ACCF/SCAI/SVMB/SIR/ASITN 2007 Clinical Expert Consensus Document on Carotid Stenting

Usefulness of computed tomography angiography for the detection of high-risk aortas for carotid artery stenting

This study evaluated the usefulness of computed tomography (CT) angiography for the detection of high-risk aortas for carotid artery stenting (CAS). We investigated changes in the treatment method and modifications of endovascular techniques according to the information from CT angiography. CT angiography using three-dimensional and multi-planar reconstruction was performed in 43 consecutive patients with carotid artery stenoses intended to undergo CAS. Two neurosurgeons evaluated the images and estimated the risk and difficulties of CAS. CT angiography clearly depicted the entire aorta, the supra-aortic vessels, and the ilio-femoral arteries in all patients. Abnormal vascular findings were found in 17 patients. High-risk aortic lesions for CAS were detected in 5 patients, including thick aortic plaques with thrombi in 2. We changed the treatment strategy from CAS to carotid endarterectomy (CEA) in these 2 patients. CT angiograms proved very useful in evaluating the approach routes of CAS in 12 patients. One patient had dissecting aneurysm of the thoracic aorta and another had aberrant right vertebral artery. In these two, the treatment strategy was changed from CAS to CEA. The treatment method was changed in 4 patients in total. CT angiography is useful for the detection of high-risk aortas for CAS and for the evaluation of safe approaches to the carotid artery.

Treatment strategies in severe symptomatic carotid and coronary artery disease

Coexistent carotid artery stenosis (CS) and multivessel coronary artery disease (CAD) is not infrequent. One in 5 patients with multivessel CAD has a severe CS, and CAD incidence reaches 80% in those referred for carotid revascularization. We reviewed treatment strategies for concomitant severe CS and CAD.

We performed a literature search (MEDLINE) with terms including carotid artery stenting (CAS), coronary artery bypass grafting (CABG), carotid endarterectomy (CEA), stroke, and myocardial infarction (MI).

The main therapeutic option for CS-CAD has been (simultaneous or staged) CEA-CABG. This, however, is associated with a high risk of MI (in those with CEA prior to CABG) or stroke (CABG prior to CEA), and the cumulative major adverse event rate (MAE – death, stroke or MI) reaches 10–12%. With increasing adoption of CAS, a sequential strategy of CAS followed by CABG has emerged. Registries (usually single-centre) indicate an MAE rate of ≈7% for CAS followed by CABG (frequently after >30 days, due to double antiplatelet therapy). Recently, 1-stage CAS-CABG has been introduced. This involves different antiplatelet regimens and, in some centers, preferred off-pump CABG, with a cumulative MAE of 1.4–4.5%.

No randomized trial comparing different treatment strategies in CS-CAD has been conducted, and thus far reported series are prone to selection/reporting bias. In addition to the established surgical treatment (CEA-CABG, sequential/simultaneous), hybrid revascularization (CAS-CABG) is emerging as a viable therapeutic option. Larger, preferably multi-centre, studies are required before this can become widely applied.

Carotid stenting improves cognitive function in asymptomatic cerebral ischemia

OBJECTIVES

Asymptomatic critical internal carotid artery (ICA) stenosis may lead to cognitive impairment. Carotid stenting (CS) may improve cerebral perfusion, but its impact on neuro-cognitive function has been controversial.

METHODS

We prospectively enrolled 34 asymptomatic patients with unilateral ICA stenosis or occlusion, in whom CS was attempted. Computed tomography cerebral perfusion (CTP), and functional assessments including National Institutes of Health Stoke Scale (NIHSS), Bathel Index (BI), and a battery of neuropsychological tests including Mini-Mental State Examination (MMSE), Alzheimer Disease Assessment Scale-Cognitive Subtest (ADAS-Cog), verbal fluency, and Color Trail Making A and B, were done prior to and 3 months after the procedure.

RESULTS

Successful CS was achieved in 28 of 34 patients (82%). Based on the baseline CTP finding and intervention result, patients were divided into three groups: group I (n=6) as ipsilateral cerebral ischemia with failed CS procedure, group II (n=17) as ipsilateral cerebral ischemia with successful CS procedure, and group III (n=11) as normal baseline CTP with successful CS procedure. The demographics and baseline cognitive performances were similar among the three groups. In group II, there were significant improvement in Alzheimer Disease Assessment Scale (pre 6.8 ± 4.3 vs post 4.9 ± 2.8, p=0.033), Mini-Mental State Examination Score (pre 25.8 ± 3.8 vs post 27.4 ± 3.5, p=0.007), and Color Trail test A (pre 120.4 ± 73.9s vs post 95.8 ± 57.6s, p=0.004) after CS. In groups I and III, however, no significant difference was observed in any of the cognitive tests.

CONCLUSIONS

Successful CS improves neurocognitive function in asymptomatic ICA stenosis or occlusion with objective ipsilateral ischemia.

