Ventricular Tachycardia: Historical Perspective BRIAN McGOVERN, MARK H. SCHOENFELD, JEREMY N. RUSKIN, HASAN GARAN, and PETER M. YURCHAK From the Cardiac Arrhythmia Service, Massachusetts General and Spauiding Rehabilitation Hospitals, Boston, Massachusetts McGOVERN, B., ET AL.: Ventricular tachycardia: Historical perspective. Ventricular tachycardia is now diagnosed frequently in patients with organic heart disease. Although ventricular tachycardia was first demonstrated electrocardiographically 75 years ago, the natural history, fundamental mechanisms, and optimal management have remained elusive. Early observers commented on the rarity of occurrence and poor prognosis associated with this arrhythmia, yet with time, some patients with ventricuiar tachycardia were reported to survive for prolonged periods. Because of the sporadic nature of the arrhythmia and its variable prognosis, assessment of the efficacy of therapies has been difficult. A wide variety of treatments has been advocated with enthusiasm, but only a few have been consistently reported to be effective. Citation of historical data to claim benefit from new treatments should be viewed with caution. (PACE. Voi. 9, May- June, 1986) ventricular tachycardia, arrhythmias, history The invention of a new instrument or new melhod of investigation determined the lines along which knowledge was to ad- vance. Seventy-five years have passed since the first electrocardiographic demonstration of ventricular tachycardia which was considered an uncommon finding for many years, but the introduction of bedside and ambulatory electrocardiographic monitoring within the past 30 years has allowed the frequent diagnosis of this arrhythmia. Ven- tricular tachycardia is now recognized as a rela- tively common arrhythmia during acute myocar- dial infarction, in patients with chronic myocardial diseases, and as a precursor of ventricular fibril- lation in victims of sudden cardiac death. In this paper, we describe the evolution of knowledge concerning ventricular tachycardia and seek to assess the relevance of earlier observations to our present understanding of the arrhythmia. Address for reprints; Brian McGovern. MB. Cardiac Unit, Mas- sachuselts Genera! Hospital, Boston. MA 02114 USA. This study was supported in part by Grant ROl-HL25g92 from Ihe Heart, Lung and Blood institute and the National Institutes of Health. Bethesda, Maryland. Drs. Ruskin and Garan are the recipients of American Heart Association Established Investi- gatorships 81-177 and 84-209, respectively. Received December 4, 1985; accepted December 18. 1985. Early Clinical Observations (1909-1922) The first electrocardiograpbic description of ventricular tachycardia is attributed to Thomas Lewis. In 1909, he described a patient with short- ness of breath, precordial pain, and dropsy in whom he observed from three to eleven "succes- sive extrasystoles"^ (Fig. 1). He deduced from the electrocardiogram, venous pulse recording, and clinical evidence tbat the rhythm was of ventric- ular origin. Tbe idea tbat paroxysmal tachycardia could originate from tbe ventricle bad been sug- gested previously and independently by Macken- zie and Wenckebacb on tbe basis of phlebogram tracings.^"* Furthermore, three years earlier in 1906, Einthoven had recorded ventricular pre- mature beats and ventricular bigeminy using bis string galvanometer.^ Lewis' observations were followed by a series of case reports in which pa- tients with paroxysmal wide-complex tachycar- dias were described."*"" The ventricular origin of these arrhythmias was assumed because the ven- tricular rate exceeded the atrial rate, or at times simply because tbe QRS complex was wide. Rob- PACE. Vol. 9 May-June 1986 449
Transcript
Ventricular Tachycardia:Historical Perspective
BRIAN McGOVERN, MARK H. SCHOENFELD, JEREMY N. RUSKIN,HASAN GARAN, and PETER M. YURCHAK
From the Cardiac Arrhythmia Service, Massachusetts General and SpauidingRehabilitation Hospitals, Boston, Massachusetts
McGOVERN, B., ET AL.: Ventricular tachycardia: Historical perspective. Ventricular tachycardia is nowdiagnosed frequently in patients with organic heart disease. Although ventricular tachycardia was firstdemonstrated electrocardiographically 75 years ago, the natural history, fundamental mechanisms, andoptimal management have remained elusive. Early observers commented on the rarity of occurrence andpoor prognosis associated with this arrhythmia, yet with time, some patients with ventricuiar tachycardiawere reported to survive for prolonged periods. Because of the sporadic nature of the arrhythmia and itsvariable prognosis, assessment of the efficacy of therapies has been difficult. A wide variety of treatmentshas been advocated with enthusiasm, but only a few have been consistently reported to be effective. Citationof historical data to claim benefit from new treatments should be viewed with caution. (PACE. Voi. 9, May-June, 1986)
ventricular tachycardia, arrhythmias, history
The invention of a new instrument or newmelhod of investigation determined thelines along which knowledge was to ad-
vance.
