The role restitution in pacing induced spiral wave acceleration.

Attempts to terminate monomorphic tachycardia by rapid pacing occasionally lead to acceleration of the tachycardia rate followed by fibrillation. Previous experimental studies have shown that rapid pacing can convert a single-wave functional reentry into a stable multi-wave reentry with accelerated rate, but only when the single spiral rate is significantly lower than the rate the tissue can sustain. In addition the acceleration was facilitated by broad and deep conduction velocity restitution. This study explores the mechanisms that modulate the potential for and degree of acceleration. Results demonstrate that ionic changes that affect CV restitution and increase core size of the functional reentry facilitate acceleration by wave multiplication. Understanding the mechanisms for reentry acceleration may yield new strategies that prevent the degeneration of tachycardia to fibrillation.