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

{“questions”:{“4x49p”:{“id”:”4x49p”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: J. O\u2019Doherty, MB, ChB AND M. Gangadharan, MD, FAAP, FASA – Children\u2019s Memorial Hermann Hospital, University of Texas Health Science Center, Houston, TX \r\n\r\nA full-term newborn girl is diagnosed with truncus arteriosus. A transthoracic echocardiogram reveals a main pulmonary trunk arising from the truncus arteriosus, which divides into right and left pulmonary arteries. According to the Collett and Edwards classification, which type of truncus arteriosus does this child have? “,”desc”:”EXPLANATION \r\nTruncus arteriosus (TA) is a cyanotic congenital cardiac abnormality characterized by a single arterial trunk supplying the aorta, pulmonary arteries, and coronary arteries. This rare condition represents one to three percent of all cardiac defects. In almost all cases, a large ventricular septal defect is present in the infundibular septum, along with a single truncal valve that is most commonly tri-leaflet.\r\n\r\n\r\nThe Collett and Edwards classification (see Figure 1) categorizes TA into four types based on the pattern of origin of the pulmonary arteries, which are as follows: \r\n\u2022\tType I is characterized by a main pulmonary artery originating from the truncus, which then divides into the left and right branch pulmonary arteries. \r\n\u2022\tType II is characterized by an absent main pulmonary artery segment. Instead, the right and left pulmonary arteries arise separately from the posterior aspect of the truncus with their origins close to each other. \r\n\u2022\tType III is identical to Type II, except with widely separated origins of the pulmonary arteries. \r\n\u2022\tType IV is now recognized as a distinct clinical diagnosis, pulmonary atresia with major aortopulmonary collaterals, and is no longer considered to be a form of TA. \r\n\r\n\r\nThe classification system proposed by Van Praagh and Van Praagh (see Figure 1) divides TA into four types, including the following: \r\n\u2022\tType A1, which is identical to Collett and Edwards Type I TA. \r\n\u2022\tType A2, which mirrors Collett and Edwards Type II and III TA. \r\n\u2022\tType A3 is characterized by one pulmonary artery arising from the truncus, while a second pulmonary artery is supplied by the ductus arteriosus or originates from a systemic artery. \r\n\u2022\tType A4 includes cases with aortic arch abnormalities including hypoplasia, coarctation, and\/or interruption. \r\n\r\n\r\nFigure 1: Classification Systems of Truncus Arteriosus\r\n\r\n \r\n\r\n\r\n\r\nIt is also important to characterize the cardiac anatomy of these patients, including the anatomy and function of the truncal valve and the arrangement of the coronary arteries, as these features can significantly impact surgical outcomes. The truncal valve may be normal, regurgitant, or, rarely, stenotic. The truncal valve is tri-leaflet in most cases of TA, but can also be quadricuspid, bicuspid, pentacuspid, or unicomissural, in order of decreasing frequency. Truncal valves with moderate to severe regurgitation are usually repaired at the time of complete surgical correction.\r\n\r\n\r\nIn most cases, the right and left coronary arteries arise from their respective ostia on the right anterolateral and left posterolateral surface of the truncus. However, coronary artery anomalies are frequently associated with TA. Approximately 27% of patients have a left dominant system. The left anterior descending artery is often small, and the right coronary artery conal branch is more prominent, with large branches supplying the right ventricular outflow tract. This is important because the repair often involves the placement of a valved conduit from the right ventricle to the pulmonary artery.