Seventy-five years have passed since the firstelectrocardiographic demonstration of ventriculartachycardia which was considered an uncommonfinding for many years, but the introduction ofbedside and ambulatory electrocardiographicmonitoring within the past 30 years has allowedthe frequent diagnosis of this arrhythmia. Ven-tricular tachycardia is now recognized as a rela-tively common arrhythmia during acute myocar-dial infarction, in patients with chronic myocardialdiseases, and as a precursor of ventricular fibril-lation in victims of sudden cardiac death. In thispaper, we describe the evolution of knowledgeconcerning ventricular tachycardia and seek toassess the relevance of earlier observations to ourpresent understanding of the arrhythmia.
Address for reprints; Brian McGovern. MB. Cardiac Unit, Mas-sachuselts Genera! Hospital, Boston. MA 02114 USA.
This study was supported in part by Grant ROl-HL25g92 fromIhe Heart, Lung and Blood institute and the National Institutesof Health. Bethesda, Maryland. Drs. Ruskin and Garan are therecipients of American Heart Association Established Investi-gatorships 81-177 and 84-209, respectively.
Received December 4, 1985; accepted December 18. 1985.
Early Clinical Observations(1909-1922)
The first electrocardiograpbic description ofventricular tachycardia is attributed to ThomasLewis. In 1909, he described a patient with short-ness of breath, precordial pain, and dropsy inwhom he observed from three to eleven "succes-sive extrasystoles"^ (Fig. 1). He deduced from theelectrocardiogram, venous pulse recording, andclinical evidence tbat the rhythm was of ventric-ular origin. Tbe idea tbat paroxysmal tachycardiacould originate from tbe ventricle bad been sug-gested previously and independently by Macken-zie and Wenckebacb on tbe basis of phlebogramtracings.^"* Furthermore, three years earlier in1906, Einthoven had recorded ventricular pre-mature beats and ventricular bigeminy using bisstring galvanometer.^ Lewis' observations werefollowed by a series of case reports in which pa-tients with paroxysmal wide-complex tachycar-dias were described."*"" The ventricular origin ofthese arrhythmias was assumed because the ven-tricular rate exceeded the atrial rate, or at timessimply because tbe QRS complex was wide. Rob-
PACE. Vol. 9 May-June 1986 449
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Figure 1. Thispgure is reproduced from Lewis.^ U is read /ram right Io left. The top tracing showsthe electrocardiogram and the lower tracing a ph]ebograni. Leivis lermed alrial and ventricularactivalion the "a" and 'V" waves, respectively. There are three consecutive venfricu/nr extrasystolesdemonstrated. Time lines art; shown above the tracing (Lettering retouched for clarity). Reproducedwith permission from the LancetJ.
inson and Herrmann suggested that coronary oc-clusion was a frequent cause of ventricular tachy-cardia and the prognosis in these cases appearedto be poor.^ Meanwhile, in France. Gallavardin wasstudying electrocardiograms in patients with ad-vanced heart disease and observed that terminalventricular tachycardia was preceded by runs ofrapid ventricular tachycardia in some patients.'"It had been recognized previously that ventricularfibrillation was the most common terminal elec-trocardiographic finding in dying patients." butGallavardin's observations clearly suggested thatruns of ventricular tachycardia, particularly whenrapid and polymorphic, might herald the onset ofventricular fibrillation. Of particular interest alsoin the early French literature is tbe recognition ofcases of "benign" ventricular tachycardia in whichthe outlook was favorable.'^ Gallavardin. amongothers, was interested in the relationship betweenextrasystoles. paroxysms of ventricular tachycar-dia, and ventricular fibrillation.'^ A widely held
view, challenged by Gallavardin. was tbat ven-tricular tachycardia was no more than a successionof extrasystoles. He suggested that although thetwo phenomena were intimately related, tbe samemecbanism might not be responsible for both.'^'^
Experimental ObservationsAt tbe same time that the earliest clinical ob-
servations on ventricular tachycardia were beingdescribed, noteworthy experimental work wasbeing done which was to influence clinical thoughtgreatly. Lewis produced paroxysmal ventriculartachycardia in dogs by ligating either the right orthe left anterior descending coronary artery.'•* Henoted the sequential appearance of single ventric-ular extrasystoles. paroxysmal tachycardia, andfinally ventricular fibrillation in a number of an-imals. He deduced that the tachycardia originatedin the ventricle for several reasons. First, a dis-sociated, slower rhythm was present in the atria
450 May-June 1986 PACE. Vol. 9
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during the tachycardia. Second, vagal stimulationslowed the atrial rbytbm in some cases, but hadno effect on the tachycardia. Finally, he noted tbatspontaneous atrial extrasystoles were followed bya compensatory pause, without interrupting tbetachycardia in any way. Lewis observed that insome animals ventricular tachycardia did not ter-minate spontaneously but ratber degenerated intoventricular fibrillation with an imperceptibletransition between the two rhytbms. Lewis spec-ulated tbat the same might occur in buman heartsand might account for the sudden demise of somepatients. Subsequently. Smith ligated coronaryarteries in dogs using an aseptic technique andallowed the animals to recover,^^ after which beobserved them with repeated electrocardiogramsfor several weeks, He confirmed Lewis' descriptionof the sequence of arrhythmias after experimentalmyocardial infarction, and observed the devel-opment of ventricular fibrillation in some animals,resulting in their death.
