心筋局所冷却と低電圧DCショックによるスパイラル・リエントリーの制御

抄録

Cooling of myocardial tissue destabilizes spiral wave reentry through a prolongation of the action potential and a decrease in conduction velocity. We have recently demonstrated that moderate regional myocardial cooling (by ∼5°C) causes a significant decrease in the intensity of DC shocks required to terminate spiral wave reentry in the rabbit ventricle (Heart Rhythm 2006). In this study, we have investigated its underlying mechanisms in 2-dimensional rabbit ventricular myocardium by using high-resolution optical mapping. Application of high-intensity shocks caused an immediate termination of spiral wave reentry through a phase-resetting mechanism (mode-1 termination) regardless of absence or presence of regional cooling. Moderate-intensity DC shocks created multiple phase singularities and interactions of these shock-induced singularities with the stationary spiral wave (rotor) often resulted in delayed termination of reentry through unpinning of the rotor (mode-2 termination). In the presence of regional cooling, the mode-2 termination of spiral waves occurred with lower-intensity DC shocks. These results suggest that appropriate regional myocardial cooling facilitates DC shock-induced termination of spiral wave reentry through unpinning of rotors in the ventricular myocardium. [J Physiol Sci. 2008;58 Suppl:S178]