Grading Carotid Intrastent Restenosis

Duplex Ultrasound in Evaluating Transplanted Renal Artery In-Stent Restenosis

OBJECTIVE

To evaluate the diagnosis performance of duplex ultrasound (DUS) in predicting transplanted renal artery (TRA) in-stent restenosis (ISR).

METHODS

In this retrospective study, 112 consecutive patients underwent stenting due to TRA stenosis. DUS were performed within 1 week after stenting for baseline value, and after ≥3 months follow-up for surveillance of ISR. The DUS measurements included peak systolic velocity (PSV) and PSV ratio of renal artery stent to iliac artery (RIR). Receiver operating characteristic (ROC) curves were applied to evaluate the diagnosis performance of DUS parameters in predicting ISR.

RESULTS

There were 69 patients (28 men; age, 38.3 ± 15.1 years) who obtained 92 adequate paired DUS and CTA after stenting, which were classified as ISR group (26 TRAs) and non-ISR group (66 TRAs). There was no difference between the two groups for baseline DUS features, including PSVB and RIRB. The late DUS features including stent PSVL (475.5 vs 261.9 cm/s), RIRL (4.10 vs 2.18), and stent PSVL/PSVB (2.72 vs 1.14) were significantly higher in the ISR group than the non-ISR group (all P < .0001). Stent PSVL, RIRL, and PSVL/PSVB demonstrated comparable AUCs in predicting ISR. However, the sensitivity and specificity of PSVL/PSVB in predicting ISR were 92.3 and 93.5%, respectively, demonstrating higher specificity with equivalent sensitivity than PSVL and higher sensitivity with equivalent specificity than RIRL.

CONCLUSIONS

DUS is an accurate technique to identify TRA-ISR. We suggest all patients should undergo DUS immediately after stenting to establish baseline value and aid in evaluating ISR at late follow-up.

Stroke risk management in carotid atherosclerotic disease: a clinical consensus statement of the ESC Council on Stroke and the ESC Working Group on Aorta and Peripheral Vascular Diseases

Carotid atherosclerotic disease continues to be an important cause of stroke, often disabling or fatal. Such strokes could be largely prevented through optimal medical therapy and carotid revascularization. Advancements in discovery research and imaging along with evidence from recent pharmacology and interventional clinical trials and registries and the progress in acute stroke management have markedly expanded the knowledge base for clinical decisions in carotid stenosis. Nevertheless, there is variability in carotid-related stroke prevention and management strategies across medical specialities. Optimal patient care can be achieved by (i) establishing a unified knowledge foundation and (ii) fostering multi-specialty collaborative guidelines. The emergent Neuro-Vascular Team concept, mirroring the multi-disciplinary Heart Team, embraces diverse specializations, tailors personalized, stratified medicine approaches to individual patient needs, and integrates innovative imaging and risk-assessment biomarkers. Proposed approach integrates collaboration of multiple specialists central to carotid artery stenosis management such as neurology, stroke medicine, cardiology, angiology, ophthalmology, vascular surgery, endovascular interventions, neuroradiology, and neurosurgery. Moreover, patient education regarding current treatment options, their risks and advantages, is pivotal, promoting patient's active role in clinical care decisions. This enables optimization of interventions ranging from lifestyle modification, carotid revascularization by stenting or endarterectomy, as well as pharmacological management including statins, novel lipid-lowering and antithrombotic strategies, and targeting inflammation and vascular dysfunction. This consensus document provides a harmonized multi-specialty approach to multi-morbidity prevention in carotid stenosis patients, based on comprehensive knowledge review, pinpointing research gaps in an evidence-based medicine approach. It aims to be a foundational tool for inter-disciplinary collaboration and prioritized patient-centric decision-making.

Carotid Ultrasound

Carotid ultrasound is the primary noninvasive method for detecting, grading, and monitoring internal carotid artery (ICA) stenosis. Major components of carotid Doppler ultrasound include assessment of ICA stenosis using Doppler velocity criteria, spectral waveform analysis, and assessment of ICA stenosis. Recently, the Intersocietal Accreditation Commission Vascular Testing put forth new modified Society of Radiologists in Ultrasound criteria with a higher peak systolic velocity threshold of 180 cm/s for 50% to 69% ICA stenosis. Additional emerging techniques, including 3D imaging, contrast-enhanced ultrasound, and superb microvascular imaging, may help identify vulnerable plaque and thus help further risk-stratify patients in the future.

Randomized Controlled Trial of Cilostazol Addition for In-Stent Restenosis After Carotid Artery Stenting

BACKGROUND

Restenosis after carotid artery stenting (CAS) is associated with the risk of developing ischemic stroke. We aimed to evaluate the inhibitory effect of cilostazol addition on in-stent restenosis (ISR) in patients treated with CAS.

METHODS

In a randomized, open-label, blind-end point trial, patients with symptomatic and asymptomatic carotid artery stenosis and scheduled for CAS were randomly assigned to adding cilostazol (50 or 100 mg, twice per day) on other antiplatelets from 3 days before CAS or not adding cilostazol. Concomitant use of other antiplatelets was unrestricted. ISR was diagnosed by a peak systolic velocity of at least 1.75 m/s on duplex ultrasonography. The primary outcome was incidence of ISR within 2 years after CAS. Secondary outcomes included occurrences of cardiovascular events or any death and hemorrhagic events.

RESULTS

Participants were recruited from December 2010 to September 2015. Although the sample size was initially set to be 900 (450 in each group), 631 patients (mean age 69.9 years, 558 men, 325 in the cilostazol, and 306 in the noncilostazol group) were included in the primary analysis. Within 2 years' follow-up, ISR occurred in 31 of 325 patients (cumulative incidence 10.8%) in the cilostazol group and 46 of 306 patients (19.6%) in the noncilostazol group (hazard ratio, 0.64 [95% CI, 0.41-1.0]; P=0.056). In the exploratory analysis, incidence of ISR beyond 30 days after CAS was lower in the cilostazol group than in the noncilostazol group (10.3% versus 19.3%; P=0.040). Incidences of cardiovascular events or any death and hemorrhagic events were similar between the groups (6.2% versus 6.7% and 2.3% versus 1.4%, respectively).

CONCLUSIONS

The addition of cilostazol to other antiplatelet agents could contribute to the reduction of ISR in the chronic stage of patients who underwent CAS, the authenticity of which depends on further studies with sufficient statistical power.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01261234.

