Intraoperative Hypotension is not Correlated to Perioperative Silent Brain Ischemia After Carotid Endarterectomy

Abstract

Introduction: Periprocedural ischemic brain lesions on diffusion weighted imaging (DWI) after carotid revascularization have increasingly been used as a surrogate marker for cerebral ischemia and are related to a higher chance of recurrent cerebrovascular events. It is hypothesized that patients undergoing carotid endarterectomy with intraoperative hypotension are at risk for development of new silent ischemic lesions as a result of cerebral hypoperfusion. Therefore, the current study aimed to investigate the relation between intraoperative blood pressure (BP) and the presence of silent ischemic lesions on postoperative MR-DWI in patients undergoing carotid endarterectomy. Methods: A retrospective analysis was performed based on prospectively collected data of symptomatic carotid endarterectomy patients within Utrecht Athero-Express (AE) biobank that were also included in the MRI-substudy of the international carotid stenting study (ICSS). Intraoperative hypotension was defined both as a decrease of ≥20% below baseline intraoperative BP and an absolute drop in systolic blood pressure below 80mmHg. Intraoperative hypertension is defined as an increase of ≥20% compared to baseline values. Variation in blood pressure was expressed by it's standard deviation. Intraoperative BP was measured invasively by radial artery cannula. Intraoperative BP was analyzed from time of anesthesia induction until emergence. The occurrence of intraoperative hypo- and hypertension and the duration of these changes in blood pressure were associated to the presence of ischemic lesions on MR-DWI. Results: A number of 55 symptomatic carotid stenosis patients were included in the study of which 71% male patients, with mean age (68.5 ± 9.4) and a median stenosis grade of 70-90%. A total of eight patients had new DWI-lesions (DWI positive) on postoperative MRI (5 ipsilateral and 3 both ipsi- and contralateral). Median lesion volume was 0.37mL (IQR: 0.076-7.81). Baseline characteristics between DWI-negative and DWI-positive patients did not differ. There was no difference in the median duration of intraoperative BP dropping below 80% of baseline in DWI-negative (41 minutes; IQR: 23-82) compared to DWI-positive patients (43 minutes; IQR: 25-81, p=.935). No difference was found in median duration of absolute hypotension (0 minutes; IQR 0-2 vs. 0 minutes; IQR 0-0, p=.224), and intraoperative hypertension (1 minute; IQR 0-2 vs. 1 minute; IQR 0-4, p=.417). The standard deviation of systolic intraoperative BP measurements was also comparable between the groups (24.5; IQR 21.5-28.8 vs 25.7; IQR 22.7-33.6, p=.459). Conclusion: An intraoperative period of relative hypotension compared to baseline occurred frequently. The duration of intraoperative hypotension does not seem to be related to development of perioperative DWI-lesions. Disclosure: Nothing to disclose