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Response to Exercise in CongenitalComplete Atrioventricular BlockBy DANAE IKKOS, M.D., AND JOHN S. HANSON, M.D.

T HE CLINICAL and hemodynamic find-ings in patients with complete heart block

have been reported by many authors.1-14 Thereis general agreement that irrespective of theetiology of the block, cardiac enlargement andincreased stroke volume are the compensatorymechanisms for the slow rate. In a few studiesventricular rate and other hemodynamicchanges have been followed during exer-cise.1-3' 13-15 The prevailing opinion is that inpatients with the congenital form of completeheart block the ventricular rate increasesmore readily than in patients with the ac-quired form of the arrhythmia. This opinionis based principally on observations in isolatedcases. Therefore, the effect of exercise andexercise tolerance were studied in patientswith the congenital form of complete atrio-ventricular dissociation.

Materials and MethodsThe present studies were conducted in 11 such

patients ranging from 7 to 23 years of age. Diag-nosis of congenital A-V block had been made ininfancy or early childhood in all patients. Ex-haustive histories had failed to disclose any in-fective, toxic or other bases for the suppositionthat the blocks might be acquired rather thancongenital. None of the patients had subjectivecardiac symptoms, including Stokes-Adams at-tacks.

Exercise tolerance tests were performed on anelectrically braked bicycle ergometer* for 2 6-minute periods. The work load during the firstperiod was approximately half the submaximalworking capacity as predicted on the basis of the

From the Department of Cardiology, PediatricClinic, Caroline Hospital, Stockholm, Sweden.

This work wvas carried out during the tenure ofa Postdoctoral Research Fellowship (Dr. Hanson)of the National Heart Institute, U. S. Public HealthService, Bethesda, Md.

Presented in part before the Cardiology Sessionof the IX International Congress of Pediatrics,Montreal, Canada, July 1959.

*Manufactured by Elema Corporation, Stockholm,Sweden.

Circulation, Volume XXII, October 1960

patient's physical characteristics (sex, age, andbody weight).21 During the second period the fullload was applied. In the usual calculation of thesubmaximal working capacity the load causing apulse frequency of 170 per minute at a relativelysteady state is taken as the desired value.'6 17 Inthe present series such a reference value couldnot be obtained because of the patients' cardiacarrhythmia. Therefore, in duplicate determina-tions each subject was asked to perform exerciseat increasing loads up to his limit of tolerance.The highest work load tolerated was arbitrarilytaken as the submaximal working capacity. Dur-ing exercise additional correlative signs proposedby others14 such as atrial heart rate and electro-cardiographic changes were followed.A standard 12-lead electrocardiogram was re-

corded at rest. During exercise the electrocardio-gram was obtained by placing the indifferentelectrode on the forehead. Heart volume was de-termined radiologically by means of biplane, rightangle radiographs.18 19 Predicted normal valuesin standing position were calculated according toMaurea.20 Total amount of hemoglobin was de-termined by the alveolar carbon monoxide meth-od22 with certain modifications.23 Total blood vol-ume was calculated from total hemoglobin andhemoglobin concentration. Right heart catheteri-zation was performed according to methods pre-viously described from this laboratory.24 Oxygencontent and capacity of blood samples were de-termined by Van Slyke manometric apparatus,while oxygen saturation of cardiac catheter sam-ples was determined in a Kipp Haemoreflectoraccording to Brinkman.25

ResultsThe primary data colicerning heart size,

working capacity, electrocardiographic find-ings, and total amount of hemoglobin as wellas atrial and ventricular rates before, during,and after exercise are presented in table 1.The heart size, relative to body size, is pre-sented graphically in figure 1. Since the ageand body size of the patients varied widely,the relative heart size is presented as the dif-ference between the found heart volume (instanding position) and the one predicted onthe basis of the data of Maurea,20 the difference

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Figure 1Heart volume, ml., (in standing position) in rela-tion to body size, expressed as the difference be-tween observed and predicted values inCa-units;predicted values from Maurea et al.20

being expressed in standard deviation units.Definite cardiac enlargement was found in 5of the 11 eases. In figure 2 the heart size(heart volume in prone position) is plottedagainst the total hemoglobin. When this refer-enee standard was used definite cardiac en-largement was present in 7 of 10 cases.

