Stent Fractures After Superficial Femoral Artery Stenting

Design and use of an ex vivo peripheral simulating bioreactor system for pharmacokinetic analysis of a drug coated stent

Currently, there are no ex vivo systems that can model the motion of peripheral arteries and allow for the evaluation of pharmacokinetics (PK) of endovascular devices. The objective of this study was to develop a novel peripheral simulating bioreactor system to evaluate drug pharmacokinetics of stents. We utilized 3D-printed and off-the-shelf components to construct a peripheral-simulating bioreactor system capable of mimicking the motion of peripheral arteries. Servo motors were primarily used to shorten/elongate, twist, and bend explanted porcine carotid arteries. To evaluate the pharmacokinetics in the bioreactor, drug-eluting stents were deployed within explanted arteries and subjected to vascular motion along with pulsatile flow conditions. Following 30 min and 24 h, the arteries were removed, and paclitaxel levels were measured. Scanning electron microscopy was also performed to evaluate the stent surface. Arterial paclitaxel levels of the stent-treated arteries were found to be higher at 30 min than at 24 h following pulsatile and no vascular motion and even higher at 24 h following pulsatile flow and vascular motion. The residual drug on the stent significantly decreased from 30 min to 24 h. Scanning electron microscopy confirmed the loss of paclitaxel coating at 24 h and greater disturbance in stents under peripheral motion versus pulsatile only. This system represents the first ex vivo system to determine the PK of drug-eluting stents under physiological flow and vascular motion conditions. This work provides a novel system for a quick and inexpensive preclinical tool to study acute drug tissue concentration kinetics of drug-releasing interventional vascular devices designed for peripheral applications.

Treatment of Long Femoropopliteal Occlusive Lesions With Self-expanding Interwoven Nitinol Stent: 24 Month Outcomes of the STELLA-SUPERA-SIBERIA Register Trial

PURPOSE

The efficacy and safety of the Supera stent in superficial femoral artery (SFA) have been reported mostly in shorter lesions with relatively low proportion of occlusions. There are little data on the effectiveness of the Supera stent in long lesions. The aim of this study was to assess the clinical safety and efficiency of the Supera stent in the treatment of long femoropopliteal occlusive lesions (Trans-Atlantic Inter-Society Consensus [TASC] C/D) in patients with symptomatic peripheral artery disease.

MATERIALS AND METHODS

The STELLA-SUPERA-SIBERIA is a prospective, single-center, single-arm study. Patients with symptomatic (Rutherford stages 3-6) de novo and TASC C/D occlusive lesions of the femoropopliteal segment were treated with Supera stent. The primary endpoint was the 12 month rate of primary sustained clinical improvement (upward shift on the Rutherford classification to a one level without the need for repeated target lesion revascularization (TLR) in surviving patients without the need for unplanned amputation). Secondary endpoints were the 24 month of primary sustained clinical improvement, MALE, limb salvage, the primary patency, the secondary patency, 24 month MACE. Follow-up included clinical examination, duplex scan, and biplane x-ray up to 24 months.

RESULTS

Between April 2019 and January 2020, 52 symptomatic patients with 55 long femoropopliteal occlusive lesions (52.7% TASC D lesions and 47.3% TASC C lesions) were treated. The mean target lesion length was 205±72 mm. All patients had total occlusions. The mean lesion length of the implanted Supera stents was 198±82 mm. At 12 and 24 months, the primary sustained clinical improvement rate was 80.2% and 63.6%, respectively. The Rutherford category assessment was significantly improved at 24 months compared with baseline (p=0.02). The primary patency rate at 12 and 24 months was 78.1% and 60.0%, respectively. At 12 and 24 months, freedom from TLR was 83.5% and 81.8%, respectively. There were no stent fractures at 24 months.

CONCLUSION

Supera Stent implantation for TASC C/D femoropopliteal lesions revascularization appears to be a safe and efficient implant given the complexity of the treated lesions. Head-to-head studies are mandatory to establish Supera Stent as an alternative tool to open surgery for long femoropopliteal lesions.

CLINICAL IMPACT

Our study indicated, that using self-expanding interwoven nitinol stent for TASC C/D femoropopliteal lesions revascularization appears to be a safe and efficient implant given the complexity of the treated lesions. Although bypass grafting is recommended for prolonged femoropopliteal lesions, open surgery is more traumatic and is associated with greater risks than endovascular procedures. Our findings suggest that the use of interwoven nitinol stents can overcome the disadvantages of traditional stents in such cases, which may help to improve patients' outcomes and reduce the risk of adverse events.

Bypass Versus Interwoven Nitinol Stents for Long Femoro-Popliteal Occlusions: A Propensity Matched Analysis

PURPOSE

To compare femoro-popliteal bypass and interwoven nitinol stenting for long occlusions of the femoro-popliteal segment.

MATERIALS AND METHODS

Single center retrospective propensity matching analysis of the symptomatic patients with long occlusion of the femoro-popliteal segment (> 20 cm), who underwent stenting with interwoven nitinol stent or femoro-popliteal bypass from 2012 to 2020.

PRIMARY ENDPOINTS

primary patency, primary-assisted patency, secondary patency. Secondary endpoints: major adverse cardiovascular events, major adverse limb events, primary sustained clinical improvement, survival.

