The atrioventricular septum is a septum of the heart between the right atrium (RA) and the left ventricle (LV).

[1][2] Although the name "atrioventricular septum" implies any septum between an atrium and a ventricle, in practice the divisions from RA to RV and from LA to LV are mediated by valves, not by septa.

[5] This septum divides the atrioventricular canal.

[6] In some cases, defects can be identified with an echocardiogram.

[7] Incomplete formation of the endocardial cushions can lead to atrioventricular septal defects, such as an ostium primum defect.