| Popis: |
Left ventricular ejection times ( LVETs ) were obtained in a group of 20 control subjects (group 1) during maximal treadmill exercise testing, using a Bruce protocol, and in conjunction with myocardial scintigraphy. Heart rates (HRs) and LVETs were recorded during standing rest, each minute of exercise, and for eight minutes in the postexercise period. A linear regression equation was constructed and separate correction factors of 1.04 X HR + observed LVET (correlation coefficient, -.86) for the exercise period and 0.73 X HR + LVET (correlation coefficient, -.71) for the postexercise period were derived. The LVETs were also recorded in 31 subjects with positive ECGs and defects on myocardial scanning with thallous chloride TL201 (group 2) during a similar exercise protocol. Comparison of groups 1 and 2 disclosed that the former had a higher HR and shorter LVET than the latter at peak effort (consonant with the significantly longer duration of exercise achieved by the control subjects). The LVETs in group 1 remained significantly shorter than that of group 2 through the fifth minute postexercise. In the postexercise period, the LVET indexes were significantly shorter in group 1 than group 2 at 1, 3, and 5 minutes. Subjects with presumptive coronary disease (positive ECG and defects on thallium 201 scanning) not only have a decreased exercise tolerance and HR, but after exercise, their ejection times are substantially longer than in normal subjects. This may be attributed to a slower rate of ejection in patients with coronary disease when venous pooling on quiet standing after exercise delivers a smaller volume to the heart. In normal subjects, the lesser volume may be ejected more rapidly. |
