The Archimedes' Heart Screw
I vividly remember December 2, 1982. Barney Clark was the first successful recipient of an artificial heart. His crawling life-back-into-death experience lasted a gruesome 112 days. We all tried to be happy at the prospect of a fake heart beating to give us life, but watching Barney, in his wheelchair, dead-in-the-eyes and comatose-of-expression gave us all pause about the meaning of being human. Are we our hearts? Does our mind define us, or are we merely a beating muscle mindlessly flexing and reacting to electric impulses?
Last night, I read an amazing article published in Popular Science detailing an all-new heart replacement called the HeartMate IIs — and its hallmark construction is that it gives recipients no heartbeat or pulse because the device is not a pump, but rather a sophisticated, spinning, Archimedes‘ Screw:
The HeartMate II was an Archimedes’ screw with magnets implanted in the axle and an electric coil in the cylindrical case surrounding it—the saltshaker-shaped device that Cohn had placed in my hands. A charge zipped around the coil, drawing the screw along at 8,000 to 12,000 revolutions per minute. The axle spun on a synthetic-ruby bearing, lubricated by the blood itself. Connected to a portable battery, it let patients live fairly normal lives and was designed to stay in place forever, not merely as a “bridge to transplant.” Patients’ own hearts still worked; the continuous flow of the pump just helped things along.
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