RISK OF A-V BLOCK DURING SURGERY/Pastore et al.

pathway in reciprocal tachycardia. Observations in patients with andwithout the Wolff-Parkinson-White syndrome. Circulation 52: 58, 1975

4. Gallagher JJ, Gilbert M, Svenson RH, Sealy WC, Kasell J, Wallace AG:Wolff-Parkinson-White syndrome. The problem, evaluation, and surgicalcorrection. Circulation 51: 767, 1975

5. Durrer D, Roos JP: Epicardial excitation of the ventricles in a patientwith Wolff-Parkinson-White syndrome. Circulation 35: 15, 1967

6. Cobb FR, Blumenschein SD, Sealy WC, Boineau JP, Wagner GS,Wallace AG: Successful surgical interruption of the bundle of Kent in apatient with Wolff-Parkinson-White syndrome. Circulation 38: 1018,1968

7. Tonkin AM, Miller HC, Svenson RH, Wallace AG, Gallagher JJ:Refefractory periods of the accessory pathway in the Wolff-Parkinson-White syndrome. Circulation 52: 563, 1975

8. Svenson RH, Miller HC, Gallagher JJ, Wallace AG: Electrophysiologicevaluation of the Wolff-Parkinson-White syndrome. Problems in assess-ing antegrade and retrograde conduction over the accessory pathway.Circulation 52: 552, 1975

9. Denes P, Wu D, Dhingra R, Pietras RJ, Rosen KM: The effect of cyclelength on cardiac refractory periods in man. Circulation 49: 32, 1974

10. Wellens JHH, Durrer D: Wolff-Parkinson-White syndrome and atrialfibrillation. Relation between refractory period of accessory pathway andventricular rate during atrial fibrillation. Am J Cardiol 34: 777, 1977

11. Batsford WP, Akhtar M, Caracta AR, Josephson ME, Seides SF,Damato AN: Effect of atrial stimulation site on the electrophysiologicalproperties of the atrioventricular node in man. Circulation 50: 283, 1974

12. Damato AN, Caracta AR, Akhtar M, Lau S: The effects of commonlyused cardiovascular drugs on AV conduction and refractoriness. In HisBundle Electrocardiography and Clinical Electrophysiology, edited byNarula OS. Philadelphia, F A Davis Company, 1975, pp 105-127

13. Gallagher JJ, Pritchett ELC, Sealy WC, Kasell J, Wallace AG: The pre-excitation syndrome. Prog Cardiovasc Dis (Jan 1978)

14. Smith WM, Pritchett ELC, Campbell RWF, Gallagher JJ: An interac-tive computer program for measurement of data obtained using the extra-stimulus technique during electrode catheter studies. Comput BiomedRes December 1977

15. Wit AL, Weiss MB, Berkowitz WD, Rosen KM, Steiner C, Damato DN:

Patterns of atrioventricular conduction in the human heart. Circ Res 27:345, 1970

16. Wellens HJJ: Effect of drugs on Wolff-Parkinson-White syndrome. InHis Bundle Electrocardiography and Clinical Electrophysiology, editedby Narula OS. Philadelphia, F A Davis Company, 1975, pp 367-386

17. Morris A, Cohn K, Scheinman MM: Right atrial versus left atrial echozones: A proposed new criterion for determining the atrial site of retro-grade preexcitation. J Electrocardiography 9: 357-363, 1976

18. Pritchett ELC, Gallagher JJ, Wallace AG: Reentry within the atrio-ventriculo-node in man. A reassessment. European J Cardiol (In Press)

19. Denes P, Wu D, Amat-y-Leon F, Wyndham C, Simpson R, Dhingra R,Rosen K: The effect of propranolol on anomalous pathway refractorinessand circus movement tachycardia in patients with preexcitation. Am JCardiol 39: 319, 1977

20. Rosen KM: A-V nodal reentrance: An unexpected mechanism of parox-ysmal tachycardia in patients with preexcitation. Circulation 47: 1267,1973

21. Wellens HJ, Durrer D: Effect of digitalis on atrioventricular conductionand circus-movement tachycardia in patients with Wolff-Parkinson-White syndrome. Circulation 47: 1229, 1973

