Arrhythmia is an abnormal heart rhythm. The rhythmic succession of heartbeat in an adult at rest is between 75 and 90 beats per minute, so when these are increased significantly beats talking about sinus tachycardia, while failing if the heartbeat is slow it down, is is sinus bradycardia. In tachycardia, the heart experiences a substantial acceleration fruit of a tremendous physical effort or in response to organizational needs. When the alteration does not occur but the number of heartbeats in the frequency in which they appear speaking of cardiac arrhythmia. In atrial fibrillation, the beats have increased and unbalanced; On the contrary, where there will be a lock deficit beats can result in clinically palpitations or blackouts.