Real time assessment of myocardial revascularization during coronary artery bypass surgery by means of ultrasonic integrated backscatter

Objective: The recovery of cyclic variation (CV) of ultrasonic integrated b ackscatter (IB) may provide a more sensitive predictor of the success of my ocardial revascularization. This study was designed to elucidate the possib ility of real time assessment of coronary artery bypass grafting (CABG) usi ng CV of IB. Methods: We studied 10 patients (61 +/- 4 years old) with the perfused areas by stenosed or occluded LAD without myocardial infarction. T here were six ischemic dysfunctional areas, and four ischemic but non-dysfu nctional areas. The CV of LB was measured before and just after extracorpor eal circulation (ECC). Wall motion was analyzed by segmental wall thickenin g during systole at the same time of the IB analysis during CABG and at 3 w eeks after CABG. Those 10 areas were completely revascularized. Results: In the non-dysfunctional areas, wall thickening did not change and remained a t normal values before and after ECC, and 3 weeks after CABG (31 +/- 3% 29 +/- 3% and 29 +/- 5%, respectively). The magnitude of CV of IB did not also change before and after ECC (8.0 +/- 1.6 dB and 7.8 +/- 1.3 dB). However, in the ischemic dysfunctional areas, while wall thickening did not change b efore and after ECC (21 +/- 58 and 20 +/- 5%), it increased and reached sim ilar values as the non-dysfunctional regions at 3 weeks after CABG (26 +/- 7%, P < 0.01 vs. before and after ECC values). The magnitude of CV of IB in creased even after ECC (3.71 +/- 0.4 dB vs. 7.4 +/- 3.5 dB, P < 0.05), and reached the same level as those in the non-dysfunctional areas. There was a significant relationship between wall thickening at 3 weeks after bypass g rafting and magnitude of CV of IB after ECC (r = 0.67, P < 0.05). Conclusio ns: Improvement in wall motion was gradually attained after bypass grafting . On the contrary, an increase in the magnitude of CV of IB was obtained im mediately after myocardial revascularization. Our data suggest that CV of u ltrasonic IB method can provide close real time information regarding the e ffectiveness of bypass surgery. (C) 1999 Elsevier Science B.V. All rights r eserved.