British Heart Journal, 1979, 41, 683-691

Maximal supine exercise haemodynamics after openheart surgery for Fallot's tetralogyGORDON R. CUMMING

From the Department of Pediatrics, Health Sciences Children's Centre and The University of Manitoba,Winnipeg, Manitoba, Canada

SUMMARY Maximal supine exercise studies at the time of heart catheterisation were performed one tofive years after open heart surgery for Fallot's tetralogy on 29 subjects 6 to 16 years of age. Duringexercise right ventricular systolic pressure exceeded 50 nmmHg in all but 2 subjects, and end-diastolicpressure increased to over 15 mmHg in 10 subjects. Pulmonary artery peak systolic pressure was ab-normal in 5 patients. Maximal exercise cardiac index was below the normal range in only 2 subjects,but below the mean for normals in 80 per cent of the patients. Only 3 patients had clinical exerciseperformances below the 3rd centile of normal subjects using a maximal upright bicycle exercise test,and only 1 subject was below the normal range for endurance time on the Bruce treadmill test. Thepatients in this series performed better than those in other series, possibly because of their younger ageat operation, the use of a large control series of normal subjects taken from a clinic population, thewillingness of the patients to work to near exhaustion, and previous encouragement of the patients tobecome normally active children.

There are several published reports of haemody-namic studies after open heart surgery in patientswith Fallot's tetralogy, and some of these includeexercise data (Gotsman, 1966; Shah and Kidd,1966; Bristow et al., 1970; Epstein et al., 1973;Bjarke, 1975; Mocellin et al., 1975, 1976). Thefollowing report differs from these others in one ormore ways: studies were made during exercise ona large number of subjects including those withand without various residual defects; measurementswere made during maximal exercise; haemody-namic measurements included intracardiac pres-sures, arterial and mixed venous blood gas tensions,and cardiac output (by indicator dilution method),during submaximal and maximal exercise in thesupine position. Clinical exercise testing used bothmaximal treadmill and bicycle exercise. The sub-jects were younger than those in other series andcomparative data were available for a large seriesof normal children studied in the same manner.

Subjects

The patients studied were 29 children who had hadopen heart operations at ages ranging from 5 to14 years (mean 8&2). All but 2 were cyanotic at thetime of operation. Of the 29 (34%), 10 had had a

Received for publication 20 February 1978

previous shunt operation. An outflow tract patchhad been inserted in 11 of the 29 patients (38%),and in 7 this extended to the pulmonary arterybifurcation. The catheterisation studies werecarried out 1 to 5 years after operation (mean age11-3 years, range 6 to 16). The exercise studies wereperformed at the time of diagnostic postoperativehaemodynamic assessment.The patients were divided into 5 subgroups:

(1) those in the 'repaired' group with a closedventricular septal defect and a peak gradient fromright ventricle to pulmonary artery of 20 mmHg orless (11 patients); (2) those with a closed ventricularseptal defect but a peak gradient of over 20 mmHg(7 patients); (3)thosewith a small residual ventricularseptal defect and pulmonary blood flow 1-25 timessystemic flow or less (4 patients); (4) those with a'poor repair' with a large ventricular septal defectand also an outflow gradient of over 20 mmHg(5 patients); and (5) 2 patients with completeatrioventricular block, both with a permanentpacemaker set at 80 beats/minute, but otherwise agood surgical result.

Methods

The haemodynamic studies were carried out afteran overnight fast 45 minutes after diazepam 5 mg

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Gordon R. Cumming

or pethidine 25 mg. Catheters were introducedpercutaneously into a cubital or femoral vein, andthe brachial artery was cannulated with a Cournandneedle. After the exercise studies most subjects alsohad right and left ventriculograms. Control measure-ments were obtained 5 minutes after the subject'sfeet had been placed on and strapped to the ergo-meter pedals. A calibrated Elema electric ergometerwas used with pedalling rates of 60 rpm for sub-maximal exercise and 70 to 75 rpm for maximalexercise. Subjects exercised for 3 minutes at about5 kpm/min per kg body weight, rested 3 minutes,then exercised for 3 minutes at 8 to 12 kpm/minper kg, rested again for 5 to 10 minutes, and thenexercised at 15 to 25 kpm/min per kg until theycould no longer sustain the pedalling rate. Thefinal work load (chosen on the basis of a clinicalexercise test and the response to the previous loads)usually exhausted the subjects in 90 to 180 seconds.Oxygen uptake was not measured but the sub-maximal loads would have required about 14 and25 ml/min per kg of oxygen, and the maximal loadsif done aerobically 32 to 55 ml/min per kg ofoxygen. Five of the 29 subjects did not exercise ata maximal work load as they were studied beforemaximal exercise testing was used routinely in thecatheterisation laboratory.During exercise pulmonary and brachial artery

