Teo Te Wei - Pacing the Heart
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Teo Te Wei - Pacing the Heart Teo Te Wei - Pacing the Heart Document Transcript

  • Pacing the Heart: Growth and Redefinition of a Medical Technology, 1952-1975Author(s): Kirk JeffreySource: Technology and Culture, Vol. 36, No. 3 (Jul., 1995), pp. 583-624Published by: The Johns Hopkins University Press on behalf of the Society for the History of TechnologyStable URL: http://www.jstor.org/stable/3107242 .Accessed: 28/08/2011 20:07Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jspJSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org. The Johns Hopkins University Press and Society for the History of Technology are collaborating with JSTOR to digitize, preserve and extend access to Technology and Culture.http://www.jstor.org
  • Pacing the Heart: GrowthandRedefinition a MedicalTechnology, of1952-1975KIRK JEFFREY A cardiac pacemaker delivers electrical impulses to the heart so asto coordinate the pumping action of the upper and lower chambers(atria and ventricles) and speed the heart up from standstill or anunduly slow rate. Between 1952 and the mid-1970s, the practice ofcardiac pacing grew from "promising report" to "standard proce-dure" and then kept on growing.2 The earliest devices stimulated theheart from outside the patients body, but implanted pacemakersmade their appearance at the end of the 1950s. The number of pa-tients relying on pacemakers in the United States expanded to morethan 150,000 by 1975.3 In the 1990s, estimating conservatively,500,000-600,000 Americans carry pacemakers; more than 110,000pacemakers are implanted annually in the United States by about DR. JEFFREY is professor of history at Carleton College. He thanks Carleton Collegefor research support through the Faculty Development Endowment. Professor CliffordE. 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 rapidheart rates (tachycardia) and random electrical behavior with consequent loss of orga-nized beats (fibrillation). My definition of the pacemaker is time bound: as VictorParsonnet and Alan D. Bernstein have observed, "The definition of a pacemaker isimprecise, because now that word is applied to electrical stimulators that treat eitherslow or fast rhythms. In this computer age, a pacemaker is essentially an implantedmicrocomputer that can be adapted noninvasively to any type of stimulation or sensingthat is required." See Victor Parsonnet and Alan D. Bernstein, "Cardiac Pacing after25 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 astherapeutically, but this article limits its scope to therapeutic uses of pacing. 2John B. McKinlay, "From Promising Report to Standard Procedure: Seven Stagesin the Career of a Medical Innovation," Milbank Quarterly59 (1981): 374-411. 3Victor Parsonnet and Marjorie Manhardt, "Permanent Pacing of the Heart: 1952to 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
  • 584 KirkJeffrey8,000 physicians.4Pacing-related hardware, facilities, and serviceshave cost Medicarewell over $1 billion annually in recent years.5 A symbol in its early years of the fabulous promise of medicaltechnology, pacing in the early 1980s became a lightning rod fordoubts and concerns about the American system of health care. To-day, in a time of national debate about the cost and distribution ofhealth care, a review of a success story involving high-tech medicinemay help us understand one important underlying dynamic in thehealth-care system: the reciprocal and interactive process by whichtechnological change and new concepts of disease stimulate eachother, thereby creating a powerful momentum for growth. A technologicaldevice drawsus towardthe outlook and aspirationsof its sponsors, the groups that introduced it and shape its ongoingdevelopment and social meaning.6Hence, this articlespeaks of pacing 4Becauseno national pacemakerregistryexisted during the period covered by thisarticle, these and other figures must be taken as approximations.Here I follow theestimates of Parsonnet and his associates,who have conducted national surveys ofpacing practicesevery few years since 1971: Alan D. Bernstein and Victor Parsonnet,"Surveyof CardiacPacingin the United Statesin 1989,"American Journalof Cardiology69 (1992): 331-38. Their figure of 110,500 pacemakersimplantedin 1989 (apparentlymisprintedas 117,000) included 89,445 primary(first-time)implantationsand 21,055replacements.But another set of observerssuggests a figure of 250,000 implantationsper 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 dischargesfollowing the implantationof pacemakersin 1986-a suspiciouslylow number. Evenso, considering that the likely cost of pacing over the remaining life of an elderlyperson ran to at least $30,000 in the late 1980s, then an annual cohort of 60,000Medicarepacemakercandidateswould represent future direct pacing-relatedcosts ofsome $1.8 billion (U.S. Health Care FinancingAdministration, Office of Researchand Demonstrations, Health Care Financing: Special Report: Hospital Data by GeographicAreafor Aged Medicare Beneficiaries:SelectedProcedures, 1986 [Baltimore, June 1990], 2:77).Indirect costs to the health-caresystem are much more difficult to estimate. On theone hand, because they live longer, people carryingpacemakersincur other medicalcosts 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, andat a greatly reduced risk of cardiac arrest with its attendant emergency procedures(cardiopulmonary resuscitation,ambulance,intensivecare) or of majorfracturesfromfalls. For a general discussionof the cost-effectivenessof cardiacpacing, see RichardSutton and Ivan Bourgeois, Foundations of Cardiac Pacing, Part I (Mount Kisco, N.Y.,1991), pp. 303-13. 6CompareSusan E. Bells remarkthat a technology is "the product or embodimentof human activity":SusanE. Bell, "ANew Modelof MedicalTechnologyDevelopment:A Case Study of DES," Researchin the Sociologyof Health Care 4 (1986): 1-32, at 2. Onthe concept of sponsorship,see Ron Westrum,Technologies Society and (Belmont,Calif.,1991), pp. 171-93.
  • Pacing the Heart 585more 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, medicalunderstanding of heart arrhythmias, the rise of the medical-devicemanufacturing industry, and the policies of governments toward theconsumption of pacing devices and services. It is not an exclusivelyAmerican story: research and inventive activity in western Europe,Canada, and Japan have contributed in important ways to the growthand 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 cardiacpacing, 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 ofpacing 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 AmericanSociety 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,"Trainingin Cardiac Pacing," Journal of the American College of Cardiology 7 (1986): 1213-14;Seymour Furman, Editorial:"Certificate Special Competence in Cardiac Pacing," ofPACE 9 (1986): 1; Victor Parsonnet, "CardiacPacing as a Subspecialty," AmericanJournalof Cardiology (1987): 989-91. The leadingjournal in the field, PACE,was 59founded in 1978. 8An arrhythmiais a deviation from normal heart rhythm. I use the terms doctorand physicianas synonymsreferring to persons holding the M.D. degree and licensedto 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 formallycreated as a subspecialtyof internal medicine in 1940. Cardiologistsattend to diseasesof 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 medicalspecializationin the United States; see also Joel D. Howell, "The Changing Face ofTwentieth-Century American Cardiology,"Annals of InternalMedicine105 (1986):772-82.
  • 586 KirkJeffreywho 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 whenPaul M. Zoll announced his external pacemaker in 1952.10 Doctorsunderstanding of "cardiac pacing" repeatedly changed as medicalresearchersrepeatedly framed new heart arrhythmiasfor which pac-ing has seemed the appropriate therapy. Knowledge gained in thelaboratorywas passed to clinicianswho, in turn, informed biomedicalengineers of new needs and opportunities for pacing that requirednew pacing hardware.1lThe very success of clinical cardiac pacingstimulated further basic research into conduction disorders of theheart, bringing the process of transmissionof knowledge full circle. This account of the invention of effective heart pacemakers andthe development of pacing as a practicaltherapy thus asks what car-diac pacing has meant, principallyto the surgeons and cardiologistswho examined patients and implanted pacemakers,at different mo-ments in the early history of the field. It highlights several episodesof substantialredefinition in which significant expansions of the listof medical indications for pacing occurred. It describes the field ofcardiac pacing at the end of the 1950s and 1960s and notes the orga-nizationalforces shaping the field in each decade, for physicianswhospecialized in pacing never made choices in a vacuum. The earlyexpansions of the meaning of cardiac pacing prepared the field forrapid growth once Medicarewas in place. One might expect that thecentrality of an artifact, the pacemaker,would endow pacing with aless 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 Amendmentsof 1976 (amendments, i.e., to the Food, Drug, and Cosmetic Act of 1938, which hadcreated 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 Arrhythmiato Infarction," Bulletin of the History of Medicine 58 (1984): 83-98, and "DiagnosticTechnologies: X-Rays, Electrocardiograms, and CAT Scans," Southern California LawReview 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 andtreating patients (clinical practice), as distinguished from laboratory research or theo-retical study.
  • Pacing the Heart 587signified by the mid-1970s bore little resemblance to the definitionsand assumptions of twenty years earlier. Pacing for EmergencyResuscitation, 1952 Although there had been some earlier experiments with pulsedelectrostimulationto resuscitatehuman beings from standstill of theheart, cardiac pacing as a set of systematicmedical procedures origi-nated in the 1950s.12Zoll, a cardiologist at Beth Israel Hospital inBoston, invented an external pacemaker and reported having usedit to revive a patient in 1952. Zollsapproach to pacing the heart wasimpressive for its simplicityand directness: the pacemakerconsistedof off-the-shelf components including a plug-in electrical stimulatorfamiliar to most doctors from their student days and simple needleelectrodes inserted beneath the skin of the patients chest on eitherside of the heart. (Zoll later substituted standard electrocardiographelectrodes that were strapped to the chest.) Electricalimpulses of twomilliseconds duration, fired through the chest with an amplitudeof 50-150 volts, would stimulate the ventricles to contract, therebyrestoring a circulationof blood to the brain and the body. Zollsfirstpublication 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," CardiologyClinics10 (1992): 561-71, argues that the basic scientific and technical knowledge requiredfor building simple pacemakers and pacing the heart for brief periods of time existedby the 1920s. However, chronic arrhythmias and "sudden cardiac death" (death within24 hours from a heart attack or cardiac arrest) had not yet been defined as critical andsolvable problems by physicians specializing in diseases of the heart. Working sepa-rately, physician-inventors in Australia and New York had actually invented pacingdevices in the mid-1920s and early 1930s, but their work received little attention andno support from the medical community. The situation had changed considerably bythe late 1940s as a result of many factors: improved understanding of arrhythmias,experience with open-chest defibrillation, rising physician confidence about workingaround and even within the exposed human heart, and the postwar redefinition ofthe hospital as a technological center for the delivery of acute-care medicine. 13Paul M. Zoll, "Resuscitation of the Heart in Ventricular Standstill by ExternalElectric Stimulation," New EnglandJournal of Medicine 247 (1952): 768-71. An electricalimpulse delivered to a single point in the myocardium (the muscular tissue of theheart) will be propagated from cell to cell. This depolarization results in mechanicalcontraction of the heart muscle. The energy required to instigate this process is quitesmall, on the order of 10-50 microjoules, if delivered directly to the excitable tissue.Zolls external pacing system required a high voltage because of the impedance associ-ated with the patients skin and subcutaneous tissues, the surface area of the electrodes,the short pulse duration, and other factors. In modified form, short-term externalpacing remains a widely used hospital technology.