\r\n\r\n\r\nVariations in coronary anatomy can significantly impact surgical outcomes. In a recent single-center, retrospective review, 34 of 107 patients undergoing truncus arteriosus repair had at least one coronary lesion, which was defined as either a single coronary, ostial stenosis, intramural coronary course or juxta commissural origin of coronaries. Patients with one or two coronary lesions had similar 5-year survival, 80% and 83%, respectively. However, patients with three coronary lesions had a 5-year survival of 24% (p = 0.003). Furthermore, there was a trend towards improved 5-year survival if interventions were performed to treat coronary artery abnormalities. \r\n\r\n\r\nGenetic syndromes associated with truncus arteriosus are another consideration. A significant proportion of patients, 30 to 40 %, will have Chromosome 22q11.2 Deletion syndrome. These patients are 2.4 times more likely to have an aortic arch anomaly than those without this syndrome. Right aortic arch with mirror-image branching represents another common finding, occurring in 21 to 36 % of patients with TA. The ductus arteriosus is absent in 50% of patients with TA. However, the ductus arteriosus is typically present in patients with TA and a hypoplastic aortic arch anomaly. \r\n\r\n\r\nThe patient described in the vignette has a main pulmonary artery trunk arising from the truncus which divides into right and left pulmonary arteries, which is classified as Collett and Edwards Type I truncus arteriosus.\r\n\r\n\r\n\r\n \r\nREFERENCES \r\n\r\nParikh R, Eisses M, Latham GJ, Joffe DC, Ross FJ. Perioperative and Anesthetic Considerations in Truncus Arteriosus. Semin Cardiothorac Vasc Anesth<\/em>. 2018;22(3):285-293. doi:10.1177\/1089253218778826\r\n\r\n\r\nMenon SC, Cabalka AK, Dearani JA. Truncus Arteriosus. In: Shaddy RE, Penny DJ, Cetta F, Feltes TF, Mital S, eds. Moss and Adams\u2019 Heart Disease in infants, children and adolescents including the fetus and young adult<\/em>. 10th Edition. Philadephia, PA. Wolters Kluwer; 2022: 1009-1019\r\n\r\n\r\nBonilla-Ramirez C, Ibarra C, Binsalamah ZM, et al. Coronary Artery Anomalies Are Associated With Increased Mortality After Truncus Arteriosus Repair. Ann Thorac Surg<\/em>. 2021;112(6):2005-2011. doi:10.1016\/j.athoracsur.2020.08.082\r\n”,”hint”:””,”answers”:{“uho7t”:{“id”:”uho7t”,”image”:””,”imageId”:””,”title”:”A.\tType I”,”isCorrect”:”1″},”8cl68″:{“id”:”8cl68″,”image”:””,”imageId”:””,”title”:”B.\tType II”},”863q9″:{“id”:”863q9″,”image”:””,”imageId”:””,”title”:”C.\tType III”},”jpklg”:{“id”:”jpklg”,”image”:””,”imageId”:””,”title”:”D.\tType IV “}}}}}

{“questions”:{“p25o8”:{“id”:”p25o8″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Morgan Ulloa, MD AND Kristin Richards, MD; University of Southern California, Children\u2019s Hospital Los Angeles, Los Angeles, CA \r\nMeera Gangadharan, MBBS, FAAP, FASA, UT Health, Children\u2019s Memorial Hermann Hospital, Houston, Texas \r\n\r\nA 14-year-old boy with a history of orthotopic heart transplantation receives the following medications: mycophenolate mofetil, tacrolimus, and prednisone. A recent comprehensive metabolic panel reveals an increase in his plasma creatinine from baseline. Which of the following immunosuppressant medications is MOST likely responsible for this laboratory finding?\r\n”,”desc”:”EXPLANATION \r\nTacrolimus, also known as Prograf, FK506, or TAC, is a macrolide that is commonly utilized for the maintenance of immunosuppression in heart transplant recipients. The immunosuppressive properties of tacrolimus stem from its selective inhibition of calcineurin, which leads to decreased proliferation of T-lymphocytes and decreased production of interleukin 2 (IL-2), interleukin 3 (IL-3), interleukin 4 (IL-4), interferon gamma, CD40L, GM-CSF, and tumor necrosis factor alpha (TNF-alpha). It is a lipophilic medication that is predominantly metabolized by cytochrome P-450 CYP3A enzymes in the liver. Tacrolimus is eliminated via biliary excretion. The elimination half-life is dependent on the formulation (immediate-release versus extended-release). \r\n\r\nTacrolimus is known to be nephrotoxic. Renal injury is more likely with higher doses of the medication, liver disease, inhibition of cytochrome P-450 CYP3A (notably by grapefruit) leading to higher plasma levels of the medication and its active metabolites, pre-existing renal disease, and the concomitant use of other nephrotoxic agents such as non-steroidal anti-inflammatory drugs. The