Electrocardiographic Features
Electrocardiograpbic criteria for diagnosis ofventricular tachycardia came slowly. Case reportsthat followed Lewis' delineation of ventriculartachycardia did not always exhibit confirmatoryelectrocardiograms. It was not until 1921 thatRobinson and Herrmann attempted to set fortbelectrocardiograpbic criteria for diagnosis of ven-tricular tachycardia: a rapid succession of ven-tricular complexes, distinctly abnormal in form;independent atrial complexes; tbe presence of iso-lated ectopic ventricular beats, before or after tbeparoxysm, identical to those of the paroxysm.^Tbese criteria were generally accepted, and servedas the standard for years after. Robinson andHerrmann were careful to point out that "distur-bance of (ventricular) conduction may appear athigh cardiac rate . . . not apparent when the heartis beating slowly," as Robinson had reported in191fi. ^ This phenomenon, aberrant ventricularconduction or rate-related bundle branch block,posed a stumbling block for those who remainedignorant of it. Several examples of atrial fibrillationwitb rapid ventricular response and aberration orpre-excitation were reported as demonstratingventricular tachycardia.""^°
Tbe next addition to criteria for electrocar-
diograpbic diagnosis of ventricular tachycardiacame many years after Robinson and Herrmann,when Rosenberg as well as Dressier and Roeslerpointed out tbe occasional occurrence of fusionbeats in tracings showing tbe arrbytbmia.^'-^^Esopbageal and pervenous electrodes added in-formation, often unavailable from surface leads,to aid in the diagnosis of ventricular tachycar-^jg 23.24 fyjore recently, information derived fromintracardiac electrophysiological studies has fur-tber refined electrocardiographic criteria for di-agnosis of ventricular tachycardia.^^
Physical Findings
Awareness of the value of findings on physicalexamination that might aid in correct diagnosis ofventricular tachycardia developed slowly and fit-fully. Although independent "A" waves in tbejugular phlebogram were recognized at an earlypoint in time as a feature of ventricular tachycar-dia, interest soon shifted to eloctrocardiograpbicfindings.^'^^ Phlebograpby was superseded by thenewer technique as a diagnostic modality. Interestsin findings in the jugular venous pulse was re-awakened by Prinzmetal and Kellogg in 1934."They reported their observations in a case of ven-tricular tachycardia, reviewed earlier literature,and concluded that evidence of slower, indepen-dent A waves might be encountered in two-thirdsof cases of ventricular tachycardia. Schrire andVogelpoel extended these observations andpointed out that so-called "cannon" A waves wereencountered sporadically in the presence of atrio-ventricular dissociation, but could occur in regularfashion at the same rate as tbe pulse in nodaltachycardias when tbe retrogradely activated atriacontract while tbe atrioventricular valves areclosed.^"
That atrioventricular dissociation, a hallmarkof ventricular tachycardia, might be refiected insystemic blood pressure was first pointed out byWilson et al. in 1964. " Properly timed atrial systoleprovided the "booster pump" effect on ventricularfilling and generated higher systemic pressure thanwben tbe timing was suboptimal. Witb careful re-cording of the blood pressure, it could be dem-onstrated that pbasic waxing and waning of tbepeak systemic pressure provided a useful sign ofatrioventricular dissociation!
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In thR area of auscultation, it was Levine whofirst noted slight irregularity in cycle length in pa-tients with ventricular tachycardia which was au-dible with tho stethoscope.'^ In 1927, he mentionedvariation in intensity of the first heart sound, dueto atrioventricular dissociation, and extendedthese observations in conjunction with Harvey inI94g i9.:io [j -,t,j^^ Harvey and Corrado called at-tention to multiple low-frequency sounds audiblein ventricular tachycardia as a differential point. ^
Prognosis
In 1930, the first large series of patients withventricular tachycardia was compiled by Strauss,who described the clinical characteristics of suchpatients.^^ Using the eleclrocardiographic criteriaof Robinson and Herrmann, Strauss identified 64patients with ventricular tachycardia reported inthe literature in the period between 19t)9 and 1930.He noted that 60% of the cases occurred duringthe fifth and sixth decade of life, with a male pre-ponderance. The diagnosis of myocardiai infarc-tion or angina pectoris had been made in 53 of the64 cases. Congestive heart failure was present intwo-thirds of the patient population and digitalishad been administered before the onset of the
tachycardia in half of the patients. Quinidine sul-fate was acutely successful in controlling parox-ysms in all 16 cases in which it was employed;only three of these 16 cases died during the shortfollow-up period. Strauss correlated prognosis inthis series with the presence or absence of organicheart disease. All 11 case.s without structural heartdisease were living at the time of publication ofhis findings, while 40 of 50 cases wifh organic heartdisease were dead.
Following Strauss' report, a number of otherinvestigators reported large series of patientswith ventricular tachycardia (see Table I). -"" Itis, nonetheless, striking that as recently as 1964,ventricular tacbycardia was described as a dis-tinctly uncommon cardiac arrhythmia.'" As in theseries of Strauss, the typical patient with ventric-ular tachycardia was a man in his fifties or sixtieswith a history of atherosclerotic coronary heartdisease. Greater than half the patients in these se-ries had a prior history of digitalis usage, and insome of these patients digitalis toxicity wasclinically evident.
