Graded effects of pulsed electric fields on contractility of single heart cells

Abstract

The effects of high-intensity electric fields on excitability and contractility of the heart at the cellular level are pertinent to defibrillation and electrical ablation. Stimulation of single cardiac cells with a rectangular pulsed electric field elicits twitch contraction. Variation of the stimulus intensity and duration shows a distinct strength-duration curve for the threshold of excitation, T1. T1 is mediated by the cell orientation with respect to the electric field (parallel or perpendicular). Above the threshold level is a second threshold level, T2, for cellular contracture. T2 has a shape similar to that of T1, and may be a consequence of formation of pores in the cell membrane (electroporation).<>