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

{“questions”:{“m0xg1”:{“id”:”m0xg1″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Anna Hartzog MD and Chinwe Unegbu MD \u2013 Children\u2019s National Hospital \r\n\r\nA 4-day-old full term infant is diagnosed with Tetralogy of Fallot (TOF) with severe pulmonary stenosis. What is the MOST LIKELY reason to select a two-stage repair with an initial modified Blalock Taussig shunt (mBTS) instead of a complete repair with a transannular patch? \r\n\r\n”,”desc”:””,”hint”:””,”answers”:{“c7jk9”:{“id”:”c7jk9″,”image”:””,”imageId”:””,”title”:”A. Decreased need for transannular patch “},”utrdp”:{“id”:”utrdp”,”image”:””,”imageId”:””,”title”:”B. Improved long-term outcomes “},”7m71a”:{“id”:”7m71a”,”image”:””,”imageId”:””,”title”:”C. Institutional preference”,”isCorrect”:”1″},”b1wlo”:{“id”:”b1wlo”,”image”:””,”imageId”:””,”title”:”D. Decreased pulmonary artery distortion “}}}},”results”:{“y2qal”:{“id”:”y2qal”,”title”:””,”image”:””,”imageId”:””,”min”:”0″,”max”:”1″,”desc”:”Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. It is characterized by four distinct anatomic features described by Etienne Fallot in 1888 including the following: 1) anterior malalignment ventricular septal defect, 2) right ventricular outflow tract obstruction, 3) overriding aorta, and 4) right ventricular hypertrophy. The anterior malalignment of the conoventricular septum produces the spectrum of disease which can range in severity from an asymptomatic neonate to one that is severely cyanotic and has ductal-dependent physiology. The severity of the right ventricular outflow tract obstruction (RVOTO) determines the degree of cyanosis. Most commonly, cyanosis is mild at birth and gradually progresses with age as there is an increase in infundibular hypertrophy. By six to twelve months of life, the cyanosis tends to be significant. A smaller percentage of patients with TOF and pulmonary stenosis (PS) have marked cyanosis soon after birth. In this population, the RVOTO is often secondary to a hypoplastic pulmonary valve annulus and the cyanosis is constant because of the fixed nature of the obstruction to pulmonary blood flow. \r\n\r\nTraditionally, there have been two surgical approaches to Tetralogy of Fallot with pulmonary stenosis including primary complete repair versus a two-stage repair with an aortopulmonary shunt followed by a complete repair either with a transannular patch or a valve sparing procedure. At present, the ideal age for complete correction of TOF remains elusive and is highly institution dependent. Historically, the approach to a neonate or infant with TOF has been to wait for surgical repair until symptoms develop or until the infant was older. The morbidity and mortality of the operation was thought to be less in an older patient. \r\n\r\nAn early primary repair restores a normal circulation, which can diminish the deleterious physiologic effects of TOF to the heart, lungs, brain and other organ systems. Studies have shown that normalizing pulmonary arterial flow early optimizes pulmonary angiogenesis and alveolar development. Additionally, due to the unrestrictive anterior malalignment VSD, the right ventricle is exposed to systemic pressure resulting in right ventricular hypertrophy and decreased compliance. There is some evidence that left ventricular function is compromised as well when repair is delayed. There is a lower incidence of ventricular arrhythmias among children repaired at younger ages. An additional benefit of primary repair is the avoidance of aortopulmonary shunt related complications such as pulmonary artery distortion, shunt thrombosis, congestive heart failure, and\/or pulmonary vascular disease. Thus, answer choice B and D are incorrect. At present, there is essentially no contraindication to early primary repair. Historically, indications for delayed repair include an anomalous coronary artery crossing the right ventricular outflow tract, hypoplastic or discontinuous pulmonary arteries, and multiple VSDs. \r\n\r\n\r\nDespite success with early primary surgical repair of TOF, a two-stage repair remains favored at many institutions. Thus, answer choice C is correct. This is primarily the result of institutional culture, experience, and outcomes. An additional reason to delay complete repair in favor of two-stage repair revolves around the physiologic sequelae of a transannular patch over time, which includes