Subtle Cerebral Damage after Shunting vs Non Shunting during Carotid Endarterectomy

The effect of the collateral cerebrovascular circulation on tolerance to carotid artery cross-clamping and on early outcome after carotid endarterectomy

OBJECTIVE

The Circle of Willis (CoW) serves as the primary source of contralateral blood supply in patients who undergo carotid artery cross-clamping (CC) for carotid endarterectomy (CEA). It has been suggested that the CoW's anatomy influences CEA outcomes. The aim of this study was to evaluate associations between the cerebral collateral circulation, a positive awake test for intraoperative neurologic deficit after carotid CC, and postoperative adverse neurologic events.

METHODS

A systematic review was conducted searching MEDLINE, Cochrane, and Web of Science databases for studies that assessed the cerebral circulation, including CoW variations, using neuroimaging techniques in patients who underwent carotid CC. For the metanalytical incidence, the statistical technique used was weight averaging. Otherwise, descriptive analysis was used due to the excessive heterogeneity of the studies.

RESULTS

Eight publications, seven cohort and one case-controlled study, involving 1313 patients who underwent carotid artery CC under loco-regional anesthesia, were included in the systematic review. The incidence of positive awake test in the cohort studies ranged from 4.4% to 19.7%. Carotid artery CC resulted in positive awake test in 5% to 91% of patients with alterations in the anterior portion and in 27% to 74% with alterations in the posterior portion of the CoW. A positive awake test in patients with contralateral carotid stenosis or occlusion ranged from 5.8% to 45.7%. Contralateral carotid stenosis >70% or occlusion were associated with a positive awake test (P < .001). Patients with incomplete CoW did not have statistically significant correlation with intraoperative neurological deficits after CC. Data were insufficient to evaluate the effect of the collateral circulation on early outcome after CEA.

CONCLUSIONS

In this systematic review, contralateral carotid artery stenosis or occlusion, but not CoW abnormalities, were associated with a positive awake test after carotid artery CC. Further research is needed to evaluate which specific CoW anomaly predicts neurologic deficit after CC and to confirm association between a positive awake test and clinical outcome after CEA.

A systematic review & meta-analysis on perioperative cerebral and hemodynamic monitoring methods during carotid endarterectomy

OBJECTIVE

To compare outcomes between different strategies of perioperative cerebral and hemodynamic monitoring during carotid endarterectomy.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and Cochrane CENTRAL databases were searched.

METHODS

This review was performed according to the PRISMA guidelines and prospectively registered in the international prospective register of systematic reviews (CRD42021241891). The GRADE approach was used to describe the methodological quality of the studies and certainty of the evidence. The primary outcome was 30-day stroke rate. Secondary outcomes measures are 30-day ipsilateral stroke, 30-day mortality, shunt rate and complication rates.

RESULTS

The search identified 3 460 articles. Seventeen RCTs, three prospective observational studies and seven registries were included, reporting on 236 983 patients. The overall pooled 30-day stroke rate is 1.8% (95% CI 1.4 - 2.2%), ranging from 0 - 12.6%. In RCT's the pooled 30-day stroke rate is 2.7% (95% CI 1.6 - 3.7%) compared to 1.3% (95%CI 0.8 - 1.8%) in the registries. The overall stroke risk decreased from 3.7% before the year 2000 to 1.6% after 2000. No significant differences could be identified between different monitoring and shunting strategies, although a trend to higher stroke rates in routine no shunting arms of RCTs was observed. Overall 30-day mortality, myocardial infarction and nerve injury rates are 0.6% (95%CI 0.4 - 0.8), 0.8% (95%CI 0.6-1.0) and 1.3% (95%CI 0.4-2.2), respectively.

CONCLUSIONS

No significant differences between the compared shunting and monitoring strategies are found. However, routine no shunting is not recommended. The available data is too limited to prefer one method of neuromonitoring over another method when selective shunting is applied.

Outcomes and role of shunting during carotid endarterectomy for symptomatic patients

OBJECTIVE

Shunt placement during carotid endarterectomy (CEA) is often advocated to protect the ischemic penumbra in patients with symptomatic carotid stenosis. This study assesses the effect of shunt placement on postoperative stroke risk in symptomatic patients undergoing CEA.

