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Atrial Fibrillation
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About Atrial Fibrillation


Atrial fibrillation is the most common form of irregular heartbeat (arrhythmia). Normally, your heart's intrinsic electrical conduction system controls the systematic rhythm at which the atria (upper chambers) and ventricles (lower chambers) contract in a coordinated manner. In atrial fibrillation, abnormal electrical impulses cause the two upper chambers of the heart to fibrillate, or quiver, resulting in ineffective and uncoordinated rhythm of contraction between the upper and lower chambers. This makes the ventricles beat irregularly, which leads to an irregular (and usually fast) pulse. As a result, the heart pumps less efficiently, reducing blood flow to the body and to the heart muscle itself. (See cardiac anatomy)

Atrial fibrillation may be a sporadic condition, where it comes and goes, or it may be a constant, chronic condition.

Incidence and Causes
More than 2 million Americans have atrial fibrillation. It's increasingly common with advancing age and affects less than 1 percent of Americans younger than 60, but as many as one in 10 people older than 80.(1) Atrial fibrillation can also occur as a result of heart disease, high blood pressure, lung disease, thyroid disease, Diabetes, use of alcohol or stimulants (excessive caffiene, nicotine, illegal drugs, theophylline, or decongestants).(2)
Symptoms

Some people with atrial fibrillation have no symptoms and are unaware of their condition until their doctor discovers it during a physical examination.

Others might have one or more of the following symptoms :

  • Sensation of feeling the heart beat (palpitations)
  • Pulse may feel rapid, racing, pounding, fluttering, or it can feel too slow
  • Pulse may feel regular or irregular
  • Dizziness, light-headedness, or fainting
  • Confusion
  • Fatigue
  • Shortness of breath
  • Breathing difficulty while lying down
  • Sensation of tightness in the chest
Symptoms may come and go, lasting for a few minutes to hours and then stopping on their own. Or they may be chronic, lasting until they are treated.
Complications of Atrial Fibrillation

Although atrial fibrillation usually isn't life-threatening, it can lead to significant complications:

  • Stroke: Inefficient pumping of the atria can allow abnormal pooling of the blood which can result in the formation of a blood clot. If these clots are pumped out of the heart and into the bloodstream, they can lodge in the brain's blood vessels, resulting in a stroke. For this reason, anticoagulant medications are often prescribed for patients with atrial fibrillation.
  • Heart attack or heart failure: If the heart rate is fast and uncontrolled over a long period of time, atrial fibrillation can weaken the heart muscle and cause it to dilate or stretch out. This can increase the risk of heart attack, heart failure, cardiomyopathy, or stroke.
Treatment

Atrial fibrillation (AF) is a progressive condition that requires regular medical attention, but with treatment, people can live normal, active lives. For some people, treatment can cure AF and return their heartbeat to a normal rhythm. For others who have permanent AF, treatment can successfully control symptoms and prevent complications. Treatment varies from person to person depending on many factors.

1) Medications: Anticoagulant medications, such as heparin, warfarin (Coumadin), and aspirin, are used to reduce the risk of blood clot formation. Beta-blockers, calcium channel blockers, and digoxin, are often used to slow down a rapid heart rate. Antiarrhythmic medications are sometimes used to try to maintain a normal rhythm. However, for some people, antiarrhythmic medications may not be the preferred treatment. If infection, hyperthyroidism, or heart failure is the cause of atrial fibrillation, medications are used to control heart rate while the underlying cause is treated.

2) Electrical Cardioversion is used, in certain patients with atrial fibrillation, to restore a normal sinus rhythm if the heart rhythm does not convert on its own. Electrical cardioversion uses an electrical current to stop the heart momentarily. A split-second electrical shock is delivered through the chest wall to the heart through special electrodes or paddles that are applied to the skin of the chest and back. This helps the heart obtain a normal rhythm when it resumes beating.

3) Drugs (such as ibutilide) can sometimes restore the heart's normal rhythm. These drugs are given under medical supervision, and are delivered through an IV tube into a vein, usually in the patient's arm.

4) Catheter Ablation: If the above treatments fail and the patient continues to be bothered by symptoms, radiofrequency ablation may be used to block abnormal pathways. In this procedure, thin and flexible tubes are introduced through a blood vessel and directed to the heart muscle. Then a burst of radiofrequency energy is delivered to destroy tissue that triggers abnormal electrical signals or to block abnormal electrical pathways.

5) Surgery can be a method to disrupt the electrical pathways that cause AF

6) Atrial pacemakers can be implanted under the skin to regulate the heart rhythm

Prevention

A healthy lifestyle:

  • Don't smoke
  • Maintain a healthy weight,
  • Eat heart healthy foods which are are low in saturated fat, trans fat, and cholesterol and also include a variety of grains, fruits, and vegetables.
  • Follow a regular exercise program
  • Treat high blood pressure
  • Try to control stress levels
  • Avoid excessive caffeine and other stimulants
  • If you have a defective, damaged, or artificial heart valves, take antibiotics when directed by your doctor to reduce the risk of infection. AF can be a complication of such an infection.
  • If you have heart disease or diabetes, you should work with your doctor to control your condition and lower your risk of complications, such as AF.

Check your heart beat twice a year. Because atrial fibrillation increases your risk for stroke, the National Stroke Association recommends that everyone, particularly those age 55 or older or those who have other stroke risk factors, check their heartbeats twice a year. If you notice your heartbeat does not have a regular rhythm, talk to your doctor.

Video Tutorial
  • Atrial Fibrillation from Medline Plus (Scroll down and select "Atrial Fibrillation" under "Diseases and Conditions")This is an excellent animated video tutorial which clearly illustrates cardiac anatomy, the electrical conduction system, and the physiology of atrial fibrillation.
  • Atrial Fibrillation from the National Heart Lung and Blood Institute (scroll down the page to see video)
References
--Written by N Thompson, ARNP in collaboration with M Thompson, MD, Internal Medicine, January 2008

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