High resolution optical mapping of Na+ blocked ventricular tachycardia

A new digital video imaging system was developed and its performance to analyze the spiral wave dynamics during polymorphic ventricular tachycardia (PVT) with high spatiotemporal resolution was evaluated. The epicardial surface of isolated rabbit heart stained with di-4-ANEPPS was illuminated by 120-high-power bluish-green light emitting diodes (LED). The fluorescence image (256×256 pixels) passing though a long-pass filter (lc=600 nm) was monitored by a high-speed digital video camera recorder (DVCR) at 750 fps. 2D images of excitation wave and single-pixel action potentials at target sites during S2-induced spiral reentry were displayed for 10.9 s. The waveform quality is high enough to observe phase 0 upstroke and to identify repolarization timing. The effects of Na⁺ channel blockade was investigated by use of this system and the results suggest that Pilsicainide (3uM) caused the prolongation of the effective refractory period without affecting APD₉₀, which was associated with the magnify of excitable gap and longer VT cycle length. 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.