Biomechanical analysis of nickel-titanium (NiTi)-cobalt-chromium (CoCr) hybrid-braided dense-mesh stents for carotid artery stenosis

This study investigates NiTi-CoCr hybrid carotid artery stents to enhance mechanical properties over NiTi-only designs. Different configurations (24NiTi, 20NiTi-4CoCr, 16NiTi-8CoCr, and 12NiTi-12CoCr) were evaluated through radial compression and bending simulations. The 12NiTi-12CoCr stent showed the highest radial support (39.37 N) and increased bending strength by 77.96%. When modeled in a stenotic artery, this stent reduced stenosis from 81.52% to 29.33% and improved blood flow dynamics, alleviating high-pressure zones and balancing wall shear stress. These results suggest that CoCr wires improve stent performance, with the 12NiTi-12CoCr stent offering significant biomechanical and hemodynamic benefits.

Carotid Artery Geometry Modifications and Clinical Implications after Carotid Artery Stenting

BACKGROUND

Carotid artery stenting (CAS) could lead to a modification of the carotid bifurcation geometry with possible clinical implications. This study aimed to clarify the geometrical impact of three carotid stents with different designs on the carotid bifurcation and its clinical consequences.

METHODS

This was a retrospective single-center study. We included all patients who underwent CAS in a 3-year period. Anatomical changes of the carotid bifurcation were evaluated by reviewing angiographic images. The population was divided into three groups based on the stent implanted: Group 1 (Carotid Wallstent), Group 2 (Roadsaver), and Group 3 (C-Guard).

RESULTS

A total of 226 patients were included. The mean age was 77.0 ± 7.4 years and 72.5% (164/226) were male. Three different stents were implanted into three groups: Group 1 (n = 131/226, 58%), Group 2 (n = 57/226, 25.2%), and Group 3 (n = 38/226, 16.8%). The mean pre-stent implantation CCA-ICA angle of the entire population was 155 ± 14.9°, and the post-CAS angle was 167.7 ± 8.7° (p = 0.0001). In every subgroup, the difference was statistically different, with the biggest difference registered in Group 2 (-16.1 ± 13.2°). Regarding stent oversizing, there was a significant relationship between CCA oversizing and CCA-ICA angle modification (p = 0.006). During follow-up, a total of 14 (6.2%) restenoses were registered. The mean CCA-ICA angle modification in the restenosis group was -9.5 ± 14.4° vs. -12.8 ± 11.9° in the no-restenosis group with no significant statistical differences were outlined (p = 0.3).

CONCLUSIONS

Compared to the Carotid Wallstent and C-Guard, the Roadsaver stent appears to have a lower adaptability to the carotid vascular territory, resulting in a higher CCA-ICA angle modification after implantation, with no impact on the stent restenosis rate.

Influence of Bridging Stent Graft Implantation into the Renal Artery during Complex Endovascular Aortic Procedures on the Renal Resistance Index

Comparative sonographic examination of the renal resistance index (RRI) can provide evidence of renal artery stenosis. The extent to which the RRI is changed after stent graft implantation is not known. The aim of this study was to investigate the influence of stent graft implantation into non-diseased renal arteries during endovascular treatment of pararenal aortic aneurysms on the RRI. Sonographic examinations of the kidneys were conducted using a GE ultrasound system. The evaluation was performed according to the European Society for Vascular Surgery (ESVS) 2D standard criteria. RRI values were determined in consecutive patients on the day before and after stent graft implantation and compared for each kidney. A total of 32 consecutive patients (73.9 ± 8.2 years, 5 females, 27 males) were treated with a fenestrated or branched aortic stent graft including bridging stent graft implantations into both renal arteries and received pre- and postinterventional examinations. Sonomorphologically, the examined kidneys were inconspicuous. The arborisation of the renal perfusion was preserved pre- and post-implantation. The RRI did not differ (0.66 ± 0.06 versus 0.67 ± 0.07; p = ns). Successful stent graft implantation into non-stenosed renal arteries did not lead to a relevant change in RRI. Therefore, the RRI is a suitable tool for assessing renal perfusion after fenestrated or branched endovascular aortic therapy.

Role of carotid duplex in the assessment of carotid artery restenosis after endarterectomy or stenting

Introduction

Redo carotid endarterectomy (CEA) and carotid stenting (CAS) are often performed when there is evidence of post-procedural restenosis. The incidence of restenosis after carotid reconstruction is not negligible, ranging from 5 to 33%. The diagnosis of significant internal carotid artery (ICA) restenosis is usually based on duplex ultrasound (US) criteria, mostly on peak-systolic flow velocity (PSV). However, there have been no generally accepted duplex US criteria for carotid restenosis after CAS or CEA.

Methods

In this systematic review, the PubMed/ Medline and Scopus databases were screened to find trials that reported duplex US criteria for significant restenosis after CEA and/or CAS. Only those reports were analyzed in which the restenoses were also assessed by CT/MR or digital subtraction angiography as comparators for duplex US.

Results

Fourteen studies met the predetermined search criteria and were included in this review. In most studies, PSV thresholds for significant in-stent ICA restenosis after CAS were higher than those for significant stenosis in non-procedurally treated (native) ICA. Many fewer studies investigated the US criteria for ICA restenosis after CEA. Despite the heterogeneous data, there is a consensus to use higher flow velocity thresholds for assessment of stenosis in stented ICA than in native ICA; however, there have been insufficient data about the flow velocity criteria for significant restenosis after CEA. Although the flow velocity thresholds for restenosis after CAS and CEA seem to be different, the large studies used the same duplex criteria to define restenosis after the two procedures. Moreover, different studies used different flow velocity thresholds to define ICA restenosis, leading to variable restenosis rates.

Discussion

We conclude that (1) further examinations are warranted to determine appropriate duplex US criteria for restenosis after CAS and CEA, (2) single duplex US parameter cannot be used to reliably determine the degree of ICA restenosis, (3) inappropriate US criteria used in large studies may have led to false restenosis rates, and (4) studies are required to determine if there is a benefit from redo carotid artery procedure, such as redo-CEA or redo-CAS, starting with prospective risk stratification studies using current best practice non-invasive care alone.