increased ventricular dimensions, decreased ventricular function, decreased exercise capacity, arrhythmias, heart failure, and sudden cardiac death. However, there is insufficient evidence to support the idea that a two-stage repair decreases the risk of later pulmonary valve replacement. The largest published series describing late-phase events in adults with repaired TOF demonstrated that the risk of later reoperation is independent of the type of initial repair. Likewise, there is no evidence to suggest that initial palliation with an aortopulmonary shunt results in a decreased incidence of later complete repair with a transannular patch. Thus, answer choice A is incorrect. \r\n\r\n\r\nAl Habib et al. analyzed contemporary patterns of management of TOF\/PS using The Society of Thoracic Surgeons database and demonstrated that procedure type in neonates was equally divided between primary repair and a two-stage approach. In addition, use of a transannular patch was the most prevalent surgical technique for both primary repair and for a 2-stage repair. The discharge mortality from TOF repair in neonates was not significantly different between palliation (6.2%) and primary repair (7.8%). Thus, answer choice B is incorrect. Kanter et al. examined outcomes in neonates with symptomatic TOF who underwent either a primary repair or a two-stage repair and found equivalent mortality rates. Additionally, the study demonstrated that shunted patients had fewer transannular patch repairs but this has not been a consistent finding across studies. Antegrade pulmonary blood flow is the primary stimulus for growth of right ventricular outflow tract structures and thus a palliative aortopulmonary shunt would perpetuate reduced pulmonary flow. Thus, the expectation would be that the pulmonary valve would become smaller with time in patients with an aortopulmonary shunt and increase the need for a transannular patch. Nonetheless, the debate about the effect of early primary repair with a transannular patch on the growth of the pulmonary valve annulus remains a hot topic. \r\n\r\nReferences \r\n\r\n1.\tBarratt-Boyes BG, Neutze JM. Primary repair of Tetralogy of Fallot in infancy using profound hypothermia with circulatory arrest and limited cardiopulmonary bypass: a comparison with conventional two stage management. Ann Surg<\/em>. 1973; 178: 406\u2013411. \r\n\r\n2.\tCastaneda AR, Freed MD, Williams RG, Norwood WI. Repair of Tetralogy of Fallot in infancy: early and late results. J Thorac Cardiovasc Surg<\/em>. 1977; 74: 372\u2013381. \r\n\r\n3.\tDi Donato RM, Jonas RA, Lang P, Rome JJ, Mayer JE Jr, Castaneda AR. Neonatal repair of tetralogy of Fallot with and without pulmonary atresia. J Thorac Cardiovasc Surg<\/em>. 1991; 101(1):126-137. PMID: 1986154. \r\n\r\n4.\tSullivan ID, Presbitero P, Gooch VM, Arura E, Deanfield JE. Is ventricular arrhythmia in repaired tetralogy of Fallot an effect of operation or a consequence of the course of the disease? A prospective study. Br Heart J<\/em>. 1987; 58: 40\u201344.\r\n\r\n5.\tHegerty A, Anderson RH, Deanfield JE. Myocardial fibrosis in tetralogy of Fallot: effect of surgery or part of the natural history? Br Heart J<\/em>. 1988; 59: 123. \r\n\r\n6.\tJonas RA. Early primary repair of tetralogy of Fallot. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu<\/em>. 2009: 39-47.\r\n\r\n7.\tParry AJ, McElhinney DB, Kung GC, Reddy M, Brook MM, Hanley FL. Elective Primary Repair of Acyanotic Tetralogy of Fallot in Early Infancy: Overall Outcome and Impact on the Pulmonary Valve. J Am Coll Cardiol<\/em>. 2000; 36: 2279\u20132283. \r\n\r\n8.\tKirklin JW, Blackstone EH, Pacifico AD, Brown RN, Bargeron LM Jr. Routine primary repair vs two stage repair of tetralogy of Fallot. Circulation<\/em>. 1979; 60: 373\u2013386. \r\n\r\n9.\tVobecky SJ, Williams WG, Trusler GA, et al. Survival analysis of infants under age 18 months presenting with tetralogy of Fallot. Ann Thorac Surg<\/em>. 1993; 56: 944\u2013949. \r\n\r\n\r\n10.\tVan Arsdell GS, Maharaj GS, Tom J et al. What is the Optimal Age for Repair of Tetralogy of Fallot? Circulation<\/em>. 2000;102:Iii-123\u2013129. \r\n\r\n11.\tGladman G, McCrindle BW, Williams WG, et al. The modified Blalock-Taussig shunt: clinical impact and morbidity in Fallot\u2019s tetralogy in the current era. J Thorac Cardiovasc Surg<\/em>. 1997; 114: 25\u201330. \r\n\r\n12.