PEDIATRICS Vol. 118 No. 3 September 2006, pp. e586-e593 (doi:10.1542/10.1542/peds.2006-0264)
ARTICLE |
Sustained Effects of Cardiac Rehabilitation in Children With Serious Congenital Heart Disease
Department of Pediatric Cardiology, Children's Hospital, Boston, Massachusetts
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONREFERENCES |
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OBJECTIVE. Past studies have documented the acute benefits of cardiac rehabilitation in children with congenital heart disease. It is not known whether these benefits persist.
PATIENTS AND METHODS. Fifteen patients, ages 8 to 17 years, with complex congenital heart disease, whose exercise function immediately after a 12-week cardiac rehabilitation program was superior to that present on a precardiac rehabilitation exercise test, were restudied 6.9 ± 1.6 months after completion of the cardiac rehabilitation program (
1 year after the precardiac rehabilitation study). Changes in exercise function relative to baseline, precardiac rehabilitation exercise tests were also compared with changes observed in a group of 18 control subjects, with similar diagnoses, who also had 2 exercise tests separated by a year but did not undergo cardiac rehabilitation.
RESULTS. The cardiac rehabilitation patients' exercise function did not change significantly over the 6.9-month period after the completion of the cardiac rehabilitation program; percentage of predicted peak oxygen consumption and peak work rate remained significantly superior to baseline, precardiac rehabilitation values. These changes were also associated with improvements in self-esteem, behavior, and emotional state. In contrast, among the control subjects, small, but statistically insignificant declines in peak oxygen consumption and peak work rate were observed on the final exercise test compared with values obtained at baseline, 1 year earlier. The improvements realized by the cardiac rehabilitation patients differed significantly from the concurrent changes observed among the control subjects and appeared to be a result of an increase in the oxygen pulse at peak exercise; significant changes in peak heart rate were not observed.
CONCLUSIONS. In patients with congenital heart disease, cardiac rehabilitation produces significant, sustained improvements in exercise function, behavior, self-esteem, and emotional state.
Key Words: exercise testing • congenital heart disease • rehabilitation • exercise
Abbreviations: 
O2—oxygen consumption • VAT—ventilatory anaerobic threshold • CHQ—child health questionnaire • RER—respiratory exchange ratio • VE—minute ventilation • MVV—maximum voluntary ventilation
Past studies have evaluated the acute effects of cardiac rehabilitation in children with congenital heart disease.1–11 Although the results of these studies have been mixed, the majority have found that cardiac rehabilitation produces an acute improvement in exercise capacity. However, few of these studies have been well controlled, and none have explored whether the acute improvement is sustained beyond the immediate postrehabilitation period.
We reported recently the acute effects of a cardiac rehabilitation program in 16 patients with serious congenital heart disease.9 On exercise tests performed at the end of a 12-week rehabilitation program, we found that the peak oxygen consumption (O2) and/or peak work rate improved compared with prerehabilitation tests in 15 of the 16 patients. The purpose of the current study was to determine whether the improvements realized by these 15 patients were sustained, and whether the changes in exercise function observed in the rehabilitation patients were superior to those of a control group, with similar diagnoses and disabilities, who did not participate in a rehabilitation program.
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METHODS |
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Patient Recruitment
This study was limited to patients with serious congenital heart disease. The rehabilitation subjects were recruited from patients 8 to 18 years of age who were referred for exercise tests at the Children's Hospital exercise physiology laboratory within the 6 months before the initiation of the rehabilitation program. All of the subjects had
1 open-heart surgery or interventional catheterization procedure during infancy or early childhood. To qualify for the rehabilitation program, the subjects also had to have a peak work rate and/or peak O2 <80% of predicted and a commitment to attend and participate in rehabilitation sessions. For safety purposes, patients with medical conditions and/or exercise test abnormalities that could pose a health risk during exercise were excluded from the study.9
The control group was also recruited from patients referred for exercise tests at the Children's Hospital exercise physiology laboratory. These patients met enrollment criteria identical to those of the rehabilitation patients. They were, however, unable to participate in the rehabilitation program because of geographic or other social constraints. Both rehabilitation and control patients were 6 months status post their last surgical or interventional catheterization procedure, and no patient had an additional procedure during the course of the study.