  • 588 KirkJeffreyduring the 1950s.14 But this was not pacing as the public knows ittoday: Zolls invention carried with it a set of assumptions and prac-tices quite different from those now associated with implanted cardiacpacemakers. This first version of pacing meant emergencyresuscitationin the hospital from ventricular standstill. A pulse generator the sizeof a breadbox that plugged into the alternating current (AC) electricalsystem implied a bedridden patient. The high voltage required tocapture the heartbeat implied very short bouts of pacing-from min-utes to hours-and patients who were unconscious or sedated. Zollsfamous 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 upperchest that most patients found difficult to tolerate.5 Zoll invented his pacemaker to address an uncommon occurrenceknown as a Stokes-Adams attack, a potentially lethal complication ofcomplete heart block. In heart block, the hearts natural electricalsignal that triggers atrial and then ventricular contraction starts outin normal fashion from the sinus node, its source high in the rightatrium; when the impulse reaches the floor of the right atrium, con-duction cells within the heart muscle fail to propagate it on to theventricles, the major pumping chambers of the heart. One of severalsecondary "pacemakers" below the site of the block may then stimu-late the ventricles to contract; but these backup pacemakers fire moreslowly than the normal one, and because of the block the atrial andventricular 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 electronicsfirm outside Boston. Morris J. Nicholson et al., "A Cardiac Monitor-Pacemaker: Useduring 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. Birkuiet 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: ARenaissance," PACE 14 (1991): 1299-1316. 16Heart block is also known as atrioventricular or AV block. Cardiologists then andnow 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 reachthe ventricles while others do not. The text describes third-degree or complete block.See Johan Landegren and Gunnar Biorck, "The Clinical Assessment and Treatmentof Complete Heart Block and Adams-Stokes Attacks," Medicine 42 (1963): 171-96. Fora historical treatment of medical understanding of heart block, see David C. Schechteret 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 coronaryartery 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
  • Pacing the Heart 589 The person with heart block may not be able to tolerate physicalactivity and may show symptoms of congestive heart failure. Sooneror later, the person may also begin to experience brief episodes ofdizziness or unconsciousness from inadequate cerebral circulation.Eventuallythe circulationof blood may cease as the ventricles go intofibrillation(uncoordinated quivering) or come to a standstill.Loss ofconsciousness resulting from heart block was called a Stokes-Adamsattack,and mean life expectancyfrom the first such attackwas knownto be a matter of months because sooner or later an episode would Promptlyapplied, the Zoll pace-last long enough to kill the patient.17maker maintained a circulationthrough the few minutes of a Stokes-Adams attack that took the form of ventricular standstill.8Pacingthus 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, decidedthat cardiacpacing might solve a hitherto unknown complicationtheywere encountering. In adapting Zolls original idea to their needs,the surgeons invented a second variety of short-term pacing. The early open-heart operationswere often performed on childrenborn with congenital defects and known as "blue babies." By early1957, C. Walton Lilleheissurgical group at the Universityof Minne-sota had carried out 305 open-heart operations but had discoveredthat approximately one child out of ten developed complete heartblock as a consequence of the surgery. The surgeons concluded thatAcademyof Sciences 111 (1964): 835-47. The intense research on conduction diseasesthat got under way with the invention of cardiac pacing also demonstrated that withage, the specialized conduction fibers could gradually degenerate and lose the capacityto repolarize: Michael Davies and Alan Harris, "Pathological Basis of Primary HeartBlock," British Heart Journal 31 (1969): 219-26. 17 MArten Rosenqvist and Rolf Nordlander, "Survival in Patients with PermanentPacemakers," 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 broughtto 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 haverelied on Douglas P. Zipes, "Specific Arrhythmias: Diagnosis and Treatment," in HeartDisease, ed. Eugene Braunwald, 4th ed. (Philadelphia, 1992), pp. 667-725, esp. pp.710-15.
  • ! .I i,I .... . ,I .Ii .1~~~ a.1 - , I---_ -if I- !i! "--! .:i ........ . ...... .. ., -.-. .t r!!! I iU ...5 ! . I i . 1.j !!"-. i t(lr .!l ,~ - 1j. ?-?(t j .?I? ??? I ((( L 17~~~~~~~~~~~~~~~~~~~~~~~~~ It, .- Ii? t ft.. t (; --... * -r - - . X: .L.... ! _-, L , X _ i . 1 2 71 - - ,ftL. .-- -- . I-- P4I--iB_I FIG. 1.-Electrocardiogram of complete heart block showing complete dissociation of atrial acplexes). Elapsed time from one heavy vertical line to the next is 0.2 second. The P-P intervals indminute, while the intervals between QRS complexes indicate a ventricular rate of 35 beats per min ofMastering Dysrhythmias: Problem-SolvingGuide [Philadelphia, 1988], p. 238; reprinted courtesy A
  • Pacing the Heart 591they were occasionally disrupting the hearts conduction pathwayswhile repairing defects in the ventricular septum, the partition be-tween the right and left ventricles. The complication almost alwayskilled the patient.9 Short-termpacing seemed an obvious way to manage this problem;but with postsurgical heart block it would be necessary to pace achilds heart steadilyfor days or weeks to give the specializedconduc-tion cells of the heart time to heal. The Zoll pacemakerseemed moreappropriatefor brief and occasionalbouts of pacing. Certainly,youngchildren 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 (themyocardium)during open-heart surgery. They would bring the wireout through the surgical wound, bury a second wire under the pa-tients skin as an indifferent electrode, and connect both to a Zollpulse generator.20Days later, the surgeon could pull gently on thewire and dislodge it from the myocardium. By the fall of 1957, Lil-lehei was following this procedure whenever a patient showed signsof block during an open-heart operation.21 Since the myocardial pacing wire could capture control of theheartbeat at a voltage level at least one order of magnitude lowerthan external pacing,22 patient could remain painlesslydependent theon 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 ofMinnesota Medical School (St. Paul, Minn., 1989), pp. 516-19; Dwight C. McGoon etal., "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 abluish cast to their skin. 20All pacemakers consist of three elements: a pulse generator, electrodes (electricalconductors 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 oncardiac pacing, speaks of "the atrium" and "the ventricle" as if a human being hadonly one of each. In fact it is necessary to deliver a pacing impulse only to the chamberson one side of the heart since the cells of the myocardium will propagate it to theother. 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 AcutePostsurgical and Postinfarction Complete Heart Block," Annals of the New YorkAcademyof Sciences 111 (1964): 938-49; Wilson, pp. 516-19; Lillehei interview. 22Lilleheis surgical team reported capture at output voltages in the range of 1.5-4.5volts: Weirich et al., p. 362.
  • 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. Thetwo output terminalsprotrude from the top of the device. One of the knobs on thefront controls electricaloutput, the other the pacing rate. For a full description, seeC. WaltonLilleheiet al., "Transistor Pacemaker Treatmentof CompleteAtrioven- fortricular Dissociation," Journal of the AmericanMedical Association 172 (1960): 2006-10.(Photo courtesyof Medtronic,Inc.)plugged into the AC electrical system. The surgeons at Minnesotawished to get their child-patients out of bed and moving around;they worried that an electrical malfunction could send a patient intoventricular fibrillation (VF), a lethal arrhythmia. Lillehei thereforeasked an engineer who repaired electronic equipment at the medicalschool, Earl Bakken, if he could make a small battery-powered pulsegenerator. Delivered early in 1958, Bakkens new device was poweredby flashlight batteries and employed newly available componentscalled 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 experiencein pacing prepared the firm to grow along with the growth of cardiac
  • Pacing the Heart 593pacing. Medtronic soon became the worlds largest manufacturer ofpacemakers, a position it still holds today.23 Pacing in the 1950s: Treatment Acute Illness for Lilleheis myocardial approach to the heart emerged as an offshootof the revolution in heart surgery, but it still bore a strong resem-blance to Zolls original version of pacing. In both external and myo-cardial pacing, the patient was assumed to be gravely ill, confined tothe hospital, and pacemaker-dependent. Both systems ministered toacute crises, whether Stokes-Adams attacks or postsurgical heartblock. In both, the pacemaker was defined as a piece of hospitalequipment; its transformation into a more or less permanent additionto the patients own body was still a few years away.24 It might be asked why physicians chose cardiac electrostimulationto drive the heart rather than some entirely different technology-perhaps the administration of stimulating drugs such as atropine orisoproterenol. Researchers had experimented since the 1920s withdrugs that stimulated the heart; while these were often effective forbrief intervals in particular patients, it proved extremely difficult toadminister an appropriate amount of a drug at a steady rate, hourafter hour and day after day. More broadly, by the postwar yearsdoctors had grown accustomed to thinking of the heart as an electro-mechanical system, a "pump" activated by electrical impulses thatthe specialist could comprehend by analysis of the electrocardiogram(ECG).25 Investigators of the 1950s such as Zoll and Lillehei knew ofthe 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 goodfortune complete heart block happened to be the perfect "electricalfailure" to take up: it could be managed effectively in many cases bymeans of a device that was straightforward in concept. The pioneersin 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," SaturdayEvening 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 theElectrocardiogram (n. 9 above); Lynn Payer, Medicine and Culture (New York, 1988),pp. 74-75, 79-85.
