Arterial remodeling and hemodynamics in carotid stents: a prospective duplex ultrasound study over 2 years

Evaluation of the self-expanding effect of carotid stents in the early postoperative period

PURPOSE

To evaluate the expansion effect of self-expandable stents during the first week after carotid artery stenting (CAS) procedure and to examine the variation of the effect according to the carotid plaque type.

METHODS

Seventy stenotic carotid arteries of 69 patients were stented by using self-expanding Wallstents with diameters of 7 and 9 mm, after detection of stenosis and plaque type by Doppler ultrasonography. Post-stent aggressive ballooning was avoided and residual stenosis rates were measured with digital subtraction angiography. After the stenting procedure, the caudal, narrowest, and cranial diameters of stents were measured with ultrasonography at 30 min, first day and first week. Stent diameter increase and change according to plaque type were evaluated. Two-way repeated measure ANOVA test was used for statistical analysis.

RESULTS

A significant increase was observed in the mean stent diameter in the three stent regions (caudal, narrow, and cranial) from the 30th minute to the first and seventh days (p < 0.001). The most prominent stent expansion occurred in the cranial and narrow segments within the first day. In the narrow stent region; Stent diameter increase between 30th minute-first day, 30th minute-first week, and first day-first week were all significant (p < 0.001). At 30 min, first day, and first week, no significant difference was detected between plaque type and stent expansion in caudal, narrow, and cranial regions (p = 0.286).

CONCLUSION

We think that keeping the lumen patency limited to 30% residual stenosis after CAS procedure by applying minimal post-stenting balloon dilatation and leaving the remaining lumen expansion to the self-expanding feature of the Wallstent might be a sensible approach in order to avoid embolic events and excessive carotid sinus reactions (CSR).

Self-Expanding Pulmonary Valves in 53 Patients With Native Repaired Right Ventricular Outflow Tracts

BACKGROUND

Self-expanding pulmonary valve grafts have been designed for percutaneous pulmonary valve implantation (PPVI) in patients with native repaired right ventricular (RV) outflow tracts (RVOTs). However, their efficacy, in terms of RV function and graft remodelling remain unclear.

METHODS

Patients with native RVOTs who received Venus P-valve (N = 15) or Pulsta valve (N = 38) implants between 2017 and 2022 were enrolled. We collected data on patient characteristics and cardiac catheterization parameters as well as imaging and laboratory data before, immediately after, and 6 to 12 months after PPVI and identified risk factors for RV dysfunction.

RESULTS

Valve implantation was successful in 98.1% of patients. The median duration of follow-up was 27.5 months. In the first 6 months after PPVI, all patients exhibited resolution of paradoxical septal motion and a significant reduction (P < 0.05) in RV volume, N-terminal pro-B-type natriuretic peptide levels, and valve eccentricity indices (-3.9%). Normalization of the RV ejection fraction (≥ 50%) was detected in only 9 patients (17.3%) and was independently associated with the RV end-diastolic volume index before PPVI (P = 0.03). Nine patients had residual or recurrent pulmonary regurgitation or paravalvular leak (graded as ≥ mild), which was associated with a larger eccentricity index (> 8%) and subsided by 12 months postimplantation.

CONCLUSIONS

We identified the risk factors likely to be associated with RV dysfunction and pulmonary regurgitation following PPVI in patients with native repaired RVOTs. RV volume-based patient selection is recommended for PPVI of a self-expanding pulmonary valve, along with monitoring of graft geometry.

Rates of Progression of Carotid In-Stent Stenosis and Clinical Outcome

BACKGROUND

We previously reported the incidence of ≥50% and ≥80% carotid in-stent stenosis. This study will analyze the rates of progression of in-stent stenosis and clinical outcome at later follow-up.

PATIENT POPULATION AND METHODS

This is a retrospective analysis of prospectively collected data of 450 transfemoral carotid artery stentings (TfCAS) at a later follow-up (a mean of 70 months). Progression of in-stent stenosis was defined as advancing to a higher severity of disease, i.e. <50% to ≥50% or ≥50% to ≥80%. A Kaplan Meier Analysis was used to estimate the rate of progression from <50% to ≥50%, ≥50% to ≥80%, overall rates of ≥50% and ≥80% in-stent stenosis, and survival at 1, 3, 5, and 10 years.

RESULTS

At a mean follow-up of 70.3 months (range: 1-222 months), 121/446 (27%) had ≥50% and 39 (8.7%) had ≥80% in-stent stenosis. Of those patients whose first duplex was normal or <50% (406), 82 progressed from normal/<50% to ≥50% in-stent stenosis. 82/406 (20.2%) of those that were normal or <50% in-stent stenosis progressed to ≥50% in-stent stenosis at a mean of 51.7 months (range: 1-213) and 14/121 (11.6%) of those with ≥50% stenosis progressed to ≥80% at a mean of 33.6 months (range: 6-89 months). Ten out of 82 (12%) of those who progressed from <50 to ≥50% had a neuro event (8 TIAs and 2 strokes). Two out of 14 (14.3%) of those that progressed from ≥50% to ≥80% had transient ischemic attacks (TIA), while the remaining patients were asymptomatic. Nine out of 39 patients (23%) with ≥80% in-stent stenosis had neurological events (eight TIAs and one contralateral stroke). Overall 13/121 patients with late ≥50% restenosis had a neurologic event (10.7%) (ten ipsilateral TIA, two ipsilateral stroke, and one contralateral stroke), i.e. 12 patients developed ipsilateral TIA/stroke out of 446 (2.7%) at a mean follow up of 70 months. Rates of freedom from <50% to ≥50% in-stent stenosis progression were 93%, 85%, 78%, and 66% at 1, 3, 5, and 10 years; and for progression from ≥50% to ≥80% in-stent stenosis were 89%, 81%, and 77% at 1, 3, and 5 years, respectively. The overall rates of freedom for ≥50% in-stent stenosis were 86%, 77%, 71%, and 59%; and for ≥80% in-stent stenosis were 96%, 93%, 91%, and 84%; and the stroke survival rates were 95%, 80%, 63%, and 31% at 1, 3, 5, and 10 years, respectively.

