Atrial Fibrillation & Flutter

Atrial Fibrillation

Atrial Fibrillation (also called AF or A Fib) is a common heart rhythm disorder caused by a problem in the conduction of electrical impulses in the upper chambers, or atria, of the heart. A Fib and other rapid heartbeats that arise in the atria, or in the juncture between the atria and the lower chambers (ventricles) are called "supraventricular tachycardias."

More than 2 million people in the U.S. have A Fib, and about 160,000 new cases are diagnosed each year. A Fib is uncommon among young people, although it can occur in people of any age. The likelihood of developing the condition, however, increases as we get older. After age 65, between 3 percent and 5 percent of people have atrial fibrillation. Approximately 9 percent of people who are age 80 or older have the condition.

What Causes A Fib?

In A Fib, the electrical signals that coordinate the muscle of the upper chambers (atria) of the heart become rapid and disorganized, typically causing the atria to beat faster than 300 beats per minute. (The normal rate when the heart is at rest is about 60 to 80 beats per minute). When this happens, the atria may contract poorly and no longer effectively force blood into the lower chambers (ventricles). As a result, the flow of blood to the body may be reduced. Atrial fibrillation may occur from time-to-time, or it may be a permanent condition.

IF TREATED APPROPRIATELY, ATRIAL FIBRILLATION AND ATRIAL FLUTTER SELDOM CAUSE SERIOUS OR LIFE-THREATENING PROBLEMS.

Types of Atrial Fibrillation

	An electrocardiogram (ECG) is a printout of the heart's electrical activity. This ECG is of a patient with atrial fibrillation.

Paroxysmal A Fib. Episodes of A Fib that end spontaneously are called paroxysmal A Fib. This type of atrial fibrillation usually comes on suddenly, and its symptoms can range from mild to severe. The irregular heart rhythm may last for a few seconds, minutes, hours or longer before the heart resumes a normal rhythm on its own.

Persistent A Fib. With this condition, the irregular heart rhythm continues indefinitely unless it is treated.

Permanent A Fib. In this situation, normal rhythm cannot be restored.

Health Risks

In younger people who have no other disease that affects the heart, atrial fibrillation or flutter usually is not considered serious. Some people with atrial fibrillation, however, are at increased risk of stroke, heart failure or heart muscle disease.

Sometimes, A Fib can damage heart muscle and alter the normal electrical signals to the heart. This may change the patterns of contraction and relaxation of heart muscle. This is known as electrical remodeling.

According to the Framingham Heart Study, people with A Fib or flutter have a 3 to 5 times greater risk of stroke, especially individuals who are older than 65, have already had a stroke, or have high blood pressure, diabetes or congestive heart failure.

When a blood clot lodges in the arteries to the brain, blood supply is cut off and the result is stroke.

An Increased Risk of Stroke

During an episode of A Fib or AFL, the heart muscle does not contract normally to force open the heart valves that pass blood from the atrium to the ventricle. The valve opens passively, but some blood may not enter the ventricle as it should. Instead, it pools in parts of the atrium, increasing the risk that clots will form in the stagnant blood.

Even small blood clots can cause problems if they leave the heart and are released into the general circulation. They may clog arteries in the body and disrupt the blood supply to vital organs. A stroke occurs when a clot lodges in the arteries that supply blood to the brain.