Gokhale Tanmay A, Medvescek Eli, Henriquez Craig S
Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708-0281, USA.
Chaos. 2017 Sep;27(9):093909. doi: 10.1063/1.4999605.
Cardiac arrhythmias have been traditionally simulated using continuous models that assume tissue homogeneity and use a relatively large spatial discretization. However, it is believed that the tissue fibrosis and collagen deposition, which occur on a micron-level, are critical factors in arrhythmogenesis in diseased tissues. Consequently, it remains unclear how well continuous models, which use averaged electrical properties, are able to accurately capture complex conduction behaviors such as re-entry in fibrotic tissues. The objective of this study was to compare re-entrant behavior in discrete microstructural models of fibrosis and in two types of equivalent continuous models, a homogenous continuous model and a hybrid continuous model with distinct heterogeneities. In the discrete model, increasing levels of tissue fibrosis lead to a substantial increase in the re-entrant cycle length which is inadequately reflected in the homogenous continuous models. These cycle length increases appear to be primarily due to increases in the tip path length and to altered restitution behavior, and suggest that it is critical to consider the discrete effects of fibrosis on conduction when studying arrhythmogenesis in fibrotic myocardium. Hybrid models are able to accurately capture some aspects of re-entry and, if carefully tuned, may provide a framework for simulating conduction in diseased tissues with both accuracy and efficiency.
传统上，心律失常是使用连续模型来模拟的，这些模型假定组织具有同质性，并采用相对较大的空间离散化。然而，据信在微米水平上发生的组织纤维化和胶原沉积是患病组织中心律失常发生的关键因素。因此，使用平均电学特性的连续模型能够多准确地捕捉诸如纤维化组织中的折返等复杂传导行为，仍不明确。本研究的目的是比较纤维化离散微观结构模型以及两种等效连续模型（均匀连续模型和具有明显异质性的混合连续模型）中的折返行为。在离散模型中，组织纤维化程度的增加会导致折返周期长度大幅增加，而这在均匀连续模型中未得到充分体现。这些周期长度的增加似乎主要是由于尖端路径长度的增加和恢复行为的改变，这表明在研究纤维化心肌中的心律失常发生时，考虑纤维化对传导的离散效应至关重要。混合模型能够准确捕捉折返的某些方面，并且如果仔细调整，可能会提供一个既能准确又能高效模拟患病组织中传导的框架。
