Endangered cerebral blood supply after closure of left subclavian artery: Postmortem and clinical imaging studies

Background. The aim of this study was to assess hemodynamic consequences of increasingly common coverage of the left subclavian artery (LSA) during endovascular stent-graft repair for thoracic aortic disease without surgical revascularization. We considered that critical arteries to examine are the right vertebral artery and posterior communicating arteries (PComA) because their simultaneous insufficiency would drastically endanger posterior cerebral circulation. The existence and the diameters of these arteries were studied in a postmortem anatomic study with review of clinical craniocervical computed tomographic (CT) and magnetic resonance (MR) angiographies. Methods. The anatomic material was collected as a part of forensic medicine autopsies. The anatomy of the cerebral arteries of 92 deceased was assessed by angiography and permanent silicone casts. Results. In five individuals (5.4%) the risk for acute neurological complication after "unprotected" closure of the LSA was estimated to be "substantial" because the diameter of the right vertebral artery above the posterior inferior cerebellar artery was less than 2 mm and was associated with incomplete PComA and in three additional cases (3.3%) with only hypoplastic right vertebral artery, as "possible." Review of a clinical teaching file of MR and CT angiographies with anatomic variations and abnormalities of the circle of Willis identified, also, other variants with increased risk. Conclusions. When the LSA is closed, insufficient posterior cerebral circulation due to anatomic reasons occurs relatively infrequently, but in order to avoid the debilitating complications in these cases, careful imaging of the right vertebral artery up to the basilar artery is mandatory, and if proven hypoplastic, imaging of PComAs is necessary.