• Heart Block—Child

    (Atrioventricular [AV] Block—Child)

    Definition

    The heart is comprised of four chambers: two upper chambers (atria) and two lower chambers (ventricles). The sinoatrial (SA) node, located near the top of the right atrium, makes electrical signals that are sent to the atrioventricular (AV) node. The AV node sends the signals to the ventricles, which are the primary pumping chambers of the heart. When the heart is functioning well, the electrical signals are transmitted smoothly from the atria to the ventricles, causing rhythmic muscle contractions that pump blood to the rest of the body.
    Heart block occurs when the electrical signals do not travel normally through the AV node. A heart block does not mean that blood is being blocked from the heart. It means the electricity is not moving normally through the heart, which can make the heart beat more slowly than usual.
    There are three types of heart block, ranging from mild to serious:
    • First-degree heart block—This is the mildest form of heart block. In this case, the electrical signals move more slowly than normal, but all signals reach the ventricles. There are usually no symptoms, and heartbeat and rhythm are normal.
    • Second-degree heart block—A second-degree heart block means that some of the electrical signals are not reaching the ventricles. This causes “dropped beats.”
    • Third-degree, or complete, heart block—This is the most serious type of heart block. In this condition, no electrical signals are able to reach the ventricles. The ventricles compensate by contracting on their own at a much slower rate than is safe for the heart to maintain full function.
    Anatomy of the Heart
    IMAGE
    Copyright © Nucleus Medical Media, Inc.

    Causes

    The causes of heart block in children may include:
    • Heart defect inherited from a parent
    • Medicines
    • Damage from surgery
    • Infections such as Lyme disease
    • Lupus in the mother

    Risk Factors

    Factors that may increase your child's chance of heart block include:
    • Previous heart problems like heart failure or heart attack
    • Heart valve problems
    • Certain medications
    • Exposure to toxic substances

    Symptoms

    If your child experiences any of these symptoms, do not assume it is due to heart block. These symptoms may be caused by other, less serious health conditions. If your child experiences any of them, see the doctor.
    • Dizziness or light-headedness
    • Fainting (syncope)
    • Chest pain
    • Shortness of breath
    • Palpitations
    • Slow heart beat
    • Weakness or fatigue
    Be aware that your child may feel these symptoms, but may not know how to tell you or describe them. Watch out for signs, like if your child has trouble keeping up with other children when playing or if they have “spells” and want to sit down and rest. Your child may also not have any symptoms at all.

    Diagnosis

    The doctor will ask about your child’s symptoms and medical history and do a physical exam. He may also refer your child to a cardiologist (heart doctor) or arrhythmia specialist.
    Tests may include the following:
    • Electrocardiogram (ECG) —a test that records the heart's activity by measuring electrical currents through the heart muscle
    • Echocardiogram —a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart

    Treatment

    The course of treatment will depend on the type of heart block. Generally, treatment is not needed for first-degree heart block. Talk with the doctor about the best treatment plan for your child. Treatment options include a pacemaker . It may be inserted for some cases of second-degree heart block and all cases of third-degree heart block. A pacemaker is a device that generates electrical signals to stimulate heart muscle contractions.
    If your child is diagnosed with heart block, follow the doctor's instructions.

    Prevention

    Unfortunately, there is no way to prevent heart block in your child.

    RESOURCES

    American College of Cardiology http://www.cardiosource.org/acc

    American Heart Association http://www.americanheart.org/

    Heart Rhythm Society http://www.hrsonline.org/

    CANADIAN RESOURCES

    Canadian Cardiovascular Society http://www.ccs.ca/

    Heart and Stroke Foundation of Canada http://ww2.heartandstroke.ca/splash/

    References

    Fauci AS, Braunwald E, Isselbacker KJ, et al. Harrison’s Principles of Internal Medicine . 14th ed. New York, NY: McGraw-Hill; 1998.

    Gregoratos G. Indications and recommendations for pacemaker therapy. Am Fam Physician . 2005;71(8):1563-1570. Also available at: http://www.aafp.org/afp/20050415/1563.pdf . Accessed on August 20, 2005.

    Heart block. American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=4611 . Accessed on August 20, 2005.

    Heart block. Heart Rhythm Society website. Available at: http://www.hrspatients.org/patients/heart%5Fdisorders/heart%5Fblock.asp . Accessed on August 20, 2005.

    University of California San Francisco. Heart block. UCSF Benioff Childrens’ Hospital website. Available at: http://www.ucsfchildrenshospital.org/conditions/heart%5Fblock/ . Updated June 17, 2010. Accessed July 5, 2010.

    Revision Information

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