Computational fluid dynamics simulations of left atrial appendage occlusion based on patient-specific 3D-printed models

Atrial fibrillation (AF) is one of the most common cardiac arrythmias, with a 20% prevalence in patients aged 80 years or older. AF has been identified as the main cause of thromboembolic events and is associated with a five-fold increase in the risk of stroke. Moreover, in more than 90% of cases, intracardial thrombus originated in the left atrial appendage (LAA) due to its morphology and the compromising effects of AF that compromises the atrial function increasing the stroke risk. The standard treatment to prevent stroke involves oral anticoagulation therapy. However, this treatment has several contraindications which might outweigh its benefits. These considerations, added to the involvement of the LAA as the primary site of thrombus formation, define the rationale for the development of non-pharmacological approaches. A viable alternative is the mechanical LAA occlusion via endocardial devices. In this scenario, computational fluid dynamic (CFD) simulations could improve intervention by evaluating, in advance, the types of occluders and their positioning. However, to date, only a limited number of in-silico studies explicitly incorporate LAAO devices in fluid simulations. The purpose of this thesis is to assess the fluid dynamic effects of LAAO in AF patients to predict hemodynamic changes due to the occlusion. To this aim, three 3D-printed LA models, derived from computed tomography (CT) scans, were used to simulate different implants of two commercially available occlusion devices (plug- and pacifier-type). CFD simulations of the tested setups have been performed, and various parameters were calculated to quantify the risk of stroke pre- and post-occlusion. This approach allowed the quantification of the benefits of proper device positioning in a controlled experimental setting. Moreover, the use of two different devices enabled the assessment of the impact of closure surface conformation on atrial fluid dynamics and related parameters.