Automatic Internal Cardiac Defibrillator

Excerpt

The automated internal cardiac defibrillator or shock box is the common name given to the Implantable Cardioverter Defibrillator (ICD).

ICD is a state-of-the-art device that treats arrhythmias specifically those of ventricular origin like ventricular tachycardia and fibrillation. It has become the first line of defense in patients who are at high risk for sudden cardiac death (SCD) and has shown consistent survival benefit in cardiac arrest survivors (SCA), in patients with Heart failure and severe systolic dysfunction (left ventricular ejection fraction-LVEF less than or equal to 35%) as well as in patients with hypertrophic cardiomyopathy (HCM).

ICD is essentially a pacemaker with the ability to recognize abnormally fast cardiac rhythm and provide an immediate treatment which can be in the form of overdrive pacing called anti-tachycardia pacing (ATP) or shock therapy which could be synchronized or asynchronized, depending on the recognized rhythm and the pre-programmed rhythm detection algorithm. It comes in three systems, a single lead or single chamber device, a dual lead or a dual-chamber device, and one that is coupled with cardiac resynchronization therapy (CRT-D) that is essentially a bi-ventricular device with leads in the right atrium (RA), Right ventricle (RV) and coronary sinus (CS) lead. Due to its proximity, CS lead is also called the LV lead.

In 2012, the US Food and Drug Administration (FDA) approved the sub-cutaneous device (S-ICD) which used sub-cutaneous leads rather than intra-cardiac leads. Recently, wearable defibrillators (WCD) have also been introduced for short-term usage.