Radiofrequency Ablation Alters the Microstructural Organization of Healthy and Enzymatically Digested Porcine Mitral Val
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SP ISS: EXPERIMENTAL ADVANCES IN CARDIOVASCULAR BIOMECHANICS
Radiofrequency Ablation Alters the Microstructural Organization of Healthy and Enzymatically Digested Porcine Mitral Valves J.M. Bender 1 & W.R. Adams 1 & A. Mahadevan-Jansen 1 & W.D. Merryman 1 & M.R. Bersi 1 Received: 30 January 2020 / Revised: 20 August 2020 / Accepted: 25 August 2020 # Society for Experimental Mechanics 2020
Abstract Background Myxomatous mitral valve degeneration is a common cause of mitral regurgitation and is often associated with mitral valve prolapse. With no known targets to pharmacologically treat mitral valve prolapse, surgery is often the only treatment option. Recently, radiofrequency ablation has been proposed as a percutaneous alternative to surgical resection for the reduction of mitral valve leaflet area. Objective Using an in vitro model of porcine mitral valve anterior leaflet enlargement following enzymatic digestion, we sought to investigate mechanisms by which radiofrequency ablation alters the geometry, microstructural organization, and mechanical properties of healthy and digested leaflets. Methods Paired measurements before and after radiofrequency ablation revealed the impact of ablation on leaflet properties. Multiphoton imaging was used to characterize changes in the structure and organization of the valvular extracellular matrix; planar biaxial mechanical testing and constitutive modeling were used to estimate mechanical properties of healthy and digested leaflets. Results Enzymatic digestion increased leaflet area and thickness to a similar extent as clinical mitral valve disease. Radiofrequency ablation altered extracellular matrix alignment and reduced the area of digested leaflets to that of control. Additionally, enzymatic digestion resulted in fiber alignment and reorientation toward the radial direction, causing increased forces during ablation and a structural stiffening which was improved by radiofrequency ablation. Conclusions Radiofrequency ablation induces radial extracellular matrix alignment and effectively reduces the area of enlarged mitral valve leaflets. Hence, this technique may be a therapeutic approach for myxomatous mitral valve disease and is thus an avenue for future study. Keywords Mitral . Valve . Prolapse . Radiofrequency . Ablation . Percutaneous . Therapy . Multiphoton . Microscopy . Biaxial . Mechanics
Introduction Mitral valve prolapse (MVP) is a common disorder of the mitral valve (MV) defined by superior displacement of one or more leaflets into the left atrium during systole [1]. As is often the case with MVP, leaflet coaptation is compromised and allows for retrograde blood flow into the left atrium. This clinical hallmark Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11340-020-00662-w) contains supplementary material, which is available to authorized users. * M. R. Bersi [email protected] 1
Department of Biomedical Engineering, Vanderbilt University, 2213 Garland Ave. Room 9425B MRBIV, Nashville, TN 37212, US
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