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

{“questions”:{“6u76f”:{“id”:”6u76f”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Nicholas Houska, DO – University of Colorado, Children\u2019s Hospital Colorado \r\nA five-month-old boy has just undergone repair of a perimembranous ventricular septal defect utilizing cardiopulmonary bypass. Shortly after aortic cross clamp removal, the ECG exhibits ST segment elevation in leads II, III, and AVF. Administration of which of the following drugs is the MOST appropriate treatment?”,”desc”:”EXPLANATION \r\nCongenital cardiac surgery often poses the risk for air to enter the left sided cardiac structures, which can subsequently be embolized to the systemic circulation. Due to its anterior location, the right coronary artery is a common anatomical site for air to travel after release of the aortic cross clamp. This typically presents as ST segment elevation on the ECG and a variable degree of right ventricular dysfunction or arrythmias. Given the spectrum of congenital cardiac lesions, air embolism to the left coronary artery should also be considered in situations where it is anatomically located in a non-dependent area, and if clinical signs are suggestive. Management of coronary air embolism involves increasing the coronary perfusion pressure by increasing the aortic diastolic blood pressure. This often requires co-management between the anesthesiologist, surgeon, and perfusionist to decide the best method to increase diastolic blood pressure. Often a combination of increasing cardiopulmonary bypass flow and administration of vasoactive medications is usually successful. Myocardial dysfunction and ECG changes are typically transient, though this may be a cause of difficulty in separating from cardiopulmonary bypass due to arrythmia or ventricular dysfunction. \r\n\r\nThe correct answer in the scenario is A, administration of phenylephrine to increase the coronary perfusion pressure. Other treatments include increasing the cardiopulmonary bypass pump flow or administration of other vasoactive agents, such as norepinephrine, epinephrine or vasopressin. These treatment options typically provide sufficient pressure to force the air bubbles through the coronary circulation. Administration of nitroglycerin is unlikely to be of benefit as the problem is related to a mechanical obstruction with air rather than coronary vasospasm. Esmolol is not the best option in this clinical scenario, though prevention of tachycardia is helpful to decrease myocardial oxygen demand. \r\n\r\n \r\nREFERENCES \r\nMonaco F, Di Prima AL, Kim JH et al. Management of Challenging Cardiopulmonary Bypass Separation. J Cardiothorac Vasc Anesth<\/em>. 2020;34(6):1622-1635. doi: 10.1053\/j.jvca.2020.02.038. \r\n\r\nSarkar M, Prabhu V. Basics of cardiopulmonary bypass. Indian J Anaesth<\/em>. 2017;61(9):760-767. doi: 10.4103\/ija.IJA_379_17.\r\n”,”hint”:””,”answers”:{“4s6r1”:{“id”:”4s6r1″,”image”:””,”imageId”:””,”title”:”A. Phenylephrine “,”isCorrect”:”1″},”lfmru”:{“id”:”lfmru”,”image”:””,”imageId”:””,”title”:”B. Esmolol”},”kx80v”:{“id”:”kx80v”,”image”:””,”imageId”:””,”title”:”C. Nitroglycerin \r\n\r\n”}}}}}

{“questions”:{“6tspy”:{“id”:”6tspy”,”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 one-month-old infant born to Hispanic parents in Southern Colorado presents with facial abnormalities, seizure disorder, congenital heart disease, and developmental delay. He is diagnosed with recombinant chromosome 8 syndrome (San Luis Valley Syndrome). Which of the following congenital heart defects is MOST likely to be associated with this syndrome?”,”desc”:”EXPLANATION \r\nFirst described by Fujimoto in 1975, Recombinant 8 syndrome, also known as San Luis Valley syndrome, is a rare genetic disorder most frequently encountered in children of Hispanic descent in the southwestern United States. This syndrome is presumed to have originated from a single founder who emigrated from Spain to Colorado or New Mexico. There is a 6.2 % risk for a parental carrier of the gene to have a child with the phenotype, with males and female offspring equally affected. The hallmarks of the disease are dysmorphic features, congenital heart defects, and developmental delay. Diagnosis is made through chromosomal analysis in children with clinical features and parental risk factors. Genetic counseling for families is recommended due to the carrier rate.