Cardiovascular Disease: Cardioverter-Defibrillators and Left Ventricular Assist Devices.

Sudden cardiac death (SCD) is an abrupt and unexpected death presumed to be due to cardiac causes. The primary etiologic mechanism is cardiac arrest due to an arrhythmia. Cardioverter-defibrillators detect abnormal arrhythmia and abort the rhythm with an electrical shock. Wearable cardioverter-defibrillators are devices in which the leads contact the chest on a vest worn by the patient. Wearable devices are for patients at temporary risk of SCD, when comorbidities prohibit placement of an implantable cardioverter-defibrillator (ICD), or as a bridge to ICD placement or heart transplantation. ICDs are indicated for patients who have survived sudden cardiac arrest (secondary prevention) and patients with conditions that put them at increased risk of SCD (primary prevention). Left ventricular assist devices (LVADs) are surgically implanted on the exterior of the heart. They draw blood out of the heart through a cannula placed through the wall of the left ventricle and pump it, via a conduit sewn into the aorta, into the circulation. LVADs are indicated for patients with ionotropic, drug-dependent, end-stage heart failure as a bridge to transplantation or as a final therapy if transplantation is not possible.