Pluijmert Marieke, Bovendeerd Peter H M, Lumens Joost, Vernooy Kevin, Prinzen Frits W, Delhaas T
Maastricht University, Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands.
Eindhoven University of Technology, Eindhoven, The Netherlands.
Europace. 2016 Dec;18(suppl 4):iv94-iv103. doi: 10.1093/europace/euw355.
Cardiac resynchronization therapy (CRT) produces clinical benefits in chronic heart failure patients with left bundle-branch block (LBBB). The position of the pacing site on the left ventricle (LV) is considered an important determinant of CRT response, but the mechanism how the LV pacing site determines CRT response is not completely understood. The objective of this study is to investigate the relation between LV pacing site during biventricular (BiV) pacing and cardiac function.
We used a finite element model of BiV electromechanics. Cardiac function, assessed as LV dp/dt and stroke work, was evaluated during normal electrical activation, typical LBBB, fascicular blocks and BiV pacing with different LV pacing sites. The model replicated clinical observations such as increase of LV dp/dt and stroke work, and the disappearance of a septal flash during BiV pacing. The largest hemodynamic response was achieved when BiV pacing led to best resynchronization of LV electrical activation but this did not coincide with reduction in total BiV activation time (∼ QRS duration). Maximum response was achieved when pacing the mid-basal lateral wall and this was close to the latest activated region during intrinsic activation in the typical LBBB, but not in the fascicular block simulations.
In these model simulations, the best cardiac function was obtained when pacing the mid-basal LV lateral wall, because of fastest recruitment of LV activation. This study illustrates how computer modeling can shed new light on optimizing pacing therapies for CRT. The results from this study may help to design new clinical studies to further investigate the importance of the pacing site for CRT response.
心脏再同步治疗（CRT）对慢性心力衰竭合并左束支传导阻滞（LBBB）患者具有临床益处。左心室（LV）起搏部位被认为是CRT反应的重要决定因素，但LV起搏部位如何决定CRT反应的机制尚未完全明确。本研究的目的是探讨双心室（BiV）起搏时LV起搏部位与心功能之间的关系。
我们使用了一个BiV机电有限元模型。在正常电激活、典型LBBB、分支阻滞以及不同LV起搏部位的BiV起搏过程中，以LV dp/dt和每搏功评估心功能。该模型复制了临床观察结果，如BiV起搏时LV dp/dt和每搏功增加以及室间隔闪烁消失。当BiV起搏导致LV电激活最佳再同步时，可实现最大的血流动力学反应，但这与总BiV激活时间（~QRS波时限）的缩短并不一致。起搏基底外侧壁中部时可实现最大反应，这与典型LBBB固有激活过程中最晚激活区域接近，但在分支阻滞模拟中并非如此。
在这些模型模拟中，起搏LV基底外侧壁中部时可获得最佳心功能，因为LV激活的募集最快。本研究说明了计算机建模如何为优化CRT起搏治疗提供新的思路。本研究结果可能有助于设计新的临床研究，以进一步探讨起搏部位对CRT反应的重要性。
