- A congenital defect characterized by the failure of the ductus arteriosus to close soon after birth. As a consequence, blood from the aorta mixes with blood from the pulmonary artery. If untreated, it may lead to congestive heart failure.
- A congenital heart defect characterized by the persistent opening of fetal ductus arteriosus that connects the pulmonary artery to the descending aorta (aorta, descending) allowing unoxygenated blood to bypass the lung and flow to the placenta. Normally, the ductus is closed shortly after birth.
- Abnormal persistence of an open lumen in the ductus arteriosus after birth, the direction of flow being from the aorta to the pulmonary artery, resulting in recirculation of arterial blood through the lungs.