What Is A Defibrillator And How Does It Work?

Dr. William O'Neill answers the question: 'What Is A Defibrillator?'

ByWilliam O'Neill, M.D., Executive Dean for Clinical Affairs, University of Miami Miller School of Medicine
November 20, 2008, 10:31 AM

— -- Question: What is a defibrillator and how does it work?

Answer :A defibrillator is an electrical device that provides a shock to the heart when there is a life-threatening arrhythmia present. The arrhythmia that we worry about is called ventricular fibrillation. This is a very rapid erratic beating of the heart. Multiple parts of pacemakers in the heart starts sort of beating erratically and the heart can't rhythmically contract. And what the defibrillator does, it provides shock that basically shocks the heart to stop so that it can start rhythmically contracting again.

We've seen in the movies and on TV where they put these big paddles on the chest and shock the chest, that's an external defibrillator. We have internal defibrillators. these are devices that are again pacemakers that can be put under the chest wall, wires are put inside the heart, and rather than having a big shock outside the chest, there's actually a good size shock that goes inside the heart muscle again that stops the heart from this life-threatening rhythm and shocks the heart to get it to start beating rhythmically and regularly again. It's an incredibly life-saving tool that is literally saving thousands of lives a year in the United States.

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