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Measuring Cardiac Autonomic Nervous System (ANS) Activity in Children
Published on: April 29, 2013
Cardiac responses to progressive exercise in normal children: a synthesis
1Department of Pediatrics, Baystate Medical Center, Springfield, MA 01199, USA.
Insights
Pediatric cardiac responses to exercise mirror adult patterns, with stroke volume (SV) rising initially. Heart rate and contractility adjustments maintain SV and cardiac output during intense physical activity.
Area of Science:
- Pediatric cardiology
- Exercise physiology
Background:
- Cardiac responses to exercise involve complex interactions of diastolic filling, myocardial contractility, heart rate, and afterload.
- Understanding these responses in children is crucial for assessing cardiovascular health during physical activity.
Purpose of the Study:
- To characterize cardiac responses to maximal exercise in children using Doppler echocardiography.
- To compare exercise-induced cardiac adaptations in children with those observed in adults.
Main Methods:
- Two studies assessed stroke volume (SV), cardiac output, and heart rate during upright and semisupine cycle exercise in children.
- Doppler echocardiography and two-dimensional echocardiography were utilized to measure cardiac parameters and left ventricular dimensions.
Main Results:
- Pediatric cardiac responses to exercise align with adult patterns.
- Stroke volume demonstrated an initial rise, plateauing at mild-moderate exercise intensities.
Conclusions:
- Peripheral vasodilatation contributes to the early increase in stroke volume.
- Elevated heart rate maintains stable stroke volume and left ventricular dimensions during high workloads.
- Enhanced myocardial contractility preserves stroke volume despite a shortened systolic ejection period.
Unlabelled:
The cardiac responses to exercise are influenced by a complex interplay of changes in diastolic filling, intrinsic myocardial contractility, heart rate, and ventricular afterload.
Purpose:
To characterize these responses in children, findings are reported from two studies utilizing Doppler echocardiographic assessment of stroke volume and cardiac output during maximal upright and semisupine cycle exercise.
Methods:
In study 1, stroke volume, heart rate, and peak aortic velocity were assessed during upright cycle exercise to exhaustion in 39 sixth-grade boys. In study 2, similar methods were used to examine cardiac responses to semisupine exercise with measurement of left ventricular dimensions by two-dimensional echocardiography.
Results:
The findings support patterns similar to that previously described in adults, with an initial rise in stroke volume reaching a plateau at mild-moderate exercise intensities.
Conclusions:
The observations in these two studies also suggest 1) peripheral vasodilatation plays an important role in the early rise in stroke volume, 2) increasing heart rate acts to maintain a stable stroke volume and left ventricular diastolic dimension at high workloads, and 3) improvements in contractility serve to maintain stroke volume as the systolic ejection period shortens.
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