Physiologic decrease of ventilatory response to exercise in the second decade of life in healthy children.

BACKGROUND: Cardiopulmonary exercise testing is increasingly used in children with congenital heart defects. Because of changes related to growth, the interpretation of exercise test results heavily relies on the presence of normative data. There is growing interest in the assessment of the ventilatory response to exercise in children with congenital heart disease, but normative data are lacking. METHODS: We studied 243 consecutive children (age, 13.2 ± 2.1 years; 128 boys) with maximal cardiopulmonary exercise testing. All children had normal clinical examination and echocardiograms. In all children, the slope of the relationship between minute ventilation and carbon dioxide production (VE/VCO(2) slope) was calculated using both only data until the respiratory compensation point (VE/VCO(2RC)) and using data until peak exercise (VE/VCO(2Peak)). RESULTS: The exercise test was maximal in all children (peak respiratory exchange ratio, 1.2 ± 0.1). For all the cohorts, VE/VCO(2Peak) slope was 28.2 ± 3.7; and VE/VCO(2RC) slope was 24.5 ± 3.0, whereas peak oxygen uptake was 94.6% ± 14.0% of predicted value. Baseline spirometric function was normal in all children (vital capacity, 100% ± 14% and forced expired volume in the first second 97% ± 13% of predicted). From the age of 10 to 16 years, we observed a progressive decrease in both VE/VCO(2Peak) and VE/VCO(2RC) slopes (-0.833 and -0.705 per each year), with the highest reduction observed in boys. Gender-specific percentiles for both VE/VCO(2Peak) and VE/VCO(2RC) slopes were constructed. CONCLUSION: Ventilatory response to exercise expressed as VE/VCO(2) slope seems to decrease progressively in the second decade of life. Because of age-related changes, interpretation of VE/VCO(2) slopes in this age range should be based on the reported percentiles rather than on the absolute values.

The EPICure study: maximal exercise and physical activity in school children born extremely preterm.

RATIONALE: Evidence regarding exercise capacity and physical activity in children born extremely preterm (EP) is limited. Since survivors remain at high risk for developing bronchopulmonary dysplasia (BPD) and long-term pulmonary sequelae, reductions in exercise capacity and activity levels may be present. OBJECTIVES: To compare maximal exercise ventilation characteristics and physical activity levels at 11 years of age in children born EP (<25 completed weeks gestation) with those of full-term controls. METHODS: Participants performed spirometry, body plethysmography and gas transfer testing. A peak exercise test was performed on a cycle ergometer. Physical activity was monitored by accelerometry for 7 days. RESULTS: Lung function and exercise results were obtained in 38 EP children (71% prior BPD) and 38 controls. Those born EP had significantly lower Z-scores (mean (95% CI) of difference) for forced expiratory volume in 1 s (FEV(1); -1.74 (-2.25 to -1.23) and gas transfer (-0.73 (-1.31 to -0.17), and significantly greater Z-scores for residual volume (RV; 0.58 (0.10 to 1.10)) and RV/total lung capacity (TLC; 0.74 (0.29 to 1.19)). EP birth was associated with a significant reduction in peak oxygen consumption. EP children employed greater breathing frequencies and lower tidal volumes during peak exercise. No differences were observed in physical activity between groups. CONCLUSIONS: The reduction in peak oxygen consumption in children born EP, and alterations in ventilatory adaptations during peak exercise were not explained by differences in physical activity, but probably reflects the long-term pathophysiological impact of EP birth.

Comparison of 6-min walk test distance and cardiopulmonary exercise test performance in children with pulmonary hypertension.

OBJECTIVE: To assess the relationship between 6-min walk test (6MWT) distance and variables of cardiopulmonary exercise testing (CPET) in children with pulmonary arterial hypertension (PAH). DESIGN: Retrospective study. SETTING: Tertiary hospital. PATIENTS: Children with PAH. INTERVENTIONS: CPETs and 6MWTs. MAIN OUTCOME MEASURES: Correlations between variables of CPET and 6MWT distance. RESULTS: 41 exercise studies were included: 15 in children with idiopathic PAH (mean age 13.0±3.0 years; 9 female), 18 in children with PAH associated with congenital heart disease (age 14.8±2.8 years; 7 female) and 8 in children with Eisenmenger syndrome (age 11.8±2.9 years; 4 female). All underwent a CPET and 6MWT. Peak oxygen consumption (pVO(2)) and 6MWT distance were reduced to 31.5±12.2% and 47.7±16.7% of the predicted value, respectively (p<0.0001 for both). pVO(2) and oxygen consumption at anaerobic threshold showed correlation with 6MWT distance (r=0.49; p=0.001 and r=0.40, p=0.01, respectively), while an inverse correlation was found between measures of ventilatory efficiency (eg, VE/VCO(2)) at anaerobic threshold and 6MWT distance (r=-0.43; p=0.005). There was a significant linear relationship between pVO(2) and 6MWT up to a distance of 300 m, with the 6MWT distance accounting for 71% of the variation in pVO(2) but there was hardly any association when the 6MWT distance was >300 m. CONCLUSIONS: The 6MWT reflects maximal exercise capacity in patients with a 6MWT distance below 300 m. A CPET should therefore be considered as a complimentary test in children with an exercise tolerance above this threshold. These findings may have implications for assessing response to drug therapy and for consideration as an end point in future PAH trials.