Comparison of carotid endarterectomy and repeated carotid angioplasty and stenting for in-stent restenosis (CERCAS trial): a randomised study

BACKGROUND AND AIM

In-stent restenosis (ISR) belongs to an infrequent but potentially serious complication after carotid angioplasty and stenting in patients with severe carotid stenosis. Some of these patients might be contraindicated to repeat percutaneous transluminal angioplasty with or without stenting (rePTA/S). The purpose of the study is to compare the safety and effectiveness of carotid endarterectomy with stent removal (CEASR) and rePTA/S in patients with carotid ISR.

METHODS

Consecutive patients with carotid ISR (≥80%) were randomly allocated to the CEASR or rePTA/S group. The incidence of restenosis after intervention, stroke, transient ischaemic attack myocardial infarction and death 30 days and 1 year after intervention and restenosis 1 year after intervention between patients in CEASR and rePTA/S groups were statistically evaluated.

RESULTS

A total of 31 patients were included in the study; 14 patients (9 males; mean age 66.3±6.6 years) were allocated to CEASR and 17 patients (10 males; mean age 68.8±5.6 years) to the rePTA/S group. The implanted stent in carotid restenosis was successfully removed in all patients in the CEASR group. No clinical vascular event was recorded periproceduraly, 30 days and 1 year after intervention in both groups. Only one patient in the CEASR group had asymptomatic occlusion of the intervened carotid artery within 30 days and one patient died in the rePTA/S group within 1 year after intervention. Restenosis after intervention was significantly greater in the rePTA/S group (mean 20.9%) than in the CEASR group (mean 0%, p=0.04), but all stenoses were <50%. Incidence of 1-year restenosis that was ≥70% did not differ between the rePTA/S and CEASR groups (4 vs 1 patient; p=0.233).

CONCLUSION

CEASR seems to be effective and save procedures for patients with carotid ISR and might be considered as a treatment option.

TRIAL REGISTRATION NUMBER

NCT05390983.

Radial and ulnar approach for carotid artery stenting with Roadsaver™ double layer micromesh stent: Early and long-term follow-up

AIMS

We aimed to evaluate the feasibility and safety of carotid artery stenting (CAS) with a newly designed double-layer micromesh stent using wrist approach in patients with significant carotid disease.

MATERIALS AND METHODS

Between January 2016 and December 2021, 105 patients undergoing CAS with Roadsaver™ stent were enrolled in a single center prospective study. Follow-up assessments included neurological exams, duplex ultrasound (DUS), and 12-lead ECG. The primary endpoint was the 30-day composite rate of stroke, death, and myocardial infarction. Secondary endpoints included procedure success, access site complications, device success, target lesion revascularization, and in-stent restenosis evaluated with DUS. Long-term outcomes up to 72 months of follow-up were assessed in all eligible patients.

RESULTS

The study population was predominantly male (69.5%) with a median age of 68 ± 8 years. Patients were symptomatic in 80% of the cases, and 35% fulfilled the high-risk criteria for surgical endarterectomy. The right internal carotid artery was the target artery in 56 (53.4%), and the left in 49 (46.6%) of the cases. All procedures were successfully completed from the right wrist, with right radial access in 94 (89.5%) cases and ulnar artery access with previous radial artery occlusion in 11 (10.5%) cases. All patients were treated successfully with the study device. The primary endpoint was met with a 30-day major adverse event rate of 0.9% (1/105). Up to 72 months of follow-up (median 30 ± 20 months) there were no strokes, neurological deaths, or target lesion revascularization of the treated lesion. Doppler ultrasound examination revealed nonsignificant in-stent restenosis in two asymptomatic patients. There was no hand ischemia detected in any patient.

CONCLUSION

Results from this study demonstrate the radial and ulnar access for CAS with double layer micromesh Roadsaver™ stent is safe and feasible and associated with favorable early and long-term follow-up.

Ultrasound diagnosis of carotid artery stenosis and occlusion

Carotid artery ultrasonography is capable of diagnosing or inferring the presence or absence of stenosis or occlusion of the internal carotid artery (ICA) and vertebral artery (VA), as well as the not directly observable distal ICA, middle cerebral artery (MCA), and basilar artery (BA). Stenosis at the origin of the ICA is mainly evaluated using the parameter peak systolic velocity (PSV), with values of ≥ 200-230 cm/s indicating severe stenosis. Recently, the acceleration time ratio has been reported for diagnosis of ICA origin stenosis. An indicator called the end-diastolic (ED) ratio can be used for diagnosing occlusion of the distal ICA or the M1 segment of the MCA. The PSV of stenosis can be used to diagnose stenosis at the beginning of the VA or V1, and mean flow velocity, mean ratio, and diameter ratio can be used to diagnose distal VA occlusion. Furthermore, the usefulness of the VA pulsatility index and resistance index has been suggested for diagnosing stenosis or occlusion of the BA. This review outlines diagnostic sonography criteria for stenosis and occlusion of extracranial and intracranial arteries.

Late Outcomes of Carotid Artery Stenting for Radiation Therapy-Induced Carotid Stenosis

PURPOSE

Carotid artery stenting (CAS) appears as a promising alternative treatment to carotid endarterectomy for radiation therapy (RT)-induced carotid stenosis. However, this is based on a poor level of evidence studies (small sample size, primarily single institution reports, few long-term data). The purpose of this study was to report the long-term outcomes of a multicentric series of CAS for RT-induced stenosis.

METHODS

All CAS for RT-induced stenosis performed in 11 French academic institutions from 2005 to 2017 were collected in this retrospective study. Patient demographics, clinical risk factors, elapsed time from RT, clinical presentation and imaging parameters of carotid stenosis were preoperatively gathered. Long-term outcomes were determined by clinical follow-up and duplex ultrasound. The primary endpoint was the occurrence of cerebrovascular events during follow-up. Secondary endpoints included perioperative morbidity and mortality rate, long-term mortality rate, primary patency, and target lesion revascularization.

RESULTS

One hundred and twenty-one CAS procedures were performed in 112 patients. The mean interval between irradiation and CAS was 15 ± 12 years. In 31.4% of cases, the lesion was symptomatic. Mean follow-up was 42.5 ± 32.6 months (range 1-141 months). The mortality rate at 5 years was 23%. The neurologic event-free survival and the in-stent restenosis rates at 5 years were 87.8% and 38.9%, respectively. Diabetes mellitus (p=0.02) and single postoperative antiplatelet therapy (p=0.001) were found to be significant predictors of in-stent restenosis. Freedom from target lesion revascularization was 91.9% at 5 years.

