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

{“questions”:{“hng79”:{“id”:”hng79″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:”https:\/\/ccasociety.org\/wp-content\/uploads\/2025\/10\/CCAS-102-QOW-Pic-1.jpg”,”imageId”:”9113″,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Kaitlin M. Flannery, MD, MPH – Stanford University AND Catherine Dietrich, MD – Stanford University \r\nA 5kg, 4-month-old infant with feeding intolerance and failure to thrive is noted to have a murmur on pediatrician follow up visit. A 4-chamber view of his transthoracic echocardiogram is shown below. What is the MOST LIKELY diagnosis identified in this image?”,”desc”:”EXPLANATION \r\nCor triatriatum (from the Latin for a \u201cheart with three atria\u201d) is a rare cardiac anomaly that results from abnormal septation of either the right (dexter \u2013 from the Latin for \u201cright-sided or right-handed\u201d) or left (sinister \u2013 from the Latin for \u201cleft-sided or left-handed\u201d) atrium. It occurs in less than 0.1% of all congenital heart disease. In classic cor triatriatum sinister (CTS), which was present in the patient above, a fibromuscular membrane divides the proximal atrium, which accepts pulmonary venous return, from the distal atrium which contains the atrial appendage and mitral valve. The membrane may be complete, incomplete, or fenestrated. The severity of the membrane gradient, and presence or absence of other cardiac anomalies, will determine the age and status at presentation.^{1<\/sup> \r\n \r\n\r\nCTS symptoms and management emulate that of mitral stenosis. Restriction of flow across the membrane results in elevated left atrial pressure which leads to elevated pulmonary venous pressure and pulmonary edema. The elevated pulmonary venous pressure will cause elevated pulmonary arterial pressure that can become permanent if left untreated. High left atrial pressure can result in left atrial dilation increasing risk for atrial arrhythmias and thrombus formation. If the flow gradient significantly limits left ventricular filling, a low cardiac output state may develop.1<\/sup> \r\n\r\nInduction of anesthesia for surgical correction requires maintenance of preload with judicious fluid administration, maintenance of sinus rhythm and avoidance of tachycardia to allow ventricular filling, and avoidance of increases in pulmonary vascular resistance (PVR) that will put additional strain on the right ventricle. Prior to surgical removal of the membrane, therapies that decrease PVR should be limited as they might cause pulmonary congestion. After removal of the membrane, PVR-lowering therapies can be employed.1<\/sup> \r\n\r\nAs cor triatriatum remains a rare anomaly, there are limited large studies assessing surgical outcomes. The largest one to date is a descriptive retrospective review of 65 patients treated from 1963-2010 at Boston Children\u2019s Hospital. The median age at surgical repair was 6.9 months with a range from 2 days to 47 years. Over half of the patients were infants. Additional cardiac anomalies were found in 75% of the patients, with atrial septal defect, ventricular septal defect, and partial anomalous pulmonary venous return being the most common. The two deaths that occurred in the early postoperative period were in infants operated on in the 1970\u2019s. In the remaining patients, there was no recurrence of obstruction in the atrium. However, approximately 10% developed pulmonary vein stenosis that required interventional or surgical management.2<\/sup> \r\n\r\nA more recent retrospective review describes 16 patients treated from 2000-2020 at the University of Minnesota. The median age at diagnosis was 4.3 months with a range from 1 day to 7 years. Additional cardiac anomalies were found in 81% of the patients. The CTS created a