METHODS

We queried the American College of Surgeons National Surgical Quality Improvement Program database (2016-2019) for CEA cases with complete CEA procedure-targeted data. Symptomatic patients were identified as having a preoperative diagnosis of stroke on presentation (DS), transient ischemic attack (TIA), amaurosis fugax (AF), or temporary monocular blindness (TMB). DS patients were further analyzed according to the severity of their stroke based on their modified Rankin Scale (mRS). To better assess the effect of shunt placement on stroke rate, we compared cases of CEA with patch angioplasty technique, with and without the use of intraoperative shunt. Patients who underwent carotid eversion or primary closure were excluded. Baseline demographics and perioperative outcomes were compared using Chi-square and Mann-Whitney U test. Multivariate analysis was performed to identify independent risk factors for postoperative stroke and cranial nerve injury.

RESULTS

We identified 4,652 cases of CEA with patch angioplasty in symptomatic patients, including 1,889 (40.6%) with shunt placement and 2,763 (59.4%) without. Age, race, and sex distributions were similar for both procedures. Compared to patients without shunt, those with shunt had significantly higher rates of emergency (9.1% vs 7.0%, P = .010) and non-elective surgery (40.3% vs 37.2%, P = .035), general anesthesia (97.0% vs 86.3%, P < .001), and bleeding disorders (27.2% vs 22.7%, P < .001). Thirty-day incidence of postoperative stroke was similar between patients who had shunt placement (3.2%) and those who did not (2.6%) (P = .219). Additionally, subgroup analysis failed to show any benefit of shunting on postoperative stroke regardless of preoperative symptoms or neurologic disability. In contrast, shunt placement was associated with increased rate of cranial nerve injury (4.1% vs 2.4%, P = .001). Multivariate analysis revealed that non-elective surgery (OR 1.99, 95% CI 1.36-2.91, P < .001) and DS (vs TIA/AF/TMB) (OR 1.64, 95% CI 1.12-2.41, P = .012) were predictive of 30-day postoperative stroke. After adjusting for confounders, shunt placement had no effect on stroke risk at 30 days but remained an independent risk factor for cranial nerve injury (aOR 1.87, 95% CI 1.32-2.64, P < .001).

CONCLUSIONS

In symptomatic patients undergoing CEA with patch angioplasty, shunting is associated with increased risk of cranial nerve injury without reduction in postoperative stroke risk.

Routine or selective carotid artery shunting for carotid endarterectomy (and different methods of monitoring in selective shunting)

BACKGROUND

Temporary interruption of cerebral blood flow during carotid endarterectomy can be avoided by using a shunt across the clamped section of the carotid artery. The shunt may improve the outcome. This is an update of a Cochrane review originally published in 1996 and previously updated in 2002, 2009, and 2014.

OBJECTIVES

To assess the effect of routine versus selective or no shunting, and to assess the best method for selective shunting on death, stroke, and other complications in people undergoing carotid endarterectomy under general anaesthesia.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched April 2021), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2021, Issue 4), MEDLINE (1966 to April 2021), Embase (1980 to April 2021), and the Science Citation Index Expanded (SCI-EXPANDED) (1980 to April 2021). We also searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform, and handsearched relevant journals, conference proceedings, and reference lists.

SELECTION CRITERIA

Randomised and quasi-randomised trials of routine shunting compared with no shunting or selective shunting, and trials that compared different shunting policies in people undergoing carotid endarterectomy.

DATA COLLECTION AND ANALYSIS

Three independent review authors performed data extraction, selection, and analysis. A pooled Peto odds ratio (OR) and 95% confidence interval (CI) were computed for all outcomes of interest. Best and worse case scenarios were also calculated in case of unavailable data. Two authors independently assessed risk of bias, and quality of evidence using GRADE.

MAIN RESULTS

No new trials were found for this updated review. Thus, six trials involving 1270 participants are included in this latest review: three trials involving 686 participants compared routine shunting with no shunting, one trial involving 200 participants compared routine shunting with selective shunting, one trial involving 253 participants compared selective shunting with and without near-infrared refractory spectroscopy monitoring, and the other trial involving 131 participants compared shunting with a combination of electroencephalographic and carotid pressure measurement with shunting by carotid pressure measurement alone. Only three trials comparing routine shunting and no shunting were eligible for meta-analysis. Major findings of this comparison found that the routine shunting had less risk of stroke-related death within 30 days of surgery (best case) than no shunting (Peto odds ratio (OR) 0.13, 95% confidence interval (CI) 0.02 to 0.96, I² not applicable, P = 0.05, low-quality evidence), the routine shunting group had a lower stroke rate within 24 hours of surgery (Peto odds ratio (OR) 0.15, 95% CI 0.03 to 0.78, I² = not applicable, P = 0.02, low-quality evidence), and ipsilateral stroke within 30 days of surgery (best case) (Peto OR 0.41, 95% CI 0.18 to 0.97, I² = 52%, P = 0.04, low-quality evidence) than the no shunting group. No difference was found between the groups in terms of postoperative neurological deficit between selective shunting with and without near-infrared refractory spectroscopy monitoring. However, this analysis was inadequately powered to reliably detect the effect. There was no difference between the risk of ipsilateral stroke in participants selected for shunting with the combination of electroencephalographic and carotid pressure assessment compared with pressure assessment alone, although again the data were limited.

