Massively Hypertrophied Right-Sided Heart with Hypoplastic Left-Sided Heart in a Neonate (A Rare Type of Hypertrophic Cardiomyopathy)

Described herein is a newborn boy with likely right-sided hypertrophic cardiomyopathy (HC), who survived for 18 hours after birth. At necropsy, he had a severely thickened right ventricular free wall, ventricular septum, right atrial wall and a hypoplastic left-sided heart. There was a large fossa ovale type atrial septal defect and also a patent ductus arteriosus. During peak systole, the right ventricular outflow tract was obstructed, and its contents were pushed into the thick-walled right atrium, then rapidly into the thin-walled left atrium via a large fossa ovale atrial septal defect. The contents were then pushed into the thin-walled left ventricle and finally into the small ascending aorta and into the lungs via a large patent ductus arteriosus. We were unable to find a similar published case. (c) 2022 Elsevier Inc. All rights reserved. (Am J Cardiol 2023;190:126-130)