Dissecting ventricular septal hematoma (DVSH) rarely occurs after repair of a ventricular septal defect (VSD) but can lead to serious complications such as septal rupture, myocardial rupture, cardiogenic shock, heart block, outflow obstruction, cardiac tamponade, abscess transformation, and death. This paper describes the diagnosis and management of acute, severe, left ventricular outflow tract obstruction caused by the development of a DVSH after VSD repair.