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Cardiac function and exercise capacity of diabetic patients
S Uchimoto1, K Tsumura, N Yamashita
1Second Department of Internal Medicine, Osaka City University Medical School, Japan.
Journal of Nutritional Science and Vitaminology
|December 1, 1991
Summary
Diabetic patients with impaired cardiac diastolic function (longer isovolumic relaxation time) have reduced exercise capacity. Non-invasive measures like isovolumic relaxation time can predict cardiovascular response to exercise in diabetics.
Area of Science:
- Cardiology
- Diabetology
- Exercise Physiology
Background:
- Type 2 diabetes mellitus is associated with cardiovascular complications.
- Diabetic patients often exhibit impaired cardiac function, affecting exercise capacity.
Purpose of the Study:
- To investigate the relationship between resting cardiac function and exercise capacity in non-insulin-dependent diabetic patients.
- To determine if left ventricular diastolic function and cardiac autonomic reflexes influence exercise performance.
Main Methods:
- Evaluated 15 male diabetic patients using simultaneous echophonocardiograms, electrocardiograms, and carotid pulse recordings.
- Measured isovolumic relaxation time (IRT) and PEP/LVET ratio at rest.
- Assessed exercise capacity via VO2 at anaerobic threshold using cycle ergometry and expired gas analysis.
Main Results:
- Patients with longer IRT (>= 90 msec) showed significantly lower VO2 at anaerobic threshold compared to those with shorter IRT (< 90 msec).
- A strong correlation was found between IRT and the change in heart rate (delta HR) from rest to anaerobic threshold (r=0.666, p<0.01).
- VO2 at anaerobic threshold correlated well with both IRT (r=0.555, p<0.05) and delta HR (r=0.858, p<0.01).
Conclusions:
- Resting left ventricular diastolic function, assessed by IRT, impacts exercise capacity in diabetic patients.
- Cardiac sympathetic nervous system reflexes, indicated by delta HR, also play a role in exercise limitation.
- IRT is a potentially useful non-invasive index for evaluating cardiovascular response to exercise in diabetic patients without coronary artery disease.