High-speed digital video imaging system to record cardiac action potentials

A new digital video imaging system was developed and its performance was evaluated to analyze the spiral wave dynamics during polymorphic ventricular tachycardia (PVT) with high spatio-temporal resolution (1 ms, 0.1 mm). The epicardial surface of isolated rabbit heart stained with di- 4-ANEPPS was illuminated by 72 high-power bluish-green light emitting diodes (BGLED: (lambda) 0 500 nm, 10mw). The emitted fluorescence image (256x256 pixels) passing through a long-pass filter ((lambda) c 660nm) was monitored by a high-speed digital video camera recorder (FASTCAM-Ultima- UV3, Photron) at 1125 fps. The data stored in DRAM were processed by PC for background subtraction. 2D images of excitation wave and single-pixel action potentials at target sites during PVT induced by DC shocks (S2: 10 ms, 20 V) were displayed for 4.5 s. The wave form quality is high enough to observe phase 0 upstroke and to identify repolarization timing. Membrane potentials at the center of spiral were characterized by double-peak or oscillatory depolarization. Singular points during PVT were obtained from isophase mapping. Our new digital video-BGLED system has an advantage over previous ones for more accurate and longer time action potential analysis during spiral wave reentry.