<p>Interventricular septal hematoma is a rare complication of pediatric cardiac surgery, usually in the context of ventricular septal defect closure.&nbsp;We present intraoperative echocardiography of a large interventricular septal hematoma secondary to the placement of a left ventricular assist device (VAD) in an infant who required conversion to biventricular support with bi-atrial cannulation. As the patient later died of neurologic complications, we present correlation with pathologic findings.</p>