The role of haemodynamic analysis in high flow extracranial to intracranial bypass surgery

"Use of computational haemodynamics technology is well described for a number of diverse conditions in medicine including predicting flows in the Circle of Willis, risk of rupture of aneurysms, and optimum endovascular stent placement in the management of vascular pathology. Saphenous vein or radial artery interposition grafts are often used for high-flow extracranial-intracranial bypass procedures. These bypasses have the potential to supply a considerable volume of cerebral blood flow to the brain. However, long-term patency for specific graft types remains unknown. This is a computation haemodynamic analysis of consecutive interposition bypass cases. The bypasses are between the common carotid artery (CCA) and intracranial Internal carotid artery (ICA) or middle cerebral artery (MCA). Emerging evidence supports a pathogenic role of abnormal wall shear stress (WSS) and pressure turbulence flow as important factors in the development of early graft failure at the anastomotic site. This study aimed to develop a computational fluid dynamics simulator for assessing flow in cerebral high flow revascularisation bypass grafts and to study the impact of variations in the anastomosis angle and pressure gradient across bypass. Also the optimum mean arterial pressure required for maintaining the graft flow was investigated.