Feeling as if your heart has "skipped a beat" is a type of arrhythmia, or irregular heartbeat. Although many types of arrhythmia can be serious or fatal, "skipping a beat" is generally harmless.
Your heart is not actually "skipping" a beat--rather, a beat comes early, and there is a pause followed by a more forceful beat, which is the beat you feel.
There are two types of skipped beats, called premature contractions. Premature atrial contractions or PACs are in the upper chambers of the heart, called the atria. Premature ventricular contractions or PVCs are in the lower chambers of the heart, called ventricles.
Who Gets Them
Almost all people get premature contractions at some point, though they are especially common in healthy children and teenagers.
Doctors usually don't know the cause of premature contractions. If they don't happen regularly (more than once a week), they are not usually cause for concern. However, they can be caused by injury to the heart. So more tests might be in order, especially if premature contractions persist.
Premature contractions generally disappear on their own, with no cause found. If doctors determine why they are happening--trauma to the heart or other cause--then treatment can be planned.