Detecting abnormalities in left ventricular function during exercise by respiratory measurement
- Tokyo Medical and Dental Univ. (Japan)
The degree of exercise-induced cardiac dysfunction and its relation to the anaerobic threshold were evaluated in 23 patients with chronic heart disease. A symptom-limited exercise test was performed with a cycle ergometer with work rate increased by 1 W every 6 seconds. Left ventricular function, as reflected by ejection fraction, was continuously monitored with a computerized cadmium telluride detector after the intravenous injection of technetium-labeled red blood cells. The anaerobic threshold (mean, 727 {plus minus} 166 ml/min) was determined by the noninvasive measurement of respiratory gas exchange. As work rate rose, the left ventricular ejection fraction increased but reached a peak value at the anaerobic threshold and then fell below resting levels. Ejection fraction at rest, anaerobic threshold, and peak exercise were 41.4 {plus minus} 11.3%, 46.5 {plus minus} 12.0%, and 37.2 {plus minus} 11.0%, respectively. Stroke volume also increased from rest (54.6 {plus minus} 17.0 ml/beat) to the point of the anaerobic threshold (65.0 {plus minus} 21.2 ml/beat) and then decreased at peak exercise (52.4 {plus minus} 18.7 ml/beat). The slope of the plot of cardiac output versus work rate decreased above the anaerobic threshold. The anaerobic threshold occurred at the work rate above which left ventricular function decreased during exercise. Accurate determination of the anaerobic threshold provides an objective, noninvasive measure of the oxygen uptake above which exercise-induced deterioration in left ventricular function occurs in patients with chronic heart disease.
- OSTI ID:
- 6983830
- Journal Information:
- Circulation; (USA), Vol. 80:6; ISSN 0009-7322
- Country of Publication:
- United States
- Language:
- English
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CARDIOVASCULAR DISEASES
DIAGNOSIS
HEART
DYNAMIC FUNCTION STUDIES
ELECTROCARDIOGRAMS
ERYTHROCYTES
EXERCISE
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TECHNETIUM ISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
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BODY FLUIDS
CARDIOVASCULAR SYSTEM
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ORGANS
550601* - Medicine- Unsealed Radionuclides in Diagnostics