\tUva MS, Chardigny C, Galetti L, et al. Surgery for tetralogy of Fallot at less than six months of age. Is palliation \”old-fashioned\u201d? Eur J Cardiothorac Surg<\/em>. 1995; 9(8): 453\u2013460. \r\n\r\n13.\tLee CH, Kwak JG, Lee C. Primary repair of symptomatic neonates with tetralogy of Fallot with or without pulmonary atresia. Korean J Pediatr<\/em>. 2014; 57(1): 19-25. doi: 10.3345\/kjp.2014.57.1.19. \r\n\r\n14.\tAl Habib HF, Jacobs JP, Mavroudis C, et al. Contemporary patterns of management of tetralogy of Fallot: data from the Society of Thoracic Surgeons Database. Ann Thorac Surg<\/em>. 2010; 90(3): 813-819. \r\n\r\n15.\tKanter KR, Kogon BE, Kirshbom PM, Carlock PR. Symptomatic neonatal tetralogy of Fallot: repair or shunt? Ann Thorac Surg<\/em>. 2010; 89(3): 858-863. \r\n\r\n16.\tGuyton RA, Owens JE, Waumett JD, Dooley KJ, Hatcher CR Jr, Williams WH. The Blalock-Taussig shunt. Low risk, effective palliation, and pulmonary artery growth. J Thorac Cardiovasc Surg<\/em>. 1983; 85(6): 917-922. \r\n\r\n17.\tPigula FA, Khalil PN, Mayer JE, del Nido PJ, Jonas RA. Repair of Tetralogy of Fallot in Neonates and Young Infants. Circulation<\/em>. 1999; 100: II-157\u2013161.\r\n\r\n\r\n”,”redirect_url”:””}}}

{“questions”:{“e6xx6”:{“id”:”e6xx6″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Anna Hartzog MD\u2013 Children\u2019s National Hospital, Chinwe Unegbu MD \u2013 Children\u2019s National Hospital \r\n\r\nA three-year-old male child with a history of heterotaxy and an unbalanced atrioventricular canal palliated with an extracardiac Fontan presents for cardiac catheterization. The catheterization angiograms demonstrate large collateral blood vessels from the bilateral internal mammary arteries. Which of the following is the MOST appropriate reason to use particle embolization instead of coil embolization to occlude collateral blood vessels?”,”desc”:””,”hint”:””,”answers”:{“a1piz”:{“id”:”a1piz”,”image”:””,”imageId”:””,”title”:”A. Decreased risk of systemic embolization”},”vu68v”:{“id”:”vu68v”,”image”:””,”imageId”:””,”title”:”B. More effective proximal occlusion of the feeder vessel”},”hnnjv”:{“id”:”hnnjv”,”image”:””,”imageId”:””,”title”:”C. Future catheterization of the feeder vessel is not compromised”,”isCorrect”:”1″},”1qtus”:{“id”:”1qtus”,”image”:””,”imageId”:””,”title”:”D. More effective occlusion of larger diameter feeder vessels”}}}},”results”:{“uwn5h”:{“id”:”uwn5h”,”title”:””,”image”:””,”imageId”:””,”min”:”0″,”max”:”1″,”desc”:”Aortopulmonary collaterals (APCs) are common in patients with single ventricle physiology,\r\noccurring in up to two-thirds of patients after the bidirectional Glenn procedure and one-half of\r\npatients after the Fontan procedure. These collaterals provide a source of blood from the\r\nsystemic arterial circulation to the pulmonary circulation resulting in recirculation of oxygenated\r\nblood through the pulmonary circulation and volume overload of the single ventricle. The\r\nmechanism as to how and the reason why collaterals develop is not understood completely.\r\nSome of the proposed triggers of APC formation include hypoxemia-induced angiogenesis,\r\nchronic chest wall inflammation, and small pulmonary artery (PA) size. The benefits provided by\r\naortopulmonary collateral blood supply include improved systemic oxygenation and pulmonary\r\nartery development and growth. However, the negative sequelae of volume overload to the single\r\nventricle includes single ventricle dilation and dysfunction, heart failure, and ineffective\r\npulmonary blood flow outweigh the potential benefits. Early studies did not demonstrate a\r\nbenefit of coiling APCs in patients prior to the Fontan nor a benefit in length of hospital stay\r\nfollowing the Fontan palliation. However, more recent studies have demonstrated that\r\nsignificant collateral burden is associated with prolonged pleural effusions, longer intensive care\r\nunit stays, and overall longer hospital stays. Studies have also demonstrated that pre-Fontan coil\r\nembolization has been associated with improved preoperative hemodynamics. \r\n\r\nTranscatheter thrombotic coil embolization has traditionally been utilized to occlude APCs as an\r\nalternative to surgical exposure and ligation. Often these collaterals are difficult to locate and\r\nsurgically transected due to their location which could potentially prolong operative time and\r\nlead to increased blood loss. As such, transcatheter occlusion of collaterals in the cardiac\r\ncatheterization lab has