Reduction of Thromboembolic Potential in Cardiac Devices Via Passive Flow Control

描述（由申请人提供）：血流剪切引起的血液损伤可能导致血栓栓塞并发症，严重限制了各种心血管硬件（包括人工瓣膜、旁路泵和辅助器械）的性能。减轻心血管硬件中的高剪切应力的不利影响的有吸引力的方式是使用微型的、表面集成的被动流动控制元件（例如，涡流发生器、肋、凹坑等）其已经在机械和航空航天应用中被开发。该R21提案的重点是探索相对简单、可集成的被动流量控制元件的有效性，以实现心血管系统内血流的显著控制，目的是通过控制相干大规模剪切诱导涡流的演变来最大限度地减少血液损伤和流量损失，以增加高雷诺应力的消散，或抑制和减少流动分离。我们建议在一个理想化的双叶机械瓣膜试验台上证明这种方法的可行性，在该试验台上，将使用微型涡流发生器实施被动流量控制，以减轻小叶之间脉动流的瞬时剪切应力，从而显着减少剪切引起的血液损伤。我们在这方面的初步工作已经证明了在稳定流模型中湍流应力的减少和血液凝固的减少。在这项研究中，我们将建立在这些初步研究结果的基础上，通过优化各种被动流量控制配置（包括顺应性突起）的理想化的阀门试验台，并验证优化配置的有效性，在体外脉动血液回路。我们预计，这项研究将为以后提交的R01提案提供基础，该提案旨在进行基础研究、建模和控制血小板活化/血液损伤/血栓形成，以管理心血管硬件中的血流，从而为实现心血管硬件的新设计范例铺平道路，集成被动流量元件。公共卫生相关性：血流剪切引起的血液损伤导致人工心脏瓣膜血栓栓塞并发症。我们研究了一种新技术，以减少血流中的剪切浓度，从而使新一代心血管设备的发展。

DESCRIPTION (provided by applicant): Blood damage caused by flow shear can cause thromboembolic complications that seriously limit the performance of a broad range of cardiovascular hardware including prosthetic valves, bypass pumps, and assist device. An attractive way to mitigate the adverse effects of high shear stress in cardiovascular hardware is to use miniature, surface-integrated passive flow control elements (e.g., vortex generators, riblets, dimples, etc.) which have already been exploited in mechanical and aerospace applications. The focus of this R21 proposal is to explore the effectiveness of relatively simple, integrable passive flow control elements to achieve significant control of blood flow within cardiovascular systems with the objective of minimizing blood damage and flow losses by controlling the evolution of coherent large-scale shear-inducing eddies in order to increase dissipation of high Reynolds stresses, or suppression and reduction of flow separation. We propose to demonstrated the feasibility of this approach in an idealized bileaflet mechanical valve test-bed where passive flow control will be implemented using miniature vortex generators in order to alleviate the instantaneous shear stresses of the pulsatile flow in between the leaflets and thereby significantly reduce shear-induced blood damage. Our preliminary work in this effort has already demonstrated reduction in turbulent stresses and diminution of blood coagulation in a steady flow model. In this study, we will build on these preliminary findings by optimizing various passive flow control configurations (including conformable protrusions) on an idealized valve test-bed and validate the effectiveness of the optimized configurations in an in vitro pulsatile blood loop. We anticipate that this research will provide the basis for a later submission of an R01 proposal aimed at a fundamental investigation, modeling, and controlling platelet activation/blood damage/thrombus formation for managing blood flow in cardiovascular hardware thus paving the way towards the realization of new design paradigm for cardiovascular hardware in which blood flow losses and damage are mitigated and controlled by novel, integrated passive flow elements. PUBLIC HEALTH RELEVANCE: Blood damage caused by flow shear causes thromboembolic complications in prosthetic heart valves. We investigate a new technology to reduce shear concentrations in blood flows and thus enable the development of a new generation of cardiovascular devices.