Mazeh Nachaat, Roth Bradley J
Department of Physics, Oakland University, Rochester, Michigan 48309, USA.
Heart Rhythm. 2009 Mar;6(3):361-7. doi: 10.1016/j.hrthm.2008.11.010. Epub 2008 Nov 17.
The strongest shock that induces reentry in the heart is the upper limit of vulnerability (ULV). In order to understand defibrillation, one must know what causes the ULV.
The goal of this study was to examine the mechanism of the upper limit of vulnerability.
Numerical simulations of cardiac tissue were performed using the bidomain model. An S2 shock was applied during the refractory period of the S1 action potential, and results using a smooth curving fiber geometry were compared with results using a smooth plus random fiber geometry.
When using a smooth fiber geometry only, no ULV was observed. However, when a random fiber geometry was included, the ULV was present. The difference arises from the fate of the shock-induced break wave front when it reaches the edge of the tissue hyperpolarized by the shock (the virtual anode).
Our numerical simulations suggest that local heterogeneities throughout the tissue may be crucial for determining the fate of the shock-induced wave front at the edge of the virtual anode, and therefore play an important role in the mechanism underlying the ULV.
诱发心脏折返的最强电击是易损上限（ULV）。为了理解除颤，必须了解导致易损上限的原因。
本研究的目的是探讨易损上限的机制。
使用双域模型对心脏组织进行数值模拟。在S1动作电位的不应期施加S2电击，并将使用平滑弯曲纤维几何结构的结果与使用平滑加随机纤维几何结构的结果进行比较。
仅使用平滑纤维几何结构时，未观察到易损上限。然而，当包含随机纤维几何结构时，易损上限出现。差异源于电击诱发的破碎波前到达被电击超极化的组织边缘（虚拟阳极）时的命运。
我们的数值模拟表明，整个组织中的局部异质性可能对于确定虚拟阳极边缘处电击诱发波前的命运至关重要，因此在易损上限的潜在机制中起重要作用。
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