Most investigators classified ventriculartachycardia into two forms on the basis of patternand duration of the arrhythmia. Interruittenl ven-tricular tachycardia was defined as "runs of ven-
Series {nl.)
1 Strauss**2 Lundy &
McLellan*'3 Williams &
Ellis*"4 Cooke &
White"5 Parkinson &
Papp"6 Herrmann &
Hejtmanclk*'7 Armbrust &
Levine^8 Herrmann et
a l "9 Mackenzie S
Pascual*'10 Leschetal.**
Clinical Characteristics of Patients
#Patients
64
94
36
27
9
20
107
59
8334
Male/Female
43/21
68/26
17/10
4/5
17/3
71/36
34/25
56/2721/13
MeanAge
5O's
46
5O'S
—
—
53
55
60's
5O's2-40
Table 1.
Presenting with Ventricular Tachycardia in
NSHD
11
14
1
5
9
2
13
6
434
CAD
16
29
26
22
0
14
79
42
600
AcuteMl
NA
NA
6
NA
0
8
44
13
310
DigitalisToxicity
32
18(9)
15(5)
—
9(7)
47(13)
33(16)
42(18)
Various Series
CHF
45
31
12
—
15
36
39
Persistent/Intermittent
NA
24/12
14/13
0/9
17/3
82/25
28/31
45/3826/12
Bidirec-tional
18
21
1
4
—
—
3
3
—
NSHD - no structural heart disease identified; CAD = coronary artery disease; Ml = myocardiai Infarction; CHF = congestive heart failure; NA - not available
452 May-June 1986 PACE. Vol. 9
HISTORICAL PERSPECTIVE OF VT
tricular tachycardia separated by periods of nor-mal rhythm, the latter often showing ventricularextrasystoles"^^ or "short paroxysms of tachycar-dia lasting seconds or minutes which ceased spon-taneously or were controlled readily in most caseshy therapy." Persistent ventricular tachycardiawas therehy defined as being of longer durationand without periods of interruption. While thisdistinction appears tenuous, several authors foundimportant differences in prognosis between thesegroups.-'^""'^' In all these series, the prognosis inpatients with no identified organic heart diseasewas strikingly better than in those patients withabnormal hearts. Williams and Ellis commentedthat the prognosis of ventricular tachycardia intheir series was essentially that of the underlyingheart disease.''^-'^
Paroxysmal ventricular tachycardia in youngpatients with otherwise apparently healthy heartswas thought by several investigators to run a be-nign clinical course. -'*^ The frequency of parox-ysms in these patients diminished with time, thenoccurred at long intervals and ultimately disap-peared entirely in a number of patients. Lesch etal. subsequently compiled a series of previouslyreported patients with paroxysmal ventriculartachycardia in the absence of coronary artery dis-ease." In the majority of cases, the patient age atthe time of first presentation was in the teens orearly twenties. Some patients noted an increasedfrequency of arrhythmia either during pregnancyor menstrual periods.
Early investigators assumed the absence ofstructural heart disease if the history, physical ex-amination, chest x-ray, and electrocardiogramwere unremarkahle. The introduction of more re-fined investigations such as cardiac catheteriza-tion, echocardiography, and endomyocardial bi-opsy has demonstrated anatomic and histologicabnormalities in some patients with either "be-nign" ventricular tachycardia or with so-called"primary electrical disease." Ventricular tachy-cardia was found to he associated with such ab-normalities as mitral valve prolapse, myocarditis,and various cardiomyopathies sometimes localizedto small areas of the right ventricle. Although itseems justified that these investigators concludedthat paroxysmal ventricular tachycardia in theabsence of demonstrable heart disease has a goodprognosis, in rare instances such patients died
suddenly." The diagnosis of benign ventriculartachycardia is a retrospective one.
Various investigators attempted to ascribeprognostic significance to morphologic character-istics of ventricular tachycardia. For example,Lundy and McLellan categorized ventriculartachycardia by bundle branch pattern and as-sumed incorrectly the ventricular origin of thetachycardias from these morphologies.^'^ A dis-tinctive form of ventricular tachycardia with beat-to-beat alteration of QRS axis in a single lead hasbeen called "bidirectional" tachycardia and wasfirst described by Schwensen in 1922.'*'' He ob-served its occurrence during atrial fibrillation andlinked it to digitalis intoxication. Palmer andWhite first called attention to its poor prognosis."^The most recent comprehensive review of the re-ported cases (seventy-two to date) was by Cohenet al. in 1973, and included electrophysioiogic datalocalizing the site of origin to the ventricles.*^Cohen and Voukydis subsequently reported a casecompatible with a supraventricular site of origin,and further case reports showed that the site oforigin could be the atrioventricular junction, thefascicular system, the ventricles, or combinationsofthese.**'-' "
The presence of digitalis toxicity was asso-ciated with a poor prognosis, sometimes indepen-dently of whether or not the acute tachycardiareverted. Thus, of seven patients with digitalistoxicity reported by Herrmann and Hejtmancik,six patients had reversion of their ventriculartachycardia acutely but only one was still alivewithin one week; in a separate series of Herrmannet al. 11 of 16 patients with digitalis toxicity diedduring their follow-up period. ^""*
As discussed subsequently, it is difficult inthese series to assess the impact of specific therapy,particularly quinidine sulfate, on the prognosis inthese patients [see Table II). Few patients in theearlier series received specific therapy, and insubsequent series there is no uniformity as to dos-age, mode of administration, or selection of pa-tients for treatment.