Comparative analysis of the biaxial mechanical behavior of carotid wall tissue and biological and synthetic materials used for carotid patch angioplasty

Patch angioplasty is the most common technique used for the performance of carotid endarterectomy. A large number of patching materials are available for use while new materials are being continuously developed. Surprisingly little is known about the mechanical properties of these materials and how these properties compare with those of the carotid artery wall. Mismatch of the mechanical properties can produce mechanical and hemodynamic effects that may compromise the long-term patency of the endarterectomized arterial segment. The aim of this paper was to systematically evaluate and compare the biaxial mechanical behavior of the most commonly used patching materials. We compared PTFE (n  =  1), Dacron (n  =  2), bovine pericardium (n  =  10), autogenous greater saphenous vein (n  =  10), and autogenous external jugular vein (n  =  9) with the wall of the common carotid artery (n  =  18). All patching materials were found to be significantly stiffer than the carotid wall in both the longitudinal and circumferential directions. Synthetic patches demonstrated the most mismatch in stiffness values and vein patches the least mismatch in stiffness values compared to those of the native carotid artery. All biological materials, including the carotid artery, demonstrated substantial nonlinearity, anisotropy, and variability; however, the behavior of biological and biologically-derived patches was both qualitatively and quantitatively different from the behavior of the carotid wall. The majority of carotid arteries tested were stiffer in the circumferential direction, while the opposite anisotropy was observed for all types of vein patches and bovine pericardium. The rates of increase in the nonlinear stiffness over the physiological stress range were also different for the carotid and patching materials. Several carotid wall samples exhibited reverse anisotropy compared to the average behavior of the carotid tissue. A similar characteristic was observed for two of 19 vein patches. The obtained results quantify, for the first time, significant mechanical dissimilarity of the currently available patching materials and the carotid artery. The results can be used as guidance for designing more efficient patches with mechanical properties resembling those of the carotid wall. The presented systematic comparative mechanical analysis of the existing patching materials provides valuable information for patch selection in the daily practice of carotid surgery and can be used in future clinical studies comparing the efficacy of different patches in the performance of carotid endarterectomy.

Subcutaneous hematoma associated with manual cervical massage during carotid artery stenting. A case report

We describe a patient with subcutaneous hematoma associated with manual cervical massage during carotid artery stenting.A 73-year-old man with left cervical carotid artery stenosis presented with left amaurosis fugax. We performed carotid artery stenting using distal embolic protection with balloon occlusion. Dual antiplatelet therapy was maintained in the periprocedural period and an anticoagulant agent was administered during the procedure. Because the aspiration catheter became entrapped by the stent, it did not reach the distal side of the stenotic lesion, and manual compression of the cervical region was therefore performed. Immediately afterwards, a subcutaneous hemorrhage occurred in the cervical region. There was no postoperative dyspnea due to enlargement of the hematoma, which was absorbed spontaneously.Cervical subcutaneous hematoma can occur in the cervical region due to cervical massage in patients who are receiving adjuvant antiplatelet therapy and anticoagulation therapy.

Reproducibility of IVUS border detection for carotid atherosclerotic plaque assessment

Plaque composition is a potentially important diagnostic feature for carotid artery stenting (CAS). The purpose of this investigation is to evaluate the reproducibility of manual border correction in intravascular ultrasound with virtual histology (VH IVUS) images. Three images each were obtained from 51 CAS datasets on which automatic border detection was corrected manually by two trained observers. Plaque was classified using the definitions from the CAPITAL (Carotid Artery Plaque Virtual Histology Evaluation) study, listed in order from least to most pathological: no plaque, pathological intimal thickening, fibroatheroma, fibrocalcific, calcified fibroatheroma, thin-cap fibroatheroma, and calcified thin-cap fibroatheroma. Inter-observer variability was quantified using both weighted and unweighted Kappa statistics. Bland-Altman analysis was used to compare the cross-sectional areas of the vessel and lumen. Agreement using necrotic core percentage as the criterion was evaluated using the unweighted Kappa statistic. Agreement between classifications of plaque type was evaluated using the weighted Kappa statistic. There was substantial agreement between the observers based on necrotic core percentage (κ=0.63), while the agreement was moderate (κ(quadratic)=0.60) based on plaque classification. Due to the time-consuming nature of manual border detection, an improved automatic border detection algorithm is necessary for using VH IVUS as a diagnostic tool for assessing the suitability of patients with carotid artery occlusive disease for CAS.

Operator experience and carotid stenting outcomes in Medicare beneficiaries

CONTEXT

Although the efficacy of carotid stenting has been established in clinical trials, outcomes of the procedure based on operator experience are less certain in clinical practice.

OBJECTIVE

To assess association between outcomes and 2 measures of operator experience: annual volume and experience at the time of the procedure among new operators who first performed carotid stenting after a national coverage decision by the Centers for Medicare & Medicaid Services (CMS).

DESIGN, SETTING, AND PATIENTS

Observational study using administrative data on fee-for-service Medicare beneficiaries aged 65 years or older undergoing carotid stenting between 2005 and 2007.

