Effects of Purkinje Fiber Conduction Block on Cardiac Pump Function: Computational Modeling Study

Background and Objectives: Cardiac and hemodynamic conditions such as myocardial infarction, cardiomyopathy, hypertension, and aortic valve disease can impair conduction in the Purkinje fiber network system that may lead to a reduction in left ventricle (LV) pump function. Methods: In this study, we developed a computational modeling framework that couples electrical propagation in an anatomically realistic Purkinje fiber network and electromechanics in the LV to determine the effects of conduction abnormalities on LV pump function. The framework was first used to establish a baseline case where the activation time and cardiac pump function indices are comparable to those measured in a healthy human. Subsequently, the framework was used to simulate conduction blocks occurring in different locations of the Purkinje fiber network. Results: The simulation results show that the cardiac pump function is dependent on the location of the block, where a left bundle branch block (LBBB) in the Purkinje fiber network produces the greatest reduction in ejection fraction (EF) (59% to 46%) and peak pressure (119 to 97 mmHg) followed by a left anterior fascicles block (LAFB), where EF is slightly reduced to 58% and peak pressure is reduced from 119 to 112 mmHg. By consolidating the simulation results, we also establish an exponential relationship between cardiac pump function indexed by the myocardial strain and EF with myocardial activation time and the systolic dyssynchrony index (SDI). Conclusion: The simulations predict a threshold where beyond an activation time of 240 [ms] and SDI of 8.4%, myocardial strain and EF are reduced by more than 5% compared to the baseline case.