nephrotoxic effects can lead to either acute kidney injury, which can often be reversed with a reduction in the dose of the drug, or chronic progressive kidney disease, which may be irreversible and lead to end-stage renal disease. \r\n\r\nThe mechanism of tacrolimus nephrotoxicity is not entirely known but is believed to be similar to cyclosporine, another calcineurin inhibitor, with a longer history of use clinically and known nephrotoxic properties. The acute nephrotoxic effects of both medications are thought to be due to endothelial cell dysfunction in afferent and efferent glomerular arterioles, leading to vasoconstriction that limits renal blood flow and glomerular filtration. Pathological examination of renal tissue in patients with chronic progressive renal disease has demonstrated arteriopathy, tubular damage, glomerular damage, and interstitial fibrosis. These findings may be responsible for or worsen associated pathologic states, such as hypertension, that may then compound existing renal disease. Thrombotic microangiopathy is an additional mechanism by which tacrolimus may cause renal injury.\r\n\r\nThe primary approach to minimizing tacrolimus-associated nephrotoxicity is by limiting exposure to the medication. This can be accomplished with dose reduction, the addition of adjunctive immunosuppressive medications such as mycophenolate mofetil, avoidance of medications and substances that inhibit tacrolimus metabolism in the liver, avoidance of additional nephrotoxic agents and the management of physiologic states that may worsen renal disease such as hypertension. \r\n\r\nOther important side effects of tacrolimus include metabolic disturbances, such as hyperkalemia, hypophosphatemia, hypomagnesemia, metabolic acidosis secondary to reduced renal acid excretion, hypercalciuria, neurotoxicity (headaches, tremors, neuropathy, encephalopathy, seizures, posterior reversible encephalopathy syndrome), glucose intolerance, hyperuricemia, and gout. There is a published case report of bronchiolitis obliterans, which the authors believed was caused by tacrolimus in a 19-month-old heart transplant recipient. \r\n\r\nMycophenolate mofetil (MMF, CellCept, Myfortic), like its predecessor azathioprine, is an anti-metabolite medication that acts as a reversible, non-competitive inhibitor of inosine monophosphate dehydrogenase, thus inhibiting the synthesis of GMP and T cell and B cell function. Mycophenolate mofetil is used to decrease the dose of calcineurin inhibitors and, thereby, calcineurin inhibitor toxicity. The main adverse effects of MMF are hematologic (leukopenia, anemia, and thrombocytopenia) and gastrointestinal (diarrhea and vomiting).\r\n\r\nPrednisone is a synthetic glucocorticoid pro-drug that is metabolized in the liver to prednisolone. Prednisone is utilized as an immunosuppressant medication and an anti-inflammatory medication. Although there are many undesirable side effects of glucocorticoid therapy, prednisone is not strongly associated with nephrotoxicity.\r\n\r\nThe correct answer is B. Renal toxicity is a major risk factor associated with the use of calcineurin inhibitor-type medications tacrolimus and cyclosporin. MMF and steroids are generally not associated with renal injury.\r\n\r\n\r\n\r\n\r\n \r\nREFERENCES \r\nHardinger K, Magee CC. Pharmacology of calcineurin inhibitors. In UpToDate, Connor RF (Ed), Wolters Kluwer. https:\/\/www.uptodate.com\/contents\/pharmacology-of-calcineurin-inhibitors Accessed on October 2, 2024.\r\n\r\nHardinger K, Brennan DC, Lam AQ. Cyclosporine and tacrolimus nephrotoxicity. In UpToDate, Connor RF (Ed), Wolters Kluwer. https:\/\/www.uptodate.com\/contents\/cyclosporine-and-tacrolimus-nephrotoxicity Accessed on October 3, 2024.\r\n\r\nKirpalani A, Teoh CW, Ng VL, Dipchand AI, Matsuda-Abedini M. Kidney disease in children with heart or liver transplant. Pediatr Nephrol<\/em>. 2021;36(11):3595-3605. doi:10.1007\/s00467-021-04949-5\r\n\r\nKarim F, Misra A, Sehgal S. Bronchiolitis obliterans organising pneumonia secondary to tacrolimus toxicity in a pediatric cardiac transplant recipient. Cardiol Young<\/em>. 2023;33(4):630-632. doi:10.1017\/S1047951122002049\r\n\r\nCrowley KL, Webber S. Immunosuppressive agents in pediatric heart transplantation. In: Munoz R, da Cruz EM, Vetterly CG, Cooper DS, Berry D, Eds. Handbook of Pediatric Cardiovascular Drugs<\/em>. 2nd Edition. London, UK: Springer-Verlag; 2014: pp 329-363.\r\n\r\n”,”hint”:””,”answers”:{“cvv25”:{“id”:”cvv25″,”image”:””,”imageId”:””,”title”:”A.\tMycophenolate mofetil “},”8xciu”:{“id”:”8xciu”,”image”:””,”imageId”:””,”title”:”B.\tTacrolimus “,”isCorrect”:”1″},”bqq8q”:{“id”:”bqq8q”,”image”:””,”imageId”:””,”title”:”C.\tPrednisone”}}}}}

