An efficient computational approach to guide intervention in treatment of stroke

Ischaemic stroke (IS) occurs when a cerebral vessel becomes obstructed by a blood clot. One of the most effective treatment options consists of capturing the clot with a catheter-guided stent, while reducing haemodynamic forces on the clot through aspiration and a balloon to halt or reverse flow and reduce risk of clot fragmentation. This often relies on the individual skills of the clinicians performing the operation, and it is difficult to predict how treatment options such as balloon location or aspiration rates might influence clinical outcome. The aim of this thesis is to test and develop a computational tool to examine what-if scenarios prior to IS treatment and identify the scenario most likely to deliver favourable haemodynamic conditions such as flow reversal. Building upon an existing 1D arterial blood  flow model (openBF), this was further developed to simulate a typical clinical case of IS and its treatment outcomes following intervention with a balloon guided catheter for a variety of typical anatomies, vascular properties and treatment options. Results show that retrograde flow in the L-MCA (incident area) is not possible to induce with aspiration rates up to 5 ml/s, however the retrieval and treatment path demonstrate flow reversal (L-ICAs and L-ACA distal). The simulations performed provided understanding of flow directions and their magnitudes throughout the thrombectomy procedure which satisfied the aim of developing a computational tool that can assess flow alterations caused by the treatment. Results also demonstrate the importance of certain vessels during treatment and in networks that have missing vessels as they allow collateral flow and assist in maintaining steady distribution of flow to the brain when there is an occlusion. Missing vessel configurations presented reduced flows in the L-MCA, never retrograde. Configurations that had missing parts of the distal CoW (ACoA and proximal ACAs) presented significantly low flows in the L-ACA distal and L-MCA, and forward flow in the distal L-ICA which was retrograde with its proximal counterpart in all other variations during aspiration. Ageing vascular properties demonstrated unfavourable increase to flow in the L-MCA post-retrieval during aspiration. Increased viscosity presented small reductions in flow globally. To further complement the study, an analytical assessment of the catheter importance was carried out. Results showed that certain catheters in typical vessels present significantly large pressure drops and velocities in comparison to no catheter.