CONCLUSIONS

The rates of progression of carotid in-stent stenosis were modest, but had a low incidence of stroke events. Therefore, the utility of post-carotid artery stenting duplex surveillance should be selective and perhaps re-evaluated.

Long-term changes after carotid stenting assessed by intravascular ultrasound and near-infrared spectroscopy

BACKGROUND

Long-term effect of carotid stenting (CAS) on the stabilization of the plaque is almost unrecognized. Vascular healing and remodeling might seal the atherosclerotic plaque with neointimal hyperplasia decreasing the vulnerability. We aimed to assess long-term change in the lipid signal, stent and luminal dimensions and restenosis after CAS with the intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) imaging.

METHODS

We performed follow-up angiography and NIRS-IVUS imaging of 58 carotid stents in 52 patients. Median time from CAS to the follow-up examination was 31 months (range, 5-56). The lipid signal of the stented segment was calculated from a NIRS-derived chemogram (a spectroscopic map) as the lipid core burden index (LCBI, a dimensionless number from 0 to 1,000). Planimetric and volumetric measurements from IVUS were performed to assess change in minimal stent area (MSA), minimal luminal area (MLA), stent and luminal volume, late stent expansion and percentage in-stent restenosis (ISR) volume.

RESULTS

During the follow-up period, the mean (±SD) LCBI significantly decreased from 32±56 to 17±27 (P=0.002). The mean stent volume significantly increased from 717±302 to 1,019±429 mm3 (P<0.001) with mean stent expansion 43%±24%. The mean luminal volume increased from 717±302 to 760±359 mm3 (P=0.025) due to ISR encroaching 26%±15% of the stent volume.

CONCLUSIONS

Lipid signal decreased during the follow-up period suggesting stabilization of the plaque. Late stent expansion was balanced with neointimal hyperplasia.

TRIAL REGISTRATION

The trial is registered under clinicaltrials.gov NCT03141580.

Estimated Glomerular Filtration Rate as a Predictor of Restenosis After Carotid Stenting Using First-Generation Stents

This study evaluated the impact of the baseline estimated glomerular filtration rate (eGFR) on clinical and angiographic outcomes and long-term in-stent restenosis (ISR) rates in patients undergoing elective carotid artery stenting (CAS) procedures. Consecutive patients who underwent CAS were retrospectively enrolled (n = 456). At the end of 3 years of follow-up, patients who had died or were lost follow-up were excluded from the study and a final analysis was performed using data from the remaining 405 patients. The study population (n = 405) was divided into 3 tertiles based on the tertile values of the eGFR level (T1, T2, and T3); then, clinical and procedural characteristics and 3-year ISR rates were compared between the groups. An ISR of 50% was detected in 49 (12%) surviving patients. The 3-year ISR was higher among patients with the lowest eGFR values (T1) by 3.7 times (95% CI: 2.01-11.38) than that among patients with the highest eGFR values (T3). These significant relationships persisted following adjustment for confounders. A lower baseline eGFR level was significantly associated with an increased ISR rate. Decreased renal function may be a predictor of ISR after CAS using first-generation stents.

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.

Stent Design, Restenosis and Recurrent Stroke After Carotid Artery Stenting in the International Carotid Stenting Study

Background and Purpose- Open-cell carotid artery stents are associated with a higher peri-procedural stroke risk than closed-cell stents. However, the effect of stent design on long-term durability of carotid artery stenting (CAS) is unknown. We compared the medium- to long-term risk of restenosis and ipsilateral stroke between patients treated with open-cell stents versus closed-cell stents in the ICSS (International Carotid Stenting Study). Methods- Patients with symptomatic carotid stenosis were randomized to CAS or endarterectomy and followed with duplex ultrasound for a median of 4.0 years. We analyzed data from patients with completed CAS procedures, known stent design, and available ultrasound follow-up. The primary outcome, moderate or higher restenosis (≥50%) was defined as a peak systolic velocity of >1.3 m/s on ultrasound or occlusion of the treated internal carotid artery and analyzed with interval-censored models. Results- Eight hundred fifty-five patients were allocated to CAS. Seven hundred fourteen patients with completed CAS and known stent design were included in the current analysis. Of these, 352 were treated with open-cell and 362 with closed-cell stents. Moderate or higher restenosis occurred significantly less frequently in patients treated with open-cell (n=113) than closed-cell stents (n=154; 5-year risks were 35.5% versus 46.0%; unadjusted hazard ratio, 0.68; 95% CI, 0.53-0.88). There was no significant difference in the risk of severe restenosis (≥70%) after open-cell stenting (n=27) versus closed-cell stenting (n=43; 5-year risks, 8.6% versus 12.7%; unadjusted hazard ratio, 0.63; 95% CI, 0.37-1.05). The risk of ipsilateral stroke beyond 30 days after treatment was similar with open-cell and closed-cell stents (hazard ratio, 0.78; 95% CI, 0.35-1.75). Conclusions- Moderate or higher restenosis after CAS occurred less frequently in patients treated with open-cell stents than closed-cell stents. However, both stent designs were equally effective at preventing recurrent stroke during follow-up. Clinical Trial Registration- URL: http://www.isrctn.com/. Unique identifier: ISRCTN25337470.