CONCLUSION

This study showed that CAS is an effective option for RT-induced stenosis in patients not favorable to carotid endarterectomy. The CAS was associated with a low rate of neurological events and reinterventions at long-term follow-up.

Diabetes Mellitus and Clinical Outcomes in Carotid Artery Revascularization Using Second-Generation, MicroNet-Covered Stents: Analysis from the PARADIGM Study

INTRODUCTION

Carotid artery stenting (CAS) using conventional (single-layer) stents is associated with worse clinical outcomes in diabetes mellitus (DM) vs. non-DM patients: an effect driven largely by lesion-related adverse events. CAS outcomes with MicroNet-covered stents (MCS) in diabetic patients have not been evaluated.

AIM

To compare short- and long-term clinical outcomes and restenosis rate in DM vs. non-DM patients with carotid stenosis treated using MCS.

MATERIALS AND METHODS

In a prospective study in all-comer symptomatic and increased-stroke-risk asymptomatic carotid stenosis, 101 consecutive patients (age 51-86 years, 41% diabetics) underwent 106 MCS-CAS. Clinical outcomes and duplex ultrasound velocities were assessed periprocedurally and at 30 days/12 months.

RESULTS

Baseline characteristics of DM vs. non-DM patients were similar except for a higher prevalence of recent cerebral symptoms in DM. Type 1 and type 1+2 plaques were more prevalent in DM patients (26.7% vs. 9.8%, p = 0.02; 62.2% vs. 37.7%, p = 0.01). Proximal embolic protection was more prevalent in DM (60% vs. 36%; p = 0.015). 30-day clinical complications were limited to a single periprocedural minor stroke in DM (2.4% vs. 0%, p = 0.22). 12-month in-stent velocities and clinical outcomes were not different (death rate 4.8% vs. 3.3%; p = 0.69; no new strokes). Restenosis rate was not different (0% vs. 1.7%, p = 0.22).

CONCLUSIONS

MCS may offset the adverse impact of DM on periprocedural, 30-day, and 12-month clinical complications of CAS and minimize the risk of in-stent restenosis. In this increased-stroke-risk cohort, adverse event rate was low both in DM and non-DM. Further larger-scale clinical datasets including extended follow-ups are warranted.

Early and Long-Term Outcomes of Carotid Stenting and Carotid Endarterectomy in Women

Background: The role of carotid revascularization in women remains intensely debated because of the lower benefit and higher perioperative risks concerning the male counterpart. Carotid artery endarterectomy (CEA) and stenting (CAS) represent the two most valuable stroke prevention techniques due to large vessel disease. This study investigates the early and late outcomes in female sex in a real-world everyday clinical practice. Methods: Data were retrospectively analyzed from a single-center database prospectively compiled. A total of 234 procedures, both symptomatic and asymptomatic, were identified (98 CEAs and 136 CASs). Perioperative risks of death, cerebral ischemic events, and local complications were analyzed and compared between the two groups. Long-term outcomes were evaluated in overall survival, freedom from ipsilateral stroke/transient ischemic attack, and freedom from restenosis (>50%) and reintervention. Results: Women who underwent CAS and CEA did not differ in perioperative ischemic cerebral events (2.2 vs. 0%, p = 0.26) and death (0.8 vs. 0%, p = 1). Other perioperative and 30-day outcomes were similarly distributed within the two groups. Kaplan-Meier curves between CAS and CEA groups highlighted no statistical differences at 6 years in overall survival (77.4 vs. 77.1%, p = 0.47) of ipsilateral stroke/transient ischemic attack (94.1 vs. 92.9%, p = 0.9). Conversely, significant differences were showed in 6 years freedom from restenosis (93.1 vs. 83.3%, p = 0.03) and reinterventions (97.7 vs. 87.8%, p = 0.015). Conclusion: Our results revealed that both CEA and CAS have acceptable perioperative risk in women. Long-term outcomes highlighted favorable indications for both procedures, especially for CAS, which seemed to be an excellent alternative to CEA in female patients when performed by well-trained operators.

Defining Duplex Ultrasound Criteria for In-Stent Restenosis of the Superior Mesenteric Artery

BACKGROUND

This study sought to define duplex ultrasound (DUS) velocity criteria predicting ≥70% stenosis in superior mesenteric artery (SMA) stents by correlating in-stent peak systolic velocity (PSV) with computed tomographic angiography (CTA) measurements of percent stenosis.

METHODS

A retrospective review of 109 patients undergoing SMA stenting between 2003 and 2018 was conducted at a single institution. Thirty-seven surveillance duplex ultrasound studies were found to have a CTA performed within 30 days of study completion. Bare metal (n = 20) and covered stents (n = 17) were included. Velocities were paired to in-stent restenosis (ISR) measured by mean vessel diameter reduction on SMA centerline reconstructions from CTA. Receiver operating characteristic (ROC) curves was generated and logistic regression models for ≥70% ISR probability were used to define velocity criteria in the stented SMA.

RESULTS

At a PSV of 300 cm/sec, the sensitivity is 100% and specificity 80% for a ≥70% in-stent SMA stenosis. At a PSV of 400 cm/sec, the sensitivity and positive predictive value (PPV) is 63% and the specificity and negative predictive value (NPV) is 90%. A PSV of 450 cm/sec was consistent with the highest specificity (100%) and PPV (100%) but lower sensitivity (50%) and NPV (87.9%). One patient with a PSV of 441 cm/sec on surveillance DUS died from complications of acute-on-chronic mesenteric ischemia.

CONCLUSIONS

A PSV of 400 cm/sec on mesenteric DUS can predict ≥70% ISR with high sensitivity and should be considered as a diagnostic threshold for SMA in-stent restenosis.

The management of carotid restenosis: a comprehensive review

Carotid artery stenosis (CS) is a major medical problem affecting approximately 10% of the general population 80 years or older and causes stroke in approximately 10% of all ischemic events. In patients with symptomatic, moderate-to-severe CS, carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS), has been used to lower the risk of stroke. In primary CS, CEA was found to be superior to best medical therapy (BMT) according to 3 large randomized controlled trials (RCT). Following CEA and CAS, restenosis remains an unsolved problem involving a large number of patients as the current treatment recommendations are not as clear as those for primary stenosis. Several studies have evaluated the risk of restenosis, reporting an incidence ranging from 5% to 22% after CEA and an in-stent restenosis (ISR) rate ranging from 2.7% to 33%. Treatment and optimal management of this disease process, however, is a matter of ongoing debate, and, given the dearth of level 1evidence for the management of these conditions, the relevant guidelines lack clarity. Moreover, the incidence rates of stroke and complications in patients with carotid stenosis are derived from studies that did not use contemporary techniques and materials. Rapidly changing guidelines, updated techniques, and materials, and modern medical treatments make actual incidence rates barely comparable to previous ones. For these reasons, RCTs are critical for determining whether these patients should be treated with more aggressive treatments additional to BMT and identifying those patients indicated for surgical or endovascular treatments. This review summarizes the current evidence and controversies concerning the risks, causes, current treatment options, and prognoses in patients with restenosis after CEA or CAS.

