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

{“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”}}}}}}

{“questions”:{“jbe99”:{“id”:”jbe99″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Meera Gangadharan, MD, FASA, FAAP – University of Texas at Houston, McGovern Medical School, Children\u2019s Memorial Hermann Hospital \r\n\r\nA 3-week-old boy is admitted to the cardiac intensive care unit with acute congestive heart failure and generalized hypotonia. Transthoracic echocardiography demonstrates a dilated left ventricle with severely diminished function. Additionally, an ECG indicates a prolonged QTc interval, and a complete blood count is significant for neutropenia. Which of the following X-linked conditions is MOST likely to be present in this patient? \r\n”,”desc”:”EXPLANATION \r\nBarth syndrome is an X-linked recessive condition that classically presents with cardiomyopathy, poor growth, neutropenia, small stature, and skeletal myopathy. It is a rare condition currently estimated to affect one in a million males worldwide. Due to its X-linked recessive classification, it almost exclusively affects males. Neutropenia may be cyclical, intermittent, or sustained and increases the risk of bacterial infections, the second most common cause of death after cardiomyopathy. Skeletal myopathy is usually non-progressive and typically affects the proximal limb muscles. \r\n\r\n\r\nPatients commonly present during infancy with signs and symptoms of acute dilated cardiomyopathy. In male fetuses, hydrops fetalis, cardiomyopathy, and intrauterine growth fetuses are also typical of Barth syndrome. Often there is a family history of multi-generational fetal loss and\/or still births of males. Often, a viral illness is the precipitating event that brings an infant to the hospital with symptoms of heart failure, making the diagnosis of Barth syndrome less obvious. Though dilated cardiomyopathy is the most common cardiac condition seen in young infants and children with Barth Syndrome, hypertrophic, restrictive, and left ventricular non-compaction cardiomyopathy may also be present in some. Patients with Barth syndrome are also at risk for ventricular arrhythmias and sudden death. A prolonged QTc interval on an electrocardiogram is evident in 25%-75% of patients. Infancy and early childhood are periods of high risk for cardiac death. Older children appear to have more stable cardiac function.\r\n\r\n\r\nBarth syndrome is caused by a genetic defect in the TAFAZZIN gene, located on chromosome Xq28, which encodes an enzyme involved in cardiolipin remodeling. Cardiolipin (CL) is a phospholipid present on the inner mitochondrial membrane that is essential for important functions of the respiratory chain. As a result of the genetic defect, abnormal enzyme activity results in an accumulation of monolysocardiolipin (MCL). An elevation in the MCL:CL ratio is thus present in the blood and tissues of patients with Barth syndrome. An elevated MCL:CL ratio approaches 100% sensitivity and specificity for Barth syndrome. Patients are thus at increased risk of lactic acidosis and hypoglycemia due to mitochondrial dysfunction.\r\n\r\n\r\nManagement of heart failure in Barth Syndrome follows standard guidelines. Transplant is a viable option for end-stage heart failure. Morbidity and mortality after cardiac transplantation is equivalent in Barth syndrome and non-Barth syndrome patients with dilated cardiomyopathy. Skeletal muscle myopathy is generally managed with physical therapy, exercise regimens and devices to aid mobility. Although there are no currently available therapies for Barth Syndrome, elamipretide is a medication that is being reviewed by the Food and Drug Administration to treat Barth syndrome. This peptide molecule localizes to the inner mitochondrial membrane and enhances ATP synthesis.\r\n\r\n\r\nThe pre-anesthetic evaluation of patients with Barth syndrome should include a complete blood count, glucose, and carnitine levels. A recent electrocardiogram and echocardiogram should be reviewed prior to surgery. Excessive preoperative fasting should also be avoided due to the risk of hypoglycemia and lactic acidosis. Succinylcholine is contraindicated due to skeletal myopathy. Cardiac medications should be managed as for any other patient and the usual precautions should be taken if a rhythm management device is present. Sterility, aseptic technique and prophylactic antibiotics are especially important in neutropenic patients. Postoperative ventilation may be necessary for patients with significant skeletal muscle weakness. \r\n\r\n\r\nChoice A is the