Alakhtar Ali, Emmott Alexander, Hart Cornelius, Mongrain Rosaire, Leask Richard L, Lachapelle Kevin
Department of Cardiac Surgery, McGill University, Montreal, Québec, Canada.
Dpartment of Surgery, Unaizah College of Medicine and Health Sciences, Qassim University, Qassim, Saudi Arabia.
BMJ Simul Technol Enhanc Learn. 2021 Jun 21;7(6):536-542. doi: 10.1136/bmjstel-2021-000868. eCollection 2021.
Three-dimensional (3D) printed multimaterial ascending aortic simulators were created to evaluate the ability of polyjet technology to replicate the distensibility of human aortic tissue when perfused at physiological pressures.
Simulators were developed by computer-aided design and 3D printed with a Connex3 Objet500 printer. Two geometries were compared (straight tube and idealised aortic aneurysm) with two different material variants (TangoPlus pure elastic and TangoPlus with VeroWhite embedded fibres). Under physiological pressure, β Stiffness Index was calculated comparing stiffness between our simulators and human ascending aortas. The simulators' material properties were verified by tensile testing to measure the stiffness and energy loss of the printed geometries and composition.
The simulators' geometry had no effect on measured β Stiffness Index (p>0.05); however, β Stiffness Index increased significantly in both geometries with the addition of embedded fibres (p<0.001). The simulators with rigid embedded fibres were significantly stiffer than average patient values (41.8±17.0, p<0.001); however, exhibited values that overlapped with the top quartile range of human tissue data suggesting embedding fibres can help replicate pathological human aortic tissue. Biaxial tensile testing showed that fiber-embedded models had significantly higher stiffness and energy loss as compared with models with only elastic material for both tubular and aneurysmal geometries (stiffness: p<0.001; energy loss: p<0.001). The geometry of the aortic simulator did not statistically affect the tensile tested stiffness or energy loss (stiffness: p=0.221; energy loss: p=0.713).
We developed dynamic ultrasound-compatible aortic simulators capable of reproducing distensibility of real aortas under physiological pressures. Using 3D printed composites, we are able to tune the stiffness of our simulators which allows us to better represent the stiffness variation seen in human tissue. These models are a step towards achieving better simulator fidelity and have the potential to be effective tools for surgical training.
创建了三维（3D）打印的多材料升主动脉模拟器，以评估聚喷射技术在生理压力下灌注时复制人体主动脉组织可扩张性的能力。
通过计算机辅助设计开发模拟器，并用Connex3 Objet500打印机进行3D打印。比较了两种几何形状（直管和理想化主动脉瘤）以及两种不同的材料变体（TangoPlus纯弹性材料和嵌入VeroWhite纤维的TangoPlus材料）。在生理压力下，计算β刚度指数，比较我们的模拟器与人体升主动脉之间的刚度。通过拉伸试验验证模拟器的材料特性，以测量打印几何形状和成分的刚度和能量损失。
模拟器的几何形状对测量的β刚度指数没有影响（p>0.05）；然而，添加嵌入纤维后，两种几何形状的β刚度指数均显著增加（p<0.001）。带有刚性嵌入纤维的模拟器明显比患者平均值更硬（41.8±17.0，p<0.001）；然而，其显示的值与人体组织数据的上四分位数范围重叠，表明嵌入纤维有助于复制病理性人体主动脉组织。双轴拉伸试验表明，与仅含弹性材料的模型相比，对于管状和动脉瘤几何形状，纤维嵌入模型的刚度和能量损失均显著更高（刚度：p<0.001；能量损失：p<0.001）。主动脉模拟器的几何形状对拉伸试验测得的刚度或能量损失没有统计学影响（刚度：p=0.221；能量损失：p=0.713）。
我们开发了与动态超声兼容的主动脉模拟器，能够在生理压力下再现真实主动脉的可扩张性。使用3D打印复合材料，我们能够调节模拟器的刚度，从而更好地反映人体组织中观察到的刚度变化。这些模型朝着实现更好的模拟器逼真度迈出了一步，并且有可能成为有效的手术训练工具。
