Hillebrenner Matthew G, Eason James C, Campbell Craig A, Trayanova Natalia A
Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA.
J Cardiovasc Electrophysiol. 2003 Oct;14(10 Suppl):S249-56. doi: 10.1046/j.1540.8167.90317.x.
Recent evidence has demonstrated that defibrillation shocks terminate or reset reentrant activity in the myocardium through the generation of virtual electrode polarization (VEP). Previous research has revealed that the shock establishes phase singularities (PSs) in the tissue via the VEP mechanism. The aim of this study was to examine, as a function of shock strength and electrode configuration, the relationship between end-shock PSs and the reentrant circuits established after failed defibrillation attempts.
The study uses a complex three-dimensional finite-element bidomain model of a slice of the canine heart characterized by realistic geometry and fiber architecture and undergoing a single scroll wave. Defibrillation shocks of increasing strength are delivered through three different electrode configurations. The results demonstrated that >98% of all PSs have a lifetime of half a reentrant cycle or less. Stronger shocks result in a faster rate of annihilation of postshock PSs. For failed shocks, the surviving PSs underlie the activity of one or more scroll waves, which remain stationary in the slice. For all electrode configurations tested, the increase in shock strength leads to a rapid initial increase in the number of postshock reentries followed by a slower decrease; similar behavior is observed with regard to end-shock PSs.
These results present new evidence regarding the mechanisms underlying failure of defibrillation shocks.
最近的证据表明，除颤电击通过产生虚拟电极极化（VEP）来终止或重置心肌中的折返活动。先前的研究表明，电击通过VEP机制在组织中建立相奇点（PSs）。本研究的目的是作为电击强度和电极配置的函数，研究电击结束时的PSs与除颤尝试失败后建立的折返电路之间的关系。
该研究使用了一个复杂的三维有限元双域模型，该模型模拟犬心切片，具有逼真的几何形状和纤维结构，并存在单个螺旋波。通过三种不同的电极配置施加强度不断增加的除颤电击。结果表明，所有PSs中>98%的寿命为半个折返周期或更短。更强的电击会导致电击后PSs的湮灭速度更快。对于失败的电击，存活的PSs是一个或多个螺旋波活动的基础，这些螺旋波在切片中保持静止。对于所有测试的电极配置，电击强度的增加会导致电击后折返次数迅速初始增加，随后缓慢减少；在电击结束时的PSs方面也观察到类似的行为。
这些结果为除颤电击失败的潜在机制提供了新的证据。