proven to be an advantageous alternative. Coils are often composed of\r\nsteel or platinum and are sometimes embedded with fibers that promote thrombosis. They are\r\navailable in many different diameters and lengths. They serve to provide mechanical occlusion\r\nand promote occlusion of collaterals through thrombosis. Coils are typically inserted into\r\nproximal normal-caliber systemic arteries that supply the collateral vessels, which serves to limit\r\ncollateral blood flow, left to right shunting, and volume overload. However, coil embolization of\r\nthe proximal systemic arterial supply does not occlude the collateral vessels themselves. Thus,\r\nthe collateral vessels are left intact for possible future vascular supply from either the same or\r\nnew \u201cfeeding\u201d blood vessels. Additionally, placement of coils into proximal systemic arteries\r\ndoes prohibit further access to those particular vessels during future cardiac catherization\r\nprocedures. \r\n\r\nParticle embolization is a newer technique utilized for APC occlusion that may provide more\r\nefficient distal embolization by targeting smaller arteries and more distal arterioles. Thus larger\r\n\u201cfeeding\u201d arteries are left intact, allowing future access with catheterization. The most common\r\nmaterials for particle embolization include polyvinyl alcohol (PVA) microparticles and tris-acryl\r\ngelatin microspheres (TAGM). APC occlusion is due to thrombus formation around the PVA\r\nparticles. While PVA particles themselves are non-absorbable, surrounding clot may dissolve\r\nafter a few weeks, and the vessels may recanalize. Due to the small size of both PVA and TAGM\r\nparticles, there is a significant risk of systemic embolization, especially if deployed into larger\r\ncaliber vessels. Systemic embolization into a vessel supplying the central nervous system can\r\nlead to stroke and spinal cord injury. Particular vessels to avoid include the vertebral and carotid\r\narteries as well as the artery of Adamkiewicz. It is imperative to perform frequent neurovascular\r\nexams in the initial post-catheterization period. \r\n\r\nChoice C is the correct answer; particle embolization occludes vessels more distally and does not\r\nocclude the proximal \u201cfeeding\u201d vessel. Choice A is incorrect as particle embolization poses a\r\nhigher risk of systemic embolization due to small particle size. Choice B and D are incorrect\r\nbecause coil embolization is more effective for occlusion of more proximal and larger diameter\r\nvessels. \r\n\r\nReferences \r\n1. Prakash, A. Significance of systemic to pulmonary artery collaterals in single ventricle\r\nphysiology: new insights from CMR imaging. Heart<\/em>. 2012; 98(12): 897-899. \r\n2. Banka P, Sleeper LA, Atz AM, et al. Practice Variability and Outcomes of Coil\r\nEmbolization of Aortopulmonary Collaterals Prior to Fontan Completion: A Report from\r\nthe Pediatric Heart Network Fontan Cross-Sectional Study. Am Heart J<\/em>. 2011; 162(1):\r\n125\u2013130. \r\n3. Latus H, Gummel K, Diederichs T, et al. Aortopulmonary Collateral Flow Is Related to\r\nPulmonary Artery Size and Affects Ventricular Dimensions in Patients after the Fontan\r\nProcedure. PLoS One<\/em>. 2013; 8(11): e81684. \r\n4. Batlivala S, Briscoe W, and Ebeid M. Particle embolization of systemic-to-pulmonary\r\ncollateral artery networks in congenital heart disease: Technique and special\r\nconsiderations. Ann Pediatr Cardiol<\/em>. 2018; 11(2): 181-186. \r\n5. O\u2019Bryne M, Schidlow D. Durable Benefit of Particle Occlusion of Systemic to\r\nPulmonary Collaterals in Select Patients After Superior Cavopulmonary Connection.\r\nPediatr Cardiol<\/em>. 2018; 39(2): 245-253. \r\n6. Dori Y, Glatz AC, Hanna BD, et al. Acute Effects of Embolizing Systemic-to-Pulmonary\r\nArterial Collaterals on Blood Flow in Patients With Cavopulmonary Connections: A Pilot\r\nStudy. Circ Cardiovasc Interv<\/em>. 2013; 6(1): 101-106. \r\n7. Sim J, Aleijos J, and Moore J. Techniques and Applications of Transcatheter\r\nEmbolization Procedures in Pediatric Cardiology. J Interv Cardiol<\/em>. 2003; 6(5): 425-448. \r\n\r\n\r\n”,”redirect_url”:””}}}

