Cardiac defibrillation and resynchronization therapies: principles, therapies, and management implications

Patients with heart failure remain at high risk for sudden cardiac death (SCD) and death due to heart failure progression, despite the incorporation of pharmacologic agents into clinical practice that have been shown to decrease mortality in clinical trials. Most patients experience SCD as their first dysrrhythmic event. The implantable cardioverter defibrillator (ICD) effectively terminates ventricular tachycardia/fibrillation (VT/VF) aborting SCD. Cardiac resynchronization therapy (CRT) complements pharmacologic therapy improving cardiac performance, quality of life, functional status, and exercise capacity in patients with systolic dysfunction despite optimal medical therapy who have a prolonged QRS duration; furthermore, it decreases mortality when compared with optimal medical therapy alone. Implantation of a combination CRT and ICD device, a CRT-D, reduces mortality by aborting SCD and providing the functional benefits of CRT. This article discusses the evolution of CRT-D therapy, the mechanism of operation of a CRT-D device, and nursing implications.