Figure 3 shows that the patients' physicalworking capacity was not correlated to theirheart size and that in 6 of 10 patients work-ing capaeity was normal, being only slightlyreduced in 4.During work all patients showed increases

in both atrial and ventricular rates (fig. 4).In 6 cases extrasystoles appeared during exer-cise, and in 3 of these 6 bigeminy or trigeminywas observed during short periods, usually atthe maximal load. One patient, accustomed tostrenuous exercise and with a ventricular rateof 36 to 40 per minute at rest, developed bi-geminy and trigeminy during the second workload. This disappeared during continued exer-eise, and a ventricular rate of 130 per minutewas present at the end of the work period.The ventricular rates observed during exer-


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EXERCISE IN ATRIOVENTRICULAR BLOCK

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Figure 2Heart volume, ml., (in prone position) in relationto total amount of hemoglobin. Normal values andtheir + 2o limits from the data of Holmgren etal.29

Working cap.in °% ofnormal meanvalue 130-

120-110-

100-90-

80-70-60-

0

0

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-16 X +16 +2d +36 Heart size

Figure 3Working capacity in per cent of the normal value(normals from Bengtsson21) related to heart sizeexpressed in standard deviations.

cise, disregarding periods with extrasystoles,varied between 68 and 130 per minute. No cor-

relation between the ventricular rate at restand that during exercise was established (fig.5). Nor was there any correlation betweenheart size and ventricular rate (fig. 6). Whenthe exercise was stopped, extrasystoles disap-peared immediately in 4 patients and within1 minute in another. In the sixth instancethe bigeminy, which appeared during the test,persisted for 5 minutes after exercise. Thisparticular patient had at the same time a sino-atrial block and demonstrated the largest de-


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Figure 4Atrial and ventricular rates at rest, during andafter exercise.

gree of heart volume increase observed in thepresent group. Because of the sinoatrial blockthis patient has been excluded from figures5, 6, 7, and 10.The relative increase in the atrial and ven-

tricular rates during exercise are shown infigure 7. The former increased almost stepwiseat increasing work loads, but a stepwise in-crease in ventricular rate was found in onlya few cases. In several instances the maximalventricular increase occurred between restand the first load, while in others it was ob-served during the second load.Although it was previously assumed14 that

in congenital heart block the relation betweenthe atrial and ventricular rates remained un-changed by exercise, this was not, however,the case in our material. Changes in the ratioof atrial-ventricular rates were observed inevery case, being pronounced in 3, both dur-ing (fig. 8) and after exercise (fig. 9).The relation between the gain in the atrial

and ventricular pulse rate during exercise (inper cent of the rate at rest) is presented infigure 10. The present findings demonstrate aclear positive correlation between these 2 va-riables, the gain in the ventricular rate in-

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VENTRICULAR RATE

Exercise130-

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Figure 5The relation between the ventricular rates at restand exercise.

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Figure 6Relation between ventricular rate at rest and exer-cise and relative heart size (expressed in S.D. fromnormal).

creasing parallel with the gain in the atrialrate.Upon cessation of exercise atrial and ven-

tricular rates decreased and returned almostto previous values within 10 minutes (fig. 4).The rapidity with which this decrease oc-curred was, however, not always the same forthe 2 rates. In most instances the ventricularrate decreased more rapidly than the atrialas is shown by the increase in the atrial-ven-tricular ratio 1 minute after exercise (fig. 9).

Cardiac catheterization was carried out in4 of the 11 subjects, evidence of an atrial septaldefect being found twice (table 2). All right

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Figure 7The change in atrial and ventricular rates duringexercise.

atrial, right ventricular, and pulmonary ar-

tery pressures were normal in the 2 patientswithout atrial septal defect, and response toexercise during catheterization was deter-mined in these instances (fig. 11). Presenceof increased cardiac output, stroke volume,and a widened A-V oxygen difference was

confirmed during exercise.

