- Cardiac pacemaker is composed of two main elements: (a) a pulse generator and (b) lead wires with electrodes for contact with the endocardium or myocardium.
- The pacemaker generator (battery pack and control unit) is most commonly placed in the infraclavicular area.
- Single chamber cardiac pacers: lead terminates in right ventricle.
- Dual chamber cardiac pacers: leads terminate in right atrial appendage and right ventricular apex.
- Biventricular pacers: Left ventricular epicardial leads are used. The leads go directly to the surface of the left ventricle, and they are usually associated with typical pacing electrodes in the right atrial appendage and right ventricular apex. In other cases, the left ventricular pacing electrodes are introduced through the coronary sinus and wedged into a left ventricular cardiac vein.
- The automatic implantable cardioverter defibrillator (AICD or ICD) is a common cardiac device designed for both patient monitoring and therapy in case of ventricular tachycardia or fibrillation.
- AICDs consist of various combinations of sensing and shocking electrodes. They are frequently combined with a pacemaker as a bundled system for the patient, treating both the patient’s established arrhythmia and also acting as a fail-safe system should ventricular fibrillation or ventricular tachycardia occur.
 Imaging Findings
Patient #1: Tri-lead cardiac pacer
 See Also
 External Links
- Tim B. Hunter, Mihra S. Taljanovic, Pei H. Tsau, William G. Berger, and James R. Standen. Medical Devices of the Chest. RadioGraphics 2004 24: 1725-1746.