Ventricular Septal Defect

Ventricular septal defect (VSD), which is sometimes called a “hole in the heart,” is one of the most common of the congenital heart defects. VSDs occur in about four out of every 1,000 live births and account for up to 40 percent of all congenital heart problems. VSD is a common component of some of the more complex types of congenital heart disease (such as tetralogy of Fallot), but most of the time a VSD is an isolated heart defect.

The severity of VSDs can vary widely from person to person. In many, it is a relatively minor problem that requires only observation over time. But in others, a VSD a severe problem that needs to be corrected in early childhood. 

In most cases, VSDs are detected in the first weeks of life. However, sometimes a VSD may not be diagnosed until adulthood when a relatively moderate VSD finally begins to produce consequences. In addition, while uncommon, a person born with a normal heart can develop a VSD in adulthood, as a result of acquired heart disease, or as a complication of a cardiac surgical procedure.

What Is a VSD?

Normally, the heart’s two main pumping chambers, the right, and left ventricles are separated from one another by a muscular wall called the ventricular septum. A ventricular septal defect is an abnormal opening in the ventricular septum, essentially a hole. This opening allows blood to flow directly from one ventricle into the other.

When a cardiac abnormality allows blood to flow between the left side of the heart and the right side of the heart, this is referred to as a “shunt.” With a VSD, the abnormal shunting of blood from the left ventricle into the right ventricle can cause a range of cardiovascular problems.

Why Are VSDs Important?

An opening in the ventricular septum allows blood to shunt between the right and left ventricles. Because the pressure in the left ventricle is higher than in the right ventricle, a VSD will produce a “left-to-right shunt,” that is, a shunt in which some of the blood in the left ventricle flows into the right ventricle. 

A large VSD will produce a large left-to-right shunt, and as a consequence, the right ventricle and the pulmonary circulation (the blood being pumped into the blood vessels supplying the lungs) become overloaded with blood, and the left ventricle is “overloaded” with extra work. 

People with a large VSD typically develop severe symptoms of pulmonary congestion and/or heart failure very quickly, so treatment (medical, and quite possibly surgical), is mandatory.

In someone with moderate-sized VSDs, symptoms may develop quite gradually, often over several years. The chronic overload of the pulmonary circulation in these people may eventually produce fixed (permanent) pulmonary hypertension. So it is important to carefully monitor people with moderate VSDs over time and to treat them aggressively if any signs of pulmonary hypertension develop. 

Small VSDs may produce little or no shunting, so they are unlikely to produce pulmonary congestion or heart failure. Furthermore, in infants, small VSDs are likely to close completely as the child grows.

In addition, a VSD of any size produces at least some turbulence within the heart, which somewhat increases the risk for infectious endocarditis.

What Causes VSDs?

The large majority of VSDs are congenital. They result from a failure of the ventricular septum to complete its normal formation in the fetus. 

Numerous genetic abnormalities have been identified that increase the risk of VSD. Some of these abnormalities are associated with well-defined genetic conditions such as Down syndrome and DiGeorge syndrome.

More often, VSD appears to be related to sporadic gene mutations that are not inherited from the parents. Usually, a VSD in a particular person cannot be attributed to any specific genetic abnormality.

VSDs in Infants and Children

The large majority of people with VSDs are diagnosed during infancy or early childhood when a normally-developed infant or child either begins to have symptoms, or a heart murmur is detected.

Most kids with VSDs are normally-developed at birth. This is because the presence of a VSD has no impact on the growing fetus. Because the pressures within the right and left ventricles are nearly equal in utero, there is little or no shunting across a VSD prior to birth.

Immediately upon birth, however, as the infant begins to breathe and the right-sided heart circulation is directed into the low-resistance pulmonary blood vessels, the pressure within the right side of the heart drops. If a VSD is present, left to right shunting begins, and if the VSD is large enough, symptoms appear.

large ventricular septal defect in kids
Illustration by JR Bee, Verywell

Symptoms of VSD in Kids

The symptoms produced by a VSD in infants and children are related to the size of the VSD, and consequently, to the amount of blood that is being shunted across the VSD from the left to the right ventricle.