{“questions”:{“ld468”:{“id”:”ld468″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Anna Hartzog MD\u2013 Children\u2019s National Hospital, Chinwe Unegbu MD \u2013 Children\u2019s National Hospital \r\n\r\nA 3-month-old male with Tetralogy of Fallot (TOF) with worsening cyanosis presents for surgical repair with infundibular muscle bundle resection and a transannular patch. Preoperatively, the patient has been on propranolol and his baseline heart rate is 120. Prior to separation from bypass, dopamine is started at 10 mcg\/kg\/min, the rectal temperature is 35.5 degrees Celsius, and the magnesium level is 2.1 mg\/dL. Upon separation from cardiopulmonary bypass (CPB), junctional ectopic tachycardia (JET) is noted with hemodynamic instability. What is the MOST LIKELY contributing factor to JET in this patient?\r\n”,”desc”:””,”hint”:””,”answers”:{“y7z7y”:{“id”:”y7z7y”,”image”:””,”imageId”:””,”title”:”A. Preoperative heart rate “},”64v8r”:{“id”:”64v8r”,”image”:””,”imageId”:””,”title”:”B. Intraoperative magnesium level”},”fab9v”:{“id”:”fab9v”,”image”:””,”imageId”:””,”title”:”C. Intraoperative inotropic requirement”,”isCorrect”:”1″},”70f49″:{“id”:”70f49″,”image”:””,”imageId”:””,”title”:”D. Rewarming target temperature”}}}},”results”:{“3cpjt”:{“id”:”3cpjt”,”title”:””,”image”:””,”imageId”:””,”min”:”0″,”max”:”1″,”desc”:”Junctional ectopic tachycardia (JET) is the most common tachyarrhythmia in the postoperative period in children undergoing congenital heart surgery. The reported incidence following pediatric cardiac surgery ranges widely from 2-22%, which is due to differences in study design and the diversity of cardiac lesions represented in those studies. \r\n\r\nCongenital heart defects that are known to be major contributors to postoperative JET include ventricular septal defect (VSD), Tetralogy of Fallot (TOF), and complete atrioventricular canal (CAVC). The incidence of JET is greater when the surgical intervention is in close proximity to the atrioventricular (AV) node and bundle of His, as is the case with TOF and CAVC repair. TOF repair is widely recognized as the surgical procedure most likely to be associated with the development of postoperative JET. The reported incidence of JET following TOF repair varies from 4 to 37% in the literature. A 2018 study by Paluszek et al. reported the incidence of JET in pediatric patients following TOF repair to be 13.3%. \r\n\r\n\r\nEarly postoperative JET typically occurs within the first forty-eight hours after pediatric cardiac surgery and is defined as a narrow complex tachycardia with a rate of \u2265 170 bpm. JET originates from the atrioventricular (AV) node or AV junction, which includes the bundle of His. There is often AV dissociation resulting in the ventricular rate exceeding the atrial rate but sometimes there is 1:1 retrograde ventriculoatrial conduction. JET typically manifests with a narrow QRS complex; however, if a bundle branch block is present, then the QRS complex may be wide. The exact etiology of JET is unknown; however, many hypothesize that JET may be the result of direct mechanical trauma (ie surgical sutures) or indirect stretch injury with or without edema to the conduction system which then precipitates automaticity of the AV node\/bundle of His. \r\n\r\n\r\nDespite generally being a self-limiting condition, JET can be associated with postoperative hemodynamic instability and morbidity due to hemodynamic deterioration secondary to extreme tachycardia, loss of AV synchrony, and compromised ventricular filling. In particular, the combination of JET and depressed myocardial function may result in a low cardiac output state and cardiogenic shock. \r\n\r\n\r\nRisk factors for postoperative JET include an increased baseline preoperative heart rate, cyanotic spells, non-use of beta-blockers in the preoperative period, low intraoperative magnesium and calcium levels, prolonged cardiopulmonary bypass (CPB) and\/or aortic cross clamp times, hypothermic circulatory arrest, increased complexity of the surgical procedure, and use of high dose inotropes. Postoperative JET is also associated with a younger age at the time of operation and lower body weight. Younger patients presenting for surgical repair have smaller hearts that are more prone to mechanical or stretch related injury of the conduction system. Both postoperative inotropic score and dopamine use have been independently associated with the occurrence of postoperative JET. This suggests that JET may be triggered by the arrhythmogenic properties of dopamine. \r\n\r\n\r\nInterventions known to reduce the occurrence of JET after pediatric cardiac surgery include minimization of CPB and aortic cross clamp time, correction of electrolyte