An Integrated Heart–torso Electromechanical Model for the Simulation of Electrophysiological Outputs Accounting for Myocardial Deformation

When generating in-silico clinical electrophysiological outputs, such aselectrocardiograms (ECGs) and body surface potential maps (BSPMs), mathematicalmodels have relied on single physics, i.e. of the cardiac electrophysiology(EP), neglecting the role of the heart motion. Since the heart is the mostpowerful source of electrical activity in the human body, its motiondynamically shifts the position of the principal electrical sources in thetorso, influencing electrical potential distribution and potentially alteringthe EP outputs. In this work, we propose a computational model for thesimulation of ECGs and BSPMs by coupling a cardiac electromechanical model witha model that simulates the propagation of the EP signal in the torso, thanks toa flexible numerical approach, that simulates the torso domain deformationinduced by the myocardial displacement. Our model accounts for the majormechano-electrical feedbacks, along with unidirectional displacement andpotential couplings from the heart to the surrounding body. For the numericaldiscretization, we employ a versatile intergrid transfer operator that allowsfor the use of different Finite Element spaces to be used in the cardiac andtorso domains. Our numerical results are obtained on a realistic 3Dbiventricular-torso geometry, and cover both cases of sinus rhythm andventricular tachycardia (VT), solving both the electromechanical-torso model indynamical domains, and the classical electrophysiology-torso model in staticdomains. By comparing standard 12-lead ECG and BSPMs, we highlight thenon-negligible effects of the myocardial contraction on the EP-outputs,especially in pathological conditions, such as the VT.