Usefulness of Carotid Ultrasonography for Risk Stratification of Cerebral and Cardiovascular Disease

Carotid ultrasonography is useful for the assessments of the risk stratification for stroke or coronary artery disease, because it is a simple, repeatable, and noninvasive procedure. The carotid intima-media thickness (IMT), which is assessed using carotid ultrasonography, is a widely used surrogate marker for the severity of atherosclerosis. Several large clinical studies showed that increased carotid IMT is associated with the future stroke or cardiovascular events. In addition, in many clinical trials, it has been adopted for surrogate markers of clinical endpoints of medical intervention. Moreover, carotid ultrasonography allows the measurement of the presence and characteristics of plaques and the severity of carotid artery stenosis. The unstable morphology of plaque, such as hypoechoic, ulcer, and mobility, is associated with future ischemic stroke events. The screening tool of asymptomatic carotid artery stenosis is also important, although whether routine carotid ultrasonography assessment is recommended in the general population remains controversial. The screening of carotid artery stenosis using ultrasonography is essential for not only daily clinical settings but also management of patients with acute ischemic stroke. The patients with atherothrombotic stroke with severe internal carotid artery stenosis should be considered to surgical intervention, and duplex ultrasound approach is important to estimate for the severity of carotid stenosis. Physicians should keep in mind the usefulness of carotid ultrasonography for risk stratification of cerebral and cardiovascular disease based on various aspects. In addition, visual assessment or dynamic changes using carotid ultrasonography could provide the various and valuable insights in clinical settings.

Follow-up after carotid stenting with the CASPER stent system: A duplex ultrasound evaluation

OBJECTIVE

To report results of duplex ultrasound evaluation of consecutive patients after carotid stenting with the double layer Carotid Artery Stent designed to Prevent Embolic Release (CASPER) stent system.

METHODS

Between January 2014 and June 2017, a single-center, retrospective study of 101 consecutive patients (21.8% female; median age, 72.1 years) was performed. Patients with internal carotid artery stenosis treated with the CASPER stent were included. Eligibility criteria for stenting included stenosis of ≥70% of the vessel diameter (or ≥50% diameter with ulceration) in symptomatic carotid artery stenosis or ≥80% stenosis in asymptomatic patients at the carotid artery bifurcation or the proximal cervical internal carotid artery. Duplex ultrasound examination was performed before and within 24 hours of implantation as well as at 14 days, and 3, 6, and 12 months.

RESULTS

At the 12-month follow-up visit, moderate in-stent restenosis (ISR) (≥50% and <70%) was detected in three stents (2.8%) and severe (≥70%) ISR in two (1.9%; including one case of stent occlusion). All but the two latter patients remained asymptomatic during the follow-up period. One patient required retreatment for ISR after a minor stroke and another patient with stent occlusion also re-presented with a minor stroke. Multivariable logistic regression was unable to detect any significant factors associated with ISR.

CONCLUSIONS

Duplex ultrasound examination after carotid stenting is a useful tool for patient follow-up and determination of ISR. We found a low incidence of ISR assessed by duplex ultrasound examination at 12 months after CASPER stenting, but further studies are warranted.

Comparison of Carotid Endarterectomy and Stenting for Symptomatic Internal Carotid Artery Near-Occlusion

BACKGROUND AND PURPOSE

Carotid near-occlusion is defined as severe stenosis of the internal carotid artery with partial or full collapse of the distal vessel wall. The major studies evaluating carotid revascularization excluded patients with carotid near-occlusion. Given the paucity of data in the literature, we attempted to evaluate the safety of carotid endarterectomy and carotid artery stenting in carotid near-occlusion.

MATERIALS AND METHODS

A retrospective data base review was performed from January 2010 to December 2018 to identify patients who underwent carotid endarterectomy or carotid artery stenting for symptomatic ICA near-occlusion and had 1-month clinical and imaging follow-up with carotid sonography. The medical records and imaging studies of patients with ICA near-occlusion were selected for analysis.

RESULTS

Forty-five patients met the criteria for ICA near-occlusion, of whom 39 were included in the study, given insufficient 1-month follow-up on 6 patients. Of the 39 patients, 25 underwent carotid endarterectomy and 14 underwent carotid artery stenting. All patients had technically successful immediate revascularization of the ICA. Most (33 of 39) had 1-year follow-up postoperatively. Patients with carotid artery stenting had 20% restenosis and 79% vessel maturation rates, while patients with carotid endarterectomy had 17.4% restenosis and 84% vessel maturation. There was no significant difference in periprocedural complication rates between the 2 procedures.

CONCLUSIONS

Carotid artery stenting shows similar outcomes in restenosis and vessel maturation rates compared with carotid endarterectomy for ICA near-occlusion. There were no major differences between the 2 treatments in clinical outcomes or periprocedural complications. Carotid artery stenting is a revascularization option for carotid near-occlusion if the patient is considered at high risk for carotid endarterectomy.

Carotid Ultrasound

Doppler ultrasound (US) is the primary noninvasive imaging modality for detecting, grading, and monitoring extracranial internal carotid artery (ICA) stenosis, which is a well-established surrogate marker for stroke risk. In addition, Doppler US is the primary imaging modality for surveillance of patients following carotid intervention with endarterectomy or stent placement. This article reviews the pathophysiology and epidemiology of stroke, technique for performing a carotid US examination, normal findings, and diagnostic US criteria for evaluating carotid plaque, grading stenosis in the native ICA and following intervention, as well as waveform analysis of the carotid arteries.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Carotid Artery Stent Placement and Carotid Endarterectomy: A Challenge for Urgent Treatment after Stroke-Early and 12-Month Outcomes in a Comprehensive Stroke Center

PURPOSE

To compare feasibility, 12-month outcome, and periprocedural and postprocedural risks between carotid artery stent (CAS) placement and carotid endarterectomy (CEA) performed within 1 week after transient ischemic attack (TIA) or mild to severe stroke onset in a single comprehensive stroke center.