pressures were recorded using a Statham P23Dbtransducer, and immediately after the maximalexercise the catheter was withdrawn from thepulmonary artery to the right ventricle. Cardiacoutput was measured using indocyanine green dyeand a Waters densitometer, and a dynamic calibra-tion method (Shinebourne et al., 1967). For thefew patients with significant left-to-right shunts,pulmonary blood flow was calculated from theindicator dilution curves using the forward trianglemethod (Hetzel et al., 1958), the left-to-right shuntwas estimated using the method of Carter et al.(1960), and systemic output was derived from thesetwo measurements. During the third minute at eachexercise level, blood was withdrawn from thepulmonary and brachial arteries for Po2 and pHdeterminations. Percentage oxygen saturation wasderived using the standard oxyhaemoglobin dis-sociation curve.

Clinical exercise testing was carried out on theupright bicycle ergometer and on the treadmill in aclinical laboratory. On the upright bicycle ergometer,the subjects exercised at 5 to 8 kpm/min per kg for6 minutes, and at 9 to 13 kpm/min per kg for 6minutes, after which the work load was increased by100 kpm/min each minute until exhaustion occurred.Maximal work was expressed as kpm/min per kgand compared with centiles for normal children

established for this laboratory (Cumming, 1977a).Subjects also performed the Bruce treadmill testand the maximal work times were compared withcentiles for normal children established for thislaboratory (Cumming et al., 1978). Normal centilevalues for both treadmill and bicycle exercise wereestablished from exercise tests in over 500 childrenwho did not have heart disease and who were seenin a cardiac clinic over a 10-year period.

Results

The haemodynamic results are shown in Fig. 1 to 8,with shaded areas to show the normal range (mean± 2 standard deviations) for 60 children studiedover the same period of time as the tetralogypatients. None of the patients developed anarrhythmia during exercise at catheterisation.Subject 6 subsequently developed exercise inducedventricular tachycardia with treadmill testing, ashas been reported by James et al. (1976) in patientsafter operation for Fallot's tetralogy.The peak right ventricular pressure increased

during exercise in all subjects and in only 3 subjectswas the pressure during exercise less than thenormal maximal value of 48 mmHg (Fig. 1). Thepeak right ventricle to pulmonary artery pressuregradient increased during exercise in all subjects,and in all but 4 subjects was abnormal during exer-cise (Fig. 2). There was one very high value inthe 'poor repair' group, and 5 of 7 subjects withresidual pulmonary stenosis had peak gradients ofover 50 mmHg with exercise. There was a strongcorrelation between the resting and exercise right

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Fig. 1 Peak systolic pressure in the right ventricle atrest (R) and immediately after exercise (E). Normal rangeis shown by hatched columns.

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Maximal supine exercise haemodynamics after open heart surgeryfor Fallot's tetralogy

RFig. 2 Peak right ventricularsystolic pressure minuspeak pul-

E monary artery systolic pressuresat rest (R) and immediately after

P exercise (E). Normal range(up to 8mmHg rest and 20 mmHgafter exercise) is shown.

Repai red Pulmonarystenosis

ventricular systolic pressures and right ventricle topulmonary artery gradient though there were a fewexceptions (2 patients with resting gradients of2 and 32 mmHg had exercise gradients of 40 and94 mmHg, respectively).

Right ventricular end-diastolic pressure increasedabnormally in all 5 subjects in the 'poor repair'group, in both patients with atrioventricular block,and in 3 of the 7 patients with resting gradientsover 20 mmHg (Fig. 3). Several other patients hadan abnormal right ventricular end-diastolic pressureat rest but did not show any major increases on

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exercise. There was a low order correlation betweenthe exercise right ventricular end-diastolic pressureand the right ventricular systolic pressure.

