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Atrioventricular Septal Defect

An atrioventricular septal defect (AVSD) is a heart defect in which there are holes between the chambers of the heart's right and left sides. The valves that control the blood flow between these chambers may not be formed correctly.

Two general types of AVSD can occur, depending on which structures are not formed correctly:

  • Complete AVSD: A complete AVSD occurs when there is a large hole in the center of the heart, which allows blood to flow between all four chambers of the heart. This hole occurs where the septa (walls) separating the two top chambers (atria) and two bottom chambers (ventricles) usually meet

  • Partial or Incomplete AVSD: A partial or incomplete AVSD occurs when the heart has some but not all of the defects of a complete AVSD. There is usually a hole in the atrial wall or the ventricular wall near the center of the heart. A partial AVSD usually has both mitral and tricuspid valves. One of the valves (usually mitral) may not close completely, allowing blood to leak backward from the left ventricle into the left atrium.

What happens once you have AVSD?

In AVSD, blood flows where it normally should not. The blood may also have a lower than normal amount of oxygen, and extra blood can flow to the lungs. This extra blood being pumped into the lungs forces the heart and lungs to work hard and may lead to congestive heart failure (CHF).

Infants who have surgical repairs for AVSD might still have lifelong complications. The most common of these complications is a leaky mitral valve. This is when the mitral valve does not close all the way so the heart has to work harder to get enough blood to the rest of the body.

When symptoms do occur, they may include:

  • Weak pulse.

  • Tiring easily.

  • Pounding heart.

  • Breathing problems.

  • Swelling of the legs or belly.

  • Ashen or bluish skin color.

  • Poor feeding, slow weight gain.

For partial AVSDs, if the holes between the chambers of the heart aren't large, the signs and symptoms might not be diagnosed for years.

Symptoms that might indicate that a child’s complete AVSD or partial AVSD is getting worse include:

  • Arrhythmia: An abnormal heart rhythm can cause the heart to beat too fast, too slow, or erratically. When the heart does not beat properly, it can’t pump blood effectively.

  • Congestive heart failure: With this disease, the heart cannot pump enough blood and oxygen to meet the body's needs.

  • Pulmonary hypertension: This type of high blood pressure affects the arteries in the lungs and the heart's right side.

What causes AVSD?

The causes of congenital heart defects, such as AVSD, among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. AVSD is common in babies with Down syndrome, a genetic condition that involves an extra chromosome 21 (also called trisomy 21).

Congenital heart defects are also thought to be caused by environmental factors, such as what the mother eats or drinks or certain medications she uses during pregnancy.

What types of tests are used to diagnosis AVSD?

A heart murmur is often the first clue that this heart defect exists. It is typically noted in the first week or two of life and it is not uncommon that no murmur is present at birth.

The diagnosis of AVSD in any form is easily made by an echocardiogram or fetal echocardiogram. Chest X-ray and an electrocardiogram may be used to assist in the assessment. Both may show characteristic findings in AVSDs.

Because of the high incidence of AVSDs in infants with Down syndrome, all infants with Down syndrome should have an echocardiogram, even if they do not have a heart murmur or any of the signs or symptoms discussed above.

What types of treatments and procedures are used to treat AVSD?

Both partial and complete AVSD types usually require surgery. During surgery, any holes in the chambers are closed using patches. If the mitral valve does not close completely, it is repaired or replaced. For a complete AVSD, the common valve is separated into two distinct valves.

The age at which surgery is done depends on the child’s health and the structure of the AVSD. If possible, surgery should be done before permanent damage to the lungs from too much blood being pumped to the lungs.

Medication may be used to treat congestive heart failure, but it is only a short term measure until the infant is healthy enough for surgery.

What can I do to support my health when I have AVSD?

Infants who have surgical repairs for AVSD are not cured; they might have lifelong complications. The most common complication is a leaky mitral valve. Therefore, a child or adult with an AVSD will need regular follow-up visits with a cardiologist (heart doctor) to monitor their progress, avoid complications, and check for other health conditions that might develop over time.

With proper treatment, most babies with AVSD grow up to lead healthy, productive lives.

Why choose Presbyterian for AVSD treatment?

Presbyterian’s Pediatric and Congenital Cardiology team has many different options to help you manage your or your child’s heart condition. The team performs various diagnostic tests and procedures to help form an accurate diagnosis and create individualized treatment plans. Depending on the type of heart condition your child has and its underlying cause, the team can recommend a wide variety of treatment options. Our pediatric cardiologists, pediatric interventional cardiologists, and pediatric cardiovascular surgeons work closely together for cases in which cardiac repair or surgery is the best treatment option.