AUTHORS' CONCLUSIONS

This review concluded that the data available were too limited to either support or refute the use of routine or selective shunting in carotid endarterectomy when performed under general anaesthesia. Large-scale randomised trials of routine shunting versus selective shunting are required. No method of monitoring in selective shunting has been shown to produce better outcomes.

Impact of intraoperative neurologic deficits in carotid endarterectomy under regional anesthesia

OBJECTIVE

Patients undergoing carotid endarterectomy (CEA) may experiment neurologic deficits during the carotid cross-clamping due to secondary cerebral hypoperfusion. An associated risk of postoperative stroke incidence is also well established. This work aimed to assess the postoperative adverse events related to neurologic deficits in the awake test after clamping and to determine its predictive factors. Methods. From January 2012 to January 2018, 79 patients from a referral hospital that underwent CEA with regional anesthesia for carotid stenosis and manifested neurologic deficits were gathered. Consecutively selected controls (n = 85) were submitted to the same procedure without developing neurological changes. Postoperative complications such as stroke, myocardial infarction, all-cause death, and Clavien-Dindo classification were assessed 30 days after the procedure. Univariate and binary logistic regressions were performed for data assessment. Results. Patients with clamping associated neurologic deficits were significantly more obese than the control group (aOR = 9.30; 95% CI: 2.57-33.69; p = .01). Lower degree of ipsilateral stenosis and higher degree of contralateral stenosis were independently related to clamping intolerance (aOR = 0.70; 95% CI: 0.49-0.99; p = .047 and aOR = 1.30; 95% CI: 1.06-1.50; p = .009, respectively). Neurologic deficits were a main 30-day stroke predictor (aOR = 4.30; 95% CI: 1.10-16.71; p = .035). Conclusions. Neurologic deficits during carotid clamping are a predictor of perioperative stroke. Body mass index > 30 kg/m², a lower degree of ipsilateral stenosis, and a higher degree of contralateral stenosis are independent predictors of neurologic deficits and, therefore, might play a role in the prevention of procedure-related stroke.

Benefit of selective shunt use during carotid endarterectomy under regional anesthesia

Objectives

Carotid cross-clamping during endarterectomy exposes the patient to intraoperative neurological deficits due to embolism or cerebral hypoperfusion. To prevent further cerebrovascular incidents, resorting to shunt is frequently recommended. However, since this method is also considered a stroke risk factor, the use is still controversial. This study aims to shed some light on the best approach regarding the use of shunt in symptomatic cerebral malperfusion after carotid artery cross-clamping.

Methods

From January 2012 to January 2018, 79 patients from a tertiary referral hospital who underwent carotid endarterectomy with regional anesthesia for carotid artery stenosis and manifested post-clamping neurologic deficits were prospectively gathered. Shunt use was left to the decision of the surgeon and performed in 31.6% (25) of the patients. Demographics, comorbidities, imaging tests, and clinical/intraoperative features were evaluated. For data assessment, univariate analysis was performed.

Results

Regarding 30-day stroke, 30-day postoperative complications (stroke, surgical hematoma, hyperperfusion syndrome), and cranial nerve injury, no significant differences were found ( P = 0.301, P = 0.460, and P = 0.301, respectively) between resource to shunt and non-shunt. Clamping and surgery times were significantly higher in the shunt group ( P < 0.001 and P = 0.0001, respectively).

Conclusions

Selective-shunting did not demonstrate superiority for patients who developed focal deficits regarding stroke or other postoperative complications. However, due to the limitations of this study, the benefit of shunting cannot be excluded. Further randomized trials are recommended for precise results on this matter with current sparse clinical evidence.

