Heart palpitations are an uncomfortable awareness of the heart beating rapidly or irregularly. Palpitations can be caused by stress, fatigue, or overuse of alcohol or stimulants such as caffeine or nicotine, and they usually are not a serious problem.
Heart palpitations can feel like:
If palpitations persist or occur with fainting, near fainting, or lightheadedness, they may be a sign of a heart problem.
WebMD Medical Reference from Healthwise