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    Endocardial cushion defect

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

    Endocardial cushion defect (ECD) is an abnormal heart condition in which 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.


    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.
    • Irritation and swelling. This is caused by increased blood flow into the lungs.
    • 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, 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, often letting blood leak back through the valve.

    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 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


    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 in the baby's first year of life, 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.

    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


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


    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.


    • Congenital heart defect ...


    • Ventricular septal defec...


    • Atrial septal defect


    • Atrioventricular canal (...


    • Congenital heart defect ...


    • Ventricular septal defec...


    • Atrial septal defect


    • Atrioventricular canal (...


    A Closer Look

      Self Care

        Tests for Endocardial cushion defect

          Review Date: 6/5/2012

          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. Health Solutions, Ebix, Inc.

          The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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