Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Atrial Fibrillation

by Debra Wood, RN
Definition

Atrial fibrillation is an abnormal heart rhythm. The heart's electrical system normally sends regularly spaced, predictable signals, telling the heart muscle to contract, or beat.

The heart has two upper chambers, called atria, and 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 quiver, rather than contract. Some signals do not reach the ventricles and the ventricles continue pumping, usually irregularly and sometimes rapidly. This uncoordinated rhythm can reduce the heart’s efficiency at pumping blood out to the body. Blood left in the heart chambers can form clots. These clots may sometimes break away, travel to the brain, and cause a stroke .

Causes

In most cases, atrial fibrillation is due to an existing heart condition. But atrial fibrillation can occur in people with no structural heart problems. A thyroid disorder or other condition may cause the abnormal rhythm. In some cases, the cause is unknown.

Risk Factors

Risk factors include:

Symptoms

Symptoms can vary from mild to severe, depending on your heart function and overall health. Some people may not notice any symptoms.

Symptoms include:

  • Dizziness, lightheadedness, or fainting
  • Exercise intolerance
  • Fatigue or weakness
  • Irregular or rapid pulse or heart beat
  • Pain or pressure in the chest
  • Palpitations, or a pounding feeling in the chest
  • Racing feeling in the chest
  • Shortness of breath
  • Sweating
Diagnosis

The doctor will:

  • Ask about your symptoms and medical history
  • Listen to your heart with a stethoscope
  • Perform a physical exam

Tests may include:

  • 24-hour holter monitoring—wearing a heart monitor that records the heart rhythm for 24-hours
  • Blood tests—to look for underlying conditions
  • Chest x-ray —to look for underlying conditions
  • Coronary angiography —x-rays taken after a dye is injected into the coronary arteries
  • Echocardiogram —a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
  • Electrocardiogram (ECG, EKG) —a test that records the heart's activity by measuring electrical currents through the heart muscle
Treatment

The goals of treatment are to:

  • Keep heart rate as close to normal
    • Your doctor will tell you what your target heart rate is. In general, the your resting rate should be between 60-80 beats per minute, and 90-115 beats per minute during moderate exercise.
  • Prevent blood clots from forming
  • Restore a regular rhythm, if possible

If an underlying cause of atrial fibrillation is found, it may be treated. Some patients return to a normal rhythm without treatment.

Treatments include:

Medication
  • Drugs to keep the heart in a regular rhythm, such as:
    • Amiodarone
    • Propafenone
    • Sotalol
  • Drugs to prevent clot formation, such as warfarin
  • Drugs to slow the heart rate, such as:
    • Atenolol
    • Digitalis
    • Diltiazem
    • Metoprolol
    • Verapamil
Cardioversion

Cardioversion is a procedure that uses an electrical current or drugs to help normalize the heart rhythm. If atrial fibrillation has lasted 48 hours or more, you may be given blood thinners before this procedure.

Ablation Therapy

In some cases, an area of the atria that is deemed to be responsible for the atrial fibrillation may be surgically removed or altered (ablated) with various techniques, including cryoablation or radiofrequency ablation , to prevent it from persistently generating the rhythm disturbance.

Lifestyle Changes

Avoid caffeine and other stimulants because they may trigger another episode. Alcohol may also act as a trigger in some people.

If you are diagnosed with atrial fibrillation, follow your doctor's instructions .

Prevention

If you have risk factors for atrial fibrillation, avoid known triggers, such as alcohol and caffeine. Follow your doctor's advice for controlling heart disease, high blood pressure, and other conditions.

Last reviewed: September 2011 by Michael J. Fucci, DO.

RESOURCES:
CANADIAN RESOURCES:
References:
  • American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation—executive summary. Circulation. 2006;114:700-752.
  • American Heart Association. AHA medical/scientific statement: management of patients with atrial fibrillation.1996.
  • Dambro MR. Griffith's 5-Minute Clinical Consult . Philadelphia, PA: Lippincott Williams and Wilkins; 2001.
  • Duthie EH, Katz PR. Practice of Geriatrics . 3rd ed. Philadelphia, PA: WB Saunders Company; 1998.
  • Fauci AS, Braunwald E, Isselbacher KJ, et al. Harrison's Principles of Internal Medicine . 14th ed. New York, NY: The McGraw-Hill Companies; 2000.
  • Rakel RE and Bope ET. Conn's Current Therapy 2001 . 53rd ed. Philadelphia, PA: WB Saunders Company; 2001.
  • 12/13/2010 DynaMed's Systematic Literature Surveillance 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.