\r\n\r\nThe dysmorphic features of children with San Luis Valley syndrome most commonly feature hypertelorism, wide face, thin upper lip, anteverted nares, abnormal hair whorl and infraorbital creases. These children also present with musculoskeletal abnormalities including abnormal tone, clinodactyly, deep plantar furrows, scoliosis, and pectus excavatum. Urogenital abnormalities are also common. Congenital heart disease is found in nearly all children with San Luis Valley syndrome, most commonly atrial septal defects and ventricular septal defects (50-69%), pulmonary stenosis (25-29%), Tetralogy of Fallot (16-40.5%), persistent left superior vena cava (14%) and double outlet right ventricle (8%). Case series have differed on whether these children have adverse surgical outcomes as compared to the general pediatric population, with recent studies (Pickler et al) suggesting no difference. Management includes cardiac, orthopedic, and urological surgery, along with neurodevelopmental support and rehabilitation. The most common cause of death in these children is related to congenital heart disease. \r\n\r\nSan Luis Valley Syndrome is associated with atrial septal and ventricular septal defects, and conotruncal defects such as Tetralogy of Fallot. It is not known to be associated with coarctation of the aorta or hypoplastic left heart syndrome. \r\n\r\n \r\nREFERENCES \r\nGelb BD, Towbin JA, McCabe ER, Sujansky E. San Luis Valley recombinant chromosome 8 and tetralogy of Fallot: a review of chromosome 8 anomalies and congenital heart disease. Am J Med Genet<\/em>. 1991; 40(4): 471-476. doi: 10.1002\/ajmg.1320400420. \r\n\r\nPickler L, Wilson R, Tsai AC. Revisiting recombinant 8 syndrome. Am J Med Genet A<\/em>. 2011; 155A(8): 1923-1929. doi: 10.1002\/ajmg.a.34104. \r\n\r\nHabhab W, Mau-Holzmann U, Singer S, Rie\u00df A, Kagan KO, Gerbig I, Sch\u00e4ferhoff K, Dufke A, Kehrer M. Pre- and postnatal findings in a patient with a recombinant chromosome rec(8)(qter\u2192q21.11:p23.3\u2192qter) due to a paternal pericentric inversion inv(8)(p23.3q21.11) and review of the literature. Am J Med Genet A<\/em>. 2020; 182(11): 2680-2684. doi: 10.1002\/ajmg.a.61804. .\r\n\r\nFujimoto A, Wilson MG, Towner JW. Familial inversion of chromosome No. 8: an affected child and a carrier fetus. Humangenetik<\/em>. 1975; 27(1): 67-73.\r\n\r\n”,”hint”:””,”answers”:{“ewip3”:{“id”:”ewip3″,”image”:””,”imageId”:””,”title”:”A. Tetralogy of Fallot”,”isCorrect”:”1″},”nj0e1″:{“id”:”nj0e1″,”image”:””,”imageId”:””,”title”:”B. Coarctation of the Aorta”},”0rku7″:{“id”:”0rku7″,”image”:””,”imageId”:””,”title”:”C. Hypoplastic Left Heart Syndrome”}}}}}

{“questions”:{“mup28”:{“id”:”mup28″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Melissa Colizza, MD – Stollery Children\u2019s Hospital, Edmonton Canada \r\n\r\nA 3-week-old girl presents with acute onset of shortness of breath and diaphoresis during feeds. A transthoracic echocardiogram demonstrates severe left ventricular dysfunction, moderate mitral regurgitation, and poor visualization of the left coronary ostium. Which of the following diagnoses is the MOST likely cause of severe left ventricular dysfunction?”,”desc”:”EXPLANATION \r\nAn anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare lesion, with an incidence of 1 per 300,000 births. It is also known as Bland-White-Garland syndrome, named after the first clinical description in 1933. Normally, left ventricular (LV) perfusion occurs during ventricular diastole as ventricular systole limits coronary blood flow. In patients with ALCAPA, left ventricular perfusion occurs with mixed venous blood originating from the pulmonary artery due to elevated pulmonary vascular resistance (PVR) over the first weeks of life. However, once PVR and pulmonary artery (PA) pressure begin to decrease over the first several weeks of life, myocardial perfusion also decreases as