Rehabilitation Program
Details of the rehabilitation program have been described previously.9 Briefly, the subjects met for 1-hour sessions twice a week for 12 weeks. The subjects were divided by age into 2 groups (8- to 13-year-olds and 13- to 17-year-olds). Each session began with 5 to 10 minutes of stretching exercises followed by 45 minutes of aerobic and light weight/resistance exercises. The subjects were encouraged to exercise at an intensity sufficient to raise their heart rates to levels equal to that associated with the ventilatory anaerobic threshold ([VAT] as determined on their baseline exercise tests). The last 5 to 10 minutes of each session were devoted to cooling down and stretching. Games, rubber balls, music, and simple, age-appropriate prizes (eg, baseball cards) were incorporated into the activities to promote enthusiasm and motivation. Attempts were also made to vary activities and to accommodate the moment-to-moment desires of the subjects to optimize participation and interest. Subjects were also encouraged to exercise at home on 2 additional occasions per week. This message was reinforced at each rehabilitation session, but a specific home exercise program was not prescribed, and compliance was not monitored.
Exercise Testing
Exercise testing was performed using a progressive, symptom-limited bicycle ergometry protocol according to the methods of Wasserman et al.12 Electrocardiographic monitoring and breath-by-breath expiratory gas analysis were performed with a Medical Graphics exercise testing system (Medical Graphics Corp, St Paul, MN). As stated previously, all of the rehabilitation and control subjects performed a baseline exercise test within the 6 months before the initiation of the rehabilitation program. All of he rehabilitation subjects performed another exercise test within 2 weeks of the end of the rehabilitation program. All of the rehabilitation and control subjects also performed a final exercise test 1 year after the initial, prerehabilitation program exercise test (4–9 months after the completion of the rehabilitation program). Spirometric measurements were also performed at the time of each exercise test. A $50 monetary award was issued to each subject at the follow-up exercise test. Calculations and predicted values were obtained as described previously.9
Health Status Assessment
All of the rehabilitation and control subjects completed the Child Health Questionnaire (CHQ) Child Form-87, an 87-item instrument that provides a profile of 10 individual health concepts. They also completed an 8-item supplemental questionnaire regarding the nature and frequency of their exercise activities and limitations. In addition, the subjects' parents completed the CHQ Parent Form-50, a comprehensive, 50-item instrument developed and validated by the Health Institute at New England Medical Center (Boston, MA) for the evaluation of health status in children 5 to 18 years of age. It has 12 individual concepts (including socioeconomic data) and 2 summary scores (physical and psychosocial).13 The questionnaires were completed at 2 time points: at baseline and at the time of the final exercise test, 1 year after the baseline studies.
This study was approved by the Committee on Clinical Investigation at Children's Hospital. All of the parents signed consent forms, and all of the children gave their assent before enrolling in the study.
Statistical Analysis
All of the continuous variables were summarized as mean ± SD. A Student's unpaired t test was used to compare data between groups of rehabilitation and control subjects. A Student's paired t test was used to compare data from the same subject at the different time points (ie, baseline, postrehabilitation, and final for the rehabilitation group and baseline and final for the control group). Univariate regression analysis was used to assess the relationship between continuous variables. For CHQ individual concepts and summary scores, changes in scores from baseline to final follow-up were compared for subjects and controls using Student's unpaired t test. Because items on the supplemental questionnaire were measured on an ordinal scale, comparisons were made using the Wilcoxon rank sum test. Because the subjects grew significantly during the 1 year that separated the initial and final exercise tests, and because many of the subjects were undergoing changes in stature and body habitus associated with puberty, the analyses of the effect of cardiac rehabilitation on exercise performance focused primarily on percentage of predicted values, rather than the absolute magnitude or weight-normalized values, of the various parameters of exercise performance, that is, the peak O2, peak work rate, oxygen pulse at peak exercise, and O2 at the VAT.
