A rule-based method to model myocardial fiber orientation in cardiac biventricular geometries with outflow tracts

TL;DR

This paper introduces a new rule-based approach for modeling myocardial fiber orientation in both ventricles, including outflow tracts, improving the accuracy of cardiac simulations across different heart regions.

Contribution

A novel rule-based method models fiber orientation separately in each ventricle based on histological data, enhancing simulation accuracy in complex heart regions.

Findings

Accurately models fiber orientation in right ventricle and outflow tracts.

Simulations match clinical parameters in outflow tract arrhythmias.

Pipeline enables patient-specific electrophysiological modeling.

Abstract

Rule-based methods are often used for assigning fiber orientation to cardiac anatomical models. However, existing methods have been developed using data mostly from the left ventricle. As a consequence, fiber information obtained from rule-based methods often does not match histological data in other areas of the heart such as the right ventricle, having a negative impact in cardiac simulations beyond the left ventricle. In this work, we present a rule-based method where fiber orientation is separately modeled in each ventricle following observations from histology. This allows to create detailed fiber orientation in specific regions such as the endocardium of the right ventricle, the interventricular septum and the outflow tracts. We also carried out electrophysiological simulations involving these structures and with different fiber configurations. In particular, we built a modelling pipeline for creating patient-specific volumetric meshes of biventricular geometries, including the outflow tracts, and subsequently simulate the electrical wavefront propagation in outflow tract ventricular arrhythmias with different origins for the ectopic focus. The resulting simulations with the proposed rule-based method showed a very good agreement with clinical parameters such as the 10 ms isochrone ratio in a cohort of nine patients suffering from this type of arrhythmia. The developed modelling pipeline confirms its potential for an in silico identification of the site of origin in outflow tract ventricular arrhythmias before clinical intervention.