{“questions”:{“p5z3o”:{“id”:”p5z3o”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Clementine Vo, DO \u2013 Texas Children\u2019s Hospital\/Baylor College of Medicine, Houston, TX, USA AND\r\nDestiny F. Chau, MD – Arkansas Children\u2019s Hospital\/University of Arkansas for Medical Sciences, Little Rock, AR, USA \r\n\r\nA 16-year-old girl with a history of an unbalanced atrioventricular canal palliated with the Fontan procedure presents for cardiac catheterization due to ascites. Magnetic resonance imaging of the liver demonstrates hepatic fibrosis, and laboratory studies reveal hypoalbuminemia and elevated stool anti-trypsin levels. Which of the following diagnoses is the MOST likely cause of these clinical findings? \r\n”,”desc”:”EXPLANATION \r\nThe Fontan physiology creates a state of chronic venous hypertension that can lead to multi-system organ dysfunction, characterized by protein-losing enteropathy (PLE), plastic bronchitis, and Fontan-associated liver disease. PLE and plastic bronchitis are associated with lymphatic dysfunction and the leakage of protein-rich lymph fluid into luminal spaces adjacent to lymphatic vessels. The leakage of proteinaceous fluid into the intestinal lumen results in enteric protein loss, also known as PLE. Leakage of proteinaceous material into the bronchial tree causes plastic bronchitis with the formation of bronchial casts. Symptoms of plastic bronchitis include dyspnea, cough, wheezing, and, in severe cases, respiratory failure due to airway obstruction from the casts. The diagnosis is confirmed by bronchoscopy.\r\n\r\nSigns and symptoms of PLE include progressive central and peripheral edema, ascites, and often diarrhea. PLE affects up to 13% of Fontan patients, typically within ten years of the Fontan procedure. Factors predisposing to PLE include altered intestinal mucosal perfusion, low cardiac output, a selective increase in mesenteric vascular resistance, a proinflammatory state altering gut membrane permeability, and low heparan sulfate proteoglycans in the enterocyte membrane resulting in reduced enteral protein transport and increased luminal protein loss. Protein loss results in severe hypoalbuminemia and low serum oncotic pressure, leading to edema. The gold standard for PLE diagnosis is an elevated 24-hour stool alpha-1 antitrypsin clearance. PLE may also be diagnosed with a single stool sample with an elevated alpha-1 antitrypsin level concurrent with serum hypoalbuminemia and generalized edema with no other cause. Chronic protein loss is associated with a multitude of clinical sequelae, such as poor tissue integrity and impaired wound healing, coagulation factor deficiency resulting in coagulopathy and thromboembolic complications, hypoalbuminemia leading to secondary hypocalcemia, and low immunoglobulin levels resulting in immunodeficiency.\r\n\r\nPLE management focuses on reducing chronic venous hypertension by optimizing Fontan hemodynamics and improving nutritional intake. Medical management includes diuretics to reduce fluid overload, albumin to restore oncotic pressure, steroids to reduce inflammation, aldosterone antagonists and\/or heparin to stabilize the proteoglycan layer of the gut, and pulmonary vasodilators to reduce chronic venous congestion. Lymphatic interventions may reroute the lymphatic flow to provide a measure of symptomatic relief and improvement in quality of life. Heart transplantation is the last resort and appears to be effective for symptom relief. However, patients with PLE are often poor candidates due to chronic protein wasting and poor nutritional