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Changes in plasma catecholamine concentrations in patients with coronary heart disease during pacing and physical
Insights
Physical exercise, not atrial pacing, significantly increases plasma catecholamines in coronary heart disease patients. Atrial pacing does not adequately stimulate cardiac sympathetic tone.
Area of Science:
- Cardiology
- Neuroscience
- Exercise Physiology
Background:
- Coronary heart disease (CHD) is associated with altered sympathetic nervous system activity.
- Understanding sympathetic responses during different stressors is crucial for managing CHD.
Purpose of the Study:
- To compare sympathetic nervous system activation during right atrial pacing versus physical exercise in CHD patients.
- To investigate the release of catecholamines from the myocardium during these interventions.
Main Methods:
- Investigated plasma catecholamine concentrations (noradrenaline, adrenaline) in the coronary sinus and brachial artery.
- Utilized radioenzymatic assay in 11 male patients with documented coronary artery disease.
- Gradually increased heart rate via atrial pacing and workload via bicycle ergometry.
Main Results:
- Plasma noradrenaline and adrenaline levels significantly increased only during physical exercise.
- A greater arterial-coronary sinus noradrenaline difference was observed during exercise, indicating myocardial release.
- Atrial pacing did not induce a significant increase in catecholamines or myocardial release.
Conclusions:
- Physical exercise effectively enhances cardiac and peripheral sympathetic tone in CHD patients.
- Right atrial pacing is insufficient to elicit a comprehensive sympathetic response in this population.
- Findings suggest differential sympathetic activation patterns based on the type of stressor in CHD.
Abstract:
To study the difference in sympathetic activity during pacing the right atrium or during physical exercise in patients with coronary heart disease, we investigated circulating plasma catecholamine concentrations in the coronary sinus and brachial artery radioenzymatically in 11 male patients with well documented coronary artery disease. Heart rate was increased stepwise 20 beats/min from 90 beats/min up to 150 beats/min by pacing the right atrium and physical exercise was performed by increasing work load stepwise by 25 from 25 up to 100 W on an ergometric bicycle. Plasma noradrenaline and adrenaline concentrations were increased significantly only during physical exercise. In addition, there was an increase in arterial-coronary sinus noradrenaline difference during graded physical exercise, whereas no further release of noradrenaline from the myocardium occurred during pacing. An enhanced cardiac sympathetic tone in patients with coronary heart disease is discussed. It is suggested that atrial pacing is not an adequate stimulus evoking an overall increase of cardiac and peripheral sympathetic tone.