Left ventricular outflow obstruction after Fontan procedure involving a patient with complete atrioventricular septal defects complicated by a small left ventricle.

We report a 1-year-old girl who developed ventricular outflow tract obstruction early after a Fontan operation, necessitating surgical relief using the Damus-Kaye-Stansel procedure. The patient had a complete atrioventricular septal defect complicated by a muscular ventricular septal defect (VSD) and a small left ventricle, a morphology that has not previously been reported in cases of systemic outflow tract obstruction after the Fontan procedure. Postoperative systemic outflow obstruction must be considered as a possible sequela following Fontan surgery in patients with an atrioventricular septal defect and a small left ventricle.