clinically significant obstruction in 50% of patients. Twelve patients underwent surgical repair. Two patients had early postoperative surgical mortality. These patients had additional congenital cardiac anomalies, one with heterotaxy and complex single ventricle anatomy and one with total anomalous pulmonary venous return. The remaining 10 surgical patients did well with no recurrence of obstruction in the atrium on follow-up.3<\/sup> \r\n\r\nThe image in the scenario clearly shows a left atrial membrane, effectively separating it in proximal and distal portions. Cor triatriatum dexter would result from a right atrium membrane, and no membrane would be seen in context of pure mitral stenosis. \r\n\r\n \r\nREFERENCES \r\n\r\n1.\tKumar Jha A, Makhija N. Cor Triatriatum: a review. Semin Cardiothorac Vasc Anesth<\/em>. 2017 Jun;21(2):178-85. \r\n2.\tKazanci SY, Emani S, McElhinney DB. Outcome after repair of cor triatriatum. Am J Cardiol<\/em>. 2012 Feb 1;109(3):412-6. \r\n3.\tMashadi AH, Narasimhan SL, Said SM. Cor triatriatum sinister: long-term surgical outcomes in children and a proposal for a new classification.J Card Surg<\/em>. 2022 Dec;37(12):4526-33.\r\n”,”hint”:””,”answers”:{“bkkc4”:{“id”:”bkkc4″,”image”:””,”imageId”:””,”title”:”A.\tCor triatriatum dexter “},”uovkd”:{“id”:”uovkd”,”image”:””,”imageId”:””,”title”:”B.\tCor triatriatum sinister”,”isCorrect”:”1″},”zvgdv”:{“id”:”zvgdv”,”image”:””,”imageId”:””,”title”:”C.\tMitral stenosis “}}}}}}

{“questions”:{“jj06y”:{“id”:”jj06y”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Anila B. Elliott, MD – University of Michigan, C.S. Mott Children\u2019s Hospital \r\n\r\nA 5-day-old male with d-Transposition of the Great Arteries (TGA) and ventricular septal defect presents for arterial switch operation. Which one of the following perioperative factors would INCREASE the risk of poor neurodevelopmental outcomes in this patient? “,”desc”:”EXPLANATION \r\nOver the last few decades, survival for those with congenital heart disease (CHD) has improved as advancements in management have led to innovative treatment for even those with more complex anatomy. However, despite a survival improvement, neurodevelopmental outcomes have not improved in the same manner. Children with CHD are at increased risk for a variety of neurodevelopmental issues including motor delays, impaired language development, and reduced cognitive performance. Some of these deficits are more pronounced in those with more complex congenital heart disease, such as a lower intelligence quotient (IQ) in those with hypoplastic left heart syndrome (HLHS) compared to those with atrial septal defects (ASD)^{1<\/sup>.\r\n\r\nIn the latest American Heart Association (AHA) guidelines, new research has led to improved understanding regarding perioperative risk factors that impact neurodevelopment1<\/sup>. Genetic predisposition, perinatal, socioeconomic, and perioperative factors all play a role in long-term neurodevelopmental outcomes 1,2<\/sup>. \r\n\r\nA summary of major risk factors for neurodevelopmental impairment can be found below:1,2<\/sup>: \r\n1.\tGenetic predisposition \r\na.\tSyndromes (Down syndrome, 22q11.2 deletions, William syndrome, Turner syndrome)\r\nb.\tMale gender\r\nc.\tExtracardiac anomalies\r\n2.\tFetal and perinatal factors \r\na.\tCyanosis with hypoxia and reduced nutrient delivery \r\nb.\tPrematurity, especially in those with transposition of great arteries (TGA) or single-ventricle physiology\r\nc.\tPost-natal diagnosis of CHD requiring early surgical intervention\r\n3.\tSurgical and perioperative factors \r\na.\tPerioperative seizures in infancy\r\nb.\tBrain injury (white matter injury, stroke) \r\nc.\tIncreased post-operative length of stay (>14 days) \r\nd.\tCardiopulmonary resuscitation or cardiac arrest \r\ne.\tMechanical circulatory support\r\nf.