OBJECTIVE: The authors sought to investigate noncalcific and calcific mechanisms of TAV degeneration and evaluate their impact on leaflet function by bench testing, imaging, and histology.
METHODS: TAV explants were obtained from the EXPLANT THV registry and clinical institutions. Hydrodynamic assessment was performed using a heart valve pulse duplicator system under physiological conditions. Micro-computed tomography, high-resolution photography, high speed video, and hematoxylin and eosin staining were used to evaluate the morphological appearance, leaflet kinematics, and calcium burden of TAVs.
RESULTS: A total of 14 explants were evaluated: 10 self-expanding CoreValve/Evolut TAVs (Medtronic), 3 balloon-expandable SAPIEN 3 TAVs (Edwards Lifesciences), and 1 mechanically expandable Lotus TAV (Boston Scientific). The median patient age at explantation was 73.0 years (Q1-Q3: 64.5-80.0 years), with a time to explantation of 4 years 1 month (1 year 5 months to 4 years 11 months). Six TAV explants were found to have leaflet calcification (162.4 mm3; 58.8-603.0 mm3), and 8 had no calcification detectable by micro-computed tomography and histology. All samples had impaired leaflet kinematics. There was no significant difference in the hydrodynamic mean gradient between calcified (47.2 mm Hg; 26.6-74.1 mm Hg) and noncalcified (27.6 mm Hg; 15.2-36.7 mm Hg; P = 0.28) TAVs. Leaflet calcification had a weak but nonsignificant association with the hydrodynamic mean gradient (r = 0.42; P = 0.14).
CONCLUSIONS: TAV function can be severely impacted by noncalcific and calcific mechanisms of tissue degeneration. Importantly, functional stenosis can occur in TAVs in the absence of obvious and significant calcification.
目的:作者试图研究TAV变性的非钙化和钙化机制,并通过台架试验评估其对小叶功能的影响,成像,和组织学。
方法:TAV外植体从EXPLANTTHV注册中心和临床机构获得。在生理条件下使用心脏瓣膜脉冲复制器系统进行流体动力学评估。微型计算机断层扫描,高分辨率摄影,高速视频,苏木精和伊红染色用于评估形态学外观,小叶运动学,和TAV的钙负担。
结果:总共评估了14个外植体:10个自膨胀CoreValve/EvolutTAV(Medtronic),3个气球可扩展的SAPIEN3TAV(爱德华兹生命科学),和1可机械扩展的莲花TAV(波士顿科学)。植入时的中位患者年龄为73.0岁(Q1-Q3:64.5-80.0岁),与时间4年1个月(1年5个月至4年11个月)的外植体。发现六个TAV外植体具有小叶钙化(162.4mm3;58.8-603.0mm3),8例未通过显微计算机断层扫描和组织学检测到钙化。所有样本的小叶运动学均受损。钙化(47.2mmHg;26.6-74.1mmHg)和非钙化(27.6mmHg;15.2-36.7mmHg;P=0.28)TAV之间的流体动力学平均梯度无显着差异。小叶钙化与流体动力学平均梯度的相关性较弱,但不显着(r=0.42;P=0.14)。
结论:组织变性的非钙化和钙化机制可严重影响TAV功能。重要的是,在没有明显和显著钙化的情况下,TAVs可发生功能性狭窄。