Study objectives: To assess exercise tolerance and determine the distinct role of cardiac, respiratory, or peripheral factors on it after delayed surgical repair in patients with tetralogy of Fallot.
Design: The aerobic exercise capacity of 15 adult patients (mean [[+ or -] SD] age, 21 [+ or -] 6; age range, 9 to 30 years) undergoing successful total correction at a mean age of 12 [+ or -] 5 years (patients) was compared to healthy, matched control subjects by using right ventricle echocardiography, resting spirometry, and cardiopulmonary exercise tests at a mean postoperative time of 7.5 [+ or -] 4.6 years.
Setting: Tertiary care referral centers.
Patients: Fifteen adult patients (mean age, 21 [+ or -] 6 years; age range, 9 to 30 years) undergoing successful total correction at a mean age of 12 [+ or -] 5 (patients) and 15 healthy, matched volunteers (control subjects).
Results: There was evidence for a slight right ventricular diastolic dysfunction in the patients. Mean FVC (88 [+ or -] 9% vs 109 [+ or -] 12% predicted, respectively) and FE[V.sub.1] (89 [+ or -] 9% vs 109 [+ or -] 12% predicted, respectively), although being within the normal range, were also decreased in comparison to those of control subjects (p < 0.0001). Maximal oxygen consumption (V[O.sub.2]max) decreased in both groups (55 [+ or -] 16% vs 61 [+ or -] 23% predicted, respectively; p = 0.5); however, there were more individuals with severely decreased values among the patients (p = 0.05). V[O.sub.2] at the anaerobic threshold was also decreased in patients (33 [+ or -] 15% vs 51 [+ or -] 8% predicted, respectively; p = 0.004). The maximum tolerable exercise time was 17.3 [+ or -] 4.5 min in patients vs 21.2 [+ or -] 6.4 min in eontrol subjects (p = 0.06).
Conclusions: The exercise capacity after delayed repair was good in general compared to matched control subjects; however, exercise capacity may be slightly limited by ventilatory dysfunction, low anaerobic threshold, and lack of physical fitness despite New York Heart Association class improvement after undergoing the operation.
Key words: exercise test; exercise tolerance; metabolism; quality of life; respiratory function tests; tetralogy of Fallot
Abbreviations: BR = breathing reserve; HR = heart rate; MET = metabolic equivalent; MVV = maximum voluntary ventilation; NYHA = New York Heart Association; RER = respiratory exchange ratio; RVEF = right ventricular ejection fraction; Sp[O.sub.2] = pulse oximetric saturation. VD/VT = physiologic dead space ventilation. VD/VTpeak = physiologic dead space ventilation at peak exercise. VD/VTrest = physiologic dead space ventilation at rest. VE/VC[O.sub.2] = carbon dioxide production; VEmax = maximum minute ventilation; V[O.sub.2] = oxygen consumption. V[O.sub.2]at = oxygen consumption at the anaerobic threshold. V[O.sub.2]max = maximal oxygen consumption
The current approach to treating a patient with tetralogy of Fallot is to repair the defect in infancy, and the benefits of early repair are well-established in the medical literature beyond any doubt. Early repair is advocated in these patients to allow for nonrestricted cardiopulmonary development, as well as to avoid possible complications involving other organs and systems. (1,2) Nevertheless, we still encounter patients with this diagnosis and/or who are referred for cardiac surgery later in life. There is such a population, although not as large as those who received medical attention in infancy, especially in developing countries. Although a successful outcome after primary repair in infancy has been explicitly demonstrated by many contemporary studies, the outcome after delayed repair is still obscure, and there are gaps in our knowledge as to what to expect from the surgical intervention in these patients after a delayed but otherwise (technically) good operation.
The primary goal of the present study was to investigate exercise tolerance in subjects after "delayed repair" of the tetralogy of Fallot, and to compare those results to an age-matched and sex-matched group of healthy subjects. To determine the distinct role of cardiac, respiratory, or peripheral factors in the multifactorial exercise capacity limitation, we studied right ventricle dynamics, lung function, and exercise performance both in patients and in an active, but non-sporting control group.
