Electrophysiological studies used to detect cardiac abnormalities observing the electrical activity of the heart. It is performed by inserting a catheter in the area (usually the neck or groin) through which electrodes are passed into the body, directing them to the heart by fluoroscopy. Thus it may be permanently analyze the activity of the heart muscle and recognize the causes of heart failure of the patient. This therapeutic electrophysiology study may involve discomfort in the puncture site and even more serious risks, such as palpitations. If they occur, should make an electric shock in the area to redirect the problem and continue the process of study.