RESULTS

A total of 437 patients were enrolled: 294 in the bypass group and 143 in the endovascular therapy (EVT) group. After propensity score matching, 264 and 113 patients remained in the groups, respectively. A median occlusion length was 250 mm. One-year and two-year primary and secondary patency rates were comparable in both groups (two-year primary patency: 68.5% for bypass vs. 68.9% for EVT, p = 1.00). In the "above the knee" subgroup analysis, two-year secondary patency was higher in the EVT group than in the bypass group (90.9% vs. 77.5%, p = 0.048). In "below-the-knee" subgroup analysis, primary and primary assisted patency were statistically significantly higher in the EVT group than in artificial bypass subgroup (66.7% vs. 42.4%, p = .046 and 76.7% vs. 45.5%, p = .011, respectively). However, compared to autovenous bypass, the EVT group showed lower primary patency rates, although the differences are not significant.

CONCLUSION

A nonselective endovascular strategy can allow for regular successful treatment of femoro-popliteal lesions longer than 25 cm.

Structural Aspects of Electrospun Scaffolds Intended for Prosthetics of Blood Vessels

Electrospinning is a popular method used to fabricate small-diameter vascular grafts. However, the importance of structural characteristics of the scaffold determining interaction with endothelial cells and their precursors and blood cells is still not exhaustively clear. This review discusses current research on the significance and impact of scaffold architecture (fiber characteristics, porosity, and surface roughness of material) on interactions between cells and blood with the material. In addition, data about the effects of scaffold topography on cellular behaviour (adhesion, proliferation, and migration) are necessary to improve the rational design of electrospun vascular grafts with a long-term perspective.

Understanding the Mechanism of Drug Transfer and Retention of Drug-Coated Balloons

Objective:

The purpose of this study was to determine the impact of varying inflation parameters on paclitaxel delivery and retention using a commercially available DCB.

Background:

Drug-coated balloons (DCB) have become the standard treatment for peripheral artery disease. Clinical data suggest that varying DCB delivery parameters directly impact patient outcome. Differences in delivery parameters can potentially alter the retention of the drug coating on DCBs.

Methods:

Harvested porcine carotid arteries were utilized in an ex vivo pulsatile flow bioreactor system. The DCBs were then deployed at a DCB-to-artery ratio of 1:1 or 1.25:1, an inflation time of 30 seconds or 1 minute and transit time of 30 seconds or 3 minutes. The amount of drug retention in arterial tissue was evaluated by pharmacokinetic analysis at 1 hour and 1 day post DCB deployment.

Results:

Arterial paclitaxel levels were found to be less at an inflation ratio of 1:1 with 3-minute transit time as compared to 30 seconds of transit time at 1 hour (12.3 ± 1.6 ng/mg vs. 391 ± 139 ng/mg, P = .036). At 1-day, DCBs deployed at a ratio of 1:1 resulted in less drug retention as compared to 1.25:1 (61.3 ± 23.1 ng/mg vs. 404 ± 195 ng/mg, P = .013).

Conclusion:

Arterial paclitaxel retention is reduced with extended transit times and sub-optimal expansion of the balloon. Optimization of delivery parameters can serve as an effective strategy to enhance clinical DCB outcomes.

Three-year outcome of directional atherectomy and drug coated balloon for the treatment of common femoral artery steno-occlusive lesions

BACKGROUND

Endarterectomy is considered the gold standard therapy for common femoral artery (CFA) steno-occlusive lesions, but a significant risk of perioperative mortality and complications has been reported.

OBJECTIVE

Aim of this study is to evaluate the efficacy at a long-term follow-up of patients with CFA steno-occlusive lesions treated with directional atherectomy and drug coated balloon (DCB).

MATERIAL AND METHODS

In this single-center registry, 78 patients (male: 80.7%; age: 71 ± 15 years; occlusions: 25%) with 80 CFA lesions were included, with 39.7% of them undergoing directional atherectomy and drug coated balloon due to critical limb ischemia and 60.3% due to lower-limb intermittent claudication. The long-term follow-up was completed by 75 patients (3 years). The 31 patients with critical ischemia (39.7%) were further subdivided into 20 (25.6%) patients with pain at rest and 11 (14.1%) with trophic changes, ulcers and/or tissue loss. We considered the primary and the secondary outcome, referring, respectively to peak systolic velocity ratio (PSVR) ≥ 2.4 on duplex or > 50% stenosis on digital subtraction angiography at 36 months and to clinically driven target lesion revascularization at 36 months.

RESULTS

The primary and secondary outcome was obtained in 84% and 86.7% of patients, at 36 months of follow up. Bailout stenting was necessary in 6/80 cases (7.5%) for suboptimal result. Freedom from MALE was obtained in 98.6% of patients.

CONCLUSIONS

These results confirm that directional atherectomy and drug coated balloon strategy for the treatment of CFA lesions is effective at a long-term follow-up and could be considered as a good alternative to surgery.

