Effects of the Purkinje System and Cardiac Geometry on Biventricular Pacing: A Model Study

Abstract

Abstract-Heart failure leads to gross cardiac structural changes. While cardiac resynchronization therapy (CRT) is a recognized treatment for restoring synchronous activation, it is not clear how changes in cardiac shape and size affect the electrical pacing therapy. This study used a human heart computer model which incorporated anatomical structures such as myofiber orientation and a Purkinje system (PS) to study how pacing affected failing hearts. The PS was modeled as a tree structure that reproduced its retrograde activation feature. In addition to a normal geometry, two cardiomyopathies were modeled: dilatation and hypertrophy.A biventricular pacing protocol was tested in the context of atrio-ventricular block. The contribution of the PS was examined by removing it, as well as by increasing endocardial conductivity. Results showed that retrograde conduction into the PS was a determining factor for achieving intraventricular synchrony. Omission of the PS led to an overestimate of the degree of electrical dyssynchrony while assessing CRT. The activation patterns for the three geometries showed local changes in the order of activation of the lateral wall in response to the same pacing strategy. These factors should be carefully considered when determining lead placement and optimizing device parameters in clinical practice.

A coupled 3D–1D numerical monodomain solver for cardiac electrical activation in the myocardium with detailed Purkinje network

“…In this section we propose an algorithm for the numerical solution of the MM coupled problem (10). In particular, in Section 3.1 we first introduce the time discretization followed by a fixed point algorithm, whose convergence analysis is carried out in Section 3.2.…”

“…In this regard, different coupled models have been considered in the literature. We cite the coupled eikonal/eikonal model [13,5,6,8] (the first model refers to the one used for the network, whereas the second to the one used for the myocardium), the eikonal/monodomain model [4], the monodomain/bidomain model [9], the monodomain/monodomain model [10], and the bidomain/bidomain model [11,12]. When monodomain or bidomain models are considered, the issue of the coupling between cardiac muscle and Purkinje network should be properly addressed.…”

“…We cite for example the eikonal model [4,5,6,8], the monodomain model [9,10], and the bidomain model [11,12]. In normal electrical propagation, the electrical signal, originating from the atrioventricular (AV) node, travels along this network and enters the ventricular muscle through the Purkinje-muscle junctions (PMJ).…”

euHeart: personalized and integrated cardiac care using patient-specific cardiovascular modelling

“…Complementing these tetrahedral meshes, warping techniques have been developed [26] in order to generate high-order patientspecific hexahedral meshes, suitable for mechanical simulations. Finally, these volumetric meshes are further augmented by synthetically adding substructural information relevant for CRT, such as myocardial fibre orientation or the Purkinje system [27], which are boundary conditions significantly changing the outcome of the simulations.…”

Cardiovascular Mechanics

“…In comparison, a fairly small number of studies employed organ level models of ventricular cardiac mechanics, and, even less frequent, models of ventricular electromechanics. In most of the cardiac organ level mechanics studies researchers resorted to simplifications by using electrical-only models to predict effects on mechanical performance [112], by employing simplified models of cellular dynamics [75,113] and active tension [114], by simplified representation of organ geometry [113,115] and by neglecting orthotropic properties of tissue structure [75,113] and, finally, by largely neglecting the impact of pathological alterations onto ventricular electromechanics, although execptions do exist [116]. Evidence of the progress made in the field of computational modeling is the introduction of models into clinical application as an additional modality which supports clinical decisions in treating ischemic heart disease [117], the assessment of effects of heart surgery [118] and ventricular pacing [114,116,119].…”