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Diastolic time during static and dynamic exercise in myocardial infarction
T Hasegawa1, T Sugiura, M Matsutani
1Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Chest
|September 1, 1990
Summary
Dynamic exercise significantly shortens diastolic time (DT) in myocardial infarction patients, potentially causing oxygen supply-demand imbalance. Static exercise, however, did not show this DT shortening effect.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Understanding cardiac response to different exercise types is crucial for patients with myocardial infarction.
- Left ventricular ejection time (DT) and heart rate (HR) are key indicators of cardiac function during exercise.
Purpose of the Study:
- To compare the effects of static versus dynamic exercise on DT in myocardial infarction patients.
- To investigate the relationship between DT and HR during early-phase exercise in this population.
Main Methods:
- Ear densitography was used to measure DT in 11 myocardial infarction patients.
- Patients underwent both static (sustained weight load) and dynamic (treadmill) exercise protocols.
- Electrocardiographic monitoring ensured no ischemic responses occurred.
Main Results:
- Both exercise types increased HR and pressure-HR product, but dynamic exercise showed a significantly higher pressure-HR product.
- Dynamic exercise led to a significant lengthening of left ventricular ejection time and a significant prolongation of QS2, shortening DT (p < 0.05).
- Static exercise caused a significant rise in diastolic blood pressure, unlike dynamic exercise.
Conclusions:
- Dynamic exercise, compared to static, results in a disproportionate shortening of diastole in the early phase.
- This diastolic time shortening during dynamic exercise may increase the risk of myocardial oxygen supply-demand imbalance in patients with myocardial infarction.