MATERIALS AND METHODS
Study Population: Demographics
Fifteen patients (14 male, 1 female) undergoing total surgical correction in our department for the treatment of tetralogy of Fallot entered this study (the study group; called patients). Patients were selected randomly from among those who had no residual shunting, no signs or episodes of congestive heart failure, and no significant postoperative complication. The mean ([+ or -] SD) age was 21 [+ or -] 6 years (age range, 9 to 30 years), and, at the time of surgical repair, the mean age of the patients was 12 [+ or -] 5 years. The mean postoperative period was 7.5 [+ or -] 4.6 years (range, 2 to 16 years). The control group (ie, control subjects) consisted of 15 age-matched, sex-matched, and body surface area-matched, nonsporting individuals (13 male and 2 female; p = 0.5) who had been randomly selected from among the healthy volunteers. The mean age was 23 [+ or -] 6 years in this group (p = 0.1). All subjects were studied by right ventricular echocardiography, resting spirometry, and a symptom-limited treadmill exercise test. Informed patient consent and institutional board approval were obtained. All individuals were subjected to a detailed physical examination, electrocardiography, teleradiography, and routine laboratory tests prior to study.
Echocardiographic Evaluation of Right Ventricular Functions
Echocardiographic assessment was performed (GE Vingmed System Five; CVS; Aliso Viejo, CA) device, using two-dimensional echocardiography, pulsed wave Doppler echocardiography, continuous Doppler echocardiography, and tissue Doppler techniques. The right ventricular ejection fraction (RVEF) was calculated by single-plane volume subtraction method via the apical four-chamber view.
Resting spirometry was repeated three times for each individual, and the best measurement was recorded. Before the exercise tests, resting spirometry (SensorMedics; Yorba Linda, CA) was conducted according to European Respiratory Society standards, and FVC, FE[V.sub.1], forced expiratory flow rate (midexpiratory phase), peak expiratory flow rate, vital capacity, maximum voluntary ventilation (MVV), and tidal volume were measured. The results were also described as the percentage of predicted values calculated from equations that had been reported as norms.
Cardiopulmonary Exercise Test (Ergospirometry)
All individuals were subjected to a symptom-limited treadmill test on an electronically braked treadmill ergometer accompanied by a computerized module (Vmax 29; SensorMedics; Yorba Linda, CA), gradually increasing the exercise load to the point of fatigue, according to modified Bruce protocol. Previously published guidelines for contraindications and criteria for ending an exercise test were used. (3) A standard open-circuit method was used to collect expired gas through a breathing apparatus mounted on a face mask. The analyzer was calibrated before each test using known concentrations of oxygen and carbon dioxide. Continuous measurements of expired gas values were analyzed at 20-s intervals. Oxygen saturation was measured via a photometer applied to the ear lobe.
Measured Parameters and Physiologic Limits: During the test, measurements of BP, ECG, heart rate (HR), HR reserve (ie, predicted HR - actual HR at peak exercise; considered abnormal if exceeds 15 beats/min), respiratory rate, oxygen consumption (V[O.sub.2]), maximum minute ventilation (VEmax), carbon dioxide output, respiratory exchange ratio (RER), and pulse oximetric saturation (Sp[O.sub.2]), end-tidal carbon dioxide, end-tidal oxygen, and carbon dioxide production (VE/VC[O.sub.2]) were recorded continuously. A maximal V[O.sub.2] (V[O.sub.2]max) level of < 85% predicted was considered to be under the normal limits, and a value < 60% was considered to be severely decreased. The V[O.sub.2] value at the anaerobic threshold (V[O.sub.2]at) [ie, the V[O.sub.2] value at which oxygen demand exceeds the ability of the circulation to sustain the aerobic metabolism and the anaerobic metabolism begin to support the exercise] was recorded (ie, the V[O.sub.2]at) and was considered to be abnormal if it was < 40% of the predicted V[O.sub.2]max. Breathing reserve (BR) was calculated as the percentage of the VEmax/MVV ratio and was interpreted as a ventilatory limitation to exercise if > 75%. The metabolic equivalent (MET) was calculated as follows: 1 MET equals 3.5 mL of [O.sub.2]/kg/min. The physiologic dead space ventilation (VD/VT), which is a useful parameter in determining ventilation/perfusion imbalance, was calculated at rest (VD/VTrest) and at peak exercise (VD/VTpeak). VD/VTrest values of > 0.3 to 0.4 and VD/VTpeak values of 0.19 to 0.21 were regarded as dead space ventilation. The decrease in Sp[O.sub.2] during exercise ([DELTA]Sp[O.sub.2] = Sp[O.sub.2] at rest - Sp[O.sub.2] at peak exercise) was regarded as abnormal if it was > 4%, and the exercise Sp[O.sub.2] was considered to be markedly decreased if it was < 84%.