Drug TreatmentEarlier reports were concerned with the di-
agnosis of ventricular tachycardia and scarcelyaddressed the treatment of the disorder. Scott in
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McGOVERN. ET AL
Series (Ref.)
Slraoss"Williams & Ellis'*
Cooke & Wtiite*'Parkinson & Papp"Herrmann 4
Heitmancik'*
Armbnjst & Levine"
Herrmann et al**
Mackenzie & Pascual*'
Lesch at al.*^
Known DeadTotal (%)
40/64 (63%)21/36 (58%)
17/27 (63%)1/9 (11%)
11/20 (55%)
45/107(42%)
32/59 (53%)
45/83 (54%)
4/34 (12%)
Table II.
Prognosis of Ventricular Tachycardia
Died DuringTachycardia
NA
8
NA
0
5
12
5
20
NA
Time toDeath
3 hrs-16 rDo20/21 within
1 mo3 hrs-18 mos1 year1 tir-3 tirs (9
dead within1 week)
41 deadwithin 2 mo
28/32 deadwithin 2 mo
36/45 deadwithin 1 mo
NA
Dead/Total (%)ReceivingQuinidine
3/16(19%)7/14(50%)
2/5 (40%)—
8/25 (32%)
8
NA
NA
NA
in Various Large Studies
Dead/Total (%)Without HD
0/11 (0%)0/1 (0%)
0/5 (0%)——
2/13(15%)
2/6 (33%)
0/4 (0%)
4/34(12%)
Dead/Total <%)With HD
40/53 (75%)21/35(60%)
17/22(77%)—
43/72 (60%)
29/53 (55%)
45/79 (57%)
—
Dead/Total (%)intennittent VT
5/12(42%)
1/9 (11%)
—
13/31 (42%)
16/28(47%)
3/26(12%)
Dead/Totai (%)Persistent VT
16/24 (67%)
_
18/18(64%)
29/45 (64%)
1/12(8%)
Abbreviations: HD = identified heart disease; VT = ventricular tachycardia
1922 described a patient in whom exercise reliablyprecipitated episodes of ventricular tachycardia.^'He assessed the effects of several drugs on thetachycardia and found that atropine and epineph-rine precipitated episodes. Quinidine. however,could both terminate and prevent episodes. Scotttreated his patient with quinidine chronically andRffeclivoly for six months. He then readmitted thepatient to the hospital, discontinued quinidine.and observed the recurrence of ventricular tachy-cardia. In addition to his radical use of chronicdrug treatment, Scott observed longer couplingintervals of premature ventricular beats duringtreatment with quinidine and hypothesized thatquinidine abolished ventricular tachycardia bylengthening the refractory period of the ventricle,thereby preventing early premature ventricularbeats. Quinidine had previously been used to treatparoxysmal atrial fibrillation, and was known toprolong Ihe atrial refractory period in dogs. Thislatter work was. for the most part, undertaken byLewis. Drury. and their colleagues.^^ At about thesame time tbat Scott made his clinical observa-tions, Drury and others demonstrated that quini-dine prolonged the refractory period of ventricularmuscle in dogs. ^
Between 1922 and the 1940s, many disparatedrugs were used to treat ventricular tachycardia,generally without a consistent effect being noted.
Quinidine. however, was used increasingly andoften with good effect. " By 1929. Levine and Ful-ton could review their own experience (10 cases)and that of others and advocate the use of quini-dine to terminate paroxysms of ventricular tachy-cardia. " In the course of their paper. Levine andFulton noted some paradoxes concerning ventric-ular tachycardia and its treatment. They observedthat while ventricular tachycardia most often oc-curred in patients with seriously diseased hearts,and that it often preceded ventricular fibrillation.it could also occur in younger people with no ev-idence of heart disease, in which case the prognosisappeared excellent. They also noted thai exercisecould either precipitate ventricular tachycardia orabolish it. The third paradox they described is thattreatment with quinidine could either terminateepisodes of ventricular tachycardia or it couldcause them.
The possibility that ventricular tachycardiacould be precipitated by drugs had been consid-ered earlier by several authors, in particular dur-ing treatment with digitalis or with quinidine. By1950, Armbrust and Levine had followed a largepopulation of patients with ventricular tachycar-dia. '' In this study, quinidine resulted in reversionof persistent ventricular tachycardia in 46 of 57episodes wben given orally, and in 20 of 31 epi-sodes when administered intravenously "in the
454 May-June 1986 PACE, Vol. 9
HISTORICAL PERSPECTIVE OF VT
more desperate cases." Armbrust and Levine con-cluded that Ihe immediate prognosis of a tachy-cardia attack is good when appropriate therapy isadministered. They strongly advocated quinidineadministration in the acute setting, stating that"the fact that the patient becomes nauseated,dizzy, weak, or develops diarrhea or ringing of theears should not discourage the physician frompersisting with this therapy, when the alternativeis likely to be a fatal termination."
