Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif.
Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Mechanical Engineering, Stanford University, Stanford, Calif.
J Thorac Cardiovasc Surg. 2019 Aug;158(2):392-403. doi: 10.1016/j.jtcvs.2018.10.145. Epub 2018 Nov 15.
The optimal conduit for valve-sparing aortic root replacement is still debated, with several conduit variations available, ranging from straight tubular grafts to Valsalva grafts. Benefits of neosinus reconstruction include enhanced flow profiles and improved hemodynamics. Curiously, however, some clinical data suggest that straight grafts may have greater long-term durability. In this study, we hypothesized that straight tubular grafts may help maintain the native cylindrical position of the aortic valve commissures radially, resulting in preserved leaflet coaptation, reduced stresses, and potentially improved valve performance.
Using 3D printing, a left heart simulator with a valve-sparing root replacement model and a physiologic coronary circulation was constructed. Aortic valves were dissected from fresh porcine hearts and reimplanted into either straight tubular grafts (n = 6) or Valsalva grafts (n = 6). Conduits were mounted into the heart simulator and hemodynamic, echocardiographic, and high-speed videometric data were collected.
Hemodynamic parameters and coronary blood flow were similar between straight and Valsalva grafts, although the former were associated with lower regurgitant fractions, less peak intercommissural radial separation, preserved leaflet coaptation, decreased leaflet velocities, and lower relative leaflet forces compared with Valsalva grafts.
Valsalva grafts and straight grafts perform equally well in terms of gross hemodyanics and coronary blood flow. Interestingly, however, the biomechanics of these 2 conduits differ considerably, with straight grafts providing increased radial commissural stability and leaflet coaptation. Further investigation into how these parameters influence clinical outcomes is warranted.
用于主动脉瓣保留型主动脉根部替换的理想移植物仍存在争议，目前有多种移植物类型可供选择，包括直管型移植物和瓦尔萨尔瓦（Valsalva）移植物。窦管重建的益处包括改善血流形态和血流动力学。然而，一些临床数据表明，直管型移植物可能具有更好的长期耐久性。本研究假设直管型移植物可帮助维持主动脉瓣交界的天然圆柱状位置，从而实现瓣叶对合的维持、张力降低，并可能改善瓣膜功能。
使用 3D 打印技术构建了一个具有主动脉瓣保留型根部替换模型和生理性冠状动脉循环的左心模拟系统。从新鲜猪心解剖主动脉瓣并重新植入直管型移植物（n=6）或瓦尔萨尔瓦移植物（n=6）。将移植物安装到心脏模拟系统中，并收集血流动力学、超声心动图和高速摄像测量数据。
直管型和瓦尔萨尔瓦移植物的血流动力学参数和冠状动脉血流量相似，但前者反流分数较低，跨交界径向分离峰值较低，瓣叶对合维持较好，瓣叶速度较低，相对瓣叶力较低。
瓦尔萨尔瓦移植物和直管型移植物在总体血流动力学和冠状动脉血流量方面表现相当。然而，有趣的是，这两种移植物的生物力学特性存在显著差异，直管型移植物提供了更高的跨交界径向稳定性和瓣叶对合。进一步研究这些参数如何影响临床结果是必要的。
