Purpose of Study:The recently published ASME standard: Assessing Credibility of Computational Modeling Through Verification and Validation: Application to Medical Devices (V&amp;V40) provides a risk-informed assessment framework to aid in regulatory evaluation of medical devices. The framework centers on determining model credibility from risk associated with decisions based on the computational model. This project aims to apply V&amp;V40 to a numerical model of the left ventricle (LV) during support with a LV assist device (LVAD), a therapy for patients with advanced heart failure. Despite improved survival, complications like thrombosis exist in 20% of cases. Flow in the heart involves complex fluid transport as well as the dynamical interactions between the incoming and residual flows which are drastically altered with LVAD support. Evidence suggests that the LV is a relevant site of thrombus formation and is related to intra-LV stagnation, which can be quantified with surrogate biomarkers computed from flow fields such as velocity, vorticity and pulsatility.&nbsp;Methods:A benchtop circulatory loop developed at San Diego State University that reproduces the dynamic flow patterns in the left ventricle (LV) of heart failure patients will be used in combination with a HeartMate II LVAD (Abbott, Inc). High-frequency pressure and flow signals are recorded while the time-varying flow field within a beating silicone LV is measured with particle image velocimetry (PIV). In these studies, a silicone LV supported by a HeartMate II LVAD was tested for an ejection fraction of 22% in combination with three LVAD speeds (0, 8k, and 11k rpm). A corresponding computational model was formulated with&nbsp;Alya&nbsp;software, a simulation code developed at Barcelona Supercomputing Center (BSC) designed to efficiently use large-scale computing facilities in multiscale multi-physics problems. Boundary conditions reflecting the measured pressure and LV geometry were used to solve the fluid dynamics problem. Heart valves are modeled through a pressure-driven porous medium and the LVAD through its H-Q performance curve.Summary of Results:The computational results closely reflect the major flow characteristics observed in the bench experiments. The pressure and flow predictions match the sensor measurements closely, with some oscillations in the response introduced by the valve models. The midplane velocity fields of the experimental and computational studies compared favorably, with a central LV vortex that grows during diastole and ejection through the apical LVAD cannula during systole. Quantitative comparison of vortex dynamics, residence time and shear activation potential will capture the uncertainty following V&amp;V40, a computationally expensive task but currently underway. Upon completion, the computational model is intended to predict biomarker stagnation which, in turn, will help during the regulatory process to accelerate the time-to-market of novel devices.

Complementing Regulatory Evidence Through Numerical Simulation Tests: An Application Case for Fluid Stagnation After Lvad Implantation

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.