A ventricular septal defect (VSD) is a hole between the right and left pumping chambers of the heart.

The heart has four chambers: a right and left upper chamber called an atrium and a right and left lower chamber called a ventricle.

In the normal heart, the right and left chambers are separated from each other by a wall called a septum. The right atrium is separated from the left atrium by the atrial septum. The right ventricle is separated from the left ventricle by the ventricular septum.

It is normal for all infants to be born with a small hole between the two atria which usually closes within the first few weeks of life.

Normally there is no hole between the two ventricles, but some infants are born with these holes called ventricular septal defects.

Ventricular septal defects are among the most common congenital heart defects, occurring in 0.1 to 0.4% of all live births. Ventricular septal defects are one of the most common reasons for infants to see a cardiologist (a doctor who treats the heart).

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Description of Ventricular Septal Defects

Ventricular septal defects occur in many locations and sizes. The ventricular septum is made up of different types of tissue, with one part composed of muscle and another part made of thinner tissue. The location and size of the hole within the septum will determine in part how to treat the ventricular septal defect.

Small ventricular septal defects rarely cause problems. A doctor usually discovers these holes by noticing an extra heart sound called a murmur on a routine physical exam.

Most of these small holes will close on their own, particularly if they are in the muscular part of the septum. Even if these holes do not close, they will rarely cause any health problems.

However, these holes can sometimes be connected to the development of other heart issues. If the small ventricular septal defect does not close, the child should continue to be seen by a cardiologist for occasional checkups.

Large ventricular septal defects cause symptoms, often developing gradually in the first few months of life. Before birth, the pressure on the right side of the heart is equal to pressure on the left side of the heart.

As soon as a baby takes their first breath, the pressure in the lungs and the right side of the heart starts to decrease. This process is slow and usually takes about 2-4 weeks for the pressure in the lungs to reach normal level.

Therefore, in the first few weeks of life, babies with large ventricular septal defects may show no symptoms. As the pressure in the right side of the heart decreases, more blood will flow to the lungs because this is the path of least resistance (from the left ventricle through the ventricular septal defect to the right ventricle and into the lungs). This will gradually lead to symptoms of congestive heart failure and must be treated.

Medium or moderate ventricular septal defects are more challenging to predict. Sometimes babies born with moderate ventricular septal defects will have problems with congestive heart failure like babies with large ventricular septal defects. Others will have no problems and will need to be watched.

Ventricular septal defects never get bigger and sometimes get smaller or close completely. When a baby is diagnosed with a ventricular septal defect, most cardiologists will not recommend immediate surgery. They will closely watch the baby and try to treat symptoms of congestive heart failure with medicine to allow time to decide if the defect will get smaller or close on its own.

Signs and Symptoms

Ventricular septal defects have a very characteristic murmur, to the point where a cardiologist may be able to pinpoint the location and estimate the size of a ventricular septal defect just by how it sounds.

A murmur is often not heard at birth. However, with the pressure changes in the lungs, the increased flow across the hole between the pumping chambers can be heard as a murmur.

A smaller hole may make a louder noise than a large hole, and the murmur may get louder as the ventricular septal defect closes. Think of a garden hose. If the water flows freely, it makes a soft sound. If you make the outlet of the hose smaller with your finger, the noise will get louder. It is important to remember a loud murmur does not mean a large hole.

Babies who do have moderate or large ventricular septal defects with excessive blood flow to the lungs will have signs of congestive heart failure including fast breathing and trouble feeding. The most important symptom to watch will be the baby's growth. If the baby does show significant signs of congestive heart failure, the ventricular septal defect may need to be surgically closed.

Babies who have significant congestive heart failure will have failure to thrive and will have difficulty with normal weight gain in the first few months of life.

Babies with some extra flow to the lungs may grow well because their ability to feed is unaffected. They may still have some subtle signs of congestive heart failure such as continuous fast breathing.

Diagnosis of Ventricular Septal Defects

Most ventricular septal defects can be diagnosed on physical exam, due to their murmur.

This heart defect may also be diagnosed on fetal echocardiograms. It is one of the cardiac defects that may be found on screening ultrasounds. Early diagnosis of the defect allows for planning after birth.

Echocardiograms can give detailed information of the anatomy of the various cardiac structures affected in this congenital defect. They also give important information about the function of the heart.

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The heart can sometimes be seen or felt to be beating hard because of the extra work it is performing. Babies can be continuously breathing fast or hard and have a fast heart rate.

An electrocardiogram can help determine the sizes of the chambers to see if there is strain on the heart due to the ventricular septal defect. The electrocardiogram can be normal at birth and change with time as congestive heart failure worsens and the heart becomes larger. It can also suggest if there are other heart defects associated with the ventricular septal defect. 

