ventricular septal defect

(VSD) a defect of the heart, usually congenital but occasionally acquired due to damage following myocardial infarction, in which there is a hole in the partition (septum) separating the two ventricles (see septal defect). In 25% of patients there are other defects present. 50% of VSDs close spontaneously. If the hole is large, blood is diverted to the lungs at a greater pressure than usual and pulmonary hypertension can occur, which becomes irreversible and progressive (Eisenmenger reaction). Early surgical intervention can prevent this.