Using serum s100-β protein as a biomarker for comparing silent brain injury in carotid endarterectomy and carotid artery stenting

BACKGROUND

S100-β protein has been introduced as a sensitive biomarker of silent cerebral injury. This study compares its serum levels before, during, and 24 hours after carotid artery stenting (CAS) and carotid endarterectomy (CEA).

METHODS

We measured serum level of S100-β in arterial blood before (S100Ba), during (S100Bb), and 24 hours after (S100Bc) CAS and CEA. We assessed differences in S100-β levels using non-parametric tests. We analyzed the relationship between carotid plaque type (echolucency) and S100-β protein level. We also examined its relation to the oximetry results in the CEA group (ipsilateral and contralateral).

RESULTS

Thirty patients were enrolled, including 15 CAS and 15 CEA patients, with no significant differences in baseline atherosclerotic characteristics. There was no significant difference in S100Ba or S100Bb levels between CAS and CEA patients. However, a significant difference was found in S100Bc: 331.3 pg/mL (IQ range 56.4-583.5) for CAS vs. 76.3 pg/mL (IQ range 29.7-117.4) for CEA (P=0.01). Type I and II plaques were associated with the higher S100Bc levels in CAS (P=0.048). S100Bc was higher in CEA patients when the contralateral cerebral hemisphere had oximetry values less than 60% (P=0.043).

CONCLUSIONS

Our study suggests that CAS might produce silent brain injury. Moreover, vulnerable plaques might be associated with higher levels of S100-β protein, especially in CAS. This pilot study demonstrates that S100-β is a useful biomarker for silent brain injury in carotid revascularization. Large scale studies are still needed to confirm these findings.

Copeptin Levels Do Not Correlate With Cross-Clamping Time in Patients Undergoing Carotid Endarterectomy Under General Anesthesia

Copeptin is a sensitive and more stable surrogate marker for arginine vasopressin. In this study, we evaluated copeptin levels in carotid endarterectomy (CEA) patients, perioperatively, to determine whether copeptin levels can be related to carotid artery cross clamping (CC) time and to postoperative neurological outcomes. Copeptin, interleukin 6, C-reactive protein, cortisol, and brain natriuretic peptide were measured preoperatively (T1) and 3 hours postoperatively (T3) as well as intraoperatively (T2). We recruited 77 patients. Values of copeptin rose gradually over the observed times: T1 = 7.9 (6.4-9.6), T2 = 12.6 (9.3-16.8), and T3 = 72.3 (49.1-111.2) pmol/L. There was a significant difference for repeated measurement ( P = .000, P = .000, and P = .000). Duration of carotid artery CC during CEA does not affect postoperative copeptin level (CC ≤ 13 minutes: 106.8 ± 93.6 pmol/L, CC > 13 minutes: 96.7 ± 89.1 pmol/L; P = .634). Preoperative copeptin level was significantly higher in patients with ulcerated plaque morphology. Activation of the stress axis in patients undergoing CEA results in copeptin elevation. Duration of CC during CEA does not affect postoperative copeptin levels.

Oxidative Stress and Total Antioxidant Status During Internal Carotid Artery Clamping with or without Shunting: An Experimental Pilot Study

Background

The exact role of shunting during carotid endarterectomy remains controversial and unclear. The aim of this experimental study was to investigate to what degree carotid clamping may induce changes in the cerebral oxidative status and to focus on the relation of these changes with shunt insertion.

Material/Methods

Forty New-Zealand rabbits were randomized into 4 groups: group 1 classifying animals with carotid shunt and patent contralateral carotid artery; group 2 shunt and occlusion of the contralateral carotid artery; group 3 no-shunt and patent contralateral carotid artery; and group 4 no-shunt and occlusion of the contralateral carotid artery. Blood samples were collected from the ipsilateral internal jugular vein, immediately after carotid clamping (time 0), and then at 5, 10, 15, 30, and 60 minutes afterwards. Evaluation of oxidative stress was accomplished by measuring the lag-time, representing the initial phase of oxidation, rate of accumulation (RA), showing concentration of free oxygen radical and total antioxidant status (TAS) representing antioxidant composition of serum.

Results

Lag-time was significantly different in time points 0, 30 and 60 minutes within each different group. TAS was significantly different in time points 0, 15 and 60 min and RA in time points 0, 5, 10 and 60 min within each different group. 60 minutes after carotid clamping, the rate of accumulation as well as lag-time and TAS were increased in all groups, independently of using or not shunting or the presence of contralateral occlusion. After comparing groups 1, 2 and 3 regarding lag-time, TAS and RA, we did not find statistical difference among the groups at any time point. On the contrary, groups 1, 2 and 3 did show significantly different values comparing to group 4 after 60 min of occlusion.

