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目的探索利用超声心动图二维斑点追踪(2DSTE)应变成像技术无创性间接标测左心室(LV)电激动顺序的方法。方法选择健康成人12例(N组)、QRS波正常但ST-T异常者18例(R组)及左束支传导阻滞者26例(D组)。使用2DSTE分析LV3个标准心尖切面长轴应变,对于存在收缩早期正向应变的节段以心电信号R波峰为起点测量正向应变达峰时间为收缩起始时间(OTS),对于收缩早期为负向应变的所有节段测量第二帧时的应变值(S_n),以S_n的最大绝对值(S)计算2帧间(时间为T)的应变速率(-S/T),通过公式OTS_n=T-S_n/(-S/T)计算OTS。使用17节段模型的OTS表示LV机械激动顺序(MAS),并以17节段OTS的平均值和标准差表示LV全局收缩起始时间(OTSG)和离散度(OTSSD)。比较MAS与公认的心内膜面电激动顺序(EAS)的一致性,并比较3组间OTSG、OTSSD及相应节段OTS的差异性。结果 N组LV中段较早收缩,其中下壁、侧壁和前壁中段最早,心尖段略迟,基底段更迟,尤以后壁基底段最迟。R组与N组接近。D组以前间隔中段最早,冲动沿室壁圆周方向或心尖方向朝LV游离壁扩布,侧壁及后壁中间段和基底段均较迟激动。3组MAS均与EAS大体一致。N组与R组OTS_G、OTS_(SD)及相应节段OTS均无统计学差异(P均>0.05),D组OTS_G和OTS_(SD)均大于N组与R组,差异有统计学意义(P均<0.05),下壁中段OTS较N组显著延迟(P<0.05)。结论确切测算节段心肌收缩起始时间可间接地无创性地标测LV电激动顺序。
Objective To explore a noninvasive and indirect method of determining the order of left ventricular (LV) electrical activation using 2DSTE 2D-EUS. Methods Twelve patients (group N) with normal QRS wave, 18 patients with abnormal ST-T (group R) and 26 patients with left bundle branch block (group D) were selected. The long axis strain of LV3 standard apical section was analyzed by 2DSTE. The peak of forward strain was measured as the onset time of contraction (OTS) for the segment with early positive strain of contraction as the starting point of R wave of contraction of ECG. The strain values (S_n) at the second frame are measured for all segments of the negative strain and the strain rate (-S / T) between 2 frames (time T) is calculated with the maximum absolute value of S_n (S) = T-S_n / (- S / T). OTS using a 17-segment model represents LV mechanical activation sequence (MAS) and LV global contraction onset time (OTSG) and dispersion (OTSSD) are expressed as mean and standard deviation of 17-segment OTS. The agreement between MAS and the accepted endocardial electro-active sequence (EAS) was compared, and the differences of OTSG, OTSSD and corresponding segment OTS among the three groups were compared. Results In the N group, the LV middle segment contracted earlier. The middle segment of the inferior wall, the lateral wall and the anterior wall were the earliest. The apical segment was slightly late, and the basal segment was later, especially the posterior wall basal segment. R group and N group close. In group D, the earliest middle part of the interval was the earliest. The impulse was spread toward the LV free wall along the circumferential direction of the ventricular wall or apical direction, and the middle and basal segments of the lateral and posterior wall were delayed. The three groups of MASs are generally consistent with EAS. The OTS_G, OTS_ (SD) and the corresponding segment OTS in group N and group R were not significantly different (all P> 0.05). The OTS_G and OTS_ (SD) in group D were significantly higher than those in group N and R P <0.05). OTS in the middle inferior wall was significantly delayed than that in the N group (P <0.05). Conclusion Accurately measure the onset of segmental myocardial contractility can be indirect noninvasive labeling of LV electrical activation sequence.