imbalances especially magnesium and calcium, use of magnesium sulfate on CPB, optimization\/titration of inotropic support with the goal of minimizing exogenous catecholamines, correction of intravascular volume, avoidance of hyperthermia, and adequate use of sedatives and analgesics. Some patients with JET require external pacing to restore AV synchrony. Many antiarrhythmics have been used in the management of JET, including but not limited to digoxin, sotalol, procainamide, and amiodarone. No single antiarrhythmic has been found to be superior. Typically, the antiarrhythmic initiated is simply a matter of institutional preference. \r\n\r\n\r\nIn this question stem, the most likely contributing factor to JET is the use of dopamine. The use of propranolol preoperatively suggests heart rate control and should be preventative against JET. Likewise, the magnesium level prior to separation from CPB was within normal limits and would be preventative as well. The rewarming target temperature of 35.5 is appropriately low and preventative to hyperthermia induced JET. \r\n\r\n\r\nReferences \r\n\r\n1.\tAl-Sofyani KA, Jamalaldeen RI, Abusaif SM, Elassal AA, Al-Radi OO. The prevalence and outcome of junctional ectopic tachycardia in pediatric cardiac surgery: Journal of the Egyptian Society of Cardio-Thoracic Surgery<\/em>. 2017; 25(2): 128-132. \r\n\r\n2.\tPaluszek C, Brenner P, Pichlmaier M, et al. Risk Factors and Outcome of Post Fallot Repair Junctional Ectopic Tachycardia (JET): World J Pediatr Congenit Heart Surg<\/em>. 2019; 10(1): 50-57. doi: 10.1177\/2150135118813124. PMID: 30799715. \r\n\r\n\r\n3.\tDodge-Khatami A, Miller OI, Anderson RH, et al. Surgical substrates of postoperative junctional ectopic tachycardia in congenital heart defects. J Thorac Cardiovasc Surg<\/em>. 2002; 123(4): 624-630. \r\n\r\n4.\tIsmail MF, Arafat AA, Hamouda TE, et al. Junctional ectopic tachycardia following tetralogy of fallot repair in children under 2 years. J Cardiothorac Surg<\/em>. 2018; 13(1): 60. doi:10.1186\/s13019-018-0749-y \r\n\r\n5.\tManrique AM, Arroyo M, Lin Y, et al. Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: a randomized controlled study. J Thorac Cardiovasc Surg<\/em>. 2010; 139: 162-169. \r\n\r\n6.\tEl Amrousy D, Elshehaby W, Elfeky W, Elshmaa N. Safety and efficacy of prophylactic amiodarone in preventing early junctional ectopic tachycardia (JET) in children after cardiac surgery and determination of its risk factor. Pediatr Cardiol<\/em>. 2016; 37: 734\u2013739.\r\n\r\n\r\n\r\n\r\n\r\n”,”redirect_url”:””}}}

{“questions”:{“3ictj”:{“id”:”3ictj”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Sana Ullah, MB ChB, FRCA \u2013 Children\u2019s Medical Center, Dallas\r\n\r\nA 6-year-old male child with a history of Kawasaki disease is undergoing pharmacological stress cardiac magnetic resonance imaging (MRI) with adenosine. Which of the following adenosine receptors is MOST LIKELY<\/em> associated with coronary vasodilation?\r\n”,”desc”:””,”hint”:””,”answers”:{“81vr6”:{“id”:”81vr6″,”image”:””,”imageId”:””,”title”:”A.\tA1″},”fv5xu”:{“id”:”fv5xu”,”image”:””,”imageId”:””,”title”:”B.\tA2A”,”isCorrect”:”1″},”ptx0g”:{“id”:”ptx0g”,”image”:””,”imageId”:””,”title”:”C.\tA2B”},”mcrw6″:{“id”:”mcrw6″,”image”:””,”imageId”:””,”title”:”D.\tA3″}}}},”results”:{“5colx”:{“id”:”5colx”,”title”:””,”image”:””,”imageId”:””,”min”:”0″,”max”:”1″,”desc”:”Adenosine is a naturally occurring purine nucleoside base that exerts varying effects via four different purinergic adenosine receptors. These various effects include the following: \r\n–A1 receptor activation in the atrioventricular node decreases conduction and produces a slowing of the heart rate. This effect is utilized in the diagnosis and treatment of certain supraventricular tachycardias particularly during electrophysiology (EP) studies.