D. W. Frazier

TL;DR: The hypothesis was tested that the field of a premature (S2) stimulus, interacting with relatively refractory tissue, can create unidirectional block and reentry in the absence of nonuniform dispersion of recovery when S2 field strengths and tissue refractoriness are uniformally dispersed at an angle to each other.

TL;DR: In this paper, the authors show that ventricular fibrillation and repetitive responses induced electrically with S1 and S2 stimuli at different ventricular sites arise by figure-of-eight reentry, and this reentry is caused by the ability of S2 stimulation both to prolong refractoriness near the S2 site and to initiate a propagated response in the region between the S 1 and S 2 sites.

TL;DR: Defibrillation fields created by small epicardial electrodes are very uneven and achievement of a certain minimum potential gradient over both ventricles is necessary for ventricular defibrillation; the difference in shock strengths required to achieve this minimum gradient overBoth ventricle may explain the differences in DIFTs for various electrode configurations.

TL;DR: In six open-chest dogs, simultaneous recordings were made from 120 transmural electrodes in 40 plunge electrodes within a 35 X 20 X 5-mm portion of the right ventricular outflow tract during epicardial and endocardial pacing, and it is concluded that the initial spread of activation is helicoid and determined by transmural fiber direction.

TL;DR: For stimulation during electrical diastole, both current density magnitude and longitudinal and transverse components of the potential gradient are closely correlated with excitation, and the extracellular potential gradient along cardiac cells has a lower threshold than across cells, while current density thresholds along and across cells are similar.