Finite element analysis in clinical patients with atherosclerosis

Endovascular plaque composition is strongly related to stent strut stress and is responsible for strut fatigue, stent failure, and possible in-stent restenosis. To evaluate the effect of plaque on artery wall resistance to expansion we performed in silico analysis of atherosclerotic vessels. We generated finite element models from in vivo intravascular ultrasound virtual histology images to determine local artery surface stiffness and determined which plaque structures have the greatest influence. We validated the predictive capacity of our modeling approach by testing an atherosclerotic peripheral artery ex vivo with pressure-inflation testing at physiological pressures ranging from 10 to 200 mmHg. For this purpose, the in silico deformation of the arterial wall was compared to that observed ex vivo. We found that calcification had a positive effect on surface stiffness with fibrous plaque and necrotic core having negative effects. Additionally, larger plaque structures demonstrated significantly higher average surface stiffness and calcification located nearer the lumen was also shown to increase surface stiffness. Therefore, more developed plaques will have greater resistance to expansion and higher stent strut stress, with calcification located near the lumen further increasing stress in localized areas. Thus, it may be expected that such plaque structures may increase the likelihood of localized stent strut fracture.

Microcrystalline paclitaxel-coated balloon for revascularization of femoropopliteal artery disease: Three-year outcomes of the randomized BIOPAC trial

The aim of the BIOPAC trial was to determine long-term safety and efficacy of a novel microcrystalline paclitaxel-coated balloon (mcPCB) with a biocompatible polymer as an excipient in the treatment of occlusive femoropopliteal lesions. In this first-in-human prospective controlled randomized trial, 66 patients with femoropopliteal, symptomatic (Rutherford stages 2B to 5) occlusive arterial disease were randomized to either mcPCB (study group) or POBA (plain old balloon angioplasty) (control group) on a 1:1 basis. Late lumen loss (LLL) at 6 months was the primary endpoint of the study and serious adverse events (SAE: death, amputation, repeated revascularization) were considered a composite secondary endpoint. Routine angiography was scheduled for all study subjects at 6-month follow-up; outpatient appointments were scheduled at 12 and 36 months after intervention. At 6 months, the LLL was 63% lower in the mcPCB group compared to the POBA group (0.52 ± 1.2 vs 1.39 ± 1.1 mm; psup < 0.01). Binary restenosis occurred in 23% vs 52% of patients ( p = 0.02). At 3 years, the prevalence of SAE was significantly lower in the mcPCB group (33.3 vs 63.3%; p = 0.02), which mainly resulted from a twofold reduction in target vessel revascularization rate (28.6 vs 59.3%; p = 0.02). The difference in mortality was nonsignificant (7.4 vs 14.3%; p = 0.42). Patients with mcPCB were less symptomatic and less likely to adhere to secondary prevention measures. In this pivotal trial, a novel mcPCB proved superior to POBA concerning LLL at 6-month follow-up, and SAE at 12 months. This result was sustained up to 3 years. There was no difference between groups regarding mortality. ClinicalTrials.gov Identifier: NCT02145065

The Impact of Aortic Valvular Calcium on Transcatheter Heart Valve Distortion

Objectives

To investigate the relationship between the eccentric calcification of aortic valve and transcatheter heart valve (THV) distortion and the impact of THV distortion on echo parameters and clinical outcomes.

Background

The effects of eccentric calcification of the aortic valve on the THV distortion and the relationship between THV distortion and clinical impact were not fully understood.

Methods

Patients with symptomatic severe aortic stenosis who were undergoing THV implantation were enrolled. Patients underwent preprocedural, postprocedural multislice computed tomography (MSCT), and follow-up transthoracic echocardiogram (TTE). Delta calcium score (ΔCS) is defined as the difference between the maximum and minimal calcium scores of the three cusps, while valve distortion score (VDS) is defined as the difference between the longest and shortest stent frame, as obtained using MSCT. Patients were divided into two groups according to ΔCS: “noneccentric calcification group” and “eccentric calcification group.”

Results

A total of 118 patients were enrolled (59 patients in noneccentric and 59 in eccentric calcification groups). VDS was significantly lower in the noneccentric calcification group than in the eccentric calcification group (1.31 ± 0.82 mm vs. 1.73 ± 0.76 mm, p=0.004). VDS was not associated with the degree of paravalvular leak (PVL) and aortic valvular mean pressure gradient (AVPG) at 30-day and 1-year follow-up TTE and the cumulative rates of all-cause death and rehospitalization at 2-year clinical follow-up.

Conclusions

Eccentric valvular calcification was associated with longitudinal THV distortion. However, THV distortion was not associated with PVL, AVPG, and adverse clinical events during midterm follow-up.

Pre-Clinical Investigation of Liquid Paclitaxel for Local Drug Delivery: A Pilot Study

The purpose of this pilot study was to investigate the feasibility of a perfusion catheter to deliver liquid paclitaxel into arterial segments. A clinically relevant rabbit ilio-femoral injury model was utilized to determine the impact of liquid paclitaxel delivered locally into the vessel wall using a perfusion catheter at 1 h to 14 days. Treatment by two clinically available forms of liquid paclitaxel, a solvent-based (sb) versus an albumin-bound (nab), along with a control (uncoated balloons), were investigated. Pharmacokinetic results demonstrated an increase in the retention of the sb-paclitaxel versus the nab-paclitaxel at 1 h; however, no other differences were observed at days one, three, and seven. Histological findings at 14 days showed significantly less neointimal area in the sb-paclitaxel treated arteries as compared with the nab-paclitaxel and the uncoated balloon-treated arteries. Additionally, percent area stenosis was significantly less in the sb-paclitaxel group. These results support the concept of local liquid delivery of paclitaxel into the arterial segments.

