Georgia Institute of Technology, Atlanta, Georgia.
Emory University Hospitals, Atlanta, Georgia.
JACC Cardiovasc Interv. 2015 Dec 28;8(15):2026-2033. doi: 10.1016/j.jcin.2015.08.028. Epub 2015 Nov 27.
The aim of this study was to investigate the hemodynamic performance of a transcatheter heart valve (THV) deployed at different valve-in-valve positions in an in vitro model using a small surgical bioprosthesis.
Patients at high surgical risk with failing 19-mm surgical aortic bioprostheses are not candidates for valve-in-valve transcatheter aortic valve replacement, because of risk for high transvalvular pressure gradients (TVPGs) and patient-prosthesis mismatch.
A 19-mm stented aortic bioprosthesis was mounted into the aortic chamber of a pulse duplicator, and a 23-mm low-profile balloon-expandable THV was deployed (valve-in-valve) in 4 positions: normal (bottom of the THV stent aligned with the bottom of the surgical bioprosthesis sewing ring) and 3, 6, and 8 mm above the normal position. Under controlled hemodynamic status, the effect of these THV positions on valve performance (mean TVPG, geometric orifice area, and effective orifice area), thrombotic potential (sinus shear stress), and migration risk (pullout force and embolization flow rate) were assessed.
Compared with normal implantation, a progressive reduction of mean TVPG was observed with each supra-annular THV position (normal: 33.10 mm Hg; 3 mm: 24.69 mm Hg; 6 mm: 19.16 mm Hg; and 8 mm: 12.98 mm Hg; p < 0.001). Simultaneously, we observed increases in geometric orifice area (normal: 0.83 cm(2); 8 mm: 1.60 cm(2); p < 0.001) and effective orifice area (normal: 0.80 cm(2); 8 mm: 1.28 cm(2); p < 0.001) and reductions in sinus shear stresses (normal: 153 dyne/cm(2); 8 mm: 40 dyne/cm(2); p < 0.001), pullout forces (normal: 1.55 N; 8 mm: 0.68 N; p < 0.05), and embolization flow rates (normal: 32.91 l/min; 8 mm: 26.06 l/min; p < 0.01).
Supra-annular implantation of a THV in a small surgical bioprosthesis reduces mean TVPG but may increase the risk for leaflet thrombosis and valve migration. A 3- to 6-mm supra-annular deployment could be an optimal position in these cases.
本研究旨在通过体外模型使用小尺寸外科生物瓣研究经导管心脏瓣膜（THV）在不同瓣中瓣位置的血流动力学性能。
对于 19 毫米外科主动脉生物瓣出现功能障碍且外科手术风险较高的患者，由于跨瓣压力梯度（TVPG）较高且存在患者-瓣膜不匹配，不适合行经导管主动脉瓣置换瓣中瓣（valve-in-valve）技术。
将 19 毫米带支架的主动脉生物瓣安装在脉动流复制器的主动脉腔内，并在 4 个位置（THV 支架的底部与外科生物瓣缝合环的底部对齐）部署一个 23 毫米的低剖面球囊扩张型 THV（瓣中瓣）：正常位置和在正常位置上方 3、6 和 8 毫米处。在控制血流动力学状态下，评估这些 THV 位置对瓣膜性能（平均 TVPG、有效瓣口面积和有效瓣口面积）、血栓形成潜力（窦剪切力）和迁移风险（拔出力和栓塞流速）的影响。
与正常植入相比，每个瓣上 THV 位置均观察到平均 TVPG 逐渐降低（正常：33.10 mmHg；3 毫米：24.69 mmHg；6 毫米：19.16 mmHg；8 毫米：12.98 mmHg；p <0.001）。同时，我们观察到瓣口面积（正常：0.83 cm2；8 毫米：1.60 cm2；p <0.001）和有效瓣口面积（正常：0.80 cm2；8 毫米：1.28 cm2；p <0.001）增加，窦剪切力（正常：153 达因/cm2；8 毫米：40 达因/cm2；p <0.001）、拔出力（正常：1.55 N；8 毫米：0.68 N；p <0.05）和栓塞流速（正常：32.91 l/min；8 毫米：26.06 l/min；p <0.01）降低。
在小尺寸外科生物瓣瓣中瓣植入 THV 可降低平均 TVPG，但可能增加瓣叶血栓形成和瓣膜迁移的风险。在这种情况下，3 至 6 毫米瓣上植入可能是最佳位置。
