Published: Nov 6, 2022 by Bertland Hope

How does a Defibrillator work?

As the name suggests, the defibrillator is a device that stops fibrillation – the condition where the heart starts to beat erratically, usually during cardiac arrest.

There are several types of defibrillators, biphasic, monophasic and automated external defibrillators (AEDs). They can also be automatic internal defibrillators, with or without a pacemaker (AICD).

Cardiac arrest occurs when the electrical rhythm in a person’s heart causes it to stop beating at a normal rhythm. This results in an irregular beat called arrhythmia which prevents the heart from moving oxygenated blood around the body properly.

When blood flow to the brain and other vital organs are stopped the person will suddenly collapse and become unresponsive. You won’t be able to feel their pulse or detect breathing. A person in cardiac arrest will have minutes to survive and using a defibrillator is the only way to help them recover and get their heart beating at a normal rhythm (sinus rhythm) again.

A defibrillator works by de-polarising the cardiac muscle with a short electrical shock. This allows the cells in the heart to recharge at the same time, reestablishing the sinus rhythm in the process.