Aortopulmonary window in tetralogy of Fallot with absent conal septum

Aortopulmonary window is a rare conotruncal defect that is often associated with other congenital heart defects. We present a patient with a previously unreported combination of aortopulmonary window with tetralogy of Fallot with an absent conal septum.

A term, 2.4 kg newborn male infant presented at a community hospital with cyanosis unresponsive to supplemental oxygen. Transthoracic echocardiography demonstrated a conotruncal defect with a large conoventricular ventricular septal defect and an over-riding, dysplastic aortic valve. The main pulmonary artery (MPA) appeared to arise from left facing sinus of the aortic valve, with confluent yet hypoplastic right and left branch pulmonary arteries. There was no evidence of prograde flow into the MPA in systole, though there did appear to be retrograde flow in diastole from the patent ductus. The patient underwent multiple advanced imaging studies, and the diagnosis was not fully elucidated. Postmortem examination demonstrated morphology consistent with Tetralogy of Fallot with the absence of the conal septum. There were two distinct semilunar valves in fibrous continuity with an aortopulmonary window immediately cephalad to the valve.

The rare combination of defects and the patient's size made the anatomic diagnosis by conventional imaging challenging. However, retrospective review of imaging studies did demonstrate anatomic features seen by direct examination of the specimen.