Systematic and Comprehensive Comparison of Incidence of Restenosis Between Carotid Endarterectomy and Carotid Artery Stenting in Patients with Atherosclerotic Carotid Stenosis

OBJECTIVE

The purpose of the present study was to conduct a meta-analysis to systematically compare the incidence rates of in-stent restenosis after carotid artery stenting (CAS) and restenosis after carotid endarterectomy (CEA) for patients with atherosclerotic carotid stenosis.

METHODS

We retrieved potential academic reports comparing restenosis between CEA and CAS from the MEDLINE, PubMed, and EMBASE databases and the Cochrane Library from the date of the first CEA (January 1951) to July 20, 2018. The references of the identified studies were carefully reviewed to ensure that all available reports were included in the present study.

RESULTS

Our meta-analysis included 27 studies (15 randomized controlled trials, 12 nonrandomized controlled trials) and 20,479 participants with atherosclerotic carotid stenosis. A statistically significant difference was found in the cumulative incidence of restenosis >70% between CEA and CAS (risk difference, -0.033, 95% confidence interval [CI] -0.054 to -0.013; P = 0.002). For the restenosis >70% outcomes, although CEA was relevant with a lower rate of restenosis than CAS within 6 months (odds ratio [OR], 0.495; 95% CI, 0.285-0.861; P = 0.013) and 1 year (OR, 0.626; 95% CI, 0.483-0.811; P < 0.001), no statistically significant differences were found at 1.5 years (P = 0.210), 2 years (P = 0.123), 4 years (P = 0.124), 5 years (P = 0.327), or 10 years (P = 0.839). For the restenosis >50% outcomes, a significant difference was found in the rate of restenosis between the CEA and CAS groups within 1 year (OR, 0.317; 95% CI, 0.228-0.441; P < 0.001) but not at 1.5 years (P = 0.301), 2 years (P = 0.686), or 5 years (P = 0.920). No nominally significant effects were demonstrated with respect to the cumulative incidence of occlusion (P = 0.195) or the cumulative incidence of restenosis for symptomatic patients (P = 0.170) between CEA and CAS.

CONCLUSIONS

Although CAS was preferred over CEA, regardless of restenosis >50% or >70% after revascularization within 1 year, no significant difference was observed with extension of the follow-up period to >1 year. CAS was not associated with a greater cumulative incidence of occlusion or the cumulative incidence of restenosis for symptomatic patients.

In-stent hypodense area at two weeks following carotid artery stenting predicts neointimal hyperplasia after two years

Introduction It has not been reported how long the follow-up study after carotid artery stenting (CAS) should be continued. The purpose of the present study is to clarify the dynamic change of the in-stent neointimal layer and residual arterial lumen by two years following CAS using three-dimensional computed tomography angiography (3D CTA) with volume rendering. Methods Thirty-six stented carotid arteries in 34 consecutive patients were examined by 3D CTA with volume rendering at two weeks and 3, 6, 12, 24 months of follow-up. Results An in-stent hypodense area could be detected in 10 of 36 (27.8%) carotid arteries at two weeks after CAS. In-stent hypodense areas gradually declined thereafter by three months. In the course of longer follow-up, the layer of the in-stent hypodense area (neointimal hyperplasia) continued to grow in size for up to 24 months. Patients with an in-stent hypodense area at two weeks have a thicker layer of neointimal hyperplasia at 24 months than patients without in-stent hypodense area at two weeks' follow-up. The predictive factors for growing neointimal hyperplasia at 24 months in multiple regression analysis are ulcer formation in pretreatment stenosis and the thickness of in-stent hypodense area at two weeks following CAS. Conclusion Our results suggest that follow-up study should be continued for a longer period even if in-stent restenosis could not be detected at one year following CAS. Especially in cases with ulcer formation in pretreatment stenosis and with a subacute in-stent hypodense area after CAS, longer follow-up is strongly recommended.

Effect of Self-Expanding Carotid Stents on Plaque Thickness and Vessel Diameter

BACKGROUND

In vitro models have suggested that stents affect atherosclerotic plaques symmetrically because of their outward radial forces. We evaluated the effects of stents on carotid plaque and the arterial wall using carotid ultrasound in carotid stenting patients to see whether these effects were borne out in vivo.

METHODS

From a carotid stent database, 30 consecutive patients were selected. All had carotid Doppler ultrasound performed pre- and poststenting. The diameters of the lumen at the level of stenotic plaque pre- and poststenting, the dorsal and ventral plaque thickness, and of the outer arterial wall diameter were measured. Plaque thickness was measured at the level of maximal stenosis. Nonparametric tests were used to determine whether the stent effect and luminal enlargement were based on wall remodeling or on total arterial expansion.

RESULTS

The patients were followed for an average of 22 months. Eighteen patients were male, with an average age of 70 years. A total of 87% of patients were symptomatic ipsilateral to the side of stenosis. Nine patients had angioplasty intraprocedurally. The luminal diameter increased poststenting in the region of severe stenosis. Plaque thickness, both ventrally and dorsally, decreased poststenting, with no significant difference between the ventral and dorsal plaque effects. The outer arterial wall diameters did not change. The measured lumen in the stent increased over time poststenting.

CONCLUSIONS

Self-expanding nitinol stents alter the baseline ventral and dorsal plaque to a significant degree and do not significantly affect the native arterial wall and the overall arterial diameter.

