An arrhythmia is an abnormal heartbeat rhythm. Arrhythmias happen when the heart beats too fast, too slow or beats irregularly, such as atrial fibrillation, the most common arrhythmia in the U.S.
Most arrhythmias are harmless. It’s common to feel your heart “skip” a beat or speed up when you’re afraid, excited or exercising. Too much caffeine and certain medications also can cause heart palpitations.
When irregular heartbeats are frequent or chronic, they can be serious — and sometimes life threatening. If your heart can’t pump enough blood to the body, it can damage the brain and other organs. Arrhythmias can lead to symptoms like shortness of breath or chest pain. They’re most commonly caused by heart disease, abnormal heart valve function or heart failure.
If your heart beats too fast, it’s called tachycardia. If your heart beats too slow, it’s called bradycardia. Common arrhythmias include atrial fibrillation, ventrical fibrillation, AV node re-entry tachycardia and Wolffe-Parkinson-White Syndrome.