A pacemaker for heart failure, used for cardiac resynchronization therapy (CRT), sends electrical pulses to the heart to keep the lower chambers (the ventricles) pumping together. This type of pacemaker is also called a biventricular pacemaker. The pacemaker can help reduce the symptoms of heart failure.

A doctor places the pacemaker in the chest. The pacemaker has three wires, or leads, that connect to the heart. One lead is in the right atrium (upper chamber). A second lead is in the right ventricle. The third lead is in a vein, called the coronary sinus branch vessel, which is on the outside of the left ventricle.