A Direct Connection Between the Aorta and Pulmonary Artery Introduction Aortopulmonary Window — AP Window or APW — is a rare congenital cardiac defect in which there is an abnormal opening between the ascending aorta and the pulmonary artery. Importantly, the aorta and pulmonary artery are otherwise separate vessels with separate semilunar valves. This distinguishes … Continue reading Aortopulmonary Window