MATERIALS AND METHODS

Retrospective analysis of prospective data collected from 1,148 patients with ischemic stroke admitted to a single stroke unit between January 2013 and July 2015 was conducted. Among 130 consecutive patients with symptomatic carotid stenosis, 110 (10 with TIA, 100 with stroke) with a National Institutes of Health Stroke Scale (NIHSS) score < 20 and a prestroke modified Rankin Scale (mRS) score < 2 were eligible for CAS placement or CEA and treated according to the preference of the patient or a surrogate. Periprocedural (< 48 h) and postprocedural complications, functional outcome, stroke, and death rate up to 12 months were analyzed.

RESULTS

Sixty-two patients were treated with CAS placement and 48 were treated with CEA. Several patients presented with moderate or major stroke (45.8% CEA, 64.5% CAS). NIHSS scores indicated slightly greater severity at onset in patients treated with a CAS vs CEA (6.6 ± 5.7 vs 4.2 ± 3.4; P = .08). Complication rates were similar between groups. mRS scores showed a significant improvement over time and a significant interaction with age in both groups. Similar incidences of death or stroke were shown on survival analysis. A subanalysis in patients with NIHSS scores ≥ 4 showed no differences in complication rate and outcome.

CONCLUSIONS

CAS placement and CEA seem to offer early safe and feasible secondary stroke prevention treatments in experienced centers, even after major atherosclerotic stroke.

Sonographic Evaluation of Complications of Extracranial Carotid Artery Interventions

Carotid endarterectomy and carotid artery stenting are among the most common peripheral vascular procedures performed worldwide. Sonography is the initial and often only imaging modality used in the evaluation of iatrogenic carotid arterial injuries. This pictorial essay provides an overview of the clinical and sonographic findings of complications after interventions in the extracranial carotid arteries, including dissection, fluid collections, pseudoaneurysm, thrombosis, thromboembolism, restenosis, and stent deformation. Grayscale, color, and pulsed Doppler imaging findings are reviewed, and correlations with computed tomography, magnetic resonance imaging, and angiography are provided.

Restenosis after carotid artery stenting

As a common etiology for ischemic stroke, atherosclerotic carotid stenosis has been targeted by vascular surgery since 1950s. Compared with carotid endarterectomy, carotid angioplasty and stenting (CAS) is almost similarly efficacious and less invasive. These advantages make CAS an alternative in treating carotid stenosis. However, accumulative evidences suggested that the long-term benefit-risk ratio of CAS may be decreased or even neutralized by the complications related to in-stent restenosis (ISR). Therefore, investigating the mechanisms and identifying the influential factors of ISR are of vital importance for improving the long-term outcomes of CAS. As responses to intrinsic and extrinsic injuries, intimal hyperplasia and vascular smooth muscle cell proliferation have been regarded as the principle mechanisms for ISR development. Due to the lack of consensus-based definition and consistent follow-up protocol, the reported incidences of ISR after CAS varied widely among studies. These variations made the inter-study comparisons of ISR largely illogical. To eliminate restenosis after CAS, both surgery and endovascular procedures have been attempted with promising results. For preventing ISR, drug-eluting stents and antiplatelets have been proposed as potential solutions.

Incidence of New Ischaemic Brain Lesions After Carotid Artery Stenting with the Micromesh Roadsaver Carotid Artery Stent: A Prospective Single-Centre Study

AIMS

Several randomized trials of patients with carotid stenosis show increased adverse neurological events with stenting versus endarterectomy in the 30-day post-procedure. This study examines the incidence of new ischaemic lesions in patients treated in our centre using the new Roadsaver stent.

METHODS AND RESULTS

Between September 2015 and January 2016, 23 consecutive patients (age 74.3 ± 7.3 years, 17.4 % female) underwent carotid artery stenting with the Roadsaver stent, a nitinol double-layer micromesh device. A distal protection device was used in all cases. Diffusion-weighted magnetic resonance imaging was performed 24 h before, and 24 h and 30 days after the procedure. The 24-h post-procedure imaging showed 15 new ipsilateral ischaemic lesions in 7 (30.4 %) patients: median volume 0.076 cm³ (interquartile range 0.065-0.146 cm³). All lesions were asymptomatic. The 30-day imaging showed complete resolution of all lesions and no new ischaemic lesions. Follow-up clinical and ultrasound examinations at 30 days and 6 months recorded no adverse cardiac or cerebrovascular events.

CONCLUSIONS

Protected stenting with micromesh Roadsaver stent showed good safety and efficacy in the treatment of carotid stenosis, with a low incidence of delayed embolic events and new ipsilateral ischaemic brain lesions. These preliminary results are encouraging, but need to be confirmed with larger populations.

In-Stent Restenosis After Carotid Artery Stenting: From Diagnosis to Treatment

Although carotid artery stenting is a safe and effective treatment for preventing ischaemic stroke in significant carotid atherosclerotic disease, it can be complicated by in-stent restenosis (ISR). Factors involved in the ISR process are both mechanical and patient-related, but the most important is the neointimal thickening within stent struts, leading to lumen reduction. Overall incidence of carotid ISR is low and related embolic risk seems to be lower than native disease. Digital subtraction angiography is the gold standard for diagnosis. Nowadays, Doppler ultrasound should be considered the first-line investigation, due to its non-invasiveness and reproducibility. Computed tomography angiography remains useful when Doppler ultrasound is inconclusive. Indication and modality of treatment of ISR are still debated: both surgery (carotid endarterectomy with stent removal in most cases) or interventional procedures such as percutaneous transluminal angioplasty with simple balloon, cutting-balloon, drug-eluting balloon, and stenting, showed safety and efficacy in follow-up. Surgery is currently reserved for selected cases. Carotid ISR is an overall rare complication which can be easily identified at routine follow-up. This paper is a literature review and state-of-the-art assessment of ISR, clinical features, diagnosis, and treatment.

Prognostic Factors for Neurologic Outcome in Patients with Carotid Artery Stenting

BACKGROUND

Carotid artery stenting (CAS) is a valid treatment for patients with carotid artery stenosis. The long-term outcome and prognostic factors in Asian population after CAS are not clear. This study aimed to identify the prognostic factors among Asian patients who have undergone CAS.