MAIN OUTCOME MEASURE

Thirty-day mortality stratified by very low, low, medium, and high annual operator volumes (<6, 6-11, 12-23, and ≥24 procedures per year, respectively) and treatment early vs late during a new operator's experience (1st to 11th procedure and 12th procedure or higher).

RESULTS

During the study period, 24,701 procedures were performed by 2339 operators. Of these, 11,846 were performed by 1792 new operators who first performed carotid stenting after the CMS national coverage decision. Overall, 30-day mortality was 1.9% (n = 461) and rate of failure to use an embolic protection device was 4.8% (n = 1173). The median annual operator volume among Medicare beneficiaries was 3.0 per year (interquartile range, 1.4-6.5) and 11.6% of operators performed 12 or more procedures per year during the study period. Observed 30-day mortality was higher among patients treated by operators with lower annual volumes (2.5% [95% CI, 2.1%-2.9%], 1.9% [95% CI, 1.6%-2.3%], 1.6% [95% CI, 1.3%-1.9%], and 1.4% [95% CI, 1.1%-1.7%] across the 4 categories; P < .001) and among patients treated early (2.3%; 95% CI, 2.0%-2.7%) vs late (1.4%; 95% CI, 1.1%-1.9%; P < .001) during a new operator's experience. After multivariable adjustment, patients treated by very low-volume operators had a higher risk of 30-day mortality compared with patients treated by high-volume operators (adjusted odds ratio, 1.9; 95% CI, 1.4-2.7; P < .001). Similarly, we found a higher risk of 30-day mortality in patients treated early vs late during a new operator's experience (adjusted odds ratio, 1.7; 95% CI, 1.2-2.4; P = .001).

CONCLUSION

Among older patients undergoing carotid stenting, lower annual operator volume and early experience are associated with increased 30-day mortality.

Carotid stenting or carotid surgery in average surgical-risk patients: interpreting the conflicting clinical trial data

There are generic as well as carotid-specific trial design considerations that have the potential to materially affect the outcomes and interpretation of comparative studies between carotid artery stenting and carotid endarterectomy. Recently, a series of trials in patients who are at average risk for carotid surgery have been reported. The European trials have all suffered from allowing an imbalance in operator experience between stenting and surgery and have consistently allowed stenting procedures without embolic protection. The combination of inexperienced operators and lack of embolic protection may be responsible for their negative stenting results. The Carotid Revascularization with Endarterectomy vs. Stenting Trial avoided both of these problems, having a threshold of experience for operators as well as mandating embolic protection be used. The Carotid Revascularization with Endarterectomy vs. Stenting Trial demonstrated noninferiority for stenting compared with surgery in average-risk symptomatic and asymptomatic patients, leading to Food and Drug Administration approval of a stent and protection for this indication. This has been recently followed by guidelines supporting the role of stenting compared with surgery from a broad range of professional societies.

The association of clinical variables and filter design with carotid artery stenting thirty-day outcome

OBJECTIVE

Patient and device selection are important for the success of carotid artery stenting (CAS). We hypothesize that distal protection filter (DPF) design characteristics that minimize blood flow resistance and maximize capture efficiency are associated with the absence of transient ischemic attack (TIA), stroke and neurologic-related death after 30 days.

METHODS

Records from 208 patients were reviewed retrospectively. Filter design characteristics were quantified previously in our laboratory. The association between risk factors and design characteristics with 30-day outcome was quantified using univariate analysis.

RESULTS

The 30-day all-cause stroke and death rate was 8.7% (asymptomatic: 7.7%, symptomatic: 10.6%). Five DPFs were used in the study: Accunet (41.3%), Angioguard (33.2%), FilterWire (24%), Emboshield (1%), and Spider (.5%). Diabetes (P = .04) and prior carotid endarterectomy (CEA, P = .03) were associated with adverse outcome. Prior stroke (P = .01) and prior CEA (P = .04) were significant for peri-procedural stroke. Design characteristics such as capture efficiency were associated with favorable outcomes.

CONCLUSIONS

Patients with prior CEA or stroke are more likely to have unfavorable CAS outcomes after 30 days. Filters with high capture efficiency may yield the best clinical results. Analysis of the effect of design characteristics on CAS outcome should aid the design of future devices.

Physician specialty and carotid stenting among elderly medicare beneficiaries in the United States

BACKGROUND

The use of carotid stenting is rising across the United States. How physician specialty relates to its utilization rates or outcomes is uncertain.

METHODS

We performed an observational analysis of fee-for-service Medicare beneficiaries 65 years or older undergoing carotid stenting between 2005 and 2007 in 306 hospital referral regions (HRRs). We first determined how frequently carotid stenting was performed by different specialists within each HRR and then used multivariable regression models to compare population-based utilization rates and 30-day outcomes for this procedure across HRRs based on the proportion performed by cardiologists, surgeons, radiologists, or a mix of specialists.

