G.J. de Borst

The Value of Near-Infrared Spectroscopy Measured Cerebral Oximetry During Carotid Endarterectomy in Perioperative Stroke Prevention. A Review

BACKGROUND Transcranial Doppler (TCD) for identification of patients at risk for cerebral hyperperfusion syndrome (CHS) following carotid endarterectomy (CEA) cannot be performed in 10-15% of patients because of the absence of a temporal bone window. Near-infrared spectroscopy (NIRS) may be of additional value in these patients. We aimed to (1) compare the value of NIRS related to existing cerebral monitoring techniques in prediction of perioperative cerebral ischaemia and (2) compare the relation between NIRS and the occurrence of CHS. METHODS A systematic literature search relating to NIRS and CEA was conducted in PubMed and EMBASE databases. Those included were: (1) prospective studies; (2) on NIRS for brain monitoring during CEA; (3) including comparison of NIRS to any other intra-operative cerebral monitoring systems; and (4) on either symptomatic or asymptomatic patients. RESULTS We identified 16 studies, of which 14 focussed on the prediction of intra-operative cerebral ischaemia and shunt indication. Only two studies discussed the ability of NIRS in predicting CHS. NIRS values correlated well with TCD and electroencephalography (EEG) values indicating ischaemia. However, a threshold for postoperative cerebral ischaemia could not be determined. Neither could a threshold for selective shunting be determined since shunting criteria varied considerably across studies. The evidence suggesting that NIRS is useful in predicting CHS is modest. CONCLUSION NIRS seems a promising monitoring technique in patients undergoing CEA. Yet the evidence to define clear cut-off points for the presence of perioperative cerebral ischaemia or identification of patients at high risk of CHS is limited. A large prospective cohort study addressing these issues is urgently needed.

Editor's Choice – Management of Descending Thoracic Aorta Diseases : Clinical Practice Guidelines of the European Society for Vascular Surgery (ESVS)

Editors Choice - Management of Descending Thoracic Aorta Diseases : Clinical Practice Guidelines of the European Society for Vascular Surgery (ESVS).

Mechanism of Procedural Stroke Following Carotid Endarterectomy or Carotid Artery Stenting Within the International Carotid Stenting Study (ICSS) Randomised Trial

Objective To decrease the procedural risk of carotid revascularisation it is crucial to understand the mechanisms of procedural stroke. This study analysed the features of procedural strokes associated with carotid artery stenting (CAS) and carotid endarterectomy (CEA) within the International Carotid Stenting Study (ICSS) to identify the underlying pathophysiological mechanism. Materials and methods Patients with recently symptomatic carotid stenosis (1,713) were randomly allocated to CAS or CEA. Procedural strokes were classified by type (ischaemic or haemorrhagic), time of onset (intraprocedural or after the procedure), side (ipsilateral or contralateral), severity (disabling or non-disabling), and patency of the treated artery. Only patients in whom the allocated treatment was initiated were included. The most likely pathophysiological mechanism was determined using the following classification system: (1) carotid-embolic, (2) haemodynamic, (3) thrombosis or occlusion of the revascularised carotid artery, (4) hyperperfusion, (5) cardio-embolic, (6) multiple, and (7) undetermined. Results Procedural stroke occurred within 30 days of revascularisation in 85 patients (CAS 58 out of 791 and CEA 27 out of 819). Strokes were predominately ischaemic (77; 56 CAS and 21 CEA), after the procedure (57; 37 CAS and 20 CEA), ipsilateral to the treated artery (77; 52 CAS and 25 CEA), and non-disabling (47; 36 CAS and 11 CEA). Mechanisms of stroke were carotid-embolic (14; 10 CAS and 4 CEA), haemodynamic (20; 15 CAS and 5 CEA), thrombosis or occlusion of the carotid artery (15; 11 CAS and 4 CEA), hyperperfusion (9; 3 CAS and 6 CEA), cardio-embolic (5; 2 CAS and 3 CEA) and multiple causes (3; 3 CAS). In 19 patients (14 CAS and 5 CEA) the cause of stroke remained undetermined. Conclusion Although the mechanism of procedural stroke in both CAS and CEA is diverse, haemodynamic disturbance is an important mechanism. Careful attention to blood pressure control could lower the incidence of procedural stroke.

Platelet‐reactivity tests identify patients at risk of secondary cardiovascular events: a systematic review and meta‐analysis

Antiplatelet therapy is the standard treatment for the prevention of cardiovascular events (CVEs). High on‐treatment platelet reactivity (HPR) is a risk factor for secondary CVEs in patients prescribed aspirin and/or clopidogrel. The present review and meta‐analysis was aimed at assessing the ability of individual platelet‐function tests to reliably identify patients at risk of developing secondary CVEs.

Near-infrared spectroscopy can predict the onset of cerebral hyperperfusion syndrome after carotid endarterectomy.