Conclusions

Our experimental work based on cerebral metabolism found a significantly higher oxidative stress in models with contralateral carotid occlusion. The use of shunt in all other models did not have any influence on oxidative response. Future human studies should focus on the relation of oxidative status and shunt insertion to determine the benefit of selective or routine shunting during CEA.

Fluctuations of serum neuron specific enolase and protein S-100B concentrations in relation to the use of shunt during carotid endarterectomy

Objective

To evaluate the changes in serum neuron specific enolase and protein S-100B, after carotid endarterectomy performed using the conventional technique with routine shunting and patch closure, or eversion technique without the use of shunt.

Materials and Methods

Prospective non-randomized study included 43 patients with severe (>80%) carotid stenosis undergoing carotid endarterectomy in regional anesthesia. Patients were divided into two groups: conventional endarterectomy with routine use of shunt and Dacron patch (csCEA group) and eversion endarterectomy without the use of shunt (eCEA group). Protein S-100B and NSE concentrations were measured from peripheral blood before carotid clamping, after declamping and 24 hours after surgery.

Results

Neurologic examination and brain CT findings on the first postoperative day did not differ from preoperative controls in any patients. In csCEA group, NSE concentrations decreased after declamping (P<0.01), and 24 hours after surgery (P<0.01), while in the eCEA group NSE values slightly increased (P=ns), accounting for a significant difference between groups on the first postoperative day (P=0.006). In both groups S-100B concentrations significantly increased after declamping (P<0.05), returning to near pre-clamp values 24 hours after surgery (P=ns). Sub-group analysis revealed significant decline of serum NSE concentrations in asymptomatic patients shunted during surgery after declamping (P<0.05) and 24 hours after surgery (P<0.01), while no significant changes were noted in non-shunted patients (P=ns). Decrease of NSE serum levels was also found in symptomatic patients operated with the use of shunt on the first postoperative day (P<0.05). Significant increase in NSE serum levels was recorded in non-shunted symptomatic patients 24 hours after surgery (P<0.05).

Conclusion

Variations of NSE concentrations seemed to be influenced by cerebral perfusion alterations, while protein S-100B values were unaffected by shunting strategy. Routine shunting during surgery for symptomatic carotid stenosis may have the potential to prevent postoperative increase of serum NSE levels, a potential marker of brain injury.

Brain diffusion changes in unilateral carotid artery stenosis with non-shunt endarterectomy: Correlation with white matter lesions

OBJECTIVE

Carotid stenosis is associated with hemodynamic cerebral ischemia. Diffusion-weighted MR imaging allows for the assessment of changes related to alterations in tissue integrity. The aim of this study was to investigate (a) whether white matter lesions (WML) and apparent diffusion coefficient (ADC) values differ between ipsilateral and contralateral hemispheres, (b) whether ADC values are related to WMLs and common vascular risk factors, and (c) whether ADC values differ after carotid endarterectomy (CEA) without a shunt in patients with unilateral internal carotid artery stenosis (ICAS).

METHODS

Twenty-five patients (16 men, 9 women; mean age of 68 years) with unilateral ICAS (≥ 70% carotid stenosis) were assessed with brain MRI before and after CEA, prospectively. Two experienced radiologists scored the WMLs. Bilateral ADC values in anterior and posterior periventricular WM, occipital WM, and thalamus were evaluated on preoperative and postoperative MRI. Differences in ADC values and WML scores between the two hemispheres were assessed and associations between ADC values, WML scores, and explanatory variables (e.g., age, sex, vascular risk factors) were analyzed.

RESULTS

WMLs were significantly greater and ADC values were elevated in the ipsilateral cerebral WM. After CEA, ADC values rapidly decreased but remained higher than within the contralateral hemisphere. Ipsilateral hemispheric ADC values were associated with basal ganglia WMLs. No association between ADC values and vascular risk factors was found.

CONCLUSION

ICAS is associated with increased diffusion in normal-appearing WM in comparison to more prominent chronic ischemic lesions. CEA has a partial effect on diffusion. These cerebral changes may be related to chronic low-grade ischemic damage that is induced by ICAS.