Stents in the femoropopliteal territory: prevalence of fractures and their consequences

OBJECTIVE

Endovascular treatment for femoropopliteal arterial disease has made revascularization procedures less invasive, but the self-expanding stents used can suffer great wear in arteries with extreme mobility. To evaluate the prevalence of fractures in stents implanted in the femoropopliteal segment, to identify predisposing factors and consequences on arterial patency.

METHOD

between March and June 2019, thirty patients previously operated for femoropopliteal obstruction underwent stent X-rays in anteroposterior and lateral views to detect fractures and Doppler to analyze arterial patency.

RESULTS

we observed 12 cases with fractures (33.3%): 1 type I (2.8%), 3 type II (8.3%), 5 type III (13.9%), 3 type IV (8.3%) and no type V. According to the TASC II we had 1 in group B (8.3%), 6 in group C (50%) and 5 in group D (41.6%) p <0.004. The number of stents per limb was 3.1 (± 1.3) in cases of fracture versus 2.3 (± 1.3) in cases without fracture (p = 0.08). The extension was 274.17mm (± 100.94) in cases of fracture and 230.83mm (± 135.44) in cases without fracture (p = 0.29). On Doppler we had: 17 patients (47.2%) without stenosis, 9 patients (25%) with stenosis> 50% and 10 patients (27.8%) with occlusion (p = 0.37). There was no correlation between fracture and arterial obstruction (p = 0.33).

CONCLUSION

stent fractures are a frequent finding in the femoropopliteal area (33.3%), being more prevalent in cases of more advanced disease (C and D). There was no association between the finding of fracture and arterial obstruction.

Middle and Distal Common Carotid Artery Stenting: Long-Term Patency Rates and Risk Factors for In-Stent Restenosis

PURPOSE

In the absence of literature data, we aimed to determine the long-term patency rates of middle/distal common carotid artery (CCA) stenting and to investigate predisposing factors in the development of in-stent restenosis (ISR).

MATERIALS AND METHODS

Fifty-one patients (30 males, median age 63.5 years), who underwent stenting with 51 self-expandable stents for significant (≥ 60%) stenosis of the middle/distal CCA, were analyzed retrospectively. Patient (atherosclerotic risk factors, comorbidities, medications), vessel (elongation), lesion (stenosis grade, length, calcification, location), and stent characteristics (material, diameter, length, fracture) were examined. Duplex ultrasonography was used to monitor stent patency. The Mann-Whitney U and Fisher's exact tests, Kaplan-Meier analyses, and a log-rank test were used statistically.

RESULTS

The median follow-up time was 35 months (interquartile range, 20-102 months). Significant (≥ 70%) ISR developed in 14 patients (27.5%; stenosis, N = 10; entire CCA occlusion, N = 4). Primary patency rates were 98%, 92%, 83%, 73%, and 61% at 6, 12, 24, 60, and 96 months, respectively. Reintervention was performed in six patients (11.8%) with nonocclusive ISR. Secondary patency rates were 100% at 6 and 12 months and 96% at 24, 60, and 96 months. In-stent restenosis developed more frequently (P < .001) in patients with hyperlipidemia; primary patency rates were also significantly worse (Chi-square, 11.08; degrees of freedom, 1; P < .001) in patients with hyperlipidemia compared to those without.

CONCLUSION

Stenting of the middle/distal CCA can be performed with acceptable patency rates. If intervention is unequivocally needed, patients with hyperlipidemia will require closer follow-up care.

LEVEL OF EVIDENCE

Level 3, Local non-random sample.

Paclitaxel-coated balloons in peripheral artery disease: how much is enough?

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Pseudo-aneurysm caused by stent fracture in the "sub-acute" phase after endovascular therapy for in-stent restenosis lesions

Despite the reported favorable patency of stents in the treatment of femoropopliteal lesions, concern regarding stent fracture is increasing. Development of pseudo-aneurysm by stent fracture is rare and has been reported to occur in the chronic phase owing to mechanical fatigue. Here, we present the first report of a pseudo-aneurysm caused by stent fracture in the "sub-acute" phase after endovascular therapy for in-stent restenosis lesion. A 79-year-old man underwent endovascular therapy for an in-stent restenosis lesion of the right superficial femoral artery. Echography 48 days after the treatment showed a saccular pseudo-aneurysm at the proximal stent site, suggestive of stent fracture. Angiography confirmed the pseudo-aneurysm caused by stent fracture. A self-expandable endoluminal stent graft was deployed, which showed complete resolution of the pseudo-aneurysm. A pseudo-aneurysm caused by stent fracture can occur in the "sub-acute" phase after endovascular therapy for in-stent restenosis lesions. <Learning objective: Although rare, a pseudo-aneurysm owing to stent fracture can occur in the "sub-acute" phase after endovascular therapy for in-stent restenosis lesions.>.

Outcome benefit of arterial duplex stent imaging after superficial femoral artery stent implantation

OBJECTIVE

In-stent stenosis is a frequent complication of superficial femoral artery (SFA) endovascular intervention and can lead to stent occlusion or symptom recurrence. Arterial duplex stent imaging (ADSI) can be used in the surveillance for recurrent stenosis; however, its uniform application is controversial. In this study, we aimed to determine, in patients undergoing SFA stent implantation, whether surveillance with ADSI yielded a better outcome than in those with only ankle-brachial index (ABI) follow-up.