RER was used as an "index of maximal exertion," since RER is an extremely useful guide to the exercise supervisor, indicating the ensuing attainment of exertion. Values of < 1.0 at peak exercise generally signify inadequate effort or poor motivation on the part of the patient. An REB value of 1.1,5 to 1.20 during exercise has been suggested as subsidiary evidence that a "tree" V[O.sub.2]max has been attained. (4)
All statistical analyses were performed using a statistical software package (SPSS, version 6.0; SPSS Inc; Chicago, IL). Values are given as the mean [+ or -] SD. Comparisons between the groups were made by Student t test, Wilcoxon matched pairs signed rank test, Mann Whitney U test, [chi square] test, and Fisher exact test where applicable. The Pearson correlation test was applied to analyze correlations among the parameters. A p value [less than or equal to] 0.05 was considered to be statistically significant.
Operative Data and Outcome (Patients)
The mean extracorporeal circulation time was 103 [+ or -] 25 min (range, 60 to 151 min), while the mean aortic clamping duration was 67 [+ or -] 18 min (range, 39 to 98 min). The mean ICU stay was 2 [+ or -] 0.9 days (range, 1 to 4 days), and the mean hospitalization duration was 19 [+ or -] 11 days (range, 7 to 48 days). Preoperative hemoglobin level (17 [+ or -] 2.3 mg/dL) and hematocrit level (52 [+ or -] 9%) were significantly decreased after the operation (14 [+ or -] 1.1 mg/dL and 44 [+ or -] 3%, respectively; p = 0.003). The mean preoperative systolic pulmonary artery pressure increased from 17 [+ or -] 3 to 25 [+ or -] 7 mm Hg (p < 0.0001), while the mean peak systolic pulmonary gradient decreased from 94 [+ or -] 19 mm Hg preoperatively to 20 [+ or -] 9 mm Hg postoperatively (p < 0.0001). A transannular patch was used in the relief of right ventricular outflow tract stenosis in all patients. All patients had 1+ to 2+ (mild) pulmonary insufficiency postoperatively. The mean residual transannular gradient was 10 [+ or -] 12 mm Hg (range, 0 to 40 mm Hg). The improvement in New York Heart Association (NYHA) class after the operation was significant (from an average of 2.73 to 1.06; p = 0.007).
Comparison Between the Patients and Control Subjects
There was no difference between the patients and control subjects in regard to sex, age, height, weight, hemoglobin level, and hematocrit level (Table 1).
Echocardiographic Comparison: Echocardiographic parameters were compared in Table 2. There was no significant difference between the groups in regard to central pulmonary artery diameters (ie, main, left, and right pulmonary arteries) [Table 2]. The mean systolic pulmonary artery pressures were not different between the groups (patients, 25 [+ or -] 7 mm Hg; control subjects, 23 [+ or -] 3 mm Hg; p = 0.2). The average RVEF was within normal limits in the both groups; however, it was slightly lower in the patients (50 [+ or -] 7%) than in the control subjects (56 [+ or -] 4%; p = 0.02). The mean right ventricular systolic pressure on the other hand, was greater in the patients (45 [+ or -] 10 vs 23 [+ or -] 3 mm Hg, respectively; p < 0.0001). When diastolic parameters of the fight ventricular indexes were compared, the mean isovolumetric relaxation time was significantly shorter in patients (64 [+ or -] 13 vs 79 [+ or -] 22 millisecond, respectively; p = 0.03) and the mean E/A ratio (Doppler early diastolic filling velocity/Doppler delayed diastolic filling velocity) was significantly smaller in patients (1.2 [+ or -] 0.3 vs 1.7 [+ or -] 0.4, respectively; p = 0.002). The E/A ratio was abnormal (ie, < 1) in 6 patients, while the E/A ratio was normal in 14 of 15 control subjects (p = 0.04). The mean deceleration time was not different between patients and control subjects (232 [+ or -] 75 vs 198 [+ or -] 30 millisecond, respectively; p = 0.1). A tissue Doppler study revealed no difference in E' values (tissue Doppler early diastolic wave) between the groups (patients, 0.11 [+ or -] 0.04 cm/s; control subjects, 0.13 [+ or -] 0.03 cm/s; p = 0.07).
