I51: Complications and ill-defined descriptions of heart disease

I51.0: Cardiac septal defect, acquired

The heart pumps blood through the body. Inside the heart are 4 chambers. There are 2 heart atria and 2 ventricles. Both heart atria and both ventricles are separated from each other by a partition. Between the atria and the ventricles there is a separating wall made of heart muscle. In your case, a hole has formed in the wall between the ventricles or between the atria.