  • 594 KirkJeffreyrelatively simple devices that did not require sensing as well as pacingfunctions or produce complex electrocardiograms. While attemptsto control heart block with drugs ran into repeated problems, thepacemakers of the late 1950s and early 1960s could quickly boast anumber of remarkable success stories. And doctors are much influ-enced by case histories.26 Physician-inventors and the electronic engineers who advised andworked 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 inthe late 1950s and early 1960s as part of a package that includedthoracic surgery and acute cardiac care.27 With its operating rooms,catheterization labs, and skilled nursing care, and with proceduressuch as electrocardiography, AC defibrillation, and cardiac catheter-ization, the large hospital had already emerged by the mid-1950s asthe appropriate locus for the practice of acute-care medicine relatingto the heart. Pacing was not only nurtured in the hospital, but itpromised to reinforce the hospitals role in the acute care of heartdisease.28 These institutional and technological developments took place in acultural climate that encouraged an activist, experimental approachin 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, "Changesin Medical Therapy during the Past Half Century," Medicine 59 (1980): 79-99. Lil-leheis group at Minnesota tried to manage seven cases of postsurgical heart blockwith epinephrine, aphedrine, atropine, and sodium lactate in 1954-55; they had nosurvivors. They then switched to isoproterenol (Isuprel) in 1955-57; out of nineteencases, 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 randomelectrical 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 theAmericanMedical 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); ofJoel 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, InSicknessand in Wealth:AmericanHospitals in the TwentiethCentury(New York, 1989), pp. 224-32; Jeffrey, "Invention and Reinvention" (n. 12 above).
  • Pacing the Heart 595lic supported medical research and looked forward to rapid successin the "war" against heart disease.29 David Sarnoff, chairman of theboard of the Radio Corporation of America and a noted technologicalsage, probably captured the enthusiasm of many in picturing a futuretime when "miniaturized electronic substitutes will be developed toserve as long-term replacements for organs that have become defec-tive through injury or age.... It is not too far-fetched to imagine aman leading a normal life with one or more vital organs replaced bythe refined substitutes of the future."30 In spite of such optimism, we should not overstate the centralityof 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 addedhundreds of new patients to the number who might be assisted bypacing, the total population with Stokes-Adams disease or postsurgi-cal block appeared small to most clinicians.31 The management ofelectrical 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 themarket for pacemakers in the late 1950s, pioneers in the field gavethem estimates on the order of five hundred units per year for theUnited States. Such figures were probably based on the assumptionthat 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); Presidents Commission on theHealth Needs of the Nation, Building AmericasHealth (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 moreremarkable than artificial teeth." Sarnoff had predicted in 1916 that the radio wouldbecome a "household utility." 311 have found no direct discussions of the incidence of heart block or Stokes-Adamsdisease from the period before 1960. Early investigators in cardiac pacing whom Ihave 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 becausecomplete heart block often terminated in death from cardiac arrest before a personcould see a physician. My impression is that the question of how many people hadheart block received little attention until after implantable pacemakers arrived on thescene. 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 ofheart block conducted during the period covered in this article is David B. Shaw andChristopher A. Kekwick, "Potential Candidates for Pacemakers," British Heart Journal40 (1978): 99-105. Shaw and Kekwick estimated the incidence of diagnosed cases ofheart block in their study area (Devon, England) at 97 per million population.
  • 596 KirkJeffreybattery powered, could serve the needs of dozens or hundreds ofpatients over a few years because the pacemakerwas a piece of hospi-tal equipment, not (yet) a part of the patientsown body. This misper-ception ensured that larger companies would leave the market tosmall specialty firms, such as Electrodyne and Medtronic, that hadalready developed relationshipswith medical research teams.32 An ImplantablePacemaker ChronicHeart Block for In the late 1950s, a second and more thoroughgoing redefinitionof 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 heartsown failed conduction system.33 This meant thatthe patient would receive electricalstimulationnot for a few days orweeks but for months and years-ideally, for the rest of a lifetime.Long-term pacing implied that the patient need not be confined to ahospital bed but might become fully ambulatory,leave the hospital,and lead the life of a semi-invalid.Rather than a brief and occasionalintervention, pacing would now become a permanent circumstancein the life of each patient. Although no pioneers in pacing had yetrecognized it, long-term pacing also meant that the pacemakerwouldrequire some kind of routine follow-up managementthrough an out-patient facility. This revised version of cardiac pacing did not emerge naturallyand directly from existing practicesbut instead required that doctorsradicallyreorganize their thinking. Indeed, some physiciansinvolvedwith pacing remained committed to the earlier concept of the pace-maker as an emergency or short-terminstrument.34 Certainlythe newversion of cardiac pacing entailed radical changes in the design ofpacing technology and in the activities surrounding its use. As an 32Telephone interview with Sam E. Stephenson, Jr., August 30, 1991. According toBakken, 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": interviewwith Earl E. Bakken, Fridley, Minnesota, May 23, 1990. 33This revised concept of pacing occurred to several research groups beginningaround 1955-56; I have not tried to award priority for the idea to any group inparticular. 34 Several of the researchers who at first failed to grasp the idea of long-term pacinghad earlier worked with defibrillation, perhaps the quintessential example of an acute-care technology; this experience dominated their perceptions of the pacemaker. Someviewed the pacemaker almost as if it were a kind of defibrillator. See the discussion atthe "Rockefeller Conference," September 1958, as excerpted in Kirk Jeffrey, ed., "TheConference on Artificial Pacemakers and Cardiac Prosthesis, 1958," PACE 16 (1993):1445-82. Joel D. Howell found an analogous pattern in early constructions of themeaning and utility of the ECG: Howell, "Early Perceptions of the Electrocardiogram"(n. 9 above).
  • Pacing the Heart 597unanticipated result, the new formulation also prepared the way fora vast increase in the manufacture and use of pacemakers. The idea for long-term pacing was "in the air"by about 1956, andresearchersdebatedits feasibilityat a one-dayconference in September1958. Zoll explained that resuscitatingpatientsfrom Stokes-Adamsat-tacksrepresentedno solutionto the underlyingproblemof heartblock;in a vivid presentation,he made the case for fundamentallyredefiningthe function of cardiac pacing: "Afterthe initial excitement of savingthe patient from the initialepisode of standstill,everybodyrelaxes andyou come back later ... and find the patient had another episode....You can resuscitatea patient... if you are ready all the time for therest of the patientslife, 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 incomplete heart block and suffering dozens of Stokes-Adamsattacksdaily. Rather than restartingthe heart time and again by means of anexternal pacemaker,Hunter opened the patientschest and sutured anexperimental 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 operatingtable,"Hunter later recalled. "Wejust kind of kept his heart going bypounding his chest."Engineer Norman Roth attachedthe lead to oneof the new battery-poweredexternal pulse generators. "A lot of otherpeople were in the room, and when it startedIjust couldntbelieve myeyes. Because its one thing [to have] a nice little compact heart in achild; but this was a 72-, 73-year-oldman with a big bulbous heart thatwas kind of like a big jellyfish in there, sort of semi-blue; and all of asudden it startedto pump, vigorouslyand accordingto the rate that wewanted, and we could control it, and all of a sudden he startsto wakeup! So we had to put him to sleep and finishthe operation. I dont knowwhat I said; someone said, My God, it worked!"36 Hunters 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 Zolls first fourteen pacing cases as reported in 1954, eight had died from laterStokes-Adams attacks after an initial successful resuscitation via the pacemaker. SeePaul 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 surgeonto turn off the external pulse generator to demonstrate its functioning for visitingcardiologists. Mauston would slip into unconsciousness within a few seconds, "then Idsnap it on again, and hed come right out of it. I did that several times. I had a lot of
  • 598 KirkJeffreylived in good health for nine more years, dependent on his pacemakerthe entire time. A reporter wrote that "although he occasionally fretsat being unable to go out on the golf course as he used to, he putts onthe living-room rug..., gets up and downstairs and walks around theneighborhood."37 This case, which had arisen as a clinical emergency rather than aspart of a research program, was one of several around 1959-60 todemonstrate that it was possible to pace the heart over an extendedperiod and send the patient home.38 By 1959 several research teamswere already experimenting with new kinds of pacemakers thatwould be more suitable for long-term use. Most of the new designscontemplated an implanted, battery-powered pulse generator to elim-inate a major source of infection, the pacing wire that came throughthe patients chest. A fully implanted device would also ensure thatthe doctor retained complete control of the pacemaker by putting itwhere the patient could not touch it. However, implanting the pulsegenerator 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 wereracing to come up with a practical long-term pacing device. Teamsin Stockholm and London implanted several pacemakers manufac-tured by the Swedish firm of Elema-Shonander between 1958 andearly 1960. The Elema pulse generator was rechargeable by an induc-tion coil placed on the patients body. This device had technical prob-lems, and in 1961 the company introduced a successor with mercurycells. Around the same time, a group at Yale University experimentedwith 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 Id turned off his pacemaker." 37Samuel W. Hunter et al., "A Bipolar Myocardial Electrode for Complete HeartBlock," Journal-Lancet 79 (1959): 506-8; David C. Schechter, "Background of ClinicalCardiac Electrostimulation. VII. Modern Era of Artificial Cardiac Pacemakers," NewYorkStateJournal of Medicine 72 (1972): 1176-81; Spencer (n. 23 above); interview withHunter. The electrode was an experimental model developed by Norman Roth, anengineer at Medtronic. 38Prior to Hunters case, the longest episode of pacing had probably involved apatient at Montefiore Hospital in the Bronx who had been intermittently pacemaker-dependent (and hospital-bound, though ambulatory) for ninety-six days in the fall of1958. See Seymour Furman and John B. Schwedel, "An Intracardiac Pacemaker forStokes-Adams Seizures," New England Journal of Medicine 261 (1959): 943-48. Thiscase is discussed below. 39A. H. M. Siddons and ONeal Humphries, "Complete Heart Block with Stokes-Adams Attacks Treated by Indwelling Pacemaker," Proceedings of the Royal Society ofMedicine 54 (1961): 237-38; Rune Elmqvist, "Review of Early Pacemaker Develop-
  • Pacing the Heart 599 In June 1960, at the Veterans Administration (V.A.) Hospital inBuffalo, New York, an elderly man received the first successful fullyimplanted pacemaker. Designed by electrical engineer WilsonGreatbatch, it was implanted by William Chardack, a surgeon.40 TheChardack-Greatbatch pacemaker, licensed to Medtronic and modi-fied in various ways, quickly set the standard for cardiac pacemakersin the United States. The first version to reach the market containedonly eight circuit components including two junction transistors. Thepulse generator, slightly larger than a pocket watch, encapsulated thecircuitry and a mercury-cell battery in silicone rubber. Devices of thisgeneration were known as asynchronous, fixed-rate pacemakers: theyhad no capacity to sense electrical activity within the heart and couldnot vary impulse rate or amplitude; they simply fired at a presetrate such as 70 impulses per minute.41 But the Chardack-Greatbatchpacemaker was a wonder for its time. After several early failures frombroken wires, Chardack designed a coiled-spring lead that provedremarkably reliable.42 (See fig. 3.) Inventing permanent cardiac pacing involved not only the device butthe 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 patients left abdomen asa site for the pulse generator. He then made a large chest incision andment," PACE 1 (1978): 535-36; William W. L. Glenn et al., "Remote Stimulation of theHeart by Radiofrequency Transmission," New England Journal of Medicine 261 (1959):948-51. The "main line" of development, as described in the text, was pursued inthe late 1950s by Zoll, William Chardack, and other teams, with Chardacks groupannouncing the first successful clinical case, an important symbolic milestone in theeyes 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 problemsthey 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 flexionsper year from the motion of the beating heart without breaking or causing a lesion inthe heart wall. Chardacks group did not learn of Ake Sennings work in Stockholmuntil 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 YorkAcademyofSciences 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, FrankHenefelt, is interviewed in Spencer (n. 23 above).
