Mechanisms and pharmacological control of ventricular spiral-wave reentry

我们使用我们独创的具有高时空分辨率的光学标测系统，分析了体外灌流的兔心脏中螺旋波折返的动力学。本系统具有较高的时空分辨率(0.1 mm和1.3ms)和信号质量(S/N比10.6)和较少的光漂白(2.4%/min)，使我们能够分析心脏快速性心律失常时螺旋波动力学的细节。应用自行研制的高分辨率光学标测系统，研究了室性心动过速(VT)时，在二维各向异性心外膜下层中螺旋折返的动力学和药理调节。交叉场刺激诱发的室性心动过速多由单环r-…引起更多的条目围绕着功能线的区块。功能性阻滞线是由螺旋尖沿其自身的不应性阻滞线(不应性阻滞线)蜿蜒，并在中心不应性阻滞线(传导阻滞线)两端的枢轴点上出现明显的传导延迟而形成的。后者总是平行于心外膜下纤维方向。动作电位之间没有等电段(完全可兴奋的间隙)，在中央不应性阻滞线获得低幅度双电位。用匹西卡胺或异丙吡胺阻断Na~+通道后，枢点的传导延迟明显增加，功能性传导阻滞线延长。在枢轴点周围，动作电位上升缓慢，持续时间长，转身后动作电位正常，可兴奋间隙短。这些结果表明，二维脑室螺旋折返的动力学主要取决于(1)波前的曲率，(2)组织的各向异性和(3)波前-尾部的相互作用。较少

We have analyzed dynamics of spiral-wave reentry in rabbit hearts perfused in-vitro using our original optical mapping system with a high spatio-temporal resolution.1. Development of a new optical mapping system using a high-speed digital video camera combined with light-emitting diodes.This system has an advantage over ones reported previously by other investigators in terms of high spatio-temporal resolutions (0.1 mm and 1.3 ms) and signal quality (S/N ratio 10.6) combined with less photo-bleaching (2.4%/min), and this system enables us to analyze the detail of the spiral-wave dynamics during cardiac tachyarrhythmias.2. Analysis of ventricular spiral dynamicsDynamics and pharmacological modulation of spiral reentry during ventricular tachycardia (VT) was investigated in a two-dimensional anisotropic subepicardial layer of rabbit ventricular myocardium by use of our original high-resolution optical mapping system. VT induced by cross-field stimulation was often caused by single-loop r … More eentry around a functional line of block. The functional block line was formed by meandering of the spiral tip along its own refractory tail (refractory block line) combined with pronounced conduction delay at the pivot points around the both ends of the central refractory block line (conduction block). The latter was always oriented parallel to the subepicardial fiber direction. There was no isoelectric segment (fully-excitable gap) between action potentials, and low-amplitude double potentials were obtained at the central refractory block line. Blockade of Na^+ channels by pilsicainide or disopyramide markedly enhanced conduction delay at the pivot points resulting in a prolongation of the functional conduction block line. Around the pivot points, the action potentials showed slow upstroke and long duration, but after making a turn, normal action potentials with a short excitable gap were observed. These results suggest that dynamics of two-dimensional ventricular spiral reentry is determined primarily by (1) the curvature of a wavefront, (2) tissue anisotropy and (3) the wavefront-tail interaction. Less