Biomedical Engineering Reference
In-Depth Information
1
History and Development of Pacing
The development of pacing technology has always been
closely related to discoveries in the field of electricity and,
later, electronic components and materials. The first written
records of attempts to pace cardiac nerves or muscles in ani-
mals using electric current date back to the end of the eigh-
teenth century [1]. In the nineteenth century, successful
resuscitations of patients in cardiac arrest using electric cur-
rent were documented [2]. In addition, the interest in acu-
puncture increased; in 1825 electric current was applied for
the first time through thin-needle electrodes, derived from
acupuncture needles. Thus, electroacupuncture was devel-
oped with the purpose of applying electric current to pace
muscles, nerves, and organs.
The first attempt to pace the heart using electric impulses
was recorded in 1828. Later, experiments on animals were
conducted, where cardiac arrest was induced by a chloro-
form overdose, and the contractions of the heart muscle were
restored by means of an electric current. It emerged that the
rate of pacing must exceed the intrinsic heart rate to induce
the pacing effect. The possibility of inducing ventricular
fibrillation using electric current and repetitive cardiover-
sions by strong current pulses was tested [ 3, 4 ] . The fi rst por-
table ambulatory resuscitation apparatus was designed. At
the turn of the nineteenth century, discoveries were made in
the field of cardiac physiology and in the cardiac conduction
system [ 5 ] . The cardiac automaticity gradient was discov-
ered, and scientific articles dealing with pathophysiology of
tachycardia and bradycardia were published.
It is interesting that the experimental and clinical findings
did not result in systematic clinical research in pacing and
defibrillation. Research on animals started in Europe only in
the 1920s. Since the 1930s, a great number of crucial scientific
studies in the field of cardiac electrophysiology was pub-
lished - in particular in the USA - and today the studies may
be retrieved from digitized scienti fi c databases [ 6, 7 ] .
1.1
The Beginnings of Pacing Technology
The first external pacemakers were produced in the USA in
the early 1930s. These devices were operated by a hand crank
with a spring motor, which turned a magnet to induce an
electric current. The motor was capable of pacing for 6 min.
The pulses were supposed to be applied through a transtho-
racic needle. These pacemakers were named
Hyman I
and
II
after their designer. The devices were too bulky and weighed
more than 7 kg. However, type II could be carried in a case
with a handle. Later analyses showed that these devices
would probably not have been capable of providing effective
pacing pulses in real situations, yet they were the oldest
known devices designed specifically for the purpose of
resuscitation from cardiac arrest. In the 1940s, the first work-
ing devices for external defibrillation were described. They
made use of alternating current, and their application was
successful only in connection with administration of drugs
and heart massage [ 3, 8 ] .
The first implantable pacemaker was implanted in a man
in 1958 in Sweden. The pacemaker worked for several hours.
The system comprised a steel lead, which was implanted
epimyocardially. The pacemaker proper was equipped with a
nickel-cadmium battery and sealed in epoxy resin [9, 10].
Because of the insufficient reliability of implantable pace-
makers, external pacemakers with a connection to a tempo-
rary transvenous lead in the cephalic vein were used for
pacing in the late 1950s. In 1959, for instance, a pacemaker
intended for a long-term application was used in a 67-year-
old patient with second- and third-degree atrioventricular
(AV) block. After the implantation of a transvenous lead and
subsequent hospitalization, the patient was discharged to
home care until November 1962. He was paced by means of
a battery-powered device that could also sense the intrinsic