METHODS

We performed a retrospective analysis of all patients undergoing SFA stent implantation for occlusive disease at a tertiary care referral center between 2009 and 2016. The patients were divided into those with ADSI and those with ABI follow-up only. Life-table analysis comparing stent patency, major adverse limb events (MALEs), limb salvage, and mortality between groups was performed.

RESULTS

There were 248 patients with SFA stent implantation included, 160 in the ADSI group and 88 in the ABI group. Groups were homogeneous in clinical indications of claudication and critical limb-threatening ischemia (for ADSI, 39% and 61%; for ABI, 38% and 62%; P = .982) and TransAtlantic Inter-Society Consensus class A, B, C, and D lesions (for ADSI, 17%, 45%, 16%, and 22%; for ABI, 21%, 43%, 16%, and 20%; P = .874). Primary patency was similar between groups at 12, 36, and 56 months (ADSI, 65%, 43%, and 32%; ABI, 69%, 34%, and 34%; P = .770), whereas ADSI patients showed an improved assisted primary patency (84%, 68%, and 54%) vs ABI patients (76%, 38%, and 38%; P = .008) and secondary patency. There was greater freedom from MALEs in the ADSI group (91%, 76%, and 64%) vs the ABI group (79%, 46%, and 46%; P < .001) at 12, 36, and 56 months of follow-up. ADSI patients were more likely to undergo an endovascular procedure as their initial post-SFA stent implantation intervention (P = .001), whereas ABI patients were more likely to undergo an amputation (P < .001).

CONCLUSIONS

In SFA stent implantation, patients with ADSI follow-up demonstrate an advantage in assisted primary patency and secondary patency and are more likely to undergo an endovascular reintervention. These factors are likely to have effected a decrease in MALEs, indicating the benefit of a more universal adoption of post-SFA stent implantation follow-up ADSI.

The incidence and risk factors of stent fracture in patients treated for proximal common carotid artery stenosis

OBJECTIVE

Our aim was to identify the incidence of and predictors for common carotid artery (CCA) stent fractures (SFs) and to examine the effect of SFs on the development of in-stent restenosis (ISR).

METHODS

Seventy patients (37 women; median age, 60.9 years) who were stented for significant (≥60%) proximal CCA stenosis from 2006 to 2016 and revisited us to determine SF using fluoroscopy in 2018 were evaluated. Seventy stents were deployed; among them 87.1% were balloon-expandable and 12.9% were self-expandable. SFs were classified as type I (fracture of one strut), type II (fracture of multiple struts without stent deformity), type III (fracture of multiple struts with stent deformity), type IV (complete fracture of the stent without a gap), and type V (complete fracture of the stent with a gap). Duplex ultrasound examination was used for monitoring stent patency. Mann-Whitney U and Fisher's exact tests, Kaplan-Meier and logistic regression analyses, and a log-rank test and a gamma correlation analysis were applied as statistical methods.

RESULTS

The patients were followed for 75.5 months (range, 47-109 months). Significant (≥70%) ISR was observed in eight patients (11.4%). Reintervention was performed in four cases (5.7%). Twenty-seven SFs (38.6%; type I, 8; type II, 10; type III, 4; type IV, 2; and type V, 3) were found. Calcification was shown to be a significant predictor for SF (odds ratio, 13.2; 95% confidence interval, 3.9-45.1; P < .001). There was no significant difference between the fractured and the nonfractured group regarding the number of patients with ISR and reintervention (P = .701 and P = .636, respectively). Neither did the primary patency rates differ significantly (P = .372) in patients with and without SF.

CONCLUSIONS

Fractures frequently occur in a wide variety of stent devices deployed in the proximal CCA, but SFs seem to have no effect on ISR and reintervention.

Morphologic Changes of the Femoropopliteal Arterial Segment with Knee Flexion after Endovascular Therapy

Objective: The purpose of this study is to investigate morphologic changes of the femoropopliteal arterial segment (FPAS) with knee flexion after endovascular therapy (EVT).

Methods: From July 2012 to January 2015, EVT was performed on 12 limbs in 12 consecutive patients who had obliterative lesions in the FPAS. After the implantation of nitinol stents, angiography was performed with the knee in both extension and flexion to investigate morphologic changes of the FPAS.

Results: On angiography, the distal end of the implanted stent was placed at various distances (5–10 cm in two cases, 10–15 cm in nine cases, and 15–20 cm in one case) above the knee joint line with the knee in extension. In all cases, although the popliteal artery was highly bent with the knee in flexion, the FPAS morphology was highly variable. However, the most proximal bending point of the FPAS was about 10 cm above the knee joint line. In one case, the artery was occluded at the distal part of the stent 16 months later, probably due to EVT.

Conclusion: In EVT of the FPAS, it is important to consider the characteristics and position of the stent to prevent complications.

The Impact of Diabetes and Time on the Atherosclerotic Plaque and Cardiovascular Outcome in Patients Undergoing Iliofemoral Endarterectomy

OBJECTIVE

The incidence of diabetes is rapidly increasing and diabetes is associated with an increased risk of peripheral artery disease. Recent studies have shown a time dependent decline in vulnerable plaque features and secondary cardiovascular events in iliofemoral endarterectomy (IFE) patients. IFE patients with diabetes have a high risk of cardiovascular events. It is not known, however, whether vulnerable plaque features and cardiovascular events reduce over time in IFE patients with diabetes.