DiscussionThe calculation of the working capacity of

patients with atrioventricular block with theexercise tolerance test utilized presents some

difficulties. In patients without arrhythmiasthe working capacity corresponds to the sub-maximal work load, i.e., the load which at a

steady state causes a pulse frequency of 170per minute.'6' 17 It is evident that such rates


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1A

1.2

ratio auricular: ventricular rate

0 during restA during exercise

3.00-

2.00-

1.00-

Figure 8Changes in the ratio of atrial :ventricular ratesduring exercise.

could not be obtained in patients with con-

genital atrioventricular block. Therefore inthe present study the work load that couldbe tolerated by the patients was taken as thesubmaximal work load and compared to theone predicted for each case. Holmgren et al.14have suggested that the atrial rate insteadof the ventricular rate should be used incases with atrioventricular block. From theresults in table 1 it is obvious that the sub-maximal working capacity as determinedabove meets the criteria of Holmgren et al.In all patients but 1 (case 2) the atrial rateduring the second work load was around 170per minute (range 160 to 185).That patients with congenital atrioventrie-

ular block have a normal or nearly normalworking capacity in a standardized exercisetolerance test demonstrates that this cardiacarrhythmia is not in itself an ineapacitatingdisease, at least in the age range studied. Notonly are such patients able to cope with themuscular activity of everyday life withoutsymptoms, but they can also tolerate strenu-ous muscular exercise. For example, patients3, 6, 7, and 9 were engaged in usual athleticsand patient 4 was an ardent ice-hockey player.Circulation, Volume XXII, October 1960

Figure 9The change in ratio of atrial :ventricular ratesduring recovery following exercise.

Similar isolated examples have been pre-

viously reported in the literature.15 26

The ventricular acceleration during exerciseobserved in these patients with atrioventrieu-lar block shows that this circulatory adjust-ment, which is the most important one duringphysical effort in normal people, is also ofimportance in such patients.The maximal ventricular rate obtained

during exercise at submaximal working loadshowed large individual variations (table 1,fig. 4). Gilchrist3 studied the effect of a stand-ard exercise tolerance test on the atrial andventricular rates in patients with acquiredcomplete heart block and found a negativecorrelation between the atrial and ventriculargains during exercise. He therefore suggestedthat the Bainbridge reflex was of importancein the large atrial gain with small ventricularacceleration during exercise. Our observationsof a positive correlation (fig. 10) are, how-ever, opposite to his. The much larger ventric-ular accelerations in our patients gave us

observations in a different range from Gil-christ's that are not comparable. The differ-ence in myocardial competence between hiselderly patients and our young ones may well

Duri ng After exerciseexercise 1 mi 5 mi 10 mi

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0

0

6 0 70 80 90 100 110 120 130Auricutar gain( in */. of the rate at rest )

Figure 10Correlation between increases in atrial and ven-tricular rates during exercise.

account in large part for the amount of exer-cise tolerated, in ventricular acceleration, andin the ratios of atrial-ventricular gains.The factor that determnined the maximal

ventricular rate was not the rate at rest northe heart size, since no correlation could bedemonstrated between these variables and themaximum venltricular rate (figs. 5 and 6).Furthermore, although the ventricular andatrial rates increased, by and large, in parallel(fig. 4), the agreement between these increaseswas not complete. The atrial-ventricular ratioshowed changes both during transit from restto exercise and from exercise to rest (fig. 9).These changes were very pronounced in a fewcases (fig. 8). The reason for these changesin atrial-ventricular ratio is demonstrated infigure 7. The atrial rate increased in a normalmanner, i.e., stepwise, while the increase inthe ventricular rate was irregular in the sensethat it occurred in many cases either betweenthe rest and the first load or between the firstand second load.Although it might be postulated that the

occurrence of ventricular extrasystoles, eitherisolated or in the form of bigeminy or tri-geminy, could be a factor in increasing cardiacoutput, this does not seem to be the case.Holmgren14 has demonstrated decreases inmean arterial pressure during periods of bi-geminal rhythm. As the increase in ventricu-lar rate produced by exercise is limited in

11265

240

21570480

70 90 110 50 70 90Puls. rate

Figure 11Hemodynamic findings in 2 cases at cardiac cathe-terization during rest and exercise.

these cases, however, other hemodynamicchanges must take place to effect maintenanceof a normal exercise toleranee, despite therelative bradyeardia. Measurement of theheart size in the present group confirmed pre-vious findings of others that cardiac enlarge-ment is present in atrioventricular block. Thisincrease in heart size permits normal minutevolumes by increasing stroke volume'1 12 andthus aids in supporting a normal or nearlyniormal working capacity (fig. 1). The impor-tance of cardiac enlargement as a compensa-tory mechanism in atrioventricular block haseven been experimentally demonstrated.Starzl et al.27' 28 found that dogs with experi-mentally produced atrioventricular blocks re-

Circulaiton, Volume XXII, October 1960

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Table 2Findings at Rtght Heart Catheterization

