In both experimental
and computational vulnerability studies, an electrically quiescent
post-shock period termed the isoelectric window (IW) has been
observed followed by a focal activation. While the mechanisms
underlying the origination of this post-shock activation remain unclear,
we have recently suggested that virtual electrode polarization (VEP)-induced
graded responses play an important role in its origination.
The goal of this study is to characterize the relationship between the time of onset of the
global post-shock activations and the tissue preshock state, and to provide a clear
understanding of the mechanisms governing this relationship. To do so, the
transmembrane potential in an isolated sheep right ventricle was imaged
optically on both the endo- and epicardial surfaces immediately before, throughout,
and after a shock.
