Estudo da propagação elétrica em fibras de Purkinje

Abstract

Purkinje fibers are fundamental structures in the process of propagation of the electrical stimulus of the heart. In order for contraction of the muscles of the ventricles to occur, these fibers need to stimulate the myocardium in a synchronized manner. However, certain changes in the properties of the cells composing these fibers may provide a desynchronization of the heart rate. This can occur through failures in the propagation of the electrical stimulus due to blockages occurring at the junctions that attach the Purkinje fibers to the ventricle muscle, so that this condition is considered a risk state for cardiac arrhythmias. However, obtaining the structure of Purkinje fibers from a specific patient is a difficult task and it is mandatory for studies involving the electrical activity of the heart. Most of these difficulties arise from the fact that the propagation velocity in the Purkinje fibers is extremely fast, ranging from 2 to 4 m/s, thus making experimental measurements a challenge. This work aims to investigate and analyze which properties may affect the propagation velocity and activation time in Purkinje fibers, such as cell geometry, conductivity, coupling of fibers with ventricular tissue and number of bifurcations in the network. In order to reach this goal, several Purkinje networks were generated by varying these parameters in order to perform a sensitivity analysis. For the implementation of the computational model was used the monodomain equations to describe mathematically the phenomenon. Two specific cellular models for Purkinje cells were used to model the ionic currents. The numerical solution was calculated using the Finite Volume Method. The results of the present work were in accordance with those obtained in the literature, so that the model was able to validate in a satisfactory way certain behaviors that occur in the conduction velocity and the activation time of the Purkinje fibers. In addition, the model was able to reproduce the characteristic delay on the propagation that occur at the Purkinje-Muscle-Junctions.