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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Preservation of Exercise Function After Completion of the Rehabilitation Program
The exercise function of the 15 rehabilitation patients was well preserved after the 6.9 ± 1.6 months that elapsed between the immediate postrehabilitation exercise test and the final exercise test (undertaken
1 year after the baseline, prerehabilitation exercise tests). During this time period, peak work rate and peak O2 increased (Fig 1) in proportion to the patients' somatic growth. Consequently, significant changes in percentage of predicted peak O2, in percentage of predicted peak work rate, and in the VAT (expressed as the percentage of predicted peak O2) were not observed (Table 1). Peak-exercise heart rate and respiratory exchange ratio ([RER] the ratio of carbon dioxide production over O2; the magnitude of the peak RER roughly reflects the effort expended by the subject at peak exercise14) were unchanged.
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) and the control subjects (•). The final exercise test was performed
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Comparison of Rehabilitation Patients and Control Subjects
At the time of their initial exercise tests, the rehabilitation and control groups did not differ with regard to age, height, weight, or body mass index. They also carried similar cardiac diagnoses. Eleven of the 15 rehabilitation patients and 14 of the 18 control subjects had had Fontan procedures. The average number of surgical procedures per patient and the average number of cardiac medications per patient were also similar (Table 2). Statistically significant differences did not exist between the rehabilitation and control groups' questionnaire responses. Of note, 53% of the rehabilitation patients and 56% of the control subjects perceived that their parents limited their physical activities; 53% of the rehabilitation patients and 50% of the control subjects perceived that their doctors limited their physical activities, on account of concern about their heart problems. The groups' socioeconomic data were also similar.
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The exercise function of the 2 groups was also quite similar (Table 2). The rehabilitation and control subjects did not differ with regard to any of the baseline exercise test or spirometric parameters examined. In both groups, the
O2 and work rate at peak exercise were reduced to 60% to 65% of predicted values, and the O2 at the VAT was abnormally low. In neither group were the patients able to increase their heart rate or oxygen pulse to appropriate levels at peak exercise. Both groups achieved peak-exercise RER in excess of 1.10 (indicating that the subjects expended good efforts).
At the final exercise test, the rehabilitation subjects' percentage of predicted peak O2 was 11.2 ± 12.1 percentage points higher than it had been on the baseline exercise test 1 year earlier (P < .01; Table 3). Peak O2 improved in 12 subjects, was unchanged in 1, and declined in 2 (Fig 2A). The rehabilitation subjects' percentage of predicted peak work rate also increased, exceeding the baseline test values by 4.9 ± 7.9 percentage points (P < .05). In contrast, small but statistically insignificant declines in percentage of predicted peak O2 (–3.1% ± 12.2%) and percentage of predicted peak work rate (–4.7% ± 10.8%) were observed among the control subjects. In this group, the percentage of predicted peak O2 declined in 11 subjects, was unchanged in 1, and improved in 6 (Fig 2B). The improvements in peak O2 and peak work rate achieved by the rehabilitation patients in the year that separated their initial and final exercise tests differed significantly from the corresponding changes observed among the control subjects during the same time period (both P < .01). Moreover, the magnitudes of the improvements achieved by the rehabilitation patients (ranging from 7.8% to 21.8%; Table 3) were substantial and clinically significant (Fig 3). At the final exercise test, the percentage of predicted peak O2 of the rehabilitation subjects was significantly better than the control subjects' (71% ± 16% vs 61% ± 11%; P < .05). The rehabilitation subjects' percentage of predicted peak work rate was also superior to the control subjects, but the difference did not achieve statistical significance (68% ± 19% vs 60% ± 14%; P = .16).
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In both groups, the peak exercise heart rate on the final exercise test did not differ significantly from the peak exercise heart rate on the baseline exercise test. However, in the rehabilitation group, the oxygen pulse at peak exercise was significantly higher (11.0% ± 16.1%) on the final exercise test compared with the baseline exercise test. In the control group, there was no difference between the peak exercise oxygen pulse on the baseline and final exercise tests. Linear regression analysis revealed that changes in the oxygen pulse correlated strongly with the concomitant changes in peak
O2 and accounted for 89% of the variation in the changes in peak O2 between the baseline and final exercise tests. A moderately strong correlation also existed between changes in peak oxygen pulse and changes in peak work rate (r = 0.54; P = .001).