\tHeart transplantation in childhood \r\ng.\tNeed for multiple interventions or complications \r\n4.\tPsychosocial factors \r\na.\tLow socioeconomic status \r\nb.\tLow maternal education \r\nc.\tSignificant parental mental health challenges (anxiety, depression, post-traumatic stress disorder [PTSD]) \r\n5.\tGrowth and developmental factors \r\na.\tFeeding difficulties \r\nb.\tGrowth failure (including low birth weight and failure to thrive) \r\nc.\tHistory of developmental delay \r\n6.\tOther factors \r\na.\tAbnormal fetal cerebral blood flow \r\nb.\tAbnormal placental development \r\nc.\tExposure to environmental neurotoxins \r\n \r\nPerioperative seizures (Answer A) are strongly associated with poor neurodevelopmental outcomes. Seizures are linked to underlying brain injury and predict long-term deficits in cognitive, academic, and functional abilities1,2<\/sup>. \r\n\r\nDelays in surgical correction are also associated with poorer neurodevelopmental outcomes. For example, in neonates with TGA, prolonged time to arterial switch surgery has been shown to increase the risk of white matter ischemia, which is tied to subsequent neurodevelopmental impairments3<\/sup>. This concern is consistent with earlier findings that delayed surgical intervention is linked to impaired brain growth and worse language development2<\/sup>. \r\n\r\nWhile lower hematocrit levels and hypotension during CPB may impair oxygen delivery, and theoretically contribute to cerebral hypoperfusion and injury, the direct long-term impact of this on neurodevelopment has not been well-established. There is no current data to support specific thresholds for mean arterial pressure (MAP) or hematocrit during bypass that is predictive of preventing poor neurodevelopmental outcomes across large populations1,2,4<\/sup>. \r\n\r\nThe correct answer is A, perioperative seizures increase the likelihood of poor neurodevelopmental outcomes based on the most recent AHA guidelines1<\/sup>. Although lower hematocrit and hypotension may play a role, there is no definitive data to recommend specific surgical, hemodynamic, or transfusion practices in the congenital cardiac patient population to prevent neurodevelopmental impairment. \r\n\r\n \r\nREFERNCES \r\n1.\tSood E, Newburger JW, Anixt JS, et al. Neurodevelopmental Outcomes for Individuals With Congenital Heart Disease: Updates in Neuroprotection, Risk-Stratification, Evaluation, and Management: A Scientific Statement From the American Heart Association. Circulation<\/em>. 2024;149(13):e997-e1022. doi:10.1161\/CIR.0000000000001211 \r\n2.\tWernovsky G, Licht DJ. Neurodevelopmental Outcomes in Children With Congenital Heart Disease-What Can We Impact?. Pediatr Crit Care Med<\/em>. 2016;17(8 Suppl 1):S232-S242. doi:10.1097\/PCC.0000000000000800 \r\n3.\tLim JM, Porayette P, Marini D, et al. Associations Between Age at Arterial Switch Operation, Brain Growth, and Development in Infants With Transposition of the Great Arteries. Circulation<\/em>. 2019;139(24):2728-2738. doi:10.1161\/CIRCULATIONAHA.118.037495 \r\n4.\tGaynor JW, Stopp C, Wypij D, et al. Neurodevelopmental outcomes after cardiac surgery in infancy. Pediatrics<\/em>. 2015;135(5):816-825. doi:10.1542\/peds.2014-3825\r\n\r\n”,”hint”:””,”answers”:{“71s2z”:{“id”:”71s2z”,”image”:””,”imageId”:””,”title”:”A.\tPerioperative seizures”,”isCorrect”:”1″},”2w3gg”:{“id”:”2w3gg”,”image”:””,”imageId”:””,”title”:”B.\tMean arterial pressure (MAP) < 50mmHg on cardiopulmonary bypass (CPB)"},"trorh":{"id":"trorh","image":"","imageId":"","title":"C.\tHematocrit < 35% during cardiopulmonary bypass (CPB)\r\n\r\n"}}}}}}

