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Defibrillators
When a heart goes into fibrillation, the patient can die unless something is immediately done. A fibrillating heart is not motionless, but it pumps no blood. Instead, each fiber of the heart muscle is contracting independently. There's no coordination, so the rhythm of the heartbeat is impossible. The best way to stop fibrillation is to give the heart a powerful electrical shock. That will override whatever the individual muscle fibers are doing. Each will contract at the instant of the shock, then fall quiet for a period called the refractory interval. There's a decent chance that when they recover from the shock, they'll do so at the same time and pick up the normal activity of the heartbeat. The chaos of fibrillation will have died away during the period of quiet. Applying powerful shocks to the heart is dangerous. They can kill a person - ironically, by setting a normally-beating heart into fibrillation. Therefore, this remedy is only applied to people who are already dead, or at death's door. It's only become reasonably safe in recent years, with the invention of computer-controlled defibrillators that can monitor and analyze the heart's electrocardiogram. They can see if the heart is in fibrillation, and will only apply the shock if it is. Perhaps the earliest intentional use of defibrillation was recommended by Charles Kite, in his Essay on the Recovery of the Apparently Dead (London, 1788). In modern times, defibrillation was brought into medical use by Claude Beck, who used silver paddles to connect the heart of a 14-year-old boy to the 110-volt power line when the boy's heart went into fibrillation after an operation. |
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