The subjects' VAT data mirrored the pattern that emerged from their peak exercise data (Fig 3 and Table 3). Once again, the rehabilitation subjects' O2 at the VAT was significantly higher on their final exercise test compared with the baseline exercise test (P < .05). A small, statistically insignificant decline was observed among the control subjects. The improvements achieved by the rehabilitation patients differed significantly from the concurrent changes observed among the control subjects (P < .01). The results obtained when absolute or weight-corrected values for work rate and O2 were used in the analyses were similar to those obtained using percentage of predicted values.
Significant changes in baseline pulmonary function or in the slope of the minute ventilation (VE) versus carbon dioxide production relationship (an index of the efficiency of gas exchange during exercise15–17) were not observed in either group over the course of the study. However, the breathing reserve of the control subjects increased significantly (attributable primarily to a decrease in the peak exercise respiratory rate) compared with the baseline exercise test. This change was significantly different from that observed among the rehabilitation subjects.
Questionnaire Data
One year after they had completed their initial questionnaires, the rehabilitation patients reported that they exercised more frequently than they had the year before; the control subjects did not (P = .07). The rehabilitation patients also perceived that their exercise capacity was better than it was 1 year ago, whereas control subjects perceived that it was worse (P = .04).
On the CHQ Child Form-87, the rehabilitation patients' scores in the emotional, behavioral, and physical domains improved, whereas they declined among the control subjects. In each of these domains, the differences in the mean changes exceeded 7 points. Although these differences did not achieve statistical significance, a difference of 5 points is considered clinically meaningful.13
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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This study has demonstrated that many of the acute benefits of cardiac rehabilitation in children with congenital heart disease are maintained in most subjects 6.9 ± 1.6 months after the completion of the rehabilitation program. This is an important observation that has rarely been documented previously. Most past studies have examined only the acute, immediate effects of cardiac rehabilitation.1–10 Only Longmuir et al6,11 attempted to determine whether any acute benefits are sustained 3 to 4 months and 5 years after the completion of a rehabilitation program. Those studies were limited, however, by the use of a relatively brief (6-week), unmonitored home-exercise program, a low acuity of disease, a high (31%) incidence of "noncompliance," and the absence of metabolic measurements. In addition, their rehabilitation program was undertaken in the immediate postoperative period, and their results are, therefore, not comparable to the patients in our study, who had poor exercise function long after recovering from their last surgical procedure.
Important insights concerning the benefits of cardiac rehabilitation in children with congenital heart disease were also forthcoming from this study's comparison of the rehabilitation and control subjects. We found that the baseline exercise function, as well as the socioeconomic and demographic characteristics of the 2 groups, were quite similar. During the 1-year interval that separated the baseline and final exercise tests, both groups were managed similarly except for the fact that one participated in a 12-week rehabilitation program, whereas the other did not. At the time of the final exercise tests, the exercise function of the rehabilitation group remained significantly improved compared with baseline. These improvements seemed to have been associated with concomitant improvements in self-esteem, behavior, and emotional state. In contrast, improvements in exercise function, behavior, and psychosocial status were not detected in the control group. In fact, the patients who did not participate showed a trend toward declining exercise function.
It is important to note that the peak exercise heart rate and RER of the rehabilitation and control subjects were similar at baseline and did not change significantly at the final exercise test (Tables 2 and 3). These observations imply that the improvements observed among the rehabilitation subjects were not caused by differences in patient effort or motivation.
The data arising from the comparisons between the rehabilitation and control subjects are also important, because few previous studies of cardiac rehabilitation in children (ie, those of Longmuir et al6,11 and Fredriksen et al4) have included control groups. However, in the studies by Longmuir et al,6,11 the benefits of their exercise program were detectable only after the numerous noncompliant subjects were eliminated from their analyses. Similarly, in the study by Fredriksen et al4 (which only "introduced" children with repaired congenital heart defects to a variety of sports and other physical activities and did not use a well-structured exercise program, such as that used in the present study), little or no benefit could be demonstrated in the treatment group compared with the control subjects.
