A physiologist at the University of Minnesota had recommended that the
heart team stimulate contraction of the child’s heart with their lab
machine, the Grass Stimulator, which produces a small-voltage electrical
charge. In physiology labs and introductory classes around the globe (to
this day), scientists use the stimulator to send a small pulse of electricity
through the wires into a test subject. To make the leg of a frog jump, a
physiologist pokes tiny wires into the leg muscles, connects them to a
Grass Stimulator, and adjusts the voltage and timing to make the muscles
contract. After preliminary tests on dogs, Lillehei’s team was hopeful that
the stimulator could work on a child suffering complete heart block.
When an open-heart child suffered complete heart block in 1957, Dr.
Lillehei and his team inserted an insulated wire into the heart muscle of
the patient, connected it to the stimulator, and realized—in triumph—that
he could control the beating of the heart. By turning the dial, Lillehei was
able to increase the beating of the heart, a contrivance that William
Harvey would have savored. While this represented real achievement, it is
astonishing to consider the real-world logistics of applying the life-
supporting electrical current. The Grass Stimulator was the size of a
microwave oven, requiring an AC outlet and extension cord. In fact, to
venture from the operating room to the recovery room, a one-hundred-foot
extension cord was required to keep the equipment plugged in and the
patient alive. Imagine the cardiac team, venturing from the open-heart
room with a small child on a postoperative gurney, the anesthesiologist
monitoring the breathing of the unconscious patient (still intubated), and
the surgeons feeding out orange extension cord down the hallway to keep
the heart pacing at a life-sustaining rate.
The AC-powered cardiac stimulator was a lifeline for those patients
who had suffered complete heart block, but a disaster occurred on October
31, 1957, when a municipal power outage in Minneapolis led to loss of
electrical power to the patient ward rooms, resulting in the death of a
young patient. The loss of the patient must have been crushing to Lillehei,
and frustrated over being bound to a wall socket, he asked a local
electrical engineer and electronics consultant to investigate the possibility
of miniaturizing the stimulator and creating a battery-powered unit.
Recognizing that most complete heart block patients returned to their own
sinus rhythm within a couple weeks, Lillehei hoped that some type of
innovation might untether patients from a wall socket and serve as a
marcin
(Marcin)
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