Designing an Optical Device to Measure Aortic Leaflet Free Edge Length

Abstract

Background: Aortic cusp free edge length is a critical metric in performing aortic valve repairs. However, as measurements are taken in the unpressurized aortic valve, accurately assessing the true length of the free edge is technically challenging. Current techniques for measuring the free edge length are time-consuming, prone to inaccuracies, and often yield inconsistent results across multiple measurements. This thesis aimed to design a device capable of measuring the free edge length of aortic leaflets intraoperatively with high accuracy and reproducibility. Methods: Two approaches were considered for measuring the free edge: a direct approach involving a physical sizer inserted into the aortic root and an indirect optical approach utilizing image analysis. Stakeholder discussions favored the optical approach, leading to the development and testing of four optical measurement systems. Two methods for optical measurements were assessed (stereovision and 2D image calibration) in conjunction with two cameras (the Intel RealSense D405 and the Vitom 3D exoscope). Results: The most effective measurement system involved image analysis via 2D image calibration using the Vitom 3D exoscope. Measurements obtained through this technique exhibited a percent error rate below 10%. Measurements using the Intel RealSense D405 and stereovision were deemed ineffective due to poor camera quality and poor disparity map creation, respectively. Conclusions: 2D image calibration using photographs acquired by the Vitom 3D exoscope is a promising optical approach to measure aortic valve free edge length reproducibly and accurately.