Development of a computational aspiration thrombectomy model: Application of a two-phase flow approach to describe thrombus behavior

Abstract

Acute Ischemic Stroke (AIS) is an abrupt onset of a focal neurological deficit due to the occlusion of a cerebral artery caused by thrombosis or embolism. According to the World Health Organization, stroke is the second leading cause of death in the world. One of the available treatments is the aspiration thrombectomy, where a negative pressure is applied to the thrombus in order to remove it from the vessel. In this work, the aspiration thrombectomy will be studied through the development of a computational model. By means of the development of this model, a baseline is created for exploratory research into both the technical and clinical aspects. The range of applied thrombus models in literature varies largely. In this work, the thrombus is modelled using a fluid material model. Through the application of this fluid model, an emphasis is put on the fluid properties of thrombi, which exhibit both solid and fluid behavior. Three fluid models are applied, of which two represent non-Newtonian fluid behavior and one Newtonian fluid behavior. The effects of these material models are assessed through the pressure and velocity distribution and the thrombus behavior. Furthermore, an evaluation of three clinical parameters, aspiration pressure, suction distance and thrombus length, is performed. Each parameter was assigned three variations, which are assessed based on the respective recanalization times. Each clinical parameter is evaluated to influence the recanalization time, albeit to different extents. In conclusion, this thesis functions as exploratory research in the development of computational aspiration thrombectomy models. Future research is advised, in the form of material model verification with patient-retrieved or analog clots or more extensive research into the relation between recanalization time and the presented clinical parameters.