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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 hearts 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 .
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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.
A risk factor is something that increases your chance of getting a disease or condition.
Cardiovascular diseases: High blood pressureCoronary artery diseaseCongestive heart failureHeart attackHeart valve diseaseEndocarditis (infection of a heart valve) Cardiomyopathy (disease of the heart muscle) Congenital heart diseasePrior episode of atrial fibrillation Lung diseases: EmphysemaAsthmaBlood clots in the lungsAge: 55 or olderSmoking Chronic medical conditions: Overactive thyroidDiabetesExcessive alcohol intakeUse of stimulant drugs, including caffeineSex: male Undergoing general anesthesiaStress, either emotional or physical SymptomsSymptoms can vary from mild to severe, depending on your heart function and overall health. Some people may not notice any symptoms. Symptoms include: Irregular or rapid pulse or heart beatRacing feeling in the chestPalpitations, or a pounding feeling in the chestDizziness, lightheadedness, or faintingSweatingPain or pressure in the chestShortness of breathFatigue or weaknessExercise intolerance Diagnosis The doctor will: Ask about your symptoms and medical historyPerform a physical examListen to your heart with a stethoscope Tests may include:
Electrocardiogram (ECG, EKG) a test that records the heart's activity by measuring electrical currents through the heart muscle 24-hour holter monitoringwearing a heart monitor that records the heart rhythm for 24-hoursEchocardiogram a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart Coronary angiography x-rays taken after a dye is injected into the coronary arteries Chest x-ray to look for underlying conditions Blood teststo look for underlying conditions Treatment The goals of treatment are to: Restore a regular rhythm, if possibleKeep heart rate as close to normal as possiblePrevent blood clots from formingIf 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 slow and regulate heart rate, such as: DigitalisVerapamilDiltiazemPropranololQuinidineProcainamideOther antiarrhythmic drugs Drugs to prevent clot formation, called anticoagulants or blood thinners, such as: AspirinWarfarin CardioversionCardioversion 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 ChangesAvoid caffeine and other stimulants because they may trigger another episode. Alcohol may also act as a trigger in some people. PreventionIf 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. RESOURCES: American Heart Associationhttp://www.americanheart.org Atrial Fibrillation Foundationhttp://www.affacts.org CANADIAN RESOURCES: Canadian Cardiovascular Societyhttp://www.ccs.ca/home/index_e.aspx Canadian Family Physicianhttp://www.cfpc.ca/cfp/ References: American Heart Association. AHA medical/scientific statement: management of patients with atrial fibrillation.1996. Dambro MR. Griffith's 5-Minute Clinical Consult . 2001 ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2001.
Duthie EH Jr and 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. Last reviewed December 2007 by J. Peter Oettgen, MDPlease 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.