Safety Of Perioperative Cerebral Oxygen Saturation During Debranching In Patients With Incomplete Circle Of Willis

OBJECTIVES: The consequences of common carotid artery (CCA) cross-clamping during debranching before thoracic endovascular aortic repair are unclear. We examined the safety of a simple CCA cross-clamping procedure under regional cerebral oxygen saturation monitoring (rS0(2)) in patients with a complete or incomplete circle of Willis (CoW) anatomy.METHODS: Twenty-eight patients with thoracic aneurysm underwent elective debranching thoracic endovascular aortic repair with bilateral frontal rSO(2) monitoring at our institution between January 2012 and October 2015. Before CCA cross-clamping, we maintained a systemic mean arterial pressure of >100mm Hg with a vasopressor. We recorded the bilateral frontal rSO(2) before, during and after CCA cross-clamping.RESULTS: The CoW was incomplete in 11 (39.3%) patients. Of these, 6 patients had a complication of ischaemic potential. The left frontal rSO(2) was <50% in 3 patients but did not fall below 40%. Compared with baseline values (mean +/- SD 64.6 +/- 6.9%), the left frontal rSO(2) showed no significant change perioperatively in those with a complete CoW on the left CCA cross-clamping (during: 61.0 +/- 7.9%, P= 0.17; after: 65.1 +/- 5.9%, P= 0.09). In patients with an incomplete CoW with ischaemic potential, the left frontal rSO(2) did not change significantly after cross-clamping (baseline: 59.8 +/- 3.2%, during: 55.5 +/- 5.0%; P = 0.10) but increased significantly on declamping (62.8 +/- 4.5%, P = 0.023). The extent of the changes in the mean left frontal rSO(2) on clamping and declamping decreased and increased by 7.3% and 11.7%, respectively, in patients with an incomplete CoW, when compared with 5.3% and 5.8% in those with a complete CoW (P = 0.65 and 0.31, respectively). No perioperative cerebrovascular events were observed.CONCLUSIONS: Simple CCA cross-clamping during debranching was safe when arterial pressure was supported and rSO(2) was monitored, even with an incomplete CoW and ischaemic potential.