A hole in the partition (septum) between the left and right halves of the heart. This abnormal communication is usually congenital due to an abnormality of heart development in the fetus, but can occasionally occur as a complication of myocardial infarction. It may be found between the two atria (see atrial septal defect) or between the ventricles (see ventricular septal defect). A septal defect permits abnormal circulation of blood from the left side of the heart, where pressures are higher, to the right. This abnormal circulation is called a shunt and results in excessive blood flow through the lungs. Pulmonary hypertension develops and heart failure may occur with large shunts. A heart murmur is normally present. Large defects are closed surgically or by using percutaneous catheter techniques (see atrial septal defect) but small defects do not require treatment.
Subjects: Medicine and Health.