Comparison of activation contour plots obtained using different models of activation.

<p>(A) Low PMJ density model, (B) high PMJ density model, and (C) instantaneous activation of the LV and RV endocardial surfaces.</p

Mahajan Cell Model Parameters.

<p>Mahajan cell model parameters used in the electrophysiology simulations. The description of each parameter is taken from Mahajan <i>et al.</i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114494#pone.0114494-Mahajan1" target="_blank">[25]</a></p><p>Mahajan Cell Model Parameters.</p

Six Lead ECG focusing on the QRS wave for non-boundary conforming (NBC) and boundary conforming (BC) models with mesh size .

<p>ECG computed using the boundary conforming model shows severe fractionation and incorrect R-wave progression.</p

Purkinje models.

<p>(A) Low and (B) high PMJ densities.</p

Apex-to-base and transmural gradients.

<p> and , conductance values.</p><p>Apex-to-base and transmural gradients.</p

Simulation Methods and Validation Criteria for Modeling Cardiac Ventricular Electrophysiology

<div><p>We describe a sequence of methods to produce a partial differential equation model of the electrical activation of the ventricles. In our framework, we incorporate the anatomy and cardiac microstructure obtained from magnetic resonance imaging and diffusion tensor imaging of a New Zealand White rabbit, the Purkinje structure and the Purkinje-muscle junctions, and an electrophysiologically accurate model of the ventricular myocytes and tissue, which includes transmural and apex-to-base gradients of action potential characteristics. We solve the electrophysiology governing equations using the finite element method and compute both a 6-lead precordial electrocardiogram (ECG) and the activation wavefronts over time. We are particularly concerned with the validation of the various methods used in our model and, in this regard, propose a series of validation criteria that we consider essential. These include producing a physiologically accurate ECG, a correct ventricular activation sequence, and the inducibility of ventricular fibrillation. Among other components, we conclude that a Purkinje geometry with a high density of Purkinje muscle junctions covering the right and left ventricular endocardial surfaces as well as transmural and apex-to-base gradients in action potential characteristics are necessary to produce ECGs and time activation plots that agree with physiological observations.</p></div

Action Potential (AP) plots of the Purkinje and normal UCLA cell model (Apex/Epi).

<p>The Purkinje AP shows a high upstroke velocity, a prominent early rapid repolarization, a negative plateau potential, an increased action potential duration, and spontaneous diastolic depolarization.</p

Tensor field and finite element mesh.

<p>(A) Short-axis slice of the linear invariant interpolated tensor field superposed on a coarsened surface mesh. (B) Hexahedral finite element mesh. The stair-stepped nature of the mesh is shown in the zoomed-in view of the model.</p

Sustained wave breakup and chaotic meandering during simulated Ventricular Fibrillation (VF).

<p>VF was induced using an S1-S2 protocol with the second stimulus applied between and . The voltage contour plot is shown at .</p

6-lead electrocardiogram of a normal adolescent White New Zealand male rabbit.

<p>The following defining aspects of the ECG are visible (5th validation criteria): fast QRS upstroke, no QRS fractionation, R-wave progressions from V1 to V6, positive T wave with longer upstroke than downstroke.</p