Fig. 4 shows the cardiac output at submaximalwork loads expressed as the increase in outputabove the resting value. Eighty-four per cent of the45 values fell below the mean established for thenormal subjects, but only 6 (13%) were more than 2standard deviations below the mean and these lowvalues occurred in 3 patients. Values above themean for the normals were observed 7 times,though none was more than 1 standard deviation

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Fig. 3 Right ventricularend-diastolic pressure at rest (R)

R and after exercise (E). Normalrange (up to 5 mmHg at rest and8mmHg during or after exercise)is shown.

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Gordon R. Cumming

14

* Complete repair* Poor repairA Small VSD* Gradient .

o AV block .'

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Fig. 4 Cardiac output increase aexercise (A (). Exercise cardiac oloutput in litres per minute plotted 4kilopond metresper minute. Regrefor normal subjects with standard

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Repaired Pulmonary VSD Poor AV blockstenosi s re pai r

Fig. 5 Cardiac index in litres/minute per m' body500 700 900 surface area at rest and during maximal exercise. Hatched

columns indicate the normal ranges which are the samevith submaximal for boys andgirls at rest, but different during exercise:utput minus resting during exercise the normal rangesfor boys are shown onagainst work load in the left, and the normal rangesfor girls on the right; thession (solid) line is shown dotted lines in these ranges indicate the mean valuesfordeviations (dotted lines). the normalgroup.

above the mean. Thus, the cardiac output duringsubmaximal exercise was in the lower half of thenormal range in most patients.

Resting cardiac index was below 2-9 1/min perm2 in 5 subjects (21%) and below the mean of thenormal values for this laboratory in 18 subjects(75%) (Fig. 5). Maximal exercise cardiac index(measured in 24 patients) was below the normalrange in two subjects, the boy with completeatrioventricular block and one patient with a poorrepair. However, maximal cardiac index was below

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the mean value for normals in 19 of the 24 subjectsexercised maximally (79%).During submaximal supine exercise, stroke

volume in normal children usually increases about10 per cent above resting (Cumming, 1972). Theresponse to maximal exercise is variable, withstroke volume either staying the same, decreasing,or occasionally increasing slightly compared withvalues for submaximal exercise. Fig. 6 shows theresting stroke volume indices, and the highest valuesobserved during exercise. There was an increase in

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Fig. 6 Stroke volume index inml/beat per m2 body surface areaat rest (R) and during exercise (E).The normal ranges are shown as inFig. 5.

VSD Poor repair AV block

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Maximal supine exercise haemodynamics after open heart surgery for Fallot's tetralogy

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Fig. 7 Percentage oxygen saturation in ptblood durine exercise plotted a'ainst work 1l

values below the normal range, including the 2o patients in group 5 with heart block. Some of the* patients with left-to-right shunts had values in theA high normal range.LO The arterial Po2 values during the maximal

exercise performed by each subject are shown inFig. 8. Relatively low Po2 values were found in somenormal subjects during near maximal supineexercise, the lower limit of normal being 75 mmHg.(When blood is collected 2 or 3 minutes afterexercise, most normal subjects, including thosewith exercise values of 75 to 80 mmHg, havearterial Po2 values in the range of 90 to 110 mmHg.)In the postoperative Fallot's tetralogy patientsarterial Po2 was below the normal range in 14 of the28 patients. In 1 subject this was associated with amoderate right-to-left shunt on the indicatordilution curve, but in the other patients no right-to-

0 left shunt was present. In view of the interestingabnormalities in lung function that follow systemic-to-pulmonary shunt operations (Alderson et al.,

20 2: 1975), those patients who had had previous shuntoperations are indicated in Fig. 8, but their values

ulmonary artery were no lower than those without previousnoad inkmImin shunt operations.-- -5t -#-gS-r wC>b f-.1 - t- w1.- r*lf

per kg body weight. Hatched area shows normal range.

stroke volume index with exercise in all except 2patients. This increase was greatest in the 2 subjectswith heart block.The percentage oxygen saturation in the pul-

monary artery blood during exercise is plottedagainst the work load per kg body weight in Fig. 7.There were some subjects in all patient groups with

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Fig. 8 Brachial artery Po2 during the maximal supineexercise loadperformed by the subjects. Shaded area showsthe normnal range in this laboratory. Patients who hadprevious systemic-to-pulmonary artery anastomoses are

shown by M. Patient * was the only one with a right-to-left shunt on the indicator dilution curve.

