The Clinical Study Of Quantitative Assessment Of Viable Myocardium Using Pulsed Tissue Doppler Imaging And Strain Rate Echocardiography

OBJECTIVES The aim of this study was to evaluate whether tissue Doppler and strain rate imaging can quantify the detection of viable myocardium and assess the contractile reserve of infracted myocardium.METHODSPART 1 In 20 patients with confirmed acute myocardial infarction and 6 patients with agina, myocardial viability was assessed using low-dose(5 and 10 microg/kg body weight per min) two-dimensional dobutamine stress echocardiography (DSE) and tissue Doppler imaging were obtained at baseline and peak-dose dobutamine stress from the apical views. Peak first systolic, second systolic, isovolumic diastolic waves(S1, S2, SIVR respectively) and isovolumic systolic, systolic isovolumic diastolic time were measured at the mitral annular level of the posteroseptal wall, lateral wall, anterior wall, and inferior wall.PART 2 8 patients with confirmed acute myocardial infarction underwent dobutamine stress echocardiography (DSE). Two-dimensional imaging and tissue Doppler-derived strain rate imaging were obtained at baseline and during low-dose dobutamine stress from the apical views. All segments of the left ventricular wall were devided into normal and viable groups based on the visual interpretation. SRof Peak systolic, post systolic shortening, early diastolic and atrial systolic were measured.RESULTS:PART 1 A total of 104 segments were classified as normal, highly-viable, viable and infarct according to visual assessment. S1 > SIVRN IVST\ ET indicated no significant differences among groups at rest while S2 wave^ E/A were redsuced in ischemic myocardium (p<0.05). The increase of peak isovolumic-systolic(Sl) from rest to peak dobutamine stimulation in each group were 65+38%, 48+28%, 32+17% , 0.2+24% respectively (F=16.5 , PO.001 by ANOVA) ; peak isovolumic-systolic(S2)42 25%, 37+15%, 41+35%, 7.5 20%(F=4.4, PO.05); shortening of IVST26.7 18.6%, 37 15%, 26.7+19%, 7+28.5%, F=4.2, P<0.05. IVRT was significantly reduced in normal and viable myocardium(p<0.001by T test) while was unchanged in infarct group,but shows no different between two groups.PART 2 A total of 96 segments were classified as normal and viable according to visual assessment. SR seemed inclining to decrease and IVR.. I IVR I increase in ischemic myocardium. Percent of change of SR after dobutamine infusion were 51 105%, 81+72% in normal and viable groups; IVR -166+396%, -68 147%; I IVR I 92.6+333.2%, 15+64%. Although SR wave significantly increased in normal and viable groups(p<0.05 by T test), all other data above lack statistical significance, due to too few subjects probably.CONCLUSIONS: The change of tissue Doppler and strain rate imaging during low-dose dobutamine stimulation promises clinically feasible accurate5discrimination between different myocardial viability states.