  • 600 KirkJeffrey FIG. 3.-The Medtronic5850, a Chardack-Greatbatch implantablepacemakerfromabout 1963, showing the coiled-spring lead and myocardialelectrodes invented byWilliamChardack. 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 patientsskin. Connectingwire A to B via a small incision increasedthe pacemakeroutput; connecting B to Cdisabled 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 fromthe pacemaker pocket to the heart, sutured the two electrodes to theventricular muscle, and plugged the lead into the pulse generator. Re-placing a depleted pulse generator was simpler: the surgeon made asmall 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. ofChest,ed. John H. Gibbon,Jr., et al., 2d ed. (Philadelphia,1969), pp. 824-65, givesdetails of surgical technique. By the mid-1960s it had become standard practice toemploy a temporarytransvenousendocardiallead (describedbelow) to maintaintheheart rate before and during surgery for implantationof a permanent myocardialpacemaker.Because of unexpectedlyrapid batterydepletion and occasionalwire fail-
  • Pacing the Heart 601 NoncompetitivePacing for IntermittentBlock Until about 1965, permanent pacing of the heart had the characterof an experimental technology, with journals often publishing ac-counts of unexpected crises such as broken wires and discussions ofpossible alternativesto mercuricoxide cells as the power source. Somepractitionersalso became concerned that asynchronouspacing mightinduce ventricularfibrillationin occasionalpatients who did not havefixed 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; theirritabilityof the heart muscle and hence the danger of VF appearedgreatest when the pacemakerfired into tissue damaged by an earlierheart attack.44 Aware of the growing concern about pacemaker-inducedVF, thebiomedical engineer Barouh Berkovits, at American Optical Com-pany, designed a sensing capability into the pacemaker so that itwould fire at a fixed rate, exactly as in an asynchronous pacer, butwould reset itself if it sensed the depolarization of the ventricles.45ures, some early patientshad to endure a dozen or more implantprocedures.Clearly,lead replacement entailed a much more severe procedure than replacement of thepulse generator. The patient who had received Sennings implanted pacemaker in1958, Arne Larsson,survivedwithout pacing for more than a year after the failure ofthe 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 5486-89; WilliamM. Chardacket al., "Pacingand VentricularFibrillation," Annalsof theNew York Academy Sciences (1969): 919-33. It had long been knownthat stimulat- of 167ing the ventriclesduring their "vulnerablephase"could induce fibrillation,but someleading figures in the pacing field remained skeptical about the possibilityof pace-maker-inducedVF because the pacemakerstimulus was so small and because directevidence was lacking. It was difficult to demonstrate conclusively that pacemaker-induced VF had killed some patients unless their heart rhythmshad been monitoredat 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 pacerwould not deliver another impulse until a preset interval,e.g., 850 milliseconds,hadelapsed. In early pacemakersof this sort, the intervalwas immutable,but beginningin the 1970s it could be programmedby the physician.The Berkovits pacing modewas later renamed "ventricular inhibited"because a sensed ventricularpulse inhibited
  • 602 KirkJeffreyAmerican Optical announced its new pacemaker (variously describedas a "ventricular inhibited" or a "demand" pacemaker) in 1965 andwithin a few years had licensed other manufacturers to produce theirown devices capable of pacing "on demand." By 1969, four-fifths ofnew pacemaker implants involved devices configured to avoid compe-tition. Noncompetitive pacing had rapidly and completely supersededthe 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 beganto follow patients on pacemakers over intervals of many months, itdawned on some that pacing had created a new cause of death, VFresulting from pacemaker competition. The effort to account forthese deaths led cardiologists to the insight that some cases of com-plete heart block were not fixed but could revert to intermittent blockwith some normally conducted beats.47 Cardiologists had describedthe problem of pacemaker competition in print, but it was the engi-neer, Berkovits, who conceived of a way to solve it. He then invitedphysicians comments on the idea and their collaboration in clinicaltrials. 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 contributedto the medical framing of intermittent heart block and of the non-competitive pacing mode.48 Partly in order to circumvent the Berkovits patent on ventricularthe pacer from firing. See George H. Myers and Victor Parsonnet, Engineering in theHeart and Blood Vessels(New York, 1969), pp. 34-49; and Bryan Parker, "PacemakerElectronics," in Seymour Furman and Doris J. W. Escher, Principles and TechniquesofCardiac 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 ventricularinhibited pacemaker in May 1967; a patent fight with American Optical ensued. Theacceptance of noncompetitive pacing by 1969 is reported in Victor Parsonnet, "TheStatus of Permanent Pacing of the Heart in the United States and Canada," Annalesde cardiologieet dangiologie 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 noncompetitivepacing. Only after noncompetitive pacing had come into widespread use did compara-tive mortality data provide firm corroborative evidence supporting the hypothesis thatpatients on asynchronous pacers died more frequently than those on noncompetitivepacers. Before noncompetitive pacing, it had been more of a suspicion. See the Berko-vits interview (n. 44 above).
  • Pacing the Heart 603inhibited pacing, the Cordis Corporation introduced a "ventriculartriggered" pacemaker. In this design, the device paced the ventricleat a fixed rate; but a sensed ventricularcontraction,instead of inhib-iting the pacemaker, triggered it to fire instantaneously and thenrecycle. 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 hearts natural signal. The two sys-tems, ventricular inhibited and triggered, were both widely usedduring the late 1960s, but Berkovitssinhibited mode eventually pre-vailed because it caused less drain on the pacemaker battery andbecause it seemed to emulate the "natural" escape mechanism of theheart in which certain cells below the site of the block, capable ofspontaneously 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 from1960 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 openingof the chest. Since most patients were elderly men and women suffer-ing from severe heart disease, hospital mortality rates in the earlyand 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 andinto the pumping chambers. In 1958, Seymour Furman, a first-yearsurgicalresident 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, on1973), pp. 123-27. On the hearts "latent pacemakers," see Zipes, "Specific Arrhyth-mias" (n. 18 above), pp. 685-86. Berkovits maintained that a biomedical engineershould always strive to "follow nature-if you can learn from it, youd 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 pacingand later of dual-chamber pacing. Ironically, more "physiological" pacemakers alsoproved 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," inPhysiology 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," PACE3 (1980): 207-19. 50Chardack, "Cardiac Pacemakers and Heart Block" (n. 43 above), p. 837, reportingon a study from 1967 that had reviewed many large series.
  • 604 KirkJeffrey FIG.4.-Pincus Shapiro at MontefioreHospital, fall 1958. The lower unit on thecart is an ElectrodynePM-65pacemaker-defibrillator; restingatop it is an Electrodynemonitor with a small oscilloscope.The pacing lead enters a vein at the inside of thepatientsleft elbow.This apparatusplugged into a wall socket;the physician,SeymourFurman,later substituteda car batteryand a converter.(Photocourtesyof Medtronic,Inc.)the venous system and the right atrium and into the right ventricleof the patients heart while observing its progress on a fluoroscope.Not knowing of the Medtronic portable pulse generator, Furman hadconnected the lead to an Electrodyne pulse generator that pluggedinto the AC electrical system (fig. 4). This apparatus paced Furmanssecond patient intermittently for ninety-six days and enabled the manto walk up and down the hospital corridor; eventually, pacing wasdiscontinued, and the patient was able to leave the hospital and go
  • Pacing the Heart 605home.51Over the next two years, Furmanand his coworkersreportedon dozens of additional cases of transvenous pacing.52 From the first, transvenous pacing could claim some significantadvantagesover 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 techniquealso reduced the risk of damage to the heart tissue because the pacingelectrode either floated free in the ventricle or barely touched theventricularwall. Yet the transvenous route did not gain widespread acceptance forlong-term pacing in the United States until the late 1960s. Furmansyouth and relative lack of renown may have been a factor initially;his removal from the scene for two years military duty definitelyslowed the development phase of transvenous pacing. There wereearly reports of intermittent failure to pace and of the cathetersperforating the vein. Some time elapsed before a standard techniqueemerged: those interested in transvenous pacing tried several veinsbefore settling on one just beneath the collarboneas the most suitablefor 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 likeLillehei and Chardack,the medical world had grown accustomed tothe 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 oftemporary 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, wasreported in Furman and Schwedel, "An Intracardiac Pacemaker" (n. 38 above). Seealso "Electrode in Heart Saves Mans Life," New YorkTimes (November 27, 1958), p.36. 52See, e.g., Seymour Furman et al., "The Use of an Intracardiac Pacemaker in theControl of Heart Block," Surgery 49 (1961): 98-108, and "Transvenous Pacing: ASeven-Year Review," AmericanHeart Journal 71 (1966): 408-16; and Victor Parsonnetand Alan D. Bernstein, "Transvenous Pacing: A Seminal Transition from the ResearchLaboratory," 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, "ChangingFace of Twentieth-Century American Cardiology" (n. 8 above); Donald Baim andRichard J. Bing, "Cardiac Catheterization," in Cardiology:The Evolution of the Scienceand the Art, ed. Richard J. Bing (Chur, 1992), pp. 1-28.