A large VSD causes a lot of shunting and overloads the pulmonary circulation. This causes the newborn infant to develop problems including tachypnea (rapid breathing), sweating, poor feeding, and a general failure to thrive. The baby may also have an enlarged liver (from blood engorgement), a rapid heart rate, and may grunt with each breath (indicating increased labor of breathing).

Small VSDs, on the other hand, most often produce no symptoms at all. However, with a small VSD, a cardiac murmur usually becomes obvious within the first week or so of life. In fact, because shunting across a small VSD causes more blood turbulence than with a large one, the heart murmur of a VSD is often louder with a small VSD.

VSDs that are of moderate size will produce symptoms that are somewhere in between these two extremes. 

Evaluating VSD in Kids

If a doctor suspects a VSD may be present, either because of symptoms or because a heart murmur is detected, the evaluation is usually pretty straightforward. An ECG may show a rapid heart rate and signs of ventricular hypertrophy (thickened heart muscle). A chest X-ray may show increased pulmonary vascular blood flow and signs of enlargement of the right-sided heart chambers.

But the echocardiogram is the test that usually reveals a VSD definitively, and, in addition, allows the doctor to estimate the size of the left-to-right shunt.

Treating VSD in Kids

The optimal treatment of a VSD depends on its size, and the degree of shunting it is producing. 

In kids with small VSDs that are producing a small shunt, surgical repair is not recommended. A substantial proportion of these small VSDs will close spontaneously within the first 12 months of life, and up to 60 percent will close within a few years.

If a small VSD persists but continues to produce no symptoms, surgical treatment is still not recommended, since the chances that a small VSD will ever lead to cardiovascular problems are quite small. Kids with small VSDs and no symptoms should be periodically evaluated by a cardiologist. If they ever should develop symptoms, they need a full cardiac evaluation to look for other potential causes.

Newborn babies with large or moderate VSDs need careful monitoring and observation during the first weeks of life, since heart failure is most likely to develop during this early period. The baby should be observed closely signs or symptoms of heart failure (particularly tachypnea, failure to gain weight, or sweating while feeding).

If the child develops signs of heart failure, medical treatment should be initiated, including diuretic therapy, nutritional supplements to support normal growth, and vaccinations to lower the risk of infections such as the flu and respiratory syncytial virus. If the child responds to this treatment, and symptoms resolve and normal growth resumes, periodic echocardiograms should still be obtained to monitor the size of the shunt and to look for evidence of pulmonary hypertension. 

Surgical closure of the VSD should be performed if the child fails to respond to medical therapy, or if it looks like pulmonary hypertension is developing.

Surgical repair of a VSD is usually done with open-heart surgery, using a patch to close the septal defect. While a catheter-based “minimally invasive” procedure for closing VSDs has been developed, this is a technically difficult procedure with a relatively high complication rate. Transcatheter VSD closure is generally reserved for kids who are not candidates for open surgical repair.

Children born with VSDs, whether or not they require surgical treatment, need lifelong vaccinations to protect them from infections, periodic medical evaluations, and ongoing medical advice regarding participation in sports. Current guidelines do not recommend antibiotic prophylaxis for endocarditis in people with a VSD unless a surgical patch has been used.

VSDs in Adults

Isolated VSDs in adults almost always represent congenital VSDs that have not spontaneously closed. Rarely, VSDs can also occur in adults as a complication of cardiac surgery, or as a consequence of a heart attack.

An acute VSD caused by a heart attack is referred to as septal rupture. Septal rupture, which is thankfully very uncommon, is generally caused by a very large heart attack that has produced substantial cardiac muscle damage. It is manifested by sudden signs and symptoms of heart failure and carries a high risk of death.

The large majority of VSDs in adults, however, are congenital VSDs.

Symptoms of VSD in Adults

Most VSDs that persist into adulthood are small or moderate-sized VSDs that either has caused no symptoms during childhood, or that initially caused heart failure symptoms (tachypnea, dyspnea, fatigue, and/or growth problems), but were stabilized with medical treatment.

