Carotid Artery Stenting: Current Status and Future Directions

Carotid Artery Stenting with Distal Protection Using the Carotid Wallstent and Filterwire Neuroprotection: Single-Center Experience of 380 Cases with Midterm Outcomes

Emerging data have supported the clinical efficacy of carotid artery stenting (CAS) in stroke prevention in high-risk surgical patients. This study was performed to evaluate the midterm clinical outcome of CAS using the Carotid Wallstent and FilterWire distal protection (both Boston Scientific, Natick, MA) at an academic institution. Risk factors for in-stent restenosis (ISR) were also analyzed. Clinical variables and treatment outcome of high-risk patients who underwent Carotid Wallstent placement with FilterWire EX/EZ neuroprotection were analyzed during a recent 54-month period. Three hundred eighty CAS procedures were performed in 354 patients. Technical success was achieved in 372 cases (98%), and symptomatic lesions existed in 85 (24%) patients. No patient experienced periprocedural mortality or neuroprotective device–related complication. The 30-day stroke and death rate was 2.7%, and the overall complication rate was 6.9%. The overall major or fatal stroke rates in symptomatic and asymptomatic patients were 4.6% and 1.3%, respectively (not significant). The overall stroke and death rates between the symptomatic and asymptomatic groups were 5.8% and 2.4%, respectively (not significant). The median follow-up period was 29 months (range 1–53 months). With Kaplan-Meier analysis, the rates of freedom from 60% or greater ISR after CAS procedures at 12, 24, 36, and 48 months were 97%, 94%, 92%, and 90%, respectively. The rates of freedom from all fatal and nonfatal strokes at 12, 24, 36, and 48 months were 97%, 91%, 89%, and 85%, respectively. Multivariable analysis of significant univariate predictors identified that postendarterectomy stenosis (odds ratio [OR] 3.98, p = .02) and multiple stent placement (OR 3.68, p = .03) were independent predictors of ISR. Our study yielded favorable short-term and midterm clinical results using Carotid Wallstent with FilterWire neuroprotection. Late follow-up results showed low rates of fatal and nonfatal stroke and favorable ISR rates compared with other carotid stent trials. Postendarterectomy and multiple stent placement were associated with subsequent ISR.

Experience of 500 cases of neurophysiological monitoring in carotid endarterectomy

BACKGROUND

Experience with Intraoperative monitoring using neurophysiological and haemodynamic indices in 500 operations for carotid endarterectomy is reported.

METHODS

Transcranial Doppler technique (TCD), electroencephalogram (EEG) and bilateral median somatosensory evoked potentials (SEP) were performed. Latency and amplitude of SEP, spectral analysis of EEG signal and blood flow velocity in the medial cerebral artery (MCA) were continuously measured.

FINDINGS

After two consecutive drops of N20/P25 complex of more than 50%, a warning was given, and when the decrease continued, an the alarm raised. Abnormal EEG changes, if any, appeared after a significant decrease in the N20/P25 amplitude. A mean blood flow velocity drop below 40% of the reference value after cross clamping was rated as a significant warning event.A warning as a result of a decrease in N20/P25 amplitude occurred in 80 operations (16.0%), after an spectral edge frequency decrease in 2 cases (0.4%) and after a V(mean) decrease in 21 cases (4.2%). False negative results were experienced in 2 patients (0.4%). A shunt was inserted in 2.8% of the operations. The overall mortality/morbidity rate was 2.4%.

CONCLUSION

A decrease of more than 50% in the amplitude of the thalamocortical somatosensory evoked potential complex N20/P25 proved to be the most reliable warning of danger of ischaemia during carotid endarterectomy.

Carotid artery stenting with neuroprotection: assessing the learning curve and treatment outcome

PURPOSE

Carotid artery stenting (CAS) has emerged as an acceptable treatment alternative in high-risk patients with carotid stenosis. The purpose of this study was to assess the effect of the learning curve on treatment complications and the clinical outcomes of CAS.

METHODS

Clinical variables and treatment outcomes of 200 consecutive CAS procedures in 182 patients (mean age 72 years) with carotid stenosis > or = 70% during a 40-month period were analyzed. Four sequential groups (groups I, II, III, and IV) of 50 consecutive interventions were compared with regard to technical success, periprocedural complications, and treatment outcomes.

RESULTS

Treatment indications and relevant risk factors were similar among the 4 groups. The overall technical success and combined 30-day stroke and death rates were 98% and 2.5%, respectively. An increase in the technical success rate was noted in the latter 3 groups compared with group I (P < .05). Total procedural time and contrast volume were significantly higher in group I compared with the latter 3 groups (P < .05). The intraoperative anticoagulation regimen was changed from intravenous heparin combination to bivalirudin after the first 54 patients, which resulted in decreased bleeding complications in groups III and IV (P = 0.03) compared with the first group. The 30-day stroke and death rate in groups I and II were 8% and 2%, respectively, and was decreased significantly in groups III and IV (0% and 0%, respectively, P < .05). A Cox regression model identified procedural volume (P = .03) as a predictor of decreased complication rate.

