A model of gap junction conductance and ventricular tachyarrhythmia

Cardiac gap junctions (GJs) form low resistance pathways along which the electrical impulse flows rapidly and repeatedly between all the cells of the myocardium, enabling coordinated contraction of the heart. In many heart diseases, electrical coupling through GJ channels between cardiomyocytes is down regulated. We set up a mathematical model of a chain of myocardial fibers to study how changing the coupling affects the activity of autorhythmic myocytes. While uncoupling blocked the propagation of excitation from autorhythmic myocytes to surrounding quiescent but excitable cells, different degrees of uncoupling increased the automaticity of the cells. Our modeling data suggests that the number of autorhythmic cells plays a key role in the excitation of autorhythmic cells and the conduction of impulses. We conclude that the degree of uncoupling between cardiomyocytes, induced by pathological processes, may generate ectopic foci, tachyarrhythmias being the outcome.