Clinical Study Of The Relationship Between Regional Left Ventricular Relaxation Asynchrony And Early Diastolic Flow Propagation Velocity In Hypertensive Patients

Objective To investigate regional left ventricular relaxation asynchrony and left ventricular early diastolic flow propagation velocity (Vp) in patients with essential hypertension by using color M-mode Doppler and tissue Doppler imaging;to elucidate the acute changes of regional left ventricular relaxation asynchrony and Vp after nifedipine was administered sublingually as well as the relationship between them. Methods In 23 patients with essential hypertension and 25 healthy volunteers.Blood measurement and echocardiography were finished respectively before and 1 hour after nifedipine was administered sublingually. The left ventricular internal dimension at end diastole (LVIDd), interventricular septal thickness at end diastole (IVSd) and left ventricular posterior wall thickness at end diastole (LVPWd) were measured in the parastemal long axis view by transthoracic two-dimensional echocardiography, and to calculate left ventricular ejection fraction (EF) with Teichholtz formula and left ventricular mass (LVM) with modified Devereux formula, left ventricular mass index (LVMI)=LVM/body surface area. From the apical four chamber and two chamber view, the basical segment and middle segment of interventricular septal, left ventricular lateral wall, anterior wall and inferior wall were obtained by tissue Doppler imaging, Regional left ventricular relaxation asynchrony index (AI) was calculated. From the apical four chamber view, left ventricular early diastolic flow propagation velocity (Vp) was measured by color M-mode echocardiography. Results There were no significant deferrence in gender, age, heart rate, LVIDd and EF between hypertensive group and control group(all P>0.05). Blood pressure, IVSd, LVPWd, LVMI and AI were larger (all P<0.01) in hypertensive group than in control group while Vp was lower (P<0.01) in hypertensive group. After administration of nifedipine heart rate increased (P<0.01) and blood pressure decreased (all P<0.05 or P<0.01) in control group, while heart rate and Vp increased (all P<0.01), blood pressure and AI decreased (all P<0.01) in hypertensive group, but other parameters have no significant change(all P>0.05) in two groups. Multiple stepwise regression analysis in hypertensive group before administration of nifedipine showed that AI and mean blood pressure were two independent determinants of V_P (P<0.001 or P<0.05), but other parameters have no correlation to Vp (all P>0.05). Linear correlation analysis after administration of nifedipine showed that the percent change in V_P correlated strongly with the percent change in AI (r=-0.74, P<0.01), but weakly with the percent change in mean blood pressure (r=-0.41, P<0.05) in hypertensive group, there were no correlation between the percent change in V_P and the percent change in mean blood pressure (r=-0.13, P>0.05) in control group, the percent change in V_P and the percent change in heart rate(respectively r=0.10, P>0.05;r=0.08, i>>0.05) in two groups. Conclusions AI increases and Vp decreases in patients with hypertension. Regional left ventricular asynchrony in relaxation and mean blood pressure are two dependent determinants of Vp in hypertensive patients. At the same time of decreasing blood pressure efficiently, reduced regional left ventricular asynchrony in relaxation after the administration of nifedipine contributes increased Vp in hypertensive patients.Vp has important clinical value in assessment of left ventricular diastolic function, treatment effectiveness evaluation and the appraisal of the prognosis in hypertension.