{“questions”:{“fthbd”:{“id”:”fthbd”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Jeremy Friedman, MD, Robert Wong, MD, Michael Goulet, MD – Cedars-Sinai Medical Center \r\n\r\nA 16-year-old male with a history of Tetralogy of Fallot repair with a transannular patch as an infant presents for transcatheter pulmonary valve replacement (TPVR). He has severe pulmonary valve regurgitation with a right ventricular end diastolic volume index of (RVEDVI) of 180 ml\/m2, and worsening exercise tolerance. After deployment of the transcatheter pulmonary valve, regional wall motion abnormalities are immediately noted on transesophageal echocardiogram. Which of the following is the most likely cause?”,”desc”:”EXPLANATION \r\nPulmonary valve regurgitation is expected after a Tetralogy of Fallot (TOF) repair with a transannular patch. Long-standing pulmonary valve regurgitation can cause right ventricular (RV) volume overload and dilation. These changes can lead to RV systolic and diastolic dysfunction, RV remodeling, arrhythmias, and exercise intolerance. Pulmonary valve replacement (surgical or percutaneous) is recommended for relief of symptoms in patients with repaired TOF and moderate or greater pulmonary regurgitation (PR) with cardiovascular symptoms not otherwise explained. \r\nThe following are the AHA\/ACC criteria for pulmonary valve replacement (PVR) in patients with a TOF repair with PR^{1<\/sup>: \r\n\r\nModerate or severe PR (typically defined as regurgitant fraction >25%) PLUS any two of the following: \r\n\r\n1. Cardiovascular symptoms that are not otherwise explained \r\n2. Mild or moderate RV or LV dysfunction \r\n3. Severe RV dilation: RVEDVI of \u2265160 mL\/m2<\/sup>, OR right ventricular end systolic volume index (RVESVI) \u2265 80 mL\/m2<\/sup>, OR right ventricular end diastolic volume (RVEDV) \u2265 2x left ventricular end diastolic volume (LVEDV) \r\n4. Right ventricular systolic pressure (RVSP) \u2265 2\/3 systemic pressure \r\n5. Progressive reduction in objective exercise tolerance \r\n\r\nCardiac MRI is a useful tool to quantify RV size and function, pulmonary valve function, pulmonary artery anatomy, and any left heart abnormalities, while cardiac CT is required to evaluate suitable RVOT anatomy for a transcatheter pulmonary valve. \r\n\r\nCoronary artery (CA) compression is a well-known complication of TPVR. Congenital and postoperative abnormalities in CA anatomy are seen not only in TOF patients, but also in other patients with conotruncal abnormalities. Even with normal CA anatomy, rotation or anterior displacement of the aorta, surgical reimplantation of CAs, or a dilated pulmonary artery can place the patient at risk for CA compression depending on the relative location of the RVOT. \r\nCoronary artery compression is a life-threatening complication. Because of this possibility, it is crucial for the interventionalist to perform coronary angiography with a simultaneous balloon test of the RVOT prior to pulmonary valve deployment2<\/sup>. This maneuver allows the interventionalist to see, prior to valve deployment, if the transcatheter valve will compress any of the coronary arteries leading to myocardial ischemia and wall motion abnormalities on echocardiography. \r\n\r\nA multi-center study by Morray et al looked at 404 patients (median age 18 years) who underwent cardiac catheterization for potential TPVR. CA compression occurred in 5% of patients during test balloon angiography. Patients with TOF and TGA were at highest risk for CA compression. Following successful test balloon angiography and subsequent TPVR, no patient developed clinically significant CA compression2<\/sup>. \r\n\r\nOther complications of TPVR include native pulmonary artery or RVOT conduit rupture and ventricular arrhythmias3,4<\/sup>. Risk factors for rupture include heavy calcifications of the conduit or RVOT homograft valve. A contained rupture may be controlled with a covered stent, but a noncontained rupture may be a surgical emergency. Intraoperative or postoperative ventricular arrhythmias may occur due to the interaction between the device and the native RVOT tissue. \r\n\r\nIn the scenario described above, the correct answer is C) coronary artery compression. Regional wall motion abnormalities are most likely caused by coronary artery compression from the new transcatheter pulmonary valve. There is no note of a PA rupture on imaging or acute right ventricular failure which would lead to global ventricular dysfunction on transesophageal echocardiogram. \r\n\r\n \r\nREFERENCES \r\n1.