Some people have an irregular heartbeat that causes them to be weak, tired or dizzy. This irregular heartbeat can cause blood clots to form in the heart if left untreated, and in turn can cause those clots to travel into the brain and cause a stroke. After medicine is given by an anesthesiologist, the chest is prepared with electrodes and an electrical shock is delivered. This is successful most of the time and the patient does not remember the shock. The goal is to help the heartbeat return to normal.