Image-based numerical modeling of blood dynamics in presence of regurgitant and repaired mitral valve

Understanding the complete functionality of the heart plays a fundamental role in the prevention of cardiovascular diseases, which are the main causes of death in the world. One of these diseases is mitral valve regurgitation, a pathological condition leading to an incomplete closure of the mitral valve during the systolic phase. Examples of possible consequences are atrial fibrillation and pulmonary oedema. The main cause of mitral regurgitation is mitral valve prolapse that is an excessive displacement of the mitral leaflets towards the left atrium, which can lead the leaflets to no longer guarantee a complete closure of the valve in systole. To treat mitral valve prolapse, there are two surgical techniques: the Resection technique and the Neochordae technique. Despite their effectiveness, there is still debate in the literature as to which one is the most optimal to re-establish a ventricular fluid dynamic that is as physiological as possible. The goal of this Thesis is to explore the blood flow patterns within the left heart when mitral valve regurgitation and surgical repair techniques are present. Specifically, we will employ computational fluid dynamic models where the displacement of the left heart geometries (left ventricle, left atrium and aortic root) and valves (aortic and mitral valve) are obtained from dynamic imaging. In particular, in this Thesis, we will introduce four main innovative aspects: 1. Exploring blood flow dynamics under both healthy and mitral valve regurgitation conditions. Specifically, we will reconstruct, for the first time, the left heart geometry and the motion of a patient with mitral regurgitation to examine certain occurrences, such as the formation of hemolysis and an enhanced ability to prevent thrombi formation; 2. Exploring various models for the mitral dynamics, with a specific focus on comparing the different approaches. This is due to the fact that the mitral valve, during the diastolic phase, assumes different geometric configurations (fully opened, partial closure and re-opening). The goal is to determine whether it is crucial to consider all possible mitral valve configurations during the diastolic phase; 3. Exploring and comparing the Neochordae and Resection technique. This particular subject has been explored only by performing a structural analysis (i.e. no blood flow dynamics). On the contrary, we want to explore the impact of these two repair techniques on ventricular flow. Our study will focus on the haemodynamic aspect, including the potential risk of red blood cell damage, ventricular washout, and remodeling. Moreover, for the first time, we want to reconstruct the patient-specific mitral valve geometries subjected to the repair surgical techniques; 4. Examining how the sub-valvular apparatus, consisting of chordae and papillary muscles, influences blood flow patterns in both healthy and mitral valve regurgitation scenarios.