\tStout, KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA\/ACC guideline for the management of adults with congenital heart disease: A report of the American College of Cardiology\/American Heart Association Task Force on Clinical Practice Guidelines. Circulation<\/em>. 2019; 139:e698-e800. \r\n2.\tMorray, BH, McElhinney DB, Cheatham JP et al. Risk of coronary artery compression among patients referred for transcatheter pulmonary valve implantation. Circulation: Cardiovascular Interventions<\/em>. 2013; 6:535-542. \r\n3.\tMueller AS, McDonald DM, Singh HS, Ginns JN. Heart failure in adult congenital heart disease: Tetralogy of Fallot. Heart Failure Reviews<\/em>. 2020; 25:583-598. \t\t\r\n4.\tBoudjemline Y, Malekzadeh-Milani S, Patel M et al. \u201cPredictors and outcomes of right ventricular outflow tract conduit rupture during percutaneous pulmonary valve implantation: A multicentre study.\u201d EuroIntervention<\/em>. 2016; 11:1053-1062.\r\n”,”hint”:””,”answers”:{“r8zkv”:{“id”:”r8zkv”,”image”:””,”imageId”:””,”title”:”A. Acute right ventricular failure “},”c8m16”:{“id”:”c8m16″,”image”:””,”imageId”:””,”title”:”B. Pulmonary artery rupture”},”tbogb”:{“id”:”tbogb”,”image”:””,”imageId”:””,”title”:”C. Coronary artery compression”,”isCorrect”:”1″}}}}}}

{“questions”:{“fuz4p”:{“id”:”fuz4p”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:”https:\/\/ccasociety.org\/wp-content\/uploads\/2025\/09\/CCAS-QOW-9-11-25-Pic.png”,”imageId”:”9064″,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Anila B Elliott, MD – University of Michigan, C.S. Mott Children\u2019s Hospital \r\n\r\nA 10-year-old with bicuspid aortic valve presents for a Ross procedure. They are consented for a deep parasternal intercostal plane (DPIP) block. What is the correct order of anatomical structures in the ultrasound image below, from superficial to deep (1 to 6)?”,”desc”:”EXPLANATION \r\nThe deep parasternal intercostal plane (DPIP) block is a regional technique used to provide analgesia to the anterior chest wall. This block targets the anterior branches of the intercostal nerves (T2-T6) as they course anterior to the internal mammary vasculature. Local anesthetic is deposited into the fascial layer between the internal intercostal muscle and the transversus thoracic muscle^{1,2<\/sup>. As local anesthetic is injected, these layers are separated, as illustrated in Figure 1.\r\n\r\nFigure 1: Image A: The needle is seen traversing the tissue layers prior to injection of local anesthetic. Note the location of the pleura (arrow). Image B: Following injection, the anesthetic spreads and separates the tissue layers, displacing the pleura inferiorly. \r\n \r\n \r\n\r\nUtilization of the DPIP block has been shown to decrease post-operative pain scores and reduce opioid requirements following pediatric cardiac surgery3<\/sup>. Cadaveric studies have shown that the local anesthetic spread of the DPIP block covers a broader area than the superficial parasternal muscle plane (SPIP) block, offering enhanced pain control4<\/sup>. However, the DPIP is considered a more advanced block as it carries a potential risk of vascular injury, as the needle tip may come within millimeters of the internal mammary artery 4,5<\/sup>. \r\n\r\nOther regional blocks of the anterior chest wall