Arrhythmia refers to any abnormality of the heartbeat, including too slow, too fast, and/or irregular. The most common symptom associated with an arrhythmia is palpitations or an awareness of the heartbeat. A more serious symptom is actual passing out (syncope). Evaluation of an arrhythmia usually includes some form of monitoring device. It is also very important to determine if the heart is structurally normal. How arrhythmias are managed is determined by the status of the heart structures and the extent of the symptoms. The most advanced treatment includes pacemakers and defibrillators but medical therapy is frequently all that is necessary.