0 Repaired A Poor repair* PS 0 AV blockA VSD

Fig. 9 Exercise capacity on treadmill (endurance time)and upright (maximal work load) bicycle ergometer.Normal centile values were obtained on clinic patientswith innocent heart murmurs.

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Gordon R. Cumming

The endurance times with the Bruce treadmillprocedure and the maximal exercise load with theclinical bicycle ergometer test are shown as centilesof the values established for children without heartdisease in Fig. 9. For treadmill exercise the meancentile recorded by the postoperative Fallot'stetralogy patients was 45 per cent, excluding the 1patient who developed ventricular tachycardia withexercise. Of the 25 subjects tested, 52 per cent hadvalues below the 50th centile, 16 per cent had valuesapproximately on the 50th centile line, and 32 percent had values above the 50th centile line. The meanmaximal heart rate was 189 beats/min (normalmean 202 beats/min).The maximal work loads completed on the

upright bicycle ergometer were above the 50thcentile line in 7 subjects (24%), below the 25thcentile line in 9 (31%), including 3 (10%) belowthe 3rd centile line, and no subject had a valueabove the 75th centile line. The mean centile scorewas 37 per cent. Mean group centile exercisecapacities were lowest in the patients with atrio-ventricular block and in those with a 'poor repair',but there was considerable overlap. The meanmaximal exercise heart rate was 183 beats/min(normal mean 196 beats/min).

Discussion

The systolic pressure increase on withdrawing thecatheter from the pulmonary artery to the rightventricle was abrupt and no intermediate zonesuggestive of infundibular stenosis was observed.This was in keeping with the right ventricularangiograms which showed wide open outflow tractsin all patients. The pressure changes appeared to beoccurring in the area of the pulmonary valve ring,or at the bifurcation of the main pulmonary artery,and while these were the narrowest areas on theangiograms a significant gradient would not havebeen suspected from viewing the angiograms.The rise in exercise right ventricular end-

diastolic pressures is in agreement with the reportof Bristow et al. (1970) and might be the result ofthe previous right ventricular incision, the pul-monary regurgitation, the increase in right ventri-cular systolic work, or of myocardial hypertrophyand scarring with reduced compliance. The highestend-diastolic pressures were found in the subjectswith the most severe haemodynamic disturbances,but the right ventricular end-diastolic pressures didnot correlate with exercise cardiac output or theclinical exercise capacity, or the presence of apulmonary regurgitant murmur.

Peak systolic pulmonary artery pressures might beabnormally high on the basis of branch narrowings,

reduced size or compliance of the major pulmonaryarteries, inadequacy of the pulmonary vascular bed,possible old thrombotic occlusions, or increasedright ventricular stroke volume because of thepulmonary regurgitation, or combinations of theabove causes. At preoperative catheterisation, noneof the patients had pulmonary hypertension fromprevious shunt procedures. There was no corre-lation between the peak pulmonary artery pressureand the clinical grading of the pulmonary regurgita-tion murmur or the presence of a systemic-to-pulmonary shunt.The submaximal and maximal exercise cardiac