coronary perfusion pressure and coronary blood flow decrease. This may lead to a reversal in blood flow in the ALCAPA, leading to a \u201ccoronary steal phenomenon\u201d and further increasing the risk of LV ischemia and dysfunction. The right ventricle (RV) remains somewhat protected from ischemia as myocardial perfusion occurs in both systole and diastole. Progression of LV dysfunction will eventually lead to LV dilation and impaired RV filling from interventricular septal shift. Mitral valve regurgitation may also ensue, secondary to annular dilation or papillary muscle ischemia. Mitral regurgitation increases volume load to the LV, thus exacerbating dysfunction and pulmonary congestion. Like other dilated or ischemic cardiomyopathies, patients with ALCAPA are at high risk for ventricular arrhythmias. \r\n\r\nThe presentation of ALCAPA will vary amongst individuals in terms of symptoms and timing. This is mostly due to variations in coronary artery anatomy. A dominant right coronary artery (RCA) will supply a greater proportion of myocardial blood flow and is more likely to result in a later onset of symptoms with less ventricular dysfunction. Stenosis of the ALCAPA might also be beneficial as it reduces coronary steal and favors collateralization from the RCA to the LCA territory, which may minimize myocardial ischemia. A study by Straka et al compared the presentation and outcome of patients with ALCAPA diagnosed in infancy to those diagnosed later in childhood. Most patients who presented in infancy were between two to six months of age, and 62.5% had heart failure as the primary symptom. As expected, most patients had LV dysfunction, LV dilation, and moderate or severe mitral regurgitation. Patients who presented later were more likely to be asymptomatic (62.2%) or have chest pain (20.8%) with preserved LV function. One patient in that group presented with cardiac arrest.\r\n\r\nTreatment consists of re-establishing aortic perfusion to the ALCAPA. It is usually done by reimplantation of the coronary artery to the aorta. The Takeuchi procedure, an alternative surgical technique which can be used in the setting of a short ALCAPA segment, creates an aorto-pulmonary window and an intra-pulmonary baffle from the aorta to the ALCAPA. The study by Stratka and colleagues demonstrated that the early group had surgery between one and three days after diagnosis and that 31.1% required mitral valve repair for more than moderate regurgitation. \r\n\r\nAnesthetic considerations in the pre-bypass phase include maintaining systemic blood flow in the face of potentially severe LV dysfunction and adequate coronary perfusion pressure to the ALCAPA, while avoiding excessive tachycardia to minimize myocardial oxygen consumption. Induction is high risk and should be done in a slow, titrated manner. These patients are also at high risk for arrhythmias such as ventricular fibrillation due to myocardial ischemia, such that defibrillation or rapid institution of cardiopulmonary bypass may be required. Finally, maintaining a relatively elevated PVR will promote perfusion to the ALCAPA. Therefore, maintaining a moderately elevated PaCO2 and limiting the inspired oxygen concentration will achieve an elevated PVR. After repair, myocardial recovery is not immediate, and patients are likely to require high doses of vasoactive medications or mechanical circulatory support. \r\n\r\nSurgical outcomes are generally excellent but are less favorable in those who present at a younger age. The study by Straka et al demonstrated that only one child in the <1 year of age group died, four (8.9%) required extracorporeal membrane oxygenation, and 29 (64.4%) had delayed sternal closure. However, there was no mortality, no need for mechanical support, and no need for delayed sternal closure in the late onset group. Moreover, hospital length-of-stay was significantly shorter in the late onset group. Interestingly, while the early onset group had more than moderate LV dilation and mitral regurgitation at discharge, these parameters were no longer significant at the one-year follow-up. An additional retrospective analysis of surgical outcomes by El-Louali et al that compared patients with an early onset to a late onset of symptoms demonstrated that early onset patients had a significantly more severe clinical presentation and LV dysfunction, higher incidence of delayed sternal closure, longer duration of mechanical ventilation and longer ICU lengths of stay.