METHODS

Between 2003 and 2014, 691 atherosclerotic plaques were obtained by IFE, from 212 patients with and 479 patients without diabetes. Plaques were immunohistochemically stained and analysed for the presence of intraplaque haemorrhage, lipid core, calcification, collagen, smooth muscle cells, and macrophages. Patients were stratified according to their diabetic status and year of inclusion. All patients had a follow up of three years in which cardiovascular adverse events were recorded.

RESULTS

A time dependent decrease was observed in intraplaque haemorrhage, plaque lipid core, and percentage of macrophages in IFE patients with diabetes. After multivariable correction for changes in risk factors over time, intraplaque haemorrhage (64.2% [2002-2005] vs. 39.6% [2012-2014], p = .01) became significantly less prevalent. Interestingly, the percentage of severely calcified plaques remained high over time. The number of secondary events decreased over time in patients without diabetes (HR 1.80, 95% CI 1.15-2.81 (p = .010) for 2002-2005 vs. 2012-2014), but remained high and unchanged in patients with diabetes.

CONCLUSION

In patients with diabetes undergoing IFE, a time dependent stabilisation of atherosclerotic plaque features was found in line with previous observations in patients with severe atherosclerosis. The presence of severely calcified lesions remained high and unchanged. The secondary event rate remained high in patients with diabetes in contrast to a significant decrease in patients without diabetes. These findings stress the need for improvement of care in IFE patients with diabetes.

The presence of long and heavily calcified lesions predisposes for fracture in patients undergoing stenting of the first part of the subclavian artery

OBJECTIVE

To determine the prevalence and risk factors of subclavian artery stent fractures and to investigate their impact on in-stent restenosis development.

METHODS

One hundred eight patients (65 females; median age, 58.3 years [interquartile range, 53.4-65.5 years]) with steno-occlusive disease of the first part of the subclavian artery who underwent stenting (N = 108 stents; balloon-expandable, 83.3%; self-expandable, 16.7%) between 2005 and 2015 and returned for a fluoroscopic examination of the implanted stents in 2017 were included in our study. Fractures were type I (single strut fracture), type II (multiple strut fractures without deformation), type III (multiple strut fractures with deformation), type IV (multiple strut fractures with acquired transection but without gap), or type V (multiple strut fractures with acquired transection with gap in the stent body). Stent patency was monitored by duplex ultrasound imaging. The Mann-Whitney U and Fisher's exact tests; Kaplan-Meier, receiver operating characteristic, and logistic regression analyses; as well as a log-rank test were used as statistical methods.

RESULTS

The median follow-up was 73.8 months (interquartile range, 35.6-104.2 months). Thirty-eight fractures (35.2%) were detected; fractures were type I in 13, type II in 12, type III in 6, type IV in 4, and type V in 3 cases. Multivariable logistic regression analysis revealed the presence of long (≥20 mm) lesions (odds ratio, 3.3; 95% confidence interval, 1.3-8.4; P = .012) and heavy calcification (odds ratio, 4.7; 95% confidence interval, 1.7-12.7; P = .002) to be significant independent predictors of stent fracture. The primary patency rates were significantly worse (P = .035) in patients with stent fracture compared with those without stent fracture.

CONCLUSIONS

Stent fractures frequently occur. Patients with long and/or heavily calcified lesions require closer follow-up.

Endovascular Treatment of Simultaneous Iliac and Superficial Femoral Arterial Pseudoaneurysms After Stenting Procedure Complications

PURPOSE:

To report on the endovascular management of a patient affected by concomitant left common iliac artery and right superficial femoral artery (SFA) pseudoaneurysms after stent positioning.

CASE REPORT:

A 77-year-old man affected by severe lower limb atherosclerosis was previously treated with iliac and femoropopliteal Supera stenting procedures; he presented to our emergency department because of bilateral severe claudication recurrence, back pain, and right groin region swelling. Angio-computed tomography (CT) depicted 2 pseudoaneurysms of the left common iliac artery and right SFA, due to stent fracture and stent intussusception, respectively. A 2-step endovascular treatment was planned using bilaterally covered stent-grafts to exclude vascular lesions from blood flow. The devices were successfully deployed without any complication. At 1 month, angio-CT confirmed patency of the implanted stent-grafts showing complete pseudoaneurysm exclusion without leaks.

CONCLUSION:

Endovascular approach can be a valid option in the treatment of pseudoaneurysms due to stenting procedure complications.

The use of an occlusion perfusion catheter to deliver paclitaxel to the arterial wall

AIM

Nonstent drug delivery platforms have recently emerged as an alternative treatment of peripheral arterial disease. Perfusion catheters have the potential to directly deliver antiproliferative agents to the medial arterial layer to prevent restenosis. The purpose of this study was to therefore determine the effectiveness of a perfusion catheter to deliver paclitaxel, a proven antiproliferative agent, to combat restenosis.

METHODS

A benchtop model was utilized to determine the varying parameters of a novel occlusion perfusion catheter to maximize paclitaxel delivery using pharmacokinetic evaluation and fluorescent microscopy. Parameters tested included concentration of paclitaxel, delivery pressure, duration of delivery, and the use of an excipient. In addition, bilateral rabbit iliac arteries were treated with the perfusion catheter and pharmacokinetic evaluation performed at 1 hour, 1 day and 3 days.

