Atrioventricular septal defect with communication at the atrial level only. The disease is MONDO_0020437 (atrial septal defect, ostium primum type). Also known as: ASD ostium primum type, ASD, ostium primum type, PAVC, PAVSD, atrial septal defect ostium primum, atrioventricular defect with atrial shunting only, incomplete atrioventricular canal defect with isolated atrial component, incomplete atrioventricular septal defect with isolated atrial component.