Definitions of cardiac implantable electronic devices

Cardiac implantable electronic devices (CIED) include:

• permanent pacemaker devices (PPM)
• implanted cardioverter defibrillators (ICD)
• cardiac resynchronisation therapy devices (CRT).

These devices consist of a pulse generator, which sits in a subcutaneous or submuscular pocket, and one or more leads which connect the pulse generator to the heart. Most leads are inserted percutaneously and are implanted in the endocardium, but some leads are implanted at thoracotomy on the epicardial surface.

Subcutaneous ICDs (S-ICD) have a subcutaneous electrode but do not have an endocardial lead. Leadless pacemakers are implanted directly into the heart without leads. Cardiac loop recorders, also known as implanted cardiac monitors, are implanted in the subcutaneous tissue without leads.