Congenital abnormality in which a hole exists in the wall (septum) separating the left and right ventricles of the heart; the most commonly recognized congenital heart defect of horses.
An abnormal opening or hole in the septum between the two lower chambers or ventricles of the heart. Flow of blood is normally from left to right (left to right shunt), because of the higher pumping pressures produced by the left ventricle. If pulmonary hypertension develops, the shunt may be reversed, with blood flowing from right to left. This will result in oxygen-poor blood being delivered to the systemic side of the circulation, and the patient will appear cyanosed.
The right and left ventricles lie next to each other in the heart. The septum is the membranous wall that separates them. A ventricular septal defect is a hole in the septum.