Asynchronous Pumping of a Pulsatile Ventricular Assist Device in a Pediatric Anastomosis Model

Background: Both pulsatile and continuous flow ventricular assist devices are being developed for pediatric congenital heart defect patients. Pulsatile devices are often operated asynchronously with the heart in either an “automatic” or a fixed beat rate mode. However, most studies have only investigated synchronized ejection. Methods: A previously validated viscoelastic blood solver is used to investigate the parameters of pulsatility, power loss, and graft failure in a pediatric aortic anastomosis model. Results: Pulsatility was highest with synchronized flow and lowest at a 90° phase shift. Power loss decreased at 90° and 180° phase shifts but increased at a 270° phase shift. Similar regions of potential intimal hyperplasia and graft failure were seen in all cases but with phase-shifted ejection leading to higher wall shear stress on the anastomotic floor and oscillatory shear index on the anastomotic toe. Conclusion: The ranges of pulsatility and hemodynamics that can result clinically using asynchronous pulsatile devices were investigated in a pediatric anastomosis model. These results, along with the different postoperative benefits of pump modulation, can be used to design an optimal weaning protocol.