RESULTS

Benchtop testing demonstrated uniform and circumferential penetration of paclitaxel within the treated arteries. The results of the ex vivo test identified two groups with and without an excipient with similar loading conditions (with excipient: 15.4±8.6 ng/mg vs without excipient: 8.9±6.9 ng/mg, P=.77). The in vivo pharmacokinetic analysis of these two groups demonstrated the use of contrast agent increased arterial paclitaxel levels and maintained initial paclitaxel dosing up to 3 days (With excipient: 1 hour: 107±62 ng vs 3 days: 40±23 ng, P=.824; No excipient: 1 hour: 247±120 ng vs 3 days: 2.92±2.9 ng, P=.009).

CONCLUSIONS

These results demonstrate the feasibility to deliver paclitaxel directly to the medial layer of an artery via a perfusion catheter.

Comparison of Endovascular Versus Bypass Surgery in Femoropopliteal TASC II D Lesions: A Single-Center Study

BACKGROUND

In patients with severe occlusive disease (Trans-Atlantic Inter-Society Consensus II D [TASC II D]) of the femoropopliteal segment, the advantages of endovascular versus bypass revascularization still remain debated. Most reports available in literature comparing percutaneous transluminal angioplasty (PTA) ± bare metal stent (BMS) versus synthetic bypass analyze patients with heterogeneous anatomical lesions creating possible bias when results of different treatments are matched. In this study, we compared early and midterm outcomes of PTA ± BMS versus heparin-bonded expanded polytetrafluoroethylene graft (Propaten-Gore) + Linton patch in patient affected by symptomatic femoropopliteal TASC II-D lesions.

METHODS

Eighty limbs with symptomatic severe occlusive disease (TASC II D) of the femoropopliteal segment observed from January 2013 to January 2017 were included in this retrospective study. Indication to treatment was severe claudication in 17 limbs (21.2%) and critical limb ischemia (CLI) in 63 (78.8%). 36.2% of limbs presented at least 2 distal patent vessels, and 63.8% had only 1 patent vessel. Of these limbs, 40 were treated by means of PTA ± BMS (group A), and 40 were treated by means of femoropopliteal bypass with Propaten-Gore graft + Linton patch (group B). Patients were followed with a clinical assessment and duplex at 1, 6, and 12 months after procedure and then annually. A closer follow-up was performed in case of any complication. Patency, reintervention rate, and limb salvage were compared in the 2 groups.

RESULTS

The mean length of arterial occlusion was 22.1 cm (range, 8-37) in group A versus 25.2 cm (range, 9-41) in group B, P = ns. A slight difference in mean procedural time was observed (83.5 min of group A versus 114 min of group B, minutes, P = 0.02). Mean follow-up was 26.7 months (range, 3-46). Primary patency at 6, 12, and 24 months of group A versus group B was 76.9% vs. 97.5% (P = 0.007), 65.7% vs. 89.1% (P = 0.05), and 52.6% vs. 78.1% (P = 0.005), respectively. Assisted primary patency was 76.9% vs. 97.5% (P = 0.007), 68.5% vs. 91.8% (P = 0.02), and 57.8% vs. 87.5% (P = 0.001), respectively. Secondary patency was 94.8% vs. 97.5% (P = ns), 85.7% vs. 97.2% (P = ns), 73.6% vs. 93.7% (P = 0.004), respectively. Rate of reintervention at 24 months was 45% in group A vs. 20% in group B (P = 0.03). Limb salvage rate at 24 months was 90% for group A vs. 92.5% for group B (P = ns). Univariate analysis showed CLI and poor runoff to be independent risk factors for significant restenosis/occlusion of target artery and reintervention.

CONCLUSIONS

In patients with severe femoropopliteal occlusive disease (TASC II D), the surgical revascularization by means of Propaten-Gore bypass + Linton patch can be considered safe and effective. Early and midterm results of this approach seem to be superior to PTA ± BMS in terms of restenosis/occlusion and reintervention rates. Larger cohort and longer term results are mandatory to better define this advantage.

Fractured Superior Mesenteric Artery Stent With Stent Displacement Leading to Recurrent Symptoms of Superior Mesenteric Ischemia

We report a case of a patient with recurrent symptoms of superior mesenteric ischemia 7 months after successful percutaneous angioplasty and implantation of a stent in the superior mesenteric artery (SMA). Stent fracture and stent displacement were observed. To the best of our knowledge, this is the first report of SMA stent fracture with stent displacement.

Stent placement in the superficial femoral and proximal popliteal arteries with the innova self-expanding bare metal stent system

OBJECTIVES

The SuperNOVA trial was designed to evaluate performance of the Innova Vascular Self-Expanding Stent System (Boston Scientific, Marlborough, MA) for treating lesions in the femoropopliteal arteries.

METHODS

Patients with chronic lower limb peripheral artery disease (Rutherford category 2, 3, or 4) and atherosclerotic lesions in the native superficial femoral and/or proximal popliteal artery (lengths 30-190 mm) were enrolled in this single-arm, multinational study. Major adverse events (MAEs) were defined as all-cause death through 1 month, target limb major amputation, and target lesion revascularization (TLR). Vessel primary patency was defined as core laboratory-adjudicated duplex ultrasonography-derived peak systolic velocity ratio ≤2.4 in the absence of TLR, surgical bypass of the target lesion, or major amputation of the target limb. Primary safety and efficacy endpoints were evaluated at 12 months, with follow-up through 24 months also reported.