indices and stroke volume indices were clusteredin the lower part of the normal range. This is abetter response than those reported by Epstein et al.(1973) and by Bjarke (1975). The submaximalexercise cardiac outputs were in the lower part ofthe normal range because of low stroke volumes.The maximal cardiac outputs were low because oflow maxImal heart rates. The mean maximalexercise heart rate for the supine exercise at thetime of catheterisation was only 164 beats/min,and this low figure is believed to be due to threefactors. Maximal exercise heart rates in the supineposition are normally 10 beats/min below those forthe sitting position in adults and in children(Astrand and Saltin, 1961; Stenberg et al., 1967;Cumming, 1977b). Secondly, maximal exercise heartrates for upright bicycle and treadmill exercise havebeen reported to be reduced by 20 beats/min inpost-surgical patients with Fallot's tetralogy (Ep-stein et al., 1973; Bjarke, 1975), though the causeis uncertain. Thirdly, the short duration of themaximal exercise used in this study would be anadditional factor reducing the maximal heart rate.At catheterisation the duration of the exercise waspurposely kept short as this has been one way ofobtaining the co-operation of young children. Thesubjects pedalled until they could not maintain thecycling speed of 70 rpm, and most appeared to havegiven a true near maximal effort; the only way theduration of exercise could have been increasedwould have been to reduce the work load used.A slight fall in arterial oxygen saturation with

exercise in postoperative tetralogy patients wasreported by Epstein et al. (1973) and in the studyof Bjarke (1975) PaO2 fell from 99 to 85 mmHgwith upright bicycle exercise. The lower values inthe patients in this series may have been caused inpart by the supine position and the straining thatthis type of exercise produces. Ventilation perfusionabnormalities have been well documented in post-operative tetralogy patients (Alderson et al., 1975).

Before any reduction in maximal exerciseperformances of post-surgical patients can be

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Maximal supine exercise haemodynamics after open heart surgeryfor Fallot's tetralogy

attributed to residual lesions and impaired cardiacfunction, it is important to exclude non-cardiacfactors. Have the patients actually resumed fullactivity for at least 6 months or longer, or have theyheld back for one reason or another ? Are thepatients really being urged to produce maximalefforts in the tests ? Is the normal group of subjectsroughly comparable with the patients in terms ofcurrent physical activity ? When comparing theexercise haemodynamic indices or exercise capacitymeasurements in patients with values in normalsubjects, it is important that both groups shouldhave engaged in comparable physical activity.Ideally, both groups should undergo a similarphysical training programme 3 or 4 months beforea study, and this would include practice sessionswith all test procedures. As this was not feasible,the normal values in this study were obtained froma large series of patients who proved to have normalhearts, or nearly normal hearts, when undergoingcardiac evaluation over the same period of time asthe postoperative tetralogy patients. The tetralogypatients in this series were all urged gradually toresume normal activities, including full participationin physical education 6 months after operation. Theparents were advised to encourage their children toparticipate normally in all activities while allowingthem to seek their own levels of participation ratherthan to be coached and pushed. Several children,in fact, did take part in demanding sports such asice-hockey or soccer, but none trained seriouslyfor competitive athletics.The results of all maximal exercise tests are

dependent on motivating the patients to work closeto exhaustion, and the skill and determination ofexercise technicians is an important factor. All ofthe subjects in this report finished at least stage 4of the Bruce test which, if done aerobically, requiresan oxygen uptake of 46 ml/min per kg (Cumminget al., 1978). While oxygen uptake was not directlymeasured, there is no reason to believe that thework efficiency or the anaerobic power of thesepatients was any greater than in normal subjects.The patients in this series clearly had higher

functional capacities than those in the series ofEpstein et al. (1973) and Bjarke (1975) (Vo2 max25 to 30 ml/min per kg) possibly because the opera-tion was performed at a younger age and the patientshad the motivation and opportunity to becomenormally active. The younger patients of Mocellinet a!. (1975) also had cardiac output values closerto normal than those reported by Epstein et al.(1973) and Bjarke (1975). It is of interest that withclinical exercise testing our patients were able topush themselves to a mean maximal heart rate of189 beats/min compared with approximately 175

beats/min in the studies of Epstein et al. (1973) andBjarke (1975), and 182 beats/min in the study ofJames et al. (1976). Maximal heart rates of over190 beats/min, well within the range of normalfor maximal heart rate, were recorded duringclinical exercise testing in 15 of the 27 patients (2patients with atrioventricular block omitted). Itwould be of value to study systematically the re-sponse of postoperative tetralogy patients to physi-cal training regimens, but the results reportedhere indicate that formal rehabilitation programmesare not necessary for these patients to achieve areasonable functional status.