Effect of altering pathologic right ventricular loading conditions by percutaneous pulmonary valve implantation on exercise capacity.

The data describing the change in exercise capacity after surgical or interventional management of the patient with right ventricular (RV) outflow tract (OT) dysfunction are conflicting. The pathophysiologic consequences of RVOT interventions and the subsequent change in exercise performance are still poorly understood. We sought to assess the effect of percutaneous pulmonary valve implantation (PPVI) on exercise capacity in (1) patients with predominantly pulmonary stenosis (PS) and (2) in patients with predominantly pulmonary regurgitation (PR). A total of 63 patients with either predominantly PS (n = 37) or PR (n = 26) underwent PPVI. Cardiopulmonary exercise testing and magnetic resonance imaging were performed before and within 1 month after PPVI. On magnetic resonance imaging, the at rest effective biventricular stroke volumes improved in both groups after PPVI (p <0.001), but the ejection fraction improved only in the PS group. In the PS group, exercise capacity (peak oxygen uptake, p <0.001), ventilatory efficiency (p <0.001), and peak oxygen pulse (p <0.001) improved after PPVI. In the PR group, none of these parameters changed after PPVI (p = 0.6, p = 0.12, and p = 0.9, respectively). On multivariate analysis, the reduction in RVOT gradient was the only predictor of improved peak oxygen uptake when assessed in the whole patient group (r(part) = -0.59; p <0.001) or in the PS (r(part) = -0.45; p = 0.002) or PR groups alone (r(part) = -0.45; p = 0.02). In conclusion, acutely after PPVI, exercise capacity improves with the relief of stenosis but not regurgitation. A reduction in the RVOT gradient, even small gradients, was the only independent predictor of improved peak oxygen uptake in both patient groups, irrespective of improved pulmonary valve competence.

Ventilatory efficiency and aerobic capacity predict event-free survival in adults with atrial repair for complete transposition of the great arteries.

OBJECTIVES: The goal of this study was to assess the prognostic value of the cardiopulmonary exercise test (CPET) in patients who received a Mustard and Senning (M/S) operation. BACKGROUND: Patients who received an M/S operation have increased long-term risk of cardiovascular morbidity and mortality. Limited information is available on how to stratify risk in this population. METHODS: Between 1996 and 2007, 274 adults (age 26.3 +/- 8.9 years, range 16 to 50 years) who had received a Mustard (n = 144) or Senning (n = 130) operation in infancy were studied with CPET. During a follow-up of 3.9 +/- 2.3 years (range 0.2 to 10.8 years), 12 patients died at an age of 36 +/- 14 years, and 46 patients required a cardiac-related emergency (<24 h from the onset of symptom/condition) hospital admission at an age of 30 +/- 11 years. RESULTS: At multivariate Cox analysis, the slope of ventilation per unit of carbon dioxide output (VE/VCO(2) slope) (hazard ratio: 1.088, p < 0.0001) and percentage of predicted peak oxygen uptake (Vo(2)%) (hazard ratio: 0.979, p = 0.0136) were the strongest predictors of death/cardiac-related emergency hospital admission among demographic, clinical, and exercise variables. A VE/VCO(2) slope > or =35.4 (hazard ratio: 10.7, 95% confidence interval [CI]: 7.8 to 24.6), and a peak Vo(2)% < or =52.3% (hazard ratio: 3.4, 95% CI: 2.5 to 8.2) were associated with an increased 4-year risk of death/cardiac-related emergency hospital admission. Patients who had both a VE/VCO(2) slope > or =35.4 and a peak Vo(2)% < or =52.3% of predicted value were at highest risk (4-year event rate: 78.8%). CONCLUSIONS: CPET provides important prognostic information in adults with M/S operation. Subjects with enhanced ventilatory response to exercise or those with poor exercise capacity have a substantially higher 4-year risk of death/cardiac-related emergency hospital admission.