What is a defibrillator used for?

You have probably seen an automated external defibrillator (AED) on the wall at a gym or where you work, or you may even have a friend or relative with an implantable defibrillator (ICD).  Regardless of how, there is a good chance you have heard of a defibrillator before, but you may still wonder what exactly a defibrillator is used for.

A defibrillator is the single most important machine needed in cases of sudden cardiac arrest, so to understand what a defibrillator is used for you first have to understand what sudden cardiac arrest (SCA) is.

First, medically defined, SCA is triggered by an electrical malfunction in the heart that causes an irregular heartbeat, also called arrhythmia.  In other words, the heart has a steady rhythm that speeds up or slows down depending on the demands put on it.  SCA is when, from an electrical malfunction called ventricular fibrillation, the heart loses that natural rhythm.  When the heart loses its normal rhythm it is unable to generate blood pressure and without that, the brain soon shuts down.  In fact, it is so soon that a typical untreated victim’s chance of survival drops by 10% every minute and by ten minutes will die.

A defibrillator is used to provide a shock to the heart that literally defibrillates the ventricular fibrillation; put simply, it stops the heart.  Once the heart is stopped, the hope is that without the confusing electrical signals the heart will naturally start to beat again at its normal rhythm.  Another way of thinking of a defibrillator is by comparing it to a computer.  Anyone familiar with a computer knows that it has many electrical signals going through it.  Often, when something goes wrong it’s because some of the signals get mixed up and unless the damage is more permanent, it can be restored simply by restarting the computer.  Basically, a defibrillator is like the restart button.  Unless the heart’s damage is more permanent, the shock from the defibrillator shuts down the heart and then the heart naturally restarts.

SCA is the leading cause of death in the United States.  It is responsible for an estimated, 325,000 deaths every year.  Another estimate shows that 95% of SCA victims die before they receive any kind of help.  Treatment with a defibrillator gives a victim the best chance of surviving that.