\r\n\r\nALCAPA and dilated cardiomyopathy have very similar clinical presentations in the infant population. However, the echocardiographic findings described in the stem are highly suggestive of ALCAPA. Dilated cardiomyopathy is more likely to present with echocardiographic findings of biventricular enlargement and clearly delineated coronary ostia. Kawasaki disease may give rise to coronary anomalies in the form of aneurysms and may lead to myocardial ischemia, but the absence of a viral prodrome and typical rash along with the lack of coronary aneurysms make this diagnosis less likely. \r\n\r\n\r\nREFERENCES \r\n \r\n\r\nMcKenzie I, Zestos MK, Stayer SA, Kaminski E, Davies P, Andropoulos DB. Anesthesia for Miscellaneous Cardiac Lesions. In: Andropoulos DB, Mossad EB, Gottlieb EA, eds. Anesthesia for Congenital Heart Disease<\/em>. Fourth edition. John Wiley & Sons, Inc.; 2023: 795-800.\r\n\r\nStraka N, Gauvreau K, Huang Y, et al. Analysis of Perioperative and Long-Term Outcomes Among Presentations of Anomalous Left Coronary Artery from the Pulmonary Artery Diagnosed Beyond Infancy Versus During Infancy. Pediatr Cardiol<\/em>. Published online December 15, 2023. doi:10.1007\/s00246-023-03344-1\r\n\r\n\r\nEl-Louali F, Lenoir M, Gran C, Allary C, Fouilloux V, Ovaert C. Early Presentation of Patients with Abnormal Origin of Left Coronary Artery from the Pulmonary Artery is a Predictor of Poor Mid-term Outcomes. Pediatr Cardiol<\/em>. 2022;43(4):719-725. doi:10.1007\/s00246-021-02777-w\r\n”,”hint”:””,”answers”:{“ece6u”:{“id”:”ece6u”,”image”:””,”imageId”:””,”title”:”A)\tAnomalous Left Coronary Artery from the Pulmonary Artery”,”isCorrect”:”1″},”v5gs2″:{“id”:”v5gs2″,”image”:””,”imageId”:””,”title”:”B)\tDilated Cardiomyopathy”},”zpak9″:{“id”:”zpak9″,”image”:””,”imageId”:””,”title”:”C)\tKawasaki disease\r\n\r\n”}}}}}

{“questions”:{“qff7c”:{“id”:”qff7c”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Melissa Colizza, MD – Stollery Children\u2019s Hospital, Edmonton Canada \r\n\r\nA 3-day-old boy is diagnosed with pulmonary atresia and an intact ventricular septum. After stabilization with a prostaglandin infusion, which of the following procedures is the MOST appropriate next step in management? “,”desc”:”EXPLANATION \r\n\tPulmonary atresia with intact ventricular septum (PA\/IVS) is a rare right-sided obstructive lesion, with an incidence of 1-3% in the congenital heart disease population. It is characterized by an imperforate pulmonary valve, absence of antegrade blood flow from the right ventricle (RV) to the pulmonary arteries (PA), an intact ventricular septum and a variable degree of RV hypoplasia. Disease severity and management options are determined primarily by the size of the RV and the tricuspid valve annulus. Embryologically, flow across the tricuspid valve into the RV and through the PAs is critical for adequate development of the RV. With an atretic pulmonary valve, RV growth will be limited, and the ventricle will remain small and hypertensive. RV hypertension allows ventricular sinusoids to remain open, and to potentially create ventriculo-coronary fistulas, which are present in 50% of children with PA\/IVS. \r\n\r\n\r\n\tCoronary fistulas can increase the risk of coronary ischemia from RV steal during RV decompression. In the presence of proximal coronary stenosis or atresia, perfusion of the distal myocardium will be dependent on the deoxygenated blood coming retrogradely from the RV sinusoids. This phenomenon is referred to RV-dependent-coronary-circulation (RVDCC). The definition of RVDCC varies somewhat, but it is commonly described as the presence of ventriculo-coronary connections with angiographically severe obstruction of at least two major coronary arteries, complete aorto-coronary atresia, or situations in which a significant portion