RESULTS

In 272 HRRs where at least 15 procedures were performed during the study period, we identified 28 700 carotid stenting procedures performed by 2588 operators. While cardiologists made up approximately one-third of these operators, they were responsible for 14 919 (52.0%) procedures. Significant differences were noted in the characteristics of patients treated by cardiologists compared with other specialties, including higher rates of invasive cardiac procedures and lower rates of acute stroke or transient ischemic attacks in the 180 days prior to carotid stenting. Population-based utilization rates were significantly higher in HRRs where cardiologists performed most procedures relative to HRRs where most were done by other specialists or a mix of specialists (P < .001). In contrast, risk-standardized outcomes did not differ across HRRs based on physician specialty.

CONCLUSIONS

Carotid stenting is being performed by operators from diverse specialties. Hospital referral regions where cardiologists perform most procedures have higher population-based utilization rates with similar outcomes.

Stroke prevention-surgical and interventional approaches to carotid stenosis

Extracranial carotidartery stenosis is an important cause of stroke that often needs treatment with carotid revascularization. To prevent stroke recurrence, carotid endarterectomy has been well-established for many years in treating symptomatic high- and moderate-grade stenosis. Carotid stenting is an appealing, less invasive alternative to carotid endarterectomy, and several recent trials have compared the efficacy of the 2 procedures in patients with carotid stenosis. Carotid artery stenting has emerged as an important mode of therapy for high-risk patients with symtomatic high-grade stenosis. This review focuses on the current data available that will enable the clinician to decide optimal treatment strategies for patients with carotid stenosis.

Experimental determination of circumferential properties of fresh carotid artery plaques

Carotid endarterectomy (CEA) is currently accepted as the gold standard for interventional revascularisation of diseased arteries belonging to the carotid bifurcation. Despite the proven efficacy of CEA, great interest has been generated in carotid angioplasty and stenting (CAS) as an alternative to open surgical therapy. CAS is less invasive compared with CEA, and has the potential to successfully treat lesions close to the aortic arch or distal internal carotid artery (ICA). Following promising results from two recent trials (CREST; Carotid revascularisation endarterectomy versus stenting trial, and ICSS; International carotid stenting study) it is envisaged that there will be a greater uptake in carotid stenting, especially amongst the group who do not qualify for open surgical repair, thus creating pressure to develop computational models that describe a multitude of plaque models in the carotid arteries and their reaction to the deployment of such interventional devices. Pertinent analyses will require fresh human atherosclerotic plaque material characteristics for different disease types. This study analysed atherosclerotic plaque characteristics from 18 patients tested on site, post-surgical revascularisation through endarterectomy, with 4 tissue samples being excluded from tensile testing based on large width-length ratios. According to their mechanical behaviour, atherosclerotic plaques were separated into 3 grades of stiffness. Individual and group material coefficients were then generated analytically using the Yeoh strain energy function. The ultimate tensile strength (UTS) of each sample was also recorded, showing large variation across the 14 atherosclerotic samples tested. Experimental Green strains at rupture varied from 0.299 to 0.588 and the Cauchy stress observed in the experiments was between 0.131 and 0.779 MPa. It is expected that this data may be used in future design optimisation of next generation interventional medical devices for the treatment and revascularisation of diseased arteries of the carotid bifurcation.

Jaw claudication in the era of carotid stenting

Jaw claudication could result from external carotid artery (ECA) occlusive disease. Carotid artery stenting (CAS) has been shown to worsen the disease in the ECA. This could potentially worsen the symptoms in patients with pre-existing jaw claudication undergoing CAS. Meanwhile, ECA endarterectomy is routinely done during internal carotid artery endarterectomy (CEA). This has been shown to alleviate jaw claudication symptoms. We report a case of a high-risk patient for CEA who presented with symptomatic carotid disease as well as bilateral jaw claudication. Both symptoms resolved after CEA. We also present the case of another patient treated for recurrent high-grade carotid disease with CAS resulting in acute ECA occlusion and jaw claudication. High-risk patients with symptomatic carotid disease and jaw claudication should be considered for CEA and not only CAS.

Carotid artery disease and stenting: insights from recent clinical trials

OPINION STATEMENT

Cerebrovascular disease remains a leading cause of morbidity, mortality, and health care expenditure in the United States. Approximately 80% of strokes are ischemic in origin, with 20% to 25% due to atherosclerotic disease of the carotid artery. It is well established that untreated, symptomatic carotid stenosis confers a 25% risk of stroke within 2 years, and that asymptomatic carotid stenosis > 60% is associated with an 11% stroke risk at 5 years. Over the past six decades, surgical revascularization with carotid endarterectomy, when performed by experienced surgeons, has been demonstrated to be effective in reducing stroke risk in patients with severe stenosis. During the same time, medical therapy has improved considerably, and endovascular therapy with carotid angioplasty and stenting has emerged as an important alternative strategy that may play a significant role in reducing the risk of stroke in patients with carotid disease. In this review, we examine the current evidence regarding optimal medical therapy, endarterectomy, and stenting for the management of patients with carotid stenosis. Armed with these data, we may tailor our approach to optimize care based on patient- and lesion-specific considerations.

