DIRECT ACTIVATION AND DEFIBRILLATION OF CARDIAC TISSUE

It is shown that inhomogeneity due to gap junctional resistance allows an excitable cable to be directly activated or defibrillated by the a pplication of a large amplitude point stimulus of short duration. Mult iple-scale analysis is used to derive a model equation describing the response of the excitable medium to stimuli, and this equation is anal yzed to give quantitative estimates of the direct stimulus threshold a nd the defibrillation threshold. These estimates are shown to be in go od agreement with experimental findings. (C) 1996 Academic Press Limit ed