Flexible 3D printing of the mitral valve apparatus and left coronary artery for patients with complex anatomical variations in mitral valve surgery

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Injury to the left circumflex artery (LCA) occurs in an estimated 2.7% of patients undergoing mitral valve (MV) surgery. The average distance from the LCA to the MV varies substantially between patients but is on average 3.1 ± 1.3mm. In unfavorable anatomical variations, a 3D print of relevant anatomical structures could be helpful for a surgeon to be aware of the situation and determine a surgical strategy. In this case such a 3D print is made of a 66 year old patient with mitral valve regurgitation and a P2 prolapse assessed in the heart team for MVS. Purpose To create a flexible heart model using Computed tomography (CT) and Transesophageal echocardiography (TEE) scans of this patient that utilizes the synergistic information derived from both modalities and provides an improved method for surgical preparation in cases with unfavorable anatomical variations. Method CT and TEE scans of the heart and mitral valve are acquired and fused using Mutual information registration. Both modalities are used in the print as TEE is the gold standard for evaluating the MV prior to surgery while on CT the LCA can be visualized and the ventricle can be imaged with a higher spatial resolution. The combined reconstructions are hollowed and smoothed using Meshmixer and the Poisson disk sampling tool of Meshlab to make the reconstruction suitable for 3D printing, enhance visibility of the relevant anatomy and achieve the desired flexibility of the model. Results A flexible 3D model of the left side of the heart of a patient is created. The model consists of reconstructions of the left coronary artery (CT), the left side of the heart (CT), and the mitral valve (TEE). To expose the LCA, an indent in the tissue surrounding the LCA was made. At the apex of the heart and at the left lateral side a small window in the ventricle was created for visibility. A flexibility resembling the flexibility of tissue was created by hollowing a with walls of 1.2mm thickness and printing with Agilus 30 Clear (with a shore A value of 30) . Conclusion To our knowledge this is the first 3D print for the planning of mitral valve surgery in which CT and TEE scans are combined into one flexible print. The flexible 3D print with exposed coronary arteries allows for assessment of the mitral valve regurgitation deficit and determine a surgical strategy because of the flexibility of the model, and as the LCA is exposed in this model, the surgeon can adapt his surgical approach based on the location of the LCA.