status and may not survive the waiting period or the transplantation procedure. The prognosis is grim, with 50% mortality within the first five years after diagnosis. \r\n\r\nThe patient in the stem has elevated stool alpha-antitrypsin, hypoalbuminemia, and ascites, which are diagnostic for PLE. Therefore, PLE is the most likely cause of the clinical presentation described in the stem. Plastic bronchitis is not the correct answer, as it is characterized by respiratory symptoms and the presence of airway casts. Although hypoalbuminemia and ascites are both signs of hepatic dysfunction in Fontan-associated liver disease (FALD), the MRI demonstrates fibrosis rather than cirrhosis, a classic finding in FALD. Additionally, FALD is not usually associated with significant hepatic synthetic impairment.\r\n\r\n\r\n \r\nREFERENCES \r\nRychik J, Atz AM, Celermajer DS, et al. Evaluation and management of the child and adult with Fontan circulation: A scientific statement from the American Heart Association. Circulation<\/em>. 2019;140(6):e234-e284. \r\n\r\nMackie AS, Veldtman GR, Thorup L, Hjortdal VE, Dori Y. Plastic bronchitis and protein-losing enteropathy in the Fontan patient: Evolving understanding and emerging therapies. Can J Cardiol<\/em>. 2022;38(7):988-1001. doi:10.1016\/j.cjca.2022.03.011\r\n\r\nJohn AS, Johnson JA, Khan M, Driscoll DJ, Warnes CA, Cetta F. Clinical outcomes and improved survival in patients with protein-losing enteropathy after the Fontan operation. J Am Coll Cardiol<\/em>. 2014;64(1):54-62. doi: 10.1016\/j.jacc.2014.04.025. PMID: 24998129.\r\n\r\nStout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA\/ACC guideline for the management of adults with congenital heart disease: Executive summary: A report of the American College of Cardiology\/American Heart Association task force on clinical practice guidelines [published correction appears in J Am Coll Cardiol. 2019.14;73(18):2361]. J Am Coll Cardiol<\/em>. 2019;73(12):1494-1563. doi:10.1016\/j.jacc.2018.08.1028\r\n\r\n”,”hint”:””,”answers”:{“1jyk6”:{“id”:”1jyk6″,”image”:””,”imageId”:””,”title”:”A.\tPlastic bronchitis”},”bedeu”:{“id”:”bedeu”,”image”:””,”imageId”:””,”title”:”B.\tProtein-losing enteropathy”,”isCorrect”:”1″},”rz5a2″:{“id”:”rz5a2″,”image”:””,”imageId”:””,”title”:”C.\tFontan-associated liver disease”}}}}}

{“questions”:{“8r6p9”:{“id”:”8r6p9″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Meera Gangadharan, MBBS, FAAP, FASA – Children\u2019s Memorial Hermann Hospital, McGovern Medical School, Houston, TX AND Destiny F. Chau, MD – Arkansas Children\u2019s Hospital\/University of Arkansas for Medical Sciences, Little Rock, AR, USA \r\n\r\nA 10-month-old girl with low cardiac output syndrome after cardiac surgery is on a levosimendan infusion in addition to epinephrine and milrinone. Which of the following BEST describes the mechanism of action of levosimendan?\r\n”,”desc”:”EXPLANATION \r\nLevosimendan is an inodilator, first gaining European approval in the year 2000 to treat acutely decompensated chronic heart failure. Currently, it is not FDA-approved in the United States. The inotropic effects of levosimendan result from the binding of troponin C, thus stabilizing calcium-induced conformational changes and prolonging the interaction between actin and myosin filaments during systole. The resultant increase in contractility is not associated with significantly increased myocardial oxygen consumption. Levosimendan also produces vasodilation by opening ATP-sensitive potassium channels in vascular smooth muscle, which may have a cardioprotective effect by reducing excessive calcium during ischemic reperfusion injury. \r\n\r\nPatients with heart failure receiving levosimendan demonstrate improved hemodynamics and improved symptomatology without the development of drug tolerance. Since its introduction, levosimendan has been used clinically to treat cardiogenic shock, acute stress-induced cardiomyopathy, depressed right ventricular function, and pulmonary hypertension in the post-cardiac surgical and medical patient populations. The most commonly reported adverse events are hypotension, headache, atrial