Clinical Referral Patterns for Carotid Artery Stenting Versus Carotid Endarterectomy

Background—

Carotid artery stenting (CAS) and carotid endarterectomy (CEA) are alternative strategies for stroke prevention in patients with atherosclerotic carotid disease. Although randomized clinical trials are the gold standard for assessing the relative benefits of different treatments, observational research is necessary for determining “real-world” effectiveness. Current recommendations limit the application of CAS to high-risk patients, undermining the ability to “balance” the characteristics of patients treated with either approach. We compared the clinical profiles of patients referred for CAS versus CEA in a large national database.

Methods and Results—

Clinical characteristics of 12 701 patients referred for CAS or CEA in the National Cardiovascular Data Registry–Carotid Artery Revascularization and Endarterectomy were compared for 44 clinical and demographic variables. To investigate the comparability of CAS and CEA patients, we stratified the cohort into quintiles of the propensity score for referral for CAS. Among 8069 patients referred for CAS and 4632 referred for CEA, the CAS patients had significantly more comorbidities. Whereas the propensity model balanced most covariates, the pooled standardized differences (≥10%) suggested persistent imbalance for ischemic heart disease, recent myocardial infarction, and restenosis of prior CAS/CEA, all of which were more common in the CAS group. After stratification of propensity scores by quintile, CEA patients comprised only 14% of the upper 2 quintiles.

Conclusions—

Characteristics of patients referred for CAS differ markedly from those referred for CEA. Because of extreme clinical disparities between these patients, generalizable comparative effectiveness analyses of observational data will be difficult.

Does current practice in the United States of carotid artery stent placement benefit asymptomatic octogenarians?

BACKGROUND AND PURPOSE

CAS or CEA for asymptomatic carotid stenosis is the focus of recently completed and ongoing randomized clinical trials. These techniques are widely utilized outside the setting of such trials. Therefore, our goal was to analyze the in-hospital stroke or death rates after CAS or CEA for asymptomatic stenosis that reflect current nationwide practice.

MATERIALS AND METHODS

Using sample-weighted ANOVA, we analyzed records from the 2006 and 2007 NIS, which are nationally representative cohorts for asymptomatic CAS or CEA. The primary outcome measure was a composite end point of in-hospital stroke, cardiac complications, or death. In-hospital stroke or death was a secondary outcome measure.

RESULTS

For ≥ 80 years of age, the in-hospital stroke, cardiac complications, or death rate after CAS was 4.9%, while the complication rate after CEA was 3.8%. The stroke or death rate after CAS was 2.7% for ≥ 80 years of age and was 1.5% after CEA for the same age group. Multivariate analysis showed that age (OR, 1.12; 95% CI, 0.97-1.3; P < .07) or procedure (OR, 1.12; 95% CI, 0.99-1.27; P < .14) was not associated with the composite end point of in-hospital stroke, cardiac complications, or death. In contrast, CAS (OR, 1.28; 95% CI, 1.03-1.58) and female sex (OR, 1.23; 95% CI, 1.04-1.45) were independently associated with in-hospital stroke or death following asymptomatic carotid revascularization. Hospital charges and hospital costs were lower for CEA than CAS (2007 costs: $7779 versus $12,104).

CONCLUSIONS

CAS is independently associated with increased in-hospital stroke or death (excluding cardiac complications from the composite outcome). In those ≥ 80 years of age, CAS as currently performed may not improve the natural history of asymptomatic carotid stenosis, because in-hospital stroke or death rates following CAS approached 3% in this group.

Computational modeling of distal protection filters

PURPOSE

To quantify the relationship between velocity and pressure gradient in a distal protection filter (DPF) and to determine the feasibility of modeling a DPF as a permeable surface using computational fluid dynamics (CFD).

METHODS

Four DPFs (Spider RX, FilterWire EZ, RX Accunet, and Emboshield) were deployed in a single tube representing the internal carotid artery (ICA) in an in vitro flow apparatus. Steady flow of a blood-like solution was circulated with a peristaltic pump and compliance chamber. The flow rate through each DPF was measured at physiological pressure gradients, and permeability was calculated using Darcy's equation. Two computational models representing the RX Accunet were created: an actual representation of the filter geometry and a circular permeable surface. The permeability of RX Accunet was assigned to the surface, and CFD simulations were conducted with both models using experimentally derived boundary conditions.

RESULTS

Spider RX had the largest permeability while RX Accunet was the least permeable filter. CFD modeling of RX Accunet and the permeable surface resulted in excellent agreement with the experimental measurements of velocity and pressure gradient. However, the permeable surface model did not accurately reproduce local flow patterns near the DPF deployment site.

CONCLUSION

CFD can be used to model DPFs, yielding global flow parameters measured with bench-top experiments. CFD models of the detailed DPF geometry could be used for "virtual testing" of device designs under simulated flow conditions, which would have potential benefits in decreasing the number of design iterations leading up to in vivo testing.