The impact of intraoperative shunting on early neurologic outcomes after carotid endarterectomy

BACKGROUND

Although the need for intraoperative shunting during carotid endarterectomy (CEA) is intensely debated, relatively few studies have compared the neurologic outcomes of patients undergoing CEA with or without shunts. The objective of our analysis was to determine the impact of intraoperative shunting during CEA on the incidence of postoperative stroke.

METHODS

The 2012 CEA-targeted American College of Surgeons National Surgical Quality Improvement Program database was used for this analysis. The preoperative and operative characteristics of patients undergoing CEA with or without intraoperative shunting were compared. From this overall sample, propensity score techniques were then used to match patients with or without intraoperative shunting for a number of variables, including age, degree of ipsilateral and contralateral carotid stenosis, presence of several anatomic or physiologic risk factors, anesthesia modality, and use of patch angioplasty vs primary arteriotomy closure. The 30-day postoperative mortality and combined stroke/transient ischemic attack (TIA) rates of this matched cohort were then compared. A similar analysis was also performed on a subgroup of patients with severe stenosis or occlusion of the contralateral carotid artery.

RESULTS

A total of 3153 patients were included for initial analysis (2023 "no-shunt" patients vs 1130 "shunt" patients). From this overall sample, propensity score matching yielded a cohort of 1072 patients with or without intraoperative shunt placement who were well matched for all known patient- and procedure-related factors. There was no significant difference in the incidence of postoperative stroke/TIA between the two groups of this matched cohort (3.4% in the no-shunt group vs 3.7% in the shunt group; P = .64). Analysis of a similarly well matched subgroup of patients with severe stenosis or occlusion of the contralateral carotid artery demonstrated a statistically nonsignificant increase in the incidence of postoperative stroke/TIA with the use of intraoperative shunting (4.9% in the no-shunt group vs 9.8% in the shunt group; P = .08).

CONCLUSIONS

There is no clinical benefit to intraoperative shunting during CEA, even in patients who may be at high risk for intraoperative cerebral hypoperfusion due to severe stenosis or occlusion of the contralateral carotid artery.

Routine or selective carotid artery shunting for carotid endarterectomy (and different methods of monitoring in selective shunting)

BACKGROUND

Temporary interruption of cerebral blood flow during carotid endarterectomy can be avoided by using a shunt across the clamped section of the carotid artery. This may improve outcome. This is an update of a Cochrane review originally published in 1996 and previously updated in 2009.

OBJECTIVES

To assess the effect of routine versus selective or no shunting during carotid endarterectomy, and to assess the best method for selecting people for shunting.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched August 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2013, Issue 8), MEDLINE (1966 to August 2013), EMBASE (1980 to August 2013) and Index to Scientific and Technical Proceedings (1980 to August 2013). We handsearched journals and conference proceedings, checked reference lists, and contacted experts in the field.

SELECTION CRITERIA

Randomised and quasi-randomised trials of routine shunting compared with no shunting or selective shunting, and trials that compared different shunting policies in people undergoing carotid endarterectomy.

DATA COLLECTION AND ANALYSIS

Three review authors independently performed the searches and applied the inclusion criteria. For this update, we identified two new relevant randomised controlled trials.

MAIN RESULTS

We included six trials involving 1270 participants in the review: three trials involving 686 participants compared routine shunting with no shunting, one trial involving 200 participants compared routine shunting with selective shunting, one trial involving 253 participants compared selective shunting with and without near-infrared refractory spectroscopy monitoring, and the other trial involving 131 participants compared shunting with a combination of electroencephalographic and carotid pressure measurement with shunting by carotid pressure measurement alone. In general, reporting of methodology in the included studies was poor. For most studies, the blinding of outcome assessors and the report of prespecified outcomes were unclear. For routine versus no shunting, there was no significant difference in the rate of all stroke, ipsilateral stroke or death up to 30 days after surgery, although data were limited. No significant difference was found between the groups in terms of postoperative neurological deficit between selective shunting with and without near-infrared refractory spectroscopy monitoring, However, this analysis was inadequately powered to reliably detect the effect. There was no significant difference between the risk of ipsilateral stroke in participants selected for shunting with the combination of electroencephalographic and carotid pressure assessment compared with pressure assessment alone, although again the data were limited.

AUTHORS' CONCLUSIONS

This review concluded that the data available were too limited to either support or refute the use of routine or selective shunting in carotid endarterectomy. Large scale randomised trials of routine shunting versus selective shunting are required. No method of monitoring in selective shunting has been shown to produce better outcomes.