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

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

Collagen Matrix Remodeling in Stented Pulmonary Arteries after Transapical Heart Valve Replacement

The use of valved stents for minimally invasive replacement of semilunar heart valves is expected to change the extracellular matrix and mechanical function of the native artery and may thus impair long-term functionality of the implant. Here we investigate the impact of the stent on matrix remodeling of the pulmonary artery in a sheep model, focusing on matrix composition and collagen (re)orientation of the host tissue. Ovine native pulmonary arteries were harvested 8 (n = 2), 16 (n = 4) and 24 (n = 2) weeks after transapical implantation of self-expandable stented heart valves. Second harmonic generation (SHG) microscopy was used to assess the collagen (re)orientation of fresh tissue samples. The collagen and elastin content was quantified using biochemical assays. SHG microscopy revealed regional differences in collagen organization in all explants. In the adventitial layer of the arterial wall far distal to the stent (considered as the control tissue), we observed wavy collagen fibers oriented in the circumferential direction. These circumferential fibers were more straightened in the adventitial layer located behind the stent. On the luminal side of the wall behind the stent, collagen fibers were aligned along the stent struts and randomly oriented between the struts. Immediately distal to the stent, however, fibers on both the luminal and the adventitial side of the wall were oriented in the axial direction, demonstrating the stent impact on the collagen structure of surrounding arterial tissues. Collagen orientation patterns did not change with implantation time, and biochemical analyses showed no changes in the trend of collagen and elastin content with implantation time or location of the vascular wall. We hypothesize that the collagen fibers on the adventitial side of the arterial wall and behind the stent straighten in response to the arterial stretch caused by oversizing of the stent. However, the collagen organization on the luminal side suggests that stent-induced remodeling is dominated by contact guidance.

An Optical Coherence Tomography Assessment of Stent Strut Apposition Based on the Presence of Lipid-Rich Plaque in the Carotid Artery

Purpose: To evaluate the rate of stent malapposition, plaque prolapse, and fibrous cap rupture detected by optical coherence tomography (OCT) after carotid artery stenting (CAS) based on the presence of lipid-rich plaque, which may be associated with acute stent thrombosis. Methods: A retrospective study was conducted involving 26 consecutive patients who underwent CAS with OCT imaging acquired before stent deployment and after stent dilation. Adequate imaging quality could not be obtained in 6 patients (out-of-screen images and residual blood), which left 20 patients (mean age 63 years; 13 men) for analysis. Plaque characteristics were determined from 500 selected OCT cross sections; a lipid-rich plaque was defined by lipid present in ≥2 quadrants. Cross-sectional OCT images within the stented segment were evaluated at 1-mm intervals for the presence of malapposition, plaque prolapse, and fibrous cap rupture. The data were compared between patients with and without lipid-rich plaques. The patients were examined at 6 months to determine the degree of in-stent restenosis (ISR). Results: Patients with lipid-rich plaque demonstrated a higher rate of embedded stent struts (29.4% vs 23.7%, p<0.001) and a lower rate of well apposed struts (54.6% vs 59.6%, p<0.001) compared to patients with non–lipid-rich plaque. Rates of plaque prolapse (65.5% vs 49.1%, p<0.001) and fibrous cap rupture (65.5% vs 49.1%, p<0.001) were significantly higher in patients with lipid-rich plaque. ISR ranged from none to 42% in 12 patients; malapposed stent struts and fibrous cap ruptures were not more frequent in the patients with obvious ISR. The 8 patients with no obvious restenosis still had malapposed struts, embedded struts, plaque prolapse, and fibrous cap rupture. Conclusion: Embedded stent struts, plaque prolapse, and fibrous cap rupture were more frequent and well-apposed stent struts were less frequent after CAS in patients with lipid-rich plaque.

Predictors of restenosis after carotid artery stenting in 241 cases

Background

Variable rates of restenosis after carotid artery stenting (CAS) have been reported, and few predictors have been suggested. Because CAS is being performed with increasing frequency, more data are needed to evaluate the rate and predictors of restenosis and possibly identify new risk factors for restenosis after CAS. The aim of this study was to analyze the rate and predictors of restenosis after CAS.

Methods

241 patients with carotid artery stenosis treated with stenting were analyzed retrospectively to identify patients who had restenosis after stenting. Univariate analysis and multivariate logistic regression were conducted to determine the predictors of restenosis.

Results

Mean patient age was 67.5 years. 8.3% of patients who underwent CAS had carotid restenosis of ≥50% during follow-up. 3.7% of patients required retreatment. Mean duration from CAS to retreatment was 11 months. In multivariate analysis, the predictors of restenosis included history of cardiovascular disease (OR=8.88, p<0.001) and having a cerebrovascular accident (CVA) prior to stenting (OR=1.87, p=0.034). A higher percentage of preoperative carotid stenosis was associated with higher odds of restenosis in univariate analysis (p=0.04, OR stenosis ≥80%=5.7).

Conclusions

Our results suggest that the rate of carotid restenosis after stenting is low. Patients with cardiovascular disease, patients who had a CVA prior to stenting, and patients with higher percentages of preoperative stenosis had higher odds of restenosis. Higher rates of restenosis should be kept in mind when opting for CAS in these patients.

Plaque morphology detected with Duplex ultrasound before carotid angioplasty and stenting (CAS) is not a predictor of carotid artery in-stent restenosis, a case control study

Background

In-stent restenosis (ISR) is an important factor endangering the long-term safety and efficacy of carotid artery angioplasty and stenting (CAS). It is plausible that soft vulnerable plaques are more likely to be injured during CAS procedure and are therefore more likely to initiate the cascade finally leading to ISR. The aim of this study was to investigate if plaque morphology detected by a simple applicable Duplex ultrasound score before CAS can be used as a predictor for ISR.

