Purpose or Case Report: Single ventricle heart defects (SVHD) refer to a rare and diverse group of severe congenital cardiac abnormalities in which the systemic and pulmonary venous return enter a functionally single ventricular chamber. This condition is typically caused by underdevelopment of an atrioventricular valve and/or a ventricular chamber, leading to a range of complex congenital heart defects. With an incidence of approximately 3 to 5 per 10,000 live births, newborns with SVHD are critically ill, and without medical intervention, the condition is fatal. Advancements in surgical techniques, namely staged palliation and orthotopic heart transplantation, have enabled more patients with SVHD to survive into adulthood. However, despite these improvements, the perinatal period remains tenuous.

We present a five-week-old male infant born at 38 weeks of gestation with a functional SVHD in the form of severe subaortic stenosis, arcade-like mitral valve, left ventricular dilation and dysfunction, and restrictive atrial septum. He received multiple surgical interventions, including atrial septal stenting with pulmonary artery banding and stage I reconstruction with a right Blalock-Thomas-Taussig shunt. Postoperative course was complicated by delayed sternal closure, cardiac arrest, right hemidiaphragm plication, and progressive heart failure. At five weeks, CT angiography showed a functional single ventricle status post Damus-Kaye-Stansel anastomosis, hypoperfusion of the left ventricle myocardium, and pneumoperitoneum. Exploratory laparotomy with segmental bowel resection revealed perforated acute appendicitis and mucosal ulceration of the cecum. Following the procedure, he developed acute hypoxemia and bradycardia. Life-sustaining support was withdrawn. Postmortem examination of the heart was notable for severe aortic stenosis with subaortic obstruction, stenotic mitral valve with arcade-like fibrous plaques, and biventricular hypertrophy. Histopathology of the left ventricle showed significant subendocardial fibrosis without areas of myocyte injury.

Due to the complexities involved in its management, SVHD demands special attention from radiologists. While advancements in medical and surgical care have improved outcomes, ongoing progress depends on a deeper understanding of the factors contributing to ventricular dysfunction and heart failure in this vulnerable population.
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