右心室心尖不同部位起搏时左心室收缩时序的超声研究

目的探讨右心室心尖不同部位起搏时左心节段性室壁的收缩特征及时序。方法利用实时三维超声心动图技术确定右心室心尖起搏电极顶端在右心室心尖部的准确空间附着位点。运用应变显像技术，测定左心室壁各节段收缩期应力的达峰时间，即自心电图Q波起点至收缩期峰值应变时限（interval between Q wave of surface ECG and peak strain，QPSI），反映左心室各室壁的收缩时序；并计算QPSI的离散度，即最大QPSI减去最小QPSI的时限差，代表左心室内收缩延迟时间。观察正常对照组、右心室心尖不同部位起搏组左心室壁的节段性运动，评价各组左心室壁的收缩（或应变）时序及收缩协调性。结果右心室心尖起搏组的左心室壁收缩时序较正常对照组发生改变。右心室心尖侧壁起搏与右心室心尖间隔起搏组的左心室壁收缩时序不同，左室间隔心尖段、后壁基底段差异存在统计学意义（P〈0．05）。右心室心尖起搏时左室壁整体的收缩发生延迟，并且右心室心尖侧壁起搏组左室壁的收缩延迟时间明显大于右心室心尖间隔起搏组（P〈0．05）。结论右心室心尖不同部位起搏可以导致左心室不同的收缩模式改变，提示右心室心尖不同部位起搏所引起的电激动顺序及对心脏血流动力学的影响也存在差异。

Sequence assessement of the myocardial contraction within regional left ventricular wall during pacing at variant right ventricular apical sites

Objective To assess the left ventricular contraction characteristics and sequence during pacing at variant right ventricular apical sites.Methods With the real-time three-dimensional echocardiography, the exact spatial sites of the pacemaker leads at right ventricular apex were located.Left ventricular wall motion was assessed by strain Doppler imaging,and the internal between the Q wave of the surface ECG and the peak strain(QPSI) was measured in three segments of the septal,lateral,inferior,anterior,and posterior wall respectively to represent the contraction sequence of the left ventricular wall.Intraventricular contraction delay was determined as the time difference between minimum and maximum QPSI(QPSI-d).Results During right ventricular apical pacing,the contraction sequence of the left ventricular wall changed and there was a big difference in the left ventricular wall contraction sequence between the groups of the right ventricular lateral apical pacing and septal apical pacing.During right ventricular apical pacing,the contraction of the whole left ventricular delayed,and the intraventricular contraction delay during right ventricular lateral apical pacing was greater than that during septal apical pacing(P<(0.05)).Conclusions The temporal sequence difference of the left ventricular contraction during pacing at variant right ventricular apical sites has been demonstrated,which indicated that right ventricular apical pacing at variant sites could induce different electrical activation sequence and homodynamic status subsequently.