Methods

Within a prospectively collected single-centre CAS database of 281 patients (comprising 300 arteries) with high-grade carotid artery stenosis, who underwent CAS between May 2003 and January 2013, we conducted a nested case–control study. Plaque morphology before CAS was analysed by a blinded investigator and each parameter of the Total Plaque Risk Score (TPRS) as well as the whole score was evaluated with regard to its diagnostic validity for ISR.

Results

We analysed the data of 10 patients with ISR and 50 patients without ISR. There were no significant differences with respect to baseline characteristics, vascular risk factors, and degree of stenosis between patients with and without ISR. The duration of follow-up was longer in patients with ISR (p = 0.024) and these patients were more likely to show increased PSV (p = 0.012) immediately after CAS than patients without ISR. Neither individual parameters of the TPRS score nor the score as a whole were suitable as a diagnostic test for ISR development.

Conclusions

In the present study we could demonstrate that the non-contrast enhanced DUS of the pre-interventional plaque formation cannot be used as a predictor for the development of ISR. Evaluating a more sophisticated, but not routinely available approach e.g. by ultrasound based plaque perfusion imaging or CT based plaque analysis could be helpful in the future in order to assess the role of plaque morphology in the context of ISR development.

Angiographic lumen changes associated with oversized intracranial stent implantation for aneurysm treatment

BACKGROUND

The effect of oversized intracranial stent implantation, and potential excessive neointimal hyperplasia from the chronic outward radial force, has not been reported. We sought to compare the angiographic narrowing associated with implantation of oversized stents.

METHODS

We reviewed an aneurysm database and identified patients treated with stent-assisted embolization involving a vessel size transition. Demographics and lesion characteristics were extracted. The relationship between lumen diameter and stent oversizing was compared.

RESULTS

Twenty vessels were identified in 18 patients, providing 80 paired data points. Mean follow-up time was 8 months (SD 6). The average oversizing in the smaller diameter parent vessel landing-zone was 1.75 mm. Mean change in lumen size from pre-stent implantation was not significantly different for any of the four sites. There was a significant difference in change of lumen size at the stent tines when compared with the respective mid-stent segment for both the proximal (P = 0.02) and distal (P = 0.0004) landing zones.

CONCLUSIONS

A small significant lumen loss occurs at stent tines when compared to midstent struts. However, there is no overall significant stenosis from highly oversized stents. Persistent luminal gain from the oversized stent radial force likely predominates over any neointimal hyperplasia.

Characteristics of duplex sonographic parameters over time after successful carotid artery stenting

OBJECTIVES

Carotid duplex sonography is the primary tool for surveillance after carotid artery stenting, but the course of sonographic velocities over time after successful stenting is unclear. The purpose of this study was to describe carotid duplex sonographic velocity parameters after successful carotid artery stenting and to determine the predictors of poststent sonographic velocities.

METHODS

We queried institutional carotid stent and noninvasive vascular laboratory databases for internal carotid artery stents placed between January 2004 and June 2007. We included patients with stenosis of 20% or less on completion angiograms who had carotid duplex sonography within 30 days before and 7 days after stenting. The prestent peak systolic velocity (PSV), end-diastolic velocity (EDV), internal-to-common carotid artery PSV ratio, contralateral internal carotid artery velocities, stent type, open- versus closed-cell stent design, and days of follow-up were tested as potential predictors of poststent velocities.

RESULTS

Eighty-two of 498 patients met inclusion criteria. The mean PSV and PSV ratio decreased from 423.6 cm/s and 7.1 before stenting to 98.5 cm/s and 1.3 after stenting (both P < .001). During a median follow-up of 370 days, poststent velocities remained stable. All poststent velocities (PSV, EDV, and PSV ratio) were dependent on prestent ipsilateral and contralateral velocities. The poststent EDV was dependent on the type of stent. The upper range for 0% to 20% stenosis in the stented internal carotid artery was a PSV of 141 cm/s, an EDV of 42 cm/s, and a PSV ratio of 2.1 or lower.

CONCLUSIONS

With a median follow-up of 1 year, the PSV and PSV ratio remained stable over time in successfully stented carotid arteries. Deviations in sonographic parameters after initial poststent carotid duplex sonography should prompt an investigation for possible in-stent restenosis.

Finite Element Analysis of the Implantation of a Self-Expanding Stent: Impact of Lesion Calcification

In this work, the deployment of a self-expanding stent in a stenosed artery was evaluated through finite element analysis. The three-layered structure of the artery and their material properties were measured and implemented in our computational models. The instant outcomes, including lumen gain, tissue prolapse, and stress distribution, were quantified, and the effect of plaque calcification was evaluated. Results showed that the peak wall stress occurred on the media layer regardless of plaque calcification. The calcified plaque mitigated the tissue prolapse and arterial wall stresses in general, compared with the soft plaque. However, the lesion calcification led to a more severe residual stenosis, dogboning effect, and corresponding edge stress concentrations after stenting, which requires pre- and/or post-surgical management.

The current role of carotid duplex ultrasonography in the management of carotid atherosclerosis: foundations and advances

The management of atherosclerotic carotid occlusive disease for stroke prevention has entered a time of dramatic change. Improvements in medical management have begun to challenge traditional interventional approaches to asymptomatic carotid stenosis. Simultaneously, carotid artery stenting (CAS) has emerged as an alternative to carotid endarterectomy (CE). Finally, multiple factors beyond degree of stenosis and symptom status now mitigate clinical decision making. These factors include brain perfusion, plaque morphology, and patency of intracranial collaterals (circle of Willis). With all of these changes, it seems prudent to review the role of carotid duplex ultrasonography in the management of atherosclerotic carotid occlusive disease for stroke prevention. Carotid duplex ultrasonography (CDU) for initial and serial imaging of the carotid bifurcation remains an essential component in the management of carotid bifurcation disease. However, correlative axial imaging modalities (computer tomographic angiography (CTA) and contrast-enhanced magnetic resonance angiography (CE-MRA)) increasingly aid in the assessment of individual stroke risk and are important in treatment decisions. The purpose of this paper is twofold: (1) to discuss foundations and advances in CDU and (2) to evaluate the current role of CDU, in light of other imaging modalities, in the clinical management of carotid atherosclerosis.

