Design and direct metal laser sintering of replacement heart valves

退行性心脏瓣膜疾病是欧洲和北美老龄化人口日益严重的问题。此外，在南亚和非洲等低收入和中等收入国家，数以千万计的年轻人和老年人因细菌感染而经历瓣膜衰竭。目前心脏瓣膜疾病的治疗技术正迅速向经导管方法发展，寻求部署由激光切割金属管的框架组成的替代瓣膜。然而，为了开发新的阀门概念，更好地应对全球现有和新出现的挑战，可能需要替代的制造方法。为了抓住这个机会，我们成功地进行了一项初步的试点研究，涉及使用直接金属激光烧结（DMLS）的增材制造阀门框架。在这样做的过程中，我们已经证明了3D打印这些类型的薄支柱结构的可行性。现在，有必要从根本上优化和评估替代心脏瓣膜框架的DMLS制造工艺。两个合作站点将使用世界领先的DMLS设施。在南安普顿大学的工程设计制造中心和意大利工业合作伙伴Sisma中，一台概念激光机器已经运行了三年多，Sisma实际上制造了自己的高精度DMLS机器，这些机器将由公司内部的专家使用。因此，Sisma将在增材制造方面提供必要的专业知识，这对于心脏瓣膜框架的小而薄的特征将是无价的。此外，该项目将显著受益于南安普顿大学的Mu-Vis成像中心，该中心对框架的高分辨率扫描将有助于确定制造精度、准确性和质量。一旦制造过程得到优化，它将被用于制造和测试两个新的框架概念，这两个概念都是通过3D打印的增材特性实现的。其中一个框架将基于径向分层框架的专利知识产权，在部署过程中不会产生长度变化。第二个框架将采用大学硕士项目中设计的概念，该项目于2018年9月结束。第二个概念旨在克服需要更换先前部署的已开始失效的假体瓣膜的问题。当假体小叶以与天然瓣膜相似的方式退化时，就会发生这种情况。目前，标准的替换阀门被用于一种称为“阀中阀”的过程，这种过程不涉及专门为这种重做过程设计的设备。除了这些工程任务外，我们还非常关注我们的影响途径，特别是在发达国家和中低收入国家心脏瓣膜患者的不同需求方面。在项目结束时，我们将(i)详细了解金属烧结阀框架的最大精度、精度和结构完整性的最佳设置，（ii）开发两个通过增材制造实现的新设备概念，其中一个将专门用于治疗世界各地的年轻患者。

Degenerative heart valve disease is a growing problem in the ageing populations of Europe and North America. Further, tens of millions of both young and old people experience valve failure from bacterial infections in low- and middle-income countries such as those in South Asia and Africa.The current state of the art for the treatment of heart valve disease is rapidly moving towards transcatheter approaches, seeking to deploy replacement valves comprising frames that are laser cut from metallic tubes. However, to develop new valve concepts that can better address existing and emerging challenges globally, alternative manufacturing methods will likely be necessary. In response to this opportunity, we successfully conducted a preliminary pilot study involving additive manufacturing of valve frames using direct metal laser sintering (DMLS). In so doing, we have demonstrated the feasibility of 3D printing these type of thin strut structures.Now, it is necessary to fundamentally optimise and assess the DMLS manufacturing process for replacement heart valve frames. World-leading facilities will be used for DMLS at both partner sites. A Concept Laser machine has been operated for over three years in the Engineering Design Manufacturing Centre at the University of Southampton and the Italian industry partner, Sisma, which actually manufactures its own high precision DMLS machines which will be used by specialists within the company. Consequently, Sisma will provide the necessary expertise in additive manufacturing, something that will be invaluable for the small, thin features of heart valve frames. Also, the project will significantly benefit from the Mu-Vis Imaging Centre at the University of Southampton in which high resolution scans of the frames will help to determine manufacturing precision, accuracy and quality.Once the manufacturing process has been optimised, it will be used to manufacture and test two new frame concepts, both made possible by the additive nature of 3D printing. One of the frames will be based on patented intellectual property for a radially layered frame that produces zero change of length during deployment. The second frame will feature a concept that was devised in a Masters project at the University that came to an end in September 2018. This second concept aims to overcome the problems associated with the need to replace a previously deployed prosthetic valve that has started to fail. This can happen when prosthetic leaflets degenerate in similar ways to native valves. Currently, standard replacement valves are used in a procedure know as valve-in-valve which doesn't involve a device specifically designed for such redo procedures.In addition to these engineering tasks, we have a strong focus on our pathway to impact, particularly in relation to the contrasting needs of heart valve patients in both developed and low- and middle-income countries. At the end of the project, we will have (i) a detailed understanding of optimal settings for maximum precision, accuracy and structural integrity of metal sintered valve frames and (ii) developed two novel device concepts made possible by additive manufacturing one of which will be specifically designed for treating young patients across all territories of the world.