The Impact Of Dobutamine On Left Ventricular Systolic And Diastolic Synchronism: Assessment By Tissue Doppler Imaging

objective: This study evaluated the effect of dobutamine on patients with ischemic cardiomyopathy(ICM) by tissue Doppler imaging(TDI). To investigate whether low dose dobutamine(2-10μg/kg min)could improve left ventricular systolic and diastolic synchronism and diastolic function.Methods: Fifteen patients with ICM(sinus rhythm, QRS≤120ms); Fifteen patients with acute myocardial infarction(AMI) and Fifteen age-matched healthy individuals. Intravenous dobutamine was infused with pump in two groups patients(5,10μg/kg min).Transthoracic echocardiograms was recorded with the use of a HP Sonos 5500 color echocardiographic diagnostic system with tissue Doppler imaging. At rest and each stages of dobutamine infusion ,figures were recorded using 2-dimentional guide M-mode ,pulse wave and TDI. We acquired eject fraction(EF) and left ventricular diastolic end diameter(LVDED),left ventricular systolic diameter(LVSED),the peak early diastolic velocity(Ev), the atrial systolic wall motion velocity(Av),Ev/Av, isovolumic relaxtion time(IVRT).E peak deceleration time(EDT).ECG and phonocardiogram were recorded by synchronization. From the echocardiography apical 4-chamber and 2-chamber views, the activities in the mitral annulus (anterior, posterior, septal ;lateral) were recorded by TDI. We measured the peak systolic velocity(S),the peak early diastolic velocity(E) and the atrial systolic wall motion velocity(A).We calculated the means of S,E,A(Sm,Em,Am).Systolic electromechanical dispersion(Tcds) is the time from the electrocardiographic Q or R wave to the peak of systolic wave. Diastolic electromechanical dispersion(Tcde) is the time from the second heart sound to the peak of early diastolic velocity. Severity of systolic and diastolic asynchrony were assessed by the maximal difference of the four sides in Tcds and Tcde.Results:1.At the rest ,there was significant difference in Tcds and Tcde among the three groups(P<0.001,P<0.01). Tcds and Tcde were observed to be longer in the patients groups than in controls(P<0.05).2.In the pearson correlation model, EF, Sm, Em, LVDED significantly correlated with Tcds(P<0.05).correlation coefficient R=-0.78, R=-0.60, R=-0.40, R=0.70。Sm, Em significantly correlated with Tcde(P<0.05). correlation coefficient R=-0.49,R=-0.61。3.ICM was observed the result in the rest,5μg/kg min,10μg/kg min: Sm and EF increased with dobutamie dose increasing, but only 10μg/kg min Sm showed statistical difference comparing with other doses.Conclusion:1.TDI is more sensitive and accurate in evaluating ventricular synchronism.2.The normal QRS(QRS≤120ms) in ICM shows significant systolic and diastolic asynchronism.3.Sm is more sensitive than EF in evaluating myocardial contraction strength.4.Dobutamine is used to test myocardium viability and clinical treatment, traditional low dose(2-10μg/kg min)could hardly improve cardiac function.