fibrillation, hypokalemia, and tachycardia. \r\n\r\nAlthough levosimendan is used in the pediatric population in locations outside of the United States, the literature supporting its clinical efficacy is rather limited. Lapere et al. conducted a systematic review and meta-analysis of nine randomized controlled trials involving 539 patients who were 18 years and younger that assessed the safety and efficacy of perioperative levosimendan use after cardiac surgery as compared to dobutamine, milrinone, or placebo. The authors concluded that levosimendan reduced the incidence of low cardiac output syndrome and increased cardiac index but did not have any effect on mortality, ICU length of stay (LOS), hospital LOS, duration of mechanical ventilation, serum lactate, central venous oxygen saturation, serum creatine levels, or the incidence of acute kidney injury. Pilia et al. conducted a systematic review of 48 studies, including 1,271 patients investigating the safety profile of levosimendan. Hypotension occurred in 28.9% of patients, and arrhythmias, predominantly tachycardias, occurred in 12.3% of patients. Of note, the reported dosing of levosimendan typically included a loading dose of 12 mcg\/kg over 10 to 15 minutes, followed by an infusion of 0.05- 0.2 mcg\/kg\/min. \r\n\r\nThe correct answer is A. The inotropic effects of levosimendan are mediated by increasing the sensitivity of cardiac myocytes to calcium. It also promotes vasodilation by opening ATP-sensitive potassium channels in vascular smooth muscle. Catecholamines such as epinephrine and dobutamine act predominantly by beta-receptor activation, while milrinone is a phosphodiesterase-3 inhibitor.\r\n\r\n\r\n \r\nREFERENCES \r\nNieminen MS, Fruhwald S, Heunks LM, et al. Levosimendan: current data, clinical use, and future development. Heart Lung Vessel<\/em>. 2013;5(4):227-245.\r\n\r\nPapp Z, Agostoni P, Alvarez J, et al. Levosimendan efficacy and safety: 20 years of SIMDAX in clinical use. Card Fail Rev<\/em>. 2020;6:e19. doi:10.15420\/cfr.2020.03\r\n\r\nLapere M, Rega F, Rex S. Levosimendan in pediatric cardiac anaesthesiology: A systematic review and meta-analysis. Eur J Anaesthesiol<\/em>. 2022;39(8):646-655. doi:10.1097\/EJA.0000000000001711\r\n\r\nPilia E, Silvetti S, Bohane SM, Pusceddu E, Belletti A; Safety of levosimendan in pediatric patients: an up-to-date systematic review. J Cardiothorac Vasc Anesth<\/em>. 2024;38(3):820-828. doi:10.1053\/j.jvca.2023.11.020\r\n\r\n”,”hint”:””,”answers”:{“6zedp”:{“id”:”6zedp”,”image”:””,”imageId”:””,”title”:”A.\tIncreased myocyte sensitivity to calcium “,”isCorrect”:”1″},”g555o”:{“id”:”g555o”,”image”:””,”imageId”:””,”title”:”B.\tActivation of \u03b2-1 receptors”},”attie”:{“id”:”attie”,”image”:””,”imageId”:””,”title”:”C.\tInhibition of phosphodiesterase-3\r\n\r\n”}}}}}

{“questions”:{“mlbh2”:{“id”:”mlbh2″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Anuradha Dev, MD and Marc Atwell MD – Georgetown Public Health Corporation (GPHC), Georgetown, Guyana AND Destiny F. Chau, MD – Arkansas Children\u2019s Hospital\/University of Arkansas for Medical Sciences, Little Rock, AR, USA \r\nA 10-year-old boy presents with shortness of breath and declining exercise capacity. Transthoracic echocardiography demonstrates a double chamber right ventricle. Which of the following percentages reflects the approximate number of patients with double chamber right ventricle with a concurrent ventricular septal defect? \r\n\r\n”,”desc”:”EXPLANATION \r\nDouble chamber right ventricle (DCRV) is a rare cardiac diagnosis reported in up to 2.6% of patients with congenital heart disease. It typically presents in childhood with few cases reported in adults. DCRV is described by a sub-infundibular tissue substrate within the body of the right ventricle (RV) that leads to progressive RV outflow obstruction. The obstructing tissue has been identified as hypertrophied trabecular muscle bands and\/or atypical moderator bands that divide the RV into a proximal high-pressure inlet chamber located close to the apical region of the RV and a distal low-pressure outlet chamber located near the infundibular region. There is typically