Carotid artery stenting simulation: from patient-specific images to finite element analysis

The outcome of carotid artery stenting (CAS) depends on a proper selection of patients and devices, requiring dedicated tools able to relate the device features with the target vessel. In the present study, we use finite element analysis to evaluate the performance of three self-expanding stent designs (laser-cut open-cell, laser-cut closed-cell, braided closed-cell) in a carotid artery (CA). We define six stent models considering the three designs in different sizes and configurations (i.e. straight and tapered), evaluating the stress induced in the vessel wall, the lumen gain and the vessel straightening in a patient-specific CA model based on computed angiography tomography (CTA) images. For the considered vascular anatomy and stents, the results suggest that: (i) the laser-cut closed-cell design provides a higher lumen gain; (ii) the impact of the stent configuration and of the stent oversizing is negligible with respect to the lumen gain and relevant with respect to the stress induced in the vessel wall; (iii) stent design, configuration and size have a limited impact on the vessel straightening. The presented numerical model represents a first step towards a quantitative assessment of the relation between a given carotid stent design and a given patient-specific CA anatomy.

Scar formation in the carotid sheath identified during carotid endarterectomy in patients with previous cardiac surgery: significance of history of intraoperative Swan-Ganz catheter insertion. Clinical article

OBJECT

Scar formation in the carotid sheath is often identified during carotid endarterectomy (CEA) in patients with previous cardiac surgery, and dissection of the carotid sheath and exposure of the carotid arteries in such patients are difficult. The purpose of the present study was to investigate factors related to scar formation identified during CEA in patients with previous cardiac surgery.

METHODS

Twenty-three patients with internal carotid artery stenosis (≥ 70%) and previous cardiac surgery underwent CEA. A patient was prospectively defined as having scar formation during CEA when scissors were required throughout dissection of the carotid sheath and exposure of the carotid arteries.

RESULTS

Scar formation was identified during dissection of the carotid sheath in 7 patients (30.4%). In all 7 patients, the side of CEA was identical to the side on which the Swan-Ganz catheter was inserted during cardiac surgery, and the incidence of previous ipsilateral Swan-Ganz catheter insertion was significantly higher in patients with the scar formation (100%) than in those without (31.3%). Seven (58.3%) of 12 patients with a history of ipsilateral Swan-Ganz catheter insertion had scar formation. Two of the 7 patients with scar formation experienced complications after CEA, including one patient with hemiparesis due to artery-to-artery embolism during surgery, and another patient with transient vocal cord paralysis.

CONCLUSIONS

A history of Swan-Ganz catheter insertion during previous cardiac surgery is associated with the presence of scar tissue in the ipsilateral carotid sheath and a higher risk of complications during CEA.

Comparison of rotational with conventional coronary angiography

BACKGROUND

Patient radiation exposure and consumption of contrast medium are considered major risks of diagnostic coronary angiography (CA). Rotation of the C-arm during CA could provide similar diagnostic accuracy and lower radiation exposure and contrast medium consumption.

METHODS

To compare feasibility, safety, diagnostic accuracy, patient radiation exposure, and consumption of contrast medium of rotational CA with the invasive standard technique, intraindividual comparisons of the results obtained by both techniques were performed in 235 patients with an indication for first-time elective CA. In addition to conventional angiography, we performed 2 isocentric radiographic coronary spins with cranial and caudal tilts by 20 degrees around the left coronary artery and 1 strict posteroanterior rotational spin around the right coronary artery.

RESULTS

In 16 patients, rotational CA was not performed because of safety concerns. In a further 12 patients, image quality of rotational scans was considered inadequate. In the remaining 207 patients, both modes of CA were proven suitable for anonymized, separate analysis by 3 independent cardiologists. Intraindividual comparison of both CA modes revealed a high degree of diagnostic agreement (Cohen (K) >0.8 for all cardiologists and for each coronary segment). Contrast medium volume during rotational CA and conventional CA amounted to 31.9 +/- 4.5 mL versus 52.2 +/- 8.0 mL (P < .001) and patient radiation exposure amounted to 5.0 +/- 2.6 Gy × cm(2) versus 11.5 +/- 5.5 Gy × cm(2) (P < .001), respectively.

CONCLUSIONS

Rotational CA represents a safe and feasible method in clinical routine. Whereas diagnostic accuracy is similar to the usual conventional mode, consumption of contrast medium and patient radiation exposure are significantly reduced.