of the left ventricular myocardium is supplied directly by the RV. Other centers use the presence of any coronary-cameral fistula with proximal obstruction and angiographic evidence of RV myocardial perfusion through those fistulous connections. Spigel et al analyzed the outcomes of 103 patients with PA\/IVS, 28 of whom had RVDCC. RVDCC was further classified based on location of coronary obstruction. Eighteen (64%) of the RVDCC patients had proximal obstruction, and the left anterior descending artery was involved in 23 (82%) patients. Mortality rate was 36%. Transplant-free survival was 54% at 6 months, and 46% at 1 and 10 years. Patients with proximal obstruction had decreased transplant-free survival compared to those with distal obstruction (44% vs 70% at 6 months). The authors inferred that proximal stenosis places a higher mass of myocardium at risk for ischemia. Interestingly, patients with distal obstruction did not have a statistically significant difference in transplant-free survival from patients without RVDCC. In 2023, Cheung et al published a retrospective, multicenter study of 295 neonates with PA\/IVS that described major adverse cardiac events after the patients\u2019 first intervention. In the 279 patients that did undergo a first procedure, major adverse cardiac events occurred in 20% and the mortality rate was 8%. After a multivariate analysis, risk factors for major cardiac events included lower weight at the time of the first procedure as well as the presence of stenosis in two major coronary artery branches. Of note, patients with an aortopulmonary shunt or a ductal stent were more likely to require CPR, even when patients with RVDCC were removed from the statistical analysis. This highlights the fact that children with single-ventricle parallel physiology remain at high risk for myocardial ischemia. \r\n\r\n\r\nIdentifying RVDCC is thus one of the crucial first steps in managing children with PA\/IVS, as it will determine the safety of proceeding with RV decompression through opening the RVOT in the catheterization laboratory or with the use of cardiopulmonary bypass (CPB). In the setting of RVDCC, RV decompression leads to increased diastolic runoff from the coronaries into the RV, resulting in myocardial ischemia or infarction. At present, the gold-standard for diagnosing RVDCC is coronary angiography, with injection of the aorta and the RV, although echocardiography could potentially identify proximal stenosis or atresia. If RVDCC is ruled out, RV decompression is feasible with minimal risk of RV ischemia. Definitive management and prognosis of PA\/IVS will then depend on the size and function of the right-sided structures. More recently, several centers have been moving towards catheter-based interventions in the cardiac catheterization lab along with diagnostic angiogram versus traditional surgery, thereby avoiding CPB. Radiofrequency ablation and balloon dilation of the pulmonary valve may be attempted in patients with adequate RV size and function, as well as in those with less favorable anatomy with the goal of growing the right-sided structures. Patients with RVDCC and\/or those directed towards a single-ventricle palliation may undergo ductal stenting at the same time or soon after coronary angiography. \r\n\r\n\r\nPerioperative management of patients with RVDCC requires extra vigilance. Close monitoring of the ECG for signs of ischemia is essential, well as avoiding excessive vasodilation and hypovolemia. Vasodilation may be precipitated by fever, the use of anesthetic medications or vasodilators, such as nitroprusside or milrinone. Hypovolemia from excessive diuresis or gastrointestinal losses should be managed appropriately. Maintenance of RV preload and aggressive treatment of tachycardia and hypotension is critical to preventing myocardial ischemia and cardiac arrest. \r\n\r\n\r\nThe most appropriate initial step in the management of the patient in the stem is to define coronary anatomy and determine the presence of RVDCC. If RVDCC is confirmed, then any procedures that decompress the RV, such as radiofrequency perforation and ballooning of the pulmonary valve, are contraindicated. If the ductal anatomy is amenable to stent placement, this is appropriate to maintain pulmonary blood flow until the next stage of palliation. If ductal stenting is unsuccessful or not possible, an aorto-pulmonary shunt may be required or treatment with a continuous prostaglandin infusion.