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Cardiopulmonary Fitness in Children With Congenital Heart Disease
Study Questions:
What is the relationship between cardiopulmonary fitness of children with congenital heart diseases (CHD) and age- and gender-adjusted controls? And, what are the clinical characteristics associated with maximum oxygen uptake (VO2max) in pediatric CHD?
Methods:
The authors conducted a cross-sectional multicenter study of 798 children (496 CHD and 302 controls) who underwent a complete cardiopulmonary exercise test (CPET) with a pediatric cycle ergometer and protocol adapted for CHD. The design was intended to provide a homogeneous incremental overall duration between 8 and 12 minutes: a 1-minute rest; a 3-minute warm-up (10–20 W) in increments of 10, 15, or 20 W each minute; a pedaling rate of 60–80 revolutions per minute; a 3-minute active recovery (20 W); and a 2-minute rest. VO2max was defined as an adult CPET with three of the following: maximal effort tolerance, >85% of max age-predicted heart rate, respiratory exchange ratio ≥1.1, and plateau VO2 with increasing workload. The association of clinical characteristics with VO2max was studied using a multivariate analysis.
Results:
Mean age was 12.2 years in the CHD group and 11.1 years in controls (p < 0.001) with no difference in biometrics. Mean VO2max in the CHD group and controls represented 93% ± 20% and 107% ± 17% of predicted values, respectively. VO2max was significantly lower in the CHD group, overall (37.8 ± 0.3 vs. 42.6 ± 0.4 ml/kg/min, (p < 0.0001) and for each group (p < 0.05). The mean VO2max decline per year was significantly higher in the CHD group than in the controls overall (−0.84 ± 0.10 vs. −0.19 ± 0.14 ml/kg/min/yr, p < 0.01), for boys (−0.72 ± 0.14 vs. 0.11 ± 0.19 ml/kg/min/yr, p < 0.01), and for girls (−1.00 ± 0.13 vs. −0.55 ± 0.21 ml/kg/min/yr, p = 0.05). VO2max was associated with body mass index, ventilatory anaerobic threshold, female gender, restrictive ventilatory disorder, right ventricle systolic hypertension, tricuspid regurgitation, the number of cardiac catheter or surgery procedures, and the presence of a genetic anomaly.
Conclusions:
Although the magnitude of the difference was not large, VO2max among children with CHD was significantly lower than in normal children. The authors suggest that CPET should be considered for routine follow-up of these patients.
Perspective:
In adults with heart failure and CHD, measured VO2max correlates with both quality of life and prognosis, and CPET has become the ‘gold standard.’ While ‘routine’ follow-up may be costly, the authors also suggest that in pediatric CHD, most studies will be normal, which may contribute to less parental worry and promote physical activity in these young patients. Also, studies are needed to determine whether VO2max change with age should be a main parameter to identify children with CHD who are eligible for cardiac rehabilitation.
Keywords: Anaerobic Threshold, Body Mass Index, Cardiac Catheterization, Cardiac Rehabilitation, Cardiac Surgical Procedures, Exercise, Exercise Test, Heart Defects, Congenital, Heart Rate, Hypertension, Pediatrics, Quality of Life, Tricuspid Valve Insufficiency, Workload
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