The lack of an appropriate three-dimensional constitutive relation for stress in passive ventricular myocardium currently limits the utility of existing mathematical models for experimental and clinical applications. Previous experiments used to estimate parameters in three-dimensional constitutive relations, such as biaxial testing of excised myocardial sheets or passive inflation of the isola...

OBJECTIVES Prior studies demonstrated marked electrophysiological and pharmacological differences between canine ventricular epicardium and endocardium. For atrium, however, it has been assumed that, because of the thin wall, electrical properties of epicardium and endocardium are similar. The aim of the present study was to compare the action potential (AP) characteristics in epicardial and en...

BACKGROUND The mechanisms that maintain long duration ventricular fibrillation (LDVF) are unclear. The difference in distribution of the Purkinje system in dogs and pigs was explored to determine if Purkinje activation propagates to stimulate working myocardium (WM) during LDVF and WM pacing. METHODS AND RESULTS In-vivo extracellular recordings were made from 1044 intramural plunge and epicar...

Recurrence rates following ablation for persistent AF (psAF) remain high with the underlying mechanisms complex and poorly understood. Asynchronous activation of endocardial epicardial surfaces during AF, defined as endo-epicardial dissociation (EED) may be a driver AF. We aim to investigate whether using novel vector mapping approach, Stochastic Trajectory Analysis Ranked (STAR) signals, endo-...