Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah 84112-5000, USA.
Am J Physiol Heart Circ Physiol. 2010 Nov;299(5):H1405-18. doi: 10.1152/ajpheart.00419.2010. Epub 2010 Aug 27.
Long-duration ventricular fibrillation (LDVF) in the globally ischemic heart is a common setting of cardiac arrest. Electrical heterogeneities during LDVF may affect outcomes of defibrillation and resuscitation. Previous studies in large mammalian hearts have investigated the role of Purkinje fibers and electrophysiological gradients between the endocardium (Endo) and epicardium (Epi). Much less is known about gradients between the right ventricle (RV) and left ventricle (LV) and within each chamber during LDVF. We studied the transmural distribution of the VF activation rate (VFR) in the RV and LV and at the junction of RV, LV, and septum (Sep) during LDVF using plunge needle electrodes in opened-chest dogs. We also used optical mapping to analyze the Epi distribution of VFR, action potential duration (APD), and diastolic interval (DI) during LDVF in the RV and LV of isolated hearts. Transmural VFR gradients developed in both the RV and LV, with a faster VFR in Endo. Concurrently, large VFR gradients developed in Epi, with the fastest VFR in the RV-Sep junction, intermediate in the RV, and slowest in the LV. Optical mapping revealed a progressively increasing VFR dispersion within both the LV and RV, with a mosaic presence of fully inexcitable areas after 4-8 min of LDVF. The transmural, interchamber, and intrachamber VFR heterogeneities were of similar magnitude. In both chambers, the inverse of VFR was highly correlated with DI, but not APD, at all time points of LDVF. We conclude that the complex VFR gradients during LDVF in the canine heart cannot be explained solely by the distribution of Purkinje fibers and are related to regional differences in the electrical depression secondary to LDVF.
长时间室颤（LDVF）在全球缺血性心脏是心脏骤停的常见情况。在 LDVF 期间的电异质性可能会影响除颤和复苏的结果。以前在大型哺乳动物心脏中的研究已经研究了浦肯野纤维的作用以及心内膜（Endo）和心外膜（Epi）之间的电生理梯度。在 LDVF 期间，关于右心室（RV）和左心室（LV）之间以及每个心室内部的梯度的了解要少得多。我们使用 plunged 针电极在开胸犬中研究了 LDVF 期间 RV 和 LV 以及 RV、LV 和中隔（Sep）交界处的 VF 激活率（VFR）的跨壁分布。我们还使用光学映射来分析在 RV 和 LV 中 LDVF 期间 Epi 中的 VFR、动作电位持续时间（APD）和舒张间隔（DI）的分布。在 RV 和 LV 中均形成了跨壁 VFR 梯度，心内膜中的 VFR 更快。同时，Epi 中形成了较大的 VFR 梯度，RV-Sep 交界处的 VFR 最快，RV 居中，LV 最慢。光学映射显示在 LV 和 RV 内 VFR 分散性逐渐增加，在 LDVF 4-8 分钟后出现完全不可兴奋区域的镶嵌存在。在两个腔室中，LV 和 RV 内的 VFR 异质性均具有相似的幅度。在两个腔室中，在 LDVF 的所有时间点，VFR 的倒数与 DI 高度相关，但与 APD 无关。我们得出的结论是，在犬心脏中 LDVF 期间复杂的 VFR 梯度不能仅通过浦肯野纤维的分布来解释，而是与 LDVF 引起的电抑制的区域差异有关。
