Dynamic Left Atrioventricular Phantom Test Bed Emulating Mitral Valve Motion

Abstract

Novel catheter-based medical procedures targeting heart valve structures are currently under development. These techniques entail installing a prosthetic implant on valves inside a beating heart. The development of these approaches requires a simple and effective validation test bed. Current early process testing methods rely on both static and dynamically pressurized excised porcine hearts. The variability between excised-tissue mechanical properties poses problems of reproducibility. In addition, these test beds do not emulate annulus motion, which affects the implant installation. A reproducible phantom of the left atrioventricular chambers was developed. The system consists of a hydraulic constant flow arrangement and a polyvinyl alcohol phantom heart with material properties that mimic passive myocardium mechanical properties and annulus motion. The system was then used to emulate blood flow through an actual heart. The building process starts by obtaining an accurate computer-aided design (CAD) model of a human heart, from which, a mold is produced using a novel rapid-freezing prototyping method and computer numerical control machining. The phantom is then cast-out of polyvinyl alcohol (PVA), a hydrogel, whose mechanical properties are set by subjecting the phantom to freeze and thaw cycles. Subsequently, blood flow is emulated at a constant volumetric rate at the atrial pressure observed in a healthy adult human heart at rest. The annulus motion is implemented by suturing the outside of the phantom to a one-degree-of-freedom cam-follower mechanism reproducing valve motion. Such test beds could play a significant role in future development of medical devices.