1. Pacing the Heart: Growth and Redefinition of a Medical Technology, 1952-1975
Author(s): Kirk Jeffrey
Source: Technology and Culture, Vol. 36, No. 3 (Jul., 1995), pp. 583-624
Published by: The Johns Hopkins University Press on behalf of the Society for the History of Technology
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2. Pacing the Heart: Growthand
Redefinition a MedicalTechnology,
of
1952-1975
KIRK JEFFREY
A cardiac pacemaker delivers electrical impulses to the heart so as
to coordinate the pumping action of the upper and lower chambers
(atria and ventricles) and speed the heart up from standstill or an
unduly slow rate.' Between 1952 and the mid-1970s, the practice of
cardiac pacing grew from "promising report" to "standard proce-
dure" and then kept on growing.2 The earliest devices stimulated the
heart from outside the patient's body, but implanted pacemakers
made their appearance at the end of the 1950s. The number of pa-
tients relying on pacemakers in the United States expanded to more
than 150,000 by 1975.3 In the 1990s, estimating conservatively,
500,000-600,000 Americans carry pacemakers; more than 110,000
pacemakers are implanted annually in the United States by about
DR. JEFFREY is professor of history at Carleton College. He thanks Carleton College
for research support through the Faculty Development Endowment. Professor Clifford
E. Clark, Jr., and the Technologyand Culture referees offered helpful criticism.
1Its focus on slow heart rates
(bradycardia, rates below sixty beats per minute) distin-
guishes the pacemaker from devices that use electrical shocks to halt unduly rapid
heart rates (tachycardia) and random electrical behavior with consequent loss of orga-
nized beats (fibrillation). My definition of the pacemaker is time bound: as Victor
Parsonnet and Alan D. Bernstein have observed, "The definition of a pacemaker is
imprecise, because now that word is applied to electrical stimulators that treat either
slow or fast rhythms. In this computer age, a 'pacemaker' is essentially an implanted
microcomputer that can be adapted noninvasively to any type of stimulation or sensing
that is required." See Victor Parsonnet and Alan D. Bernstein, "Cardiac Pacing after
25 Years: A Practical Approach to Growing Complexity," in Modern Cardiac Pacing,
ed. S. Serge Barold (Mount Kisco, N.Y., 1985), pp. 959-72, at 959. Cardiac electrostim-
ulation is employed diagnostically (e.g., in an electrophysiology workup) as well as
therapeutically, but this article limits its scope to therapeutic uses of pacing.
2John B. McKinlay, "From 'Promising Report' to 'Standard Procedure': Seven Stages
in the Career of a Medical Innovation," Milbank Quarterly59 (1981): 374-411.
3Victor Parsonnet and Marjorie Manhardt, "Permanent Pacing of the Heart: 1952
to 1976," AmericanJournal of Cardiology39 (1977): 250-56.
? 1995 by the Society for the History of Technology. All rights reserved.
0040-165X/95/3603-0004$0 1.00
583

3. 584 KirkJeffrey
8,000 physicians.4Pacing-related hardware, facilities, and services
have cost Medicarewell over $1 billion annually in recent years.5
A symbol in its early years of the fabulous promise of medical
technology, pacing in the early 1980s became a lightning rod for
doubts and concerns about the American system of health care. To-
day, in a time of national debate about the cost and distribution of
health care, a review of a success story involving high-tech medicine
may help us understand one important underlying dynamic in the
health-care system: the reciprocal and interactive process by which
technological change and new concepts of disease stimulate each
other, thereby creating a powerful momentum for growth.
A technologicaldevice drawsus towardthe outlook and aspirations
of its sponsors, the groups that introduced it and shape its ongoing
development and social meaning.6Hence, this articlespeaks of pacing
4Becauseno national pacemakerregistryexisted during the period covered by this
article, these and other figures must be taken as approximations.Here I follow the
estimates of Parsonnet and his associates,who have conducted national surveys of
pacing practicesevery few years since 1971: Alan D. Bernstein and Victor Parsonnet,
"Surveyof CardiacPacingin the United Statesin 1989,"American Journalof Cardiology
69 (1992): 331-38. Their figure of 110,500 pacemakersimplantedin 1989 (apparently
misprintedas 117,000) included 89,445 primary(first-time)implantationsand 21,055
replacements.But another set of observerssuggests a figure of 250,000 implantations
per year: NicholasJ. Stamatoet al., "PermanentPacemakerImplantationin the Car-
diac Catheterization Laboratory versus the OperatingRoom,"PACE(Pacingand Clini-
cal Electrophysiology) (1992): 2236-39.
15
5The Health Care Financing Administrationreported 59,588 hospital discharges
following the implantationof pacemakersin 1986-a suspiciouslylow number. Even
so, considering that the likely cost of pacing over the remaining life of an elderly
person ran to at least $30,000 in the late 1980s, then an annual cohort of 60,000
Medicarepacemakercandidateswould represent future direct pacing-relatedcosts of
some $1.8 billion (U.S. Health Care FinancingAdministration, Office of Researchand
Demonstrations, Health Care Financing: Special Report: Hospital Data by GeographicArea
for Aged Medicare Beneficiaries:SelectedProcedures, 1986 [Baltimore, June 1990], 2:77).
Indirect costs to the health-caresystem are much more difficult to estimate. On the
one hand, because they live longer, people carryingpacemakersincur other medical
costs that they would not have incurredbefore the era of pacing. On the other hand,
they are better able to care for themselves,less likely to require long-term care, and
at a greatly reduced risk of cardiac arrest with its attendant emergency procedures
(cardiopulmonary resuscitation,ambulance,intensivecare) or of majorfracturesfrom
falls. For a general discussionof the cost-effectivenessof cardiacpacing, see Richard
Sutton and Ivan Bourgeois, Foundations of Cardiac Pacing, Part I (Mount Kisco, N.Y.,
1991), pp. 303-13.
6CompareSusan E. Bell's remarkthat a technology is "the product or embodiment
of human activity":SusanE. Bell, "ANew Modelof MedicalTechnologyDevelopment:
A Case Study of DES," Researchin the Sociologyof Health Care 4 (1986): 1-32, at 2. On
the concept of sponsorship,see Ron Westrum,Technologies Society
and (Belmont,Calif.,
1991), pp. 171-93.

4. Pacing the Heart 585
more often than the pacemaker.Pacing is an emerging medical sub-
specialty with its own textbooks, professional organizations, journals,
conventions, and competency examination.7 More broadly still, pac-
ing has grown into a subculture complete with creation myths;
revered elders; complex networks of friendship and rivalry encom-
passing physicians, business executives, and engineers; and a distinc-
tive language bewildering to the outsider.
To understand fully cardiac pacing, one should follow develop-
ments in pacemaker hardware, techniques of implantation, medical
understanding of heart arrhythmias, the rise of the medical-device
manufacturing industry, and the policies of governments toward the
consumption of pacing devices and services. It is not an exclusively
American story: research and inventive activity in western Europe,
Canada, and Japan have contributed in important ways to the growth
and redefinition of cardiac pacing. This article has more modest aims:
it limits its scope to the shifting roles of heart surgeons and cardiolo-
gists in the United States during the first quarter century of cardiac
pacing, an era of explosive growth and repeated technological re-
definition.8 Doctors played several parts, acting sometimes as technol-
ogists who invented and advocated new pacing hardware and tech-
niques, sometimes as practitioners who applied the technology of
pacing to real patients. Some doctors also served as advance scouts
7Seymour Furman et al., A Practiceof Cardiac Pacing, 3d ed. (Mount Kisco, N.Y.,
1993), is one of several current texts; J. Warren Harthorne et al., "North American
Society of Pacing and Electrophysiology(NASPE),"PACE 2 (1979): 521-22; Pace-
maker Study Group, "OptimalResourcesfor ImplantableCardiacPacemakers," Circu-
lation68 (1983): 227A-244A; J. WarrenHarthorne and Victor Parsonnet,"Training
in Cardiac Pacing," Journal of the American College of Cardiology 7 (1986): 1213-14;
Seymour Furman, Editorial:"Certificate Special Competence in Cardiac Pacing,"
of
PACE 9 (1986): 1; Victor Parsonnet, "CardiacPacing as a Subspecialty," American
Journalof Cardiology (1987): 989-91. The leadingjournal in the field, PACE,was
59
founded in 1978.
8An arrhythmiais a deviation from normal heart rhythm. I use the terms doctor
and physicianas synonymsreferring to persons holding the M.D. degree and licensed
to practicemedicine.Thoracic(chest)surgeryemerged as an informalsurgicalsubspe-
cialtyin the 1930s, with board certificationdating from 1950. The term cardiothoracic
(heart and chest) surgery came into use during the 1950s. Cardiologywas formally
created as a subspecialtyof internal medicine in 1940. Cardiologistsattend to diseases
of the heart and vascularsystem;they employ invasiveproceduressuch as catheteriza-
tion but are not certified to perform heart surgery. RosemaryStevens,American Medi-
cine and thePublicInterest (New Haven, Conn., 1971), is the classic study of medical
specializationin the United States; see also Joel D. Howell, "The Changing Face of
Twentieth-Century American Cardiology,"Annals of InternalMedicine105 (1986):
772-82.

5. 586 KirkJeffrey
who identified new heart arrhythmiasthat might be suitablefor treat-
ment through pacing.9
Cardiac pacing proved itself an extraordinarily flexible technol-
ogy-it successfullymanaged chronic diseases not even defined when
Paul M. Zoll announced his external pacemaker in 1952.10 Doctors'
understanding of "cardiac pacing" repeatedly changed as medical
researchersrepeatedly framed new heart arrhythmiasfor which pac-
ing has seemed the appropriate therapy. Knowledge gained in the
laboratorywas passed to clinicianswho, in turn, informed biomedical
engineers of new needs and opportunities for pacing that required
new pacing hardware.1lThe very success of clinical cardiac pacing
stimulated further basic research into conduction disorders of the
heart, bringing the process of transmissionof knowledge full circle.
This account of the invention of effective heart pacemakers and
the development of pacing as a practicaltherapy thus asks what car-
diac pacing has meant, principallyto the surgeons and cardiologists
who examined patients and implanted pacemakers,at different mo-
ments in the early history of the field. It highlights several episodes
of substantialredefinition in which significant expansions of the list
of medical indications for pacing occurred. It describes the field of
cardiac pacing at the end of the 1950s and 1960s and notes the orga-
nizationalforces shaping the field in each decade, for physicianswho
specialized in pacing never made choices in a vacuum. The early
expansions of the meaning of cardiac pacing prepared the field for
rapid growth once Medicarewas in place. One might expect that the
centrality of an artifact, the pacemaker,would endow pacing with a
less evanescent character.Not so: the meaning of terms like "pacing"
and "pacemaker" been so thoroughly transformedthat what they
had
9Federal regulation can be dated from passage of the Medical Device Amendments
of 1976 (amendments, i.e., to the Food, Drug, and Cosmetic Act of 1938, which had
created the Food and Drug Administration). My attention to "streams of activity"
shaping the technology of pacing owes much to Bell, "A New Model" (n. 6 above),
and to Joel D. Howell, "Early Perceptions of the Electrocardiogram: From Arrhythmia
to Infarction," Bulletin of the History of Medicine 58 (1984): 83-98, and "Diagnostic
Technologies: X-Rays, Electrocardiograms, and CAT Scans," Southern California Law
Review 65 (1991): 529-64.
0lOn artifactual flexibility, see Wiebe E. Bijker, "The Social Construction of Bakelite:
Toward a Theory of Invention," in The Social Constructionof TechnologicalSystems,ed.
Wiebe E. Bijker, Thomas P. Hughes, and Trevor Pinch (Cambridge, Mass., 1987), pp.
159-87; and Howell, "Diagnostic Technologies."
"A clinician is any doctor who engages in the practical work of observing and
treating patients (clinical practice), as distinguished from laboratory research or theo-
retical study.

