What Is Atrial Fibrillation?

At the core of every healthy body is a strong, steady heartbeat. Atrial fibrillation is a condition that disrupts this rhythm. A glitch in the heart's electrical system makes the upper chambers (the atria) quiver or fibrillate. This causes the lower chambers (the ventricles) to beat irregularly. Atrial fibrillation can be dangerous because it raises the risk of stroke and heart failure.

Warning Sign: Uneven Pulse

In many people, atrial fibrillation does not cause obvious warning signs. When symptoms do occur, they often include:

• An uneven pulse
• A racing or pounding heart
• A feeling that the heart is fluttering
• Chest pain

Normal Heart Rhythm vs. Fibrillation

Normally, electrical signals from the sinus (SA) node start each heartbeat. The AV node relays the signals, so the four chambers pump blood in perfect rhythm. In atrial fibrillation, abnormal signals fire from many areas within the atria. These chaotic signals make the top chambers quiver rapidly. Too many signals are passed through to the ventricles. The result can be irregular contractions that can cause a fast, irregular heart rate (100-175 beats per minute). The normal range is 60-100 beats per minute.

Warning Sign: Dizziness

An erratic heartbeat can take a toll on the body, leading to problems such as:

• Dizziness
• Breathlessness
• Weakness and fatigue
• Fainting

Atrial Fibrillation and Stroke

If the heart isn't contracting as it should, blood can pool and may form a clot. This clot can travel through the bloodstream to the brain, causing a stroke. Among people with healthy heart valves, those with atrial fibrillation are six times more likely to have a stroke than those without the condition. This risk is even greater in people with damaged heart valves.

When to Seek Emergency Care

Atrial fibrillation is not always an emergency, but you should call 911 if you have any of these symptoms:

• Severe chest pain
• Uneven pulse and feeling faint
• Signs of a stroke, such as numbness or slurred speech

What Causes Atrial Fibrillation?

The most common triggers are conditions that strain the heart, including:

• High blood pressure
• Coronary artery disease and heart attacks
• Heart failure
• Problems with heart valves

In some cases, atrial fibrillation may stem from thyroid disorders or serious infections, such as pneumonia.

Risk Factors You Can't Control

Besides heart conditions, there are several factors that raise your risk of developing atrial fibrillation. Some of these are outside of your control:

• Being male and white
• Being over age 60
• A family history of atrial fibrillation

Risk Factors You Can Control

Your lifestyle and habits can also influence your risk. Atrial fibrillation has been linked to:

• Obesity
• Lung disease
• Certain prescription drugs, such as albuterol
• Stimulants, including some illegal drugs, and excess use of nicotine or caffeine
• Drinking excessive amounts of alcohol

Heart Surgery Can Be a Trigger

Having a coronary artery bypass or other type of heart surgery can trigger atrial fibrillation. In people older than 65, any type of surgery can be a trigger. When atrial fibrillation occurs after surgery, it increases the risk of other complications. Fortunately, this type of atrial fibrillation is usually short-lived.

Lone Atrial Fibrillation

Sometimes the atria begin to fibrillate with no known trigger. This is called lone atrial fibrillation, and it's more common in people younger than 65. The heart usually returns to its normal rhythm on its own. But treatment may be needed if a rapid heartbeat causes troubling symptoms. In people older than 75, doctors recommend treating lone atrial fibrillation to reduce the risk of stroke.

Diagnosing Atrial Fibrillation: EKG

The surest way to detect atrial fibrillation is with an electrocardiogram (EKG.) This painless test records the electrical activity of your heart and reveals abnormalities in the heart's rhythm. The test can be done in a doctor's office, or your doctor may ask you to wear a device that records your heart's activity continuously for 24 hours or longer.

Other Tests for Atrial Fibrillation

If an EKG shows that you have atrial fibrillation, your doctor may order additional tests to learn more about your heart. An echocardiogram or ultrasound of the heart can show whether there is any valve damage or signs of heart failure. A stress test can show how well your heart is performing. Your doctor may also order tests to look for conditions that may have triggered your atrial fibrillation.

The Course of Atrial Fibrillation

When people first develop atrial fibrillation, it may come and go. The irregular heart rhythm may last anywhere from a few seconds to a few weeks before returning to normal. Eventually, atrial fibrillation may become persistent, meaning that the heart rhythm remains irregular. If the trigger is identified as a thyroid problem, pneumonia, or other treatable illness, atrial fibrillation usually goes away once the cause is treated.

Treatment: Cardioversion

Under certain circumstances, your doctor may try to restore a normal heart rhythm with an electrical shock or medication. This procedure is known as cardioversion. If you've been having atrial fibrillation for more than 48 hours, cardioversion could increase your risk of stroke. In that case, you may need to take blood-thinning medication for several weeks before your doctor tries the procedure, as well as after cardioversion.

Treatment: Medication

If your symptoms are mild, or if atrial fibrillation comes back after cardioversion, your doctor may recommend managing the condition with medications. Rhythm-control medicines help regulate your heart rhythm. Rate-control medicines keep the heart from beating too fast. The anticlotting medication warfarin or daily aspirin can help reduce the risk of stroke.

Treatment: Ablation

If cardioversion and medications fail to control the symptoms of atrial fibrillation, radiofrequency ablation is an option. This procedure uses radiofrequency energy to destroy the heart tissue responsible for abnormal electrical signals. Although it does not require open heart surgery, ablation has some risks. It is only recommended for people who have serious symptoms despite trying other treatments.

Treatment: Surgery

A type of surgery called the maze procedure can cure atrial fibrillation. Doctors make a pattern of small cuts to create scar tissue in the atria. The scar tissue blocks the abnormal electrical impulses that cause atrial fibrillation. This procedure is usually done during open heart surgery, but some medical centers are now offering a minimally invasive alternative.

Treatment: Pacemaker

A pacemaker is a small, battery-powered device that regulates your heart rate by firing off electrical signals. For example, it can be helpful for people who have a very slow heart rate and relieve symptoms such as fatigue and shortness of breath. A pacemaker is also required after certain types of ablation. Implanting a pacemaker in the chest is considered minor surgery and usually takes about an hour.

Atrial Fibrillation: Outlook

Many people find that atrial fibrillation has no impact on their daily lives. Others must try a variety of treatments to manage troubling symptoms, such as weakness, shortness of breath, or fainting. In either case, it's critical that people with atrial fibrillation take precautions to reduce the risk of stroke.

Preventing Atrial Fibrillation

The same healthy habits that protect against heart disease will protect against atrial fibrillation:

• Eat a nutritious diet that includes fish.
• Exercise regularly.
• Control your blood pressure.
• Avoid smoking.

Check Your Pulse Regularly

Atrial fibrillation can lead to a stroke or other serious problem before it causes noticeable symptoms. To identify an irregular heartbeat early, the National Stroke Association recommends checking your pulse once a month -- especially if you are over 55 or have risk factors for stroke. If the rhythm seems unsteady or you have any concerns, contact your health care professional.

More Reading on Heart Conditions

• Atrial Fibrillation
• Heart Rhythm Disorders (Abnormal Heart Rhythms)
• A Visual Guide to Heart Disease
• Heart Disease (Coronary Artery Disease)
• 15 Tips for Avoiding Heart Disease
• 25 Foods to Protect Your Cardiovascular System