James et al. (1976) found that patients operatedon at an earlier age (under age 10) had exercisecapacities not significantly different from normalsubjects, while those operated on at an older agehad subnormal exercise capacities when tested byclinic bicycle ergometry, in agreement with thefindings of this report. They also studied 4 oldersubjects who took part in competitive sports, andfound that their exercise capacities were also normal,suggesting that the potential for a normal exercisecapacity is present if physical activity is encouragedfor these patients.The mean age of the 10 patients studied by

Epstein et a!. (1973) was 23 years, and of the 18patients studied by Bjarke (1975) 20 years atoperation and 26 years at the time of the post-operative exercise study. The cardiac output res-ponse to treadmill exercise in Epstein's series wasonly slightly below normal, but there was anabnormally low cardiac index at the point whenpulmonary artery oxygen saturation fell to 30 percent. In the study of Bjarke (1975), cardiac outputsduring upright bicycle exercise were clustered inthe low normal range and 50 per cent of the subjectshad values below the normal range in relation tooxygen uptake. In their patients the circulationtended to be hypodynamic in tetralogy patientsafter operation, even when allowance was made forthe reduced maximal exercise capacity and maximaloxygen uptake. In the patients in our series studiedduring supine exercise, the changes were similarin direction but not in magnitude, so that theexercise cardiac outputs were at the lower end ofthe normal range but not below. The study ofMocellin et al. (1976) involved 21 children, meanage 12 years, operated on at a mean age of 8-5 years,subjects comparable to those in the present report.Mean maximal exercise heart rate was 196 beats/min, the same as normals. The mean maximal V02,stroke volume, and cardiac output were 83 to 89per cent of mean normal values (based on height),though information was not provided on the normalrange or the method of selection of the normal

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Gordon R. Cumming

subjects. Presenting our patients' data in the sameway and omitting those with a poor repair oratrioventricular block, the mean values for exercisecapacity, stroke volume, and cardiac output werealso 85 to 90 per cent of the means for normals.The mean Vo2 max in Mocellin's subjects wasdetermined directly on the bicycle ergometer andwas 37 and 34 ml/min per kg for boys and girls,respectively, lower than the predicted values basedon treadmill performance in our patients. Mocellinet al. indicated that only half of their children tookpart in school sports, but it is not known whetherintense physical activity might be damaging tothese children or the only way in which they mightachieve a normal functional capacity. All theevidence available suggests that early operation maypermit the development of a more normal exerciseperformance. This may be entirely because of theresumption of normal physical activity during theyears of development, but there is also the possibilitythat cardiac fibrosis, a small left ventricle, and otheranatomical abnormalities occur to a greater degreewhen surgical correction is delayed until lateadolescence or adulthood.

Conclusions

(1) After corrective operations for tetralogy ofFallot there are residual haemodynamic abnormali-ties during exercise, the most striking being highright ventricular systolic and end-diastolic pressures.The high right ventricular systolic pressure occursin the absence of any angiographic evidence ofoutflow tract obstruction.(2) When the corrective operation was done inchildhood (age 5 to 13 years), patients with Fallot'stetralogy had exercise capacities in the low normalrange during treadmill, upright bicycle, or supinebicycle exercise.(3) After corrective operations in childhood, themaximal and submaximal exercise cardiac outputsand stroke volumes fall in the lower part of thenormal range, but are usually not below normal.The hypodynamic circulation is partially compen-sated for by a wider arteriovenous oxygendifference.(4) Patients with a poor repair or with atrioventri-cular block (with pacemakers) had only slightlyless good exercise performances and cardiac outputmeasurements than those with better anatomicalresults.

All but one of the patients in thisoperated on by Dr Colin C.Department of Surgery, Children'sWinnipeg.

series wereFerguson,

Hospital of

References

Alderson, P. O., Boonvisut, S., McKnight, R. C., andHartman, A. F., jun (1975). Pulmonary perfusion ab-normalities and ventilation perfusion imbalance in childrenafter total repair of tetralogy of Fallot. Circulation, 53,332-337.

Astrand, P. O., and Saltin, B. (1961). Maximal oxygen uptakeand heart rate in various types of muscular activity.Journal of Applied Physiology, 16, 977-981.