6. Pacing the Heart 587
signified by the mid-1970s bore little resemblance to the definitions
and assumptions of twenty years earlier.
Pacing for EmergencyResuscitation, 1952
Although there had been some earlier experiments with pulsed
electrostimulationto resuscitatehuman beings from standstill of the
heart, cardiac pacing as a set of systematicmedical procedures origi-
nated in the 1950s.12Zoll, a cardiologist at Beth Israel Hospital in
Boston, invented an external pacemaker and reported having used
it to revive a patient in 1952. Zoll'sapproach to pacing the heart was
impressive for its simplicityand directness: the pacemakerconsisted
of off-the-shelf components including a plug-in electrical stimulator
familiar to most doctors from their student days and simple needle
electrodes inserted beneath the skin of the patient's chest on either
side of the heart. (Zoll later substituted standard electrocardiograph
electrodes that were strapped to the chest.) Electricalimpulses of two
milliseconds' duration, fired through the chest with an amplitude
of 50-150 volts, would stimulate the ventricles to contract, thereby
restoring a circulationof blood to the brain and the body. Zoll'sfirst
publication announced that this pacemaker had managed the heart-
beat in an elderly patient for fifty-twoconsecutive hours.13
External pacing came into widespread use in American hospitals
12Kirk
Jeffrey, "The Invention and Reinvention of Cardiac Pacing," CardiologyClinics
10 (1992): 561-71, argues that the basic scientific and technical knowledge required
for building simple pacemakers and pacing the heart for brief periods of time existed
by the 1920s. However, chronic arrhythmias and "sudden cardiac death" (death within
24 hours from a heart attack or cardiac arrest) had not yet been defined as critical and
solvable problems by physicians specializing in diseases of the heart. Working sepa-
rately, physician-inventors in Australia and New York had actually invented pacing
devices in the mid-1920s and early 1930s, but their work received little attention and
no support from the medical community. The situation had changed considerably by
the late 1940s as a result of many factors: improved understanding of arrhythmias,
experience with open-chest defibrillation, rising physician confidence about working
around and even within the exposed human heart, and the postwar redefinition of
the hospital as a technological center for the delivery of acute-care medicine.
13Paul M. Zoll, "Resuscitation of the Heart in Ventricular Standstill by External
Electric Stimulation," New EnglandJournal of Medicine 247 (1952): 768-71. An electrical
impulse delivered to a single point in the myocardium (the muscular tissue of the
heart) will be propagated from cell to cell. This depolarization results in mechanical
contraction of the heart muscle. The energy required to instigate this process is quite
small, on the order of 10-50 microjoules, if delivered directly to the excitable tissue.
Zoll's external pacing system required a high voltage because of the impedance associ-
ated with the patient's skin and subcutaneous tissues, the surface area of the electrodes,
the short pulse duration, and other factors. In modified form, short-term external
pacing remains a widely used hospital technology.

7. 588 KirkJeffrey
during the 1950s.14 But this was not pacing as the public knows it
today: Zoll's invention carried with it a set of assumptions and prac-
tices quite different from those now associated with implanted cardiac
pacemakers. This first version of pacing meant emergencyresuscitation
in the hospital from ventricular standstill. A pulse generator the size
of a breadbox that plugged into the alternating current (AC) electrical
system implied a bedridden patient. The high voltage required to
capture the heartbeat implied very short bouts of pacing-from min-
utes to hours-and patients who were unconscious or sedated. Zoll's
famous patient R. A. had been able to eat, sleep, and carry on conver-
sation during treatment with the pacemaker, but this was uncommon;
the artificial pulses caused painful muscle contractions in the upper
chest that most patients found difficult to tolerate.'5
Zoll invented his pacemaker to address an uncommon occurrence
known as a Stokes-Adams attack, a potentially lethal complication of
complete heart block. In heart block, the heart's natural electrical
signal that triggers atrial and then ventricular contraction starts out
in normal fashion from the sinus node, its source high in the right
atrium; when the impulse reaches the floor of the right atrium, con-
duction cells within the heart muscle fail to propagate it on to the
ventricles, the major pumping chambers of the heart. One of several
secondary "pacemakers" below the site of the block may then stimu-
late the ventricles to contract; but these backup pacemakers fire more
slowly than the normal one, and because of the block the atrial and
ventricular contractions no longer occur in a coordinated man-
ner.16 (See fig. 1.)
14
The device was put into commercial production by Electrodyne, a small electronics
firm outside Boston. Morris J. Nicholson et al., "A Cardiac Monitor-Pacemaker: Use
during and after Anesthesia," Anesthesiaand Analgesia 38 (1959): 335-47, gives a con-
temporary description. For a full discussion of the technical issues, see Pierre J. Birkui
et al., eds., Noninvasive TranscutaneousCardiacPacing (Mount Kisco, N.Y., 1992).
External pacemakers introduced in the 1980s have greatly reduced this problem:
Jerry C. Luck and Michael L. Martel, "Clinical Applications of External Pacing: A
Renaissance," PACE 14 (1991): 1299-1316.
16Heart block is also known as atrioventricular or AV block.
Cardiologists then and
now distinguish three stages in the development of the condition. In first-degree block,
signals reach the ventricles after a delay; in second-degree block, some signals reach
the ventricles while others do not. The text describes third-degree or complete block.
See Johan Landegren and Gunnar Biorck, "The Clinical Assessment and Treatment
of Complete Heart Block and Adams-Stokes Attacks," Medicine 42 (1963): 171-96. For
a historical treatment of medical understanding of heart block, see David C. Schechter
et al., "History of Sphygmology and of Heart Block," Diseases of the Chest 55, suppl. 1
(June 1969): 535-79. Physiologists believed that most cases were a result of coronary
artery disease; heart block was also known to be an occasional sequel to heart attack:
C. K. Friedberg et al., "Nonsurgical Acquired Heart Block," Annals of the New York

8. Pacing the Heart 589
The person with heart block may not be able to tolerate physical
activity and may show symptoms of congestive heart failure. Sooner
or later, the person may also begin to experience brief episodes of
dizziness or unconsciousness from inadequate cerebral circulation.
Eventuallythe circulationof blood may cease as the ventricles go into
fibrillation(uncoordinated quivering) or come to a standstill.Loss of
consciousness resulting from heart block was called a Stokes-Adams
attack,and mean life expectancyfrom the first such attackwas known
to be a matter of months because sooner or later an episode would
Promptlyapplied, the Zoll pace-
last long enough to kill the patient.17
maker maintained a circulationthrough the few minutes of a Stokes-
Adams attack that took the form of ventricular standstill.'8Pacing
thus began as an emergency procedure; it resembled the use of in-
hospital defibrillationtoday. But at first Zoll did not conceive of pac-
ing as a possible way to manage the underlying degenerative disease,
complete heart block.
Pacing for PostsurgicalHeart Block, 1958
The earliest transformation of pacing came quickly: in the mid-
1950s a new group of users, the first open-heart surgeons, decided
that cardiacpacing might solve a hitherto unknown complicationthey
were encountering. In adapting Zoll's original idea to their needs,
the surgeons invented a second variety of short-term pacing.
The early open-heart operationswere often performed on children
born with congenital defects and known as "blue babies." By early
1957, C. Walton Lillehei'ssurgical group at the Universityof Minne-
sota had carried out 305 open-heart operations but had discovered
that approximately one child out of ten developed complete heart
block as a consequence of the surgery. The surgeons concluded that
Academyof Sciences 111 (1964): 835-47. The intense research on conduction diseases
that got under way with the invention of cardiac pacing also demonstrated that with
age, the specialized conduction fibers could gradually degenerate and lose the capacity
to repolarize: Michael Davies and Alan Harris, "Pathological Basis of Primary Heart
Block," British Heart Journal 31 (1969): 219-26.
17 MArten Rosenqvist and Rolf Nordlander, "Survival in Patients with Permanent
Pacemakers," CardiologyClinics 10 (1992): 691-703.
18Zoll held that the great majority of Stokes-Adams attacks took the form of stand-
still, but this was a contested point. Ventricles in fibrillation would have to be brought
to standstill by means of a strong shock before effective pacing could begin; by itself,
a pacemaker would be ineffective in such a case. Since the 1950s the term Stokes-
Adams disease has fallen into disuse. For an authoritative latter-day discussion I have
relied on Douglas P. Zipes, "Specific Arrhythmias: Diagnosis and Treatment," in Heart
Disease, ed. Eugene Braunwald, 4th ed. (Philadelphia, 1992), pp. 667-725, esp. pp.
710-15.

