OPTICAL MAPPING SYSTEM WITH DUAL HIGH SPEED VIDEO CAMERAS FOR OBSERVATION OF THREE DIMENSIONAL CARDIAC EXCITATION PROPAGATION DURING ARRHYTHMIA

光学成像已被广泛用于研究室性心律失常（如心室颤动和室性心动过速）的诱导和终止机制，这是心源性猝死的测量原因。在本研究中，我们研制了一种新型的心脏兴奋光学成像系统，该系统具有以下功能：(1)该系统使用两台高速数字摄像机，可以在心脏表面更大范围内监测心脏兴奋。它能以较高的时间和空间分辨率跟踪显示蜿蜒的可重入活动。(2)该系统考虑了心脏的三维形状，可以准确地评估传导速度和波前曲率等传导参数。(3)该系统可以通过图像处理提取心脏兴奋传播的波前或波后的方向和速度。这种图像分析方法是开发自适应电刺激系统的基础，该系统可以根据心脏的实际兴奋情况在任意位置和任意时间相位进行电刺激。(4)系统配有透明电极模块的电刺激装置，可观察刺激电极附近的心脏兴奋情况。该系统可以在刺激后立即监测刺激点电极附近的虚拟电极极化现象，具有比以往报道的系统更高的时间和空间分辨率。(5)该系统可以实时识别心脏表面某一点心脏组织的特定复极化相，并根据该复极化相识别传递电刺激。这些工程成果使新的实验方法的发展，可应用于心律失常的研究。

Optical mapping has been widely used to investigate the mechanism of induction and termination of cardiac arrhythmia such as ventricular fibrillation and ventricular tachycardia, that are measure causes of sudden cardiac death. In this study, we have the new optical mapping system of cardiac excitation having the following functions :(1)The system can monitor cardiac excitation in wider area of the cardiac surface using two high speed digital video cameras.It can track reentrant activities showing meandering with high temporal and spatial resolution.(2)The system takes three dimensional shape of the heart into consideration to evaluate accurately conduction parameters such as conduction velocity and curvature of wave-front.(3)The system can extract the direction and velocity of wave front or wave-back of the cardiac excitation propagation by means of image processing. This image analysis method is basis for development of adaptive electrical stimulation system that can deliver electric stimuli on arbitrary position and arbitrary time phase depending on the actual cardiac excitation.(4)The system is equipped with electrical stimulation device with transparent electrode module that enables observation of cardiac excitation near the stimulation electrode. The system can monitor virtual electrode polarization phenomena near the stimulation point electrode immediate after the application of the stimuli with higher temporal and spatial resolution than previously reported systems can(5)The system can identify the specific repolarization phase of cardiac tissue at a certain point on cardiac surface in real time, and can deliver the electric stimuli depending on this repolarization phase identification.These engineering achievements enable development of new experimental methodologies that can be applied to cardiac arrhythmia research.