Electrical behavior of defibrillation and pacing electrodes

This article discusses the electrodes and their interfaces for internal and external defibrillation and external pacing applications. Of primary concern is the nature of the current delivery and distribution at the electrode-tissue interface and the techniques that may be used to generate a uniform distribution of current density in order to minimize pain and burning. The cost of achieving a uniform current distribution is tolerable for external pacing applications, but questionable for defibrillation applications. In the process of examining the nature of the electrode interface, we also discuss various models of its behavior, including analytic, equivalent circuit, numerical, and empirical models.