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Effect of coronary artery bypass grafting on left ventricular response to isometric exercise
Insights
Coronary artery bypass grafting improves left ventricular function during isometric exercise in patients with open grafts. However, patients with blocked grafts do not show improved left ventricular response to exercise.
Area of Science:
- Cardiovascular Surgery
- Cardiac Physiology
- Exercise Cardiology
Background:
- Assessing left ventricular (LV) function during stress is crucial after coronary artery bypass grafting (CABG).
- Isometric handgrip exercise is a valuable tool for evaluating cardiac response to stress.
Purpose of the Study:
- To evaluate the impact of CABG on the left ventricular response to isometric handgrip exercise.
- To compare the LV response in patients with patent grafts versus those with occluded grafts.
Main Methods:
- 20 patients underwent handgrip exercise tests preoperatively and 3 months post-CABG.
- Left ventricular ejection fraction (LVEF) and the ratio of peak systolic pressure to end-systolic volume index (PSP/ESVI) were measured.
Main Results:
- Preoperatively, LVEF decreased during handgrip exercise (0.57 to 0.49, p<0.001).
- Postoperatively, patients with patent grafts showed no change in LVEF but an increased PSP/ESVI ratio during exercise (4.5 to 5.6, p<0.001).
- Patients with occluded grafts showed a decreased LVEF postoperatively (0.56 to 0.48, p<0.02) and no change in PSP/ESVI during exercise.
Conclusions:
- CABG improves LV response to isometric exercise in patients with patent grafts.
- The benefits of CABG on LV exercise response are not observed in patients with occluded grafts.
Abstract:
The left ventricular (LV) response to isometric exercise was evaluated in 20 patients who performed handgrip exercise tests before and 3 months after coronary artery bypass grafting. Preoperative LV ejection fraction (EF) decreased during the handgrip test from 0.57 +/- 0.08 to 0.49 +/- 0.09 (p less than 0.001); the ratio between the LV peak systolic pressure (PSP) and end-systolic volume index (ESVI) did not change. In 12 patients with patent grafts, the LVEF after operation did not change (0.54 +/- 0.06 at rest and 0.56 +/- 0.06 during handgrip exercise) and PSP/ESVI ratio increased from 4.5 +/- 1.5 to 5.6 +/- 2.1 mm Hg/ml X m-2 (p less than 0.001) during exercise. In 8 patients with occluded grafts, the LVEF after operation decreased from 0.56 +/- 0.10 to 0.48 +/- 0.06 (p less than 0.02), whereas PSP/ESVI did not change during handgrip exercise. Thus, the LV response to isometric handgrip exercise appears to improve after coronary artery bypass grafting in patients with patent grafts, but not in patients with 1 or more occluded grafts.