Atrial fibrillation is a term that defines both the location and the nature of one particular type of arrhythmia. The abnormal rhythm originates in the atria and it has a fibrillating nature. Fibrillation is characterized by rapid, chaotic quivering. In atrial fibrillation, the rhythm is circular and unorganized, and the rhythm in the atria increases to 300 to 600 beats per minute -- as much as six times faster than a normal heartbeat.
If left untreated, the rapid, chaotic beating of atrial fibrillation can weaken the heart muscle. Over time, the heart stretches, grows thicker, and has increasing difficulty in contracting and pumping blood properly.
This condition, known as heart failure, is serious and potentially life-threatening. People with atrial fibrillation are also at increased risk of stroke. Because the heart's chambers are not efficiently emptied, blood can pool and sometimes clot. If a clot in the atria breaks loose and travels to the arteries in the brain, a stroke can result. About 15 percent of the 700,000 strokes that occur in the United States each year -- approximately 105,000 -- occur in people with atrial fibrillation.
Atrial fibrillation is associated with high blood pressure, hardening of the arteries, heart failure, coronary artery disease, and other types of heart disease, such as valve disease, pericarditis (inflammation of the heart membrane), congenital heart defects, and with chronic lung diseases. It may also be caused by factors unrelated to the heart, such as diabetes and thyroid disease, certain medications, diet, stress, and environmental toxins. While many of the atrial fibrillation risk factors can be controlled by lifestyle changes, aging impacts everyone despite our best efforts to slow its effects. If you are 50 years old or younger, your risk for atrial fibrillation is one in every 100 people, but by the time you are over 80 years, your risk increases tenfold to one in every 10 people.
For more information on atrial fibrillation and other heart topics, check out the links on the next page.