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FIG. 1.-Electrocardiogram of complete heart block showing complete dissociation of atrial ac
plexes). Elapsed time from one heavy vertical line to the next is 0.2 second. The P-P intervals ind
minute, while the intervals between QRS complexes indicate a ventricular rate of 35 beats per min
of
Mastering Dysrhythmias: Problem-SolvingGuide [Philadelphia, 1988], p. 238; reprinted courtesy
A

10. Pacing the Heart 591
they were occasionally disrupting the heart's conduction pathways
while repairing defects in the ventricular septum, the partition be-
tween the right and left ventricles. The complication almost always
killed the patient.'9
Short-termpacing seemed an obvious way to manage this problem;
but with postsurgical heart block it would be necessary to pace a
child's heart steadilyfor days or weeks to give the specializedconduc-
tion cells of the heart time to heal. The Zoll pacemakerseemed more
appropriatefor brief and occasionalbouts of pacing. Certainly,young
children could not tolerate the high pacing voltages without sedation.
The group at Minnesotatherefore began to sew a stainlesssteel wire,
coated with Teflon except at its tip, into the wall of the ventricle (the
myocardium)during open-heart surgery. They would bring the wire
out through the surgical wound, bury a second wire under the pa-
tient's skin as an indifferent electrode, and connect both to a Zoll
pulse generator.20Days later, the surgeon could pull gently on the
wire and dislodge it from the myocardium. By the fall of 1957, Lil-
lehei was following this procedure whenever a patient showed signs
of block during an open-heart operation.21
Since the myocardial pacing wire could capture control of the
heartbeat at a voltage level at least one order of magnitude lower
than external pacing,22 patient could remain painlesslydependent
the
on it for days or weeks. But the pulse generator was still a large device
19Leonard G. Wilson, Medical Revolution in Minnesota: A History of the University of
Minnesota Medical School (St. Paul, Minn., 1989), pp. 516-19; Dwight C. McGoon et
al., "Surgically Induced Heart Block," Annals of the New YorkAcademyof Sciences 111
(1964): 830-34; interview with C. Walton Lillehei, St. Paul, Minnesota, July 25, 1990.
Blue babies were so called because inadequate oxygenation of the blood imparted a
bluish cast to their skin.
20All pacemakers consist of three elements: a pulse generator, electrodes (electrical
conductors through which a current enters or leaves a medium such as heart tissue),
and a lead (one or more insulated wires connecting the pulse generator to the elec-
trode). In the pacemaker invented at the University of Minnesota, the tip of the myo-
cardial wire was the electrode; the wire itself, the lead. This article, like all writings on
cardiac pacing, speaks of "the atrium" and "the ventricle" as if a human being had
only one of each. In fact it is necessary to deliver a pacing impulse only to the chambers
on one side of the heart since the cells of the myocardium will propagate it to the
other.
21William L. Weirich et al., "The Treatment of Complete Heart Block by the Com-
bined Use of a Myocardial Electrode and an Artificial Pacemaker," Surgical Forum 8
(1958): 360-63; C. Walton Lillehei et al., "Direct Wire Electrical Stimulation for Acute
Postsurgical and Postinfarction Complete Heart Block," Annals of the New YorkAcademy
of Sciences 111 (1964): 938-49; Wilson, pp. 516-19; Lillehei interview.
22Lillehei's surgical team reported capture at output voltages in the range of 1.5-4.5
volts: Weirich et al., p. 362.

11. 592 KirkJeffrey
FIG. 2.-C. Walton Lillehei with a young patient, Saturday Evening Post, March 4,
1961, p. 13. The boy is wearingan externalpulse generator,the Medtronic5800. The
two output terminalsprotrude from the top of the device. One of the knobs on the
front controls electricaloutput, the other the pacing rate. For a full description, see
C. WaltonLilleheiet al., "Transistor Pacemaker Treatmentof CompleteAtrioven-
for
tricular Dissociation," Journal of the AmericanMedical Association 172 (1960): 2006-10.
(Photo courtesyof Medtronic,Inc.)
plugged into the AC electrical system. The surgeons at Minnesota
wished to get their child-patients out of bed and moving around;
they worried that an electrical malfunction could send a patient into
ventricular fibrillation (VF), a lethal arrhythmia. Lillehei therefore
asked an engineer who repaired electronic equipment at the medical
school, Earl Bakken, if he could make a small battery-powered pulse
generator. Delivered early in 1958, Bakken's new device was powered
by flashlight batteries and employed newly available components
called transistors. Small enough to hold in the hand, it could be car-
ried in a pouch or holster worn at the belt or around the neck (fig.
2). The small firm that Bakken and his brother-in-law had founded,
Medtronic, Inc., soon began to produce the units in response to re-
quests from surgeons around the United States. This early experience
in pacing prepared the firm to grow along with the growth of cardiac

12. Pacing the Heart 593
pacing. Medtronic soon became the world's largest manufacturer of
pacemakers, a position it still holds today.23
Pacing in the 1950s: Treatment Acute Illness
for
Lillehei's myocardial approach to the heart emerged as an offshoot
of the revolution in heart surgery, but it still bore a strong resem-
blance to Zoll's original version of pacing. In both external and myo-
cardial pacing, the patient was assumed to be gravely ill, confined to
the hospital, and pacemaker-dependent. Both systems ministered to
acute crises, whether Stokes-Adams attacks or postsurgical heart
block. In both, the pacemaker was defined as a piece of hospital
equipment; its transformation into a more or less permanent addition
to the patient's own body was still a few years away.24
It might be asked why physicians chose cardiac electrostimulation
to drive the heart rather than some entirely different technology-
perhaps the administration of stimulating drugs such as atropine or
isoproterenol. Researchers had experimented since the 1920s with
drugs that stimulated the heart; while these were often effective for
brief intervals in particular patients, it proved extremely difficult to
administer an appropriate amount of a drug at a steady rate, hour
after hour and day after day. More broadly, by the postwar years
doctors had grown accustomed to thinking of the heart as an electro-
mechanical system, a "pump" activated by electrical impulses that
the specialist could comprehend by analysis of the electrocardiogram
(ECG).25 Investigators of the 1950s such as Zoll and Lillehei knew of
the new technique of open-chest defibrillation, a form of electrostim-
ulation that bore an obvious resemblance to pacing and had resusci-
tated human beings from VF beginning in 1947. Then too, by good
fortune complete heart block happened to be the perfect "electrical
failure" to take up: it could be managed effectively in many cases by
means of a device that was straightforward in concept. The pioneers
in cardiac pacing were able to gain hands-on experience while using
23For a definition of fibrillation, see n. 1 above. See also C. Walton Lillehei et al.,
"Transistor Pacemaker for Treatment of Complete Atrioventricular Dissociation,"
Journal of the American Medical Association 172 (1960): 2006-10; Wilson, pp. 519-21;
and Lillehei interview. Steven M. Spencer, "Making a Heartbeat Behave," Saturday
Evening Post, March 4, 1961, pp. 13 ff., gives an interesting popular account of pace-
maker development that includes interviews with several of the early patients.
24Jeffrey, "Invention and Reinvention" (n. 12 above).
25Christopher Lawrence, "Moderns and Ancients: The 'New Cardiology' in Britain,
1880-1930," Medical History, suppl. 5 (1985): 1-33; Howell, "Early Perceptions of the
Electrocardiogram (n. 9 above); Lynn Payer, Medicine and Culture (New York, 1988),
pp. 74-75, 79-85.

13. 594 KirkJeffrey
relatively simple devices that did not require sensing as well as pacing
functions or produce complex electrocardiograms. While attempts
to control heart block with drugs ran into repeated problems, the
pacemakers of the late 1950s and early 1960s could quickly boast a
number of remarkable success stories. And doctors are much influ-
enced by case histories.26
Physician-inventors and the electronic engineers who advised and
worked with them were clearly the dominant influences on the na-
scent field of pacing, its "sponsors." By necessity, pacing at first re-
mained largely confined to major hospitals; but it began to spread in
the late 1950s and early 1960s as part of a package that included
thoracic surgery and acute cardiac care.27 With its operating rooms,
catheterization labs, and skilled nursing care, and with procedures
such as electrocardiography, AC defibrillation, and cardiac catheter-
ization, the large hospital had already emerged by the mid-1950s as
the appropriate locus for the practice of acute-care medicine relating
to the heart. Pacing was not only nurtured in the hospital, but it
promised to reinforce the hospital's role in the acute care of heart
disease.28
These institutional and technological developments took place in a
cultural climate that encouraged an activist, experimental approach
in cardiology and heart surgery. Cheered by the dramatic achieve-
ments of military medicine during World War II, the American pub-
26On pharmacologic control of cardiac arrhythmias, see Paul B. Beeson, "Changes
in Medical Therapy during the Past Half Century," Medicine 59 (1980): 79-99. Lil-
lehei's group at Minnesota tried to manage seven cases of postsurgical heart block
with epinephrine, aphedrine, atropine, and sodium lactate in 1954-55; they had no
survivors. They then switched to isoproterenol (Isuprel) in 1955-57; out of nineteen
cases, they had nine successes, five that remained in complete block, and five deaths.
Results like this drove doctors very quickly to electrostimulation. See Lillehei et al.,
"Direct Wire Electrical Stimulation" (n. 21 above). Defibrillation terminates the random
electrical activity of a fibrillating heart by means of a strong electrical shock. At first,
doctors applied paddle electrodes directly to the exposed heart: Claude S. Beck et al.,
"Ventricular Fibrillation of Long Duration Abolished by Electric Shock," Journal of the
AmericanMedical Association 135 (1947): 985-86.
27Paul M. Zoll, "The Cardiac Monitoring System" (interview), Medical News 186
(1963): 34-36; Bernard Lown, "Intensive Heart Care," Scientific American 219 (July
1968): 19-27; Louise B. Russell, Technologyin Hospitals (Washington, D.C., 1979), pp.
41-70.
28Russell; Paul Starr, The Social Transformation AmericanMedicine (New York, 1982);
of
Joel D. Howell, "Machines and Medicine: Technology Transforms the American Hos-
pital," in The AmericanGeneralHospital: Communities and Social Contexts,ed. Diana Eliza-
beth Long and Janet Golden (Ithaca, N.Y., 1989), pp. 109-34; Rosemary Stevens, In
Sicknessand in Wealth:AmericanHospitals in the TwentiethCentury(New York, 1989), pp.
224-32; Jeffrey, "Invention and Reinvention" (n. 12 above).

