Ventricular septal defect: Ventricular septal defect is a defect in the wall between the two lower chambers of the heart – left and right ventricles. As a result, oxygenated blood from the left ventricle which has a higher pressure enters the right ventricle. This in turn gets pumped to the right ventricle, increasing the pulmonary blood flow. The extra blood then returns from the left ventricle to the left atrium and back to the left ventricle. This vicious cycle increases the work of the left ventricle, which can fail in early infancy.
What symptoms are noted in children with ventricular septal defect?
Children with small ventricular defects do not have any symptoms. Since the mixing of blood is only in small amount, it hardly affects the circulation. But they get detected when the child is seen by a doctor for some other reason. Small defects paradoxically produce a loud heart murmur so that the doctor can detect it very easily. More so when the baby is having fever which increases the speed of blood circulation. Small defects produce loud murmur because there is a large pressure difference between the left and right ventricles. The blood jet passes across the defect at high velocity and produces a loud murmur.
When there is a large defect, the large quantity of blood mixing between the two ventricles increases the workload of the heart very much. This leads to heart failure in early childhood. In very small infants it manifests as breathlessness during feeding, poor weight gain and undue head sweating. Lower parts of chest can be seen retracting during breathing due to the high workload of breathing when the lungs are heavy with fluid collection in heart failure.
As time passes, in those large defects, the blood pressure in the lungs go up due to large excess of flow. A stage is reached when the blood pressure in the lungs rises above that in the general circulation. This leads to right ventricular pressure rising above the left ventricular pressure. Hence there is a reversal of flow across the defect (right to left shunt in contrast to the initial left to right shunt). Right to left shunt causes poorly oxygenated blood to reach the left ventricle and the general circulation. Child develops bluish discoloration of lips and nails (cyanosis). This situation is called Eisenmenger Syndrome.
What is the treatment for ventricular septal defect?
Small defects seldom produce any harm and are generally left alone. Only precaution they need is prompt treatment of infections to avoid a very rare complication of infective endocarditis. They need follow up to see whether they are developing leakage of a nearby valve (aortic valve).
Large defects produce symptoms and have a risk of developing complications. Hence they have to be closed either by open surgery or by devices. In case of large defects, the earlier the procedure is done the better. This will prevent damage to the blood vessels of the lungs which would otherwise occur in the long run due to excessive blood flow through them. All defects are not suitable for device closure as some defects may be close to vital structures within the heart which can be damaged by the constant pressure by the side flange of the device. Some defects may be located in such a way that a device may not stay and get dislodged. So a careful echocardiographic study (ultrasound study of the heart) is has to be done prior to deciding whether surgery or device closure is suitable. Surgery is done in the operating room while device closure is done in the cardiac catheterization laboratory.