Traditional and Color M-Mode Parameters of Left Ventricular Diastolic Function During Low-Dose Dobutamine Stress Echocardiography: Relations to Contractility Reserve

Abstract

The study is aiming at assessing the role of traditional and color m-mode Doppler in evaluating the myocardial response to lusitropic effect of LDD in patients with previous myocardial infarction in addition to the traditional assessment of LV chamber contractility reserve by WMSI and EF. The study was conducted on Fifty patients referred to the cardiology department echocardiography lab Ain Shams University Hospital (Cairo, Egypt), for functional assessment of contractile reserve post myocardial infarction by low dose Dobutamine stress echocardiography. Inclusion criteria were previous myocardial infarction with impaired systolic function <45%. Atrial fibrillation, unstable angina, pacemaker cardiac rhythm, poor echocardiographic window as well as any contraindication to Dobutamine infusion were pretest exclusion criteria. Glo l systoli fun tion w s ss ss d using th Modifi d Simpson‘s rul LV volumes were traced at both end-diastole EDV and end-systole ESV from the apical four chamber view. LV contractility reserve was assessed by comparing resting and peak stress LV ejection fr tion with ΔEF>5% Regional wall motion was assessed according to the standard 16-segment model recommended by the American Society of Echocardiography. Individual segments were then sub-grouped based on the known vascular distribution. Regional wall motion was visually assessed for each segment individually – considering both endocardial excursion and systolic thickening – and each segment was assigned a score according to the semiquantitative scoring system described by Knudsen et al. Summery and Conclusion 111 During the standard protocol we assessed the following diastolic parameters both at rest and at LDD. Mitral inflow velocity and intervals (E, A, E/A, DT), isovolumic relaxation time IVRT, myocardial performance index (MPI), color Doppler M-mode flow propagation velocity (FPV, E/FPV) and tissue Doppler imaging of lateral mitral annulus ( é, á, E/ é). Our study showed that low dose Dobutamine improves systolic function in patients post myocardial infarction with impaired systolic function even at a dosage in which heart rate usually does not increase. Low dose Dobutamine induced significant changes in certain parameters of diastolic function (A, E/A, FPV and E/FPV). Although, there were significant correlations between certain parameters of diastolic function (E, DT, IVRT and E/é) with WMSI and EF as indicators of systolic function, only E wave velocity and E/é ratio were significantly different in the group of patients with viable myocardium from the group of patients without viable myocardium. Also there were lack of significant correlation between delta percent change of all diastolic parameters and viabili