Atrial fibrillation/flutter is a heart rhythm disorder (arrhythmia). It usually involves a rapid heart rate that is not regular.

Causes

Arrhythmias are caused by problems with the heart's normal electrical conduction system.

Normally, the four chambers of the heart (two atria and two ventricles) contract (squeeze) in an orderly way. When this happens, your heart is able to pump the blood your body needs without working any harder than it needs to.

The electrial impulse that signals your heart to contract begins in the sinoatrial node (also called the sinus node or SA node). This node is your heart's natural pacemaker.

• The signal leaves the SA node and travels through the two upper chambers (atria).
• Then the signal passes through another node (the AV node), and finally, through the lower chambers (ventricles).

In atrial fibrillation, the electrical impulse of the heart is not regular. The atria are contracting very quickly and not in a regular pattern. This makes the ventricles beat abnormally, leading to an irregular (and usually fast) pulse. As a result, the heart may be working harder and may no longer be able to pump enough blood.

In atrial flutter, the ventricles may beat very fast, but in a regular pattern.

If the atrial fibrillation/flutter is part of a condition called sick sinus syndrome, the sinus node may not work properly. The heart rate may alternate between slow and fast. As a result, there may not be enough blood to meet the needs of the body.

Atrial fibrillation can affect both men and women. It becomes more common with increasing age.

Causes of atrial fibrillation include:

• Alcohol use (especially binge drinking)
• Congestive heart failure
• Coronary artery disease (especially after a heart attack or coronary artery bypass surgery)
• Heart surgery
• High blood pressure (hypertension)
• Hypertrophic cardiomyopathy
• Medications
• Overactive thyroid gland (hyperthyroidism)
• Pericarditis
• Valvular heart disease (especially mitral stenosis and mitral regurgitation)

Symptoms

You may not be aware that your heart is not beating in a normal pattern, especially if it has been occurring for some time.

Symptoms may include:

• Pulse that feels rapid, racing, pounding, fluttering, or too slow
• Pulse that feels regular or irregular
• Sensation of feeling the heart beat (palpitations)
• Shortness of breath
• Confusion
• Dizziness, light-headedness
• Fainting
• Fatigue

Note: Symptoms may begin or stop suddenly. This is because atrial fibrillation may stop or start on its own.

Exams and Tests

The health care provider may hear a fast heartbeat while listening to the heart with a stethoscope. The pulse may feel rapid, irregular, or both. The normal heart rate is 60 - 100, but in atrial fibrillation/flutter the heart rate may be 100 - 175. Blood pressure may be normal or low.

An ECG shows atrial fibrillation or atrial flutter. Continuous ambulatory cardiac monitoring -- Holter monitor (24 hour test) -- may be necessary because the condition often occurs at some times but not others (sporadic).

Tests to find underlying heart diseases may include:

• Coronary angiography
• Echocardiogram
• Electrophysiologic study (EPS)
• Exercise treadmill ECG
• Nuclear imaging tests

Treatment

In certain cases, atrial fibrillation may need emergency treatment to get the heart back into normal rhythm. This treatment may involve electrical cardioversion or intravenous (IV) drugs such as dofetilide, amiodarone, or ibutilide. Drugs are typically needed to keep the pulse from being too fast.

Daily medications taken by mouth are used in two different ways:

• To slow the irregular heartbeat. These medications may include beta-blockers, calcium channel blockers, and digitalis.
• To keep atrial fibrillation from coming back. These medications may work well in many people, but they can have serious side effects. Many patients may go back to atrial fibrillation even while taking these medications.

Blood thinners, such as heparin and warfarin (Coumadin) reduce the risk of a blood clot traveling in the body (such as a stroke). Because these drugs increase the chance of bleeding, not everyone will use them. Antiplatelet drugs such as aspirin or clopidogrel may also be prescribed. Your doctor will consider your age and other medical problems to decide which drug is best.

A procedure called radiofrequency ablation can be used to destroy areas in your heart that may be causing your heart rhythm problems. Cardiac ablation procedures are done in a hospital laboratory by specially trained staff. Reasons why ablation may be done include:

• When medicines are not controlling the symptoms, or are causing side effects
• When the condition will become dangerous if not treated
• As a possible cure for some patients with atrial flutter

Some patients may need the radiofrequency ablation done directly on an area of the heart called the AV junction. Ablation of the AV junction leads to complete heart block. This condition needs to be treated with a permanent pacemaker.

Outlook (Prognosis)

The disorder is usually controllable with treatment. Many people with atrial fibrillation do very well.

Atrial fibrillation tends to become a chronic condition, however. It may come back even wtih treatment.

Possible Complications

• Fainting (syncope), if atrial fibrillation and atrial flutter cause the pulse to be too quick or slow
• Heart failure
• Stroke, if clots break off and travel to the brain (drugs that thin the blood such as heparin and warfarin can reduce the risk)

When to Contact a Medical Professional

Call your health care provider if you have symptoms of atrial fibrillation or flutter.

Prevention

Follow the health care provider's recommendations for treating underlying disorders. Avoid binge drinking.

Alternative Names

Auricular fibrillation; A-fib