Hence, our study is the first to convincingly demonstrate that cardiac rehabilitation can provide significant and sustained benefits to children with congenital heart disease. We believe that the favorable outcomes obtained in our study are related to the flexibility of our rehabilitation program, the use of age-appropriate incentives, the low patient/staff ratio, the opportunity for prompt feedback and encouragement, and the high priority that was placed on pursuing activities that accommodated the individual needs/desires of our subjects. We also believe that our subjects were motivated by the opportunity to exercise in a child-oriented environment, with children their own age, carrying similar diagnoses.9
Our data also provide insights into the mechanisms responsible for the rehabilitation-related improvements in exercise function. The changes in peak O2 and peak work rate observed in this study were strongly associated with concomitant changes in oxygen pulse. Although the oxygen pulse is mathematically related to O2, it is not mathematically related to the work rate. We, therefore, believe that these observations are physiologically meaningful and indicate that the rehabilitation-related improvements in exercise function were mediated, at least in part, by improvements in oxygen pulse. These conclusions are consistent with the observations of Opocher et al,18 who found that a cardiac rehabilitation program had a beneficial effect on the exercise function and oxygen pulse of patients who have had a Fontan procedure. Because oxygen pulse is the product of stroke volume and oxygen extraction, we believe that changes in either or both of these variables account for the improvement in exercise function that was associated with cardiac rehabilitation.
Of note, the patients' heart rate at peak exercise was depressed significantly below values expected in healthy pediatric subjects. This chronotropic impairment is common after surgery for serious congenital heart disease.19–21 Cardiac rehabilitation seemed to have little impact on this component of the cardiovascular response to exercise.
We also observed that the control subjects' breathing reserve increased over the course of the study. This increase in breathing reserve was not associated with a significant improvement in any measure of pulmonary function. We, therefore, believe that this phenomenon reflects the fact that the exercise capacity of the control subjects declined slightly relative to the rehabilitation subjects (and normal subjects). The decline in exercise capacity was associated with a (relative) decline in VE at peak exercise. In contrast, the control subjects' pulmonary function (and, hence, their maximal voluntary ventilation [MVV]) did not decline relative to the rehabilitation subjects. Consequently, their breathing reserve [ie, 100 x (MVV – peak VE)/MVV] at peak exercise increased relative to the rehabilitation subjects.
It must be noted that this study was limited to patients with serious congenital heart disease. The value of cardiac rehabilitation in patients with milder forms of disease was not evaluated. It is also important to note that cardiac rehabilitation did not restore normal exercise function to our patients. Significant residual disabilities remained. However, the improvements in exercise function realized by the patients who participated in cardiac rehabilitation were consistent, substantial, and sustained. Furthermore, they seemed to be associated with favorable trends in the children's psychosocial function. We believe that the results of this study have compellingly established the value of cardiac rehabilitation in children. We feel that this therapy can benefit many children with congenital heart disease and should be incorporated into the care plan of these patients.
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ACKNOWLEDGMENTS |
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This study was supported by a grant from the Deborah Munroe Noonan Memorial Fund and by the Pediatric Heart Network (grant 5U01 HL068285).
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FOOTNOTES |
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Accepted Mar 31, 2006.
Address correspondence to Jonathan Rhodes, MD, Department of Cardiology, Children's Hospital, Boston, 300 Longwood Ave, Boston, MA 02115. E-mail: jonathan.rhodes{at}cardio.chboston.org
The authors have indicated they have no financial relationships relevant to this article to disclose.
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REFERENCES |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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- Ades PA, Coello CE. Effects of exercise and cardiac rehabilitation on cardiovascular outcomes. Med Clin North Am. 2000;84; 251 –265[CrossRef][Web of Science][Medline]
- Balfour IC, Drimmer AM, Nouri S, Pennington DG, Hemkens CL, Harvey LL. Pediatric cardiac rehabilitation.
Am J Dis Child. 1991;145
:627
–630
[Abstract/Free Full Text] - Bradley LM, Galioto FM Jr, Vaccaro P, Hansen DA, Vaccaro J. Effect of intense aerobic training on exercise performance in children after surgical repair of tetralogy of Fallot or complete transposition of the great arteries. Am J Cardiol. 1985;56 :816 –818[CrossRef][Web of Science][Medline]
- Fredriksen PM, Kahrs N, Blaasvaer S, et al. Effect of physical training in children and adolescents with congenital heart disease. Cardiol Young. 2000;10 :107 –114[Web of Science][Medline]
- Goldberg B, Fripp RR, Lister G, Loke J, Nicholas JA, Talner NS. Effect of physical training on exercise performance of children following surgical repair of congenital heart disease.
