An abnormal communication between the ascending aorta and main or branch pulmonary artery results in severe left-to-right shunting. The degree of pulmonary overcirculation, pulmonary hypertensive vascular changes, congestive heart failure, and failure to thrive depend on associated anomalies and the size of the defect, which is often large enough to allow equalization of pulmonary and aortic pressures. Associated malformations are present in 50 to 60 percent of cases and include interrupted aortic arch, tetralogy of Fallot and anomalous origin of the right pulmonary or coronary artery.
Surgical closure of large defects is indicated at the time of diagnosis in order to avoid early development of fixed pulmonary hypertension. Patch repair using a transaortic, transpulmonary, or “sandwich” approach has excellent outcomes. Small defects can be ligated or approached by percutaneous techniques.
Aortopulmonary (AP) window is a rare congenital anomaly, accounting for 0.2 to 0.5 percent of all congenital heart defects.1 It consists of a communication between the aorta and the pulmonary artery or its branches. Although closely related to AP window, pulmonary artery origin from the ascending aorta (also erroneously termed “hemitruncus”) is classified as a separate defect.
AP window was first described by Elliotson in 1830 in an autopsy study.2 In 1948, Robert Gross successfully ligated an AP window in a patient undergoing a thoracotomy for closure of a patent ductus arteriosus (PDA).3 In 1957, Cooley and associates described the first successful repair of AP window using cardiopulmonary bypass.4
The pathophysiology of AP window is similar to that of a ventricular septal defect, PDA, or truncus arteriosus consisting of a left-to-right shunt. The amount of left-to-right shunting is related to the size of the defect and the pulmonary vascular resistance. Patients with small defects can be completely asymptomatic. With large defects, and as the pulmonary vascular resistance decreases in the first weeks of life, symptoms of congestive heart failure develop rapidly, and irreversible pulmonary vascular disease can occur as early as during the first 12 months of life. If untreated, 40 percent of patients will die of intractable heart failure during the first year of life, and survivors will succumb to the sequelae of congestive heart failure and severe irreversible pulmonary vascular disease during childhood (Fig. 67-1).5
Embryology and Morphology