This defect is very similar to atrial septal defects. In this case, the hole or "defect" is in the heart muscle forming a wall between the ventricles (the intraventricular "septum"). As in the case of the ASD, the heart can dilate, the muscle can become weak, and the pressures in the pulmonary arteries can increase (pulmonary hypertension) due to the increase in blood flow. If the defect is closed, these consequences can be avoided.

Like ASD’s, the size and therefore the clinical course of these defects is quite variable. Some remain large, while others become smaller over time. It is not unusual for small-to-medium sized VSD’s to eventually close spontaneously. Many, but not all that remain will require surgery.

If a substantial size defect is not corrected, then the pressures in the pulmonary arteries may become very high and induce changes in the arteries themselves such that even closure of the defect will no longer improve the patient. In this case, the pressures in the right side of the heart are high enough that blood may begin to flow from the right to the left side of the heart. This situation is called "Eisenmenger’s syndrome", a condition which may result from several similar abnormalites.
©COPY:1997 HeartPoint    Updated November 1997