include the PECS I and PECS II blocks. The PECS I block traverses the pectoralis major and deposits local anesthetic between the pectoralis major and pectoralis minor, targeting the pectoral nerves. The PECS II block traverses the pectoralis major and pectoralis minor muscles to deposit local anesthetic between the pectoralis minor and the serratus anterior muscle, targeting the lateral cutaneous intercostal nerves (T2-T6)6<\/sup>. \r\n\r\nThe correct answer is A \u2013 the layers depicted in the picture from superficial to deep are the pectoralis major, external intercostal muscle, internal intercostal muscle, transversus thoracic muscle, internal mammary artery, and the pleura.\r\n\r\n \r\nREFERENCES \r\n1.\tCakmak M, Isik O. Transversus Thoracic Muscle Plane Block for Analgesia After Pediatric Cardiac Surgery. J Cardiothorac Vasc Anesth<\/em>. 2021;35(1):130-136. doi:10.1053\/j.jvca.2020.07.053 \r\n2.\tAydin ME, Ahiskalioglu A, Ates I, et al. Efficacy of Ultrasound-Guided Transversus Thoracic Muscle Plane Block on Postoperative Opioid Consumption After Cardiac Surgery: A Prospective, Randomized, Double-Blind Study. J Cardiothorac Vasc Anesth<\/em>. 2020;34(11):2996-3003. doi:10.1053\/j.jvca.2020.06.044 \r\n3.\tCui YY, Xu ZQ, Hou HJ, Zhang J, Xue JJ. Transversus Thoracic Muscle Plane Block For Postoperative Pain in Pediatric Cardiac Surgery: A Systematic Review And Meta-Analysis of Randomized And Observational Studies. J Cardiothorac Vasc Anesth<\/em>. 2024;38(5):1228-1238. doi:10.1053\/j.jvca.2024.02.016 \r\n4.\tDouglas RN, Kattil P, Lachman N, et al. Superficial versus deep parasternal intercostal plane blocks: cadaveric evaluation of injectate spread. Br J Anaesth<\/em>. 2024;132(5):1153-1159. doi:10.1016\/j.bja.2023.08.014 \r\n5.\tSepolvere G, Togn\u00f9 A, Tedesco M, Coppolino F, Cristiano L. Avoiding the Internal Mammary Artery During Parasternal Blocks: Ultrasound Identification and Technique Considerations. J Cardiothorac Vasc Anesth<\/em>. 2021;35(6):1594-1602. doi:10.1053\/j.jvca.2020.11.007 \r\n6.\tDost B, De Cassai A, Amaral S, et al. Regional anesthesia for pediatric cardiac surgery: a review. BMC Anesthesiol<\/em>. 2025;25(1):77. Published 2025 Feb 15. doi:10.1186\/s12871-025-02960-z \r\n”,”hint”:””,”answers”:{“5zpwr”:{“id”:”5zpwr”,”image”:””,”imageId”:””,”title”:”A.\tPectoralis major — external intercostal — internal intercostal — transversus thoracic muscle — internal mammary artery — pleura\r\n”,”isCorrect”:”1″},”wpy46″:{“id”:”wpy46″,”image”:””,”imageId”:””,”title”:”B.\tPectoralis major — pectoralis minor — intercostal — transversus thoracic muscle — internal mammary artery — pleura”},”x7jb3″:{“id”:”x7jb3″,”image”:””,”imageId”:””,”title”:”C.\tPectoralis major — serratus anterior — intercostal –transversus thoracic muscle — internal mammary artery — pleura\r\n\r\n”}}}}}}

{“questions”:{“2p83i”:{“id”:”2p83i”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Kanwarpal Singh Bakshi, MD – Children\u2019s Hospital Los Angeles \r\nA 3\u202fkg neonate undergoes a Norwood-mBTT shunt procedure for hypoplastic left heart syndrome (HLHS). Following a prolonged cardiopulmonary bypass run, the patient is placed on veno-arterial (VA) ECMO postoperatively. After several days of support, a clamp trial is performed to assess readiness for decannulation. The patient is transitioned to full mechanical ventilation and restarted on inotropic support. The patient immediately demonstrates signs of hemodynamic instability and inadequate gas exchange, and the trial is aborted. Upon reinstitution of VA ECMO with adequate circuit flow, the patient exhibits persistently low saturations. The ECMO circuit appears intact with no signs of clot or flow disturbance. Which of the following is the MOST LIKELY cause of the desaturation?