METHODS

We retrospectively analyzed 246 patients with CAS. Annual carotid duplex ultrasound was used to identify restenosis. Peri-procedural complications, restenosis, neurologic outcomes, and mortality were recorded. Cox regression analyses were used to identify prognostic factors.

RESULTS

The mean follow-up time was 49.2 months. Procedural success was achieved in 237 patients (98.3%), and protection devices were used in 208 patients (84.5%). Within 30 days of CAS, 13 (4.3% per procedure) peri-procedural complications occurred. During the follow-up period, 24 (9.7%) patients developed restenosis, and 37 (15.0%) developed ischemic strokes. In a multiple logistic regression analysis, head and neck radiotherapy [hazard ratio (HR) = 9.9, 95% confidence interval (CI), 3.38-29.1, p < .001], stent diameter (HR = 0.72, 95% CI, 0.58-0.89, p = .003), and predilatation (HR = 3.08 95% CI, 1.21-7.81, p = .018) were independent predictors for restenosis. In Cox regression analysis, hypercholesterolemia (HR = 0.25, 95% CI, 0.07-0.94, p = .04), head and neck radiotherapy (HR = 6.2, 95% CI, 1.8-21.3, p = .004), and restenosis (HR = 3.6, 95% CI, 1.1-11.18, p = .04) were predictors for recurrent ipsilateral ischemic stroke.

CONCLUSIONS

CAS provides reliable long-term results in Asian patients with carotid stenosis. Restenosis is associated with an increased rate of recurrent stroke and should be monitored carefully following CAS.

KEY WORDS

Carotid artery disease • Prognosis • Cerebrovascular disease.

Neurosonology and noninvasive imaging of the carotid arteries

In this chapter, we review imaging of the extracranial carotid arteries and the indications for noninvasive carotid artery evaluation, measuring the degree of arterial stenosis and plaque morphology. We also analyze the types of noninvasive imaging, including carotid duplex ultrasound, transcranial Doppler, magnetic resonance angiography, and computer tomography angiography. We look at each of these modalities, briefly discussing techniques, benefits, limitations, and sources of error. Furthermore, we discuss the apparent accuracy and the need for multimodality imaging. Finally, an imaging algorithm for the evaluation of the extracranial carotid arteries is proposed, which is in routine use at our hospital.

Drug-coated balloon dilation before carotid artery stenting of post-carotid endarterectomy restenosis

PURPOSE

To investigate if drug-coated balloon (DCB) predilation may improve the efficacy of carotid artery stenting (CAS) for restenosis after carotid endarterectomy (CEA).

METHODS

Eighteen consecutive patients (11 men; median age 75 years) with significant restenosis within 24 months of CEA were treated with a paclitaxel-coated DCB prior to CAS. Clinical outcomes and stent patency were systematically appraised.

RESULTS

All patients were successfully treated according to this clinical protocol. The only complication occurred in a patient who had a transient ischemic attack during prolonged DCB inflation. At a median follow-up of 18 months, no >50% restenosis was observed on duplex ultrasound scans; however, moderate hyperplasia at the proximal stent edge was found in 4 patients. One patient died at 9 months from a myocardial infarction.

CONCLUSION

Despite the small sample size and in keeping with the historically high risk of recurrent restenosis after CAS for CEA restenosis, this case series suggests that DCB dilation followed by CAS for postsurgical restenosis is feasible, safe, and may be associated with favorable clinical outcomes at midterm follow-up.

Long-term follow-up study of endarterectomy versus angioplasty in patients with symptomatic severe carotid stenosis trial

BACKGROUND AND PURPOSE

We aimed at comparing the long-term benefit-risk balance of carotid stenting versus endarterectomy for symptomatic carotid stenosis.

METHODS

Long-term follow-up study of patients included in Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis (EVA-3S), a randomized, controlled trial of carotid stenting versus endarterectomy in 527 patients with recently symptomatic severe carotid stenosis, conducted in 30 centers in France. The main end point was a composite of any ipsilateral stroke after randomization or any procedural stroke or death.

RESULTS

During a median follow-up of 7.1 years (interquartile range, 5.1-8.8 years; maximum 12.4 years), the primary end point occurred in 30 patients in the stenting group compared with 18 patients in the endarterectomy group. Cumulative probabilities of this outcome were 11.0% (95% confidence interval, 7.9-15.2) versus 6.3% (4.0-9.8) in the endarterectomy group at the 5-year follow-up (hazard ratio, 1.85; 1.00-3.40; P=0.04) and 11.5% (8.2-15.9) versus 7.6% (4.9-11.8; hazard ratio, 1.70; 0.95-3.06; P=0.07) at the 10-year follow-up. No difference was observed between treatment groups in the rates of ipsilateral stroke beyond the procedural period, severe carotid restenosis (≥70%) or occlusion, death, myocardial infarction, and revascularization procedures.

CONCLUSIONS

The long-term benefit-risk balance of carotid stenting versus endarterectomy for symptomatic carotid stenosis favored endarterectomy, a difference driven by a lower risk of procedural stroke after endarterectomy. Both techniques were associated with low and similar long-term risks of recurrent ipsilateral stroke beyond the procedural period.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00190398.

Carotid artery stenting has increased risk of external carotid artery occlusion compared with carotid endarterectomy

OBJECTIVE

The external carotid artery (ECA) can be an important source of cerebral blood flow in cases of high-grade internal carotid artery stenosis or occlusion. However, the treatment of the ECA is fundamentally different between carotid endarterectomy (CEA) and carotid artery stenting (CAS). CEA is routinely associated with endarterectomy of the ECA, whereas CAS excludes the ECA from direct flow. We hypothesize that these differences make ECA occlusion more common after CAS. Further, the impact of CAS on blood flow into the ECA is interesting because the flow from the stent into the ECA is altered in a way that may promote local inflammation and may influence in-stent restenosis (ISR). Thus, our objective was to use our institutional database to identify whether CAS increased the rate of ECA occlusion and, if it did, whether ECA occlusion was associated with ISR.

METHODS

Patients undergoing CAS or CEA from February 2007 to February 2012 were identified from our institutional carotid therapy database. Preoperative and postoperative images of patients who followed up in our institution were included in the analysis of ECA occlusion and rates of ISR.