Despite the difficulties associated with its use,quinidine remained the mainstay of treatment ofventricular tachycardia for many years. From 1950on. a number of alternative, acutely effectivetreatments were introduced into clinical practice.Procainamide was used to treat ventricular tachy-cardia in man in 1950 and rapidly achieved wide-spread use.'^'*" The first steps toward the devel-opment of procainamide had taken place manyyears earlier. In 1937. Beck and Mantz demon-strated that the topical application of procaine tothe epicardium during surgical procedures re-duced the occurrence of ventricular extrasys-toles.^" Subsequently, procaine was injected intra-arterially and intravenously in patients undergeneral anesthesia.^" Procaine was limited to useunder anesthesia because of its central nervoussystem toxicity. In an attempt to find drugs withthe antiarrhythmic properties of procaine. butwith less toxicity. a variety of chemical substitu-tions were performed in related molecules andmetabolites of procaine. Of these new local anes-thetics, procainamide and lidocaine were toachieve wide clinical use. Within a few years ofits introduction, procainamide was considered bysome a preferable drug to quinidine for terminat-ing ventricular tachycardia, since profound hy-potension was less common after intravenous in-jection.^'As with quinidine. a variety of unwantedeffects were reported during acute and chronicprocainamide usage.
Lidocaine was synthesized in 1946 and wasfirst used clinically by Southworth and colleaguesto prevent ventricular arrhythmias during cardiaccatheterization.'*^ It did not achieve widespreaduse in the United States until the 1960s, at whichtime it became established as the drug of choicefor parenteral use in treating and preventing ven-tricular tachycardia. Other antiarrhythmic drugsquickly followed procainamide and lidocaine.
Phenytoin was first used to treat ventriculartachycardia in 1958, although its anticonvulsantproperties were recognized many years earlior.** '®^In the 1960s a number of other drugs includingbeta-adrenergic blocking agents, disopyramide.bretylium, mexiletine. and amiodarone were re-ported to be effective in treating ventricular ar-rhythmias in selected patients.'^ Recently, an ever-increasing number of new antiarrhythmic drugshave been investigated for clinical efficacy andtolerance.^ Adequate comparative studies of thesedifferent compounds in preventing ventriculartachycardia have not yet been performed.
Cardioversion and Defibrillation
Despite the successful use of antiarrhythmicdrugs to terminate ventricular tachycardia, anumber of important limitations to such an ap-proach are evident. Anliarrhythmic drugs were oflimited efficacy and patients continued to die dur-ing attacks of ventricular tachycardia. In addition,administering drugs to critically ill patients some-times further depressed cardiac output and in-creased the degree of hypotension and myocardialischemia, thus exacerbating an already desperatesituation. Ouce ventricular tachycardia had ac-celerated and become less organized, the likeli-hood of successful termination of the arrhythmiaby drugs became more remote. An alternative,widely applicable and speedy means of terminat-ing rapid heart rhythms was clearly necessary.
Considerable experimental work had dem-onstrated the feasibility of using electric shocks toterminate ventricular fibrillation in a variety ofexperimental situations.''^*''^ In 1947. Beck et al.defibrillated tbe heart of a 14-year-old boy whodeveloped ventricular fibrillation during a thoracicsurgical procedure.*^^ Open-chest massage of tbebeart had been performed for over an hour beforethe heart was defibrillated by passing household110-voIt alternating current between two elec-trodes applied directly to the heart. Procaine hy-drochloride had been injected into the right atriumbefore defibrillation was successfully accom-plished.
In 1956, Zoll et al. succeeded in terminatingventricular fibrillation by applying electric currenttransthoracically iu four patients with cardiac ar-rest.^ Alternating current was delivered between
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McGOVERN, ET AL
two heavily insulated copper electrodes placed atthe level of the apex of the heart: one electrodewas just to the left of tbe sternum, the other at theanterior axillary line. Zoll and his colleagues de-scribed the termination of ventricular tachycardiain one of their patients using this technique, andsuggested that the procedure might be valuable interminating other arrhythmias also. In 1961, Al-exander et al. used alternating current electivelyto terminate ventricular tachycardia that could notbe stopped by giving antiarrhythmic drugs.^^ Overthe subsequent few years, Lown and his colleaguesgreatly refined and popularized techniques forterminating tachyarrhythmias by electric dis-charges.'""" Direct current (DC) or capacitor dis-charge was shown to be safer and more effectivethan alternating current. Synchronization of thedirect current discharge to the R-wave resulted insafer termination of arrhythmias and was called"cardioversion." This was used for arrhythmiasother than ventricular fibrillation. Cardioversionof atrial and ventricular arrhythmias could oftenbe accomplished using 10 joules or less. Ventric-ular tachycardia could occasionally be terminatedby thumping the chest in some patients. "^ Defi-brillation even using DC discharge required muchhigher energies, however. These techniques werequickly accepted around the world and truly rev-olutionized the treatment of cardiac tachyar-rhythmias. Within the past five years, implantabledevices capable of sensing and terminating ven-tricular tachycardia automatically by either defi-brillation or cardioversion have come into clinicaluse." The long-term efficacy and safety of thesedevices is being studied at present.
