Bundle of His and Purkinje Fibers

The bundle of His transmits electrical impulses from the atrioventricular node to the ventricles of the heart. The bundle branches and divides into thin filaments, known as Purkinje fibers, that distribute the impulse to the ventricular muscle. Using the methodology described in Sahli et al., the Heart Model approximates representative geometry for the bundle of His and Purkinje fibers on the endocardial surface of the right and left ventricles.

The approximation uses the methodology described in Kotikanyadanam et al., where these structures are modeled as 1D electrical elements (DC1D2) with a uniform conductivity that exhibits higher conduction velocities than the surrounding cardiac tissue. The model couples the network to the myocardium at the terminus of the network branches. At the end of the network branches, single 1D electrical conduction (DC1D2) "resistor" elements are defined, and then the free end is tied to the myocardium. The resistors have the same uniform conduction properties as the ventricle. Bordas et al. describes this methodology for Purkinje-myocardium coupling.

The figure below shows the fiber (light green) and resistor (red) elements.

Bundle of His, Purkinje Fiber, and Resistor Elements