Resting Spirometry: Resting spirometry (Table 3) revealed significantly decreased FVC (88 [+ or -] 9% vs 109 [+ or -] 12% predicted, respectively; p < 0.0001), vital capacity (86 [+ or -] 9% vs 107 [+ or -] 11% predicted, respectively; p < 0.0001), FE[V.sub.1] (89 [+ or -] 12% vs 108 [+ or -] 13% predicted, respectively; p < 0.0001), and forced expiratory flow, midexpiratory phase values (86 [+ or -] 22% vs 108 [+ or -] 31% predicted, respectively; p < 0.03) in patients in comparison to those in control subjects; however, all values were in the normal range (ie, > 85% predicted).
Cardiopulmonary Exercise Test: Ergospirometric data are presented in Table 4 in detail.
RER as an Index of Maximal Exertion: The subjects achieved an RER of > 1.0 during graded exercise. The mean RER was 1.08 [+ or -] 0.1 in patients vs 1.15 [+ or -] 0.1 in control subjects (Table 4), as subsidiary evidence that a true V[O.sub.2]max had been attained. This implied good reliability for the ergospirometric test.
V[O.sub.2]max: Although the mean difference between patients and control subjects was not significant statistically (27 [+ or -] 8 vs 27 [+ or -] 10 mL/kg/min, respectively; p = 0.9) [Table 4], there were more individuals with severely decreased (ie, < 60% of the predicted) V[O.sub.2]max among the patients (12 individuals) than among the control subjects (7 individuals; p = 0.05) [Table 5, Fig 1]. The mean V[O.sub.2]max for both patients and control subjects were below the predicted values.
[FIGURE 1 OMITTED]
V[O.sub.2]at: The average V[O.sub.2]at was significantly decreased for patients (1.11 [+ or -] 0.45 L/min) compared to that for control subjects (1.57 [+ or -] 0.24 L/min; p = 0.02). The V[O.sub.2]at was 33 [+ or -] 15% predicted in patients vs 51 [+ or -] 8% predicted in control subjects (p = 0.006) [Tables 4, 5, Fig 2).
[FIGURE 2 OMITTED]
METs: The maximum exerted MET values were similar between the groups (7.73 [+ or -] 2.25 vs 7.69 [+ or -] 2.82, respectively; p = 0.9), which is indicative of a good ability to cope with die metabolic requirements of daffy activities.
HR: There was no significant difference between the groups in regard to average HR (in beats per minute or percent predicted) and HR reserve. The increase in HR as a response to exercise was abnormal in six patients and three control subjects (p = 0.2).
VEmax: No difference was detected between the groups in regard to mean VEmax (patients, 70 [+ or -] 20 L/min; control subjects, 91 [+ or -] 42 L/min; p = 0.09) and its percent predicted (patients, 62 [+ or -] 12% predicted; control subjects, 66 [+ or -] 21% predicted; p = 0.4).
BR (VEmax/MVV Ratio): The mean BR was 62 [+ or -] 12% in patients vs 66 [+ or -] 21% in control subjects (p = 0.4), with values well within the normal range in both groups.
VE/VC[O.sub.2] Ratio: The VE/VC[O.sub.2] ratio was abnormal (> 40) in four patients and one control subject (p = 0.3). The mean VE/VC[O.sub.2] ratio was higher in patients (39.5 [+ or -] 6.8) than in control subjects (31.8 [+ or -] 4.9; p = 0.01).
VD/VTrest and VD/VTpeak: The mean VD/VTrest was higher in patients (0.53 [+ or -] 0.04) than in control subjects (0.46 [+ or -] 0.08; p = 0.004). VD/VTrest was abnormal in 14 patients and 11 control subjects (p = 0.05). The mean VD/VTpeak was 0.25 [+ or -] 0.09 in patients and 0.19 [+ or -] 0.10 in control subjects (p = 0.1). The VD/VTpeak was abnormal in 12 patients five control subjects (p = 0.004). These results represent a ventilation/perfusion mismatch due to insufficient ventilation and probably VD/VT both at rest and at peak exercise.
Sp[O.sub.2]: Mean resting Sp[O.sub.2] (patients, 94 [+ or -] 4%; control subjects, 93 [+ or -] 4%; p = 0.4), Sp[O.sub.2] at peak exercise (patients, 84.93 [+ or -] 3.15%; control subjects, 85.64 [+ or -] 2.85%; p = 0.5), and respiratory rate at peak exercise (patients, 44 [+ or -] 5 breaths/min; control subjects, 40 [+ or -] 9 breaths/min; p = 0.2) did not differ between the groups. Exercise Sp[O.sub.2] was within normal limits (> 84%) in both groups. However, the [Delta]Sp[O.sub.2] exceeded 4% in both patients (9.2 [+ or -] 5.5%) and control subjects (6.9 [+ or -] 5.6%).
