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Ventilatory anaerobic threshold for evaluating exercise performance in children with congenital left-to-right
Insights
Children with congenital heart disease (CHD) show a lower ventilatory anaerobic threshold (VAT) during exercise compared to healthy peers. VAT is a more sensitive indicator of reduced cardiorespiratory endurance in these children than VO2,170.
Area of Science:
- Pediatric Cardiology
- Exercise Physiology
- Cardiorespiratory Fitness
Background:
- Congenital heart disease (CHD) affects cardiorespiratory function during exercise.
- Assessing exercise capacity in children with CHD is crucial for management.
- The ventilatory anaerobic threshold (VAT) is a physiological marker of exercise intensity.
Purpose of the Study:
- To evaluate the ventilatory response to graded treadmill exercise in children with CHD and a left-to-right shunt.
- To compare exercise parameters, specifically VAT and VO2,170, between children with CHD and healthy controls.
- To determine the sensitivity of VAT versus VO2,170 in detecting reduced exercise capacity in pediatric CHD.
Main Methods:
- Studied 50 children with CHD (left-to-right shunt) and age/sex-matched healthy children.
- Utilized graded treadmill exercise to measure minute ventilation (VE) and oxygen uptake (VO2).
- Identified the ventilatory anaerobic threshold (VAT) and VO2 at a heart rate of 170/min (VO2,170).
Main Results:
- A ventilatory anaerobic threshold (VAT) was detected in all children.
- Children with CHD showed a significantly higher percentage of subnormal VAT (56%) compared to VO2,170 (28%).
- Mean VAT was significantly lower (89% of normal) than mean VO2,170 (103% of normal) in the CHD group.
Conclusions:
- Ventilatory anaerobic threshold (VAT) is a sensitive, noninvasive criterion for evaluating exercise performance in children with CHD and left-to-right shunts.
- VAT is more sensitive than VO2,170 in detecting decreased cardiorespiratory endurance capacity in this pediatric population.
- Findings highlight the utility of VAT in clinical assessment of exercise limitations in pediatric CHD.
Abstract:
The ventilatory response to graded treadmill exercise was studied in 50 children with congenital heart disease (CHD), a left-to-right intracardiac shunt, and compared to that of age and sex-matched healthy children. In all these children, a breakpoint in the minute ventilation (VE) in relation to increasing oxygen uptake (VO2) was detected. Because of the reported coincidence of the nonlinear increase in VE and lactate with increasing VO2, this threshold has been named "ventilatory anaerobic threshold" (VAT), expressed in ml O2 X min-1 X kg-1. VAT correlated well with VO2 (ml X min-1 X kg-1), reached at a heart rate of 170/min (VO2,170). Compared to normal children, however, a significantly (p less than 0.05) larger percentage (56%) of the patients showed a subnormal value (below the 95% confidence limit) for VAT than for VO2,170 (28%). Furthermore, when expressed as a percentage of the mean normal value, the mean VAT (89 +/- 14.4% SD) was significantly (p less than 0.05) lower than the mean VO2,170 (103 +/- 17.2%). VAT (ml O2 X min-1) correlated significantly with body weight and height, even after adjusting for age, and with the percentiles of body weight and height. VAT constitutes a useful noninvasive criterion for evaluating exercise performance in children with CHD, at least those forms with a left-to-right intracardiac shunt, and it is significantly more sensitive than the VO2,170 in detecting decreased cardiorespiratory endurance capacity.