CONCLUSIONS

CAS with neuroprotection can provide excellent treatment outcomes. Our experience demonstrates a procedure-associated learning curve as evidenced by decreased procedure-related complications, fluoroscopic time, and contrast volume occurring with increased physician experience. Procedural success was also enhanced partly by endovascular device refinement and an improved anticoagulation regimen. Successful CAS outcomes can be achieved once physicians overcome the initial procedure-related learning curve.

Acute arterial emergencies: evaluation by Doppler ultrasound

Doppler ultrasonography is an easy accessible, safe and non-invasive diagnostic modality that may provide prompt and accurate diagnosis concerning an acute emergency of arterial origin. Although angiography is the gold standard in the evaluation of acute arterial pathologies, Doppler US may provide essential information regarding the acute arterial pathology. The aim of this manuscript is to review the current applications of Doppler sonography in acute arterial emergencies in light of recent advancements of sonographic and other imaging modalities.

Transcervical Approach With Protective Flow Reversal for Carotid Angioplasty and Stenting

PURPOSE

To report our initial experience using a transcervical approach for carotid angioplasty/stenting (CAS) that employs internal carotid artery (ICA) flow reversal for neuroprotection.

METHODS

Seventeen patients (15 men; mean age 65 years, range 49-77) with significant carotid stenosis (mean 88%, 8 symptomatic) were treated with protected transcervical CAS. Eleven patients were considered at high risk for carotid endarterectomy; 8 were also considered high risk for transfemoral access (unfavorable aortic arch anatomy or advanced aortoiliac occlusive disease). Anesthesia was based on patient and anesthesiologist preferences. The approach consisted of a 2-cm cutdown over the common carotid artery and placement of a 9-F sheath. ICA flow was reversed and shunted into the jugular vein during the carotid intervention.

RESULTS

Access and carotid stenting were successful in all cases. Thirteen procedures were performed under general and 4 under local anesthesia. Mean flow reversal time was 34+/-4 minutes (25 minutes in the last 7 cases). The patients tolerated the procedure well and had no neurological events. Four (23%) patients had significant oozing from the operative site; 2 developed small neck hematomas that were treated conservatively. All patients were discharged on the first postoperative day. There were no deaths, changes in neurological status, or restenosis over a mean follow-up of 12 months (range 1-24).

CONCLUSIONS

Our initial experience demonstrates that a transcervical approach is a viable alternative for CAS. The procedure can be performed safely, with good initial clinical outcomes. The approach allows carotid flow reversal and emboli protection without introducing neuroprotection devices. The method appears best suited for patients at high risk for endarterectomy and transfemoral access.

Nonsurgical carotid revascularization

Carotid endarterectomy is a well-established treatment of improving the carotid luminal diameter and preventing strokes, and the indications and complications are well-defined. Carotid angioplasty and stent placements are relatively newer ways of treating carotid artery stenosis. In certain contexts, they may have some advantages over carotid endarterectomy. However, the success rates, morbidity, and mortality associated with these procedures are less well characterized. In earlier comparative studies, the incidence of ipsilateral stroke rate was higher with angioplasty, but in later studies, this trend is reversing. Angioplasty may also have an edge in specific situations like patients with coexisting significant coronary arterial disease, contralateral carotid artery occlusion, and in instances when the narrowing is long and at multiple sites. Protective devices like distal occlusion balloon and filter protection devices may reduce the incidence of stroke. We are still awaiting the results of some major randomized head-to-head trials comparing carotid endarterectomy and stenting.

Feasibility of Stent Placement in Carotid Arteries with Real-time MR Imaging Guidance in Pigs

All examinations were performed with approval from the institutional animal care and use committee of Columbia University. To assess the feasibility of real-time magnetic resonance (MR) imaging-guided neurovascular intervention in a swine model, the authors placed stents in the carotid arteries of five domestic pigs. Seven-French vascular sheaths were placed in the target carotid arteries via femoral access by using active MR tracking. Ten nitinol stents (8-10 x 20-40 mm) were successfully deployed in the target segments of carotid arteries bilaterally. MR imaging and necropsy findings confirmed stent position. Necropsy revealed no gross vascular injury. Study results demonstrated the feasibility of performing real-time MR imaging-guided neurovascular intervention by using an active-tracking technique in an animal model.

Transfemoral catheterization of carotid arteries with real-time MR imaging guidance in pigs

All procedures and protocols were approved by the institutional animal care and use committee of Columbia University. To determine whether transfemoral catheterization of the carotid arteries can be performed entirely with real-time magnetic resonance (MR) imaging guidance, the authors catheterized the carotid arteries in six domestic pigs by using active-tracking catheters and guidewires and MR tracking software created for neurovascular procedures. The carotid arteries were successfully catheterized 24 times, on average within 5 minutes after insertion of the catheter into the femoral artery. Results demonstrated the feasibility of performing transfemoral catheterization of the carotid arteries with active MR tracking devices in a conventional MR imaging unit.