An opening exists between the two lower chambers of the heart. Some blood that has returned from the lungs and has been pumped into the left ventricle flows to the right ventricle through the hole instead of being pumped into the aorta. The heart, which has to pump extra blood, is over-worked and may enlarge.
If the opening is small, it doesn't strain the heart. In that case, the only abnormal finding is a loud murmur. But if the opening is large, open-heart surgery is recommended to close the hole and prevent serious problems. Some babies with a large ventricular septal defect don't grow normally and may become undernourished. Babies with VSD may develop severe symptoms or high blood pressure in their lungs. Repairing a ventricular septal defect with surgery usually restores the blood circulation to normal. The long-term outlook is good, but long-term follow-up is required.
People with a ventricular septal defect are at risk for getting an infection of the heart's walls or valves (endocarditis). To help prevent this, they'll need to take antibiotics before certain dental and surgical procedures. After a VSD has been successfully fixed with surgery, antibiotics should no longer be needed.