[Effects of repetitive myocardial ischemia on collateral circulation, ST deviation and epicardial wall motion].

The effects of repetitive myocardial ischemia on collateral circulation, ST deviation and epicardial wall motion were examined in 12 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) for single left anterior descending artery disease. Rentrop collateral filling grade was assessed using contrast injection to the contralateral artery during the first and final episodes of coronary occlusion. ST deviation was measured by intracoronary electrocardiography. Epicardial wall motion (%pre PTCA) was measured by guide wire motion analysis according to the centerline method. Collateral filling grade was assessed 30 sec after balloon inflation. The ST segment and the epicardial wall motion were measured 60 sec after balloon inflation and deflation, respectively. There was no change in the collateral filling grade between the first and final episode of coronary occlusion. Patients with collateral filling grade I (R-I group, n = 4), II (R-II group, n = 3) and III (R-III group, n = 5) during coronary occlusion showed mean ST segment shifts of 13.2, 9.4, and 0.9 mm, respectively, and mean epicardial wall motion of 41.4%, 67.2%, and 78.5%, respectively. The collateral filling grade correlated with ST deviation and epicardial wall motion, and there was a significant correlation between epicardial wall motion and ST deviation (r = -0.67). Comparison of the R-I group or severe ischemia (n = 4) and the R-III group or slight ischemia (n = 4) during coronary occlusion for the fourth time showed the effect of preconditioning was obtained in R-I group. More R-III group patients than R-I group had hyperkinetic epicardial wall motion during coronary reperfusion. Stunned myocardium was demonstrated in both R-I group and R-III group patients. Epicardial wall motion was poorer in the R-I group than R-III group. We concluded the following: There is no change in the grade of collaterals during repetitive coronary occlusion, and there is a relationship between the grade of collateral and degree of myocardial protection; there is good correlation between ST segment and epicardial wall motion; ischemic preconditioning is obtained during repetitive severe myocardial ischemia; recovery from brief episodes of slight myocardial ischemia is associated with hyperkinesia of epicardial wall motion; the reduction of stunned myocardium is related to the degree of premyocardial ischemia; preconditioning is sufficient to cause myocardial stunning, but myocardial stunning is insufficient to cause preconditioning.