The mean maximum tolerable exercise duration was 17.3 [+ or -] 4.5 min in patients vs 21.2 [+ or -] 6.4 min in control subjects (p = 0.06). The reason for the termination of the test was general fatigue in all subjects. A positive correlation existed between age and exercise duration (r = 0.446; p = 0.013). Please refer to Tables 4 and 5 for more detailed ergospirometric data.
Although the standard approach in the treatment of a patient with tetralogy of Fallot is early surgical repair of the heart in infancy in order to have nonrestricted cardiopulmonary development and to avoid possible complications in organs systems, (1,2,4,5) there is still a population that is referred for cardiac surgery late in life, especially in developing countries. Outcomes after delayed repair are still obscure, and there are gaps in our knowledge as what to expect for these patients after a delayed but otherwise (technically) good operation.
Having a sufficient physical activity level during everyday life is essential to cope with the necessities of social, business, and private life. The cardiac limitations in patients with tetralogy of Fallot are expected to improve to a great extent after total correction; however, there are references to decreased aerobic capacity despite greatly improved NYHA functional class in these patients even after a successful repair. Among the possible reasons are residual lesions or surgical complications. (3,4,6) After eliminating the presence of such factors by hemodynamic examinations, efforts should be directed toward the assessment of exercise response and the possible factors responsible for this limitation. There are three major determinants of exercise tolerance, namely, cardiac, respiratory, and peripheral (ie, skeletal muscle) factors. (7)
Exercise testing is a useful objective marker of functional capacity in patients undergoing surgical corrective procedures for congenital heart disease. (8-10) In this study, cardiopulmonary exercise tests were performed in 15 patients undergoing total corrective surgery to assess their exercise capacity and to compare them to an active, non-sporting, age-matched and sex-matched group. We studied possible relations among ventilation, exercise capacity, and right ventricular function. Among the possible limitations of this study are the relatively small sampling population and the lack of comparison to preoperative ergospirometry due to the potential hazards of strenuous exercise on a population with uncorrected cyanotic heart disease.
There are many references to the benefits of early repair in this subset of patients. (1,2) James et al (1) demonstrated an inverse correlation between the age at operation and exercise capacity. Others have reported (5) no influence of the age at operation on oxygen use during exercise and exercise capacity. Another parameter that may be affected by the age of the subject at the time of surgery is exercise capacity and duration. Rowe et al (5) suggested that undergoing surgery before the age of 11 years does not have a negative impact on exercise tolerance, but that after that age there may remain sequelae in exercise capacity due to long-lasting myocardial hypoxia. Our patients underwent surgical repair at a considerably old age (mean age at operation: 12 [+ or -] 5 years), and therefore we aimed to investigate the extent to which they benefited from the delayed repair.
Impaired right heart function due to residual lesions or developmental issues is one factor that is held responsible for poor exercise capacity in these patients. (5,6,11) However, we found that, apart from slightly disturbed diastolic functions, the right ventricular functions were very much in the normal range. The decrease in the average RVEF in patients compared to that in control subjects was significant statistically, but not clinically. Further, ejection fraction is a highly afterload-dependent parameter, and the right ventricular afterload in patients was higher than that in control subjects due to mild residual outflow gradients. There is a good possibility that intracavitary right ventricular pressure may further increase during exercise, and this may also contribute to the exercise limitation.
