Confining the Shock to the Heart Muscle (IMAGE) Washington University in St. Louis Caption The major innovation of the recent work is an electrotherapy that greatly decreases the energy needed to shock a heart back into rhythm. But moving the electrodes also helps. The standard implantable defibrillator consists of an electrode in the right ventricle and a “can” implanted in the patient’s chest. Placing the second electrode within the coronary sinus so that the shock is confined to the heart muscle means that less energy is needed and the shock is less painful. Credit JACCS Usage Restrictions Credit required License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.