\r\n\r\n\r\n\r\n\r\n \r\nREFERENCES \r\n\r\nGleich S, Latham GJ, Joffe D, Ross FJ. Perioperative and Anesthetic Considerations in Pulmonary Atresia with Intact Ventricular Septum. Semin Cardiothorac Vasc Anesth<\/em>. 2018;22(3):256-264. doi:10.1177\/1089253217737180\r\n\r\n\r\nSpigel ZA, Qureshi AM, Morris SA, et al. Right Ventricle-Dependent Coronary Circulation: Location of Obstruction Is Associated with Survival. Ann Thorac Surg<\/em>. 2020;109(5):1480-1487. doi:10.1016\/j.athoracsur.2019.08.066\r\n\r\n\r\nCheung EW, Mastropietro CW, Flores S, et al. Procedural Outcomes of Pulmonary Atresia with Intact Ventricular Septum in Neonates: A Multicenter Study. Ann Thorac Surg<\/em>. 2023;115(6):1470-1477. doi:10.1016\/j.athoracsur.2022.07.055\r\n”,”hint”:””,”answers”:{“mnjaj”:{“id”:”mnjaj”,”image”:””,”imageId”:””,”title”:”A.\tDuctal stenting”},”exy12″:{“id”:”exy12″,”image”:””,”imageId”:””,”title”:”B.\tCoronary angiography”,”isCorrect”:”1″},”wqtbj”:{“id”:”wqtbj”,”image”:””,”imageId”:””,”title”:”C.\tRadiofrequency ablation of the pulmonary valve\r\n\r\n”}}}}}

{“questions”:{“q7fvy”:{“id”:”q7fvy”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Melissa Colizza, MD – Stollery Children\u2019s Hospital – Edmonton AB, Canada \r\n\r\nA one-day-old girl without prenatal care has been admitted to NICU due to cyanosis. Pulse oximetry demonstrates a SpO2 of 80% on the right hand and 89% on the left foot. Which of the following diagnoses is MOST likely in this patient?\r\n\r\n”,”desc”:”EXPLANATION \r\nCyanosis in the newborn child is a rather common finding with a broad differential diagnosis. Possible causes include simple acrocyanosis, pulmonary disorders such as respiratory distress syndrome or meconium aspiration, persistent pulmonary hypertension of the newborn (PPHN), distributive shock with poor peripheral perfusion, and cyanotic congenital heart disease (CHD). All newborns are routinely screened for critical congenital heart disease using two-site pulse oximetry, which includes both a pre-ductal (right hand) and a post-ductal (foot) S_{p<\/sub>O2<\/sub> reading. According to the CDC guidelines established in 2011, a Sp<\/sub>O2<\/sub> < 90%, Sp<\/sub>O2<\/sub> < 95% on three separate measurements, or a Sp<\/sub>O2<\/sub> difference of >3% between right hand and a foot warrant more extensive investigation. \r\n\r\n\r\nA pre-ductal saturation that is more than 3% or higher than the post-ductal saturation is known as \u201cdifferential cyanosis\u201d. This can be seen in two common scenarios in which there is ductal-dependent systemic blood flow. The first scenario involves ductal dependent systemic blood flow along with some degree of antegrade blood flow through the aortic valve, such as in severe coarctation of the aorta, interrupted aortic arch, or hypoplastic left heart syndrome. In these conditions, lower body perfusion is due to the shunting of pulmonary arterial blood into the descending aorta via the patent ductus arteriosus (PDA). The second scenario occurs as a result of suprasystemic pulmonary arterial pressure or high pulmonary vascular resistance producing right-to-left shunting of blood from the pulmonary artery to the descending aorta via the PDA.\r\n\r\n\r\n\u201cReverse differential cyanosis\u201d (RDC) is defined as a pre-ductal Sp<\/sub>O2<\/sub> that is lower<\/em> than the post-ductal Sp<\/sub>O2<\/sub>. This occurs in situations when some quantity of oxygenated blood from the pulmonary venous return enters the descending aorta via the PDA, while deoxygenated blood is simultaneously perfusing the upper body via the pre-ductal vessels. Classically, RDC is seen in the setting of D-transposition of the great arteries (D-TGA) with one or more of the following: (1) severe pulmonary hypertension; (2) pre-ductal coarctation of the aorta, or (3) interrupted aortic