Saiz J, Ferrero J M, Monserrat M, Ferrero J M, Thakor N V
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.
IEEE Trans Biomed Eng. 1999 Feb;46(2):138-47. doi: 10.1109/10.740876.
Computer modeling is used to study the effect of electrical coupling between a myocardial zone where early afterdepolarizations (EAD's) can develop and the normal neighboring tissue. The effects of such coupling on EAD development and on the likelihood of EAD propagation as an ectopic beat are studied. The influence on EAD formation is investigated by approximating two partially coupled myocardial zones modeled as two active elements coupled by a junctional resistance R. For R values lower than 800 omega cm2, the action potentials are transmitted to the coupled element, and for R values higher than 850 omega cm2 they are blocked. In both ranges of R, when the electrical coupling increases, the EAD's appear at more negative takeoff potentials with higher amplitudes and upstrokes. The EAD's are not elicited if the electrical coupling is too high. In a separate model of two one-dimensional cardiac fiber segments partially coupled by a resistance R, critical R values exist, between 42 and 54 omega cm2, that facilitate EAD propagation. These results demonstrate that in myocardial zones favorable to the formation of EAD, the electrical coupling dramatically affects initiation of EAD and its spread to the neighboring tissue.
计算机建模用于研究可发生早期后除极（EAD）的心肌区域与相邻正常组织之间电耦合的影响。研究了这种耦合对EAD发生以及EAD作为异位搏动传播可能性的影响。通过将两个部分耦合的心肌区域近似为通过结电阻R耦合的两个活性元件，研究了对EAD形成的影响。当R值低于800Ω·cm²时，动作电位可传导至耦合元件；当R值高于850Ω·cm²时，动作电位则被阻断。在这两个R值范围内，当电耦合增加时，EAD会在更负的起始电位出现，且幅度和上升速度更高。如果电耦合过高，则不会引发EAD。在一个由电阻R部分耦合的两个一维心脏纤维段的单独模型中，存在促进EAD传播的临界R值，介于42至54Ω·cm²之间。这些结果表明，在有利于EAD形成的心肌区域中，电耦合会显著影响EAD的起始及其向相邻组织的传播。