Q -s

Case Pressures in mm. Hg -', .p op P w cno. RA RV PA BA Wedge O : O¢ - Z u2 -

5 4 28/3 26/4 80/45 6 97 40 4.8 100 78 48 Rest94 10.5 156 158 67 Exercise

7 5 33/6 29/6 110/57 - 99 40 4.8 90 113 54 Rest77 8.8 80 166 110 Exercise

8 5 54/9 - 85/35 8 96 33 R 6.3 R 146 83 43 Rest(ASD) L 4.5 L 104

10 5 43/6 38/8 95/7 (L.V.) - 94 40 R 11.0 R 203 103 54 Rest(ASD) L 4.5 L 83

gained their preoperative working capacity afew months later when cardiac enlargementand increased stroke volume were obvious.

In 2 patients of our group the hemodynamicadjustments to exercise were observed duringcardiac catheterization (fig. 11). The resultsclearly show the interplay between heart vol-ume, ventricular rate, and stroke volume insuch cases. The first case was a 12-year-old girlwith normal heart size. The cardiac outputduring work increased from 4.8 to 8.8 litersper minute by virtue of an increase in ven-tricular rate from 53 to 110 per minute, thestroke volume remaining practically unchang-ed. Even the A-V oxygen difference waswithin the normal range for the changesin heart rate. An increase in cardiac outputwas also seen in the second patient, a girl of15 years. But here the increase of minute vol-ume from 4.8 to 10.5 liters per minute wasachieved principally through a 50 per centincrease in stroke volume, the ventricular rateincreasing only slightly from 48 to 68 perminute. In this case another hemodynamicadjustment was recognized, the A-V oxygendifference increasing above the normal limitto be expected from the normal rate.29

SummaryThe electrocardiographic and hemodynamic

responses to graded exercise in 11 patientswith congenital complete atrioventricularblock are described. Ventricular rate increasesduring exercise were unrelated to the restingrate, atrial rate, or heart size. Changes in the


ratio of atrial :ventricular rates were observedin all eases during physical work. Physicalworking capacity was normal or only slightlyreduced in all instances. This is accomplishedthrough maintenance of normal minute vol-umes, whieh in turn reflects an interplay ofseveral factors: aeceleration of ventrieularrate, increased heart volume and stroke vol-ume, and a normal or supernormal oxygen-transporting capacity of the blood as reflectedin increased amount of total hemoglobin.

Summario in InterlinguaEs describite le responsas electrocardiographic e

hemodynamic constatate post graduate exercitio in 11patientes con congenite complete bloco atrioventricu-lar. Le augmentos del proratas ventricular durantele exercitio revelava nulle correlation con le proratasin reposo, le proratas atrial, o le dimensiones delcorde. Alterationes in le proportion inter le proratasatrial e ventricular esseva observate in omne le casosdurante le effortio physic. Le capacitate de effortiophysic esseva normal o levemente reducite in omne lecasos. Isto es le resultato del mantenentia de un nor-mal volumine per minuta, un phenomeno que, de suparte, reflecte un concerto de plure factores, i.e. leacceleration del prorata ventricular, le augmento delvolumine cardiac e del volumine per pulso, e un ca-pacitate normal o supernormal de transporto de oxy-geno in le sanguine con le resultato de un augmentodel quantitate total de hemoglobina.

References1. LILJESTRAND, G., AND ZANDEP., E.: Studies of the

work of the heart during rest and muscularactivity in a case of uncomplicated total heartblock. Acta med. scandinav. 66: 501, 1927.

2. ELLIs, L. B., AND WEISS, S.: Studies in completeheart block. The cardiac output and the pe-

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ripheral circulatory mechanism. Am. J. M. Sc.182: 194, 1931.

3. GILCHRIST, A. R.: The effects of bodily rest,muscular activity and induced pyrexia on theventricular rate in complete heart block. Quart.J. Med. 3: 387, 1934.

4. STEWART, H. J.: Studies of the circulation in thepresence of abnormal cardiac rhythms asso-ciated with rapid ventricular rate and torhythms associated with slow ventricular rate.J. Clin. Invest. 17: 449, 1938.