Selective shunt during carotid endarterectomy using routine awake test with respect to a lower shunt rate

PURPOSE

To evaluate shunt rate and discuss the resultsrelated to selective shunt placement during carotid endarterectomy (CEA) using routine awake test.

METHODS

Patients with CEA from 2007 to 2011 were retrospectively reviewed from prospectively collected data. The need for shunt placement was determined by the awake test, based on the alteration in the neurologic examination. We collected data by using the clinical records and imaging studies, and investigated factors related to selective shunt such as collateral circulation and contralateral internal carotid artery (ICA) stenosis.

RESULTS

There were 45 CEAs under regional anesthesia with the awake test in 44 patients. The mean age was 61.8 ± 7.1 years old. There were 82.2% (37/45) of males, and 68.9% (31/45) of symptomatic patients. Selective shunt placement had been performed in only two (4.4%) patients. Among them fewer cases (4%) had severe (stenosis >70%) contralateral ICA lesions, and more cases (91%) of complete morphology of the anterior or posterior circulation in the circle of Willis. There was no perioperative stroke, myocardial infarctionor death, and asymptomatic new brain lesions were detected in 4 patients (9%), including 2 cases of selective shunt placement.

CONCLUSION

CEA under routine awake test could besafe and feasible method with low shunt placement rate in selected patients.

Silent stroke and cognitive decline in asymptomatic carotid stenosis revascularization

The aim of this study was to assess the relationship between serum levels of S100 β and neuron-specific enolase (NSE), postoperative diffusion-weighted magnetic resonance imaging (DW-MRI) and Mini-Mental State Examination (MMSE) score in asymptomatic patients affected by ≥70% carotid stenosis submitted to carotid endarterectomy (CEA) or carotid artery stenting (CAS), and to compare MMSE scores and DW-MRI findings at follow-up evaluations. Between April 2008 and April 2009, 60 patients were submitted to carotid intervention. All patients underwent DW-MRI and MMSE preoperatively, at 24 hours postoperatively, at 6 months and at 12 months. Neurobiomarkers were assessed for each patient at six time-points. Thirty-two patients were submitted to CEA and 28 to CAS. No mortality was observed. One CAS patient presented with an ischemic stroke. In six CAS patients and one CEA patient, new subclinical ischemic lesions were detected at postoperative DW-MRI (21.4% versus 3%, P = 0.03). In CAS patients, new DW-MRI lesions were significantly associated with MMSE score decline ( P = 0.001). At 12 months, patients presenting with new postoperative ischemic lesions showed lower MMSE scores ( P = 0.08). CAS patients showed increasing neurobiomarker levels compared with CEA patients ( P = 0.02). In conclusion, microembolization effects may persist over time, so it should be avoided whenever possible. Carotid revascularization procedures should be evaluated and compared not only with respect to death/stroke but also to microembolism rates.

Impact of practice patterns in shunt use during carotid endarterectomy with contralateral carotid occlusion

PURPOSE

This study investigated the association between surgeon practice pattern in shunt placement and 30-day stroke/death in patients undergoing carotid endarterectomy (CEA) with contralateral carotid occlusion (CCO).

METHODS

Among 6379 CEAs performed in the Vascular Study Group of New England (VSGNE) between 2002 and 2009, we identified 353 patients who underwent CEA with CCO and compared the 30-day stroke/death rate with 5279 patients who underwent primary, isolated CEA with a patent contralateral carotid artery. Within patients with CCO, we examined the 30-day stroke/death rate across the reason for shunt placement and two distinct surgeon practice patterns in shunt placement: surgeons who selectively used a shunt (≤95% of CEAs) or routinely used a shunt (>95% of CEAs). We used observed/expected (O/E) ratios to provide risk-adjusted comparisons across groups.

RESULTS

Of 353 patients with CCO, 118 (33%) underwent CEA without a shunt, 173 (49%) underwent CEA using a shunt placed routinely, and 62 (18%) had a shunt placed for a neurologic indication. Rates of 30-day stroke/death across categories of reason for shunt use were no shunt, 3.4%; routine shunt, 4.0%; and shunt for indication, 4.8% (P = .891). The risk of 30-day stroke/death was higher for surgeons who selectively placed shunts (5.6%) in all their CEAs and lower for surgeons who routinely placed shunts (1.5%, P = .05). The risk of 30-day stroke/death was >1 in patients undergoing selective shunting (O/E ratio, 1.4; 95% confidence interval [CI], 1.1-1.7) and <1 for surgeons who placed shunts routinely (O/E ratio, 0.4; 95% CI, 0.2-0.9). Stroke/death rates were lowest when individual surgeons' intraoperative decisions reflected their usual pattern of practice: 1.5% stroke/death rate when "routine" surgeons placed a shunt, 3.4% when "selective" surgeons did not place a shunt, and 7.6% stroke/death rate for "selective" surgeons who placed a shunt (P = .05 for trend).

