Causes

Endocardial cushion defect occurs while a baby is still growing in the womb. The endocardial cushions are two areas of thickening that eventually develop into the wall (septum) that separates the four chambers of the heart. They also form the mitral and tricuspid valves, 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 persons with this condition, blood flows through the abnormal openings from the left to the right side of the heart, then to the lungs. The increased blood flow into the lungs leads to a rise in blood pressure in the lungs.
• Lung irritation and inflammation. Increased blood flow into the lungs causes irritation and swelling.
• Heart failure. Because the heart has to pump more blood to the lungs, it has to work much harder than normal. The heart 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, and 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: A complete ECD involves an atrial septal defect (ASD) and a ventricular septal defect (VSD). Persons 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: Only an ASD is present. There are two distinct valves, but one of them (the mitral valve) is often abnormal with an opening ("cleft") in it, letting blood leak between the two left chambers of the heart.

ECD is strongly associated with 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:

• Double outlet right ventricle
• Single ventricle
• Transposition of the great vessels
• Tetralogy of Fallot

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 separate the common valve into distinct tricuspid and mitral valves. The timing of the surgery depends on the child's condition and the severity of the ECD. It can usually be done when the baby is 3 - 6 months old. Correcting an ECD may require more than one surgery.

Your doctor may prescribe medication before surgery if the ECD has made your baby very sick. The medicines will help the child gain weight and strength before surgery. Medications may 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 as early in the baby's first year of life as possible, before irreversible lung damage occurs. Babies with Down syndrome tend to develop lung disease earlier, and therefore early surgery is very important for these babies.

See also:

• Congenital heart defect corrective surgery
• Pediatric heart surgery

Outlook (Prognosis)

Possible Complications

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.

Children with congenital heart disease may need to take antibiotics before dental treatment. This helps prevent complications related to heart infections. Ask a cardiologist whether your child needs to take antibiotics.

When to Contact a Medical Professional

Prevention

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

Alternative Names

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

References

Park MK. Pediatric Cardiology for Practitioners, 5th ed. Philadelphia, Pa: Mosby Elsevier; 2008:181-189:chap 12.

Townsend Jr. CM, Beauchamp RD, Evers BM, et al. Sabiston Textbook of Surgery, 18th ed. Philadelphia, Pa: Saunders Elsevier; 2008:1760-1762.

Update Date: 4/30/2012

Reviewed by: Kurt R. Schumacher, MD, Pediatric Cardiology, University of Michigan Congenital Heart Center, Ann Arbor, MI. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.