Acute lower limb ischaemia due to delayed upstream migration of an iliac stent

We report a case of acute limb ischaemia due to unusual upstream stent migration into the aorta 2 years after successful kissing stenting. Angiography showed a misplacement of both common iliac stent into the aorta, upstream migration with a fracture on the left external iliac stent into the iliac common artery, occlusion of the left iliac and femoral artery, dilatation of aortic bifurcation and stent separation on the right side. The patient underwent a successful axillo-bifemoral bypass graft. Vessel wall remodelling due to overestimation of stent size, aortic turbulence and rebound effect may explain this complication.

Angiographically confirmed stent over expansion in the internal carotid artery during stenting: incidence, predictors, and outcomes

INTRODUCTION

Selection of the appropriate diameter of stent is difficult in patients with the size mismatch between the internal carotid artery (ICA) and the common carotid artery (CCA). Although stent overexpansion (SOE) in the ICA after carotid artery stenting (CAS) is suspected of producing restenosis, SOE has not been well established. We discuss its incidence, predictors, and outcomes.

METHODS

We retrospectively reviewed follow-up angiographs of 206 CAS-treated arteries in 201 patients who had undergone CAS. SOE was defined as angiographic evidence of an intimal gap between the non-stented normal and the dilated stented ICA at the distal stent edge. We also collected data on the patients' clinical status, comorbidities, and radiological and procedural data. Patients with SOE were further followed up closely by duplex ultrasound scans.

RESULTS

SOE was detected in nine of 206 CAS-treated ICAs (4.4%). Univariate analysis revealed a significant association between SOE and open-cell stents, the stent diameter (p < 0.01), pre-procedural stenosis, the ICA diameter, ICA/CCA ratio, and the ICA/stent ratio (p < 0.05). Entering these variables into a logistic regression model, open-cell stents were the only variable that significantly increased the risk for SOE (OR 2.36; 95% CI 0.99-4.60; p < 0.05). During a mean clinical follow-up of 31.1 months (range 24-39 months), none of the patients with SOE developed new neurologic ischemic symptoms, stent-edge stenosis, or in-stent restenosis.

CONCLUSION

SOE after CAS was not associated with clinical adverse effects. This study suggests that the diameter of stent should be determined by reference to the CCA diameter without respect to the ICA diameter.

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.

Morphological and hemodynamic patterns of carotid stenosis treated by endarterectomy with patch closure versus stenting: a duplex ultrasound study

OBJECTIVES

A duplex ultrasound study was performed to investigate morphological and hemodynamic patterns of carotid stenoses treated by endarterectomy with patch closure versus stenting.

MATERIALS AND METHOD

Twenty-nine carotid stenoses were treated with stenting and 65 with patch closure. Duplex ultrasound parameters (luminal diameter, mm; peak systolic velocity and end-diastolic velocity, cm/s) were measured 24 hours after the procedures and also at 12 months post-procedure. Residual stenoses (immediately postprocedure) and restenoses (within 12 months of procedure) were defined as narrowings of ≥ 50% on duplex ultrasound examination.

RESULTS

In stented patients, the luminal diameter of the proximal internal carotid artery increased in the interval between the 24-hour and 12-month post-procedure studies, while in the patch closure patients, the diameter decreased. Carotid hemodynamics normalized immediately after both patching and stenting and remained relatively stable thereafter up to 12 months. No statistically elevated flow velocities (in the absence of residual stenosis or restenosis) were observed in the patched or stented carotid arteries. No significant differences in residual stenosis rates were observed between the stenting group (3 cases, 10.34%) and the patch closure group (1 case, 1.53%, P = 0.08). At 12 months, 2 stenting patients (6.88%) and 2 patch closure patients (3.07%) had $50% restenosis (P = 0.58). One case of late stroke due to restenosis was observed in the stenting group; the patient died 12 months postoperatively, before receiving new intervention.

CONCLUSION

Measurements over time in luminal diameter signalized differences in arterial remodeling mechanisms between patched and stented carotids. Both stenting and patch closure were associated with carotid patency and flow restoration. This study does not support a general approach to new velocity criteria indiscriminately applied to stented or patched carotids.

Recurrent subacute in-stent restenosis after carotid artery stenting due to plaque protrusion

A 70-year-old male presented with transient ischemic attacks manifesting as right hemiparesis and motor aphasia due to severe left cervical internal carotid artery stenosis. Carotid artery stenting (CAS) using a flow-reversal system was performed without complications. However, the patient exhibited transient right hemiparesis and motor aphasia 10 days after CAS. Emergent angiography demonstrated in-stent restenosis. In-stent percutaneous transluminal angioplasty and CAS were performed successfully using a distal protection system. However, duplex ultrasound scanning revealed progressive in-stent restenosis, 3 and 6 days after the re-treatment. Emergent angiography again demonstrated in-stent restenosis. Urgent stent removal and carotid endarterectomy were performed. Plaque had prolapsed through the stent. Histological examination revealed that the specimen was mainly plaque consisting of cholesterol crystals and macrophages. The patient was able to return to independent life without neurological deficit. Repeated endovascular surgery with appropriate antiplatelet and anticoagulation therapy should be attempted initially to treat in-stent restenosis. Endarterectomy with stent removal should be considered as a rescue option, especially if plaque protrusion is identified.