\r\n–A2A receptor activation in vascular smooth muscle, including the coronary arteries, produces vasodilation and decreases systemic blood pressure. \r\n–A2B and A3 receptor activation in bronchial smooth muscles causes bronchoconstriction. \r\n\r\n\r\nPharmacologic stress cardiac magnetic resonance imaging (MRI) is used for the initial evaluation and subsequent follow-up of pediatric patients with coronary abnormalities. Coronary abnormalities may occur in patients with a history of Kawasaki disease or perhaps in patients who have had surgical reimplantation of the coronary arteries, which may occur during the arterial switch operation or in patients with anomalous origins of coronary arteries. The principle behind pharmacological stress cardiac MRI is to produce maximal coronary vasodilation in \u201cnormal\u201d vessels, thereby producing a \u201csteal\u201d phenomenon in areas of myocardium supplied by the diseased vessels. These potentially ischemic regions can then be visualized by the administration of gadolinium contrast. \r\n\r\n\r\nAlthough protocols may vary slightly, a typical adenosine stress MRI involves the administration of adenosine as an infusion at 140 micrograms per kilogram per minute (mcg\/kg\/min) for a total of six minutes. At the three-minute time point, gadolinium contrast is given via a separate intravenous line. There is usually a modest increase in heart rate and a slight decrease in blood pressure. Non-sedated patients may experience nausea, flushing or chest pain. Due to a short half-life of less than 10 seconds, the effects of adenosine dissipate very quickly after discontinuing the infusion. \r\n\r\n\r\nAdenosine is contraindicated or extreme caution is warranted in certain patient groups including those with severe asthma or reactive airway disease, second or third degree heart block or sinus node dysfunction in the absence of a pacemaker, or in patients with unstable angina or acute coronary syndrome. \r\n\r\n\r\nMethylxanthine medications such as aminophylline, theophylline and caffeine antagonize adenosine binding at the A2A receptor and can reduce the coronary vasodilatory effects. In the case of serious adverse side effects, intravenous aminophylline can be administered as an antidote. Patients are typically advised to avoid caffeine-containing foods and beverages for at least 12 or preferably 24 hours before the test. \r\n\r\nRegadenoson is an alternative adenosine receptor agonist with more selectivity at the A2A receptor. Due to its selective nature, regadenoson is a more potent coronary vasodilator with a more prolonged duration of action. It is administered as an intravenous bolus and, therefore, there is no need for an additional intravenous line to administer gadolinium contrast. The peak coronary vasodilatory effect occurs after approximately two minutes, but the effect may last beyond thirty minutes due to its tri-phasic elimination kinetics. This may be disadvantageous in the case of serious side effects. Side effects may be uncommon due to receptor selectivity but similar in characteristic to those of adenosine. The cost of regadenoson is much higher than adenosine. \r\n\r\n\r\nReferences\r\n\r\n\r\n1)\tLayland J, Carrick D, Lee M, Oldroyd K, Berry C. Adenosine: Physiology, pharmacology, and clinical applications. J Am Coll Cardiol Intv<\/em>. 2014; 7: 581-591. \r\n\r\n2)\tFares M, Critser PJ, Arruda MJ, et al. Pharmacologic stress cardiovascular magnetic resonance in the pediatric population: A review of the literature, proposed protocol, and two examples in patients with Kawasaki disease. Congenit Heart Dis<\/em>. 2019; 14: 1166-1175.\r\n\r\n3)\tDoan TT, Wilkinson JC, Loar RW, Pednekar AS, Masand PM, Noel C. Regadenoson stress perfusion cardiac magnetic resonance imaging in children with Kawasaki disease and coronary artery disease. Am J Cardiol<\/em> 2019; 124: 1125-1132.”,”redirect_url”:””}}}

{“questions”:{“z49yi”:{“id”:”z49yi”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Sana Ullah, MB ChB, FRCA \u2013 Children\u2019s Medical Center, Dallas TX\r\n\r\nWhat is the MOST COMMON syndrome associated with pulmonary arteriovenous malformations ?\r\n\r\n”,”desc”:””,”hint”:””,”answers”:{“cye57”:{“id”:”cye57″,”image”:””,”imageId”:””,”title”:”A.\tScimitar syndrome”},”imdso”:{“id”:”imdso”,”image”:””,”imageId”:””,”title”:”B.\tOsler-Weber-Rendu syndrome”,”isCorrect”:”1″},”vlz1s”:{“id”:”vlz1s”,”image”:””,”imageId”:””,”title”:”C.\tKartagener\u2019s syndrome”},”vd63t”:{“id”:”vd63t”,”image”:””,”imageId”:””,”title”:”D.