22. Mandell WJ, Laks MM, Obayashi K, Hayakawa H, Daley W: TheWolff-Parkinson-White syndrome: Pharmacologic effects ofprocainamide. Am Heart J 90: 744, 1975

23. Wellens HJJ, Durrer D: Effect of procaine amide, quinidine, andajmaline in the Wolff-Parkinson-White syndrome. Circulation 50: 114,1974

24. Sellers TD Jr, Campbell RWF, Bashore TM, Gallagher JJ: Effects ofprocaine amide and quinidine sulfate in the Wolff-Parkinson-White syn-drome. Circulation 55: 15, 1977

25. Sung RJ, Castellanos A, Gelband H, Myerburg RJ: Mechanism ofreciprocating tachycardia during sinus rhythm in concealed Wolff-Parkinson-White syndrome. Circulation 54: 338, 1976

26. Josephson ME, Seides SF, Damato AN: Wolff-Parkinson-White syn-drome with 1:2 atrioventricular conduction. Am J Cardiol 37: 1094, 1976

27. Wellens HJJ, Lie KI, Bar FW, Wesdorp JC, Dohmen HJ, Duren DR,Durrer D: Effect of amiodarone in the Wolff-Parkinson-White syndrome.Am J Cardiol 38: 189, 1976

The Risk of Advanced Heart Block in Surgical Patientswith Right Bundle Branch Block and Left Axis Deviation

JOHN 0. PASTORE, M.D., PETER M. YURCHAK, M.D.,KENNETH M. JANIS, M.D., JOHN D. MURPHY, M.D., LEONARD M. ZIR, M.D.

SUMMARY The risk of advanced atrioventricular block duringanesthesia was studied prospectively in 44 patients with right bundlebranch block and left axis deviation who underwent a total of 52operations over a 14 month period. All patients had continuous elec-trocardiographic monitoring throughout anesthesia induction, opera-tion, and surgical recovery. Of the 52 operative procedures, 24 weredone under general anesthesia, 11 under spinal, and 17 under local.The preoperative cardiac rhythms were atrial fibrillation in twopatients, atrial tachycardia with block in one patient, atrial flutter in

ALTHOUGH PATIENTS who develop complete heartblock commonly have preceding complete right bundlebranch block and left axis deviation on the electrocardio-gram, the incidence of progression to complete heart blockin prospective studies of patients. with this form of

From the Departments of Internal Medicine (Cardiac Unit) andAnesthesia, Massachusetts General Hospital, Boston, Massachusetts.

Address for reprints: Leonard M. Zir, M.D., Cardiac Unit, MassachusettsGeneral Hospital, Boston, Massachusetts 02114.

Dr. Pastore's present address is Cardiology Division, St. Elizabeth'sHospital, 736 Cambridge Street, Brighton, Massachusetts 02135.

Received August 29, 1977; revision accepted November 28, 1977.

one patient, and sinus rhythm in the remaining patients. Temporarypacemakers were inserted preoperatively in six patients, usuallybecause of PR interval prolongation on the preoperative electrocar-diogram. There was only one episode of transient complete heartblock in 51 of the 52 operative procedures. In two of the six patientswith temporary pacemakers, significant pacer-related ventricularirritability occurred. This study indicates that temporary pacemakerinsertion is rarely required in patients with chronic right bundlebranch block and left axis deviation who require noncardiac surgery.

bifascicular block appears to be less than 10%.'-4 Car-diologists at our hospital are frequently consulted on thequestion of standby cardiac pacemaker placement whenpatients with this electrocardiographic abnormality requiresurgery. The assumption has been that the stress ofanesthetic induction and surgery might predispose patientswith complete right bundle branch block and left axis devia-tion to advanced heart block.We have recently followed prospectively through surgery

a number of such patients in an attempt to determine the in-traoperative risk of their developing advanced atrioventric-

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ular block. Our aim was to determine the need forprophylactic temporary pacemaker insertion in suchpatients.

