A pacemaker is a device doctors implant to treat arrhythmia. These may be temporary or permanent. CRT involves implanting a specific type of permanent pacemaker to help your heart’s lower chambers (ventricles) beat together.
A CRT (or biventricular) pacemaker has three leads that control both the right and left ventricles. Typical pacemakers can have only one or two leads and are only in one side of the heart.