14. Pacing the Heart 595
lic supported medical research and looked forward to rapid success
in the "war" against heart disease.29 David Sarnoff, chairman of the
board of the Radio Corporation of America and a noted technological
sage, probably captured the enthusiasm of many in picturing a future
time when "miniaturized electronic substitutes will be developed to
serve as long-term replacements for organs that have become defec-
tive through injury or age.... It is not too far-fetched to imagine a
man leading a normal life with one or more vital organs replaced by
the refined substitutes of the future."30
In spite of such optimism, we should not overstate the centrality
of cardiac pacing: to all but its sponsors, pacing at the end of the
1950s had the look of an intriguing but distinctly marginal new tech-
nology of medicine. Although postsurgical heart block had added
hundreds of new patients to the number who might be assisted by
pacing, the total population with Stokes-Adams disease or postsurgi-
cal block appeared small to most clinicians.31 The management of
electrical blockages in the heart might intrigue researchers, but com-
mercial prospects did not look particularly inviting. When representa-
tives from major manufacturing firms began to inquire about the
market for pacemakers in the late 1950s, pioneers in the field gave
them estimates on the order of five hundred units per year for the
United States. Such figures were probably based on the assumption
that a handful of external pulse generators, whether plug-in or
29U.S. Office of Scientific Research and Development, Committee on Medical Re-
search, Advances in Military Medicine (Boston, 1948); President's Commission on the
Health Needs of the Nation, Building America'sHealth (Washington, D.C., 1952); Starr,
pp. 335-51; Eugene Braunwald, "The Golden Age of Cardiology," in An Era in Cardio-
vascular Medicine, ed. Suzanne B. Knoebel and Simon Dack (New York, 1991), pp. 1-4.
30"Sarnoff Predicts 'Disease Machine,'" New YorkTimes (November 11, 1959), p. 28.
Sarnoff added, "One day artificial kidneys, lungs, and even hearts may be no more
remarkable than artificial teeth." Sarnoff had predicted in 1916 that the radio would
become a "household utility."
311 have found no direct discussions of the incidence of heart block or Stokes-Adams
disease from the period before 1960. Early investigators in cardiac pacing whom I
have interviewed all agree that estimates of the size of the prospective patient popula-
tion were minuscule and that clinicians saw very few cases in their careers because
complete heart block often terminated in death from cardiac arrest before a person
could see a physician. My impression is that the question of how many people had
heart block received little attention until after implantable pacemakers arrived on the
scene. Estimates then began to become both more precise and larger. See, e.g.,
Friedberg et al. (n. 16 above), p. 846. The most exhaustive study of the incidence of
heart block conducted during the period covered in this article is David B. Shaw and
Christopher A. Kekwick, "Potential Candidates for Pacemakers," British Heart Journal
40 (1978): 99-105. Shaw and Kekwick estimated the incidence of diagnosed cases of
heart block in their study area (Devon, England) at 97 per million population.

15. 596 KirkJeffrey
battery powered, could serve the needs of dozens or hundreds of
patients over a few years because the pacemakerwas a piece of hospi-
tal equipment, not (yet) a part of the patient'sown body. This misper-
ception ensured that larger companies would leave the market to
small specialty firms, such as Electrodyne and Medtronic, that had
already developed relationshipswith medical research teams.32
An ImplantablePacemaker ChronicHeart Block
for
In the late 1950s, a second and more thoroughgoing redefinition
of cardiac pacing got under way when a few physician-inventorsbe-
gan to think of pulsed electrostimulationas a way to solve the long-
term problem of chronic complete heart block by permanently sup-
planting the heart'sown failed conduction system.33 This meant that
the patient would receive electricalstimulationnot for a few days or
weeks but for months and years-ideally, for the rest of a lifetime.
Long-term pacing implied that the patient need not be confined to a
hospital bed but might become fully ambulatory,leave the hospital,
and lead the life of a semi-invalid.Rather than a brief and occasional
intervention, pacing would now become a permanent circumstance
in the life of each patient. Although no pioneers in pacing had yet
recognized it, long-term pacing also meant that the pacemakerwould
require some kind of routine follow-up managementthrough an out-
patient facility.
This revised version of cardiac pacing did not emerge naturally
and directly from existing practicesbut instead required that doctors
radicallyreorganize their thinking. Indeed, some physiciansinvolved
with pacing remained committed to the earlier concept of the pace-
maker as an emergency or short-terminstrument.34 Certainlythe new
version of cardiac pacing entailed radical changes in the design of
pacing technology and in the activities surrounding its use. As an
32Telephone interview with Sam E. Stephenson, Jr., August 30, 1991. According to
Bakken, the market-research firm Arthur D. Little estimated in 1960 that "the world-
wide, all-time market for pacemakers would be about ten thousand units": interview
with Earl E. Bakken, Fridley, Minnesota, May 23, 1990.
33This revised concept of pacing occurred to several research groups beginning
around 1955-56; I have not tried to award priority for the idea to any group in
particular.
34 Several of the researchers who at first failed to
grasp the idea of long-term pacing
had earlier worked with defibrillation, perhaps the quintessential example of an acute-
care technology; this experience dominated their perceptions of the pacemaker. Some
viewed the pacemaker almost as if it were a kind of defibrillator. See the discussion at
the "Rockefeller Conference," September 1958, as excerpted in Kirk Jeffrey, ed., "The
Conference on Artificial Pacemakers and Cardiac Prosthesis, 1958," PACE 16 (1993):
1445-82. Joel D. Howell found an analogous pattern in early constructions of the
meaning and utility of the ECG: Howell, "Early Perceptions of the Electrocardiogram"
(n. 9 above).

16. Pacing the Heart 597
unanticipated result, the new formulation also prepared the way for
a vast increase in the manufacture and use of pacemakers.
The idea for long-term pacing was "in the air"by about 1956, and
researchersdebatedits feasibilityat a one-dayconference in September
1958. Zoll explained that resuscitatingpatientsfrom Stokes-Adamsat-
tacksrepresentedno solutionto the underlyingproblemof heartblock;
in a vivid presentation,he made the case for fundamentallyredefining
the function of cardiac pacing: "Afterthe initial excitement of saving
the patient from the initialepisode of standstill,everybodyrelaxes and
you come back later ... and find the patient had another episode....
You can resuscitatea patient... if you are ready all the time for the
rest of the patient'slife, and that is a big order."35
Just such a situation arose in St. Paul, Minnesota, in March 1959,
when Samuel Hunter, a surgeon who had done a residency with Lil-
lehei, was presented with an unexpected case, a 72-year-old man in
complete heart block and suffering dozens of Stokes-Adamsattacks
daily. Rather than restartingthe heart time and again by means of an
external pacemaker,Hunter opened the patient'schest and sutured an
experimental bipolar pacing electrode, never before used with a hu-
man subject,to the ventricularmyocardium."The patientwasnot anes-
thetizedbut wasessentiallydead when we brought him to the operating
table,"Hunter later recalled. "Wejust kind of kept his heart going by
pounding his chest."Engineer Norman Roth attachedthe lead to one
of the new battery-poweredexternal pulse generators. "A lot of other
people were in the room, and when it startedIjust couldn'tbelieve my
eyes. Because it's one thing [to have] a nice little compact heart in a
child; but this was a 72-, 73-year-oldman with a big bulbous heart that
was kind of like a big jellyfish in there, sort of semi-blue; and all of a
sudden it startedto pump, vigorouslyand accordingto the rate that we
wanted, and we could control it, and all of a sudden he startsto wake
up! So we had to put him to sleep and finishthe operation. I don't know
what I said; someone said, 'My God, it worked!"'36 Hunter's patient
35Jeffrey, ed., p. 1450. The debates at this meeting are analyzed in Kirk Jeffrey,
"The Next Step in Cardiac Pacing: The View from 1958," PACE 15 (1992): 961-67.
Of Zoll's first fourteen pacing cases as reported in 1954, eight had died from later
Stokes-Adams attacks after an initial successful resuscitation via the pacemaker. See
Paul M. Zoll et al., "Treatment of Stokes-Adams Disease by External Electric Stimula-
tion of the Heart," Circulation 9 (1954): 482-92.
36Interview with Samuel W. Hunter, Mendota Heights, Minn., November 30, 1989.
Hunter also reported that the patient, Warren Mauston, would allow the surgeon
to turn off the external pulse generator to demonstrate its functioning for visiting
cardiologists. Mauston would slip into unconsciousness within a few seconds, "then I'd
snap it on again, and he'd come right out of it. I did that several times. I had a lot of

17. 598 KirkJeffrey
lived in good health for nine more years, dependent on his pacemaker
the entire time. A reporter wrote that "although he occasionally frets
at being unable to go out on the golf course as he used to, he putts on
the living-room rug..., gets up and downstairs and walks around the
neighborhood."37
This case, which had arisen as a clinical emergency rather than as
part of a research program, was one of several around 1959-60 to
demonstrate that it was possible to pace the heart over an extended
period and send the patient home.38 By 1959 several research teams
were already experimenting with new kinds of pacemakers that
would be more suitable for long-term use. Most of the new designs
contemplated an implanted, battery-powered pulse generator to elim-
inate a major source of infection, the pacing wire that came through
the patient's chest. A fully implanted device would also ensure that
the doctor retained complete control of the pacemaker by putting it
where the patient could not touch it. However, implanting the pulse
generator implied that the patient must undergo future surgical pro-
cedures when the battery ran low.
By now, research groups in the United States and Europe were
racing to come up with a practical long-term pacing device. Teams
in Stockholm and London implanted several pacemakers manufac-
tured by the Swedish firm of Elema-Shonander between 1958 and
early 1960. The Elema pulse generator was rechargeable by an induc-
tion coil placed on the patient's body. This device had technical prob-
lems, and in 1961 the company introduced a successor with mercury
cells. Around the same time, a group at Yale University experimented
with a radio frequency pacemaker that included an implanted re-
ceiver attached to the pacing electrodes, and an external transmit-
ter-a setup that exteriorized the battery.39
[ECG] tracings. I had those all over the laboratory-Mr. Mauston sliding toward eter-
nity because I'd turned off his pacemaker."
37Samuel W. Hunter et al., "A Bipolar Myocardial Electrode for Complete Heart
Block," Journal-Lancet 79 (1959): 506-8; David C. Schechter, "Background of Clinical
Cardiac Electrostimulation. VII. Modern Era of Artificial Cardiac Pacemakers," New
YorkStateJournal of Medicine 72 (1972): 1176-81; Spencer (n. 23 above); interview with
Hunter. The electrode was an experimental model developed by Norman Roth, an
engineer at Medtronic.
38Prior to Hunter's case, the longest episode of pacing had probably involved a
patient at Montefiore Hospital in the Bronx who had been intermittently pacemaker-
dependent (and hospital-bound, though ambulatory) for ninety-six days in the fall of
1958. See Seymour Furman and John B. Schwedel, "An Intracardiac Pacemaker for
Stokes-Adams Seizures," New England Journal of Medicine 261 (1959): 943-48. This
case is discussed below.
39A. H. M. Siddons and O'Neal Humphries, "Complete Heart Block with Stokes-
Adams Attacks Treated by Indwelling Pacemaker," Proceedings of the Royal Society of
Medicine 54 (1961): 237-38; Rune Elmqvist, "Review of Early Pacemaker Develop-

