Heart Septal Defects, Atrial

**Definition:** Developmental abnormalities in any portion of the ATRIAL SEPTUM resulting in abnormal communications between the two upper chambers of the heart. Classification of atrial septal defects is based on location of the communication and types of incomplete fusion of atrial septa with the ENDOCARDIAL CUSHIONS in the fetal heart. They include ostium primum, ostium secundum, sinus venosus, and coronary sinus defects.

**Tree numbers:** - C14.240.400.560.375 - C14.280.400.560.375 - C16.131.240.400.560.375

**Synonyms:** - Atrial Septal Defect - Atrial Septal Defects