Bjarke, B. (1975). Oxygen uptake and cardiac output duringsubmaximal and maximal exercise in adult subjects withtotally corrected tetralogy of Fallot. Acta Medica Scandi-navica, 197, 177-186.

Bristow, J. D., Kloster, F. E., Lees, M. H., Menashe, V. D.,Griswold, H. E., and Starr, A. (1970). Serial cardiaccatheterisations and exercise hemodynamics after correctionof tetralogy of Fallot. Circulation, 41, 1057-1066.

Carter, S. A., Bajec, D. F., Yannicelli, E., and Wood, E. H.(1960). Estimation of left to right shunts from arterialdilution curves. J'ournal of Laboratory and Clinical Medicine,55, 77-88.

Cumming, G. R. (1972). Stroke volume during recovery fromsupine bicycle exercise. Journal of Applied Physiology, 32,575-578.

Cumming, G. R. (1977a). Exercise studies in clinicalpediatric cardiology (Proceedings of the VIIth InternationalSymposium of Pediatric Work Physiology). In Frontiers ofActivity and Child Health, pp. 17-45, ed H. Lavallee andR. Shephard. editions du Pelican, Ottawa.

Cumming, G. R. (1977b). Hemodynamics of supine bicycleexercise in 'normal' children. American Heart Journal, 93,617-622.

Cumming, G. R. Comparison of maximal supine andupright bicycle exercise in children. In preparation.

Cumming, G. B., Everatt, D., and Hastman, L. (1978).The Bruce treadmill test in children: normal values in aclinic population. American Journal of Cardiology, 41,69-75.

Epstein, S., Beiser, D., Goldstein, R., Rosing, D., Redwood,D., and Morrow, A. (1973). Hemodynamic abnormalitiesin response to mild and intense upright exercise followingoperative correction of an atrial septal defect or tetralogyof Fallot. Circulation, 47, 1065-1075.

Gotsman, M. S. (1966). Hemodynamic and cine-angiographicfindings after one stage repair of Fallot's tetralogy. BritishHeart_Journal, 28, 448-460.

Hetzel, P. S., Swan, H. J. C., Ramirez de Arellano, A. A.,and Wood, E. H. (1958). Estimation of cardiac output fromthe first part of arterial dye dilution curves. Yournal ofApplied Physiology, 13, 92-96.

James, F. W., Kaplan, S., Schwartz, D. C., Chou, T.,Sandker, M. J., and Naylor, V. (1976). Response to exercisein patients after total surgical correction of tetralogy ofFallot. Circulation, 54, 671-679.

Mocellin, R., Bastanier, C., Hofacker, H., and Biuhlmeyer, K.(1975). Klinische und funktionelle Ergebinisse bei kindernmit Fallotscher Tetralogie nach Korrekturoperation.Monatsschrift fur Kinderheilkunde, 123, 363-365.

Mocellin, R., Bastanier, C., Hofacker, W., and Buhlmeyer, K.(1976). Exercise performance in children and adolescentsafter surgical repair of tetralogy of Fallot. European J7ournalofCardiology, 4, 367-374.

Shah, P. L., and Kidd, L. (1966). Hemodynamic responses to

exercise and to isoproterenol following total correction ofFallot's tetralogy. Journal of Thoracic and CardiovascularSurgery, 52, 138-145.

Shinebourne, E., Fleming, J., and Hamer, J. (1967). Calibra-tion of indicator dilution curves in man by the dynamic

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Maximal supine exercise haemodynamics after open heart surgery for Fallot's tetralogy 691

method. British Heart_Journal, 29, 920-925. Requests for reprints to Dr Gordon R. Cumming,Stenberg, J., Astrand, P. O., Ekblom, B., Royce, J., and Section of Cardiology, Health Sciences Children's

Saltin, B. (1967). Hemodynamic response to work withdifferent muscle groups sitting and supine. Yournal ofApplied Centre, 685 Bannatyne Avenue, Winnipeg, Mani-Physiology, 22, 61-70. toba, Canada R3E OWL.

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surgery for Fallot's tetralogy.haemodynamics after open heart Maximal supine exercise

G R Cumming

doi: 10.1136/hrt.41.6.6831979 41: 683-691 Br Heart J 

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