Cardiac Rhythm Management Laboratory, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, AL.
J Am Heart Assoc. 2014 Feb 28;3(1):e000495. doi: 10.1161/JAHA.113.000495.
The mechanisms that maintain long duration ventricular fibrillation (LDVF) are unclear. The difference in distribution of the Purkinje system in dogs and pigs was explored to determine if Purkinje activation propagates to stimulate working myocardium (WM) during LDVF and WM pacing.
In-vivo extracellular recordings were made from 1044 intramural plunge and epicardial plaque electrodes in 6 pig and 6 dog hearts. Sinus activation propagated sequentially from the endocardium to the epicardium in dogs but not pigs. During epicardial pacing, activation propagated along the endocardium and traversed the LV wall almost parallel to the epicardium in dogs, but in pigs propagated away from the pacing site approximately perpendicular to the epicardium. After 1 minute of VF, activation rate near the endocardium was significantly faster than near the epicardium in dogs (P<0.01) but not pigs (P>0.05). From 2 to 10 minutes of LDVF, recordings exhibiting Purkinje activations were near the endocardium in dogs (P<0.01) but were scattered transmurally in pigs, and the WM activation rate in recordings in which Purkinje activations were present was significantly faster than the WM activation rate in recordings in which Purkinje activations were absent (P<0.01). In 10 isolated perfused dog hearts, the LV endocardium was exposed and 2 microelectrodes were inserted into Purkinje and adjacent myocardial cells. After 5 minutes of LDVF, mean Purkinje activation rate was significantly faster than mean WM activation rate (P<0.01).
These extracellular and intracellular findings about activation support the hypothesis that Purkinje activation propagates to stimulate WM during sinus rhythm, pacing, and LDVF.
维持长时间心室颤动（LDVF）的机制尚不清楚。本研究旨在探讨犬和猪浦肯野系统分布的差异，以确定在 LDVF 和 WM 起搏期间浦肯野激活是否传播以刺激工作心肌（WM）。
在 6 只犬和 6 只猪的 1044 个心内膜 plunge 和心外膜斑块电极中进行了体内细胞外记录。在犬中，窦性激活从心内膜向心外膜顺序传播，但在猪中则没有。在心外膜起搏期间，激活在犬中沿着心内膜传播并几乎平行于心外膜穿过 LV 壁，但在猪中则从起搏部位传播，大约垂直于心外膜。在 VF 持续 1 分钟后，心内膜附近的激活率明显快于犬（P<0.01）但不是猪（P>0.05）心外膜附近。在 LDVF 的 2 到 10 分钟期间，在犬中靠近心内膜的记录中出现了浦肯野激活（P<0.01），但在猪中则是散在的跨壁分布，并且在存在浦肯野激活的记录中，WM 的激活率明显快于不存在浦肯野激活的记录（P<0.01）。在 10 只分离的灌注犬心脏中，暴露 LV 心内膜并插入 2 个微电极到浦肯野和相邻的心肌细胞中。在 LDVF 持续 5 分钟后，浦肯野激活的平均速率明显快于 WM 激活的平均速率（P<0.01）。
这些关于激活的细胞外和细胞内发现支持浦肯野激活在窦性节律、起搏和 LDVF 期间传播以刺激 WM 的假说。
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