18. Pacing the Heart 599
In June 1960, at the Veterans Administration (V.A.) Hospital in
Buffalo, New York, an elderly man received the first successful fully
implanted pacemaker. Designed by electrical engineer Wilson
Greatbatch, it was implanted by William Chardack, a surgeon.40 The
Chardack-Greatbatch pacemaker, licensed to Medtronic and modi-
fied in various ways, quickly set the standard for cardiac pacemakers
in the United States. The first version to reach the market contained
only eight circuit components including two junction transistors. The
pulse generator, slightly larger than a pocket watch, encapsulated the
circuitry and a mercury-cell battery in silicone rubber. Devices of this
generation were known as asynchronous, fixed-rate pacemakers: they
had no capacity to sense electrical activity within the heart and could
not vary impulse rate or amplitude; they simply fired at a preset
rate such as 70 impulses per minute.41 But the Chardack-Greatbatch
pacemaker was a wonder for its time. After several early failures from
broken wires, Chardack designed a coiled-spring lead that proved
remarkably reliable.42 (See fig. 3.)
Inventing permanent cardiac pacing involved not only the device but
the surgical procedure. Implantation of a pacemaker in the 1960s qual-
ified as major surgery; it was Chardack who created the technique.
Working in an operating room on a fully anesthetized patient, the sur-
geon created a pocket beneath the skin in the patient's left abdomen as
a site for the pulse generator. He then made a large chest incision and
ment," PACE 1 (1978): 535-36; William W. L. Glenn et al., "Remote Stimulation of the
Heart by Radiofrequency Transmission," New England Journal of Medicine 261 (1959):
948-51. The "main line" of development, as described in the text, was pursued in
the late 1950s by Zoll, William Chardack, and other teams, with Chardack's group
announcing the first successful clinical case, an important symbolic milestone in the
eyes of physicians.
40William M. Chardack et al., "A Transistorized, Self-Contained, Implantable Pace-
maker for the Long-Term Correction of Complete Heart Block," Surgery 48 (1960):
643-54; Wilson Greatbatch, "Twenty-Five Years of Pacemaking," PACE 7 (1984):
143-47. The group employed hunt-and-try tactics to solve the two crucial problems
they encountered: protecting the battery and circuitry from body fluids while permit-
ting the diffusion of hydrogen gas, a by-product of the nickel-cadmium battery chemis-
try, and finding a lead system able to withstand approximately 31.5 million flexions
per year from the motion of the beating heart without breaking or causing a lesion in
the heart wall. Chardack's group did not learn of Ake Senning's work in Stockholm
until just before the first clinical use of their implanted pacemaker. See William M.
Chardack, "Recollections- 1958-1961," PACE 4 (1981): 592-96.
41The most complete review of these early pacemakers is William M. Chardack et al.,
"Clinical Experience with an Implantable Pacemaker," Annals of theNew YorkAcademyof
Sciences 111 (1964): 1075-92.
42William M. Chardack, "A Myocardial Electrode for Long-Term Pacemaking," An-
nals of the New YorkAcademyof Sciences 111 (1964): 893-906. The first patient, Frank
Henefelt, is interviewed in Spencer (n. 23 above).

19. 600 KirkJeffrey
FIG. 3.-The Medtronic5850, a Chardack-Greatbatch implantablepacemakerfrom
about 1963, showing the coiled-spring lead and myocardialelectrodes invented by
WilliamChardack. The pulse generatoris encapsulatedin siliconerubber.The "subcu-
taneous extension" on the left, known affectionatelyto implanters as the "pigtail,"
contained three wires and was positionedjust beneath the patient'sskin. Connecting
wire A to B via a small incision increasedthe pacemakeroutput; connecting B to C
disabled the pacemaker.(Photo courtesyof Medtronic,Inc.)
retracted the ribs to expose a portion of the left ventricular surface.
The surgeon drew the lead through a tunnel beneath the skin from
the pacemaker pocket to the heart, sutured the two electrodes to the
ventricular muscle, and plugged the lead into the pulse generator. Re-
placing a depleted pulse generator was simpler: the surgeon made a
small abdominal incision under local anesthetic, detached the genera-
tor from the lead, and substituted a new one.43
43William Chardack,"CardiacPacemakersand Heart Block,"in Surgery the
M. of
Chest,ed. John H. Gibbon,Jr., et al., 2d ed. (Philadelphia,1969), pp. 824-65, gives
details of surgical technique. By the mid-1960s it had become standard practice to
employ a temporarytransvenousendocardiallead (describedbelow) to maintainthe
heart rate before and during surgery for implantationof a permanent myocardial
pacemaker.Because of unexpectedlyrapid batterydepletion and occasionalwire fail-

20. Pacing the Heart 601
NoncompetitivePacing for IntermittentBlock
Until about 1965, permanent pacing of the heart had the character
of an experimental technology, with journals often publishing ac-
counts of unexpected crises such as broken wires and discussions of
possible alternativesto mercuricoxide cells as the power source. Some
practitionersalso became concerned that asynchronouspacing might
induce ventricularfibrillationin occasionalpatients who did not have
fixed complete heart block but intermittentblock with occasionalnor-
mally conducted beats. In such cases the ventricles might receive nat-
ural and artificialsignals in competition. A pacemakerimpulse deliv-
ered at the end of ventricular contraction could trigger VF; the
irritabilityof the heart muscle and hence the danger of VF appeared
greatest when the pacemakerfired into tissue damaged by an earlier
heart attack.44
Aware of the growing concern about pacemaker-inducedVF, the
biomedical engineer Barouh Berkovits, at American Optical Com-
pany, designed a sensing capability into the pacemaker so that it
would fire at a fixed rate, exactly as in an asynchronous pacer, but
would reset itself if it sensed the depolarization of the ventricles.45
ures, some early patientshad to endure a dozen or more implantprocedures.Clearly,
lead replacement entailed a much more severe procedure than replacement of the
pulse generator. The patient who had received Senning's implanted pacemaker in
1958, Arne Larsson,survivedwithout pacing for more than a year after the failure of
the initial device; he is still living and as of 1991 had had twenty-fivepacemakers:
letter from Larssonto author,June 25, 1991.
4Agustin Castellanos, et al., "RepetitiveFiring Occurringduring Synchronized
Jr.,
Electrical Stimulation of the Heart," Journal of Thoracic and CardiovascularSurgery 51
(1966): 334-40; MichaelBilitch et al., "VentricularFibrillationand CompetitivePac-
ing," New England Journalof Medicine (1967): 598-604; Leonard S. Dreifus et al.,
276
"The Advantagesof Demand over Fixed-RatePacing,"Diseases theChest (1968):
of 54
86-89; WilliamM. Chardacket al., "Pacingand VentricularFibrillation," Annalsof the
New York Academy Sciences (1969): 919-33. It had long been knownthat stimulat-
of 167
ing the ventriclesduring their "vulnerablephase"could induce fibrillation,but some
leading figures in the pacing field remained skeptical about the possibilityof pace-
maker-inducedVF because the pacemakerstimulus was so small and because direct
evidence was lacking. It was difficult to demonstrate conclusively that pacemaker-
induced VF had killed some patients unless their heart rhythmshad been monitored
at the moment of death. Interviewwith Barouh V. Berkovits,San Diego, California,
May 7, 1993.
45 the Berkovits
In pacemakerthe ventricularelectrode sensed the electricalindica-
tion of spontaneousventricularactivity(the R wave of the ECGtracing),and an ampli-
fier magnifiedthis signal.The amplifiedsignalreset the timing circuitso that the pacer
would not deliver another impulse until a preset interval,e.g., 850 milliseconds,had
elapsed. In early pacemakersof this sort, the intervalwas immutable,but beginning
in the 1970s it could be programmedby the physician.The Berkovits pacing mode
was later renamed "ventricular inhibited"because a sensed ventricularpulse inhibited

21. 602 KirkJeffrey
American Optical announced its new pacemaker (variously described
as a "ventricular inhibited" or a "demand" pacemaker) in 1965 and
within a few years had licensed other manufacturers to produce their
own devices capable of pacing "on demand." By 1969, four-fifths of
new pacemaker implants involved devices configured to avoid compe-
tition. Noncompetitive pacing had rapidly and completely superseded
the asynchronous mode.46
The invention of noncompetitive pacing is a richly instructive epi-
sode. Confronted with hundreds of pacemaker-dependent patients,
research cardiologists of the early 1960s had undertaken intense stud-
ies of heart block and other forms of slow heart rate. Once they began
to follow patients on pacemakers over intervals of many months, it
dawned on some that pacing had created a new cause of death, VF
resulting from pacemaker competition. The effort to account for
these deaths led cardiologists to the insight that some cases of com-
plete heart block were not fixed but could revert to intermittent block
with some normally conducted beats.47 Cardiologists had described
the problem of pacemaker competition in print, but it was the engi-
neer, Berkovits, who conceived of a way to solve it. He then invited
physicians' comments on the idea and their collaboration in clinical
trials. Earlier choices in the design of implanted pacemakers, accumu-
lated clinical experience with pacemaker-dependent patients, and in-
tensified research into disturbances of heart rhythms all contributed
to the medical framing of intermittent heart block and of the non-
competitive pacing mode.48
Partly in order to circumvent the Berkovits patent on ventricular
the pacer from firing. See George H. Myers and Victor Parsonnet, Engineering in the
Heart and Blood Vessels(New York, 1969), pp. 34-49; and Bryan Parker, "Pacemaker
Electronics," in Seymour Furman and Doris J. W. Escher, Principles and Techniquesof
Cardiac Pacing (New York, 1970), pp. 43-61.
46Louis Lemberg et al., "Pacemaking on Demand in AV Block," Journal of the Ameri-
can Medical Association 191 (1965): 106-8. Medtronic introduced its first ventricular
inhibited pacemaker in May 1967; a patent fight with American Optical ensued. The
acceptance of noncompetitive pacing by 1969 is reported in Victor Parsonnet, "The
Status of Permanent Pacing of the Heart in the United States and Canada," Annales
de cardiologieet d'angiologie 20 (1971): 287-91.
47See the discussion in Dreifus et al.
48One can carry the point further: the medical finding that legitimized noncompeti-
tive pacing depended for its authority on the prior acceptance of noncompetitive
pacing. Only after noncompetitive pacing had come into widespread use did compara-
tive mortality data provide firm corroborative evidence supporting the hypothesis that
patients on asynchronous pacers died more frequently than those on noncompetitive
pacers. Before noncompetitive pacing, it had been more of a suspicion. See the Berko-
vits interview (n. 44 above).

