Clinical Studies Of Left Ventricular Systolic Function Of Essential Hypertensive Patient By Two-dimensional Speckle Tracking Imaging

Objective: Essential hypertension(EH) is a common clinical cardiovascular disease, which can do damage to heart, brain, kidney and other target organs of human body. The main symptoms of heart damage are left ventricular hypertrophy and left cardiac insufficiency, which displays as left ventricular diastolic dysfunction at its early stage. The diastolic dysfunction would turn into left ventricular systolic dysfunction if the patients were not treated punctually and effectively. Once the left cardiac insufficiency occurs, the illness often deteriorates rapidly. Therefore, timely and effective evaluation of cardiac function in patients with EH is of great significance to the prevention of other complications induced by hypertension. Ultrasound speckle tracking imaging(STI) is a new developed noninvasive method for assessment of myocardial function by measuring myocardial velocity,strain and strain rate. It analyzes motion by tracking speckles in the 2D ultrasonic image[1]. This study was conducted to evaluate ultrasonic two-dimensional speckle tracking imaging(STI) in assessment of left ventricular systolic function, so as to provide evidence for clinical evaluation of the cardiac function in hypertensive patients.Methods: 56 patients(either as outpatient or hospitalized patients) with essential hypertension in the department of cardiovascular medicine of Nanyang NO.2 people’s hospital from November 2013 to August 2014 were selected as the study objects. All patients were divided into two groups according to left ventricular mass index(LVMI). Male with LVMI > 134 g/m2 and female with LVMI > 110 g/m2 are defined as left ventricular hypertrophy(LVH) patients. Group A contains 36 patients with no left ventricular hypertrophy(referred as NLVH group). Group B contains 20 patients with left ventricular hypertrophy(referred as LVH group). 54 healthy volunteers with matched ages and genders(with the hypertensive patients) were chosen as the control group. Volunteers with the following illness were excluded: liver, kidney dysfunction; abnormal blood calcium and glucose metabolism; secondary hypertension; Coronary heart disease; cardiac disease; valvular heart disease; acute myocarditis; hypertrophic cardiomyopathy; Pulmonary arterial hypertension, pulmonary heart disease; endocrine system diseases such as hyperthyroidism, hypothyroidism and Cushing’s syndrome, etc. Echocardiographic examination were performed and some parameters were acquired, including left atrium diameter(LAD), left ventricular end-diastolic diameter(LVEDd), left ventricular end-systolic diameter(LVEDs), diastolic interventricular septal thickness(IVSTd), diastolic posterior wall thickness(LVPWTd), peak early inflow velocity of mitral valve(E) and peak atrial contraction velocity(A). Using twodimensional speckle tracking imaging technology to evaluate the local/global myocardial systolic and diastolic function by quantitatively determining the myocardial strain via ultrasonic two-dimensional gray-scale image. High frame rate two-dimensional(2D) images of three consecutive cardiac cycles were recorded from the left ventricular(LV) apical four-chamber view, two-chamber view, long-axis view and the short-axis views at the levels of mitral annulus, papillary muscle and apex of the LV, respectively. 2D images were transferred to Qlab6.0 work station for offline strain analysis. The longitudinal strain(LS) values in the inner and outer layers of myocardium were measured in the left ventricular apical views. Radial strain(RS) and circumferential strain(CS) values in the inner and outer layers of myocardium were measured in the left ventricular short-axis views using two-dimensional strain software. Acquired the peak systolic strain of each segment, calculated the average strain value of three consecutive cardiac cycles as the peak systolic strain. The average strain values of the basal segment, the middle segment, the apical segment of the LV long axis and mitral annulus, papillary muscle and apex of the LV short axis in the inner and outer layers were calculated as the LV global LS, RS and CS of each level.Results: The LAD, peak E, peak A and E/A value in Group A and Group B were both higher than those in the control group. Besides, the IVST, LVPWT, LVMI in Group B were significantly higher than those in Group A and in the control group. In the inner layers of myocardium, the peak systolic LS, RS and CS values of different segments showed higher than those of the outer layers in all the groups. The average LS and the LV global LS in Group B were significantly lower than those in the control group. However, the RS and CS values at each level showed no significant difference with the control group. The average and the LV global LS, RS and CS values in group B were significantly lower than those in Group A and the control group.Conclusion: The LVEF value that measured by conventional echocardiography is normal in patients with essential hypertension. However, the left ventricular diastolic function of the patients with essential hypertension has already begun to decline. Twodimensional speckle tracking imaging(STI) has the potentiality to be used clinically to evaluate the left ventricular systolic function in hypertension patients.