Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen, University, Aachen, Germany.
Med. Klinik und Poliklinik II, Universitätsklinikum Bonn, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
J Biomech. 2014 Mar 21;47(5):957-65. doi: 10.1016/j.jbiomech.2014.01.024. Epub 2014 Jan 21.
Although CT-studies as well as intraoperative analyses have described broad anatomic variations of the aortic annulus, which is predominantly found non-circular, commercially available transcatheter aortic heart valve prostheses are circular. In this study, we hypothesize that the in vitro hydrodynamic function of a self-expanding transcatheter heart valve (Medtronic CoreValve) assessed in an oval compartment representing the aortic annulus will differ from the conventionally used circular compartment.
Medtronic CoreValve prostheses were tested in specifically designed and fabricated silicone compartments with three degrees of defined ovalities. The measurements were performed in a left heart simulator at three different flow rates. In this setting, regurgitation flow, effective orifice area, and systolic pressure gradient across the valve were determined. In addition, high speed video recordings were taken to investigate leaflet kinematics.
The pressure difference across the prosthesis increased with rising ovality. The effective orifice areas were only slightly impacted. The analyses of the regurgitation showed minor changes and partially lower regurgitation when switching from round to slightly oval settings, followed by strong increases for further ovalization. The high speed videos show minor central leakage and impaired leaflet apposition for strong ovalities, but no leaflet/stentframe contact in any setting.
This study quantifies the influence of oval expansion of transcatheter heart valve prostheses on their hydrodynamic performance. While slight ovalities were well tolerated by a self-expanding prosthesis, more significant ovality led to worsening of prosthesis function and regurgitation.
尽管 CT 研究以及术中分析已经描述了主动脉瓣环的广泛解剖学变异，其主要是非圆形的，但市售的经导管主动脉心脏瓣膜假体是圆形的。在这项研究中，我们假设在代表主动脉瓣环的椭圆形腔室中评估自膨式经导管心脏瓣膜（美敦力 CoreValve）的体外流体动力学功能将不同于传统上使用的圆形腔室。
美敦力 CoreValve 假体在专门设计和制造的硅酮腔室中进行测试，该腔室具有三种不同程度的规定椭圆形。在左心模拟器中以三种不同的流速进行测量。在此设置下，确定反流流量、有效瓣口面积和跨瓣收缩压梯度。此外，还进行了高速视频记录以研究瓣叶运动学。
随着椭圆形的增加，假体两端的压差增加。有效瓣口面积仅受到轻微影响。反流分析显示，从圆形切换到略微椭圆形设置时，反流变化较小且部分降低，然后进一步椭圆形化时反流急剧增加。高速视频显示轻微的中心泄漏和瓣叶对合不良，对于强烈的椭圆形，但是在任何设置中都没有瓣叶/支架框架接触。
这项研究定量了经导管心脏瓣膜假体椭圆形扩张对其流体动力学性能的影响。虽然轻微的椭圆形变形可以被自膨式假体很好地耐受，但更显著的椭圆形变形会导致假体功能和反流恶化。