Background: Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) is a potential life-threatening complication. Therefore, early identification and treatment of patients at risk is essential. CHS can be predicted by a doubling of postoperative transcranial Doppler (TCD)-derived mean middle cerebral artery blood velocity (Vmean) compared to preoperative values. However, in approximately 15% of CEA patients, an adequate TCD signal cannot be obtained due to an insufficient temporal bone window. Moreover, the use of TCD requires specifically skilled personnel. An alternative and promising technique of noninvasive cerebral monitoring is relative frontal lobe oxygenation (rSO2) measured by near-infrared spectroscopy (NIRS), which offers on-line information about cerebral oxygenation without the need for specialized personnel. In this study, we assess whether NIRS and perioperative TCD are related to the onset CHS following CEA. Methods: Patients who underwent CEA under general anesthesia and had a sufficient TCD window were prospectively included. The Vmean and rSO2 measured before induction of anesthesia were compared to measurements performed in the first postoperative hour (ΔVmean, ΔrSO2, respectively). Logistic regression analysis was performed to determine the relationship between ΔV and ΔrSO2 and the occurrence of CHS. Subsequently, receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff values. Diagnostic values were shown as positive and negative predictive values (PPV and NPV). Results: In total, 151 patients were included, of which 7 patients developed CHS. The ΔVmean and ΔrSO2 differed between CHS and non-CHS patients (median, interquartile range), i.e. 74% (67–103) versus 16% (–2 to 41), p = 0.001, and 7% (4–15) versus 1% (–6 to 7), p = 0.009, respectively. The mean arterial blood pressure did not change. Postoperative ΔVmean and ΔrSO2 were significantly related to the occurrence of CHS [odds ratio (OR) 1.40 (95% CI 1.02–1.93) per 30% increase in Vmean and OR 1.82 (95% CI 1.11–2.99) per 5% increase in rSO2]. ROC curve analysis showed an area under the curve of 0.88 (p = 0.001) for ΔVmean and an optimal cutoff value of 67% increase (PPV 38% and NPV 99%), and an area under the curve of 0.79 (p = 0.009) for ΔrSO2 and an optimal cutoff value of 3% rSO2 increase (PPV 11% and NPV 100%). The combination of both monitoring techniques provided a PPV of 58% and an NPV of 99%. Conclusions: Both TCD and NIRS measurements can be used to safely identify patients not at risk of developing CHS. It appears that NIRS is a good alternative when a TCD signal cannot be obtained.

Current Status of Clinical Magnetic Resonance Imaging for Plaque Characterisation in Patients with Carotid Artery Stenosis

OBJECTIVE The article aims to provide an overview of the literature that assessed the agreement between magnetic resonance imaging (MRI) and histology for specific carotid plaque characteristics associated with vulnerability in terms of sensitivity and specificity. METHODS A systematic search strategy was conducted in MEDLINE and EMBASE databases resulting in 1084 articles. Finally, we included 17 papers. Due to variation in presentation, especially in MRI and histology methods, a pooled analysis could not be performed. RESULTS Two studies were performed on a 3.0-T MRI scanner; all other studies were performed on a 1.5-T scanner. Most performed sequences were two-dimensional (2D) and three-dimensional (3D) T1-weighted and all histology protocols varied slightly. Our results indicate that calcification, fibrous cap, intraplaque haemorrhage and lipid-rich necrotic cores can be identified with moderate-to-good sensitivity and specificity. CONCLUSIONS Based on current literature, it appears premature for routine application of MRI as an imaging modality to assess carotid plaque characteristics associated with plaque vulnerability. Although MRI still holds promise, clinical application for plaque characterisation would require consensus regarding MRI settings and confirmation by histology. Predefined protocols for histology and MR imaging need to be established.

Clinical Relevance of Cranial Nerve Injury following Carotid Endarterectomy

OBJECTIVES The benefit of carotid endarterectomy (CEA) may be diminished by cranial nerve injury (CNI). Using a quality improvement registry, we aimed to identify the nerves affected, duration of symptoms (transient vs. persistent), and clinical predictors of CNI. METHODS We identified all patients undergoing CEA in the Vascular Study Group of New England (VSGNE) between 2003 and 2011. Surgeon-observed CNI rate was determined at discharge (postoperative CNI) and at follow-up to determine persistent CNI (CNIs that persisted at routine follow-up visit). Hierarchical multivariable model controlling for surgeon and hospital was used to assess independent predictors for postoperative CNI. RESULTS A total of 6,878 patients (33.8% symptomatic) were included for analyses. CNI rate at discharge was 5.6% (n = 382). Sixty patients (0.7%) had more than one nerve affected. The hypoglossal nerve was most frequently involved (n = 185, 2.7%), followed by the facial (n = 128, 1.9%), the vagus (n = 49, 0.7%), and the glossopharyngeal (n = 33, 0.5%) nerve. The vast majority of these CNIs were transient; only 47 patients (0.7%) had a persistent CNI at their follow-up visit (median 10.0 months, range 0.3-15.6 months). Patients with perioperative stroke (0.9%, n = 64) had significantly higher risk of CNI (n = 15, CNI risk 23.4%, p < .01). Predictors for CNI were urgent procedures (OR 1.6, 95% CI 1.2-2.1, p < .01), immediate re-exploration after closure under the same anesthetic (OR 2.0, 95% CI 1.3-3.0, p < .01), and return to the operating room for a neurologic event or bleeding (OR 2.3, 95% CI 1.4-3.8, p < .01), but not redo CEA (OR 1.0, 95% CI 0.5-1.9, p = .90) or prior cervical radiation (OR 0.9, 95% CI 0.3-2.5, p = .80). CONCLUSIONS As patients are currently selected in the VSGNE, persistent CNI after CEA is rare. While conditions of urgency and (sub)acute reintervention carried increased risk for postoperative CNI, a history of prior ipsilateral CEA or cervical radiation was not associated with increased CNI rate.

