defibrylator

Defibrylator, also known as a defibrillator, is a medical device that delivers an electric shock to the heart in order to restore a normal rhythm after certain life-threatening arrhythmias. External defibrillators are used on the body surface and can be manual (operated by clinicians) or automated (AEDs) that guide by voice prompts and rhythm analysis. Implanted devices, called implantable cardioverter-defibrillators (ICDs), are surgically placed under the skin with leads attached to the heart; they monitor rhythm continuously and deliver shocks or pacing as needed. There are also wearable defibrillator systems used temporarily for people at risk when an implant is not yet indicated.

Defibrillation works by depolarizing a critical portion of the heart, interrupting the chaotic rhythm and allowing the natural pacemaker to resume coordinated beating. Modern external defibrillators use biphasic shocks and deliver energy in the range commonly from 120 to 360 joules, depending on the device and rhythm. AEDs are designed for use by lay responders with audible prompts, whereas manual external defibrillators require trained personnel.

Defibrillation is a key component of emergency treatment for cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia; it is not effective in all arrests and is usually combined with high-quality CPR and advanced life support. Safety considerations include proper pad placement, avoiding electrode contact with implanted devices, and following device-specific instructions.

The development of defibrillation began in the mid-20th century, with rapid advancement in device design and the spread of AEDs in public and hospital settings by the late 20th and early 21st centuries.