A pacemaker is a small electronic device that helps regulate slow electrical problems in the heart. The pacemaker is usually implanted in the chest, below the collarbone. A doctor may recommend this device to keep the heartbeat from slowing down to a dangerously low rate. There may be other reasons for a doctor to recommend pacemaker insertion.
A biventricular pacemaker is used to make ventricles contract at the same time, increasing the amount of blood pumped by the heart. This treatment is called cardiac resynchronization therapy (CRT).