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This is Scientific American 60 Second Science.

I'm Christopher Int Tagyatta.

That beeping sound is the normal beating of a heart.

But here's what the same heart sounds like during a bout of ventricular tachycardia or VT.

The racing beats are caused by an electrical short circuit in the muscle and in a moment

a defibrillator is going to zap the heart to return it to a slow and steady pace.

The root cause of VT?

So the villain inside the heart is almost always a scar from a prior injury.

Philip Kukulich, a cardiac electrophysiologist at Washington University in St.

Louis.

Most commonly that's a prior heart attack, but sometimes it's leftover scar from an infection that somebody might

have or an inflammatory disease that somebody might have.

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