Pediatrics. 1981;68
:691
–699
[Abstract/Free Full Text] - Longmuir PE, Turner JA, Rowe RD, Olley PM. Postoperative exercise rehabilitation benefits children with congenital heart disease. Clin Invest Med. 1985;8 :232 –238[Web of Science][Medline]
- Minamisawa S, Nakazawa M, Momma K, Imai Y, Satomi G. Effect of aerobic training on exercise performance in patients after the Fontan operation. Am J Cardiol. 2001;88; 695 –698[CrossRef][Web of Science][Medline]
- Ruttenberg HD, Adams TD, Orsmond GS, Conlee RK, Fisher AG. Effects of exercise training on aerobic fitness in children after open heart surgery. Pediatr Cardiol. 1983;4 :19 –24[CrossRef][Web of Science][Medline]
- Rhodes J, Curran TJ, Camil L, et al. Impact of cardiac rehabilitation on the exercise function of children with serious congenital heart disease.
Pediatrics. 2005;116
:1339
–1345
[Abstract/Free Full Text] - Washington RL. Cardiac rehabilitation programmes in children. Sports Med. 1992;14 :164 –170[Web of Science][Medline]
- Longmuir PE, Tremblay MS, Goode RC. Postoperative exercise training develops normal levels of physical activity in a group of children following cardiac surgery. Pediatr Cardiol. 1990;11 :126 –130[CrossRef][Web of Science][Medline]
- Wasserman K, Hansen JE, Sue DY, Casaburi R, Whipp BJ. Principles of Exercise Testing and Interpretation. 3rd ed. Philadelphia, PA: Lippincott; 1999
- Landgraf JM, Abetz L, Ware JE. The CHQ User's Manual. 2nd ed. Boston, MA: HealthAct; 1999
- Wasserman K. The anaerobic threshold measurement to evaluate exercise performance. Am Rev Respir Dis. 1984;129 :S35 –S40[Web of Science][Medline]
- Chua TP, Ponikowski P, Harrington D, et al. Clinical correlates and prognostic significance of the ventilatory response to exercise in chronic heart failure. J Am Coll Cardiol. 1997;29 :1585 –1590[Abstract]
- Clark AL, Gatzoulis MA, Redington AN. Ventilatory responses to exercise in adults after repair of tetralogy of Fallot.
Br Heart J. 1995;73
:445
–449
[Abstract/Free Full Text] - Rhodes J, Dave A, Pulling MC, et al. Effect of pulmonary artery stenoses on the cardiopulmonary response to exercise following repair of tetralogy of Fallot. Am J Cardiol. 1998;81 :1217 –1219[CrossRef][Web of Science][Medline]
- Opocher F, Varnier M, Sanders SP, et al. Effects of aerobic exercise training in children after the Fontan operation. Am J Cardiol. 2005;95 :150 –152[CrossRef][Web of Science][Medline]
- Driscoll DJ, Feldt RH, Mottram CD, Puga FJ, Schaff HV, Danielson GK. Cardiorespiratory response to exercise after definitive repair of univentricular atrioventricular connection. Int J Cardiol. 1987;17 :73 –81[CrossRef][Web of Science][Medline]
- Grant GP, Mansell AL, Garofano RP, Hayes CJ, Bowman FO Jr, Gersony WM. Cardiorespiratory response to exercise after the Fontan procedure for tricuspid atresia. Pediatr Res. 1988;24 :1 –5[Web of Science][Medline]
- Reybrouck T, Weymans M, Stijns H, Van der Hauwaert LG. Exercise testing after correction of tetralogy of Fallot: the fallacy of a reduced heart rate response. Am Heart J. 1986;112 :998 –1003[CrossRef][Web of Science][Medline]
PEDIATRICS (ISSN 1098-4275). ©2006 by the American Academy of Pediatrics
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