A ventricular septal defect (VSD) is a congenital heart defect, or problem with the heart’s structure that is present at birth. There are many types of congenital heart defects, and a VSD is the most common. Essentially, it is an abnormal hole in the wall that divides the two lower chambers of the heart, called the ventricles. Depending on its size, the hole can disrupt blood flow to the lungs, raising the risk of such serious problems as arrhythmia, high blood pressure, and stroke.

“First, we try to use medical management to mitigate the effects of the VSD. However, when those are unable to solve the problem, we can close the hole surgically and, sometimes, noninvasively in the catheterization lab," says Katherine Kosiv, MD, a Yale Medicine pediatric cardiologist who specializes in cardiac imaging and fetal cardiology.

The heart is made up of four chambers. A ventricular septal defect is an abnormal opening on the wall (or septum) that separates the heart’s two lower chambers, or ventricles, which are also the blood’s main pumping chambers.

In a person with a normal heart, blood moves from the heart’s right ventricle to the lungs, where it is enriched with oxygen before the left ventricle pumps it to the rest of the body. But a VSD can allow blood to flow from the left ventricle back to the right one, which can cause extra fluid to build up, forcing the lungs and heart to do extra work. This unnecessary extra work ultimately causes babies to breathe faster and burn more calories.

The Centers for Disease Control and Prevention estimates that 1 in 240 babies born in the United States has a VSD. The problem is usually diagnosed in infancy, but can also be identified prenatally (before the baby is born) or at any time, including in adulthood.

Some VSDs cause no symptoms at all, especially if the hole is small. In fact, small VSDs often don’t require treatment. A medium-sized or large hole is often detected when a doctor hears an unusual swishing sound (called a murmur) while listening to the heart with a stethoscope; the sound is the noise the blood makes when it flows through the hole.

In babies, other symptoms may appear in the first days or months. They might include:

• Fatigue
• Poor appetite and growth
• Fast breathing or shortness of breath
• Fatigue during feeding and problems with weight gain
• Sweating

Adults should talk to their doctor if they notice:

• Weakness or tiredness
• An irregular or rapid heartbeat
• Shortness of breath when lying down or exercising

If a large VSD isn’t treated, the abnormal flow of blood may eventually damage the lungs. This can raise the risk of a variety of problems, including Eisenmenger’s syndrome, a complication characterized by increased blood pressure in the lungs. Large VSDs that aren’t treated also can lead to such serious issues as arrhythmia and stroke.

A specialist who suspects a patient may have a VSD may order imaging tests, such as an echocardiogram, an ultrasound of the heart, and an electrocardiogram that can track the heart's electrical activity. A fetal echocardiogram can diagnose a VSD in a baby in utero, or before it is born.

Some small VSDs won’t require any treatment at all—many will close on their own—but it’s important for a congenital heart specialist to continue to monitor them. Medication may be necessary to support heart function until the VSD can be treated. Some babies with the condition require nutritional support.

Large holes may need to be closed if they cause symptoms. Most of the time, the hole will require surgical closure. Open heart surgery involves general anesthesia and the use of a heart-lung machine to support circulation so that the surgeon can make an incision in the chest and sew the hole shut or plug it with a synthetic patch.

There are also specific situations when the hole can be closed noninvasively via a catheterization procedure that involves inserting a thin, flexible tube through the leg and up to the heart, where a special implant made of wire mesh implant is positioned to seal the hole.

Most patients who are treated for a VSD—or who have a small one that closes on its own—have few complications. Most can expect to live healthy, active lives. But people who have a VSD that has not been treated may be at risk for endocarditis, an infection that can occur in the heart.

Yale Medicine Pediatric Cardiology has extensive experience caring for infants and children with VSDs and other congenital heart problems. From our fetal cardiologists who diagnose VSD prenatally to our Adult Congenital Heart Program, which extends care to adults of all ages, we provide patients the option of seamless care from before birth to adulthood. Our specialists take a team approach to each case, bringing together pediatric cardiac surgeons, pediatric cardiologists, neonatologists, intensivists, child life specialists, and other experts.

Our specialists are members of the comprehensive Children’s Heart Center at Yale New Haven Children’s Hospital and other Yale Medicine specialty clinics and programs.