| Objective: To assess the feasibility of evaluating left atrium (LA) function by strain rate imaging (SRI) and to detect the relation between left ventricular (LV) geometry and LA SR parameters in patients with primary hypertension. To explore a new quantitative method of evaluating LA function more straightly and sensitively.Methods1 The study included 30 healthy participants as the control group and 69 patients with primary hypertension. The patients were divided into groups of normal geometric LV (LN, n=28, mean age 51.81±9.74 years), concentric remodeling (CR, n=20, mean age 57.00±9.39 years),concentric hypertrophy (CH, n=10, mean age 54.30±17.68 years) and eccentric hypertrophy (EH, n=9, mean age 49.95±8.89 years).2 A color Doppler ultrasonic system (GE Vivid 7) with 1.5~4.0MHz transducer was used, and an Echopac 6.2 workstation was available for TVI and SRI quantitative analysis.3 All echocardiography studies were performed with the subjects lying in the left lateral decubitus position connected with electrocardiogram (ECG). Firstly, the standard LV wall motion curve and aorta-LA motion curve were acquired in M mode. Real-time 2D images in standard apical 4-chamber view were obtained. Secondly, mitral valve inflow and right superior pulmonary vein outflow Doppler velocity profiles were recorded using pulsed wave (PW) Doppler at a scan speed of 100mm/s. Finally, in TVI mode, unstandard apical 3-chamber view and 2-chamber view were recorded at a high frame rate of 160-200 frames/s. All the data mentioned above were recorded in 3 continuous cardiac cycle and were stored in hardware for off-line analysis in Echo Pac.4 Image analysis and parameter measurement4.1 According to the recommendation of ASE, LA dimension (LAD), interventricular septal thickness (IVST), LV posterior wall thickness (LVPWT), and end-diastolic dimension (Dd) were measured. LV mass (LVM), LV mass index (LVMI) and relative wall thickness (RWT) were calculated. LVM=0.8×1.04[(LVD+IVST+LVPWT)~3-LVD~3]+0.6,LVMI=LVM/BSA,RWT=(IVST+LVPWT)/Dd.4.2 Using Simpson's method, LV end-diastole volume (EDV), end-systole volume (ESV), minimum LA volume (Vmin) and maximum LA volume were measured. Pre-atrial contraction left atrial volume (Vprea) was measured at the onset of P wave. Then, LV ejection fraction (LVEF), active emptying fraction (AEF), expansion index (EI), passive emptying fraction (PEF) and ratio of PEF and AEF were calculated.4.3 Early-diastole peak velocity (VE), late-diastole peak velocity (VA) and their ratio (E/A) of mitral valve flow Doppler were measured.4.4 SR curves were assessed (sample volume 2mm×6mm, strain length 6mm) in the middle of the anterior, posterior and inferior LA walls in apical 2-chamber and 3-chamber views and the region of interest was manually tracked. Peak systolic SR (SRs), early diastolic SR (SRe), and late diastolic SR (SRa) were measured and the left atrium total SR was calculated by averaging the results for each segments.Results1 Comparison of traditional parametersThere were differences of LADI, E/A and S/D between hypertensive group and control group. Though the three parameters reflected the state of LVH from different parts, there were some differences. So, these three parameters could not reflect LA function comprehensively.2 Comparison of volume parametersVprea, Vmin and Vmax in hypertensive groups were significantly higher than control group (P<0.05), but the results among different hypertensive groups had no statistical significance.AEF in CH group was the highest (P <0.05); PEF in each hypertensive group was significant lower than control group (P<0.05), CH group had the lowest level in hypertensive groups, CH group < CR group < LN group < EH group. There were significant differences of P/A in all the groups and CH group CH group >CR group > LN group. Except the difference between LN group and EH group, the difference between any other two groups were insignificant.e/a in hypertensive groups were all smaller than one, and CH group |
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