SPREAD OF EXCITATION IN A MYOCARDIAL VOLUME - SIMULATION STUDIES IN A MODEL OF ANISOTROPIC VENTRICULAR MUSCLE ACTIVATED BY POINT STIMULATION
SPREAD OF EXCITATION IN A MYOCARDIAL VOLUME - SIMULATION STUDIES IN A MODEL OF ANISOTROPIC VENTRICULAR MUSCLE ACTIVATED BY POINT STIMULATION
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DOI：
10.1111/j.1540-8167.1993.tb01219.x
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发表时间：
1993-04-01
影响因子：
2.7
通讯作者：
TACCARDI, B
中科院分区：
文献类型：
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作者：
COLLI-FRANZONE, P;GUERRI, L;TACCARDI, B
简介：本研究的目的是模拟激发波前通过尺寸为 6.5 X 6.5 X 1.0 cm 的平行六面体心室组织板传播。方法和结果：该板结合了心肌的各向异性特性，包括从心外膜到心内膜的透壁逆时针纤维旋转。模拟基于确定整个心室壁激发时间的eikonal 模型，该模型表示为各向异性双域。通过在不同的壁内深度提供异位刺激来启动兴奋。我们还研究了简化的浦肯野网络对激励模式的影响。起搏平面中的激励波前与心外膜-心内膜表面平行，呈椭圆形，其主轴大致沿局部纤维方向取向，由于相邻平面中旋转纤维的吸引力而具有凸起和变形。波前与距起搏平面距离不断增加的平面的椭圆形交叉点顺时针或逆时针旋转，具体取决于起搏深度，但波前旋转始终小于同一平面中的纤维旋转。对于所有起搏深度，兴奋返回到起搏平面。根据起搏深度，在板层的多个不同扇区中发生返回，并且在距起搏位置 6 毫米处观察到返回。结论：波前曲率和与板层边界的碰撞显着影响局部速度。心外膜等时线的形状和间隔以及心外膜速度的空间分布随着起搏部位和深度的变化而变化。当浦肯野网络添加到模型中时，心外膜速度揭示了浦肯野心肌连接处的心内膜下位置。从心外膜等时线中可以获得对壁内事件的大量了解。如果经过实验验证，结果可能适用于手术时记录的心外膜等时线。
Introduction: The purpose of this study was to present simulations of excitation wavefronts spreading through a parallelepipedal slab of ventricular tissue measuring 6.5 X 6.5 X 1.0 cm.Methods and Results: The slab incorporates the anisotropic properties of the myocardium including the transmural counterclockwise fiber rotation from epicardium to endocardium. Simulations were based on an eikonal model that determines excitation times throughout the ventricular wall, which is represented as an anisotropic bidomain. Excitation was initiated by delivering ectopic stimuli at various intramural depths. We also investigated the effect of a simplified Purkinje network on excitation patterns. Excitation wavefronts in the plane of pacing, parallel to epicardial-endocardial surfaces, were oblong with the major axis approximately oriented along the local fiber direction, with bulges and deformations due to attraction from rotating fibers in adjacent planes. The oblong intersections of the wavefront with planes at increasing distance from pacing plane rotated clockwise or counterclockwise, depending on pacing depth, but wavefront rotation was always less than fiber rotation in the same plane. For all pacing depths, excitation returned toward the plane of pacing. Return occurred in multiple, varying sectors of the slab depending on pacing depth, and was observed as close as 6 mm to the pacing site.Conclusion: Curvature of wavefronts and collision with boundaries of slab markedly affected local velocities. Shape and separation of epicardial isochrones and spatial distribution of epicardial velocities varied as a function of site and depth of pacing. When the Purkinje network was added to the model, epicardial velocities revealed the subendocardial location of the Purkinje-myocardial junctions. Considerable insight into intramural events could be obtained from epicardial isochrones. If validated experimentally, results may be applicable to epicardial isochrones recorded at surgery.