Lipp Vis Nursing ChaptLWBK1630_C02_p013-068

Chapter 2 • Cardiovascular Care  55

Implantable Cardioverter Defibrillators A Look at an ICD

An ICD typically consists of a programmable pulse generator and an electrode. Most new ICDs can act as both pacemakers and defibrillator. The subcutaneous implantable cardioverter defibrillator (S-ICD), which is being implanted throughout the world, was approved for use in the United States in September of 2012. The S-ICD can be implanted without the use of fluoroscopy by using anatomic landmarks to guide proper positioning.

Left subclavian access line

Leadwire

Pulse generator

Types of ICD Therapies VF is a common cause of sudden cardiac death (SCD) and is sometimes preceded by monomorphic or polymorphic ventricular tachycardia (VT). While cardiopulmonary resuscitation, including chest compressions and assisted ventilation, can provide temporary circulatory support for the patient with cardiac arrest, the only effective approach for terminating VF is electrical defibrillation. Development of the ICD was first implanted in humans in the 80s, which lead to the success and survival of patients with VF/VT.

Therapy

What It Does

Antitachycardia pacing

A series of small, rapid, electrical pacing pulses are used to terminate ventricular tachycardia (VT) and return the heart to its normal rhythm.

Cardioversion

A low- or high-energy shock is timed to the R wave to terminate VT and return the heart to its normal rhythm.

Defibrillation

A high-energy shock to terminate ventricular fibrillation and return the heart to its normal rhythm.

Bradycardia pacing

Electrical pacing pulses are used when the heart’s natural electrical signals are too slow. Most ICD systems can pace one chamber (VVI pacing) of the heart at a preset rate. Some systems sense and pace both chambers (DDD pacing).