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Abstract

Minimally invasive mitral valve surgery, transcatheter edge-to-edge repair, and thoracic endovascular aortic repair are highly complex procedures to treat mitral valve insufficiency and type B aortic dissection, respectively. Years of training are required to master these techniques and to maintain their performance at high level. However, modalities for training and interventional planning are limited as in-vivo training on animals is cost-intensive and of ethical concern, and existing in-vitro tools lack an in-vivo-like environment.

Within the scope of this thesis, novel hemodynamic simulators were developed and evaluated for their ability to model mitral valve insufficiency and type B aortic dissection. In addition, the simulators were assessed as tools for training and planning the corresponding treatment procedures.

A mitral valve simulator is presented, in which different, potentially patient-specific mitral valves can be installed. The simulator enables evaluation of the valve pathology and its subsequent treatment using either minimally invasive mitral valve surgery or transcatheter edge-to-edge repair under transesophageal echocardiography guidance. Importantly, the obtained outcomes following the interventions can each be assessed qualitatively and quantitatively, thereby allowing physicians to gain experience, plan interventions at a patient-specific level, and potentially support the treatment decision. Due to the realistic environment provided by the simulator, it may also serve as a research tool to examine and refine therapeutic procedures.

For initial research purposes, the developed mitral valve simulator was employed to investigate the accuracy of the flow convergence method. Regurgitation volumes generated by different mitral valve models were measured using the flow convergence method and particle image velocimetry. Mitral valve models encompassed different orifice shapes, including a pointed oval, drop, and circle of three different sizes. A comparison of the two techniques revealed that the flow convergence method underestimated the regurgitation volume, particularly for large orifices. Complex orifice shapes such as the pointed oval and drop led to larger inter-observer variabilities than circular orifices. While the shape affected inter-observer variability, it did not influence the underestimation of regurgitation volumes. Besides highlighting the limitations of the flow convergence method, this study demonstrates the utility of the mitral valve simulator as a research modality in the field of mitral regurgitation.

Similar to the mitral valve simulator, a flow-loop is presented, which allows for training, planning, and research of thoracic endovascular aortic repair to treat type B aortic dissection. The flow-loop was developed to incorporate entire potentially patient-specific aortic phantoms. It allows for evaluation of the phantom by computed tomography angiography, as well as the performance of thoracic endovascular aortic repair under digital subtraction angiography guidance. Moreover, flow and pressure can be assessed to evaluate potential consequences on aortic branches following the repair. The presented flow-loop enables vascular surgeons to gain experience, plan interventions, and to potentially investigate type B aortic dissections and their treatments.

Collectively, the proposed mitral valve simulator is the first to provide a realistic hemodynamic environment in-vitro that allows for the performance of both minimally invasive mitral valve surgery and transcatheter edge-to-edge repair within a single device. Similarly, the developed aortic simulator pioneers the integration of an entire patient-specific aorta in a hemodynamic flow-loop that enables the performance of thoracic endovascular repair while maintaining compatibility with clinically relevant medical imaging modalities. In conclusion, these distinctive features position the novel simulators as valuable tools for research as well as comprehensive training and patient-specific planning of interventions.