Safety of perioperative cerebral oxygen saturation during debranching in patients with incomplete circle of Willis

Abstract

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 (rSO 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 >100 mm 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.