Cardiac Rhythm Management Devices: An Overview

Cardiac rhythm management (CRM) devices include pacemakers, implantable cardioverter-defibrillators (ICDs), cardiac resynchronization therapy defibrillators (CRT-Ds), and cardiac resynchronization therapy pacemakers (CRT-Ps). They are used to help treat cardiac conditions stemming from problems with the heart's electrical conduction system, which can result in serious, often life-threatening arrhythmias. CRM devices are implanted in patients to help restore and maintain the heart's electrical function, and can mean the difference between life and death for many patients.

Implantable CRM devices usually have three components: a pulse generator, leads, and a programmer. The conductive electrode leads connect to the hermetically sealed generator in an area called the header.

The pulse generator contains the circuitry that monitors the electrical activity of the patient's heart and uses algorithms to determine when to deliver an electrical impulse through the leads to pace or shock the heart muscle. It also houses the battery.

Leads are long (45 to 70 cm) insulated wires that run from the header of the pulse generator through the patient's venous circulation and attach to the heart muscle. They perform...