| Background and Objective: To know whether there are still some myocardial viability is crucial in deciding the further treatment after myocardial infarction. Therefore, Developing more sensitive methods to detect the myocardial viability is an important way in echocardiography. Nowadays it mainly includes 1 .to evaluate the perfusion of the myocardium with myocardial contrast echocardiography; 2.to evaluate the systolic function reserve with stress echocardiography. And dobutamine stress echocardiogra- phy is considered the standard method to evaluate the myocardial contractility reserve after myocardial infarction.Doppler Tissue imaging( DTI )is based on Doppler principles to measure velocities of myocardium in real time , so it offers a new reliable and objective method to analyze regionalmyocardial wall motion quantitatively. A lot of studies on DTI have been done and assessment of the wall motion in the patients with coronary artery disease (CAD) by DTI has been confirmed. QTVI is a new technique that deduced from DTI. And tissue velocity imaging , tissue tracking and strain are special imaging ways of QTVI.The goal is to investigate the feasibility of evaluating the global and regional systolic function of left ventricle with QTVI, to observe the characteristics of segmental myocardium and mitral annular movement in dogs with myocardial infarction, and to detect the viable myocardium in the acute infarction combined with LDDSE and QTVI.Methods: 6 anaesthetized dogs were operated to block the LCX for 4 hours to make the acute myocardial infarction model. We wrote down the DTI spectrum 3 tangent plane of the apex in longitudinal axis under basic state, myocardium infarction, 5ug/kg/min and 10 ug/kg/min of the LDDSE separately, then analyzed the Vs and Ds. Simultaneously the position and the range of the myocardial infarction area were determined with TTC stain and myocardial contrast echocardiography. The surviving myocardium can be determined by the change of QTVI which reflects the myocardial contractility reserve, compared with TTC stain and myocardial contrast echocardiography. The diagnostic standard of surviving myocardium was made up of three points: 1, the systolic function of the segments, which were unusual demonstrated by QTVI in resting state, it was enhanced with the LDDSE. 2,Demonstrated by myocardial contrast echocardiography, the perfusion of the myocardium existed. 3, The myocardium was stained light red by TTC.Results: 1. Finding the characteristics of the left ventricle local contraction with acute myocardial infarction by QTVI The normal myocardium present three highest peak wave forms along heart major axis speed curve at basic state, The myocardium displacement curve takes the form of parabola, and reach the peak value at the end of contraction. Vs and Ds of different segment in the same ventricle demonstrate the lowering trend from the base to the apex of the heart. However, the myocardium speed curve is unusual in the acute infarction compared with the basic state and the peak of displacement curve is backward. The Vs and Ds of the left ventricle demonstrated reduction in various degrees in the acute myocardial infraction(p<0.01). Furthermore, the good correlation was found between Ds and Vs (r=0.93, p<0.01 in basic state; r=0.89, p<0.01 in myocardial infarction).2. Combined use of QTVI and Dobutamine Stress Echo(DSE) to evaluate the surviving myocardium of the acute myocardial infarction When the acute myocardial infarction occurred, both Ds and Vs were improved in different degrees after LDDSE, compared to the resting state. The changes of Vs and Ds in the surviving myocardium segments were significant in statistics (p<0.01), no change found in Vs and Ds in the segments of myocardium infarction(p>0.05) .When we use AVs>0.67cm/s as a threshold to determine whether themyocardium survive or not, the sensitivity is 83% and the peculiarity is 87%.However, when the standard comes to ADs>0.61mm, sensitivity is 80% and peculiarity is 89%.3. To evaluate the ef...
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