In Vitro Analysis of Left Ventricular Assist Device Outflow Graft Orientations and Their Effect on Aortic Hemodynamics

Continuous-flow left ventricular assist devices have become an important treatment option for patients with advanced heart failure. However, adverse hemodynamic effects as consequence of an altered blood flow within the aorta and the aortic root remain a topic of concern. In this work, we investigated the influence of the outflow graft orientation on the hemodynamic profile and flow parameters within the thoracic aorta. Aortic models with different outflow graft orientations were designed and three-dimensional (3D) printed to mimic common implantation configurations and were integrated into a pulsatile mock circulatory flow loop. Assist device function was achieved using a rotary pump, replicating nonpulsatile, continuous support flows of 1-5 L/min. Flow velocity, wall shear stress, and pressure gradients were investigated for each configuration using sonography and four-dimensional (4D) flow magnetic resonance imaging. Mean wall shear stresses measured in 4D flow software were lowest for a graft inclination angle of 45°. Streamline visualization revealed areas of nonuniform, retrograde, and vortex flow in all models but most prominent for the aortic model with an outflow graft inclination of 60°. The insights gained from this research may aid in understanding clinical outcomes following assist device implantation and long-term mechanical circulatory support.