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Atrial Fibrillation

  • Definition

    Atrial fibrillation is an abnormal heart rhythm. The heart's electrical system normally sends regularly spaced signals. These signals tell the heart muscle to contract or beat.
    The heart has two upper chambers called atria. It also has two lower chambers called ventricles. Each signal starts in the atria and travels to the rest of the heart. In atrial fibrillation, the electrical signals from the atria are fast and irregular. The atria shake instead of contract. Some signals do not reach the ventricles and the ventricles continue pumping. This pumping is usually irregular and sometimes rapid. This rhythm can reduce the heart’s ability to pump blood out to the body. Blood left in the heart chambers can form clots. These clots may sometimes break away and travel to the brain. This can cause stroke.
    Atrial Fibrillation
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  • Causes

    In most cases, atrial fibrillation is due to an existing heart condition. Atrial fibrillation can also occur in people who do not have structural heart problems. A thyroid disorder or other condition may cause the abnormal rhythm. The cause of atrial fibrillation is sometimes unknown.
  • Risk Factors

    Factors that may increase the risk of atrial fibrillation include:
  • Symptoms

    Symptoms can be mild to severe. This depends on your heart function and overall health. Some people may not notice any symptoms.
    Symptoms include:
    • Irregular or rapid pulse or heart beat
    • Racing feeling in the chest
    • A pounding feeling in the chest
    • Dizziness, lightheadedness, or fainting
    • Sweating
    • Pain or pressure in the chest
    • Shortness of breath
    • Fatigue or weakness
    • Unable to exercise
  • Diagnosis

    The doctor will:
    • Ask about your symptoms and medical history
    • Perform a physical exam
    • Listen to your heart with a stethoscope
    You doctor will order blood tests to help diagnose the problem.
  • Treatment

    The goals of treatment are to:
    • Return your heart to a regular rhythm, if possible.
    • Keep your heart rate close to normal.—Your doctor will tell you your target heart rate. In general, your resting rate should be between 60-80 beats per minute. It should be 90-115 beats per minute during moderate exercise.
    • Prevent blood clots from forming.
    Your doctor may find another condition that is causing atrial fibrillation. This condition may be treated. In some cases, heart rhythm problems return to normal without treatment.
    Treatment options include:
    • Drugs to slow the heart rate, such as digitalis, verapamil, diltiazem, metoprolol, atenolol
    • Drugs to keep the heart in a regular rhythm, such as sotalol, propafenone, amiodarone
    • Drugs to prevent clot formation, such as warfarin, dabigatran, rivaroxaban
    Weight Management
    Maintaining a healthy weight through diet and exercise may reduce the frequency, duration, and severity of atrial fibrillation episodes.
    • Cardioversion—This procedure uses an electrical current or drugs to help normalize the heart rhythm.
    • Ablation—An area of the heart that is responsible for atrial fibrillation may be surgically removed or altered (ablated) with various techniques.
    • Maze procedure and mini-maze procedure—The Maze procedure creates a pattern of scar tissue in the upper chambers of the heart. This makes a pathway for electrical impulses to travel through the heart. It also blocks the pathway for fast or irregular impulses. The Maze procedure may also be performed as minimally invasive surgery (called mini-Maze ).
    Lifestyle Changes
    Your doctor may recommend that you make lifestyle changes, such as:
    • Avoiding certain substances (e.g., caffeine and other stimulants, alcohol) that may trigger another episode
    • Having a regular exercise routine
    Follow your doctor's instructions if you are diagnosed with atrial fibrillation.
  • Prevention

    Avoid known triggers if you have risk factors for atrial fibrillation. Also, follow your doctor's advice for controlling chronic conditions, like heart disease and high blood pressure.

    American Heart Association

    Heart Rhythm Society


    Canadian Cardiovascular Society

    Canadian Family Physician


    Atrial fibrillation. CardioSmart website. Available at: Accessed November 9, 2012.

    Cardioversion. EBSCO Health Library website. Available at: Accessed January 30, 2008.

    Cardioversion procedure. Cleveland Clinic website. Available at: Updated December 28, 2011. Accessed November 9, 2012.

    What is atrial fibrillation? National Heart Lung and Blood Institute website. Available at: Updated July 1, 2011. Accessed November 9, 2012.

    12/13/2010 DynaMed's Systematic Literature Surveillance Lubitz SA, Yin X, Fontes JD, et al. Association between familial atrial fibrillation and risk of new-onset atrial fibrillation. JAMA. 2010;304(20):2263-2269.

    5/11/2012 DynaMed's Systematic Literature Surveillance Osbak PS, Mourier M, Kjaer A, Henriksen JH, Kofoed KF, Jensen GB. A randomized study of the effects of exercise training on patients with atrial fibrillation. Am Heart J. 2011;162(6):1080-1087.

    1/2/2014 DynaMed's Systematic Literature Surveillance Abed HS, Wittert GA, et al. Effect of weight reduction and cardiometabolic risk factor management on symptom burden and severity in patients with atrial fibrillation: a randomized clinical trial. JAMA. 2013 Nov 20;310(19):2050-2060.

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