A ventricular septal defect (VSD) is an opening that exists between the two lower chambers of the heart. Some of the blood returning from the lungs and into the left ventricle flows to the right ventricle through the hole instead of being pumped into the aorta. Because the heart has to pump extra blood and is overworked, it may enlarge.
If the opening is small, very little extra blood is pumped to the lungs, and the left heart is nearly normal in size. In that case, the only abnormal finding is a loud murmur typically heard in a VSD. These small holes are usually left alone unless they cause other problems with the heart due to their location (some holes are close to the aortic valve and may suck the leaflet into the hole causing progressive leakiness of the aortic valve).
Heart with Ventricular Septal Defect
If the hole is large, a lot of extra blood is pumped to the lungs and back to the left ventricle so that the left ventricle is enlarged. Also, with larger holes, the pressures in the left and right ventricles become equal. In infants and children with large holes, symptoms develop such as breathing quickly, sweating with feeds, poor growth or exercise intolerance. Medications may help with these symptoms and give the time for the hole to close or get smaller on its own (50% of VSDs close spontaneously), but with a large hole, closure is usually recommended. If large holes are untreated, the large amount of extra blood and the elevated pressures in the lungs causes injury to the small arteries going to the lungs known as pulmonary vascular disease. Sometimes this is reversible, but after many years, it becomes irreversible and causes Eisenmenger syndrome.
Small defects may cause no symptoms, and large defects may cause symptoms of poor growth, breathing difficulty, sweating and problems with exercise. Small and large defects cause abnormal murmurs which can be detected on physical examination. However, in newborn infants, the pressure in both the right and left ventricle may be nearly equal, so frequently the abnormal murmur (and symptoms) does not appear right at birth. It may take a few weeks for the symptoms (if the defect is large) and the abnormal murmur to occur.
The diagnosis is confirmed with an echocardiogram.
Currently, open-heart surgery is the recommended method to close most holes and prevent serious problems. The VSD is usually closed with a patch of synthetic material or sometimes by stitches alone. Some holes may be closed with occlusion devices in the cardiac catheterization laboratory. Sometimes, neither open-heart surgery nor closure during cardiac catheterization are possible, and a pulmonary artery band (PA) band is placed. This is tied around the pulmonary artery to limit the amount of blood that can go to the lungs. Repairing a ventricular septal defect with surgery usually restores the blood circulation to normal.
The risks of surgery include a small chance that the electrical system of the heart is injured, and a pacemaker will be needed. Special risks of open-heart surgery are the need for cardiopulmonary bypass. Also, it is not uncommon to have a small amount of blood leaking around the edges of the patch used to close the VSD.
If left untreated, the long-term outlook for very small VSDs is good, though there is always the risk of infection (endocarditis) which may lead to complications. For larger VSDs, the enlargement of the heart may lead to problems with heart function or rhythm abnormalities. With very large VSDs, Eisenmenger syndrome may develop which results in a shortened lifespan and limitations in exercise and lifestyle.
The long-term outlook for VSDs closed in childhood is good, but long-term follow up may be needed. Prophylaxis for bacterial endocarditis may still be needed unless no residual shunts are present. Your pediatric cardiologist should be able to let you know if this is necessary.