Late stent expansion and neointimal proliferation of oversized Nitinol stents in peripheral arteries

For peripheral endovascular intervention, self-expanding (SE) stents are commonly oversized in relation to target arteries to assure optimal wall apposition and prevent migration. However, the consequences of oversizing have not been well studied. The purpose of this study was to examine the effects of SE stent oversizing (OS) with respect to the kinetics of late stent expansion and the long-term histological effects of OS. Pairs of overlapped 8 x 28-mm Nitinol SE stents were implanted into the iliofemoral arteries of 14 Yucatan swine. Due to variations in target artery size, the stent-to-artery ratio ranged from 1.2:1 to 1.9:1. Lumen and stent diameters were assessed by quantitative angiography at the time of implantation. Following angiographic assessment at 6 months, stented arteries were perfusion-fixed, sectioned, and stained for histological analysis. Immediately following implantation, the stents were found to be expanded to a range of 4.7-7.1 mm, largely conforming to the diameter of the recipient target artery. The stents continued to expand over time, however, and all stents had enlarged to nearly their 8-mm nominal diameter by 6 months. The histological effects of OS were profound, with marked increases in injury and luminal area stenosis, including a statistically significant linear correlation between stent-to-artery ratio and area stenosis. In this experimental model of peripheral endovascular intervention, oversized Nitinol SE stents are constrained by their target artery diameter upon implantation but expand to their nominal diameter within 6 months. Severe OS (stent-to-artery ratio >1.4:1) results in a profound long-term histological response including exuberant neointimal proliferation and luminal stenosis.

Vascular Remodeling After Carotid Artery Stenting

Carotid stenting is an alternative to endarterectomy for the treatment of carotid stenosis. To determine the role of vascular remodeling after stent placement, we studied 19 high surgical risk patients undergoing carotid stenting for severe stenosis. Using high-resolution ultrasound, we evaluated the intima-media thickness (IMT), the intima-intima diameter, and the adventitia-adventitia diameter at prespecified sites of the carotid artery tree during 3 years of follow-up. The IMT of internal carotid artery, at the site of maximum stenosis, increased significantly from 0 mm after 24 hours, to 0.41 mm at 3 months, to 0.48 mm at 6 months, and to 0.51 mm at 3 years of follow-up. In the same site, diameters and residual stenosis (range 29-24%) did not change over time. Our study showed that stent is self-expanding against the atherosclerotic plaque within the 3-year follow-up period. Despite neointima formation, the intima-intima diameter does not change without worsening of the residual stenosis.

Duplex scan surveillance after carotid angioplasty and stenting: A rational definition of stent stenosis

OBJECTIVE

A duplex ultrasound (DUS) surveillance algorithm used after carotid endarterectomy (CEA) was applied to patients after carotid stenting and angioplasty (CAS) to determine the incidence of high-grade stent stenosis, its relationship to clinical symptoms, and the outcome of reintervention.

METHODS

In 111 patients who underwent 114 CAS procedures for symptomatic (n = 62) or asymptomatic (n = 52) atherosclerotic or recurrent stenosis after CEA involving the internal carotid artery (ICA), DUS surveillance was performed <or=30 days and every 6 months thereafter. High-grade stenosis (peak systolic velocity [PSV] >300 cm/s, diastolic velocity >125 cm/s, internal carotid artery stent/proximal common carotid artery ratio >4) involving the stented arterial segment prompted diagnostic angiography and repair when >75% diameter-reduction stenosis was confirmed. Criteria for >50% CAS stenosis was a PSV >150 cm/s with a PSV stent ratio >2.

RESULTS

All 114 carotid stents were patent on initial DUS imaging, including 90 (79%) with PSV <150 cm/s (94 +/- 24 cm/s), 23 (20%) with PSV >150 cm/s (183 +/- 34 cm/s), and one with high-grade, residual stenosis (PSV = 355). During subsequent surveillance, 81 CAS sites (71%) exhibited no change in stenosis severity, nine sites demonstrated stenosis regression to <50% diameter reduction, and five sites developed velocity spectra of a high-grade stenosis. Angiography confirmed >75% diameter reduction in all six CASs with DUS-detected high-grade stenosis, all patients were asymptomatic, and treatment consisted of endovascular (n = 5) or surgical (n = 1) repair. During the mean 33-month follow-up period, three patients experienced ipsilateral, reversible neurologic events at 30, 45, and 120 days after CAS; none was associated with severe stent stenosis. No stent occlusions occurred, and no patient with >50% CAS stenosis on initial or subsequent testing developed a permanent ipsilateral permanent neurologic deficit or stroke-related death.

CONCLUSION

DUS surveillance after CAS identified a 5% procedural failure rate due to the development of high-grade in-stent stenosis. Both progression and regression of stent stenosis severity was observed on serial testing, but 70% of CAS sites demonstrated velocity spectra consistent with <50% diameter reduction. The surveillance algorithm used, including reintervention for asymptomatic high-grade CAS stenosis, was associated with stent patency and the absence of disabling stroke.

Risk factors for restenosis after carotid artery angioplasty and stenting

OBJECTIVES

With carotid artery stenting (CAS) becoming an ever-increasing procedure, we sought to determine risk factors for in-stent restenosis after CAS.

METHODS

Consecutive patients undergoing CAS between January 2002 and October 2004 at a tertiary care hospital were retrospectively reviewed. Patient, filter, and stent selection were left to the discretion of the attending surgeon. High-risk patients were defined by significant comorbidities or a hostile neck (prior surgery or radiation, or both), and risk factor analysis was performed. In-stent restenosis was defined as >60%, and selective angiography was performed on patients with an in-stent restenosis >80% by duplex ultrasound imaging.