Overdrive Pacing andVentricular Arrhythmias
In 1960, Zoll and associates reported that in-creasing the heart rate by closed-chest cardiacstimulation had prevented recurrent ventriculartachyarrhythmias for periods of up to 48 hours infive patients with complete heart block.^^ Zoll etal. applied two 3-cm silver electrodes covered withelectrode paste to the anterior chest wall near theapex of the heart. They demonstrated that runs ofventricular fibrillation could be prevented by pac-ing the heart above a certain critical heart rate. Inthe same year, Schwedel, Escber. and Furman
demonstrated similar short-term benefit fromtransvenous right ventricular endocardial pacingin two patients with "bursts of ventricular fibril-lation" and complete heart block." Subsequently,Sowton and colleagues applied a similar techniquein two patients with ventricular tachycardia andfibrillation but without evidence of heart block."Ventricular pacing at rates faster than the intrinsicrhythm apparently prevented episodes of tachy-arrhythmia and extrasystoles in these two patients.Furthermore, these authors suggested that thecombined use of antiarrhythmic drugs and over-drive pacing might be better than the use of eithermodality alone in some patients.
Later, Heiman and Helwig reported on twopatients with ventricular arrhythmias treated byoverdrive atrial pacing.^^ A number of other smallseries with short-term successful treatment of se-rious ventricular arrhythmias were reported in thesubsequent several years.""^^ The technique wasalso applied in patients with ventricular arrhyth-mias following cardiac surgery using wires in-serted into or attached to the heart at the time ofsurgery."^ There have also been a number of fa-vorable reports of the use of permanent cardiacpacing as a longer-term treatment for recurrentventricular arrhythmias in the absence of heartblock."- " ^ These series are small with a limitedfollow-up period. Not all reports were favorable,however. Lown and colleagues, for example, at-tempted overdrive pacing in 12 patients but in nopatient was the technique more than transientlyeffective.^^ It is unclear from these early reportshow many of these tachycardic episodes wouldnow be considered manifestations of the torsadesde pointes syndrome. A number of the electrocar-diograms as well as the clinical settings, such astreatment with agents that prolong the QT interval,strongly suggest that some of these arrhythmiaswere of the torsade pattern (vida infra)."^ Acutetreatment of ventricular arrhythmias by overdrivepacing became accepted as effective in some pa-tients, while the efficacy of long-term treatmentwith implanted pacemakers remains controversial.
Surgical Treatment ofVentricular Tachycardia
In 1959 Couch reported on a patient in whomventricular aneurysmectomy was successfully
456 May-June 1986 PACE. Vol. 9
HISTORICAL PERSPECTIVE OF VT
performed to prevent recurrent ventriculartachycardia."" Subsequent studies in larger num-bers of patients proved disappointing, however.Aneurysmectomy failed to prevent recurrent ven-tricular tachycardia in a majority of patients op-erated on because of drug-resistant arrhythmiaand was associated with a surgical mortality of20-50%."*'™ In recent years, alternative operationsto simple aneurysmectomy have been described.These include incising the margins of an aneurysmin an attempt to wall off the focus of ventriculartachycardia, locating the putative sites of origin ofventricular tachycardia and excising these, andextensive endocardial scar excision combinedwith aneurysmectomy.^'""^
Surgical interventions may aim to treat ven-tricular tachycardia by altering the electrophysi-ologic, neurologic, or hemodynamic milieu inwhich these arrhythmias arise. Sympathectomy,myocardial revascularization, and mitral valvereplacement may be included in this category.**^The long-term benefit of these operations is un-known at present.
