Left Ventricular Function Dynamic Alteration In A Rat Model With Coronary Microembolization And Its Assessment By Novel Echocardiographic Modalities

ObjectivesThe aim of this study was to observe the dynamic changes of ventricular systolic function in a rat model with coronary micro-embolization (CME) by simultaneously using three novel modalities of anatomical M-Mode (AME), quantitative tissue velocity imaging (QTVI), strain and strain rate imaging (SI/SRI); to explore the characteristics and the patterns of these changes of ventricular systolic function both in the acute phase and in the following chronic phases; to compare the values of the three new imaging modalities in the evaluation of ventricular systolic function after CME.MethodsWe created a rat model of CME by injecting a suspension of microthrombotic particles into left ventricle when clamping the ascending aorta. The microthrombotic particles were generated from the rat clots. Twenty-four rats were randomly divided into two groups: control group(n=8) and model group(n=16). Echocardiography by using three different imaging modalities of AME, QTVI, SI/SRI was performed at baseline, and 1-day , 2-week and 4-week after CME. The parametric measurements include systolic and diastolic thickness of regional left ventricle (WTs and WTd) and systolic thickening fraction of regional left ventricle(WTF),LVEDD,LVEDS,LVEF derived by AME, subendo, mid- subepi- and transmural myocardial tissue velocities (SPVendo, SPVmid, SPVepi and SPV) derived by QTVI, and the strain rate and strain(SR and t )derived by SI/SRI.The animals were sacrificed at 4 weeks after CME, A microscopy incorporated with an image analysis software (lmagePro-4) was employed to calculate the number of micro-myocardial infarction (Nmmi) in sections with HE-staining, to measure the fraction of collagen fiber (Fcf) in sections with Sirius-Red-staining.