Simple immersion of filter devices into an urokinase solution prevents fibrin net formation during carotid artery stenting

Slow-flow phenomenon is frequently observed during carotid artery stenting (CAS) with a filter embolic protection device. It results in technical difficulties and can lead to adverse neurological events. Flow impairment is thought to be caused by plaque entrapped by the filter and/or blood coagulation on the filter. Characteristics of heparin- or urokinase-treated polyurethanes were analyzed by surface plasmon resonance, and the fibrinolytic activity of the urokinase-treated filter of Angioguard XP was estimated by the fibrin plate assay. A filter membrane of Angioguard XP protection device was treated with a heparin or urokinase solution. In clinical studies, six and nine patients were treated by CAS using Angioguard XP modified with heparin and urokinase, respectively. Filter membranes were examined by scanning electron microscopy (SEM). From in vitro studies, it appeared that urokinase adsorbed and remained on the Angioguard XP filter, and its fibrinolytic activity was demonstrated even after washing with saline; heparin, however, was easily washed out from the surface. From clinical study, some filter pores were obstructed in all six patients in the heparin group and in three patients in the urokinase group. Fibrin net was found on the filter in five of six patients in the heparin group and in one of nine patients in the urokinase group. Treatment of an Angioguard XP filter with a urokinase solution is effective in preventing pore occlusion and may reduce occurrence of the slow-flow phenomenon.

Carotid artery stenting in high surgical risk patients using the FiberNet embolic protection system: the EPIC trial results

OBJECTIVE

The multicenter EPIC (FiberNet Embolic Protection System in Carotid Artery Stenting Trial) single-arm trial evaluated the 30-day outcomes of a new design concept for embolic protection during carotid artery stenting (CAS).

BACKGROUND

Embolic protection filters available for use during CAS include fixed and over-the-wire systems that rely on embolic material capture within a "basket" structure. The FiberNet Embolic Protection System (EPS), which features a very low crossing profile, consists of a three-dimensional fiber-based filter distally mounted on a 0.014 inch guidewire with integrated aspiration during filter retrieval.

METHODS

The trial enrolled 237 patients from 26 centers. Demographics, clinical and lesion characteristics, as well as adverse events through a 30-day follow-up were recorded. The mean age of the patients was 74 years, 64% were male and 20% had symptomatic carotid artery disease.

RESULTS

The combined major adverse event (MAE) rate at 30 days for all death, stroke, and myocardial infarction was 3.0%. There were three major strokes (two ischemic and one hemorrhagic) and two minor strokes (both ischemic) for a 2.1% 30-day stroke rate. The procedural technical success rate was 97.5% and macroscopic evidence of debris was reported in 90.9% of the procedures.

CONCLUSIONS

The FiberNet EPS, used with commercially available stents, produced low stroke rates following CAS in high surgical risk patients presenting with carotid artery disease. The unique filter design including aspiration during retrieval may have contributed to the low 30-day stroke rate reported during CAS in patients considered at high risk for complications following carotid endarterectomy (CEA).

Clinical cerebrovascular anatomy

Stroke is often the result of carotid atheroma, which may cause ischemia via progressive arterial narrowing or lead to superimposed thrombus formation and subsequent atheroembolism to the intracerebral vasculature. Revascularization through carotid endarterectomy or carotid artery stenting with embolic protection devices has produced favorable results in appropriately selected patients. In planning the percutaneous approach, an arch aortogram is first acquired to determine arch type and identify the presence of any anatomic variants which may affect the approach to the procedure and catheter selection. Subsequent imaging of the cerebral vasculature is performed to delineate the collateral circulation that is present, including an evaluation of the Circle of Willis. Although Doppler ultrasound, computed tomography (CT), and magnetic resonance angiography (MRA) may be useful in evaluating the presence of carotid or cerebrovascular disease, digital subtraction angiography is required prior to performance of a percutaneous intervention in order to create a procedural "roadmap". Additionally, the comprehensive management of cerebrovascular disease requires a detailed knowledge of the specific clinical syndromes that result from ischemia in each vascular territory. This methodical review of cerebrovascular anatomy and stroke syndromes will provide the operator with the tools to conduct a thorough neurological assessment prior to revascularization, evaluate any periprocedural complications that may arise, and evaluate the patient with suspected stroke.

Clinical features and outcomes of carotid artery stenting by clinical expert consensus criteria: a report from the CARE registry

BACKGROUND

In 2007, a multispecialty society task force published a clinical expert consensus document (CECD) on carotid stenting (CAS), containing recommendations for appropriate patient selection and quality of care. The CECD also inspired creation of a large, national registry of carotid revascularization, the Carotid Artery Revascularization and Endarterectomy (CARE) registry. Our goal here was to investigate whether initial CAS procedures submitted to CARE conformed to CECD recommendations, and examine their clinical outcomes.

METHODS

We analyzed CAS procedures for the period January 1, 2005 through December 31, 2008. These were grouped into those that conformed to CECD recommendations [CECD(+), n = 4,636, 79.8%] and those that did not [CECD(-), n = 1,168, 20.2%].

RESULTS

The CECD(+) patients were older than CECD(-) patients (71.5 +/- 10.3 vs. 67.6 +/- 10.3 years, P = 0.001, respectively), and more frequently had chronic kidney disease (46.9% vs. 17.8%, P = 0.001), chronic lung disease (33.0% vs. 12.4%, P = 0.001), ejection fraction <or= 0.30 (13.5% vs. 5.5%, P = 0.001) and contralateral carotid artery occlusion (12.7% vs. 4.6%, P = 0.001). Clinical outcomes at 30 days were similar, including death (1.24% vs. 0.76%, P = 0.184), stroke (5.32% vs. 5.34%, P = 0.954), and death, stroke, or MI (7.04% vs. 6.95%, P = 0.944).