Methods

Over the 14 months between July 1973 and September1974, all tracings received in the ElectrocardiographicLaboratory at the Massachusetts General Hospital werescreened for the presence of right bundle branch block withleft axis deviation. To satisfy our criteria for right bundlebranch block, the QRS duration in one of the standard leadshad to be at least twelve hundredths of a second, and therehad to be an rSR' complex in lead VI. Left axis deviationwas defined as an axis at or more leftward than -30 degreesin the absence of standard criteria for inferior myocardial in-farction. Patients whose conduction pattern fit these criteriawere considered to have bifascicular block.3Those patients about to have surgery other than cardiac

surgery were identified and followed. Each patient had atwelve lead electrocardiogram taken as soon before and asearly after surgery as feasible. In most cases, these full elec-trocardiograms were taken in the operating room.

All patients had continuous single lead ECG monitoringthroughout their surgical procedures and in the recoveryroom. In addition, all patients requiring general anesthesiawere monitored through induction, intubation, and extuba-tion as well. All patients with preoperative electrocardio-grams revealing first degree atrioventricular block beforegeneral anesthesia had standby temporary pacemakersplaced preoperatively. In each case, a Cordis bipolar pacingelectrode was inserted percutaneously through a subclavianvein with the tip positioned in the right ventricular apex.This was usually done under direct fluoroscopic visualiza-tion. The pacemaker generators were always turned off dur-ing surgery.

Patients with normal PR intervals were observedthroughout surgery, with cardiac pacemaking equipmentavailable in the operating room.

Results

Over the 14 month period of study, 44 patients with rightbundle branch block and left axis deviation underwent atotal of 52 operations at the Massachusetts GeneralHospital and the Massachusetts Eye and Ear Infirmary. Ofthese 44 patients, 35 were men and nine were women. Theyranged in age from 40 to 91 years, with a mean age of 73years. The duration of bifascicular block was unknown inmost cases, being definitely greater than three months in 14patients, but definitely greater than one year in only eightpatients studied.One patient gave a history of syncope, that episode oc-

curring more than one year before her operation. Elevenpatients of the 44 gave a history of angina pectoris, but onlythree had a clinical history of myocardial infarction. An ad-ditional three patients had presumptive evidence of previousanterior wall myocardial infarction on the electrocardio-gram on the basis of anteroseptal Q waves.

Table I shows the prevalent cardiac rhythms as well as theform of anesthesia administered during the 52 surgicalprocedures. On the preoperative tracings, two patients were

TABLE 1. Atrial Rhythm Patterns and Forms of AnesthesiaAdministered During the 52 Operative Procedures

Anesthesia TotalRhythm General Spinal Local operations

Sinus (normal PR) 18 6 12 36Sinus (prolonged PR) 4 4 4 12Atrial fibrillation 1 1 2Atrial tachycardia

with block 1 1Atrial flutter 1 1

Total operations 24 11 17 52

in atrial fibrillation, one in atrial flutter, and one in atrialtachycardia with variable A-V block. The latter patient wasnot receiving digitalis. Of the 40 patients in normal sinusrhythm, eight had PR intervals greater than 0.20 seconds.

There were no episodes of advanced heart block or signifi-cant arrhythmias during intubation and surgery in 51 of the52 operative procedures. Transient complete heart block oc-curred in one patient during intubation (fig. 1). This patienthad a normal PR interval on the preoperative electro-cardiogram. A temporary pacing monitor was placed, andthe operation (a hip replacement) proceeded without furtherincident.Temporary pacemakers were implanted prior to general

anesthesia in six patients. A temporary pacemaker wasplaced in five patients because of a prolonged PR interval,and in one patient because of transient complete heart blockinduced by carotid sinus massage. No episodes of completeheart block occurred in the six patients with temporarypacemakers. However, in two of the patients, significantventricular irritability occurred in the immediate post-operative period (fig. 2). The ventricular irritability resolvedin both patients upon removal of the temporary pacemakers.In both cases the temporary pacemaker had been previouslyplaced with fluoroscopic guidance.

There were no significant differences between preopera-tive and postoperative electrocardiograms. Only minorchanges in heart rate, axis deviation, and PR intervals werenoted.

