Capturing the Influence of Conduction Velocity on Epicardial Activation Patterns Using Uncertainty Quantification

Abstract

Individual variability in parameter settings, due to either user selection or disease states, can impact accuracy when simulating the electrical behavior of the heart. Here, we aim to test the impact of inevitable uncertainty in conduction velocities (CVs) on the output of simulations of cardiac propagation, given three stimulus locations on the left ventricular (LV) free wall. To understand the role of physiological variability in CV in simulations of cardiac activation, we generated detailed maps of the variability in propagation simulations by implementing bi-ventricular activation simulations and quantified the effects by deploying robust uncertainty quantification techniques based on polynomial chaos expansion (PCE). PCE allows efficient stochastic exploration with reduced computational demand by utilizing an emulator for the underlying forward model. Our results suggest that CV within healthy physiological ranges plays a small role in the activation times across all stimulation locations. However, we noticed differences in variation coefficients depending on the stimulation site, i.e., LV endocardium, midmyocardium, and epicardium. We observed low levels of variation in activation times near the earliest activation sites, whereas there was higher variation toward the termination sites. These results suggest that CV variability can play a role when simulating healthy and diseased states.

Figure 1.

Uncertainty quantification of epicardial activation sequences. The top panel (A) shows the epicardial activation times for endocardial stimulation. The middle panel (B) shows the epicardial activation times for midmyocardial stimulation. The bottom panel (C) shows the epicardial activation times for epicardial stimulation. For each panel, the left column shows the mean activation sequence, the middle shows the standard deviation of the activation sequence, and the right shows the coefficient of variation of the activation sequence. In each panel, there are views from two perspectives, the left lateral and right lateral sides of the heart, respectively.