The Experimental Research On Safety Of Myocardial Contrast Echocardiography

Objective：To evaluate the myocardium damage of myocardial contrastechocardiography(MCE) and the impact on regional left ventricularmechanics by imaging and pathology techniques.Methods：Eleven open-chest animal models of Beagle were employedto collect the short-axis views of mitral annular，papillary muscle andapical level during three complete cardiac cycles using gray-scale imagingat the baseline and blank irradiation5mins later(transmitting frequency1.7/3.4MHz，mechanical index1.0). After that,5ml of SonoVue was gottena shot by intravenous bolus injection, the heart was radiation by ultrasonicwave for5mins continuously，and then the same images collected were atthe point-in-time irradiation immediately，20mins，40mins and60minslater. The short-axis circumferential strain and strain rate，radial strain andstrain rate were measured and calculated by Echo PAC multi-parameterworkstation, meanwhile including conventional of cardiac function. All thedogs were killed after the experiments and the specimen of myocardiumwas harvested for HE staining and observed with transmission electronmicroscope for tissue microstructure observation.Results：①Conventional parameters of cardiac function：there wasno significant difference of the heart rate, blood pressure, ejection fraction,left ventricular end-systolic volume and end-diastolic volume strokevolume, cardiac output, mitral flow spectrum prior to the E/A, tissue Doppler mitral annular e/a and E/e before and after MCE(p>0.05). Duringthe whole process of experiments, the dogs’ vital signs were stable.②Compared the segmental circumferential strain and strain rate, radial strainand strain rate between baseline and each treatment groups, theseparameters had a trend of increase in most segments, but the difference wasnot statistically significant in most segments(p>0.05).③With HE staining,the light microscope demonstrated a small amount of myocardial cellinfiltration of inflammatory cells near the outer membrane (21.2%), andvery few part of the myocardial fibers dissolved and fractured(6.1%).④The slices of transmission electron microscope showed all themicro-structures were normal except that a small amount of endothelialcells mild swelling, and some erythrocyte were leaked, some myofilamentsregional dissolved, the relevance ratio were28.6%,42.9%and21.4%respectively, and the abnormal area was less than10%of the entire field ofvision.Conclusion： MCE has no significant impact on the global or theregional ventricular mechanics, even with mild pathological damage on themyocardium.