Abstract 17300: Development and Ex Vivo Validation of Novel Force-Sensing Neo-Tendons for Measuring Chordae Tendineae Tension in the Mitral Valve Apparatus Using Optical Fibers With Embedded Bragg Gratings

Abstract

Introduction: Very few technologies exist that can provide quantitative data on forces within the mitral valve apparatus. Marker based strain measurements can be performed, but chordae heterogeneity limits utility. Foil-based strain sensors have also been described, but tend to be bulky, limiting the number of chordae that can be measured. Hypothesis: We hypothesize that the use of Fiber Bragg Grating (FBG) sensors—optical strain gauges made of 125 μ m diameter silica fibers— can overcome the critical limitations of previous methods of measuring chordae tendineae forces. Methods: Using FBG sensors, we created a force-sensing neochord that would mimic the natural shape and movement of native chordae tendineae. FBG sensors reflect a specific wavelength of light depending on the spatial period of gratings - when a force is applied, the gratings move relative to one another, changing the reflected light (Fig 1A). This wavelength shift is directly proportional to the force applied. The FBG sensors were housed in a protective sheath fashioned from the outer coil of a 0.025" Amplatz Extra-Stiff guidewire, and attached to the chordae using GoreTex suture (Fig 1B). The function of the force-sensing neochordae were validated in a 3D printed left heart simulator. Results: FBG sensors provided high-fidelity force measurements of mitral valve chordae tendineae at a temporal resolution of 1000 Hz. As ventricular pressures increased, such as in the hypertensive condition, forces on the chordae also increased (Fig 1C). The resolution of FBG sensors allow for increased accuracy of not only chordae tension, but also the rate of change of force (dF/dt) - a parameter critical to determining likelihood of leaflet rupture. Conclusions: FBG sensors are a viable, durable, and high-fidelity technology that can be effectively used to measure mitral valve chordae forces and overcome limitations of other such technologies.