• Bradycardia



    Bradycardia is an abnormally slow heart rate. In adults, it is defined as a heart rate of less than 60 beats per minute. Different types of bradycardia are collectively referred to as bradyarrhythmias. They include:
    • Sinus bradycardia—an unusually slow heartbeat due to heart disease, a reaction to medication, or harmless causes, such as excellent fitness or deep relaxation
    • Sick sinus syndrome—an unusually slow heartbeat due to a malfunction of the sinoatrial node, which is the heart's natural pacemaker
    • Heart block (atrioventricular block or AV block)—an unusually slow heartbeat due to a slowing or blocking of electrical impulses in the heart’s conduction system
    Heartbeat: Anatomy of the Heart
    Copyright © Nucleus Medical Media, Inc.


    Bradycardia may be caused by:
      Normal responses to:
      • Deep relaxation
      • Being in excellent physical shape
    • The heart’s natural pacemaker developing an abnormal rate or rhythm
    • The normal electrical conduction pathway being interrupted
    • Another part of the heart taking over as pacemaker

    Risk Factors

    Risk factors that increase your chance of getting bradycardia include:


    Some types of bradycardia produce no symptoms. Others may cause noticeable symptoms, such as:
    • Fainting or loss of consciousness
    • Dizziness or light-headedness
    • Weakness
    • Mild fatigue
    • Irregular heart beat
    • Shortness of breath
    • Chest pain
    Serious forms of bradycardia, such as complete heart block, are medical emergencies. They can lead to loss of consciousness or sudden cardiac arrest .


    The doctor will ask about your symptoms and medical history. A physical exam will be done. Your heart will be examined with a stethoscope.
    • Your doctor may need you to have blood tests. These tests will look for problems that may explain the bradycardia.
    • Your doctor may need to test your heart function. This can be done with:


    Treatment may not be required if you do not have cardiac symptoms and conditions. Your doctor may choose to monitor your heart rate and rhythm instead.
    Treatment may include:
    • Stopping any medications that slow the heart rate
    • Diagnosing and treating any underlying conditions
    • Medication to temporarily increase your heart rate
    • An artificial pacemaker to establish and maintain a normal heart rhythm


    To help prevent bradycardia:
    • Treat conditions that might lead to bradycardia.
    • Carefully follow your doctor’s directions when using medications, especially those that can cause bradycardia.
    • Check with your physician or pharmacist before using any over-the-counter medication or natural supplement. Make sure it does not interact with your other medications.
    • Follow general advice for preventing heart disease, including:
      • Maintain a healthy weight.
      • Consult with your doctor about a safe exercise program.
      • Avoid smoking.
      • Eat a healthy diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.
      • Treat your high blood pressure and/or diabetes .
      • Treat your high cholesterol or triglycerides.


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

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

    National Heart, Lung, and Blood Institute http://www.nhlbi.nih.gov/


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

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


    Bradycardia. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Bradycardia%5FUCM%5F302016%5FArticle.jsp . Updated October 25, 2012. Accessed January 18, 2013.

    Fleg J. Arrhythmias and conduction disturbances. In: Beers MH, Berkow R, eds. The Merck Manual of Geriatrics [online]. Merck & Co.; 2000:486.

    Hurst's The Heart . 11th ed; 2004.

    What is an arrhythmia? National Heart, Lung and Blood Institute, National Institutes of Health website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/arr/ . Updated July 1, 2011. Accessed January 18, 2013.

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