In many of these cases, as the child grows, even persistent VSDs become smaller, and consequently, the degree of cardiac shunting diminishes—and symptoms disappear.

Sometimes, however, uncorrected VSDs cause enough shunting to gradually produce permanent pulmonary hypertension. If pulmonary hypertension occurs in a person with a VSD, the elevated pressure within the right side of the heart may cause the shunting across the VSD to actually reverse. That is, blood is now being shunted from the right ventricle to the left ventricle.

The condition in which shunting reverses (from left-to-right shunting to right-to-left shunting) is called Eisenmenger syndrome. Eisenmenger syndrome is often a pretty dire situation. It often produces cyanosis (bluish skin discoloration caused by low blood oxygen levels), extreme fatigue and dyspnea, hemoptysis (coughing up blood), headaches, syncope, and abdominal swelling. It is associated with early mortality. Once this condition develops, surgically closing the VSD will not only be ineffective but would be extraordinarily risky.

Avoiding pulmonary hypertension and Eisenmenger syndrome is the main goal in chronically monitoring people with VSDs.

Evaluating VSD in Adults

As in kids, performing an ECG, a chest X-ray, and a thorough echocardiogram is usually sufficient to detect a VSD, and determine its size and the degree of shunting it is producing.

In addition, stress testing is often used in adults with a VSD to gain an objective measure of whether the defect is causing substantial physical limitations. Adults with VSD will often gradually and unconsciously reduce their physical activity, and thus will report no exercise limitations to their doctor. The stress test can give the doctor a more accurate appraisal of cardiovascular fitness and can help in forming recommendations for or against surgical repair.

If surgery is being considered, cardiac catheterization will often be done to assess the status of the coronary arteries, and to determine the extent of any existing fixed pulmonary hypertension. 

Treating VSD in Adults

As noted already, surgical repair of VSDs in children is generally performed only when heart failure has occurred which is not manageable with medical treatment. This relative reluctance to operate on kids is justifiable, because VSDs in kids often close spontaneously, or at least become substantially smaller as time goes by.

The situation is different in adults. In a fully grown person, there is no chance that the VSD itself will become smaller over time.

Because the VSD will not become smaller, surgical VSD repair is currently recommended for any fully-grown person whose VSD is producing symptoms, or in whom the clinical evaluation (chiefly, the echocardiogram) shows signs that the left ventricle is being overworked as a result of left-to-right shunting—a condition called “ventricular overload.” 

However, because the surgical repair of a VSD is no longer safe or effective if substantial pulmonary hypertension has already occurred, surgery must be done before pulmonary hypertension develops. This is why lifelong monitoring is necessary for anyone born with a VSD.

With modern techniques, surgical repair of a VSD can be performed in adults who are otherwise healthy with a very low risk of surgical or postoperative death. 

VSD repair does expose people to certain complications, however, some of which may occur long after surgery is performed. These include residual VSD (incomplete VSD repair), tricuspid regurgitation (leaky tricuspid valve caused by surgical damage to the valve mechanism), and cardiac arrhythmias.

Late cardiac arrhythmias after surgical repair may include PVCs, ventricular tachycardia, atrial fibrillation, and (especially if the VSD is located high in the ventricular septum, near the AV node and His bundle), heart block.

As is the case with children with VSD, antibiotic prophylaxis is not recommended for adults with a VSD, unless a surgical patch has been placed in the heart.

Pregnancy and VSD

Women with small or surgically repaired VSDs can go through pregnancy without additional risk to themselves or their babies.

Women who have VSDs with relatively large shunts, or who have heart failure or pulmonary hypertension caused by a VSD, have a substantially elevated risk associated with pregnancy. Doctors urge these women to avoid pregnancy altogether.

A Word From Verywell

A ventricular septal defect—an opening in the septum of the heart—is a relatively common congenital heart defect. Because a VSD in a newborn will usually become smaller over time (or, in many cases, will completely close), surgery in kids with VSD is avoided unless the VSD is severe. In adults with large or moderate-sized VSDs, the VSD will not shrink and become less severe over time, and surgical repair is usually recommended.

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By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.