arch (IAA). In D-TGA, the right ventricle ejects deoxygenated blood into the aorta, whereas oxygenated blood exits the left ventricle into the pulmonary artery. In the setting of severe pulmonary hypertension, preductal coarctation of the aorta, or interrupted aortic arch, oxygenated blood preferentially enters the descending aorta via the PDA, while the head and neck branches of the aortic arch are perfused with deoxygenated blood from the right ventricle, leading to RDC. (Fig. 1) \r\n\r\n\r\n\r\nFig.1. In the setting of D-TGA with coarctation, interrupted aortic arch or severe pulmonary hypertension, oxygenated blood preferentially streams from the PDA to the descending aorta, leading to reverse differential cyanosis. \r\n\r\n\r\nReverse differential cyanosis has also been described in patients with total anomalous pulmonary venous connection (TAPVC). In supracardiac TAPVC, the persistence of two fetal circulatory shunts, the PDA and patent foramen ovale (PFO), allows for differential streaming of blood. Blood streams from the superior vena cava (SVC), which has a higher oxygen saturation due to mixing of systemic venous return with pulmonary venous blood, into the right ventricle (RV), while blood from the inferior vena cava (IVC) streams into the left ventricle (LV) via the PFO. A 2008 case report by Yap et al describes a newborn with RDC in the context of supracardiac TAPVC. In this patient, the left pulmonary veins drained into the innominate vein via a vertical vein, while the right pulmonary veins entered the SVC directly. A transthoracic echocardiogram demonstrated that the SVC blood return with a higher oxygen saturation preferentially entered the RV before streaming into the descending aorta via the PDA. The blood returning from the IVC with lower oxygen saturation preferentially streamed into the left atrium through a moderate ASD, then into the LV, and finally to the aorta. Thus, the ascending aorta and aortic arch were supplied by relatively deoxygenated blood (Figure 2). Chow et al also published a case series of two neonates with obstructed TAPVC presenting with RDC. Another lesion which may cause RDC is an anomalous right subclavian artery that is connected by the ductus to the right pulmonary artery. Conversely, a newborn with infracardiac TAPVC could present with differential cyanosis due to IVC return with a higher oxygen saturation streaming into the LV via the PFO and then entering the aorta and head\/neck vessels. \r\n\r\n\r\n \r\n\r\nFig.2. In supracardiac TAPVC, SVC blood return of higher oxygen saturation streams into the RV and then across the PDA into the descending aorta, while the deoxygenated IVC return streams across the PFO to the LV and is ejected into the upper body, producing reverse differential cyanosis. \r\n\r\n\r\nThe correct answer choice for the patient described in the stem presenting with RDC is TAPVC. Both Hypoplastic Left Heart Syndrome (HLHS) and PPHN would give rise to differential cyanosis as opposed to RDC and are therefore incorrect. \r\n\r\n\r\n\r\n \r\nREFERENCES \r\n\r\nYap SH, Anania N, Alboliras ET, Lilien LD. Reversed differential cyanosis in the newborn: a clinical finding in the supracardiac total anomalous pulmonary venous connection. Pediatr Cardiol<\/em>. 2009;30(3):359-362. doi:10.1007\/s00246-008-9314-0\r\n\r\n\r\nChow PC, Chen RHS, Rocha BA, Yam NLH. Reversed differential cyanosis in two neonates with obstructed supracardiac total anomalous pulmonary venous drainage. Res Pediatr Neonatol<\/em>. 2019; 3(5). RPN.000574. doi: 10.31031\/RPN.2019.03.000574\r\n\r\n\r\nOster ME, Aucott SW, Glidewell J et al. Lessons Learned From Newborn Screening for Critical Congenital Heart Defects. Pediatrics<\/em>. 2016 May;137(5): e20154573. doi: 10.1542\/peds.2015-4573. \r\n\r\n”,”hint”:””,”answers”:{“o66br”:{“id”:”o66br”,”image”:””,”imageId”:””,”title”:”A)\tHypoplastic Left-Heart Syndrome “},”l1isb”:{“id”:”l1isb”,”image”:””,”imageId”:””,”title”:”B)\tSupracardiac Total Anomalous Pulmonary Venous Connection”,”isCorrect”:”1″},”s6n5p”:{“id”:”s6n5p”,”image”:””,”imageId”:””,”title”:”C)\tPersistent pulmonary hypertension of the newborn\r\n\r\n”}}}}}}