correct answer due to the presentation of cardiomyopathy, hypotonia, prolonged QTc, and neutropenia, all features of Barth syndrome. Alport syndrome is a condition in which there is hearing loss and renal disease. The only cardiovascular manifestation is hypertension, secondary to renal disease. X-linked dominant, autosomal dominant and autosomal recessive forms have been described. Thrombocytopenia is associated with Alport syndrome, versus the neutropenia that is associated with Barth syndrome. Duchenne muscular dystrophy is an X-linked recessive disorder with cardiomyopathy, skeletal myopathy, and smooth muscle myopathy. Cardiac failure usually occurs later during this disease and is very unlikely to manifest in infancy as demonstrated in the stem.\r\n\r\n\r\n\r\n \r\nREFERENCES \r\n\r\nTaylor C, Rao ES, Pierre G, et al. Clinical presentation and natural history of Barth Syndrome: An overview. J Inherit Metab Dis<\/em>. 2022;45(1):7-16. doi:10.1002\/jimd.12422\r\n\r\n\r\nThompson R, Jeffries J, Wang S, et al. Current and future treatment approaches for Barth syndrome. J Inherit Metab Dis<\/em>. 2022; 45(1):17-28. doi: 10.1002\/jimd.12453.\r\n\r\n\r\nLi Y, Godown J, Taylor CL, Dipchand AI, Bowen VM, Feingold B. Favorable outcomes after heart transplantation in Barth syndrome. J Heart Lung Transplant<\/em>. 2021; 40(10):1191-1198. doi: 10.1016\/j.healun.2021.06.017.\r\n\r\n\r\nBaum VC, O\u2019Flaherty JE. Barth syndrome. In: Baum VC, O\u2019Flaherty JE, eds. Anesthesia for Genetic, Metabolic and Dysmorphic Syndromes of Childhood<\/em>. 3rd ed. Philadelphia, PA: Wolters Kluwer; 2015:50-51.\r\n\r\n\r\nBaum VC, O\u2019Flaherty JE. Alport syndrome. In: Baum VC, O\u2019Flaherty JE, eds. Anesthesia for Genetic, Metabolic and Dysmorphic Syndromes of Childhood<\/em>. 3rd ed. Philadelphia, PA: Wolters Kluwer; 2015:28-29.\r\n\r\n\r\nBaum VC, O\u2019Flaherty JE. Duchenne muscular dystrophy. In: Baum VC, O\u2019Flaherty JE, eds. Anesthesia for Genetic, Metabolic and Dysmorphic Syndromes of Childhood<\/em>. 3rd ed. Philadelphia, PA: Wolters Kluwer; 2015:125-127.\r\n”,”hint”:””,”answers”:{“rb34e”:{“id”:”rb34e”,”image”:””,”imageId”:””,”title”:”A.\tBarth Syndrome”,”isCorrect”:”1″},”f5yvq”:{“id”:”f5yvq”,”image”:””,”imageId”:””,”title”:”B.\tAlport Syndrome”},”l3buy”:{“id”:”l3buy”,”image”:””,”imageId”:””,”title”:”C.\tDuchenne muscular dystrophy”}}}}}

{“questions”:{“g4glk”:{“id”:”g4glk”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Author: Meera Gangadharan, MD, FASA, FAAP – University of Texas at Houston, McGovern Medical School, Children\u2019s Memorial Hermann Hospital \r\nA 6-year-old girl with a history of orthotopic heart transplantation two years prior is undergoing routine cardiac catheterization and endomyocardial biopsy. After induction of anesthesia, the patient develops a regular, narrow-complex supraventricular tachycardia with a rate of 200 bpm and blood pressure of 85\/43. Which of the following modifications in the dose of adenosine is MOST appropriate to treat this patient?”,”desc”:”EXPLANATION \r\nThe cardiac allograft demonstrates altered physiology due to denervation of the autonomic nervous system. Parasympathetic innervation is lost making the resting heart rate slightly higher than normal. Holter studies have demonstrated higher minimum heart rates, similar maximal heart rates, and decreased heart rate variability in patients after heart transplantation. Because of the loss of the baroreceptor reflex, the transplanted heart does not make rapid compensatory adjustments in heart rate. The transplanted heart has been described as \u201cpreload dependent\u201d because it relies on Frank-Starling forces and end-diastolic volume to maintain cardiac output in the absence of the ability to alter the heart rate rapidly. Conversely, the intrinsic properties of the cardiac muscle are preserved.\r\n\r\n\r\nAdenosine, a drug commonly used to treat supraventricular tachycardia (SVT), is a purine nucleoside that binds to G protein coupled receptors in the heart. In the sinus node, activation of these receptors decreases the rate of spontaneous depolarization by reducing intracellular cyclic AMP levels, leading to a decreased heart rate. In the atrioventricular (AV) node, activation of these receptors results in the inhibition of L-type calcium channels, which in turn decreases conduction velocity and leads to AV block. \r\n\r\n\r\nThe sinus node and AV node of the transplanted heart are hypersensitive to the pharmacologic effects of adenosine as compared to the native, non-transplanted heart. A 1990 study by Ellenbogen et al demonstrated that the sinus