RESUMO
Objective To investigate the value of quantitative analysis of the left ventricular longitudinal strain in patients with hypertrophic cardiomyopathy (HCM) and with normal left ventricular ejection fraction (LVEF) by using two-dimensional speckle tracking imaging.Methods Twenty-eight HCM patients with normal LVEF (all of the cases were non obstructive HCM),who were diagnosed by clinical and ultrasound echocardiography between January 1,2015 and January 1,2016 in the First Affiliated Hospital of Dalian Medical University,served as the experimental group.And twenty healthy volunteers served as the healthy control group.The peak longitudinal strain (LPS) of the left ventricle and the systolic peak of the left ventricle were calculated by the STE technique.The indexes such as the transmural gradient (△ LS=LPSEndo-LPSEpi)and the transmural gradient percentage (△ LS％=△ LS/LPSEndo) were calculated.The Peak systolic longitudinal strain of endocardium (LPSEndo),the peak systolic longitudinal strain of mid-cardium (LPSMid),the peak systolic longitudinal strain of epicardium (LPSEpi),the peak systolic longitudinal strain of basal segment (LPSb),the peak systolic longitudinal strain of middle segment (LPSm),the peak systolic longitudinal strain of apical segment (LPSa),the global peak systolic longitudinal strain (GLPS) and other left ventricular myocardial strain,such as △ LS,△ LS％,in both the HCM group and the healthy control group,were analyzed by using independent samples t test comparison.For each layer of the left ventricle and the overall myocardial longitudinal strain,two independent sample t test was used for comparison between groups,and LSD-t test was used for intra-group comparison.Results (1) There was a gradient of LPS among the three layers and the three segments in both of the two groups:LPSEndo and LPSMid [(18.36±4.97)％ vs (13.80±4.23)％,(26.41±2.93)％ vs (22.19±2.49)％],the difference was statistically significant (t=5.550,8.529,P ＜ 0.05);LPSEndo and LPSEpi [(18.36±4.97) ％ vs (11.91 ±3.63)％,(26.41±2.93)％ vs (19.43±2.20)％],the difference was statistically significant (t=5.550,8.529,P ＜ 0.05);There was significant difference between LPSMid and LPSEpi in the healthy control group [(22.19 ± 2.49)％ vs (19.43 ± 2.20)％,t=3.709,P ＜ 0.05)],that was,LPSEndo ＞ LPSMid ＞ LPSEpi.LPSa and LPSm,the difference was statistically significant (t=4.029,6.839,P ＜ 0.05);LPSa and LPSb,the difference was statistically significant (t=5.304,9.887,P ＜ 0.05);There was significant difference between LPSm and LPSb in the healthy control group (t=4.170,P ＜ 0.05);that was,LPSa ＞ LPSm ＞ LPSb.In the HCM group,LPS in the 3 layers,3 segments,and the whole left ventricular wall were lower than that of the the healthy control group,the differences were statistically significant [GLPS:(14.63± 3.75)％ vs (22.68±2.51)％,t=-8.347;LPSEndo to LPSEpi:t=-6.477,-7.909,-8.242;LPSa to LPSb:t=-6.647,-8.790,-7.267;all P ＜ 0.05).(2) Compared with the healthy control group,both the segmental gradient and global transmural gradient in the HCM group were found reduced,but the difference had no statistical significance (all P ＞ 0.05).(3) The transmural gradient percentage both in the healthy control group and the HCM group were reduced from the apical segment to the basal segment,the difference were statistically significant (HCM group:t=9.985,5.969;healthy control group:t=17.513,7.043;all P ＜ 0.05).Compared with the healthy control group,the △ LS％a and the △ LS％m of HCM group were significantly higher [(58.86± 11.32)％ vs (43.70±4.73)％,(28.43± 11.48)％ vs (20.30± 3.66)％],and the difference was statistically significant (t=5.634,3.049,all P ＜ 0.05).Conclusions (1) Using 2D-STI could accurately determine the regional or the global left ventricular systolic function in patients with HCM.(2) The transmural gradient percentage can be more sensitive to reflect the change of the transmural gradient,and more research needed to explore its value for clinical application.