Fluid–Structure Interaction Models of Bioprosthetic Heart Valve Dynamics in an Experimental Pulse Duplicator

Abstract

Computer modeling and simulation is a powerful tool for assessing the performance of medical devices such as bioprosthetic heart valves (BHVs) that promises to accelerate device design and regulation. This study describes work to develop dynamic computer models of BHVs in the aortic test section of an experimental pulse-duplicator platform that is used in academia, industry, and regulatory agencies to assess BHV performance. These computational models are based on a hyperelastic finite element extension of the immersed boundary method for fluid–structure interaction (FSI). We focus on porcine tissue and bovine pericardial BHVs, which are commonly used in surgical valve replacement. We compare our numerical simulations to experimental data from two similar pulse duplicators, including a commercial ViVitro system and a custom platform related to the ViVitro pulse duplicator. Excellent agreement is demonstrated between the computational and experimental results for bulk flow rates, pressures, valve open areas, and the timing of valve opening and closure in conditions commonly used to assess BHV performance. In addition, reasonable agreement is demonstrated for quantitative measures of leaflet kinematics under these same conditions. This work represents a step towards the experimental validation of this FSI modeling platform for evaluating BHVs.

Violin plot data: A concerto of crucial information on valve thrombogenicity categorized in vitro by valve motion and inferred flow velocity

“…An extensively cited commercial in vitro test system [3,[5][6][7][8][9] was used with typical simulation conditions including pulse rate 70 cycles/min; pressures ca.120/80 mmHg (millimeters of mercury); and cardiac output 5 litres/min. Basic test methodology is depicted in Figure 1.…”

“…The Leonardo modified pulse duplicator originally adapted in 2011 with innovative features to measure PDVA from backlit valves remains in current use with improved spatial and temporal resolution capability (i.e., 0.001 centimeter 2 and 1 microsecond). Valves tested in this system were recently compared to numerical simulations for contemporary porcine tissue and bovine pericardial bioprosthetic heart-valves and also with data from a similar independent pulse duplicator with excellent conformity [3].…”

“…A visco-elastic impedance adapter (VIA) models bulk ventricular visco-elasticity to produce physiological isovolumetric functionality has been utilized in several previous studies [3,[6][7][8][9][10]. Jennings et al [13] in their use of the Leeds in vitro valve tester to study stentless porcine valves found VIA advantageous in ameliorating unphysiological left-ventricular pressure oscillations.…”

“…Ventricular visco-elasticity associates with valve opening and closure dynamics, ventricular pressure rates (dp/dt), propensity for microbubbles, high intensity trancranial signals (HITS), cavitation, acoustic emissions, and vortex flow formations. Recently, Lee et al [3] characterized VIA as a three-element Windkessel and utilized in fluid-structure interaction models of bioprosthetic heart valve dynamics. These models were validated with an experimental pulse duplicator.…”

“…More recently, computational methods employed to examine flow patterns, flow velocities, and pressures associated with contemporary mechanical and bioprosthetic valve function have generated extensive information on flow but as yet have not proposed a development pathway to eliminate thrombogenicity in the former and extend durability in the latter [e.g. [2][3][4].…”