  • 606 KirkJeffreyaccustom surgeons to the techniques of catheterization.54 Reportsfrom Europe of successful long-term transvenous pacing and the in-troduction of a flexible transvenous lead in 1965 (a variant on Char-dacks coiled-spring design) contributed to a shift toward the transve-nous technique. Perhaps the clinching factor proved to be doctorsgrowing realization that the transvenous procedure was less risky fortheir elderly patients. Hospital mortality rates from transvenous pac-ing were 0-3 percent.55 Indeed, Chardack himself began to use thetransvenous route. By 1970, experienced implanters had switched inlarge numbers to transvenous pacing, while new entrants to the fieldwere accepting it as the normal path to the ventricle.56 Today virtuallyall pacing leads are introduced transvenously and stimulate the heartfrom 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 exemplifyingthe "desperation-reaction" model of technological diffusion: when adisease 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 ofthe 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, "IntravenousCardiac Pacemaking," Journal of the American Medical Association 184 (1963): 582-83;I. Richard Zucker et al., "Dipolar Electrode in Heart Block," Journal of the AmericanMedical Association 184 (1963): 549-52. 55 Rodney Bluestone et al., "Long-Term Endocardial Pacing for Heart-Block," Lancet2 (1965): 307-12; Hans Lagergren et al., "One Hundred Cases of Treatment forAdams-Stokes Syndrome with Permanent Intravenous Pacemaker," Journal of Thoracicand 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. Parsonnets pace-maker team at Newark Beth Israel Medical Center in Newark, New Jersey, had gonefrom six permanent transvenous pacemakers out of thirty-one implants in 1964 totwenty-four out of thirty in 1965. 57In the early 1970s, manufacturers introduced kits to assist the physician withtransvenous lead manipulation. The kit includes a stylus through which a temporaryguide wire and then the lead itself are introduced to the vein and advanced into theheart. The procedure can be more time-consuming if leads are to be introduced toboth 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 RejectingInnovations: Clinical Diffusion of Health Care Technology," in The Machine at the
  • Pacing the Heart 607was approaching twenty thousand per year in the United States, whileprimary 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 inthe 1960s that even speaking of the decade as a single era may appearto strain logic. Yet all the innovations were introduced in furtheranceof a clear, overriding goal: to create a prosthetic device that wouldpermanently manage a heart in complete block. To all appearances, both the pacemaker and the procedure forimplanting it had stabilized by 1970: the standard pacing device ofthat era was a fully implanted, ventricular inhibited pacemaker thatstimulated 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 andventricles, 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 thecentral 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 characterof American medicine. Throughout the 1960s, surgeons and devicemanufacturers were the principal sponsors of pacing development.Since the standard implantation technique of the early 1960s entailedexposure of the myocardial surface of the heart, pacing was dissemi-nated in tandem with heart surgery itself, proceeding generally fromcore institutions (large medical centers often affiliated with medicalschools) to the periphery (doctors in private practice with privilegesat general hospitals).60Bedside, ed. Stanley Joel Reiser and Michael Anbar (New York, 1984), pp. 65-92;Thomas P. Hughes, "The Development Phase of Technological Change," Technologyand Culture 17 (1976): 423-31. The implantable pacemaker appears to be a case inwhich innovation (the introduction of the technology into the marketplace and itsdiffusion into widespread use) proceeded simultaneously with development. This pat-tern would be highly unlikely in a new life-sustaining medical device today becausethe Food and Drug Administration, under the Medical Device Amendments of 1976and the Safe Medical Devices Act of 1990, would refuse to license the device forgeneral 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. 49above), pp. 41-48. 60Pacemaker manufacturers estimated in the early 1970s that between one-quarterand 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 PermanentPacing" (n. 46 above), p. 287; and Daniel M. Fox, Health Policies, Health Politics: TheBritish and AmericanExperience, 1911-1965 (Princeton, N.J., 1986), p. 210 and passim.
  • 608 KirkJeffrey Chardackof the V.A. Hospital in Buffalo was the pivotal medicalfigure in these years: Chardacksannouncement of the first clinicallyeffective implant in 1960, his invention of the coiled-springelectrodein 1962, and his meticulous analyses of his groups successes andfailures galvanized others to try cardiac pacing. Chardack and hisassociate,engineer WilsonGreatbatch,worked closely with the manu-facturing firm Medtronic in Minneapolis. For nearly a decade, allMedtronic pulse generators bore the "Chardack-Greatbatch" brandname. The team from Buffalo were "key consultants"to the firm,overseeing its implantablepacemakerprogram and keeping in touchwith clinicians around the United States.6 But Medtronic was by nomeans the only firm to introduce a "permanent"pacemaker in theearly 1960s. Sooner or later, each of the medical research teams thatwere 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 alsobecause of its preexisting reputation with medical equipment, its con-tacts with surgicalgroups, and its associationwith pioneers in cardiacpacing such as Lillehei, Bakken, Chardack,and Greatbatch.63 the Infast-developingpacing industry, the firm by mid-decade had assumedthe role of industry leader even though its first pacemakerdated backonly to 1958. For a number of reasons, the barriersto entry remained quite lowin the pacemaker industry throughout the 1960s. Federal require-ments for expensive and time-consumingcontrolled clinical trials toassess the safety and efficacy of life-sustaining medical devices didnot come into existence until 1976. Though manufacturerssecuredpatent protection for some devices and components, many of the keycomponents of early pacemakers such as batteries, wires, and thebiocompatible silicone-rubber encapsulation for a pulse generatorwere standard products purchased from other manufacturers;othercomponents, notablythe blocking-oscillator pacing circuitof the earlyimplantables,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 atMedtronic Library, Fridley, Minnesota; Jerry Flint, "Medtronic: Medicine, Electronicsand Profit," New YorkTimes(April 4, 1976), sec. 3, pp. 1, 9; Daniel R. Denison, CorporateCulture and OrganizationalEffectiveness (New York, 1990), pp. 95-108. The principallarge corporation to introduce a line of pacemakers was General Electric, but its devicesdid not win widespread acceptance; GE withdrew from pacing in 1977.
  • 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 18.21967 ......................... 8,250 15,000 18.81969 ......................... 16,000 27,000 19.51972 ......................... 25,000 45,000 19.91975 ......................... 57,000 90,000 22.71978 ......................... 69,000 100,000 24.11981 ......................... 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 CharExperience 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, eThomas J. Thomson (Philadelphia, 1965), pp. 213-49, at 246; Victor Parsonnet, "The Status of Permanent Pacand Canada," Annales de cardiologie et dangiologie 20 (1971): 287-91, at 288, and "A Survey of Cardiac Pacing iCardiacPacing: Proceedings of the IVth International Symposiumon Cardiac Pacing, ed. HilbertJ. T. Thalen (Assen, 1Victor 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 Abstractovarious years). = (col. 1 x 80%)/col. 3 *Approximately 80 percent of pacemaker patients are age 65 and older. Thus, col. 4
  • 610 KirkJeffreynological novelty. American Opticals "demand" and Cordiss "trig-gered" pacemakers were outstanding examples. The discovery and analysis of pacemaker competition and Berko-vitss invention of a pacing mode that could reliably sense and re-spond to cardiac activity pointed to emerging new relationshipsamong laboratory research, doctors clinical experience, and corpo-rate research and development. It was clear, first, that the growingclinical use of pacing had encouraged a great deal of new researchinto the precise nature of various heart conduction disorders thatproduced arrhythmias.64 As cardiologists gained new understandingof these disorders, advances in microcircuitry and other pacemakercomponents permitted manufacturers to introduce new pacingmodes suitable for managing them.65 During the decade of the 1960s,the locus of inventive activity shifted away from the laboratories ofphysician-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 bycreating a situation in which none of the three direct parties to themedical transaction-care provider, patient, and hospital-had apressing interest in economizing. As Rosemary Stevens remarks, 64Pacing engendered a great deal of interest in the physiology of the conductionsystem and the mechanisms of cardiac arrhythmias. For example, the number of arti-cles on the heart conduction system published in American medical journals and listedin Index Medicus rose tenfold between the years 1950-54 and 1963-67, from thirteento 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 ofHis-bundle electrocardiography, first reported in 1969, entailed atrial pacing. Invasivecardiologists employ catheter electrodes to record intracardiac electrical activity at vari-ous sites and may pace the atrium in the process; electrophysiologists overdrive theheart with a pacemaker to test its propensity to go into sustained tachycardia or VF. SeeBenjamin J. Scherlag et al., "Catheter Technique for Recording His Bundle Activity inMan," Circulation 39 (1969): 13-18; Scherlag, "The Development of the His BundleRecording 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 Cardiology28 (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, "TheDesign 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. 45above).
  • Pacing the Heart 611"hospital expenditures and reimbursement mechanisms drove eachother, in an expansionary spiral." By 1960, about two-thirds of theAmerican public enjoyed coverage under some type of private hospi-tal insurance; but the remaining third, including the elderly, lackedinsurance 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 federalprogram that would cover most costs of hospitalization and doctorsfees for Americans over age sixty-five. The 89th Congress passed theMedicare Bill, and President Lyndon Johnson signed it into law onJuly 30, 1965.67 Beginning on July 1 of the following year, the federalgovernment through the Medicare program began to pay costs associ-ated with pacemaker implantation and follow-up in patients agedsixty-five and older, or about four-fifths of the pacemaker patientpopulation.68 Medicare Part A (hospital insurance) paid for the pace-maker itself and for hospital services and procedures includingworkup and the primary or replacement implantation procedure.Medicare Part B covered 80 percent of physicians fees, outpatientfollow-up care, and subsequent office visits to check on the pacersperformance. By guaranteeing payment of "reasonable and customary" charges,Medicare greatly reduced the cost of cardiac pacing for the elderlypatient, provided no incentive for the hospital or the doctor to electnot to implant a pacer in marginal cases, and signaled that care pro-viders need not be greatly concerned about economizing in the choiceof 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," CardiovascularClinics8 (1977): 313. 69Starr, Social Transformation(n. 28 above), pp. 374-78, 383-88; Stevens, In Sicknessand in Wealth, pp. 281-83; Edward D. Berkowitz, AmericasWelfare Statefrom Rooseveltto Reagan (Baltimore, 1991), pp. 166-80. Martin Feldstein, The Rising Cost of HospitalCare (Washington, D.C., 1971), was one of many observers to point out that privatehealth insurance and Medicare contributed to increased demand for hospital servicesby effectively reducing the cost to the average elderly person.