22. Pacing the Heart 603
inhibited pacing, the Cordis Corporation introduced a "ventricular
triggered" pacemaker. In this design, the device paced the ventricle
at a fixed rate; but a sensed ventricularcontraction,instead of inhib-
iting the pacemaker, triggered it to fire instantaneously and then
recycle. Delivered at a moment when myocardialcells had just depo-
larized and were refractory to another stimulus, the pacemaker im-
pulse did not compete with the heart's natural signal. The two sys-
tems, ventricular inhibited and triggered, were both widely used
during the late 1960s, but Berkovits'sinhibited mode eventually pre-
vailed because it caused less drain on the pacemaker battery and
because it seemed to emulate the "natural" escape mechanism of the
heart in which certain cells below the site of the block, capable of
spontaneously depolarizing but normally inhibited from doing so,
will eventually fire in the absence of a normallyconducted impulse.49
The TransvenousRoute
From a medical point of view, the distinctivefeature of pacing from
1960 on was its reliance on direct stimulation of myocardial tissue.
In order for the surgeon to attach the pacing electrode to the heart,
the patient had to undergo general anesthesia and surgical opening
of the chest. Since most patients were elderly men and women suffer-
ing from severe heart disease, hospital mortality rates in the early
and mid-1960s averaged about 7.5 percent.50
A group at Montefiore Hospital in the Bronx had already pio-
neered a second route to the heart, this one through a vein and
into the pumping chambers. In 1958, Seymour Furman, a first-year
surgicalresident at Montefiore,invented a catheter pacing lead, intro-
duced it via the vein at the inside of the elbow, and passed it through
49J. Walter Keller, Jr., "Evolution of Pacemaker Systems," in CardiacPacing: Proceed-
ings of theIVth InternationalSymposium CardiacPacing, ed. HilbertJ. T. Thalen (Assen,
on
1973), pp. 123-27. On the heart's "latent pacemakers," see Zipes, "Specific Arrhyth-
mias" (n. 18 above), pp. 685-86. Berkovits maintained that a biomedical engineer
should always strive to "follow nature-if you can learn from it, you'd better do it."
Triggered pacing departed from "the normal way of the heart" (Berkovits interview
[n. 44 above]). The belief that patients would be better off if treatment emulated
"normal physiology" was fundamental to the appeal of ventricular inhibited pacing
and later of dual-chamber pacing. Ironically, more "physiological" pacemakers also
proved to be more complex. For a general discussion of the appeal of the physiological,
see Joel D. Howell, "Cardiac Physiology and Clinical Medicine? Two Case Studies," in
Physiology in the American Context, 1850-1940, ed. Gerald L. Geison (Bethesda, Md.,
1987), pp. 279-92. See also Richard Sutton et al., "Physiological Cardiac Pacing," PACE
3 (1980): 207-19.
50Chardack, "Cardiac Pacemakers and Heart Block" (n. 43 above), p. 837, reporting
on a study from 1967 that had reviewed many large series.

23. 604 KirkJeffrey
FIG.4.-Pincus Shapiro at MontefioreHospital, fall 1958. The lower unit on the
cart is an ElectrodynePM-65pacemaker-defibrillator; restingatop it is an Electrodyne
monitor with a small oscilloscope.The pacing lead enters a vein at the inside of the
patient'sleft elbow.This apparatusplugged into a wall socket;the physician,Seymour
Furman,later substituteda car batteryand a converter.(Photocourtesyof Medtronic,
Inc.)
the venous system and the right atrium and into the right ventricle
of the patient's heart while observing its progress on a fluoroscope.
Not knowing of the Medtronic portable pulse generator, Furman had
connected the lead to an Electrodyne pulse generator that plugged
into the AC electrical system (fig. 4). This apparatus paced Furman's
second patient intermittently for ninety-six days and enabled the man
to walk up and down the hospital corridor; eventually, pacing was
discontinued, and the patient was able to leave the hospital and go

24. Pacing the Heart 605
home.51Over the next two years, Furmanand his coworkersreported
on dozens of additional cases of transvenous pacing.52
From the first, transvenous pacing could claim some significant
advantagesover the more invasivemyocardialapproach. Most impor-
tant, the physiciancould gain accessto a vein and introduce the cathe-
ter without subjecting the patient to major surgery. The technique
also reduced the risk of damage to the heart tissue because the pacing
electrode either floated free in the ventricle or barely touched the
ventricularwall.
Yet the transvenous route did not gain widespread acceptance for
long-term pacing in the United States until the late 1960s. Furman's
youth and relative lack of renown may have been a factor initially;
his removal from the scene for two years' military duty definitely
slowed the development phase of transvenous pacing. There were
early reports of intermittent failure to pace and of the catheter's
perforating the vein. Some time elapsed before a standard technique
emerged: those interested in transvenous pacing tried several veins
before settling on one just beneath the collarboneas the most suitable
for introduction of the catheter. More broadly, cardiac catheteriza-
tion was a technique more familiar to cardiologiststhan to surgeons;
indeed, use of the catheter as a diagnostictool was perhaps the defin-
ing ritual of cardiology. Because of the leadership of surgeons like
Lillehei and Chardack,the medical world had grown accustomed to
the idea of pacemaker implantationas a surgicalprocedure.53
Transvenous pacing spread rapidly after about 1965. The transve-
nous route first came into use during the early 1960s as a means of
temporary pacing during surgery to implant a myocardial pace-
maker; their experience with temporary transvenous pacing helped
51This case, one of the most dramatic and influential in the history of pacing, was
reported in Furman and Schwedel, "An Intracardiac Pacemaker" (n. 38 above). See
also "Electrode in Heart Saves Man's Life," New YorkTimes (November 27, 1958), p.
36.
52See, e.g., Seymour Furman et al., "The Use of an Intracardiac Pacemaker in the
Control of Heart Block," Surgery 49 (1961): 98-108, and "Transvenous Pacing: A
Seven-Year Review," AmericanHeart Journal 71 (1966): 408-16; and Victor Parsonnet
and Alan D. Bernstein, "Transvenous Pacing: A Seminal Transition from the Research
Laboratory," Annals of ThoracicSurgery48 (1989): 738-40.
53Seymour Furman et al., "Implanted Transvenous Pacemakers: Equipment, Tech-
nic and Clinical Experience," Annals of Surgery 164 (1966): 465-74; Howell, "Changing
Face of Twentieth-Century American Cardiology" (n. 8 above); Donald Baim and
Richard J. Bing, "Cardiac Catheterization," in Cardiology:The Evolution of the Science
and the Art, ed. Richard J. Bing (Chur, 1992), pp. 1-28.

25. 606 KirkJeffrey
accustom surgeons to the techniques of catheterization.54 Reports
from Europe of successful long-term transvenous pacing and the in-
troduction of a flexible transvenous lead in 1965 (a variant on Char-
dack's coiled-spring design) contributed to a shift toward the transve-
nous technique. Perhaps the clinching factor proved to be doctors'
growing realization that the transvenous procedure was less risky for
their elderly patients. Hospital mortality rates from transvenous pac-
ing were 0-3 percent.55 Indeed, Chardack himself began to use the
transvenous route. By 1970, experienced implanters had switched in
large numbers to transvenous pacing, while new entrants to the field
were accepting it as the normal path to the ventricle.56 Today virtually
all pacing leads are introduced transvenously and stimulate the heart
from within. The patient remains conscious throughout the proce-
dure, now typically an hour or less in duration.57
Pacing in the 1960s: Treatment ChronicDisease
for
Cardiac pacing spread rapidly in the 1960s, nicely exemplifying
the "desperation-reaction" model of technological diffusion: when a
disease is life-threatening and no existing therapy seems to help, doc-
tors will adopt a promising new therapy-particularly when the re-
sults are quick, dramatic, and easy to interpret-even before the de-
velopment phase for the therapy has run its course.58 By the end of
the decade, the number of primary (first-time) implant procedures
54William M. Chardack, "Heart Block Treated with an Implantable Pacemaker,"
Progress in CardiovascularDiseases 6 (1964): 507-37, at 517; Editorial, "'Intravenous'
Cardiac Pacemaking," Journal of the American Medical Association 184 (1963): 582-83;
I. Richard Zucker et al., "Dipolar Electrode in Heart Block," Journal of the American
Medical Association 184 (1963): 549-52.
55
Rodney Bluestone et al., "Long-Term Endocardial Pacing for Heart-Block," Lancet
2 (1965): 307-12; Hans Lagergren et al., "One Hundred Cases of Treatment for
Adams-Stokes Syndrome with Permanent Intravenous Pacemaker," Journal of Thoracic
and CardiovascularSurgery 50 (1965): 710-14. On mortality rates, see Chardack, "Car-
diac Pacemakers and Heart Block" (n. 43 above), p. 837.
56Parsonnet, "Status of Permanent Pacing" (n. 46 above), p. 289. Parsonnet's pace-
maker team at Newark Beth Israel Medical Center in Newark, New Jersey, had gone
from six permanent transvenous pacemakers out of thirty-one implants in 1964 to
twenty-four out of thirty in 1965.
57In the early 1970s, manufacturers introduced kits to assist the physician with
transvenous lead manipulation. The kit includes a stylus through which a temporary
guide wire and then the lead itself are introduced to the vein and advanced into the
heart. The procedure can be more time-consuming if leads are to be introduced to
both atrium and ventricle. On the transvenous technique, see Sutton and Bourgeois
(n. 5 above), pp. 177-234.
58Kenneth E. Warner, "A 'Desperation-Reaction' Model of Medical Diffusion,"
Health ServicesResearch 10 (1975): 369-83; H. David Banta, "Embracing or Rejecting
Innovations: Clinical Diffusion of Health Care Technology," in The Machine at the

