Department of Electrical and Computer Engineering, University of Calgary, Calgary, Canada.
Heart Rhythm. 2009 Dec;6(12):1782-9. doi: 10.1016/j.hrthm.2009.08.023. Epub 2009 Aug 22.
The function of the Purkinje system (PS) is to ensure fast and uniform activation of the heart. Although this vital role during sinus rhythm is well understood, this is not the case when shocks are applied to the heart, especially in the case of failed defibrillation. The PS activates differently from the myocardium, has different electrophysiological properties, and provides alternate propagation pathways; thus, there are many ways in which it can contribute to postshock behavior.
The purpose of this study was to elucidate the role of the PS in the initiation and maintenance of postshock arrhythmias.
A computer model of the ventricles including the PS was subjected to different reentry induction protocols.
The PS facilitated reentry induction at relatively weaker shocks. Disconnecting the PS from the ventricles during the postshock interval revealed that the PS helps stabilize early-stage reentry by providing focal breakthroughs. During later stages, the PS contributed to reentry by leading to higher frequency rotors. The PS also promoted wave front splitting during reentry due to electrotonic coupling, which prolongs action potential durations at PS-myocyte junctions. The presence of a PS results in the anchoring of reentrant activations that propagate through the pathways provided by the PS.
The PS is proarrhythmic in that it provides pathways that prolong activity, and it plays a supplementary role in maintaining the later stages of reentry (>800 ms).
浦肯野系统（PS）的功能是确保心脏快速、均匀地激活。尽管在窦性节律期间其这一重要作用已被充分理解，但在对心脏施加电击时情况并非如此，尤其是在除颤失败的情况下。PS 的激活方式不同于心肌，具有不同的电生理特性，并提供替代的传播途径；因此，它可以通过多种方式对电击后行为产生影响。
本研究旨在阐明 PS 在电击后心律失常的发生和维持中的作用。
一个包含 PS 的心室计算机模型被应用于不同的折返诱导方案。
PS 有助于在相对较弱的电击下诱导折返。在电击后间期将 PS 与心室分离后发现，PS 通过提供局灶性突破来帮助稳定早期折返。在后期，PS 通过导致更高频率的转子来促进折返。PS 还通过电紧张耦合在折返过程中促进波前分裂，从而延长 PS-心肌细胞连接处的动作电位持续时间。PS 的存在导致通过 PS 提供的途径传播的折返激活的锚定。
PS 具有致心律失常作用，因为它提供了延长活动的途径，并且在维持折返的后期阶段（>800ms）发挥补充作用。