  • 612 KirkJeffreyadvent of new implant techniques in fact substantially reduced thecost per patient between 1965 and 1975.70 But Medicare provided animmense 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. Onecan 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 ascardiologists once again expanded the list of indications for pacing.As late as 1968, almost all pacemakers had been implanted to managefixed 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 ofheart rhythm involving a default of the sinus node, the source of theelectrical impulses that trigger atrial and then ventricular contrac-tion-the hearts natural pacemaker. Within a few years, doctors wereimplanting nearly as many pacers for SSS as for heart block.72 Sick sinus syndrome had a diverse list of symptoms. Doctorslearned that the condition might manifest itself as persistent and no-ticeable slowdown of the firing rate of the sinus node, an inadequaterate response to increases in the persons 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. Inmore severe forms, the impulse might fail to spread beyond the sinusnode. 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 assumedthat 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 SinusSyndrome 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 ofindications. For background on the diagnosis, see Louis J. Acierno, The History ofCardiology (London and New York, 1994), pp. 353-54. On the medical and socialframing of disease, see Charles E. Rosenberg, "Framing Disease: Illness, Society, andHistory," in Framing Disease: Studies in Cultural History, ed. Charles E. Rosenberg andJanet Golden (New Brunswick, N.J., 1992), pp. xiii-xxvi.
  • Pacing theHeart 613might fibrillatetransientlyor continuously;the ventriclesmight adopta slow rate of contraction dissociated from the atria and eventuallycome to a halt. As long as episodes of SSS remained intermittent, the patient typi-cally experienced few or no symptoms. But as sinus failure grewmore severe, patients suffered dizziness, fatigue, transient blackouts,kidney failure, congestive heart failure, and pulmonary edema. Allof these resulted from the hearts inability to pump normally. Mostof the symptoms, however, were not unique to SSS and could varygreatly from one patient to another. The same patient could manifesta range of symptoms from one office visit to the next, and somepatients 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 inits early stages. Some of these abnormalitieshad been described decades earlier,but the sinus node had come in for renewed attention in the early1960s. The community of cardiac pacing specialistsbegan to pay at-tention to the syndrome at the end of the decade, after they hadresolved earlier uncertainties about pacing for heart block.74Theylearned that sinus node disorders, though often difficult to diagnose,were not rare. There also seemed general agreement in the early1970s that most such disorders did not present the same danger ofsudden 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)," AmericanHeartJournal 92 (1976): 539-40; William J. Scarpa, "The Sick Sinus Syndrome," Ameri-can HeartJournal 92 (1976): 648-60; Henri E. Kulbertus, "Experience with PermanentPacing 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 theInternational 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 presentimminent 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). Asnoted above, however, not everyone defined SSS as a single disease entity with a moreor less predictable course. Later research identified several sequelae that could be quiteserious: Kulbertus, p. 188.
  • 614 KirkJeffreycomplications of [SSS] are still unknown in great detail," it seemedprudent to "consider installing a pacemaker, for safetys sake, in thenear future." According to the leading expert on sinus node disease,the clinician "need not wait" for symptoms "to be intolerable"; assoon as "symptoms of any note" appeared, "a pacemaker had bestbe installed." Indeed, she added, "periodic or sustained SB [sinusbradycardia] can no longer go unchallenged, even if asymptomatic."76These statements opened the way for a rapid and substantial expan-sion of cardiac pacing by adding a large new class of arrhythmias tothose already managed on pacemakers and by redefining the pace-maker as a prophylactic device, insurance against possible (but unpre-dictable) future deterioration in a patients 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 primarypacemaker implantations in the United States were being carried outto manage the condition. This new indication for pacing coincidedwith a growth of about 125 percent in the number of new implantsbetween 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 HilbertJ. 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 (TheHague, 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 apacemaker." 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 byImplantation 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 withan 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 modesother than asynchronous and ventricular inhibited. Two years later, Parsonnet re-ported that fewer than half of the new pacemaker patients in the United States hadcomplete heart block, while more than half had presented with "sinus arrest" andother 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 informallyestimated 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 ofsinus node disease were the indications for 40.4 percent of new implants in the UnitedStates, while various forms of heart block accounted for 49.3 percent: B. S. Goldmanand Victor Parsonnet, "World Survey on Cardiac Pacing," PACE 2 (1979): W1-W17,at W7.
  • Pacing theHeart 615diffusion of pacing for sinus node disorders: the standard pacemakerof that era, the ventricular inhibited pacer, at first seemed well suitedfor SSS as well as heart block. Doctors could simply carry out moreprocedures of the sort they already knew how to do. However, just as concerns had developed about asynchronous pac-ing in the mid-1960s, questions soon began to arise about the suit-ability of ventricular inhibited pacing for sinus node disorders. Theventricular inhibited mode protected the patient from ventricularstandstill and from pacemaker-induced VF, but it by no means re-stored full cardiac function. The choice of this pacing mode impliedthat the physician was giving up on the patients sinus node andatria and would simply strive to maintain a ventricular beat.80 Butphysiological studies indicated that atrial contractions, when properlysynchronized with ventricular, augmented the hearts output of bloodby about 20 percent for people recovering from heart surgery or aheart attack. Properly synchronizing the beats of atria and ventriclesalso permitted the heart to respond more efficiently to heightenedbody activity level. Loss of normal synchrony could produce a varietyof negative effects.8 Sinus node dysfunction thus called for some form of atrial pacingto compensate for the failure of the sinus node. This implied a pace-maker with leads in both chambers. In 1971 such a device came onthe market, the AV sequential or "bifocal" pacemaker. Atrioventricu- 80Arthur B. Simon and Allan E. Zloto, "Symptomatic Sinus Node Disease: NaturalHistory after Permanent Ventricular Pacing," PACE 2 (1979): 305-14, at 306. Ferrer,Sick Sinus Syndrome(n. 73 above), p. 97, recommended "demand" pacing, i.e., ventricu-lar inhibited pacing. Parsonnet, "Survey of Cardiac Pacing," pp. 43, 45, showed thatin 1973 when over half of the primary implants were for conditions other than com-plete heart block, nearly nine-tenths of the pacemakers were ventricular inhibiteddevices. 81 Seymour Furman, "Therapeutic Uses of Atrial Pacing," AmericanHeart Journal 73(1973): 835-40; Sutton et al. (n. 49 above); Seymour Furman and Jay Gross, "Dual-Chamber Pacing and Pacemakers," CurrentProblemsin Cardiology 15 (1990): 117-79.The chief adverse effect of pacing with a standard ventricular inhibited pacemakerthat investigators had identified by the early 1970s was the "pacemaker syndrome" inwhich the ventricular pulse triggered by a pacemaker signal is conducted in a retro-grade direction back to the atria. As a result of retrograde conduction, a commonfeature of sinus node dysfunction, the atria contract against closed atrioventricularvalves; this forces blood backward from the atria into the pulmonary veins on the leftside of the heart and into the systemic veins on the right side. Symptoms can rangefrom lethargy and breathlessness to severe drop in blood pressure to syncope. AsKalman Ausubel and Furman noted, "The pacemaker syndrome represents a clinicalspectrum of intolerance to ventricular pacing": Kalman Ausubel and Seymour Fur-man, "The Pacemaker Syndrome," Annals of Internal Medicine 103 (1985): 420-29, at425; see also Sutton and Bourgeois (n. 5 above), pp. 126-31.
  • 616 KirkJeffreylar sequential pacing built on ventricularinhibited pacing: a sensing-pacing electrode was placed in the right ventricle as before, but theimplanting physicianalso introduced a pacing electrode into the rightatrium. The pacemakershifted automatically between three differentmodes as appropriate.In the presence of slow or absent atrialrhythmplus heart block, the pacemakercould deliver a stimulusto the atriumand then, after an appropriate interval, to the ventricle (true AVsequential pacing). If slow atrial rhythm was accompanied by ade-quate conduction from atria to ventricles, the pacemakercould pacethe atrium alone. In the presence of both adequate atrial rhythmand conduction from atria to ventricles, it would be inhibited fromstimulating at all. In effect, the pacemaker served as a prostheticconduction system.82 Despite the claim that AV sequentialpacing was more "physiologi-cal," the new pacing mode did not follow the same pattern of rapidphysician acceptance as had occurred with ventricularinhibited pac-ing in the mid- and late 1960s. For the next decade, doctors whoperformed pacemaker implants resisted all dual-chamber pacemak-ers, in part because introducing two transvenousleads was a difficultprocedure and positioning the atriallead so that it would consistentlypace the atrium sometimes proved time-consumingand frustrating.83The actual functioning of dual-chamberpacers was more difficult tocomprehend-the physician had to have a thorough understandingof pacemakertiming cycles-and the devices could produce complexECGs.84 The complexity of this device may, indeed, have exceededthe technologicaland electrophysiological comfort level of many doc-tors who were implanting pacemakersin the early 1970s. Since it was 82Jack M. Matloff et al., "Experience with Implanted Bifocal, Sequential DemandPacing," suppl. 3, Circulation42 (1970): 182 (abstract); Cesar A. Castillo et al., "BifocalDemand Pacing," Chest 59 (1971): 360-64. "Bifocal pacing" was the proprietary termadopted by American Optical Company for AV sequential pacing. The company soldunits at a variety of preset atrial and ventricular pacing rates and AV intervals. Todaythe dedicated AV sequential pacemaker is obsolete since successor dual-chamber de-vices can be programmed to sense and/or pace in either or both chambers. An earlierdual-chamber pacemaker, the Cordis Atricor, had held a small share of the market inthe 1960s. 83For skeptical discussions of AV sequential pacers, see Seymour Furman et al.,"Atrioventricular Sequential Pacing and Pacemakers," Chest 63 (1973): 783-89; Tha-len, "Cardiac Pacing in Sick Sinus Syndrome" (n. 76 above); Sutton et al., "PhysiologicalCardiac Pacing" (n. 49 above), p. 210. 84See, e.g., Sutton and Bourgeois (n. 5 above); Furman et al., A Practice of CardiacPacing (n. 7 above); Furman and Gross, "Dual-Chamber Pacing"; S. Serge Barold etal., "Characterization of Pacemaker Arrhythmias Due to Normally Functioning AVDemand (DVI) Pulse Generators," PACE 3 (1980): 712-23.
