Method of backflow reduction in ventricular assist devices.

Ventricular assist devices (VADs) have been developed to augment the deteriorating heart function of those suffering from end-stage congestive heart failure. While these devices have the potential to extend the life span and improve the quality of life of their recipients, they are also susceptible to mechanical failure. In the case of many known VADs, pump failure allows blood to flow retrograde through the device leading to a rapid loss of systemic pressure and loss of life. Some devices, such as heart valves, have been implemented to reduce or eliminate the potential for backflow in VADs but almost always at the expense of making the system more prone to thromboembolism or less reliable overall. This study presents a novel method of reducing backflow in a stopped VAD without significantly increasing the risk of thromboembolism or failure of the system. A combination of computational analysis and experimental testing was used for this study. The device design was evaluated with the extensive use of CFD and fluid-solid interaction modeling for predicting thrombus initiation potentials and mechanical and fluid stresses within the device. These results were then used in an optimization loop to parametrically evaluate the design geometry. Mock-loop experiments with a prototype provided validation of the CFD calculations. Additionally, the device design was evaluated for manufacturability with blood compatible materials and suitable surfacing techniques. The CFD numerical estimations generally agree with the experimental measurements over the entire range of backflow situations tested. Streamline analysis reveals no recirculation regions within the device. Velocity and residence time plots also demonstrated low indicators for thrombosis. Initial prototype tests validate the working principle of the device.