RESULTS

SuperNOVA patients (N = 299; mean age 67.4 ± 9.7 years, 74% men, 41% with diabetes) had a mean lesion length of 93.2 mm. The MAE-free rate was 99.7% at 30 days, 85.8% at 12 months, and 77% at 24 months. Kaplan-Meier estimates of primary patency and TLR-free rates were 68.7% and 78.0%, respectively, at 24 months. Clinical improvements were sustained through 2 years, with 80% of patients displaying no or minimal symptoms (Rutherford category 0-1) at 24 months.

CONCLUSIONS

In the SuperNOVA study, the Innova Stent System demonstrated an excellent safety profile and acceptable clinical outcomes despite the challenging anatomical characteristics of the lesions. © 2017 Wiley Periodicals, Inc.

Nitinol Self-Expanding Stents for the Superficial Femoral Artery

The superficial femoral artery is a complex artery subject to a unique set of biomechanical loading conditions in its course through the leg. Plain balloon angioplasty and balloon-expandable stents had unacceptably high rates of restenosis, necessitating target vessel revascularization. Nitinol alloy is well suited to provide the strength and flexibility needed of stents to withstand the external forces posed by the environment of the superficial femoral artery. Advances in stent technology with the addition of a slow-releasing antiproliferative agent and changes in scaffold design have shown promise in reducing the rates of stent fracture and in-stent restenosis.

Dynamic Respiratory Tortuosity of the Vertebral Artery Ostium

PURPOSE

To determine the prevalence of dynamic respiratory tortuosity (DRT) of the vertebral artery ostium (VAO) as well as to evaluate its correlation with in-stent restenosis (ISR) and stent fracture.

METHODS

From March 2012 to June 2015, 178 consecutive patients (mean age 65.2±5.8 years; 124 men) with symptoms of atherosclerotic vertebrobasilar ischemia underwent angiography prior to stent implantation in the vertebral, subclavian, and/or carotid arteries. In this cohort, 54 patients (mean age 67.3±5.3 years; 40 men) had VAO stent implantation. Angiography of the vertebral artery was recorded in 2 phases with breath-hold: deep inspiration (DIP) and deep expiration (DEP). Obvious VAO tortuosity was defined as any VAO angle ≤120° in DIP. Obvious VAO-DRT was defined as any VAO angle increasing ≥60° from DIP to DEP. Computed tomography angiography (CTA) or digital subtraction angiography was used in follow-up to detect ISR and stent fracture.

RESULTS

Of the 178 patients in this study, 21 (11.8%) had obvious VAO tortuosity and 8 (4.5%) had obvious VAO-DRT. Two of the 21 patients with obvious VAO tortuosity also had obvious VAO-DRT. Three of the 54 VAO stent patients had VAO-DRT. There were no correlations between VAO-DRT and age, sex, risk factors, body mass index, chronic obstructive pulmonary disease, asthma, or obvious VAO tortuosity (p>0.05). Over a mean follow-up of 28±10 months, there were 4 (7.4%) asymptomatic VAO ISR cases. Two (3.7%) were occlusions at 6 and 12 months, respectively; both were associated with stent fracture in patients with obvious VAO-DRT before stenting. Both stents fractured at the tortuous VAO region. VAO-DRT was correlated with stent fracture (Spearman ρ=0.81, p<0.01) and ISR (Spearman ρ=0.55, p<0.01).

CONCLUSION

VAO-DRT could be a risk factor for stent fracture and restenosis after VAO stent implantation. Angiography in both inspiration and expiration phases, especially the latter, should be considered before VAO stenting. Using a shorter stent to avoid crossing the tortuosity could reduce the occurrence of fracture.

Key Concepts in Critical Limb Ischemia: Selected Proceedings from the 2015 Vascular Interventional Advances Meeting

Over 500,000 patients each year are diagnosed with critical limb ischemia (CLI), the most severe form of peripheral artery disease. CLI portends a grim prognosis; half the patients die from a cardiovascular cause within 5 years, a rate that is 5 times higher than a matched population without CLI. In 2014, the Centers for Medicare and Medicaid Services paid approximately $3.6 billion for claims submitted by hospitals for inpatient and outpatient care delivered to patients with CLI. Although significant advances in diagnosis, treatment, and follow-up of patients with CLI have been made, many challenges remain. In this article, we summarize selected presentations from the 2015 Vascular Interventional Advances Conference related to the modern demographics, diagnosis, and management of patients with CLI.

Fatigue of Metallic Stents: From Clinical Evidence to Computational Analysis

The great success of stents in treating cardiovascular disease is actually undermined by their long-term fatigue failure. The high variability of stent failure incidence suggests that it is due to several correlated aspects, such as loading conditions, material properties, component design, surgical procedure, and patient functional anatomy. Numerical and experimental non-clinical assessments are included in the recommendations and requirements of several regulatory bodies and they are thus exploited in the analysis of stent fatigue performance. Optimization-based simulation methodologies have been developed as well, to improve the fatigue endurance of novel designs. This paper presents a review on the fatigue issue in metallic stents, starting from a description of clinical evidence about stent fracture up to the analysis of computational approaches available from the literature. The reported discussion on both the experimental and numerical framework aims at providing a general insight into stent lifetime prediction as well as at understanding the factors which affect stent fatigue performance for the design of novel components.