Experimental research on safety of myocardial contrast echocardiography / 中华超声影像学杂志

ABSTRACT

ObjectiveTo evaluate the myocardium damage of myocardial contrast echocardiography (MCE) and the impact on regional left ventricular mechanics by imaging and pathology techniques.Methods Eleven open-chest animal models of Beagle were employed to collect the short-axis views of mitral annular,papillary muscle and apical level of three complete cardiac cycles using gray-scale imaging at the baseline and blank irradiation 5 min later(transmitting frequency 1.7/3.4 M Hz,mechanical index 1.0).After that,5 ml of SonoVue was gotten a shot by intravenous bolus injection,the heart was exposed by ultrasonic wave for 5 min continuously,and then the same images collected were at the point-in-time irradiation immediately,20 min,40 min and 60 min later.The short-axis circumferential strain and strain rate,radial strain and strain rate were measured and calculated by EchoPAC multi-parameter workstation,meanwhile including conventional of cardiac function.All the dogs were killed after the experiments and the myocardium was harvested for HE staining and observed with transmission electron microscope for the tissue microstructure.Results①Conventional parameters of cardiac functionthere was no significant difference before and after MCE in the heart rate,blood pressure,ejection fraction,left ventricular end-systolic volume and end-diastolic volume,stroke volume,cardiac output,mitral flow spectrum prior to the E/A,tissue Doppler mitral annular e/a and E/e ( P ＞0.05).During the whole process of experiment,the dogs’ vital signs were stable.②Compared the segmental circumferential strain and strain rate,radial strain and strain rate between baseline and each treatment groups,these parameters had a trend of increase in most segments,but the difference was not statistically significant in most segments (P ＞0.05).③HE staining at the light microscope demonstrated a small amount of myocardial cell infiltration of inflammatory cells near the outer membrane (21.2％),and very few part of the muscle fibers dissolved and fractured (6.1％).④The section of transmission electron microscope showed all the structures were normal except that a small amount of endothelial cells were mild swelling,some red blood cells were leaked,some myofilaments were regional dissolved,the relevance ratio were 28.6 ％,42.9 ％ and 21.4 ％ respectively,and the abnormal area was less than 10％ of the entire field of vision.ConclusionsMCE has no significant impact for the global function of heart and the regional mechanical state,and furthermore there is no serious pathological damage on the myocardium.