A 10-year-old female patient presented with dyspnea during play with peers. She had been diagnosed with a large perimembranous ventricular septal defect neonatally but had since been lost to follow-up. On physical examination, she was fully saturated, with a 4/6 systolic murmur along the left sternal border. Transthoracic echocardiography identified a restrictive perimembranous ventricular septal defect but with bidirectional flow and peak gradient of 110 mm Hg out the right ventricular outflow tract. Catheterization revealed suprasystemic pressures in the right ventricular apex with a peak gradient of 107 mm Hg between the right ventricle and the pulmonary artery. On angiography (A,Online Video 1), aneurysmal septal tissue (black arrow) could be seen oscillating within the right ventricular outflow tract in addition to mild infundibular hypertrophy. Pre-operative transesophageal echocardiography (B, white arrow denoting aneurysmal tissue, black arrow denoting pulmonary valve; C, black arrow denoting aneurysmal tissue, white arrow denoting perimembranous septal defect; Online Videos 2 and 3) and ultimately surgical resection (D, black arrow denoting aneurysmal tricuspid tissue) confirmed the diagnosis of subpulmonic obstruction by aneurysmal tricuspid valve tissue and infundibular hypertrophy.