  • Pacing the Heart 617widely believed that SSS patients did not face a high immediate riskof sudden cardiac death (in contrast to patients in complete heartblock, who did face that risk), there apparently seemed little reasonto implant a dual-chamberpacemaker;doctors stuck with ventricularinhibited pacing for SSS.85Thus, in 1978-79, when about 40 percentof all implants ministered to sinus node dysfunction, 85 percent ofall newly implanted pacemakerswere ventricularinhibited, and onlyabout 6.5 percent were dual-chambereddevices.86 A Field for Cardiologists? As the pacemakerevolved from a tool in the doctorsintensive-carearmamentariumto a permanent prosthesis for chronic disease, manyof the roles and rituals of pacing-the elderly patient with ominoussymptoms, the ECGworkup, the implant procedure in a special roomfilled with high-tech equipment and masked professionals-super-ficiallycontinued to resemble those of acute-caremedicine. In effect,implantation of a pacemaker enabled the doctor to treat a chronicdegenerative disease such as heart block or sinus node disorder as ifit were an acute illness. If all went well, the patient walked out of thehospital "cured,"while the doctor received compensation for per-forming a procedure. But beneath the veneer of acute-caremedicine,pacing by the mid-1970s entailed complexities and physicianrespon-sibilitiesundreamed of just a few years earlier. It was already clear by the 1970s that "almostany physician withreasonable dexterity can learn to implant a pacemaker";but to earnrecognition as a fully competent specialist, the physician also had tobe conversant with the rapidly growing body of knowledge aboutarrhythmias,the ever-changing hardwareof pacing, pacemaker pro-gramming, the management of postimplant complications, and pa-tient follow-up over the long term. Surgeons or mixed teams of sur-geons and cardiologistscontinued to implant most pacemakers;but 85Barouh Berkovits, the designer of the AV sequential inhibited pacemaker, com-mented later that "benefits of sequential pacing are less dramatic" than the benefits ofventricular inhibited pacing for complete heart block, where "there is a life and deathissue to be considered": Barouh Berkovits, "A Modern Pioneers Perspective" (inter-view), Medtronic News 9 (1979): 9-11, at 10. However, later research indicated thatventricular inhibited pacing for SSS does not significantly reduce patient mortalitywhile dual-chamber pacing does make a considerable difference. See Raviele andDi Pede (n. 74 above), p. 284, citing many studies. 86Goldman and Parsonnet (n. 79 above), pp. W7, W9. Only 2 percent of the pacersimplanted were AV synchronous, while 4.5 percent paced in other modes capable ofstimulating the atrium. This survey probably has sampling problems, as the authorsconcede; but there seems no reason to doubt that the great majority of patients diag-nosed with SSS were receiving ventricular inhibited pacemakers in the late 1970s.
  • 618 KirkJeffreythe medical transactionincluded many new activitiesboth before andafter implant, and here the training of the cardiologist came intoplay.87 Because of the accumulationof knowledgeabout arrhythmiasof theheart, the clinicianof the 1970s had availablea wide range of possiblediagnoses.Varioussubcategoriesof heartblockhad been defined, eachpresentingsubtlydifferent manifestationsin the ECGand each invitingsomewhat different treatment by means of pacemakers.Disorders ofthe sinus node could be equallycomplex. A growing number of papersin the field focused on the analysisof difficultECGs.Withthe advent ofnew techniquesfor recordingelectricalactivityat sites within the heartitself, the physicianwas presented with even more tracingsto analyze.It wascardiologists,not surgeons,who possessedthe trainingand expe-rience for this kind of work.88 The hardware of cardiac pacing was also changing in ways thattended to recast pacing as a close relative of cardiology. The newerpacemakers presented the doctor with a vast array of decisions: themarketoffered dozens of models by the mid-1970s, many of them pro-grammable from outside the patientsbody by means of devices thatcommunicatedwiththe implantedpulse generatorthrough coded elec-tromagnetic pulses. The doctor could noninvasivelyand repeatedlychange pacing rate, pulse duration and amplitude, sensitivityof theelectrodes to spontaneouselectricalactivitywithinthe heart, and otherparameters.Millionsof different combinationswere theoreticallyavail-able, although most were inappropriatefor practicaluse.89 After 1970, the rising number of patients, increased pacemaker(and patient) longevity, and the growing complexity of pacemakersled many hospitals to open outpatient pacemaker clinics that main-tained contact with paced patients in the months and years after im-plant. By taking regular ECGs, techniciansunder physician supervi-sion could decide how to reprogram the pacer as the patientsdisease 87The quoted phrase appears in Parsonnet, "Cardiac Pacing as a Subspecialty" (n. 7above), p. 991. See also J. Warren Harthorne et al., "Who Should Implant a PacemakerSystem, Surgeon or Cardiologist?" in Thalen and Harthorne, eds. (n. 76 above), pp.263-70. 88Samuel Bellet, Clinical Disordersof the Heart Beat, 3d ed. (Philadelphia, 1971), is arepresentative text of that period. On His-bundle recording, see Scherlag et al. (n. 64above). 89David C. McGregor et al., "The Utility of the Programmable Pacemaker," PACE 1 (1978): 254-59. To the chagrin of leading figures in the field of pacing, as late asthe mid-1980s a substantial proportion of programmable pacemakers, perhaps two-fifths, were implanted with their default settings and never reprogrammed: VictorParsonnet et al., "Cardiac Pacing Practices in the United States in 1985," AmericanJournal of Cardiology62 (1988): 71-77, at 73.
  • Pacing the Heart 619progressed, judge when battery depletion called for replacement ofthe pulse generator, and spot other problems such as failure of thelead. For patients not able to visit the clinic, it was possible to transmita simple ECG indicating the pacemaker impulse rate by telephone;this was enough to forewarn of battery failure. By the mid-1970s,most physicians who were "frequent implanters" at large medical cen-ters had established pacemaker clinics located in or near their hospi-tals. For doctors who lacked any connection to a hospital-based pace-maker follow-up clinic, several private companies cropped up in theearly 1970s to handle pacemaker monitoring and record keeping.90 Transvenous pacing, the growing complexity of ECGs and pacingequipment, the longer survival of patients, and the obvious need forlong-term follow-up all contributed to a gradual de facto redefinitionof pacing as a distinct field but one with strong affinities to cardiology.Surgeons did not bow out overnight and continue to implant manypacemakers; but board certification in surgery no longer seemed, initself, an appropriate credential for a practice of cardiac pacing. By the1980s half of the implanters in the United States, and a higher propor-tion of newer entrants to the field of pacing, were cardiologists.9 Like the field of cardiac pacing, cardiology "took off" as a subspe-cialty after about 1970. It had required twenty-eight years (from 1942through 1969) for the American Board of Internal Medicine to certifythe first one thousand cardiologists. The next thousand took only fiveyears, and after 1975 more than one thousand physicians gained certi-fication eachyear. Many of the younger cardiologists moved into inva-sive cardiology, an informal hospital-based subfield centered on ad- 90In the mid-1970s, about one-half to three-fifths of pacemaker patients survivedfor at least five years after implantation: Furman, "Controversies" (n. 68 above), pp.313-14. On follow-up, see Furman et al., "The Pacemaker Follow-Up Clinic," Progressin CardiovascularDiseases 14 (1972): 515-30; Seymour Furman, "Transtelephone Ob-servation of Implanted Cardiac Pacemakers," Medical Instrumentation7 (1973): 196-202; Michael Bilitch et al., "Physician Follow-Up of Patients with Permanent CardiacPacemakers," in Thalen, ed., Cardiac Pacing (n. 49 above), pp. 443-48; and VictorParsonnet and George H. Myers, "Organization of a Cardiac Pacing Service," in CardiacPacing: A Concise Guide to Clinical Practice, ed. Philip Varriale and Emil A. Naclerio(Philadelphia, 1979), pp. 13-27. As of 1973, about half of the pacemaker centers inthe United States were estimated to have created some sort of organized pacemakersurveillance system: Parsonnet and Manhardt (n. 3 above), p. 254. 91Victor Parsonnet, "Pacing in Perspective: Concepts and Controversies," Circulation73 (1986): 1087-93, at 1092, and "Cardiac Pacing as a Subspecialty" (n. 7 above).Since 1983, the payment reforms imposed by Medicare have tended to advantagecardiologists over surgeons as implanters of pacemakers: Stamato et al., "PermanentPacemaker Implantation" (n. 4 above); T. Bruce Ferguson,Jr., et al., "Should SurgeonsStill Be Implanting Pacemakers?" Annals of ThoracicSurgery 57 (1994): 588-97.