There have been reports emphasizing the role of decreased pulmonary capacity on limited exercise tolerance. After total surgical correction, NYHA class improves to a great extent in these patients; however, the ventilatory parameters may remain limited during exercise as well as at rest as revealed by spirometry due to residual lung pathology. (5,12) Zapletal et al (12) and Hruda et al (13) found abnormal resting spirometry in 93% of the preoperative patients and in 83% of the postoperative patients undergoing intracardiac repair for tetralogy of Fallot. They interpreted these results as a sign of permanent sequelae of early lung damage from abnormal pulmonary hemodynamics. Right ventricular outflow tract obstruction in patients with tetralogy of Fallot is associated with low pulmonary blood flow, which may lead to poor bronchopulmonary tree and parenchyreal development as well as small airway obstruction. (2,14,15) Although the gas-exchange unit is believed to continue its development until the age of 8 years, the great majority of our patients were beyond that age. At that point, the retardation may not compensable. Therefore, correction at an earlier age is also preferred for a normal pulmonary development. According to Lillehei and colleagues, (16) a relatively low residual peak systolic pulmonary gradient (ie, < 20 mm Hg) leads to a normal pulmonary artery and annulus development, while high residual gradients tend to increase with time. Lillehei et al (16) emphasized the importance of the amount of pulmonary blood flow on the development of the pulmonary artery and its branches. In this context, a relatively low residual gradient and mild pulmonary insufficiency in our series may be the reason for the seemingly unrestricted development of main pulmonary arteries and, consequently, their almost equal diameters in comparison to those of control subjects. Therefore, negatively affected pulmonary parenchyreal development due to underlying right-sided cardiac malformation is not expected if this has not already occurred before the surgical correction. In our study, although the resting spirometry revealed significantly lower FVC and FE[V.sub.1] values in patients than in control subjects, they were within normal predicted range. Further, BR was within the normal range in both groups, implying no respiratory limitation to exercise.
There remains another determinant of exercise tolerance; the peripheral factors, which can be expressed as skeletal muscle condition. Our study revealed low V[O.sub.2]max values as well as V[O.sub.2]at values, not only in patients undergoing total corrective surgery but also in the healthy matched control subjects, most probably due to sedentary lifestyle and lack of physical fitness in both groups. RER values of approximately 1.1 imply a good motivation to exercise and that a satisfactory level of effort has been achieved by the subjects. (3) Another important parameter in estimating exercise tolerance is exercise duration. There was a difference of borderline significance (p = 0.06) between the patients and the healthy control subjects in terms of the mean maximum tolerable exercise duration (17.3 [+ or -] 4.5 vs 21.2 [+ or -] 6.4 min, respectively). Further, there were significantly more subjects with abnormally decreased V[O.sub.2]max among the patients (n = 12) than among control subjects (n = 7; p = 0.05). Again, the V[O.sub.2]at was significantly lower in patients than in control subjects (p = 0.006). Therefore, a limitation to exercise to some degree should be present in these patients. The reason that the difference did not become significant in terms of V[O.sub.2]max may be the limited number of subjects in the sampling volume.
In conclusion, as the similarity between the groups in terms of the maximum exerted MET values (7.73 [+ or -] 2.25 vs 7.69 [+ or -] 2.82, respectively, p = 0.9) indicate, the exercise capacity in patients undergoing late surgical repair was in general good compared with matched control subjects. However, ventilatory dysfunction, low anaerobic threshold, and lack of physical fitness may limit exercise tolerance despite NYHA class improvement after the operation. Neither the right ventricular dynamics, nor the pulmonary reserve alone should be held as the sole responsible factor for this obscure exercise limitation in patients undergoing total corrective surgery. The slight distortion in diastolic right ventricular functions, low FVC, low FE[V.sub.1], and lack of exercise are among the possible contributing factors. Even low-outflow gradients and mild pulmonary regurgitation may increase during exercise, to a level at which a limitation becomes evident. Most probably, all of these above-mentioned factors are acting together.
This implies that the pathologic responses that are not manifested during daily life may be possible to uncover by cardiopulmonary exercise testing. The poor exercise tolerance in our patients may be due partly to the lack of a continuous postoperative cardiovascular and pulmonary rehabilitation program. Therefore, we think that patients should enter a complete postoperative cardiopulmonary rehabilitation program and be encouraged to exercise, as far as their hemodynamic condition allows, since it has been proven possible to greatly improve the exercise tolerance in these patients by establishing a reasonable, appropriate cardiopulmonary rehabilitation program. (9,17,18) The information obtained by ergospirometry is not only useful in the evaluation of these patients, but is also necessary to establish safe, yet effective exercise guidelines for postoperative rehabilitation.
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Manuscript received November 2, 2004; revision accepted January 12, 2005.
Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml).
Correspondence to: Kerem M. Vural, MD, N. Tandogan cad. 5/6 Kavaklidere, 06540 Ankara, Turkey; e-mail: firstname.lastname@example.org
* From the Departments of Cardiovascular Surgery (Drs. Ercisli, Vural, Sener, and Tasdemir) and Cardiology (Dr. Tufeckioglu), Yuksek Ihtisas Hospital of Turkey, Ankara, Turkey; and the Ankara Physical Medicine and Rehabilitation Education and Research Hospital (Drs. Gokkaya and Koseoglu), Ankara, Turkey.
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