What is the term for heartbeats that occur outside the normal rhythm?

Arrhythmia means your heartbeat is irregular. It doesn't necessarily mean your heart is beating too fast or too slow. It just means it's out of its normal rhythm.It may feel like your heart skipped a beat, added a beat, is "fluttering," or is beating too fast (which doctors call tachycardia) or too slow (called bradycardia). Or, you might not notice anything, since some arrhythmias are silent. Arrhythmias can be an emergency, or they may be harmless.