CONCLUSIONS

Most CAS procedures submitted to CARE conformed to CECD recommendations for patient selection. For reported data, clinical outcomes at 30 days were similar for procedures meeting and those not meeting recommendations, and were similar to outcomes reported by other large registries. These findings suggest that acceptable patient selection criteria for CAS are employed as it expands beyond investigators into more widespread clinical practice.

Proximal endovascular occlusion for carotid artery stenting: results from a prospective registry of 1,300 patients

OBJECTIVES

This single-center registry presents the results of proximal endovascular occlusion (PEO) use in an unselected patient population.

BACKGROUND

In published multicenter registries, the use of PEO for carotid artery stenting (CAS) has been demonstrated to be safe and efficient in patient populations selected for anatomical and/or clinical conditions.

METHODS

From July 2004 to May 2009, 1,300 patients underwent CAS using PEO. Patients received an independent neurological assessment before the procedure and 1 h, 24 h, and 30 days after the procedure.

RESULTS

Procedural success was achieved in 99.7% of patients. In hospital, major adverse cardiac or cerebrovascular events included 5 deaths (0.38%), 6 major strokes (0.46%), 5 minor strokes (0.38%), and no acute myocardial infarction. At 30 days of follow-up, 2 additional patients died (0.15%), and 1 patient had a minor stroke (0.07%). The 30-day stroke and death incidence was 1.38% (n = 19). Symptomatic patients presented a higher 30-day stroke and death incidence when compared with asymptomatic patients (3.04% vs. 0.82%; p < 0.05). No significant difference in 30-day stroke and death rate was observed between patients at high (1.88%; n = 12) and average surgical risk (1.07; n = 7) (p = NS). Operator experience, symptomatic status, and hypertension were found to be independent predictors of adverse events.

CONCLUSIONS

The use of PEO for CAS is safe and effective in an unselected patient population. Anatomical and/or clinical conditions of high surgical risk were not associated with an increased rate of adverse events.

Indications and applications for extracranial carotid artery stent placement

Treatment of high-grade symptomatic carotid stenosis via carotid endarterectomy has been shown to be superior to medical management alone in several studies. Carotid angioplasty and stenting (CAS) has emerged as an alternative approach to endarterectomy to reduce the associated perioperative risks. Several anatomic and physiologic factors that increase the risk of stroke and/or death associated with endarterectomy have been identified. The alternative approach of CAS has been found to be noninferior to endarterectomy for high surgical risk patients with severe symptomatic carotid stenosis and the use of this procedure is supported by the current widely accepted guidelines. In patients with standard surgical risk, the differential benefit of CAS compared with endarterectomy is not clear. Several advantages of CAS have been identified in previous studies in selected patients. The results of CAS will undoubtedly continue to improve with advances in device designs, technological expertise, and appropriate patient selection.

Stroke prevention: carotid stenting versus carotid endarterectomy

Revascularization of the extracranial carotid arteries is a commonly performed surgical procedure to prevent stroke. Open surgery (i.e., carotid endarterectomy [CEA]) is a well-established stroke prevention procedure but is being ‘challenged' by a less invasive percutaneous procedure (i.e., carotid artery stent [CAS] placement). Clinical trials comparing CAS and CEA for average-surgical-risk patients have demonstrated mixed results, whereas the data for CAS compared with CEA in high-surgical-risk patients have demonstrated non-inferiority. The impending Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) results will have a major impact on the utility of CAS relative to CEA in average-surgical-risk patients.

In stent restenosis predictors after carotid artery stenting

Purpose. The long-term efficacy of carotid artery stenting is debated. Predictors of stent restenosis are not fully investigated. Our aim was to assess the incidence of long term restenosis after CAS and to identify some predictors of restenosis. Methods. We retrospectively selected 189 treated patients and we obtained the survival Kaplan-Meier curves for overall survival, for freedom from stroke or death and from restenosis. To correlate clinical, radiological, and procedural variables to stent restenosis, an univariate analysis was performed while to determine independent predictors of restenosis, a multivariate analysis was applied. Results. At 1, 3, and 5 years, the cumulative overall survival rate was 98%, 94%, and 92% with a cumulative primary patency rate of 87%, 82.5%, and 82.5%. The percentage residual stenosis after CAS and multiple stents deployment were independent predictors of restenosis, while diabetes and tumors are suggestive but not significant predictors of restenosis. Conclusions. In our CAS experience, encouraging long-term results seem to derive from both neurological event free rate and restenosis incidence. Adequate recanalization of the treated vessel is important to limit the development of stent restenosis. Multiple stents deployment, and with less evidence, diabetes, or neoplasms has to be considered to facilitate restenosis.