Department of Mechanical and Materials Engineering, University of Denver, Denver, Colo.
Houston Methodist DeBakey Heart and Vascular Center, The Houston Methodist Hospital, Houston, Tex.
J Thorac Cardiovasc Surg. 2017 Jun;153(6):1303-1315.e1. doi: 10.1016/j.jtcvs.2016.12.057. Epub 2017 Feb 10.
Transcatheter heart valve implantation in failed aortic bioprostheses (valve-in-valve [ViV]) is an increasingly used therapeutic option for high-risk patients. However, high postprocedural gradients are a significant limitation of aortic ViV. Our objective was to evaluate Medtronic CoreValve Evolut R ViV hemodynamics in relation to the degree of device oversizing and depth of implantation.
Evolut R devices of 23 and 26 mm were implanted within 21-, 23-, and 25-mm Hancock II bioprostheses. Small and gradual changes in implantation depth were attempted. Hemodynamic testing was performed in a pulse duplicator under ISO-5840 standard.
A total of 47 bench-testing experiments were performed. The mean gradient of the 26-mm Evolut R in 23- and 25-mm Hancock II was lower than 23-mm Evolut R (P < .001). However, the mean gradient of 26-mm Evolut R in 21-mm Hancock II bioprostheses R (ranging from 21.30 ± 0.23 to 24.30 ± 0.22 mm Hg) was worse than 23-mm Evolut R (ranging from 15.94 ± 0.18 to 20.35 ± 0.16 mm Hg, P < .001). Furthermore, our results suggest that supra-annular implantation of 23-mm and 26-mm Evolut R devices within the bioprostheses can lead to lower gradient and improved leaflet coaptation. Regardless of implantation depth, superior transvalvular gradient is expected with 26-mm Evolut R than 23-mm Evolut R in a nonstenotic Hancock II with a true internal diameter > 17.5 mm.
The current comprehensive bench-testing assessment demonstrates the importance of both transcatheter heart valve size and device position for the attainment of optimal hemodynamics during ViV procedures. Additional in vitro testing may be required to develop hemodynamics-based guidelines for device sizing in ViV procedures in degenerated surgical bioprostheses.
经导管心脏瓣膜植入术（经导管瓣中瓣术）在高危患者中是一种越来越常用的治疗选择。然而，术后高梯度是主动脉经导管瓣中瓣术的一个显著局限性。我们的目的是评估美敦力 CoreValve Evolut R 经导管瓣中瓣术的血流动力学与器械过度扩张程度和植入深度的关系。
将 23 毫米和 26 毫米的 Evolut R 器械植入 21 毫米、23 毫米和 25 毫米 Hancock II 生物瓣中。尝试进行小而逐渐的植入深度变化。在 ISO-5840 标准下，在脉动复制器中进行血流动力学测试。
共进行了 47 次台架测试实验。26 毫米 Evolut R 在 23 毫米和 25 毫米 Hancock II 中的平均梯度低于 23 毫米 Evolut R（P<.001）。然而，21 毫米 Hancock II 生物瓣中 26 毫米 Evolut R 的平均梯度（范围为 21.30±0.23 至 24.30±0.22 毫米汞柱）比 23 毫米 Evolut R（范围为 15.94±0.18 至 20.35±0.16 毫米汞柱，P<.001）更差。此外，我们的结果表明，在生物瓣内超瓣环植入 23 毫米和 26 毫米 Evolut R 器械可导致较低的梯度和改善的瓣叶对合。无论植入深度如何，在真内径>17.5 毫米的非狭窄 Hancock II 中，26 毫米 Evolut R 预计比 23 毫米 Evolut R 具有更好的跨瓣梯度。
目前的综合台架测试评估表明，经导管心脏瓣膜大小和器械位置对于经导管瓣中瓣术获得最佳血流动力学都很重要。在退行性外科生物瓣中，可能需要额外的体外测试来制定经导管瓣中瓣术的器械尺寸基于血流动力学的指南。
