Echocardiographic analysis of dysfunctional and normal myocardial segments before and immediately after coronary artery bypass graft surgery
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Coronary artery bypass graft (CABG) surgery improved function in some heart muscle segments, while others showed reduced function. Systolic wall thickening is a more reliable echocardiographic measure post-CABG than wall motion analysis.
Area of Science:
- Cardiology
- Cardiac Surgery
- Diagnostic Imaging
Background:
- Myocardial ischemia can cause subnormal contraction and hyperkinetic regions.
- The impact of coronary artery bypass graft (CABG) surgery on these regions is not well understood in humans.
Purpose of the Study:
- To evaluate changes in segmental wall motion and systolic wall thickening immediately after CABG surgery.
- To compare the reliability of echocardiographic assessments of myocardial function post-CABG.
Main Methods:
- Echocardiography was used to assess 256 myocardial segments in 32 patients before and immediately after CABG surgery.
- Analysis included segmental wall motion and percent of systolic wall thickening.
Main Results:
- 66% of segments showed subnormal function pre-CABG; 67% improved and 60% normalized post-CABG.
- Hyperkinetic segments normalized post-CABG.
- Systolic wall thickening increased in segments <30% pre-CABG and decreased in segments >30% pre-CABG (P<0.01).
Conclusions:
- CABG surgery leads to functional recovery in some myocardial segments and reduced function in others.
- Percent of systolic wall thickening is a more reliable echocardiographic index than segmental wall motion for assessing myocardial function immediately after CABG.
Abstract:
Echocardiography has revealed evidence of "subnormal" regional contraction patterns that result from myocardial ischemia and are often accompanied by nonadjacent "hyperkinetic" regions. Whether these regions of hyperkinetic wall motion persist unchanged or revert to normal after coronary artery bypass graft (CABG) surgery has not been studied in humans. Using echocardiography, we evaluated both dysfunctional and normal myocardial regions for changes in segmental wall motion and percent of systolic wall thickening that occurred immediately after CABG surgery in 32 patients. Segmental wall motion analysis before CABG surgery in these patients revealed that 170 (66%) of 256 myocardial segments were subnormal, of which 115 (67%) improved and 102 (60%) returned to normal immediately after CABG surgery. Eleven myocardial segments that were hyperkinetic before CABG surgery returned to normal after CABG surgery. Preoperatively, 162 (63%) of 256 myocardial segments had systolic wall thickening less than 30%, which increased from 11.8% +/- 8.9% to 24.3% +/- 14.3% (mean +/- SD) (P less than 0.01) postoperatively. Conversely, a reverse trend was found when systolic wall thickening was greater than 30% before CABG surgery: thickening decreased from 46.2% +/- 13.8% to 33.4% +/- 14.8% after CABG surgery (P less than 0.01). Thus, we conclude that immediately after CABG surgery, there is a recovery of function in some myocardial segments and a reduction in function in others. Furthermore, we conclude that the semiquantitative assessment of percent of systolic wall thickening is a more reliable (consistent) echocardiographic index of myocardial function compared with the qualitative assessment of segmental wall motion immediately after CABG surgery.