In vitro simulation of mitral valve therapies

Mitral regurgitation (MR) is the most frequent valvular heart disease. One main cause of MR is abnormal papillary muscle (PM) displacement. Due to the limitations of previous aetiology studies, available therapies are often sub-optimal. In vitro simulation methods can aid in MR aetiology study, and new and existing therapy development. The aim of this work is to develop an in vitro platform including all mitral valve (MV) components and a flexible beating mock left ventricle made of silicone, for aetiology studies and MR therapy assessment. A novel in vitro simulation test rig has been developed to allow the positioning of animal MVs into a cardiovascular hydrodynamic testing system (ViVitro System, ViVitro Labs, Inc., Canada), and the control of MV sub-components. Functions of 3 MVs are measured at different PM positions, both at rest and during exercise. The system was also used to assess novel repair and replacement technologies. Results have shown that the MV functions are most sensitive to a specific form of PM displacement, associated with PM movements in the base-apical direction. The safe region of PM positions has been identified, which may serve as a benchmark and a potential guide for clinical corrections. Exercise has shown not to exacerbate MR fraction at any PM position, so exercise-induced MR appears not to be directly related to PM displacements. At a few PM positions, exercise caused MR volume per minute to reduce. The test rig can be used as a surgery rehearsal platform to enhance surgical outcome. A novel leaflet extension device and the prototype of a transcatheter MV replacement have both been tested in the test rig and implant displacement observed has been feedback for device improvement. A lab-made MV was tested as a promising approach to achieve customised generalised MV geometry