Experimental study of relationship on myocardial perfusion, regional contractile function and cell apoptosis in stunned myocardium by myocardial contrast echocardiography with computer-aided technique / 中华超声影像学杂志

ABSTRACT

Objective To evaluate a new computer-aided technique applicable for myocardial contrast echocardiography(MCE) to quantitate automatically calibrated myocardial contrast intensity(CD and to test the feasibility of calibrated CI in assessing myocardial perfusion. To analyze the relationship on myocardial perfusion,regional contractile function and cell apoptosis in stunned myocardium. Methods According to coronary occlusion and reperfusion at different times, rabbits were divided into three groups 15 min occlusion/30min reperfusion (group Ⅰ ),30 min occlusion / 60min reperfusion (group Ⅱ ) and 120 min occlusion / 60min reperfusion (group Ⅲ ). MCE was performed on all rabbits at baseline,occlusion and after reperfusion,and its images were analyzed by a new computer-aided technique. Myocardial calibrated CI of each segment was measured automatically by software. Percentage wall thickening (WT) of each risk segment at each stage were also measured by echocardiography. The apoptotic index(AI) in regional left myocardial dysfunction was calculated by terminal deoxynucleotidyl transferease-mediated biotinylated deoxyuridine triphosphate nick end labeling(TUNEL ). Results (1) During occlusion, WT in the areas at risk decreased to zero or negative and the calibrated CI values were significantly lower than those at baseline ( P ＜0.01 ). After reperfusion, WT in all risk segment remained depressed, but calibrated CI significantly improved in group Ⅰ and Ⅱ while those remained unchanged in group Ⅲ. (2)AI in risk myocytes were (13. 70 ± 5.48 ) %, (36.25 ± 5.55 ) % and ( 62.06 ± 6. 70 ) %, respectively, both statistically significant difference between the two groups ( P ＜0.05 or P ＜ 0.01 ). AI were negatively correlated to WT and calibrated CI ( r = - 0. 87 and r = - 0. 77, P ＜0.05). Conclusions MCE with computer-aided technique can assess quantitatively myocardial perfusion and regional contractile function. Short-term ischemiareperfusion does not cause myocardial necrosis, but it will lead to myocardial cell apoptosis and the phenomenon of myocardial stunning. Prolonged ischemia, even if given sufficient reperfusion, can lead to apoptosis and necrosis simultaneously.