The Influence of Activation Time on Contraction Force of Myocardial Tissue: a Simulation Study

The efficiency of heart pump function greatly depends on synchronized contraction of myocardial muscle. In this work, contraction simulation of an excitable ventricular tissue cable was constructed to study the influence of excitation patterns on tissue contraction. The tissue cable is composed of elements which contract when excited by an external stimulus. In each calculation step, contraction force of each element is determined by a ventricular cell model. The mechanical deformation is then solved by finite element method and states of cells are updated accordingly. Several factors such as the starting position of the stimulation signal and the conduction velocity of gap-junctions affect contraction behavior. Simulation results show that the activation time, i.e. the time period the stimulation signal needs to spread over the tissue, is a dominant parameter for determining tissue contraction force. Contraction force of myocardial tissue increases monotonically with a decrease in activation time. This result suggests that minimization of activation time might be important for achieving effective tissue contraction