CONCLUSIONS

The risk of 30-day stroke/death is higher in CEA in patients with CCO than with a patent contralateral carotid artery. Surgeons who place shunts selectively during CEA have higher rates of stroke/death in patients with CCO. This suggests that shunt use for CCO during CEA is associated with fewer complications, but only if the surgeon uses a shunt as part of his or her routine practice in CEA. Surgeons should preoperatively consider their own practice pattern in shunt use when faced with a patient who may require shunt placement.

Shunting during carotid endarterectomy

BACKGROUND

The use of shunting during carotid endarterectomy (CEA) is controversial. While some surgeons advocate routine shunting, others prefer selective shunting or no shunting. Several large series have documented excellent results of CEA with routine shunting or without shunts. Others reported similar results with selective shunting using transcranial Doppler (TCD), electroencephalogram (EEG) monitoring, carotid stump pressure (SP), cervical block anesthesia (CBA), and somatosensory evoked potential (SSEP). In this study, we review the available evidence supporting shunting, nonshunting, and selective shunting during CEA.

METHODS

An electronic PubMed/MEDLINE search was conducted to identify all published CEA studies between January 1990 and December 2010, that analyzed the perioperative outcome of routine shunting, routine nonshunting, routine versus selective shunting, selecting shunting versus avoiding a shunt, and selective shunting based on EEG, TCD, SP, CBA, and SSEP.

RESULTS

The mean reported perioperative stroke rate for CEAs with routine shunting was 1.4% and for routine nonshunt was 2%. Meanwhile, the mean perioperative stroke rates for selecting shunting were 1.6% using EEG, 4.8% using TCD, 1.6% using SP, 1.8% using SSEP, and 1.1% for CBA. Similar results were noted for perioperative stroke and death rates.

CONCLUSIONS

The use of routine shunting and selective shunting was associated with a low stroke rate. Both methods are acceptable, and the individual surgeon should select the method with which they are more comfortable.

Routine or selective carotid artery shunting for carotid endarterectomy (and different methods of monitoring in selective shunting)

BACKGROUND

Temporary interruption of cerebral blood flow during carotid endarterectomy can be avoided by using a shunt across the clamped section of the carotid artery. This may improve outcome. This is an update of a Cochrane Review originally published in 1996 and previously updated in 2001.

OBJECTIVES

To assess the effect of routine versus selective, or never, shunting during carotid endarterectomy, and to assess the best method for selecting patients for shunting.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched September 2008), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 2009), MEDLINE (1966 to November 2008), EMBASE (1980 to November 2008) and Index to Scientific and Technical Proceedings (1980 to November 2008). We handsearched journals and conference proceedings, checked reference lists, and contacted experts in the field.

SELECTION CRITERIA

Randomised and quasi-randomised trials of routine shunting compared with no shunting or selective shunting, and trials that compared different shunting policies in patients undergoing carotid endarterectomy.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the searches and applied the inclusion criteria. We identified one new relevant randomised controlled trial.

MAIN RESULTS

We included four trials in the review: three trials involving 686 patients compared routine shunting with no shunting; the other trial involving 131 patients compared shunting with a combination of electroencephalographic and carotid pressure measurement with shunting by carotid pressure measurement alone. Allocation was adequately concealed in one trial, and one trial was quasi-randomised. Analysis was by intention-to-treat where possible. For routine versus no shunting, there was no significant difference in the rate of all stroke, ipsilateral stroke or death up to 30 days after surgery, although data were limited. There was no significant difference between the risk of ipsilateral stroke in patients selected for shunting with the combination of electroencephalographic and carotid pressure assessment compared to pressure assessment alone, although again the data were limited.

AUTHORS' CONCLUSIONS

This review concluded that the data available were too limited to either support or refute the use of routine or selective shunting in carotid endarterectomy. It was suggested that large scale randomised trials between routine shunting versus selective shunting were required. No one method of monitoring in selective shunting has been shown to produce better outcomes.