\r\n”,”desc”:”EXPLANATION \r\nExtracorporeal membrane oxygenation (ECMO) is a form of temporary mechanical support for patients with severe, life-threatening cardiac or respiratory failure. In neonates and infants with congenital heart disease, particularly following complex surgical interventions such as the Norwood procedure for hypoplastic left heart syndrome (HLHS), ECMO provides a vital bridge to recovery or further surgical intervention.^{\u00b9<\/sup> In veno-arterial (VA) ECMO, deoxygenated blood is drained from the venous system\u2014typically via the right atrium or internal jugular vein\u2014and pumped through a membrane oxygenator where gas exchange occurs. The oxygenated blood is then returned to the arterial system, usually via the aorta or carotid artery, to support systemic circulation and oxygen delivery.\u00b2,\u00b3<\/sup> \r\nVA ECMO differs from veno-venous (VV) ECMO in that it supports both the heart and lungs. This makes it the preferred mode in patients with significant myocardial dysfunction, such as those who have undergone a Norwood procedure. Typical VA ECMO parameters include flow rates of 100\u2013150 mL\/kg\/min, careful monitoring of circuit pressures, and regular assessment of gas exchange and end-organ perfusion.\u00b9,\u00b3<\/sup> \r\nKey circuit components include a centrifugal pump, a membrane oxygenator, a sweep gas system, and a heat exchanger. The sweep gas, typically 100% oxygen or a blended gas, drives the removal of carbon dioxide and supports oxygenation across the membrane. Without active sweep flow, the membrane oxygenator cannot perform gas exchange, rendering the circuit ineffective for oxygen delivery. \r\nWhen there is evidence of cardiac and pulmonary recovery, clinicians may attempt aclamp trial<\/em>.\u2074<\/sup> Prior to clamping off, the ECMO flows are gradually weaned and the patient is transitioned to full ventilator and inotropic support. Echocardiography is performed during weaning to assess myocardial recovery, assessing LV\/RV contractility, ventricular unloading, atrioventricular valve competency, and neo\/aortic valve opening. If everything looks favorable, the clamp trial begins as ECMO flow is stopped by clamping both the venous and arterial cannulae. \r\nIt is standard practice to discontinue the sweep gas to the oxygenator during the clamp trial.\u2074<\/sup> Although ECMO flow to the patient is halted, residual blood remains in the ECMO circuit, and low-flow recirculation through a bridge between the venous and arterial limbs is typically maintained to prevent blood stasis and reduce the risk of thrombosis. Leaving the sweep gas on allows continued gas exchange in the oxygenator, which can strip CO_{\u2082<\/sub> from the blood. As a result, the blood in the circuit becomes progressively hypocarbic. When the trial ends and full ECMO support is reinitiated, this hypocarbic blood is reinfused into the patient, potentially leading to abrupt systemic hypocarbia. Such sudden changes in PaCO\u2082<\/sub> can cause cerebral vasoconstriction, reducing cerebral blood flow and increasing the risk of neurologic complications, especially in neonates who have immature autoregulatory mechanisms. To avoid this, the sweep gas will be turned off during a clamp trial to prevent alterations in blood gas composition within the idle circuit. \r\nIf the patient fails to tolerate the clamp trial, as demonstrated by persistently low mixed venous oxygen saturations, rising lactate, worsening acidosis, or hypotension, ECMO must be urgently reinitiated.\u00b2,\u2074<\/sup> As part of this reinitiation, it is essential to ensure that sweep gas is turned back on and adjusted appropriately. Failure to do so can result in continued inadequate oxygenation and CO\u2082<\/sub> clearance, further worsening the patient\u2019s condition. Additionally, ventilator and inotropic support must be carefully titrated before, during, and after the trial to optimize conditions for both native and mechanical support.