학술논문
Effects of Electroporation on the Transmembrane Potential Distribution in a Two-Dimensional Bidomain Model of Cardiac Tissue.
Document Type
Academic Journal
Author
Source
Subject
Language
English
ISSN
1045-3873
Abstract
Introduction: Defibrillation shocks, when delivered through internal electrodes, establish transmembrane potentials (Vm ) large enough to electroporate the membrane of cardiac cells. The effects of such shocks on the transmembrane potential distribution are investigated in a two-dimensional rectangular sheet of cardiac muscle modeled as a bidomain with unequal anisotropy ratios. Methods and Results: The membrane is represented by a capacitance Cm , a leakage conductance gb and a variable electroporation conductance G, whose rate of growth depends exponentially on the square of Vm . The stimulating current Io , 0.05.20 A/m, is delivered through a pair of electrodes placed 2 cm apart for stimulation along fibers and 1 cm apart for stimulation across fibers. Computer simulations reveal three categories of response to Io : (1) Weak Io , below 0.2 A/m, cause essentially no electroporation, and Vm increases proportionally to Io . (2) Strong Io , between 0.2 and 2.5 A/m, electroporate tissue under the physical electrode. Vm is no longer proportional to Io ; in the electroporated region, the growth of Vm is halted and in the region of reversed polarity (virtual electrode), the growth of Vm is accelerated. (3) Very strong Io , above 2.5 A/m, electroporate tissue under the physical and the virtual electrodes. The growth of Vm in all electroporated regions is halted, and a further increase of Io , increases both the extent of the electroporated regions and the electroporation conductance G. Conclusion: These results indicate that electroporation of the cardiac membrane plays an Important role in the distribution of Vm , induced by defibrillation strength shocks.