RESULTS

There were 210 (67%) CAS patients and 207 (60%) CEA patients included in this analysis. Despite CAS patients being younger (68 vs 70 years), having shorter follow-up (12.5 vs 56.2 months), and being more likely to take clopidogrel (97% vs 35%), they had an increased rate of ECA occlusion (3.8%) compared with CEA patients (0.4%). CAS patients who went on to ECA occlusion had an increased incidence of prior neck irradiation (50% vs 15%; P = .03), but we did not identify an association of ECA occlusion with ISR >50%.

CONCLUSIONS

Whereas prior publications have identified increased rates of external carotid stenosis, this is the first demonstration of increased ECA occlusion after CAS. However, ECA occlusion is uncommon (∼4%) and did not have an association with ISR >50%. Future work modeling ECA flow patterns before and after CAS will be used to further test this interaction.

State of the art in carotid artery stenting: trial data, technical aspects, and limitations

The volume of carotid artery stenting (CAS) safety and efficacy data has grown exponentially over the last decade. Recent comparative data with carotid endarterectomy, the utility of embolic protection devices, peri-procedural medications, basic technical aspects of CAS, developments in carotid stent design, potential complications of CAS, and complication risk factors are discussed in this review.

Carotid restenosis after endarterectomy and stenting: a critical issue?

BACKGROUND

Carotid artery stenting (CAS) is currently considered a valid alternative to carotid endarterectomy (CEA) for the prevention of stroke in high-risk patients. One of the most important issues for both of these techniques is carotid restenosis. The aim of our study was to evaluate the incidence of post-CEA and post-CAS restenosis in a large cohort of patients in a single high-volume center.

METHODS

Between December 2000 and December 2010, 2453 CEA and 2628 CAS procedures were performed in the Vascular and Endovascular Surgery Unit at our institution. The mean age of patients was 73.8 years (range 55‒89 years), 78% of whom were men. Indications for carotid revascularization were: presence of symptomatic carotid artery stenosis of >70%, or asymptomatic stenosis of at least 80%, especially in patients with vulnerable plaques.

RESULTS

Mild and long-term results after CEA and CAS were similar. The overall perioperative neurologic complication rate (minor and major stroke) was similar in the 2 groups. At 1-year follow-up the restenosis rate after CEA was 1.58%. In-stent restenosis after CAS occurred in 1.67% of the procedures. All but 3 arteries had been treated for postsurgical restenosis. All lesions were approached secondarily with endovascular procedures. Statistical analysis demonstrated that post-CEA restenosis was the most important predictive factor for the development of in-stent restenosis after CAS.

CONCLUSIONS

This review of our 10-year experience confirms that patients who develop restenosis after CEA are also prone to developing in-stent restenosis after CAS.

Agreement between site-reported and ultrasound core laboratory results for duplex ultrasound velocity measurements in the Carotid Revascularization Endarterectomy versus Stenting Trial

OBJECTIVE

Patients in the Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) had duplex ultrasound (DU) scans prior to treatment and during follow-up to document the severity of carotid disease and the anatomic outcome of carotid endarterectomy (CEA) or carotid artery stenting (CAS). An ultrasound core laboratory (UCL) reviewed DU data from the clinical sites. This analysis was done to determine the agreement between site-reported and UCL-verified DU velocity measurements.

METHODS

Clinical site DU worksheets, B-mode images, and Doppler velocity waveforms for the treated carotid arteries were reviewed at the UCL. The highest internal carotid artery peak systolic velocity (PSV) and associated Doppler angle were verified. If the angle was misaligned by >3 degrees, it was remeasured at the UCL and the PSV was recalculated. Agreement for PSV was defined as site-reported PSV within ± 5% of UCL-verified PSV. Transcription errors were corrected by the UCL but were not considered as disagreements. Follow-up analysis was limited to patients who received the assigned treatment.

RESULTS

The UCL reviewed 1702 prior-to-treatment and 1743 12-month follow-up DU scans (873 CEA, 870 CAS) from 111 clinical sites. Site-reported and UCL-verified PSV agreed in 1124 (66%) of the prior-to-treatment scans and 1200 (69%) of the follow-up scans. In those cases with a disagreement, Doppler angle accounted for disagreement in 339 (59%) of the prior-to-treatment scans and 277 (51%) of the follow-up scans. Based on a threshold PSV for ≥ 70% stenosis of ≥ 230 cm/s on the prior-to-treatment scans and ≥ 300 cm/s on the follow-up scans, UCL review resulted in reclassification of stenosis severity in 75 (4.4%) of the prior-to-treatment scans and 13 (0.75%) of the follow-up scans. There is evidence that the proportion of reclassification at follow-up was greater for CAS (10 scans; 1.2%) than for CEA (three scans; 0.34%) (P = .057).

CONCLUSIONS

There was a high rate of agreement between site-reported and UCL-verified DU results in CREST, and UCL review was associated with a low rate of stenosis reclassification. However, angle alignment errors were quite common and prompted recalculation of velocity in 20% of prior-to-treatment scans and 18% of follow-up scans. The use of a UCL provides a uniform process for DU interpretation and can identify sources of error and suggest technical improvements for future studies.

Analysis of restenosis after carotid artery stenting: preliminary results using computational fluid dynamics based on three-dimensional angiography

Currently carotid artery stenting (CAS) is a widely used technique for the treatment of carotid artery stenosis. However, some patients with restenosis following CAS have been reported, resulting in potential clinical problems. The purpose of this study was to investigate the hemodynamic changes before and after CAS to find the factors that may influence restenosis. Five patients (two with restenosis, three without restenosis) were included in this study. The geometry and rheological conditions of the carotid arteries were obtained from three-dimensional digital subtraction angiography and ultrasound measurements. Computational fluid dynamics (CFD) modelling was performed to calculate wall shear stress (WSS), wall shear stress gradient (WSSG) and internal carotid artery (ICA) flow ratio. In addition, morphologic analysis was carried out. CFD results indicated that the WSSG of the restenosis group was significantly larger than that of the no-restenosis group. In the restenosis group, the WSS distribution after CAS showed a significant variation at the ICA. The average ICA flow ratio of the restenosis group was 43.5%, while in the no-restenosis group it was 68.6%. Furthermore, there were similar significant differences between the two groups during morphology analysis. CFD technology is useful for physicians in estimating haemodynamic changes during ICA stenosis treatment. These parameters, including ICA flow ratio and WSS distribution, may help to predict carotid restenosis. In future, CFD combined with other medical techniques such as digital subtraction angiography, MRI and pathology technologies will be available for the clinical estimation of ICA restenosis.