Department of Pharmacology and Physiology, Institute of Biomedical Engineering, Université de Montréal, Montréal, QC H3T 1J4, Canada.
Research Center, Hôpital du Sacré-Cœur de Montréal, 5400 boul. Gouin Ouest, Montréal, QC H4J 1C5, Canada.
Europace. 2021 Mar 4;23(23 Suppl 2):i169-i177. doi: 10.1093/europace/euab001.
The aim of this study is to design a computer model of the left atrium for investigating fibre-orientation-dependent microstructure such as stringy fibrosis.
We developed an approach for automatic construction of bilayer interconnected cable models from left atrial geometry and epi- and endocardial fibre orientation. The model consisted of two layers (epi- and endocardium) of longitudinal and transverse cables intertwined-like fabric threads, with a spatial discretization of 100 µm. Model validation was performed by comparison with cubic volumetric models in normal conditions. Then, diffuse (n = 2904), stringy (n = 3600), and mixed fibrosis patterns (n = 6840) were randomly generated by uncoupling longitudinal and transverse connections in the interconnected cable model. Fibrosis density was varied from 0% to 40% and mean stringy obstacle length from 0.1 to 2 mm. Total activation time, apparent anisotropy ratio, and local activation time jitter were computed during normal rhythm in each pattern. Non-linear regression formulas were identified for expressing measured propagation parameters as a function of fibrosis density and obstacle length (stringy and mixed patterns). Longer obstacles (even below tissue space constant) were independently associated with prolonged activation times, increased anisotropy, and local fluctuations in activation times. This effect was increased by endo-epicardial dissociation and mitigated when fibrosis was limited to the epicardium.
Interconnected cable models enable the study of microstructure in organ-size models despite limitations in the description of transmural structures.
本研究旨在设计左心房计算机模型，以研究纤维方向依赖性的微观结构，如线状纤维化。
我们开发了一种从左心房几何形状和心外膜和心内膜纤维方向自动构建双层互联电缆模型的方法。该模型由两层（心外膜和心内膜）的纵轴和横轴电缆交织而成，具有 100µm 的空间离散化。通过与正常条件下的立方体积模型进行比较来验证模型的准确性。然后，通过在互联电缆模型中解耦纵轴和横轴的连接，随机生成弥漫性（n=2904）、线状（n=3600）和混合纤维化模式（n=6840）。纤维化密度从 0%变化到 40%，线状障碍物的平均长度从 0.1 毫米变化到 2 毫米。在每种模式下的正常节律中计算总激活时间、表观各向异性比和局部激活时间抖动。确定了非线性回归公式，以表示测量的传播参数作为纤维化密度和障碍物长度（线状和混合模式）的函数。即使障碍物长度低于组织空间常数，较长的障碍物也与激活时间延长、各向异性增加以及激活时间局部波动有关。这种影响在心内膜-心外膜分离时增加，并在纤维化仅限于心外膜时减轻。
尽管在描述贯穿壁结构方面存在限制，但互联电缆模型能够在器官大小模型中研究微观结构。
