Factors determining the magnitude of the pre-ejection leftward septal motion in left bundle branch block.
Factors determining the magnitude of the pre-ejection leftward septal motion in left bundle branch block.
复制标题
DOI：
10.1093/europace/euv381
复制
发表时间：
2016-12
期刊：
影响因子：
--
通讯作者：
Smiseth OA
中科院分区：
文献类型：
--
作者：
Remme EW;Niederer S;Gjesdal O;Russell K;Hyde ER;Smith N;Smiseth OA
在左束支阻滞（LBBB）患者中，经常观察到射血前室间隔异常大的向左运动。这种运动被认为是对心脏再同步化治疗（CRT）反应的预测因子。我们的目标是调查影响其大小的因素。测量了8只犬的左心室（LVP）和右心室（RVP）压力和左心室（LV）容积。LBBB、LVP诱导后，跨壁间隔压（PLV-RV = LVP - rvp）在中隔左移阶段升高较慢（P < 0.01）。双心室LBBB有限元模拟模型证实，室间隔左移的幅度取决于PLV-RV上升的减少。该模型显示，左室间隔运动减少，激活延迟缩短，整体或右心室收缩力降低，室间隔梗死，或当室间隔在舒张末期因右心室容量过载而已经移位到左室时。实验和模拟都表明，射血前室间隔过度收缩的发生，部分原因是由于正常的侧壁对这种推动作用的丧失，室间隔执行了更多的将血液推向二尖瓣小叶以关闭它们的工作。左束支阻滞降低射射前室间隔收缩的后负荷，表现为PLV-RV上升缓慢，这是左室间隔运动幅度的主要原因和决定因素。由于室间隔梗死、整体或右心室收缩力受损或右心室容量过载，运动可能很小或不存在，如果这种运动用于评价CRT反应，则应记住这一点。
An abnormal large leftward septal motion prior to ejection is frequently observed in left bundle branch block (LBBB) patients. This motion has been proposed as a predictor of response to cardiac resynchronization therapy (CRT). Our goal was to investigate factors that influence its magnitude. Left (LVP) and right ventricular (RVP) pressures and left ventricular (LV) volume were measured in eight canines. After induction of LBBB, LVP and, hence, the transmural septal pressure (PLV–RV = LVP–RVP) increased more slowly (P < 0.01) during the phase when septum moved leftwards. A biventricular finite-element LBBB simulation model confirmed that the magnitude of septal leftward motion depended on reduced rise of PLV–RV. The model showed that leftward septal motion was decreased with shorter activation delay, reduced global or right ventricular (RV) contractility, septal infarction, or when the septum was already displaced into the LV at end diastole by RV volume overload. Both experiments and simulations showed that pre-ejection septal hypercontraction occurs, in part, because the septum performs more of the work pushing blood towards the mitral valve leaflets to close them as the normal lateral wall contribution to this push is lost. Left bundle branch block lowers afterload against pre-ejection septal contraction, expressed as slowed rise of PLV–RV, which is a main cause and determinant of the magnitude of leftward septal motion. The motion may be small or absent due to septal infarct, impaired global or RV contractility or RV volume overload, which should be kept in mind if this motion is to be used in evaluation of CRT response.