node and the AV node in patients who had undergone heart transplantation exhibited an exaggerated response to adenosine administration. Twenty-eight heart transplant patients and nine patients without heart transplantation were administered increasing doses of adenosine during an electrophysiology study. The study demonstrated that the sinus node cycle length was significantly greater and the duration of the chronotropic effect of adenosine was prolonged in the heart transplant patients. Similar results were demonstrated in the AV node. \r\n\r\n\r\nIn a small series of patients undergoing pharmacologic stress testing with adenosine, Toft et al demonstrated that 4% of non-transplanted heart patients developed AV block during the test. Based on this study and others, the administration of adenosine to cardiac transplant recipients is often considered a relative contraindication due to the possibility of prolonged heart block. However, more recent evidence suggests that this caution may have been overstated.\r\n\r\n\r\nA single-center, prospective study by Flyer et al (2017) investigated the pharmacologic effects of adenosine in stable heart transplant patients who were undergoing cardiac catheterization. Electrophysiological measurements were taken during the administration of increasing doses of adenosine in eighty patients between the ages of six months and 25 years. Adenosine dosing was initiated at 12.5 mcg\/kg and increased to 25mcg\/kg, 50mcg\/kg, 100mcg\/kg and 200mcg\/kg. Patients over sixty kilograms received 0.8 mg, 1.5 mg, 3 mg, 6 mg, and 12 mg of adenosine incrementally. Dose escalation was stopped when AV block or clinically significant asystole occurred (i.e. sinus pause or AV block greater than twelve seconds). The results indicated that a dose of 12.5 mcg\/kg did not cause AV block in any patient. Twelve percent developed AV block after a dose of 25mcg\/kg, 31% after 50 mcg\/kg, 72% after 100 mcg\/kg, and 96% after 200mcg\/kg. None of the patients needed rescue pacing after adenosine administration. The mean duration of adenosine effect was 4.3 seconds, and the longest duration was 8.4 seconds. There was no association between the dose of adenosine needed to produce AV block and the time from the heart transplant. The authors concluded that adenosine is safe and efficacious in the stable heart transplant population. They suggested that the initial adenosine dose should be 25 mcg\/kg, which is a quarter of the dose recommended in the PALS and ACLS algorithms to treat supraventricular tachycardia. If the desired effect is not achieved, the dose should be increased gradually. \r\n\r\n\r\nFor the patient in the stem, the initial dose of adenosine used to treat supraventricular tachycardia should be decreased. The 2023 International Society of Heart and Lung Transplantation (ISHLT) guideline for the care of heart transplant recipients recommends an initial dose of 25 mcg\/kg (or 1.5 mg in patients over 60 kg) in conjunction with a gradual dose increase until the desired clinical response is achieved for administration of the drug adenosine.\r\n\r\n\r\n\r\n \r\nREFERENCES \r\n\r\nKleiman Z, Zabala LM. Post orthotopic cardiac transplantation. In: Berenstain LK, Spaeth JP (Eds). Congenital Cardiac Anesthesia: A Case-Based Approach<\/em>. Cambridge University Press, Cambridge, UK; 2021. 290-298.\r\n\r\n\r\n\r\nToft J, Mortensen J, Hesse B. Risk of atrioventricular block during adenosine pharmacologic stress testing in heart transplant recipients. Am J Cardiol<\/em>. 1998;82(5):696-697, A9. doi:10.1016\/s0002-9149(98)00392-0\r\n\r\n\r\nEllenbogen KA, Thames MD, DiMarco JP, Sheehan H, Lerman BB. Electrophysiological effects of adenosine in the transplanted human heart. Evidence of super sensitivity. Circulation<\/em>. 1990;81(3):821-828. doi:10.1161\/01.cir.81.3.821\r\n\r\n\r\nFlyer JN, Zuckerman WA, Richmond ME, et al. Prospective Study of Adenosine on Atrioventricular Nodal Conduction in Pediatric and Young Adult Patients After Heart Transplantation. Circulation<\/em>. 2017;135(25):2485-2493. doi:10.1161\/CIRCULATIONAHA.117.028087\r\n\r\n\r\nVelleca A, Shullo MA, Dhital K, et al. The International Society for Heart and Lung Transplantation (ISHLT) guidelines for the care of heart transplant recipients. J Heart Lung Transplant<\/em>. 2023; 42(5): e1-e141. doi.org\/10.1016\/j.healun.2022.10.015\r\n\r\n”,”hint”:””,”answers”:{“iknc0”:{“id”:”iknc0″,”image”:””,”imageId”:””,”title”:”A)\tIncrease”},”m5sec”:{“id”:”m5sec”,”image”:””,”imageId”:””,”title”:”B)\tDecrease”,”isCorrect”:”1″},”mzhfp”:{“id”:”mzhfp”,”image”:””,”imageId”:””,”title”:”C)\tNo change”}}}}}