Palpitation is an abnormally perceived heartbeat. Although the heart is working nonstop, we seldom notice its beating. If we notice a heartbeat, the heart seems to be working unusually: beating too fast or too slow, skipping a beat or adding an extra one, or pounding and throbbing. These sensations are called palpitations. Heart palpitations can be triggered by stress, exercise, alcohol, caffeine, medication or, more rarely, a medical condition. Although heart palpitations can be worrisome, they're mostly harmless. In rare cases, heart palpitations can be a symptom of diseases like hyperthyroidism or a serious heart condition, such as an irregular heartbeat (arrhythmia) or coronary artery disease . If you experience palpitations very often or if they are accompanied by additional symptoms like dizziness, nausea, shortness of breath, or chest discomfort, you should seek medical advice.