Effect of pulmonary artery angioplasty on exercise function after repair of tetralogy of Fallot.

BACKGROUND: The slope of the minute ventilation versus CO2 production relationship (VE/VCO2 slope) is an index of gas exchange efficiency during exercise. In patients with repaired tetralogy of Fallot (rTOF), it correlates negatively with exercise capacity and is one of the best predictors of peak oxygen consumption (VO2). In these patients, the magnitude of the VE/VCO2 slope is related to the severity of pulmonary blood flow maldistribution (PBFM). The purpose of this study was to determine whether, in patients with rTOF, improvements in PBFM after a successful balloon angioplasty procedure (BAP) result in improvements in peak VO2 and gas exchange during exercise. METHODS: Seventeen patients with rTOF and residual pulmonary artery stenoses referred for BAP were recruited. Exercise tests were performed and PBFM determined before and after BAP. RESULTS: Nine patients (group 1) had a successful BAP (ie, improvement of >5 percentage points in PBFM); 8 did not (group 2). Patients in group 1 had significantly greater improvements in VE/VCO2 slope, peak VO2, and peak oxygen pulse (an index of forward stroke volume at peak exercise) than did patients in group 2. A significant correlation existed between the improvement in PBFM and the decline in the VE/VCO2 slope (r = -0.70, P = .002). Changes in peak oxygen pulse accounted for 89% of the improvement in peak VO2. CONCLUSIONS: In these patients, a successful BAP resulted in improved peak VO2 and more efficient gas exchange during exercise. The improvement in peak VO2 appeared to be mediated by an increase in forward stroke volume.

Sustained effects of cardiac rehabilitation in children with serious congenital heart disease.

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 (approximately 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.

Impact of cardiac rehabilitation on the exercise function of children with serious congenital heart disease.

OBJECTIVES: The exercise capacity of children with congenital heart disease (CHD) is often depressed. This depression is thought to be attributable to (1) residual hemodynamic defects and (2) deconditioning secondary to physical inactivity. We hypothesized that this latter component would be ameliorated by a formal cardiac rehabilitation program designed specifically for children. The objective of this study was to characterize the effect of a cardiac rehabilitation program on the exercise performance of children with CHD and to define the physiologic mechanisms that might account for any improvements that are observed. METHODS: Nineteen patients with CHD who were referred for exercise testing and found to have a peak oxygen consumption (VO2) and/or peak work rate <80% of predicted were enrolled in the study. Sixteen patients (11 Fontan patients, 5 with other CHD) completed the program and had postrehabilitation exercise tests, results of which were compared with the prerehabilitation studies. RESULTS: Improvements were found in 15 of 16 patients. Peak VO2 rose from 26.4 +/- 9.1 to 30.7 +/- 9.2 mL/kg per min; peak work rate from 93 +/- 32 to 106 +/- 34 W, and the ventilatory anaerobic threshold from 14.2 +/- 4.8 to 17.4 +/- 4.5 mL/kg per min. The peak heart rate and peak respiratory exchange ratio did not change, suggesting that the improvements were not attributable merely to an increased effort. In contrast, the peak oxygen pulse rose significantly, from 7.6 +/- 2.8 to 9.7 +/- 4.1 mL/beat, an improvement that can be attributed only to an increase in stroke volume and/or oxygen extraction at peak exercise. No patient experienced rehabilitation-related complications. CONCLUSION: Cardiac rehabilitation can improve the exercise performance of children with CHD. This improvement is mediated by an increase in stroke volume and/or oxygen extraction during exercise. Routine use of formal cardiac rehabilitation may greatly reduce the morbidity of complex CHD.