A closed-loop multi-scale model of the cardiovascular system for evaluation of ventricular assist devices

Cardiovascular disease is the number one killer in America as well as most Westernized countries and is the primary cause of congestive heart failure. Over five million Americans are currently living with heart failure and over half a million more are diagnosed each year. Mechanical assist devices are used as a bridge to transplant and as destination therapy in people with severe heart failure. While these devices are highly engineered, their optimal implant configuration and settings have yet to be determined. A computational model has been developed in order to study the effect of these assist devices on the cardiovascular system. The model is multi-dimensional, making use of a quasi-one-dimensional arterial tree model for the systemic arteries coupled with lumped parameter models for the venous return and pulmonary circulation. In addition, a dynamic aortic valve model has been developed to account for the brief period of backflow at the onset of diastole and a complex impedance representation of the small arteries has been used as the outflow boundary condition to the arterial tree to account for phase-lag and wave reflection. The model produces physiologically consistent pressure and flow curves for both healthy and disease states, and preliminary validation has been performed against clinical data from patients under various levels of mechanical assist.