Endocardial cushion defect

 

Alternative Names

Atrioventricular (AV) canal defect; Atrioventricular septal defect; AVSD

Definition

Endocardial cushion defect (ECD) is an abnormal heart condition. The walls separating all four chambers of the heart are poorly formed or absent. It is a congenital heart disease, which means it is present from birth.

Causes

Endocardial cushion defect occurs while a baby is still growing in the womb. The endocardial cushions are two thicker areas that go on to develop into the wall (septum) that separates the four chambers of the heart. They also form the mitral and tricuspid valves. These are the valves that separate the atria (top collecting chambers) from the ventricles (bottom pumping chambers).

The lack of separation between the two sides of the heart causes several problems:

  • Increased blood pressure in the lungs. In people with this condition, blood flows through the abnormal openings from the left to the right side of the heart, then to the lungs. More blood flow into the lungs makes the blood pressure in the lungs rise.
  • Irritation and swelling. This is caused by increased blood flow into the lungs.
  • Heart failure. The extra effort needed to pump makes the heart work harder than normal. The heart muscle may enlarge and weaken.
  • Cyanosis. As the blood pressure increases in the lungs, blood flow starts to move from the right side of the heart to the left. The oxygen-poor blood mixes with the oxygen-rich blood. As a result, blood with less oxygen than usual is pumped out to the body. This causes cyanosis, or bluish coloring of the skin.
 

There are two types of ECD:

  • Complete ECD. This condition involves an atrial septal defect (ASD) and a ventricular septal defect (VSD). People with a complete ECD have only one large heart valve (common AV valve) instead of two distinct valves (mitral and tricuspid).
  • Partial (or incomplete) ECD. In this condition, only an ASD, or an AD and VSD are present. There are two distinct valves, but one of them (the mitral valve) is often abnormal with an opening ("cleft") in it. This defect can leak blood back through the valve.

ECD is strongly linked to Down syndrome. Several gene changes are also connected to ECD. However, the exact cause of ECD is unknown.

ECD may be associated with other congenital heart defects, such as:

Symptoms

Symptoms of ECD may include:

  • Baby tires easily
  • Bluish skin color (the lips may also be blue)
  • Failure to gain weight and grow
  • Frequent pneumonia
  • Lack of appetite
  • Pale skin (pallor)
  • Rapid breathing
  • Rapid heartbeat
  • Sweating
  • Swollen legs or abdomen (rare in children)
  • Trouble breathing, especially during feeding

Exams and Tests

Signs of ECD may include:

  • An abnormal electrocardiogram (ECG)
  • An enlarged heart
  • Heart murmur

Children with partial ECD, who have only a small VSD and normal valves, may not have signs or symptoms of the disorder during childhood.

Tests to diagnose ECD include:

  • Ultrasound of the heart (echocardiogram) to see blood flow
  • An electrocardiogram (ECG), which measures the electrical activity in the heart
  • Chest x-ray, which may show an enlarged heart
  • Magnetic resonance imaging (MRI) of the heart, which provides a detailed image of the heart through the use of powerful magnets
  • Cardiac catheterization (in some cases), a procedure in which a thin tube (catheter) is placed into the heart to see blood flow and take accurate measurements of blood pressure and oxygen levels

Treatment

Surgery is needed to close the holes between the heart chambers, and to create distinct tricuspid and mitral valves. The timing of the surgery depends on the child's condition and the severity of the ECD. It can often be done when the baby is 3 - 6 months old. Correcting an ECD may require more than one surgery.

Your doctor may prescribe medicine before surgery if the ECD has made your baby very sick. The medicines will help the child gain weight and strength before surgery. Drugs often used include:

  • Diuretics (water pills)
  • Drugs that make the heart contract more forcefully (inotropic agents), such as digoxin

Surgery for a complete ECD should be done in the baby's first year of life. Otherwise, lung damage that may not be able to be reversed can occur. Babies with Down syndrome tend to develop lung disease earlier. Therefore, early surgery is very important for these babies.

Outlook (Prognosis)

How well your baby does depends on the severity of the ECD, the child's overall health, and whether lung disease has already developed. Many children live normal, active lives after the ECD is corrected.

Complications from ECD may include:

  • Congestive heart failure
  • Death
  • Eisenmenger syndrome
  • High blood pressure in the lungs
  • Irreversible damage to the lungs

Certain complications of ECD surgery may not appear until the child is an adult. These include heart rhythm problems and a leaky mitral valve.

Ask a cardiologist whether your child needs to take antibiotics before dental treatment or other procedures.

When to Contact a Medical Professional

Call your health care provider if your child:

  • Tires easily
  • Has trouble breathing
  • Has bluish skin or lips

Also talk to your health care provider if your baby is not growing or gaining weight.

Prevention

ECD is linked with several genetic abnormalities. Couples with a family history of ECD may wish to seek genetic counseling before becoming pregnant.

References

Scholz TD, Reinking BE. Congenital heart disease. In: Gleason CA, Devaskar S, eds. Avery's Diseases of the Newborn. 9th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 55.

Review Date: 5/14/2014
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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