The most commonly occurring abnormal heart rhythm is atrial fibrillation. It occurs when the atria (the upper two chambers of the heart) quiver instead of beating strongly. Atrial fibrillation can cause the atria to beat as much as four hundred beats per minute.
- Atrial fibrillation occurs in about three to five percent of those over the age of sixty-five.
- About 2.2 million Americans have atrial fibrillation.
- Symptoms of atrial fibrillation may include heart palpitations, lightheadedness, shortness of breath, fainting, fatigue, and rapid or irregular pulse.