What is a VSD?
A ventricular septal defect (VSD) is a hole in the ventricular septum, the lower wall of the heart separating the right and left ventricles (see normal heart anatomy). A VSD is a congenital heart defect, in other words, a birth defect of the heart. Congenital heart defects are the most common form of birth defects, occurring in approximately 1 in 150 children. A VSD is the most common congenital heart defect; the overall incidence is 3-4 per 1000. There are many different types of VSD’s. The most common type, termed a muscular VSD, is formed when the muscle of the wall fails to completely seal. The majority of muscular VSD’s are small ventricular septal defects and rarely of any physiologic consequence. Less common types of VSD’s include membranous, inlet and outlet types. These types of VSD's are often larger and may cause more problems for an infant or child.
Physiologically, a VSD allows for oxygenated blood (“red blood”) to pass from the left ventricle to the right ventricle, join with deoxygenated blood (“blue blood”), and return to the lungs. The overall effect of a VSD is therefore an increase in the total amount of blood that flows to the lungs. The amount is primarily determined by the size of the VSD. A large VSD allows for a significant degree of blood flow to the lungs; a small VSD often results in a negligible increase.
What causes a ventricular septal defect?
The cause of most ventricular septal defects is unknown. Some may be related to genetic disorders. Ventricular septal defects are found relatively frequently in babies with certain syndromes, for example Down syndrome, trisomy 13, and trisomy 18. Other factors that may play a role include maternal alcohol exposure or drug use. A good portion of VSD's have no explainable cause whatsoever.
What are the signs and symptoms of a VSD?
Symptoms from a ventricular septal defect are related to excess blood flow to the lungs. They are usually seen in children with large VSD’s, but may be absent in the setting of moderate size defects. Small defects rarely if ever produce symptoms. The most common symptom is rapid breathing. This may be more obvious during times of exertion, such as feeding in an infant. Other symptoms in infants include sweating with exertion, tachycardia, poor feeding due to fatigue, and poor weight gain. VSD’s may also predispose to an increased risk of lung infections such as pneumonia. Symptoms such as chest pain, palpitations, or syncope are unusual in the setting of a VSD.
How is a ventricular septal defect diagnosed?
Diagnosis of a VSD can be made in a number of different ways. Many large ventricular septal defects are identified prenatally through the use of a fetal echocardiogram. After birth, an infant or child with a VSD usually comes to attention due to the presence of a heart murmur. This simply refers to the sound that blood is making as it flows through the hole from one chamber to another. There are many other different causes of heart murmurs, including normal causes. An echocardiogram uses sound waves to visualize the intracardiac structures and is the easiest way to diagnose the size and location of a VSD. Occasionally a cardiac catheterization may be necessary to assess the lung blood pressures or the amount of shunting through a VSD. In some cases, additional heart defects may be found in association with a VSD, for example an atrial septal defect or patent ductus arteriousus.
What is the treatment for a VSD?
There is a wide spectrum of treatment options for a child with a ventricular septal defect. Between 50 to 75% of small VSD’s detected in the first few months of life close spontaneously. Even in cases where a small VSD remains open, specific therapy is rarely needed. In children with larger VSD’s who are symptomatic, medication may help. The most commonly used medicine is furosemide (Lasix), a diuretic that works by decreasing excess lung fluid caused by the extra blood flow to the lungs. Furosemide may be given anywhere from 1 to 4 times daily. Side effects are uncommon; abnormalities of electrolytes can occasionally be seen with larger doses. Another medication frequently used in the setting of a VSD is digoxin (Lanoxin). Digoxin increases calcium levels in heart cells, thereby improving overall heart function.
VSD surgery is occasionally necessary, especially in the setting of a large or moderate size VSD. Indications for surgery in infancy include symptoms unresponsive to medication, elevated blood pressure in the lungs, and significant dilation of the heart due to excess blood flow. Usually the need for surgery in an infant becomes clear by 6-12 months of age, and often much earlier. Less common indications for surgery are infection of heart tissue due to the VSD, and damage to the aortic valve secondary to the VSD. VSD surgery usually involves the placement of a patch over the hole to close it. The risk of surgery for a VSD in this day and age is relatively low. The vast majority of children do very well with no significant long term problems.
What are the outcomes for a child with a ventricular septal defect?
In general, the prognosis for a child with a ventricular septal defect is very good. Even those children who go on to require surgery generally do well long-term. In most cases only a single surgery is necessary. The vast majority of children are cleared for full activity, including competitive athletics.
Up until recently, patients with any form of heart defect, including a VSD, were recommended to use antibiotics (SBE prophylaxis) prior to dental work or surgery to minimize the risk of heart-related infection. However, in May 2007 the American Heart Association changed this recommendation such that now most patients with congenital heart disease, including those with a VSD, no longer require this precaution.
In summary, although a ventricular septal defect can cause alarm and concern in families, fortunately in almost all cases it is a very treatable condition.