26. Pacing the Heart 607
was approaching twenty thousand per year in the United States, while
primary and replacement implants combined were nearing fifty thou-
sand per year (table 1). Within this overall picture of rapid adoption,
pacing underwent so many technological and procedural changes in
the 1960s that even speaking of the decade as a single era may appear
to strain logic. Yet all the innovations were introduced in furtherance
of a clear, overriding goal: to create a prosthetic device that would
permanently manage a heart in complete block.
To all appearances, both the pacemaker and the procedure for
implanting it had stabilized by 1970: the standard pacing device of
that era was a fully implanted, ventricular inhibited pacemaker that
stimulated the inner surface of the ventricle via a transvenous lead.
In nearly all cases, this apparatus ministered to a patient whose symp-
toms included ventricular bradycardia, dissociation of the atria and
ventricles, and dizziness or blackouts-the symptoms of heart block.
Despite the rapid acceptance of transvenous pacing, the typical im-
planter of the 1960s and early 1970s remained a surgeon and the
central ritual in the field of cardiac pacing remained the act of im-
planting the pacemaker in a hospital operating room.59
The practice of pacing reflected the procedure-oriented character
of American medicine. Throughout the 1960s, surgeons and device
manufacturers were the principal sponsors of pacing development.
Since the standard implantation technique of the early 1960s entailed
exposure of the myocardial surface of the heart, pacing was dissemi-
nated in tandem with heart surgery itself, proceeding generally from
core institutions (large medical centers often affiliated with medical
schools) to the periphery (doctors in private practice with privileges
at general hospitals).60
Bedside, ed. Stanley Joel Reiser and Michael Anbar (New York, 1984), pp. 65-92;
Thomas P. Hughes, "The Development Phase of Technological Change," Technology
and Culture 17 (1976): 423-31. The implantable pacemaker appears to be a case in
which innovation (the introduction of the technology into the marketplace and its
diffusion into widespread use) proceeded simultaneously with development. This pat-
tern would be highly unlikely in a new life-sustaining medical device today because
the Food and Drug Administration, under the Medical Device Amendments of 1976
and the Safe Medical Devices Act of 1990, would refuse to license the device for
general use until extensive clinical trials had been conducted.
59Victor Parsonnet found that, in 1972, about seven implanters in ten were surgeons:
"A Survey of Cardiac Pacing in the United States and Canada," in Thalen, ed. (n. 49
above), pp. 41-48.
60Pacemaker manufacturers estimated in the early 1970s that between one-quarter
and three-fifths of implanting physicians treated fewer than five new patients per year:
Parsonnet, "Survey of Cardiac Pacing," p. 42. See also Parsonnet, "Status of Permanent
Pacing" (n. 46 above), p. 287; and Daniel M. Fox, Health Policies, Health Politics: The
British and AmericanExperience, 1911-1965 (Princeton, N.J., 1986), p. 210 and passim.

27. 608 KirkJeffrey
Chardackof the V.A. Hospital in Buffalo was the pivotal medical
figure in these years: Chardack'sannouncement of the first clinically
effective implant in 1960, his invention of the coiled-springelectrode
in 1962, and his meticulous analyses of his group's successes and
failures galvanized others to try cardiac pacing. Chardack and his
associate,engineer WilsonGreatbatch,worked closely with the manu-
facturing firm Medtronic in Minneapolis. For nearly a decade, all
Medtronic pulse generators bore the "Chardack-Greatbatch" brand
name. The team from Buffalo were "key consultants"to the firm,
overseeing its implantablepacemakerprogram and keeping in touch
with clinicians around the United States.6' But Medtronic was by no
means the only firm to introduce a "permanent"pacemaker in the
early 1960s. Sooner or later, each of the medical research teams that
were actively at work on pacemakerdevelopment established a rela-
tionship with a device manufacturer.62 Medtronicmaintainedits mar-
ket dominance partly through its technological head start but also
because of its preexisting reputation with medical equipment, its con-
tacts with surgicalgroups, and its associationwith pioneers in cardiac
pacing such as Lillehei, Bakken, Chardack,and Greatbatch.63 the In
fast-developingpacing industry, the firm by mid-decade had assumed
the role of industry leader even though its first pacemakerdated back
only to 1958.
For a number of reasons, the barriersto entry remained quite low
in the pacemaker industry throughout the 1960s. Federal require-
ments for expensive and time-consumingcontrolled clinical trials to
assess the safety and efficacy of life-sustaining medical devices did
not come into existence until 1976. Though manufacturerssecured
patent protection for some devices and components, many of the key
components of early pacemakers such as batteries, wires, and the
biocompatible silicone-rubber encapsulation for a pulse generator
were standard products purchased from other manufacturers;other
components, notablythe blocking-oscillator pacing circuitof the early
implantables,were in the publicdomain. Newer entrantsto the indus-
try commonly sought market share by introducing elements of tech-
61Bakken interview (n. 32 above).
62All of the
early devices are described by their inventors in William W. L. Glenn, ed.,
"Cardiac Pacemakers," Annals of theNew YorkAcademyof Sciences 111 (1964): 813-1122.
63Creative Strategies, Inc., "Medical Electronics" (Palo Alto, Calif., 1973), copy at
Medtronic Library, Fridley, Minnesota; Jerry Flint, "Medtronic: Medicine, Electronics
and Profit," New YorkTimes(April 4, 1976), sec. 3, pp. 1, 9; Daniel R. Denison, Corporate
Culture and OrganizationalEffectiveness (New York, 1990), pp. 95-108. The principal
large corporation to introduce a line of pacemakers was General Electric, but its devices
did not win widespread acceptance; GE withdrew from pacing in 1977.

28. TABLE 1
GROWTH OF CARDIAC PACING IN THE UNITED STATES
Population 65 Ye
Estimated Total Implants and Older
Estimated Primary Implants (Replacements Included) (in Millions)
Year (1) (2) (3)
1960-64 ................... 2,500 5,000 ....
1965 ......................... 2,900 5,700 18.2
1967 ......................... 8,250 15,000 18.8
1969 ......................... 16,000 27,000 19.5
1972 ......................... 25,000 45,000 19.9
1975 ......................... 57,000 90,000 22.7
1978 ......................... 69,000 100,000 24.1
1981 ......................... 118,000 142,000 26.3
M.
SouRcEs.-My estimates for the pacemaker implant data (cols. 1 and 2) are based on data given in William
William Char
Experience with an Implantable Pacemaker: An Appraisal," Surgery 58 (1965): 915-22, at 915;
Implantable Pacemaker: Past Experience and Current Developments," in Resuscitation and Cardiac Pacing, e
Thomas J. Thomson (Philadelphia, 1965), pp. 213-49, at 246; Victor Parsonnet, "The Status of Permanent Pac
and Canada," Annales de cardiologie et d'angiologie 20 (1971): 287-91, at 288, and "A Survey of Cardiac Pacing i
CardiacPacing: Proceedings of the IVth International Symposiumon Cardiac Pacing, ed. HilbertJ. T. Thalen (Assen, 1
Victor Parsonnet, "World Survey on Cardiac Pacing," PACE 2 (1979): W1-W17, at W3; Victor Parsonnet, Candice
"The 1981 United States Survey of Cardiac Pacing Practices,"Journal of the American College of Cardiology3 (1984)
estimates of pacemaker sales. Population data (col. 3) are from U.S. Bureau of the Census, Statistical Abstracto
various years).
= (col. 1 x 80%)/col. 3
*Approximately 80 percent of pacemaker patients are age 65 and older. Thus, col. 4

29. 610 KirkJeffrey
nological novelty. American Optical's "demand" and Cordis's "trig-
gered" pacemakers were outstanding examples.
The discovery and analysis of pacemaker competition and Berko-
vits's invention of a pacing mode that could reliably sense and re-
spond to cardiac activity pointed to emerging new relationships
among laboratory research, doctors' clinical experience, and corpo-
rate research and development. It was clear, first, that the growing
clinical use of pacing had encouraged a great deal of new research
into the precise nature of various heart conduction disorders that
produced arrhythmias.64 As cardiologists gained new understanding
of these disorders, advances in microcircuitry and other pacemaker
components permitted manufacturers to introduce new pacing
modes suitable for managing them.65 During the decade of the 1960s,
the locus of inventive activity shifted away from the laboratories of
physician-inventors such as Zoll, Chardack, and Furman to the medi-
cal device firms.
The invention and spread of pacing in the 1950s and 1960s coin-
cided with the postwar growth of prepaid hospital insurance. A re-
sponse to the growing use of expensive technology in hospitals, insur-
ance tended to reduce cost constraints on doctors and hospitals by
creating a situation in which none of the three direct parties to the
medical transaction-care provider, patient, and hospital-had a
pressing interest in economizing. As Rosemary Stevens remarks,
64Pacing engendered a great deal of interest in the physiology of the conduction
system and the mechanisms of cardiac arrhythmias. For example, the number of arti-
cles on the heart conduction system published in American medical journals and listed
in Index Medicus rose tenfold between the years 1950-54 and 1963-67, from thirteen
to 129. A similar increase occurred in publications on heart block and related topics.
The pacemaker itself became a tool in the analysis of arrhythmias. The technology of
His-bundle electrocardiography, first reported in 1969, entailed atrial pacing. Invasive
cardiologists employ catheter electrodes to record intracardiac electrical activity at vari-
ous sites and may pace the atrium in the process; electrophysiologists overdrive the
heart with a pacemaker to test its propensity to go into sustained tachycardia or VF. See
Benjamin J. Scherlag et al., "Catheter Technique for Recording His Bundle Activity in
Man," Circulation 39 (1969): 13-18; Scherlag, "The Development of the His Bundle
Recording Technique," PACE 2 (1979): 230-33; Parsonnet and Bernstein, "Transve-
nous Pacing" (n. 52 above); Douglas P. Zipes, "The Contribution of Artificial Pacemak-
ing to Understanding the Pathogenesis of Arrhythmias," AmericanJournal of Cardiology
28 (1971): 211-22; William Grossman, "Cardiac Catheterization," in Braunwald, ed.,
Heart Disease (n. 18 above), pp. 180-203.
65Pacemaker circuitry is a large subject that I have chosen to avoid in this article.
For brief introductions from the period examined here, see R. D. McDonald, "The
Design of an Implantable Cardiac Pacemaker," Medical and Biological Engineering 4
(1966): 137-52; Myers and Parsonnet (n. 45 above), pp. 181-91; and Parker (n. 45
above).