an increased pressure gradient greater than 20 mmHg across the two chambers (see Figure below). \r\n\r\nIt is hypothesized that the anatomical substrate for DCRV is often present at birth. For example, congenital cardiac defects that create flow turbulence may trigger tissue hypertrophy leading to obstruction within the RV cavity. Although over 75% of DCRVs are associated with ventricular septal defect (VSD), it is also associated with tetralogy of Fallot (TOF), double outlet right ventricle, and Ebstein anomaly. The VSD of DCRV is usually small and perimembranous. Although it may be located in any location along the interventricular septum, the VSD usually connects with the proximal high-pressure inlet chamber. The resulting pathophysiology is due to shunt flow characteristics as determined by the location of the VSD in relation to the obstruction within the RV. When the VSD is distal to the obstructing muscle bundle, the resulting physiology is akin to an isolated VSD, but when the VSD connects to the RV proximal to the muscle bundle, the physiology is akin to tetralogy of Fallot. \r\n\t\r\n\r\n\r\n \r\n\r\nFigure: Two-dimensional TTE with color-flow Doppler. Parasternal short-axis view at the aortic valve level in end systole demonstrates muscular septation of the RV into a high-pressure proximal chamber and low-pressure distal subvalvular chamber. Arrows indicate RV muscular bundles causing subvalvular obstruction. AV= aortic valve, PV=pulmonic valve, TV=tricuspid valve, RA=right atrium, pRV=proximal RV, dRV=distal RV. \r\nFrom Malone RJ, Henderson ER, Wilson ZR, et al. Double-chambered right ventricle in adulthood: a case series. CASE (Phila). 2024;8(3Part A):202-209. doi:10.1016\/j.case.2023.12.012. Creative Commons Licensing 4.0. \r\n\r\nPatients with severe RVOT obstruction typically present with dyspnea on exertion and limited exercise capacity. Echocardiography is a good first-line screening tool for many cardiac defects, but the identification of DCRV may often be overlooked unless there is a high index of suspicion. Other imaging modalities such as magnetic resonance imaging or cardiac catheterization can confirm the diagnosis of DCRV. Surgery involves transatrial or transventricular resection of the obstructing muscle bundles and a VSD closure. Survival rates in the current era are excellent. However, there is the potential for a right bundle branch block or complete heart block. \r\n\r\nThe correct answer is C, over 75% of patients with DCRV also have an associated VSD.\r\n\r\n\r\n \r\nREFERENCES \r\nLoukas M, Housman B, Blaak C, Kralovic S, Tubbs RS, Anderson RH. Double-chambered right ventricle: a review. Cardiovasc Pathol<\/em>. 2013;22(6):417-423. doi:10.1016\/j.carpath.2013.03.004\r\n\r\nStout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA\/ACC guideline for the management of adults with congenital heart disease: Executive summary: A report of the American College of Cardiology\/American Heart Association task force on clinical practice guidelines [published correction appears in J Am Coll Cardiol. 2019.14;73(18):2361]. J Am Coll Cardiol<\/em>. 2019;73(12):1494-1563. doi:10.1016\/j.jacc.2018.08.1028\r\n\r\nSaid SM, Burkhart HM, Dearani JA, O’Leary PW, Ammash NM, Schaff HV. Outcomes of surgical repair of double-chambered right ventricle. Ann Thorac Surg<\/em>. 2012;93(1):197-200. doi:10.1016\/j.athoracsur.2011.08.043\r\n\r\nKahr PC, Alonso-Gonzalez R, Kempny A, et al. Long-term natural history and postoperative outcome of double-chambered right ventricle–experience from two tertiary adult congenital heart centres and review of the literature. Int J Cardiol<\/em>. 2014;174(3):662-668. doi:10.1016\/j.ijcard.2014.04.177\r\n\r\nHubail ZJ, Ramaciotti C. Spatial relationship between the ventricular septal defect and the anomalous muscle bundle in a double-chambered right ventricle. Congenit Heart Dis<\/em>. 2007; 2:421-423. \r\n\r\n\r\n\r\n”,”hint”:””,”answers”:{“842tz”:{“id”:”842tz”,”image”:””,”imageId”:””,”title”:”A.\t25%”},”c3amd”:{“id”:”c3amd”,”image”:””,”imageId”:””,”title”:”B.\t50%”},”qjgeb”:{“id”:”qjgeb”,”image”:””,”imageId”:””,”title”:”C.\t75%”,”isCorrect”:”1″}}}}}