A chest X-ray can help follow the progression of congestive heart failure by looking at the size of the heart and the amount of blood flow to the lungs. This may be normal at birth and change with time. 

Most small ventricular septal defects that are suspected based on a heart murmur will not require an echocardiogram as they tend to close. Infants with moderate or large ventricular septal defects will need to have at least one echocardiogram to provide the cardiologist with a complete picture of the defect. The echocardiogram will also look at all structures of the heart to assess for any associated issues.

In some children with ventricular septal defects, a cardiac catheterization is needed. This can help the cardiologist determine how much blood flow is going out to the lungs. This can be useful in figuring out the need for surgery in children who have had subtle signs of congestive heart failure but who do not have clear-cut evidence of the need for surgical repair. Cardiac catheterization may also be needed if there is a late diagnosis of ventricular septal defect (after the first few years of life) with concern for abnormally elevated pressures in the lungs. In this case, catheterization is important to help decide if the ventricular septal defect will be safe to close.

Treatment for Ventricular Septal Defects

For most small or moderate-sized ventricular septal defects, observation is needed, with regular checkups with the cardiologist. These are typically more frequent in babies while they are being monitored for development of symptoms, but can be less frequent in older children with small ventricular septal defects, with cardiology visits every few years.

In babies with large ventricular septal defects, they can be seen as often as weekly to closely watch their growth and decide the timing of surgery.

Babies who have shown some signs of congestive heart failure will typically be placed on medicine, usually a diuretic or “water pill,” to help get rid of extra fluid in the lungs.

In babies who are failing to thrive and not growing because it is too difficult for them to eat, a high-calorie formula or fortified breast milk will be added to help the baby grow.

Sometimes babies get worn out with feeding. A small tube may need to be inserted through the nose and into the stomach. This is temporary to help deliver the food. The goal is to get the baby more nutrition to allow the baby more time to grow before surgery.

If the ventricular septal defect is in the muscle or is partially covered by other heart structures, it may get smaller and cause fewer problems over time. If this happens, the infant may not need surgery and will eventually not need medicines.

When the symptoms of a ventricular septal defect are hard to control with medicines or the baby is unable to grow, surgical closure of the defect is often recommended. Surgical closure of isolated ventricular septal defects is uncomplicated in about 99% of cases.

In some patients with multiple ventricular septal defects or other associated heart problems, it is sometimes safer to wait to do a complete repair surgery until the child is bigger. However, if they still have significant symptoms despite medicine, they can undergo a procedure to decrease the amount of blood flow to the lungs. This procedure is called pulmonary artery banding. In this procedure, an artificial band is placed around the outside of the artery that goes to the lungs to make it narrower. This band will then typically be removed later if the patient undergoes surgery for closure of the holes or if the holes become much smaller.

Some ventricular septal defects may be closed using an FDA-approved closure device that is placed using a heart catheter (a small plastic tube through which the device may be delivered). This is done more often in older patients. In infants this requires a limited surgery to be used together with catheter placement of the device.

Long-Term Outlook

Small ventricular septal defects that do not eventually close rarely cause any longer-term difficulties. However, depending on the location of the hole, lifelong follow-up may be needed. This follow-up is to watch for occasional issues that can develop with the valves that may be near the hole or with increased muscle in the ventricle.

Children who have had ventricular septal defects close on their own or closed completely at surgery should not need any medicines and should not be restricted in any way.

Large ventricular septal defects and some moderate ventricular septal defects that have not been closed can cause two problems.

First, infants may have ongoing symptoms of congestive heart failure. Infants who have poor growth due to congestive heart failure can also have poor brain development during the first few years of life. This is the time of most rapid brain development; therefore, good nutrition is important for the development of the baby.

Babies with congestive heart failure are at higher risk for infections, particularly lung infections. If they do get a lung infection, they may not tolerate it as well as other babies and can become sick with even a winter cold. Immunizations may protect against some lung infections, but not all, and complications from these infections can be life-threatening.

Secondly, as the lungs are exposed to excessive pressure and flow over years, the vessels in the lungs may react by developing thicker walls.

The pressures in the lungs will then increase as a result.

The pressures in the lungs can become so high that blue blood (blood with little oxygen) from the right ventricle can flow across the ventricular septal defect into the left ventricle and mix with red blood (blood with oxygen).

The patient will then have a lower level of oxygen in the blood that is going to the rest of the body and will start to develop cyanosis (blue coloring of lips and nails). The high pressures in the lungs may initially be reversed if the hole is closed, but with time will become irreversible and result in failure of the heart. Once permanent changes have occurred in the lungs, it is no longer safe to close the hole. This combination of an unrepaired hole and permanently high pressures in the lungs is called Eisenmenger syndrome.

However, if large ventricular septal defects are diagnosed and managed appropriately, a child with a ventricular septal defect can have a normal length of life with no restrictions.