Free
E-newsletter
Subscribe to Housecall
Our weekly general interest
e-newsletter keeps you up to date
on a wide variety of health topics.
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Causes
By Mayo Clinic staff
Your heart consists of four chambers — two upper chambers (atria) and two lower chambers (ventricles). Within the upper right chamber of your heart (right atrium) is a group of cells called the sinus node. This is your heart's natural pacemaker. The sinus node produces the impulse that normally starts each heartbeat.
Normally, the impulse travels first through the atria and then through a connecting pathway between the upper and lower chambers of your heart called the atrioventricular (AV) node. As the signal passes through the atria, they contract, pumping blood from your atria into the ventricles below. As the signal passes through the AV node to the ventricles, the ventricles contract, pumping blood out to your body.
In atrial fibrillation, the upper chambers of your heart (atria) experience chaotic electrical signals. As a result, they quiver. The AV node — the electrical connection between the atria and the ventricles — is overloaded with impulses trying to get through to the ventricles. The ventricles also beat rapidly, but not as rapidly as the atria. The reason is that the AV node is like a highway on-ramp — only so many vehicles can get on at one time.
The result is a fast and irregular heart rhythm. The heart rate in atrial fibrillation may range from 100 to 175 beats a minute. The normal range for a heart rate is 60 to 100 beats a minute.
Possible causes of atrial fibrillation
Abnormalities or damage to the heart's structure are the most common cause of atrial fibrillation. Possible causes of atrial fibrillation include:
- High blood pressure
- Heart attacks
- Abnormal heart valves
- Heart defects you're born with (congenital)
- An overactive thyroid gland or other metabolic imbalance
- Exposure to stimulants, such as medications, caffeine or tobacco, or to alcohol
- Sick sinus syndrome — functioning of the heart's natural pacemaker
- Emphysema or other lung diseases
- Previous heart surgery
- Viral infections
- Stress due to pneumonia, surgery or other illnesses
- Sleep apnea
However, some people who have atrial fibrillation don't have any heart defects or damage, a condition called lone atrial fibrillation. In lone atrial fibrillation, the cause is often unclear, and serious complications are rare.
Atrial flutter
Atrial flutter is similar to atrial fibrillation, but the rhythm in your atria is more organized and less chaotic than the abnormal patterns common with atrial fibrillation. Sometimes you may have atrial flutter that develops into atrial fibrillation and vice versa. The symptoms, causes and risk factors of atrial flutter are similar to those of atrial fibrillation. For example, strokes are also a concern in someone with atrial flutter. As with atrial fibrillation, atrial flutter is usually not life-threatening when it's properly treated.
- Atrial fibrillation (Afib). Heart Rhythm Society. http://www.hrsonline.org/Patient-Resources/Heart-Diseases-Disorders/Atrial-Fibrillation-AFib. Accessed Dec. 19, 2012.
- Atrial fibrillation. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/af/. Accessed Dec. 19, 2012.
- Verdecchia P, et al. Blood pressure and other determinants of new-onset atrial fibrillation in patients at high cardiovascular risk in the Ongoing Telmisartan Alone and in Combination With Ramipril Global Endpoint Trial/Telmisartan Randomized AssessmeNt Study in ACE intolerant subjects with cardiovascular disease studies. Journal of Hypertension. 2012;30:1004.
- Furie KL, et al. Oral antithrombotic agents for the prevention of stroke in nonvalvular atrial fibrillation: A science advisory for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2012;43:3442.
- Pradaxa (prescribing information). Ridgefield, Conn.: Boehringer Ingelheim Pharmaceuticals; 2012. https://www.pradaxa.com/pradaxa-prescribing-information.jsp. Accessed Dec. 19, 2012.
- Cardioversion. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/crv/. Accessed Dec. 19, 2012.
- Catheter ablation. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/ablation/. Accessed Dec. 19, 2012.
- Cheng J, et al. Surgical approaches to prevent recurrent atrial fibrillation. http://www.uptodate.com/home. Accessed Dec. 19, 2012.
- Kumar K. Antiarrhythmic drugs to maintain sinus rhythm in patients with atrial fibrillation: Recommendations. http://www.uptodate.com/home. Accessed Dec. 19, 2012.
- Wann LS, et al. 2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (updating the 2006 guideline): A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2011;57:223.
- Xarelto (prescribing information). Titusville, N.J.: Jansen Pharmaceuticals; 2012. http://www.xareltorems.com/rems/xarelto-prescribing-information.html. Accessed Dec. 19, 2012.
- How the heart works. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/chd/heartworks.html. Accessed Dec. 19, 2012.
- FDA drug safety communication: Pradaxa (dabigatran etexilate mesylate) should not be used in patients with mechanical prosthetic heart valves. U.S. Food and Drug Administration. http://www.fda.gov/Drugs/DrugSafety/ucm332912.htm. Accessed Dec. 27, 2012.
Find Mayo Clinic on