5. KARNI, H., AND WERK6, L.: Total A-V-block.Analys av 24 fall. Nord. Med. 48: 930, 1952.

6. ALTSCHULE, M. D.: Physiology in Diseases of theHeart and Lungs. Cambridge, Mass., HarvardUniversity Press, 1954.

7. LEVINSON, D. C., GUNTHER, L., MEEHAN, J. P.,GRIFFITH, G. G., AND SPRITZLER, R. J.: Hemo-dynamic studies in five patients with heartblock and slow ventricular rate. Circulation12: 739, 1955.

8. CAMPBELL, M., AND THORNE, M. G.: Congenitalheart block. Brit. Heart J. 1: 90, 1955.

9. PAUL, M. H., RUDOLPH, A. M., ONGLEY, P. A.,AND NADAS, A. S.: Congenital complete atrio-ventricular block: a hemodynamic and clinicalstudy. Circulation 14: 987, 1956.

10. DONOSO, E., BRAUNWALD, E., FICK, S., AND

GRISHMAN, A.: Congenital heart block. Am.J. Med. 20: 869, 1956.

11. STACK, M. F., RADER, B., SOBOL, B. J., FARBER,S. J., AND EICHNA, L. W.: Cardiovascularhemodynamic functions in complete heart blockand the effect of isopropylnorepinephrine.Circulation 17: 526, 1958.

12. PAUL, M. H., RUDOLPH, A. M., AND NADAS, A. S.:Congenital complete atrioventricular block:problems of clinical assessment. Circulation18: 183, 1958.

13. GILCHRIST, A. R.: Clinical aspects of high-gradeheart block. Scottish M. J. 3: 53, 1958.

14. HOLMGREN, A., KARLBERG, P., AND PERNOW, B.:Circulatory adaptation at rest and duringmuscular work in patients with complete heartblock. Acta med. scandinav. 164: 119, 1959.

15. FiSH, C.: Complete heart block. New England J.Med. 238: 589, 1948.

16. SJOSTRAND, T.: Changes in the respiratory organs

of workmen. Acta med. scandinav., Suppl. 196:687, 1947.

17. WAHLUND, H.: Determiniation of the physicalwvorking capacity. Acta med. scandinav., Suppl.215, 1948.

18. KJELLBERG, S. R., RUDHE, U., AND SJ6STRAND,T.: The relation of cardiac volume to theweight and surface area of the body, theblood volume and the physical capacity of work.Acta radiol. 31: 115, 1949.

19. LARSSON, H., AND KJELLBERG, S. R.: Roentgen-ologic heart volume determination with specialregard to pulse rate and the position of thebody. Acta radiol. 29: 159, 1948.

20. -MAUREA, C., NYLIN, G., AND SOLLBERGER, A.:Normal heart volume. Acta cardiol. 10: 336,1955.

21. BENGTSSON, E.: The working capacity in normalchildren evaluated by submaximal exercise onthe bicycle ergometer and compared withadults. Acta med. scandinav. 154: 91, 1956.

22. SJOSTRAND, T.: Method for determination oftotal hemoglobin content of the body. Actaphysiol. scandinav. 16: 211, 1948.

23. CARLSTEN, A., HOLMGREN, A., LINROTH, K.,SJdSTRAND, T., AND STROM, G.: Relationshipbetween low values of alveolar carbon monoxideconcentration and carboxyhemoglobin percent-age in the blood. Acta physiol. scandinav. 31:62, 1954.

94. KJELLBERG, S. R., MANNHEIMER, E., RUDHE, U.,AND JONSSON, B.: Diagnosis of CongenitalHeart Disease. Chicago, Year Book Publishers,Inc., 1955.

25. BRINKMAN, R., AND ZIJLSTRA, W. G.: Determina-tion and continuous registration of the per-

centage oxygen saturation in clinical conditions.Arch. chir. neerl. 1: 177, 1949.

26. CAMPBELL, M.: Congenital complete heart block.Brit. Heart J. 5: 15, 1943.

27. STARZL, T. E., GAERTNER, R. A., AND BAKER,R. R.: Acute complete heart block in dogs.Circulation 12: 82, 1955.

28. -, -: Chronic heart block in dogs. A methodfor producing experimental heart failure.Circulation 12: 259, 1955.

29. HOLMGREN, A., JONssON, B., LEVANDER, M.,LINDERHOLM, H., SJdSTRAND, T., AND STROM,G.: Low physical working capacity insuspected heart cases due to inadequate adjust-ment of peripheral blood flow (Vasoregulatoryasthenia) Acta med. scandinav. 158: 413, 1957.


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Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1960 American Heart Association, Inc. All rights reserved.

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