What Is an Arrhythmia?

Beating heart, obtained using a 3T MRI scanner.

An arrhythmia is a change in the rhythm of your heartbeat. When the heart beats too fast, it's called tachycardia. When it beats too slow, it's called bradycardia. An arrhythmia can also mean that your heart beats irregularly (skips a beat or has an extra beat). At some time or another, most people have felt their heart race or skip a beat.

Minor arrhythmias may be caused by excessive alcohol use, smoking, caffeine, stress or exercise. They usually are not a cause for alarm. Arrhythmias that occur more often or cause symptoms may be more serious and need to be discussed with your doctor.