Palpitations are the unpleasant sensations of irregular and/or forceful beating of the heart in the chest. This symptom can be caused by a change in the rate or rhythm, or by an increase in the force of the contraction of the heart muscle. In some patients with palpitations, no heart disease or abnormal heart rhythms can be found. In others, palpitations result from abnormal heart rhythms called arrhythmias. Arrhythmias are heartbeats that are too slow, too rapid, irregular, or too early.