IEEE Spectrum November, 2008 - 31

first dedicated research into the mechanisms of electric shock, tive pulse-to deliver the shock. That insight proved to be one
however, emerged from quite the opposite effect-electricity's of the most critical technical advances in the development of
ability to kill. When General Electric, the company cofounded defibrillators. He published a short article on his use of biphaby Thomas Edison, switched from direct-current to alternating- sic shocks to resuscitate animals, but the idea didn't really take
current transmission in the early 1900s, linemen began to die hold until a Lithuanian-born American cardiologist, Bernard
from accidental electrocution. In response, GE funded research Lown, built a dc defibrillator. Lown used his defibrillator to
at several universities to study what made electric current lethal. treat patients suffering from ventricular tachycardia, a less
Two electrical engineering professors, William Kouwenhoven ominous arrhythmia that also responds to shocks. He later
and Guy Knickerbocker, at Johns Hopkins University, in had defibrillators built using Gurvitch's schematics, but most
Baltimore, tested the phenomenon by shocking stray dogs to U.S. researchers still refer to Gurvitch's breakthrough discovdeath. Serendipitously, they noticed that a second ac shock ery as the Lown waveform.
could sometimes bring an electrocuted dog back to life.
Kouwenhoven and Knickerbocker's observation was
he core component of a defibrillator has always been
picked up by a pioneering cardiac surgeon, Claude Beck, at
the capacitor, which stores the energy needed for the
the University Hospitals of Cleveland. He began delivering ac
shock. The first "portable" defibrillator, built in 1965,
directly to the exposed hearts of animals he had put into ven- weighed 70 kilograms without batteries and was designed to
tricular fibrillation. Beck might have continued methodically be plugged into an ambulance's starter battery. The device conwith his animal experiments, except that in 1947 a 14-year-old sisted of a large Mylar-film capacitor capable of storing a 4000-V,
patient's heart stopped during surgery. Out of desperation, Beck 400-joule charge, a charging circuit (to convert the 12 V from the
ordered that his research unit be brought up from the hospital's car battery to 4000 V), a gas discharge relay, and a large inductor.
basement. This simple defiWhen the capacitor discharged,
brillator consisted of a transthe current passed through the
former to isolate the patient
inductor to reduce its peak curPrévost & Batelli
from the 110-volt ac wall suprent, which, at up to 80 amperes,
ply, a variable resistor to limit
might damage the heart instead
the current to a heart-safe
of defibrillating it.
Kouwenhoven
value, and two metal tableThis early device had a
spoons with wooden hanbutton that controlled the
Gurvitch
dles to deliver the jolt to the
gas discharge relay; when
exposed heart [see "Saved by
pressed, it completed a cira Spoon"].
cuit and delivered a strong
Modern biphasic
The first shock failed, so
single pulse from the capacBeck administered a second.
itor through the inductor
That brought the patient back
to the patient. The current
0
5
10
15
20
25
to life, and the event made
was transmitted through
national news. But because
paddles the size of clothing
so little was known about
irons placed on the chest so
Time (milliseconds)
why the technique worked
that the administrator could
wave sculptiNg: from the 1890s, experimenters defibrillated
or how to improve it, these
get a good grip. Because dry
with some success. naum gurvitch's waveform, however,
crude ac systems persisted
skin is an insulator, a rescuer
became the bridge to the modern aeD. soURCe: MaRK W. KRoll
for several years. Recipients
had to apply sufficient presof closed-chest ac defibrillasure to overcome its impedtion tended to suffer unpleasance. (The Johns Hopkins
ant side effects from the large steady currents, including broken engineers Kouwenhoven and Knickerbocker noticed that this
ribs and damage to the heart muscle-if they were saved at all. heavy pressure also caused a patient's blood pressure to spike.
Unknown to Beck and his colleagues in America, investi- That's how the chest-compression technique now used in cargators in Europe and Russia were far ahead of them in animal diopulmonary resuscitation, or CPR, was invented. [See the
research and were beginning to use a single pulse, or dc, defi- online sidebar, "Rethinking CPR," at http://www.spectrum.
brillation. In the 1890s, Jean-Louis Prévost and Frederic Batelli, ieee.org/nov08/cprsb.])
two physiologists at the University of Geneva, revived animals
These defibrillators required two trained operators: somewith a capacitor discharge delivered directly to the heart.
one to press the paddles against the chest and someone else to
Decades later, one of their graduate students, Lina Schtern, push the button. One of the operators had to first acquire and
moved to the Soviet Union and continued to refine the interpret the electrocardiogram, or EKG. Then someone had to
technique-that is, until she received a death sentence during remove the leads from the EKG because the shock would othera crackdown on intellectuals under Joseph Stalin. She was wise destroy its electronics.
eventually pardoned by the dictator himself, who (according
The device wasn't truly portable-even after some design
to accepted rumor) believed that she could bring people back modifications, the cumbersome units weighed between 20 and
from the dead.
40 kg. There was also no safeguard to keep the device from
In Moscow, at the peak of World War II, a young student being used in the wrong situation-say, erroneously shocking
of Schtern's named Naum Gurvitch made rapid advances in an unresponsive individual who might actually be experiencdefibrillation. Gurvitch was the first to suggest using a bipha- ing a seizure or a fainting spell.
sic waveform-a sizable positive jolt followed by a small negaTwo major advances cut the energy requirement for defiShock voltage (no units)

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NovEmbEr 2008 * iEEE SpEctrum * NA

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2008