Ventricular Septal Defect (VSD)

What happens in a VSD

The left ventricle pumps oxygen-rich blood to the body at high pressure. The right ventricle pumps blood to the lungs at much lower pressure. When there is a hole between them, blood flows left to right through the hole, so extra blood circulates through the lungs and returns to the left side of the heart.

The size of the hole determines what happens:

• Small (restrictive) VSD: only a little blood crosses. The heart and lungs cope easily. The fast jet makes a loud murmur.
• Moderate or large VSD: a lot of blood floods the lungs. The left heart enlarges and works harder, causing heart failure symptoms. Over time, high flow can damage the lung blood vessels.

At birth, lung pressures are high, so even large VSDs often cause no symptoms for the first few weeks. As lung pressures fall at about 4 to 8 weeks, the shunt grows and symptoms appear.

Types of VSD

VSDs can also occur as part of more complex defects, such as tetralogy of Fallot, or after a heart attack in adults (septal rupture), which is a different, acquired problem.

Causes and risk factors

Most VSDs happen by chance as the heart forms in the first 8 weeks of pregnancy. Risk is higher with:

• Chromosomal conditions such as Down syndrome, trisomy 13 and 18, and 22q11 deletion
• A parent or sibling with a congenital heart defect
• Maternal diabetes, rubella infection, alcohol use or certain medicines in early pregnancy

Symptoms

Small VSD

• No symptoms
• A loud, harsh murmur, often first heard at the newborn check or in the first weeks

Moderate to large VSD

Symptoms typically appear at 4 to 8 weeks of age:

• Fast or labored breathing
• Sweating, tiring and stopping during feeds
• Poor weight gain despite feeding often
• Frequent chest infections
• Irritability and pale skin

Untreated large VSD

Years of high flow can permanently damage the lung arteries and cause pulmonary hypertension. Eventually blood flows the opposite way, right to left, causing blue skin (cyanosis). This is Eisenmenger syndrome. It is now rare where babies are diagnosed and repaired early.

Diagnosis

• Examination: a harsh murmur at the lower left side of the breastbone. Large holes can, paradoxically, have quieter murmurs.
• Echocardiogram: confirms the diagnosis, size and location of the hole, the direction of flow and the effect on heart chambers. VSDs may also be seen on prenatal ultrasound.
• ECG and chest X-ray: show heart enlargement and lung congestion in larger VSDs.
• Cardiac catheterization: occasionally used to measure lung pressures before surgery in older children or adults.
• Pulse oximetry screening at birth picks up some critical heart defects, though small VSDs usually pass.

Treatment

Watchful waiting

Small VSDs, especially muscular ones, are monitored with periodic echocardiograms. Many close within the first 1 to 2 years, and some later in childhood. Children with small VSDs can usually do all normal activities.

Medicines and nutrition for large VSDs

• Diuretics to remove excess fluid from the lungs
• High-calorie formula or fortified breast milk, sometimes tube feeding, to support growth
• Treatment of infections promptly, and RSV prevention where recommended

Closure

Repair is recommended for large VSDs causing heart failure or poor growth, usually within the first 3 to 6 months, and for some smaller VSDs with complications, such as aortic valve leakage or endocarditis.

• Open-heart surgery: the standard approach. The surgeon closes the hole with a patch or stitches using a heart-lung bypass machine. Mortality is under 1% to 2% in experienced centers for isolated VSDs.
• Catheter device closure: a closure device is passed through a blood vessel and placed across the hole. Used for some muscular VSDs and selected other types, mainly in older children and adults.

Life after VSD repair

Most children recover within a few weeks and grow and develop normally. Possible long-term issues include a small residual leak, heart rhythm problems (heart block in a small number), and valve leakage. Lifelong follow-up with a congenital heart specialist is recommended, less often for simple repaired defects.

Infective endocarditis risk is low for most people with VSDs. Antibiotics before dental work are usually needed only in the first 6 months after device or patch repair, or if there is a residual leak next to prosthetic material. Good dental hygiene matters for everyone with a VSD.

Most women with a repaired or small VSD can have healthy pregnancies, with cardiology review beforehand.

Frequently asked questions

Can a VSD close on its own?

Yes, many small VSDs close without treatment, most often in the first 1 to 2 years. Small muscular VSDs are the most likely to close. Large VSDs and outlet or inlet types rarely close and often need repair.

What are the symptoms of a VSD in a baby?

Babies with small VSDs usually have no symptoms apart from a murmur. Babies with large VSDs develop fast breathing, sweating and tiring during feeds, poor weight gain and frequent chest infections, usually starting at 4 to 8 weeks of age.

Is VSD surgery high risk?

Repair of an isolated VSD is one of the most common pediatric heart operations, with very high success rates and low mortality in experienced centers. Risks include residual leaks and, rarely, heart block needing a pacemaker.

Can adults have a VSD?

Yes. Some adults have small VSDs that never closed, usually with no symptoms. Others have repaired VSDs from childhood. Both need occasional cardiology follow-up. An adult VSD can also develop after a heart attack, which is an emergency.

Can my child play sports with a VSD?

Children with small VSDs, or VSDs that have been repaired with good results, can usually take part in all sports. Your child's cardiologist will advise if there are rhythm problems, pulmonary hypertension or other concerns.