\tAlagille syndrome”}}}},”results”:{“9wcta”:{“id”:”9wcta”,”title”:””,”image”:””,”imageId”:””,”min”:”0″,”max”:”1″,”desc”:”Pulmonary arteriovenous malformations (AVMs) are structurally abnormal blood vessels which form direct communications between the pulmonary arterial and pulmonary venous circulations, producing a right-to-left shunt bypassing the alveolar gas exchange regions and the normal filtering functions of the lungs. The most common cause of pulmonary AVMs is Osler-Weber-Rendu syndrome, which is also known as Hereditary Hemorrhagic Telangiectasia (HHT). Osler-Weber-Rendu is inherited in an autosomal dominant manner and affects approximately 1 in 5,000 to 8,000 people. In addition to AVMs, smaller telangiectatic vessels that are prone to bleeding are frequently found in nasal, mucocutaneous, hepatic, gastrointestinal and cerebral vascular beds. \r\n\r\nPulmonary AVMs can also develop after surgical palliation with the bidirectional cavopulmonary shunt and produce significant systemic desaturation. The purported mechanism is due to the lack of a \u201chepatic factor\u201d that bypasses the pulmonary circulation after the bidirectional cavopulmonary shunt. Once the hepatic venous return is redirected back into the pulmonary circulation after Fontan completion, the pulmonary AVMs generally regress over a period of weeks to months. \r\n\r\n\r\nThe major clinical manifestations of pulmonary AVMs are recurrent bleeding manifesting as hemoptysis or hemothorax, systemic desaturation due to right-to-left shunting, ischemic strokes due to paradoxical thromboembolism, and cerebral abscesses resulting from bacteria in the blood that bypasses the filtering mechanism of the lungs. There is also an increased risk of pregnancy-related deaths in pregnant women with pulmonary AVMs. A rare but interesting phenomenon as a result of pulmonary AVMs is platypnea-orthodeoxia, which is best described as systemic desaturation and increased shortness of breath on standing up but improvement on lying flat. This is because most pulmonary AVMs are in the basal regions of the lungs thereby increasing the right-to-left shunt due to increased blood flow on assuming the upright posture. \r\n\r\n\r\nComputed tomography of the chest is the gold-standard for diagnosis of pulmonary AVMs and offers better resolution than MRI. Contrast echocardiography using agitated saline injected into an arm vein and imaging the left side of the heart can also be used, but it lacks specificity even though it is highly sensitive. Transcatheter embolization is recommended for treatment of all pulmonary AVMs that are amenable to vessel access. \r\n\r\n\r\nScimitar syndrome is a rare variant of partial anomalous pulmonary venous return of a portion or the entirety of the right lung to the inferior vena cava. The abnormal venous channel forms a characteristic curved shadow on chest x-ray along the right heart border which resembles a sword known as a scimitar. Associated abnormalities include hypoplasia of the right lung, secondary dextroposition of the heart, and pulmonary sequestration of portions of the right. The sequestered lung does not take part in gas exchange and is prone to recurrent bleeding and infection. Management of Scimitar Syndrome is largely determined by the degree of volume overload to the heart and associated cardiac anomalies. Lung segments affected by sequestration may need to be resected. \r\n\r\n\r\nKartagener\u2019s syndrome is an autosomal recessive disorder characterized by primary ciliary dyskinesis resulting in a triad of situs inversus totalis, chronic sinusitis, and bronchiectasis. \r\n\r\n\r\nAlagille syndrome is an autosomal dominant disorder consisting of bile duct paucity and cholestasis, characteristic triangular facies, widespread vascular anomalies and congenital heart disease. The congenital heart disease often manifests as peripheral pulmonary arterial stenosis or hypoplasia, pulmonary valve stenosis, and\/or Tetralogy of Fallot. Treatment of pulmonary arterial stenosis often requires a combination of surgical and transcatheter based techniques. Approximately 15% of patients eventually develop liver failure requiring transplantation. Many of these patients harbor a mutation in the JAG1 gene. \r\n\r\n\r\n\r\nReferences\r\n\r\n\r\n1.\t Shovlin CL. Pulmonary Arteriovenous Malformations. Am J Respir Crit Care Med<\/em>. 2014; 190(11): 1217-1228. \r\n\r\n2.\t Vida VL, Guariento A. A sword threatening the heart: The scimitar syndrome. JCTVS Techniques<\/em>. 2020; 1: 75-80. \r\n\r\n3.\t Tretter JT, McElhinney DB. Cardiac, Aortic, and Pulmonary Vascular Involvement in Alagille Syndrome. 2018. In: Kamath B., Loomes K. (eds) Alagille Syndrome. Springer, Cham. https:\/\/doi.org\/10.1007\/978-3-319-94571-2_6\r\n\r\n4.\t Kamath BM, Spinner NB, Emerick KM, et al. Vascular anomalies in Alagille syndrome: A significant cause of morbidity and mortality. Circulation<\/em>. 2004; 109:1354-1358.\r\n”,”redirect_url”:””}}}