RESUMEN
OBJECTIVES: The objective of this study was to evaluate the haemodynamic performance of transcatheter mitral valve replacement (TMVR) Implant with a focus on turbulence and washout adjacent to the ventricular surface of the leaflets. TMVR holds the promise of treating a large spectrum of mitral valve diseases. However, the haemodynamic performance and flow dynamics of such replacements are not fully understood. METHODS: A tri-leaflet biopsrosthetic TMVR represented by Caisson implant of size 36A was implanted in the mitral position of a left heart simulator pulse duplicating system under physiological conditions. The 36A implant covers an anterior-posterior range of 26-32 mm and a commissure-to-commissure range of 30-36 mm. Transmitral pressure gradient, effective orifice area and regurgitant fraction were calculated. Particle image velocimetry was performed to evaluate turbulence in 2 perpendicular planes (Reynolds and viscous shear stresses, respectively). Additionally, dye experiments were performed to visualize washout. RESULTS: Transmitral pressure gradient was 1.29 ± 0.27 mmHg and effective orifice area was 2.96 ± 0.28 cm2. Regurgitant fraction was 14.13 ± 0.08%. Total washout was 4.27 cardiac cycles. Largest viscous shear stress reaches 3.7 Pa and 2.4 Pa in ventricle and atrium, respectively. Reynolds shear stress in the atrial side was <10 Pa. In the ventricular side, the largest Reynolds shear stress reached â¼35 Pa. CONCLUSIONS: TMVR leads to favourable haemodynamics with low degree of turbulence combined with fast washout around the leaflets indicating promising potential for freedom from blood damage potential and thrombosis corroborated by initial clinical studies as part of the valves's Early Feasibility Study.
Asunto(s)
Enfermedades de las Válvulas Cardíacas , Implantación de Prótesis de Válvulas Cardíacas , Prótesis Valvulares Cardíacas , Insuficiencia de la Válvula Mitral , Cateterismo Cardíaco , Enfermedades de las Válvulas Cardíacas/cirugía , Humanos , Válvula Mitral/diagnóstico por imagen , Válvula Mitral/cirugía , Insuficiencia de la Válvula Mitral/diagnóstico por imagen , Insuficiencia de la Válvula Mitral/cirugía , Resultado del TratamientoRESUMEN
Transcatheter Mitral Valve Replacement (TMVR) is currently under clinical investigation as a viable treatment option for mitral regurgitation (MR). Therefore, it is important to outline the key functional requirements of a TMVR prosthesis in order to provide an overall approach to assessing mitral valve replacement devices utilizing a combination of in vitro and preclinical methods. This article provides a review of the mitral valve disease as well as general considerations and guidance for developing a TMVR device based on International Industry Standards. Specific details pertaining to the mitral valve apparatus, morphology of mitral valve disease, assessment of specific patient population as well as hazard analysis to evaluate and develop a TMVR device to treat a specific patient population have been included. The details contained within this report are not all inclusive or explicate for every technology being developed but rather thought of as a general guide on how a TMVR technology could be developed in alignment with International Industry Standards. Key learnings from the Transcatheter Aortic Valve Replacement (TAVR) experience has also been considered and taken into account when outlining this general guidance for TMVR. Key learning points from the TAVR development experience included the following: quantification of acceptable levels of paravalvular leak, valve migration potential using various anchoring methods and overall implant frame failure modes when treating the native aortic valve. It should be noted that TAVR is over a decade further along in development and clinical experience compared to TMVR. These key learnings from the early experience with TAVR should be considered with all transcatheter development projects.