There were no immediate operative deaths. Three patientsdied in the late postoperative period, with none of the deathsattributable to advanced heart block.

Discussion

This study was undertaken to determine the need for tem-porary pacemakers in surgical patients with right bundlebranch block and left axis deviation. At the MassachusettsGeneral Hospital, which has 350 surgical beds, this form ofbifascicular block is relatively common, and is encounteredapproximately 50 times a year among patients beingscreened for noncardiac surgery. The results of our study in-dicate that the routine preoperative placement of cardiacpacemakers in patients with right bundle branch block andleft axis deviation who are going to surgery does not seem tobe justified. The risks of advanced atrioventricular blockwould appear to be low, and the hazards of temporarypacemaker insertion and maintenance in these patients is afactor to be considered.The single patient who advanced to complete atrioventric-

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RISK OF A-V BLOCK DURING SURGERY/Pastore et al.

Lead Xl

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ular block did so during intubation. The progression to com-plete block occurred by a type I mechanism since there wasdefinite PR interval prolongation prior to block. This ispresumptive evidence that the block involved the A-V noderather than the remaining left posterior fascicle.' Hencenone of the patients in this series progressed to completeheart block by a type 1I mechanism.

If patients with right bundle branch block and left axisdeviation are at risk of developing advanced block duringsurgery, it would appear that the risk is greatest during theparasympathetic discharge which accompanies intubation.However, it is doubtful that this parasympathetic dischargeand the bradycardia which it produces are more common inpatients with bifascicular block than in those with com-

FIGURE 1. A rhythm strip (lead II) during intuba-tion in patient A. C. demonstrates sinus slowing, sinusarrest, and high-grade atrioventricular block.

pletely normal conduction. It can usually be avoided ifemphasis is placed upon performing as smooth an inductionand intubation as possible. Should increased vagal tone oc-cur, it appears to be both brief and self-limited. The cautioususe of atropine sulfate may be indicated in selected cases.

Prior studies in the need for prophylactic temporary pac-ing in patients with bifascicular block undergoing noncar-diac surgery have either been retrospective or involved asmall number of patients. Berg et al.6 studied in retro-spective fashion the medical records of 30 patients with"bilateral bundle branch block" who underwent 36 surgicalprocedures. Twenty-six of their patients had right bundlebranch block and left axis deviation, the remaining four hav-ing left bundle branch block and first degree heart block.

j>iIs.08Al;. :l+S$a

V3

A.C. 40M116-28-23

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FIGURE 2. Electrocardiographic leads V3 and VS in patient A,C. demonstrate ventricular tachycardia.

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VOL 57, No 4, APRIL 1978

There were three postoperative deaths, which the authorsfelt were not attributable to advanced heart block. Onepatient developed regular bradycardia at 40 beats perminute immediately postoperatively. An ECG was inter-preted as showing sinus bradycardia, and the pulsequickened following the intravenous administration ofatropine sulfate. The authors concluded that "although theimpression of the physicians in attendance was that of avasovagal reaction to the pain in anesthesia, transient com-plete heart block could not be ruled out."Venkataraman et al.7 studied retrospectively 38 patients

with right bundle branch block and left anterior hemiblockwho underwent surgical or endoscopic procedures from1968-1973. Seven patients had additional first or seconddegree atrioventricular block. The authors report that two ofthese seven developed bradyarrhythmias requiring treat-ment. Preoperative treatment with atropine, digitalis, or an-tiarrhythmic agents did not affect the incidence of thesecomplications. They concluded that in patients having rightbundle branch block with left anterior hemiblock and first orsecond degree atrioventricular block "pacemaker insertionmay be warranted." The form of bradyarrhythmiasdeveloped by this subset of patients is not specified in theirpaper.

Kunstadt et al.8 studied prospectively 24 patients with"bifascicular block" who underwent 38 operations, 21 of the24 subjects having right bundle branch block and leftanterior hemiblock. Of the 38 operations, 13 were per-formed after insertion of a prophylactic pacemaker. Con-stant intraoperative ECG monitoring did not disclose anyepisodes of advanced atrioventricular block. There were nocomplications due to insertion of the temporarypacemakers, which in their institution are introduced via thefemoral or antecubital vein. His bundle recordings were per-formed in three patients with bifascicular block who un-derwent surgery, and the results of the His studies appear tobe noncontributory.

