and should prompt investigation into an acute cause. It rarely causes profound cardiogenic shock unless the cardiac function is so poor that high atrial pressures prevent blood flow through the fenestration or through the pulmonary circulation. The child in the question has low cardiac output, low common atrial pressure and high Fontan pressures which would be consistent with circulatory failure. In the case of mechanical pump failure due to severe AVV regurgitation or systolic dysfunction, the common atrial pressure would likely be higher than 7 mm Hg. However, if the common atrial pressure remains lower than the Fontan pressure, shunting of desaturated blood through a patent fenestration is expected resulting in a systemic oxygen saturation ranging from of 70-80%. Shunting of desaturated blood is also expected in patients with a fenestrated Fontan and high pulmonary artery pressures secondary to hypoplastic pulmonary arteries or high pulmonary vascular resistance.\r\n\r\n\r\n\tPost-cardiopulmonary bypass vasoplegia is a type of distributive shock typically occurring within the first 24 hours post-operatively. It is characterized by hypotension, high cardiac output, and low systemic vascular resistance that is relatively resistant to vasopressors and fluids. Vasoplegia tends to occur in cases of long CPB\/cross-clamp times, and the pre-operative use of systemic vasodilators. It classically presents with hypotension requiring treatment with vasoactive medications in the absence of low mixed venous saturation or high lactate. Therefore, it is less likely in this patient. \r\n\r\nIn the above case, our patient is a high-risk Fontan due to the presence of a high fixed resistance to pulmonary blood flow secondary to hypoplastic pulmonary arteries (note the history of bilateral pulmonary artery reconstruction with likely residual pulmonary hypoplasia). The new finding of high Fontan pressures, low common atrial pressure, and high systemic saturation with evidence of a low cardiac output state points to an occluded fenestration. In this scenario, there is inadequate pulmonary blood flow through the lungs resulting in low cardiac output, and an absence of blood flow through the fenestration resulting in high systemic oxygen saturation given absent mixing of pulmonary venous return and systemic venous return in the common atrium. Although re-opening a fenestration is feasible in the cardiac catheterization lab, this may be associated with a high risk of systemic thromboembolism as the most likely cause of occlusion in the early post-operative period is a thrombus. Since most fenestrations are only 4 mm in diameter, reopening it may only have marginal benefits on such tenuous hemodynamics and further diagnostic evaluation, such as computed tomography with angiography or cardiac catheterization, may be needed. In the worst-case scenario, the Fontan may have to be taken down. \r\n\r\n\r\n\r\n \r\nREFERENCES \r\n\r\nGewillig M, Brown SC. The Fontan circulation after 45 years: update in physiology. Heart <\/em>.2016;102(14):1081-1086. doi: 10.1136\/heartjnl-2015-307467\r\n\r\nDesphpande SR, Bearl DW, Eghtesady P, et al. Clinical approach to vasoplegia in the transplant patient from the Pediatric Heart Transplant Society. Pediatr Transplant<\/em>. 2022; 26(8):e14392. doi: 10.1111\/petr.14392\r\n\r\nRochelson E, Richmond ME, LaPar DJ, Torres A, Anderson BR. Identification of Risk Factors for Early Fontan Failure. Semin Thorac Cardiovasc Surg.<\/em> 2020; 32(3):522-528. doi: 10.1053\/j.semtcvs.2020.02.018\r\n\r\nBouhout I, Ben-Ali W, Khalaf D, Raboisson MJ, Poirier N. Effect of Fenestration on Fontan Procedure Outcomes: A Meta-Analysis and Review. Ann Thorac Surg<\/em>. 2020; 109(5):1467-1474. doi: 10.1016\/j.athoracsur.2019.12.020\r\n\r\n\r\nLi D, Li M, Zhou X, An Q. Comparison of the fenestrated and non-fenestrated Fontan procedures: A meta-analysis. Medicine (Baltimore)<\/em>. 2019; 98(29):e16554. doi: 10.1097\/MD.0000000000016554 \r\n\r\n\r\nDaley M, Buratto E, King G, et al. Impact of Fontan Fenestration on Long-Term Outcomes: A Propensity Score-Matched Analysis. J Am Heart Assoc<\/em>. 2022;11(11):e026087. doi: 10.1161\/JAHA.122.026087\r\n\r\n”,”hint”:””,”answers”:{“cy049”:{“id”:”cy049″,”image”:””,”imageId”:””,”title”:”A. Obstructed fenestration”,”isCorrect”:”1″},”lhs5o”:{“id”:”lhs5o”,”image”:””,”imageId”:””,”title”:”B. Vasoplegia”},”zh0xi”:{“id”:”zh0xi”,”image”:””,”imageId”:””,”title”:”C. Severe atrioventricular valve regurgitation\r\n\r\n”}}}}}