Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305.
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305.
J Biomech Eng. 2020 Jan 1;142(1):0145011-9. doi: 10.1115/1.4044142.
Few technologies exist that can provide quantitative data on forces within the mitral valve apparatus. Marker-based strain measurements can be performed, but chordal geometry and restricted optical access are limitations. Foil-based strain sensors have been described and work well, but the sensor footprint limits the number of chordae that can be measured. We instead utilized fiber Bragg grating (FBG) sensors-optical strain gauges made of 125 μm diameter silica fibers-to overcome some limitations of previous methods of measuring chordae tendineae forces. Using FBG sensors, we created a force-sensing neochord (FSN) that mimics the natural shape and movement of native chordae. FBG sensors reflect a specific wavelength of light depending on the spatial period of gratings. When force is applied, the gratings move relative to one another, shifting the wavelength of reflected light. This shift is directly proportional to force applied. The FBG sensors were housed in a protective sheath fashioned from a 0.025 in. flat coil, and attached to the chordae using polytetrafluoroethylene suture. The function of the force-sensing neochordae was validated in a three-dimensional (3D)-printed left heart simulator, which demonstrated that FBG sensors provide highly sensitive force measurements of mitral valve chordae at a temporal resolution of 1000 Hz. As ventricular pressures increased, such as in hypertension, chordae forces also increased. Overall, FBG sensors are a viable, durable, and high-fidelity sensing technology that can be effectively used to measure mitral valve chordae forces and overcome some limitations of other such technologies.
目前几乎没有技术可以提供二尖瓣装置内的力的定量数据。可以进行基于标记的应变测量，但腱索几何形状和有限的光学访问是限制因素。已经描述了基于箔片的应变传感器，并且效果很好，但是传感器足迹限制了可以测量的腱索数量。相反，我们利用光纤布拉格光栅（FBG）传感器-由 125μm 直径的二氧化硅纤维制成的光学应变计-来克服以前测量腱索力的方法的一些局限性。使用 FBG 传感器，我们创建了一个力感新腱索（FSN），该新腱索模仿天然腱索的自然形状和运动。FBG 传感器根据光栅的空间周期反射特定波长的光。当施加力时，光栅彼此相对移动，从而改变反射光的波长。这种位移与施加的力成正比。FBG 传感器被放置在由 0.025 英寸扁平线圈制成的保护鞘中，并使用聚四氟乙烯缝线固定在腱索上。在 3D 打印的左心模拟器中验证了力感新腱索的功能，该模拟器表明 FBG 传感器可以在 1000Hz 的时间分辨率下对二尖瓣腱索提供高度灵敏的力测量。随着心室压力的增加，例如在高血压中，腱索力也会增加。总体而言，FBG 传感器是一种可行，耐用且高保真的传感技术，可有效用于测量二尖瓣腱索力，并克服其他类似技术的一些局限性。