  • 620 KirkJeffreyvanced technologies and such procedures as balloon angioplasty andcardiac pacing and more recently on new procedures such as ablationtherapy and coronary atherectomy. These invasive procedures employthe cardiologists traditional procedure, catheterization.92 The subspecialty of cardiology and the field of cardiac pacing fed oneach other. Through their technical studies of arrhythmias and theirpioneering use of heart catheterization, cardiologists had helped laythe groundwork for the framing of new diseases of the hearts electricalsystem and for pacings redefinition as a technology for long-term man-agement of chronic diseases. On their own turf, the analysis and man-agement of heart arrhythmias, they tended to manifest great optimismabout the benefits of pacing. They were highly receptive to the idea oftreating slowdowns of the heartbeat such as complete fixed heart block,intermittent heart block, and the sick sinus syndrome by giving the pa-tient an implanted pacemaker; and once pacing had gained acceptancein treating one type of arrhythmia, they were strongly inclined to ex-plore its utility in other situations.93 92 the redefinitionsof On cardiologyin recent decadesand the fieldsassociationwithinvasive technologies, see Howell, "ChangingFace of Twentieth-CenturyAmericanCardiology" 8 above);Braunwald(n. 29 above);Parsonnetand Bernstein,"Transve- (n.nous Pacing"(n. 52 above);and RichardS. Stack,Editorial:"NewInterventionalTech-nologies in Cardiology," 64 MayoClinicProceedings (1989): 867-70. 93Forfurther discussionof this pattern, see H. David Banta et al., Toward Rational inTechnology Medicine (New York, 1981), pp. 53-55, 58-72, 77-80; McKinlay(n. 2above); Ichiro Kawachi and Nicholas Wilson, "The Evolution of AntihypertensiveTherapy,"SocialScience Medicine (1990): 1239-43. Not surprisingly,the Ameri- and 31can practice of paying physicians for performing procedures has encouraged thegrowth of specialties such as invasive cardiology that are centered on procedures.Howell, "Diagnostic Technologies" (n. 9 above), shows that "regular" American physi-cians were able to raise their own professional status and differentiate themselves fromsectarians in the early 20th century by associating themselves firmly with science andtechnology. In contrast, cardiologists were sometimes cool to new pacing hardware thatwould entail drastic changes in their management of patients. They rapidly acceptedventricular inhibited pacing, transtelephone monitoring, and the lithium battery, butwere more cautious about dual-chamber and multiprogrammable pacemakers. In suchcases one senses very strongly the latent tension between the "leaders" in cardiac pac-ing, who perform many implants and speak up for new technology, and the thousandsof more technologically conservative physicians who perform only a few implants peryear. Useful discussions of the diffusion of new medical technologies that intenselydiscuss the role of physicians include Banta (n. 58 above); Eugene D. Robin, Mattersof Life and Death: Risks vs. Benefitsof Medical Care (New York, 1984); Joseph D. Bronzinoet al., Medical Technologyand Society:An Interdisciplinary Perspective(Cambridge, Mass.,1990); and Stuart S. Blume, Insight and Industry:On the Dynamicsof TechnologicalChangein Medicine (Cambridge, Mass., 1992), esp. pp. 5-21. Most scholars working on thesubject have been influenced by Stanley Joel Reiser, Medicine and the Reign of Technology(Cambridge and New York, 1978).
  • Pacing theHeart 621 Conclusion From its beginnings after World War II through the mid-1970s,the cardiac pacemaker might have served as an emblem of the clinicalsuccesses and the rapid redefinitions of postwar American medicine.In pacing, as in medicine generally, unmanaged growth stood out asa particularly striking characteristic. In the absence of a national reg-istry, authoritative statistical data on pacemaker implantations for theera before 1975 do not exist; but scattered information permits anestimate of the burgeoning number of procedures. It appears thatfrom the very early 1960s through the mid-1970s, the number ofimplants (counting primary and replacement procedures) doubledevery two to three years. Growth probably slowed for a few years inthe late 1970s because the number of replacements declined as alonger-lived kind of pulse generator, powered by lithium batteries,came into use. After about 1978, the rate of growth in pacing pickedup again and remained robust until Medicare payment reforms wentinto effect in 1983. Federal support for the consumption of health-care products and services by the elderly, advances in doctors ownpacing know-how based on an accumulation of clinical cases, andongoing research into heart arrhythmias encouraged in part by thesuccess of pacing itself all contributed to this growth in pacing be-tween 1952 and 1975. Like heart surgery and cardiology, pacing was optimally positionedto flourish in an era of optimism about medical technology as themeans to "conquer" refractory diseases. Federal reimbursement andregulatory policies played a powerful enabling role in the expansionof pacing: until 1976, the Food and Drug Administration lacked au-thority to regulate the introduction of new medical devices, and Medi-care imposed no serious oversight on reimbursement for pacemakerimplantations before 1983.94 Lest the point be overlooked, we should also note that pacing was 94Stevens, In Sicknessand in Wealth(n. 28 above), pp. 322-27. Before 1983, Medicarepaid doctors and hospitals the "usual and customary" charge for a given procedure.Under this system, incentives to economize were weak. In 1983, amendments to theSocial Security Act changed Medicare to a prospective reimbursement system. Phasedin over the next three years, the new rules grouped all hospital treatments into 467Diagnosis-Related Groups (DRGs), each of which was assigned a fixed rate of reim-bursement regardless of the length of the patients stay in the hospital or the resourcesused. The DRG system established a price ceiling for each reimbursable procedureand thereby pressured hospitals to economize. If the hospital could treat the patientfor less than the fixed amount, it came out ahead. In 1985, the DRG system wasextended to physician services. Of the original 467 DRGs, four involved pacemaking,two covering initial implants and two covering replacement or revision of a pacemaker.
  • 622 KirkJeffreyclinically effective: it kept patients alive in complete heart block whoseprognosis without pacing would have been extremely poor, and be-ginning in the mid-1960s it enabled many of them to enjoy moder-ately active lives. To this extent, Zoll is correct: "It really worked."But technological triumphalism seems out of touch with the needs ofthe 1990s. Even while conceding that cardiac pacing has saved thou-sands of men and women from sudden cardiac death or from a poorquality of life in old age, that the pacemaker is a wonder of engi-neering, and that the per-patient cost of pacing is modest comparedto some other medical procedures, observers have still been troubledby the growth dynamic of the field.95 As concern built up in the 1970s and 1980s about the high cost ofhealth care in the United States, many critics singled out advanced med-ical technologies as a principal cause of the financial crisis in Americanhealth care. Cardiac pacing came under direct attack in 1982 when thePublic Citizen Health Research Group, an organization under theRalph Nader umbrella, announced that over one-third of the perma-nent pacemaker implantations performed in Maryland hospitals in1979 and 1980 had been "unnecessary" or "questionable."96 A blue-ribbon committee appointed by the Maryland Society of Cardiology re-viewed the medical records of pacemaker patients but concluded thatonly a few of the implants had truly been "unnecessary."97 The controversy-one of several that erupted over cardiac pacingin the early 1980s-suggested that more than twenty years into thehistory of pacing for chronic bradycardia, high-tech medicine was aslikely to evoke uneasiness as celebration; perhaps the controversy alsoindicated that the heroic image of the heart specialist had eroded.The Nader group, however, had an incomplete understanding of thedynamics of growth in cardiac pacing. It was certainly true that thepractice of paying doctors for performing procedures gave them fi- 95Interview with Paul M. Zoll, Boston, February 5, 1990; Rosenqvist and Nordlander(n. 17 above). Electrostimulation of the heart, however, has probably played a rathersmall part in the overall decline in mortality rates from heart disease; see Lee Goldmanand E. Francis Cook, "The Decline in Ischemic Heart Disease Mortality Rates," Annalsof Internal Medicine 101 (1984): 825-36. For statements by troubled physicians, seeVictor Parsonnet, "The Proliferation of Cardiac Pacing: Medical, Technical, and Socio-economic Dilemmas," Circulation65 (1982): 841-45; John A. Kastor, "Pacemaker Ma-nia," New England Journal of Medicine 318 (1988): 182-83. For comparative implantrates by country in the 1970s, see Goldman and Parsonnet (n. 79 above), pp. W3-W4. 96Health Research Group, PermanentPacemakersin Maryland (Washington, D.C., July1982). 97Leonard Scherlis and Donald H. Dembo, "Problems in Health Data Analysis: TheMaryland Permanent Pacemaker Experience in 1979 and 1980," AmericanJournal ofCardiology51 (1983): 131-36.
  • Pacing the Heart 623nancial incentives to go ahead with implants in borderline cases. Yetto claim that many implants were obviously "unnecessary" was to missan important point. Observers outside the field took it for grantedthat some stable, authoritative set of implantation criteria must exist,but the medical definition of necessity had never remained fixed forlong.98 The field had changed repeatedly, and with each change phy-sicians list of indications for pacing had grown longer. This expan-sionist tendency had been visible even before the creation of theMedicare program in the mid-1960s. By 1972, many patients werereceiving pacemakers for arrhythmias that were not immediately lifethreatening yet seriously compromised their capacity to live evenmoderately active lives. In that sense, perhaps one could say that theimplants were "unnecessary." But one could claim equally well that aredefinition of "necessity," indeed of what good health means for anelderly person, was under way in American society, prompted in partby the success of cardiac pacing and other treatments of chronic de-generative conditions of old age. In medicine as in other social realms, the purely technical proper-ties of a new device or procedure do not determine how the innova-tion will be deployed. The hardware of pacing and the standard tech-niques of applying the pacemaker changed fundamentally between 1952 and 1975. But even more significantly, the customs and habitsof doctors changed. In the early years, doctors generally understood pacing as an emergency or short-term treatment applied in the hospi-tal to patients in acute distress. Later they reconceived pacing as away to manage chronic heart block "permanently." Still later theydefined new diseases of the heart that were suitable for pacing; they also redefined their practice to include active management of the pacemaker long after the day of implantation. In the process, physi-cians and hospitals created entire new organizations called pacemaker follow-up clinics that were staffed by technicians and maintained elab- orate computer databases on hundreds, perhaps thousands, of pa- 98Formal criteria for implantation were introduced in 1984 but have been revisedand expanded: Robert L. Frye et al., "Guidelines for Permanent Cardiac PacemakerImplantation," Journal of the American College of Cardiology4 (1984): 434-42, a reportof a joint task force of the American College of Cardiology and the American HeartAssociation. Compare Joel D. Howells observation that the practice of cardiology-indeed the very meaning of the term cardiology-has undergone repeated redefini-tion. "The structure and content of cardiology" do not enjoy a stable reality separatefrom the goals of physicians, the struggle of organizations, and broader developmentsin medical thought. Cardiology "is historically mediated and constantly changing"(Howell, "Changing Face of Twentieth-Century American Cardiology" [n. 8 above],p. 780).
  • 624 KirkJeffreytients. All this would have been unimaginable in 1952 or even 1965.Doctors who were reluctant to go along with this new role as activemanagers of patients hearts would eventually get out of the field,leaving it in the hands of those who were more comfortable with therepeated reinvention of cardiac pacing.