Carotid stenting versus carotid endarterectomy: evidence basis and cost implications.

OBJECTIVE Carotid Angioplasty combined with Stenting (CAS) is increasingly performed because of its presumed benefits. A study was performed to identify key factors that determine the cost-effectiveness as compared to conventional carotid endarterectomy (CEA). METHODS The incremental cost-effectiveness of CAS over CEA for different scenarios was estimated using a modeling approach. Treatment costs were based on actual costs of successful procedures whereas costs of complications were taken from the literature. Patient survival was modeled using the endarterectomy patients from the ECST trial. RESULTS Procedural costs of CAS are higher than those of CEA, mainly as a result of the high material costs. Cost-effectiveness of CAS primarily depends on major stroke rates. One percent increase in the peri-operative major stroke rate causes a cost increase of 1051 euros and a loss of 0.06 quality adjusted life years. CONCLUSIONS At present CAS is at best non-inferior to CEA in terms of clinical outcome. Cost savings due to shorter admission are offset by the high costs associated with catheter-based interventions. At present CAS should be restricted to controlled settings until clinical trials have shown a substantial clinical benefit.

Bone Marrow derived Cell Therapy in Critical Limb Ischemia: A Meta-analysis of Randomized Placebo Controlled Trials

OBJECTIVE/BACKGROUND Critical limb ischemia (CLI) is the most advanced stage of peripheral artery disease (PAD), and many patients with CLI are not eligible for conventional revascularization. In the last decade, cell based therapies have been explored as an alternative treatment option for CLI. A meta-analysis was conducted of randomized placebo controlled trials investigating bone marrow (BM) derived cell therapy in patients with CLI. METHODS The MEDLINE, Embase, and the Cochrane Controlled Trials Register databases were systematically searched, and all included studies were critically appraised by two independent reviewers. The meta-analysis was performed using a random effects model. RESULTS Ten studies, totaling 499 patients, were included in this meta-analysis. No significant differences were observed in major amputation rates (relative risk [RR] 0.91; 95% confidence interval [CI] 0.65-1.27), survival (RR 1.00; 95% CI 0.95-1.06), and amputation free survival (RR 1.03; 95% CI 0.86-1.23) between the cell treated and placebo treated patients. The ankle brachial index (mean difference 0.11; 95% CI 0.07-0.16), transcutaneous oxygen measurements (mean difference 11.88; 95% CI 2.73-21.02), and pain score (mean difference -0.72; 95% CI -1.37 to -0.07) were significantly better in the treatment group than in the placebo group. CONCLUSIONS This meta-analysis of placebo controlled trials showed no advantage of stem cell therapy on the primary outcome measures of amputation, survival, and amputation free survival in patients with CLI. The potential benefit of more sophisticated cell based strategies should be explored in future randomized placebo controlled trials.

Prediction of Cerebral Hyperperfusion after Carotid Endarterectomy with Transcranial Doppler

OBJECTIVES To determine the diagnostic value for predicting cerebral hyperperfusion syndrome (CHS) by adding a transcranial Doppler (TCD) measurement in the early postoperative phase after carotid endarterectomy (CEA). DESIGN Patients who underwent carotid endarterectomy between January 2004 and August 2010 and in whom both intra- and postoperative TCD monitoring were performed were included. METHODS In 184 CEA patients the mean velocity (V(mean)) preoperatively (V1), pre-clamping (V2), post-declamping (V3) and postoperatively (V4) was measured using TCD. The intra-operative V(mean) increase ((V3 - V2)/V2) was compared to the postoperative increase ((V4 - V1)/V1) in relation to CHS. CHS was diagnosed if the patient developed neurological complaints in the presence of a preoperative V(mean) increase >100%. RESULTS Sixteen patients (9%) had an intra-operative V(mean) increase >100% and 22 patients (12%) a postoperative V(mean) increase of >100%. In 10 patients (5%) CHS was diagnosed; two of those had an intra-operative V(mean) increase of >100% and nine postoperative V(mean) increase >100%. This results in a positive predictive value of 13% for the intra-operative and 41% for the postoperative measurement. CONCLUSIONS Besides the commonly used intra-operative TCD monitoring additional TCD measurement in the early postoperative phase is useful to more accurately predict CHS after CEA.