Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement
Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement
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DOI：
10.1098/rsif.2015.0737
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发表时间：
2015-12-06
影响因子：
3.9
通讯作者：
McNamara, Laoise M.
中科院分区：
文献类型：
--
作者：
Gunning, Paul S.;Saikrishnan, Neelakantan;McNamara, Laoise M.
经导管主动脉瓣置换术（TAVR）是外科主动脉瓣置换术的经皮替代方法，用于治疗主动脉瓣狭窄患者。这种微创手术依赖于TAVR支架的扩张，以使钙化的主动脉瓣叶径向移位抵靠主动脉根壁。然而，这些钙沉积物可能阻碍器械扩张，导致瓣膜支架和心包组织瓣叶变形。本研究旨在阐明偏心TAVR支架变形对体外假体组织瓣叶动态变形的影响。使用双摄像机立体摄影测量法测量在标称圆形和偏心（偏心指数= 28%）瓣口展开的TAVR瓣叶中应变的区域变化，代表体内展开的TAVR。据观察，（i）偏心支架变形导致瓣叶在峰值孔径处接合不正确，导致环形瓣膜中不存在的“剥离”瓣叶几何形状，（ii）瓣叶在峰值孔径处出现的不利弯曲，导致正常血压和高血压条件下的接合处应变显著高于环形瓣膜（正常血压：偏心性= 13.76 +/- 2.04% vs圆形= 11.77 +/-1.61%，p = 0.0014，高血压：偏心性= 15.07 +/- 1.13% vs圆形= 13.56 +/-0.87%，p = 0.0042）。本研究表明，TAVR支架的偏心变形可能对动态瓣叶变形产生相当大的影响，导致瓣叶有害弯曲并增加连合处应变，与环形展开瓣膜中的瓣叶相比，这可能加速瓣叶结构失效。
Transcatheter aortic valve replacements (TAVRs) are a percutaneous alternative to surgical aortic valve replacements and are used to treat patients with aortic valve stenosis. This minimally invasive procedure relies on expansion of the TAVR stent to radially displace calcified aortic valve leaflets against the aortic root wall. However, these calcium deposits can impede the expansion of the device causing distortion of the valve stent and pericardial tissue leaflets. The objective of this study was to elucidate the impact of eccentric TAVR stent distortion on the dynamic deformation of the tissue leaflets of the prosthesis in vitro. Dual-camera stereophotogrammetry was used to measure the regional variation in strain in a leaflet of a TAVR deployed in nominal circular and eccentric (eccentricity index = 28%) orifices, representative of deployed TAVRs in vivo. It was observed that (i) eccentric stent distortion caused incorrect coaptation of the leaflets at peak diastole resulting in a 'peel-back' leaflet geometry that was not present in the circular valve and (ii) adverse bending of the leaflet, arising in the eccentric valve at peak diastole, caused significantly higher commissure strains compared with the circular valve in both normotensive and hypertensive pressure conditions (normotension: eccentric = 13.76 +/- 2.04% versus circular = 11.77 +/- 1.61%, p = 0.0014, hypertension: eccentric = 15.07 +/- 1.13% versus circular = 13.56 +/- 0.87%, p = 0.0042). This study reveals that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.