RESULTS

Reviewed were 101 patients (55 men, 46 women) who underwent 109 CAS procedures. Comorbidities were typical for patients with atherosclerosis. In addition, 38% (n = 41) of procedures were performed in patients who had prior neck surgery, of which 29% (n = 32) had previous ipsilateral carotid endarterectomy. Seventeen patients (16%) had a history of neck cancer, and all had prior neck radiation. Median follow-up was 5 months (range, 0 to 30 months). Neurologic complications included three transient ischemic attacks (2.8%) and one nondisabling stroke (0.9%). There were two myocardial infarctions (1.9%) and no periprocedural deaths (30 days), for a combined stroke, myocardial infarction, and death rate of 2.9%. Asymptomatic in-stent restenosis developed in 12 carotids (11%), five of which required endovascular intervention, with a mean of 6 months to restenosis. Univariate Cox proportional hazard regression models were used to determine risk factors for the development of restenosis. Prior stroke, transient ischemic attack, amaurosis fugax, and prior neck cancer were all significant risk factors. When these significant risk factors from univariate analysis were put into multivariate analysis, however, the only marginally significant risk factor was prior neck cancer (P = .06). Kaplan-Meier analysis revealed a cumulative freedom from in-stent restenosis at 24 months of 88% +/- 6% in patients without neck cancer compared with 27% +/- 17% (P = .02) in patients with neck cancer.

CONCLUSIONS

CAS has been shown to be safe and effective in high-risk patients, with minimal adverse events.

Mechanisms and predictors of carotid artery stent restenosis: a serial intravascular ultrasound study

OBJECTIVES

The aim of this study was to determine the mechanisms and predictors of carotid artery restenosis after carotid artery stenting (CAS) using serial intravascular ultrasound (IVUS) imaging.

BACKGROUND

Carotid artery stenting is increasingly used to treat high-grade obstructive carotid disease, but our knowledge of carotid in-stent restenosis and remodeling remains limited.

METHODS

Post-procedural and 6-month (median 6 months) follow-up quantitative carotid angiography and IVUS were performed after self-expanding stent deployment in 50 internal carotid arteries (ICA). The IVUS measurements at multiple designated sites included minimal luminal diameter, lumen area, stent area (SA), and neointimal hyperplasia area (NIH).

RESULTS

Late stent enlargement at follow-up was found at all segments, and the percentage increase was greatest at the ICA lesion site (mean +/- SD, 48.9 +/- 35.3%). The NIH, expressed as a percentage of SA, was seen within all segments of the stent and was greatest at the ICA lesion site (37.3 +/- 23.3%). There was a strong positive correlation between the amount of NIH and late stent enlargement (r = 0.64; p < 0.001). Immediate post-procedural minimum ICA SA (r = -0.37; p < 0.01) and stent expansion (r = -0.44; p = 0.001) correlated negatively with the percentage restenotic area at follow-up.

CONCLUSIONS

Although self-expanding carotid stents generate considerable neointimal hyperplasia, the process is balanced by marked late stent enlargement. Small stent dimensions immediately post-procedure were associated with a higher risk of restenosis.

Management of in-sent restenosis after carotid artery stenting in high-risk patients

BACKGROUND

Carotid artery stenting (CAS) has emerged as an acceptable treatment alternative in patients with carotid bifurcation disease. Although early results of CAS have been promising, long-term clinical outcomes remain less certain. We report herein the frequency, management, and clinical outcome of in-stent restenosis (ISR) after CAS at a single academic institution.

METHODS

Clinical records of 208 CAS procedures in 188 patients with carotid stenosis of 80% or greater, including 48 (26.5%) asymptomatic patients, during a 42-month period were analyzed. Follow-up serial carotid duplex ultrasound scans were performed. Selective angiography and repeat intervention were performed when duplex ultrasound scans showed 80% or greater ISR. Treatment outcomes of ISR interventions were analyzed.

RESULTS

Over a median 17-month follow-up, 33 (15.9%) ISRs of 60% or greater were found, according to the Doppler criteria. Among them, seven patients (3.4%) with a mean age of 68 years (range, 65-87 years) developed high-grade ISR (> or =80%), and they all underwent further endovascular interventions. Six patients with high-grade ISR were asymptomatic, whereas one remaining patient presented with a transient ischemic attack. Five of seven ISRs occurred within 12 months of CAS, and two occurred at 18 months' follow-up. Treatment indications for initial CAS in these seven patients included recurrent stenosis after CEA (n = 4), radiation-induced stenosis (n = 1), and high-cardiac-risk criteria (n = 2). Treatment modalities for ISR included balloon angioplasty alone (n = 1), cutting balloon angioplasty alone (n = 4), cutting balloon angioplasty with stent placement (n = 1), and balloon angioplasty with stent placement (n = 1). Technical success was achieved in all patients, and no periprocedural complications occurred. Two patients with post-CEA restenosis developed restenosis after ISR interventions, both of whom were successfully treated with cutting balloon angioplasty at 6 and 8 months. The remaining five patients showed an absence of recurrent stenosis or symptoms during a mean follow-up of 12 months (range, 3-37 months). By using the Kaplan-Meier analysis, the freedom from 80% or greater ISR after CAS procedures at 12, 24, 36, and 42 months was 97%, 97%, 96%, and 94%, respectively.

CONCLUSIONS

Our study showed that ISR after CAS remains uncommon. Successful treatment of ISR can be achieved by endovascular interventions, which incurred no instance of periprocedural complications in our series. Patients who developed ISR after CEA were likely to develop restenosis after IRS intervention. Diligent ultrasound follow-up scans are important after CAS, particularly in patients with post-CEA restenosis.