\u2074<\/sup> \r\nIn neonates with single-ventricle physiology, particularly after the Norwood procedure, clamp trials can fail for several reasons. These patients rely on a delicate balance between systemic and pulmonary blood flow (Qp:Qs), and myocardial recovery may be incomplete following a prolonged cardiopulmonary bypass run. Additionally, pulmonary vascular resistance may still be elevated, or the lungs may have residual injury or edema.\u00b3<\/sup> Even with restored ventilation and inotropes, the circulation may not be capable of supporting end-organ perfusion without extracorporeal assistance. Finally, given the technical nature of the Norwood procedure, the patient may need to return to surgery to revise the shunt or Damus\u2013Kaye\u2013Stansel (DKS) anastomosis. \r\nAn alternative to the traditional clamp-off trial is the pump-controlled retrograde trial off <\/em>(PCRTO) protocol, which allows for a more gradual assessment of the patient’s readiness for decannulation.\u2075<\/sup> In this method, the centrifugal pump speed is reduced to allow retrograde flow through the arterial cannula. This setup minimizes ECMO support while preserving circuit patency, enabling continued low-flow circulation and reducing the risk of thrombus formation. Unlike the abrupt cessation seen in clamp trials, PCRTO enables a more physiologic transition to native circulation, mitigating hemodynamic instability.\u2075<\/sup> This method is especially valuable in neonates and critically ill patients with marginal myocardial recovery, as it provides a safety mechanism for immediate reinitiation of full support if the patient fails the trial. Additionally, it allows for longer evaluation periods than clamp-off trials, facilitating a more accurate assessment of cardiopulmonary readiness for decannulation.\u2075<\/sup> \r\nOther answer choices are less consistent with the clinical presentation. Air entrainment (A) into the arterial cannula would result in immediate hemodynamic collapse or neurologic injury due to arterial embolism. Oxygenator failure (C) usually presents gradually, with rising transmembrane pressure gradients, worsening oxygenation over hours, and sometimes hemolysis\u2014not an abrupt desaturation event after reinitiating ECMO. \r\n \r\nREFERENCES \r\n1. Valencia E, Nasr VG. Updates in Pediatric Extracorporeal Membrane Oxygenation. J Cardiothorac Vasc Anesth<\/em>. 2020;34(5):1309\u20131323. doi:10.1053\/j.jvca.2019.09.006. \r\n2. Peek GJ, Harvey C. Weaning and decannulation in neonatal respiratory failure. In: MacLaren G, Brodie D, Lorusso R, Peek G, Thiagarajan R, Vercaemst L. Extracorporeal Life Support: The ELSO Red Book. 6th ed. Extracorporeal Life Support Organization; 157-164. \r\n3. Nadkarni AS, Delany DR, Schramm J, Shin YR, Hoskote A, Bembea MM. ECMO considerations in the pediatric cardiac population. Curr Pediatr Rep<\/em>. 2023;11(2):86\u201395. doi:10.1007\/s40124-023-00292-5. E McCartney SL, Krishnan S. \r\n4. Krishnan S, Schmidt GA. ECMO Weaning and Decannulation. In: Schmidt GA, ed. Extracorporeal Membrane Oxygenation for Adults. 3rd ed. Springer; 2022:265\u2013275. \r\n5. Stukov Y, Dibert TT, Narasimhulu SS, et al. Pump-controlled retrograde trial off extracorporeal membrane oxygenation. Multimedia Manual of Cardiothoracic Surgery<\/em>. 2025. Available from: https:\/\/mmcts.org\/tutorial\/1972\r\n\r\n”,”hint”:””,”answers”:{“m3uu4”:{“id”:”m3uu4″,”image”:””,”imageId”:””,”title”:”A. Air entrainment in the arterial cannula”},”b9nnj”:{“id”:”b9nnj”,”image”:””,”imageId”:””,”title”:”B. Sweep gas flow was not restored”,”isCorrect”:”1″},”bim84″:{“id”:”bim84″,”image”:””,”imageId”:””,”title”:”C. Oxygenator membrane failure”}}}}}}}