Enhancing the Force Validated Heart Valve Surgical Planning Tool - ABSTRACT While advances in cardiac surgery have revolutionized the treatment of heart valve disease, problems remain with the durability of surgical repair techniques, devices and replacement valves. A major challenge in perfecting the design of these procedures and devices is to ensure that post-operatively the valve functions under the lowest possible stress to ensure its longevity. This is particularly true for the mitral valve, which faces the highest pressures and forces of the four cardiac valves. The force is equal to two regular bottles of water in gravity, 100,000 timers per day. The seriousness of the problem is dire; according to recent American Heart Association reports, recurrence of moderate to severe insufficiency at 12 months following surgical repair of ischemic mitral valve regurgitation is still more than 30%. While information for surgical planning or device design can be based on computer simulations built from available medical imaging modalities with assumed or measured material properties of the heart and valve tissue, these material properties are often associated with significant simplifications and thus the simulation may not accurately reflect the true forces and strains on the cardiac valves. The goal of this work is to build upon the success of the first phase of the project, and demonstrate use of a new, force-validated model of the human mitral valve for patient-specific surgical planning and intelligent device development, using nature’s own stress-minimization concepts. We hypothesize that constructing computational models using experimental force and shape measurements obtained from both healthy porcine and human valves will result in a more precise system for surgical planning, device development, and FDA device approval. The porcine mitral valve has for more than three decades been accepted as a highly relevant anatomic basis of the human mitral valve. Within this project, we will obtain images from both human and porcine hearts to obtain the geometry of major valve landmark points, then explant the heart from the animal / donor, and mount the dissected mitral valves in a valve-specific dedicated holder that is 3D printed to match each animal and human’s individual anatomy. The mitral valve will then undergo high resolution 3D imaging while allowing the valve to remain open and closed under physiological conditions. Detailed force measurements will be performed on the same valves to ensure that correct biomechanical boundary conditions are obtained. These high-resolution data will then inform a computational model of the valve that will be tested and validated against the clinical measurements obtained in vivo prior to heart explantation. At the conclusion of this project we will employ the model in one exemplary mitral valve repair surgery to demonstrate the significant advantage of force validated computational models and show the hypothesized self-supporting capabilities of the valve. The project participants’ competencies are interdisciplinary and highly relevant to the project. Expertise is brought together from cardiovascular experimentation, clinical work, and computational modeling.