Escher9 has cited a low risk of temporary pacemaker in-sertion and maintenance using the subclavian route. In addi-tion, she argues that tip malposition is not a problem if thepacer is implanted with fluoroscopic guidance. However, wefeel that the unconscious surgical patient who is beingpositioned and transported with a temporary pacemaker inplace may be at increased risk of dislodgement of thepacemaker tip from the right ventricular apex into the rightventricular cavity, where it can produce ventricularirritability.Few of our patients had a long PR interval, and our find-

ings cannot be extrapolated to the subset of patients withthis additional abnormality. Similarly, we have not studied

the effects of surgical stress upon patients with right bundlebranch block and right axis deviation. Recent work wouldindicate that the rate of development of complete heartblock among the latter patients is low,'" but the effects ofsurgical stress on a large series of these patients remain to bestudied.At the present time, we continue to recommend the

preoperative placement of temporary pacemakers inpatients with the additional history of syncope, unstableangina pectoris, or a recent myocardial infarction. The riskof advanced block in patients with bifascicular block andacute ischemia is well documented," and our findings do notnegate those data. The significance of PR interval prolonga-tion remains unsettled, as we have indicated, and we con-tinue to recommend standby pacemakers in patients withthis additional problem. This policy may be overly cautiousand could change as we gain adequate experience with thissubgroup of patients.

Clearly, as a minimal precaution, all patients with rightbundle branch block and left axis deviation should have con-tinuous ECG monitoring throughout operative or peri-operative procedures which are likely to stress the conduct-ing system of the heart.

Acknowledgment

We wish to thank Ms. Diana L. Wilcox for typing this manuscript.

References1. Lasser RP, Haft JI, Friedberg CK: Relationship of right bundle branch

block and marked left axis deviation to complete heart block and syn-cope. Circulation 37: 429, 1968

2. Denes P, Dhingra RC, Wu D, Chuquimia R, Amat-Y-Leon F, WyndhamC, Rosen KM: H-V interval in patients with bifascicular block (right bun-dle branch block and left anterior hemiblock). Am J Cardiol 35: 23, 1975

3. Rosenbaum MB: The hemlblocks: Diagnostic criteria and clinicalsignificance. Mod Concepts Cardiovasc Dis 34: 141, 1970

4. DePasquale, Bruno MS: Natural history of combined right bundlebranch block and left anterior hemiblock (bilateral bundle branch block).Am J Med 54: 297, 1973

5. Barold SS, Friedburg HD: Second degree atrioventricular block. Am JCardiol: 311, 1974

6. Berg FR, Kotler MN: The significance of bilateral bundle branch blockin the pre-operative patient. A retrospective electrocardiographic andclinical study in 30 patients. Chest 59: 62, 1971

7. Venkataraman K, Madias JE, Hood WB: Indications for prophylacticpre-operative pacemakers in patients with right bundle branch block andleft anterior hemiblock. Chest 68: 501, 1975

8. Kunstadt D, Punja M, Cagin N, Fernandez P, Levitt B, Yuceoglu YZ:Bifascicular block: A clinical and electrophysiologic study. Am Heart J86: 173, 1973

9. Escher DJW: Types of pacemakers and their complications. Circulation47: 1119, 1973

10. Dhingra RC, Denes P, Wu D, Chuquimia R, Amat-Y-Leon F, WyndhamC, Rosen KM: Chronic right bundle branch block and left posteriorhemiblock. Clinical, electrophysiologic and prognostic observations. AmJ Cardiol 36: 867, 1975

11. Rotman M, Wagner GS, Wallace AG: Bradycardias in acute myocardialinfarction. Circulation 45: 703, 1972

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J O Pastore, P M Yurchak, K M Janis, J D Murphy and L M Zirleft axis deviation.

The risk of advanced heart block in surgical patients with right bundle branch block and

Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1978 American Heart Association, Inc. All rights reserved.

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