Palpitations are an abnormality of the heartbeat that ranges from often unnoticed skipped beats or accelerated heart rate to very noticeable changes accompanied by dizziness or difficulty breathing. Palpitations are common and occur in most individuals with healthy hearts. Palpitations without underlying heart disease are generally considered benign. However, heart palpitations can be a symptom of a serious illness such as coronary heart disease, asthma, or emphysema. A holter monitor is used to see whether your symptoms of palpitations correlate with a significant rhythm disturbance.