To realize an accurate cardiovascular dynamics simulation that represents the change in blood pressure and blood flow in the left ventricle (LV) and blood vessels, it is necessary to provide the left ventricular model and circulation model together with a coupling calculation algorithm of both models. Previous studies have employed a time-varying elastance model in which a coupling calculation with a circulation model is easy to realize. However, there has been a problem that it is difficult to simulate heart disease caused by damage to ventricular cell functions. On the other hand, the LV mechanical model, which uses a relationship between the shape and contraction force of myocardial cells such as the finite element method (FEM), is effective to analyze various aspects of cardiovascular dynamics. However, since the FEM-based LV mechanical model requires convergence calculation, it is not easy to exchange circulation models to be coupled. In this study, we propose a flexible simulation system by which the simulation models can be easily exchanged. The system is constructed with independent simulators for a left ventricular mechanical model and a circulation model. We have realized a coupling calculation algorithm that is capable of calculating cardiovascular dynamics from these two models.