30. Pacing the Heart 611
"hospital expenditures and reimbursement mechanisms drove each
other, in an expansionary spiral." By 1960, about two-thirds of the
American public enjoyed coverage under some type of private hospi-
tal insurance; but the remaining third, including the elderly, lacked
insurance and often found that the cost of hospital care was outdis-
tancing their ability to pay out of their own pockets.66
In the aftermath of the Democratic landslide of November 1964,
a broad coalition of interest groups-organized labor, various indus-
trial associations, Blue Cross and the private health insurance indus-
try, hospitals, and the American Association of Retired Persons
(AARP)-was finally able to persuade Congress to create a federal
program that would cover most costs of hospitalization and doctors'
fees for Americans over age sixty-five. The 89th Congress passed the
Medicare Bill, and President Lyndon Johnson signed it into law on
July 30, 1965.67 Beginning on July 1 of the following year, the federal
government through the Medicare program began to pay costs associ-
ated with pacemaker implantation and follow-up in patients aged
sixty-five and older, or about four-fifths of the pacemaker patient
population.68 Medicare Part A (hospital insurance) paid for the pace-
maker itself and for hospital services and procedures including
workup and the primary or replacement implantation procedure.
Medicare Part B covered 80 percent of physicians' fees, outpatient
follow-up care, and subsequent office visits to check on the pacer's
performance.
By guaranteeing payment of "reasonable and customary" charges,
Medicare greatly reduced the cost of cardiac pacing for the elderly
patient, provided no incentive for the hospital or the doctor to elect
not to implant a pacer in marginal cases, and signaled that care pro-
viders need not be greatly concerned about economizing in the choice
of hardware.69 This is not to imply that cardiac pacing was a tremen-
dously costly treatment. Successive generations of hardware and the
66Stevens, In Sicknessand in Wealth (n. 28 above), pp. 256-67, at 257.
67Judith M. Feder, Medicare: The Politics of Federal Hospital Insurance (Lexington,
Mass., 1977); Starr, Social Transformation 28 above), pp. 363-78; Fox, Health Policies,
(n.
Health Politics (n. 60 above), pp. 201-6.
68In the 1970s, the mean age of pacemaker patients at first implant was about sev-
enty-two: Seymour Furman, "Controversies in Cardiac Pacing," CardiovascularClinics
8 (1977): 313.
69Starr, Social Transformation(n. 28 above), pp. 374-78, 383-88; Stevens, In Sickness
and in Wealth, pp. 281-83; Edward D. Berkowitz, America'sWelfare Statefrom Roosevelt
to Reagan (Baltimore, 1991), pp. 166-80. Martin Feldstein, The Rising Cost of Hospital
Care (Washington, D.C., 1971), was one of many observers to point out that private
health insurance and Medicare contributed to increased demand for hospital services
by effectively reducing the cost to the average elderly person.

31. 612 KirkJeffrey
advent of new implant techniques in fact substantially reduced the
cost per patient between 1965 and 1975.70 But Medicare provided an
immense encouragement for the further spread of cardiac pacing.
Between 1967 and 1972, the number of first-time implants tripled
(see table 1), and overall expenditures on cardiac pacing soared. One
can reasonably conclude that policymakers and the public had in-
tended this result since Medicare so clearly encouraged the accep-
tance and use of new medical devices and procedures.
Sick Sinus Syndromeand Dual-ChamberPacing
Cardiac pacing has repeatedly undergone rapid and radical trans-
formations; in the early 1970s, the assumptions and standard prac-
tices of just a few years earlier again came up for renegotiation as
cardiologists once again expanded the list of indications for pacing.
As late as 1968, almost all pacemakers had been implanted to manage
fixed or intermittent heart block.71 But beginning in that year,
cardiologists framed a new conduction disease, the sick sinus syn-
drome (SSS). This term lumped together several disturbances of
heart rhythm involving a default of the sinus node, the source of the
electrical impulses that trigger atrial and then ventricular contrac-
tion-the heart's natural pacemaker. Within a few years, doctors were
implanting nearly as many pacers for SSS as for heart block.72
Sick sinus syndrome had a diverse list of symptoms. Doctors
learned that the condition might manifest itself as persistent and no-
ticeable slowdown of the firing rate of the sinus node, an inadequate
rate response to increases in the person's activity level, or sinus slow-
down associated with an excessively rapid atrial rate. All these mal-
functions could begin episodically but then later become fixed. In
more severe forms, the impulse might fail to spread beyond the sinus
node. Deprived of their normal signal from the sinus node, the atria
70Russell (n. 27 above), pp. 133, 156, and passim.
71At a pacing conference held in November 1968, virtually every paper assumed
that heart block was the sole indication for permanent pacing: Seymour Furman, ed.,
"Advances in Cardiac Pacemakers," Annals of the New York Academy of Sciences 167
(1969): 515-1075.
72J.Thomas Bigger, "Sick Sinus Syndrome Label for Many Cardiac Problems,"Jour-
nal of the AmericanMedical Association239 (1978): 597. M. Irene Ferrer, "The Sick Sinus
Syndrome in Atrial Disease," Journal of the American Medical Association 206 (1968):
645-46, offered the first formal definition of the condition with an extensive set of
indications. For background on the diagnosis, see Louis J. Acierno, The History of
Cardiology (London and New York, 1994), pp. 353-54. On the medical and social
framing of disease, see Charles E. Rosenberg, "Framing Disease: Illness, Society, and
History," in Framing Disease: Studies in Cultural History, ed. Charles E. Rosenberg and
Janet Golden (New Brunswick, N.J., 1992), pp. xiii-xxvi.

32. Pacing theHeart 613
might fibrillatetransientlyor continuously;the ventriclesmight adopt
a slow rate of contraction dissociated from the atria and eventually
come to a halt.
As long as episodes of SSS remained intermittent, the patient typi-
cally experienced few or no symptoms. But as sinus failure grew
more severe, patients suffered dizziness, fatigue, transient blackouts,
kidney failure, congestive heart failure, and pulmonary edema. All
of these resulted from the heart's inability to pump normally. Most
of the symptoms, however, were not unique to SSS and could vary
greatly from one patient to another. The same patient could manifest
a range of symptoms from one office visit to the next, and some
patients showed no clear symptoms at all except for slight irregulari-
ties in the ECG tracing.73Because of the erratic course of the "dis-
ease," diagnosing a failing sinus node could be difficult, especially in
its early stages.
Some of these abnormalitieshad been described decades earlier,
but the sinus node had come in for renewed attention in the early
1960s. The community of cardiac pacing specialistsbegan to pay at-
tention to the syndrome at the end of the decade, after they had
resolved earlier uncertainties about pacing for heart block.74They
learned that sinus node disorders, though often difficult to diagnose,
were not rare. There also seemed general agreement in the early
1970s that most such disorders did not present the same danger of
sudden death as did complete heart block.75
From the time the term "sicksinus syndrome"appeared in print,
cardiac pacing seemed the therapy of choice for its long-term man-
agement. Precisely because "the exact progress and timing of the
73M. Irene Ferrer, The Sick Sinus Syndrome(Mount Kisco, N.Y., 1974), pp. 91-93;
David B. Shaw, "The Etiology of Sino-Atrial Disorder (Sick Sinus Syndrome)," American
HeartJournal 92 (1976): 539-40; William J. Scarpa, "The Sick Sinus Syndrome," Ameri-
can HeartJournal 92 (1976): 648-60; Henri E. Kulbertus, "Experience with Permanent
Pacing in the Sick Sinus Syndrome," CardiovascularClinics 14 (1983): 189-94; Zipes,
"Specific Arrhythmias" (n. 18 above), p. 677.
74For a recent review of the literature, see Antonio Raviele and Francesco Di Pede,
"Sick Sinus Syndrome: Modern Definition and Epidemiology," in Proceedings of the
International Symposiumon Progress in Clinical Pacing, ed. M. Santini et al. (Amsterdam,
1990), pp. 279-88.
75On the
difficulty of diagnosis, see Ferrer, "Sick Sinus Syndrome in Atrial Disease."
The principal exception to the generalization that sinus node disorders did not present
imminent danger to the patient was fixed sinus arrest, a condition that Ferrer consid-
ered the end stage in a progressive disease (Ferrer, Sick Sinus Syndrome,p. 117). As
noted above, however, not everyone defined SSS as a single disease entity with a more
or less predictable course. Later research identified several sequelae that could be quite
serious: Kulbertus, p. 188.

33. 614 KirkJeffrey
complications of [SSS] are still unknown in great detail," it seemed
prudent to "consider installing a pacemaker, for safety's sake, in the
near future." According to the leading expert on sinus node disease,
the clinician "need not wait" for symptoms "to be intolerable"; as
soon as "symptoms of any note" appeared, "a pacemaker had best
be installed." Indeed, she added, "periodic or sustained SB [sinus
bradycardia] can no longer go unchallenged, even if asymptomatic."76
These statements opened the way for a rapid and substantial expan-
sion of cardiac pacing by adding a large new class of arrhythmias to
those already managed on pacemakers and by redefining the pace-
maker as a prophylactic device, insurance against possible (but unpre-
dictable) future deterioration in a patient's condition.77
Pacing for SSS came on with a rush in the early 1970s.78 By mid-
decade, at least one-third and perhaps 40 percent of the primary
pacemaker implantations in the United States were being carried out
to manage the condition. This new indication for pacing coincided
with a growth of about 125 percent in the number of new implants
between 1972 and 1975.79 It is not difficult to account for the rapid
76Ferrer, Sick Sinus Syndrome,pp. 97, 100, 107 (italics added). See also Michael Bilitch,
"Sick Sinus Node Syndrome," in Modern Cardiac Pacing: A Clinical Overview, ed. Sey-
mour Furman and Doris J. W. Escher (Bowie, Md., 1975), pp. 40-44; and Hilbert
J. T. Thalen, "Cardiac Pacing in Sick Sinus Syndrome," in To Pace or Not to Pace?
ControversialSubjects in Cardiac Pacing, ed. Thalen and J. Warren Harthorne (The
Hague, 1978), pp. 61-72.
77In another discussion Ferrer qualified this statement: if the sinus node was "slug-
gish, but not dangerous, . . . for these patients it would not be fair to implant a
pacemaker." See M. Irene Ferrer, "Pacing and Sick Sinus Syndrome" (Part 2; interview)
MedtronicNews 6 (1976): 3-4, 4.
78L. F. Silverman et al., "Surgical Treatment of an Inadequate Sinus Mechanism by
Implantation of a Right Atrial Pacemaker Electrode,"Journal of Thoracicand Cardiovas-
cular Surgery 55 (1967): 264-70, is an early case report of pacing for sinus node disor-
der; see also John W. Lister et al., "Electrical Stimulation of the Atria in Patients with
an Intact Atrioventricular Conduction System," Annals of the New YorkAcademyof Sci-
ences 167 (1969): 785-806.
79In the first of his repeated surveys of cardiac pacing practice in the United States,
published late in 1971, Parsonnet did not inquire about SSS or about pacing modes
other than asynchronous and ventricular inhibited. Two years later, Parsonnet re-
ported that fewer than half of the new pacemaker patients in the United States had
complete heart block, while more than half had presented with "sinus arrest" and
other symptoms of SSS: Parsonnet, "Status of Permanent Pacing" (n. 46 above), p. 288,
and "Survey of Cardiac Pacing" (n. 59 above), p. 43. Another cardiologist informally
estimated that in 1976, 40 percent of new implantations were for sinus node problems:
see Bigger (n. 72 above). Survey data from 1978-79 revealed that various forms of
sinus node disease were the indications for 40.4 percent of new implants in the United
States, while various forms of heart block accounted for 49.3 percent: B. S. Goldman
and Victor Parsonnet, "World Survey on Cardiac Pacing," PACE 2 (1979): W1-W17,
at W7.