Partial atrioventricular septal defect (ASD Type I, Ostium primum defect)

Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect (VSD). These defects result from maldevelopment of the endocardial cushions. Patients with no VSD component or a small VSD and good AV valve function may be asymptomatic. If there is a large VSD component or significant AV valve regurgitation, patients often have signs of heart failure, including dyspnea with feeding, poor growth, tachypnea, and diaphoresis. Heart murmurs, tachypnea, tachycardia, and hepatomegaly are common. Diagnosis is by echocardiography. Treatment is surgical repair for all but the smallest defects.