Quantitative Evaluation Of Coronary Microcirculation In Pigs After Acute Myocardial Infarction By Myocardial Contrast Echocardiography And Low Mechanical Index Real-time Ultrasound Imaging

Objective To evaluate the accuracy and reliability of low mechanical index real-time echocardiography in quantitative evaluation of regional myocardial blood flow and coronary flow reserve.Methods A model of acute myocardial infarction reperfusion in Panama miniature pigs was established.Myocardial contrast echocardiography was performed at rest and load state.The dynamic image of local myocardial refilling was obtained by real-time echocardiography with low mechanical index.A curve describing the acoustic intensity of the contrast medium in the filling process was obtained by analyzing the image processing software.The curve can be fitted by formula y = A [1-e(-beta t)].Among them,A is the loudest intensity,representing myocardial capillary density,and beta is filling rate,representing blood flow velocity.The product of A beta and A beta is local myocardial blood flow.Quantitative measurement of reperfusion area of acute myocardial infarction in pigs was performed to obtain myocardial blood flow in reperfusion area of acute myocardial infarction in two states of rest and load,and coronary flow reserve was calculated.By comparing the results obtained by this method with those obtained by positron emission tomography(gold standard),we can make a rough judgement of the accuracy and reliability of this method.Results The two methods are highly correlated in quantitative regional myocardial blood flow(r = 0.93,P < 0.05);the two methods are well correlated in quantitative coronary blood flow reserve(r = 0.86,P = 0.002);the perfusion defect area determined by myocardial contrast echocardiography is consistent with the myocardial infarction reperfusion area determined by pathological staining.The perfusion defect area measured quantitatively by myocardial contrast echocardiography is infarction.The myocardial blood flow in the dead reperfusion area was lower than that in the normal area,and the difference was statistically significant by paired t-test(t=-9.17,P < 0.05).Conclusions The results of the above statistical analysis show that myocardial contrast echocardiography is feasible in quantitative measurement of regional myocardial blood flow and coronary flow reserve,because the results are highly correlated with the "gold standard",indicating that it has the potential for accurate quantitative measurement of the above two parameters.In addition,the value of regional myocardial blood flow quantitatively measured by myocardial contrast echocardiography is different in the infarction reperfusion area and normal area,which indicates that the method can also distinguish normal and ischemic myocardium by quantifying regional myocardial blood flow.