Atypical Ventricular Tachycardia
The work of Lewis and others had definedventricular tachycardia as a distinct electro-cardiographic diagnosis. Ventricular fibrillation,however, had been described in animals manyyears earlier and was recognized as an irreversibleterminal rbythm in man. ^^^ Electrocardiogramsshowing ventricular fibrillation were obtained indying patients.^" However, soon after Lewis' paperin 1909, several authors described electrocardio-grams purporting to show transient or sponta-neously terminating ventricular fibrillation.''*^'^""One of these patients suffered recurrent syncopeduring treatment with quinidine and electrocar-diograms recorded during syncopal episodes dem-onstrated paroxysmal ventricular fibrillation.^""One figure published by Kerr and Bender dem-onstrates a rapid, polymorphic ventricular tachy-cardia. Subsequently, a similar arrhythmia wasdescribed by others using a variety of descriptiveterms such as pseudo-fibrillation and cardiac
to describe the cyclical undulating QRS axis ob-served during this arrhythmia (Fig. 2). Additionalfeatures such as marked QT-interval prolongationpreceding torsades, its generally nonsustained na-ture, its association with certain drugs, congenitalabnormalities, bradyarrbythmias. ventricular fi-brillation, and sudden death were recognized.'"^Most importantly, the management of patientswith torsades may be very different than that ofpatients with recurrent monomorphic ventriculartachycardia or fibrillation."''*
Recent Developments
While the clinical application of electrocar-diograms allowed the differential diagnosis of car-diac arrhythmias to be advanced greatly, therewere obvious limitations to its use. Holter and col-leagues were interested in devising methods forobserving patients' heart rhythm while active, andalso for obtaining a longer period of observationof the patient's rhythm, so as to increase the prob-ability of recording a sporadic arrhythmia.'"^ Hol-ter used radio signal transmission to record theheart rhythm of active patients (telemetry). Thisallowed patients to exercise but required them tostay within range of radio-receiving equipment.Subsequently, portable battery-operated electro-magnetic tape recording with high-speed analyz-ing equipment was described by Holter and hasborne his name si nee.'"^
These techniques, with further modifications,came into clinical practice in the 19B0s and havebeen of great value in detecting sporadic andasymptomatic arrhythmias and in defining theirfrequency in different cardiac disease states. Forexample, ventricular tachycardia came to be rec-ognized as a frequently occurring arrhythmia afteracute myocardial infarction.'"^ Holter monitoringtechniques have stimulated much research on theassociation of specific arrhythmias with subse-quent sudden death, and have allowed the re-sponse to a variety of drug treatments of ventric-ular arrhythmias to be more precisely quanti-
Tbe clinical setting in which this arrhythmiaoccurs was best described by Dessertenne in1966.'"^ He used the phrase "torsades de pointes"
Direct intracavitary recordings from tbe hu-man ventricle were reported by Lenegre andMaurice in 1945. and His bundle electrogramswere described by Ciraud, Latour, and Puech in1960.'"^"" It was only in 1969, however, that a
PACE. Vol. 9 May-Iune 1986 457
McGOVERN. ET AL
Figure 2. This gure is from Dessertenne's paper defining torsades de pointes or atypical ven-tricular tachycardia.^"^ Ventricular tachycardia with a shifting axis is shown on three simuJta-neousiy recorded electrocardiographic leads. (Reproduced with permission from Archives desMaladies de Coeur).
safe, percutaneous method of recording the Hisbundle electrogram in man was reported,"^ Thisobservation prompted intense research in record-ing and stimulation techniques for analysis ofcomplex cardiac arrhythmias. In 1972, Wellens etal. reported the initiation and termination of ven-tricular tachycardia in patients with prior ven-tricular tachycardia using critically timed extra-stimuli."^ This ability to initiate and terminate ar-rhythmias under controlled circumstances, as wellas the ability to record from multiple sites withinthe heart, has allowed rapid advancement in ourunderstanding of cardiac arrhythmias. Intracar-diac recordings have allowed more precise diag-nosis of ventricular tachycardia and have modifiedthe electrocardiographic criteria for diagnosingthis arrhythmia.^^ In addition, innovative drug,surgical and electrical treatments for ventriculartachycardia using these techniques have been de-scribed and are currently being evaluated."^
ConclusionsVentricular tachycardia has been shown to
occur in diverse populations and to have a variable
Table III.
Selected Historical Landmarks (1909-1971)
Year
1909
1921
1921
1922194619501956
19571959
1960
1960
196219661971
First electrocardiographic demonstration of ventriculartachycardia.
Relationship of coronary artery disease and ventriculartachycardia described,
Electrocardiographic criteria for ventricular tachycardiawere defined.
Quinidine used to treat ventricular tachycardia.Lidocaine synthesized.Prooainamide introduced into clinical practice.Alternating current used to terminate ventricular
tachycardia.Congenital long QT-syndrome described.Aneurysmectomy performed to treat ventricular
tachycardia.Use of cardiac pacing to prevent ventricular tachycardia
in patients with complete heart block.Elective alternating current termination of ventricular
tachycardia.Synchronized cardioversion" of ventricular tachycardia.Torsades de pointes described.Ventricular tachycardia initiated and terminated by
critically-timed premature ventricular beats.
458 May-Iune 1986 PACE. Vol. 9
HISTORICAL PERSPECTIVE OF VT
outcome. The precise diagnosis of ventriculartachycardia, as well as of the disease states inwhich it is most commonly found, had to awaitIhe development of sensitive instruments to detectand analyze subtle anatomical and physiologicperturbations. Our knowledge of ventriculartachycardia is inadequate because of the limita-tions of these very instruments. The natural his-tory of ventricular tachycardia is often unknown,because of imprecise diagnosis, random treat-ments, and such confounding factors as digitalis
toxicity. Many treatments have been used, somedramatic and life-saving, hut the efficacy of othertreatments remains unclear. The pace of researchin the field is rapid, however, and greater under-standing and more effective treatments for ven-tricular tachycardia can be anticipated.
Arknoiviedgmenl: The authors thank Joanne Melesciuc forexcellent secrelarial lieip wilh this manuscript.
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