Multi-Link Stent Research Articles

Electrochemical polishing, characterisation and in vitro evaluation of additively manufactured CoCr stents with personalised designs

Additive manufacturing (AM) technology has paved the way for manufacturing personalised stents. However, there is a notable gap in comprehensive microstructure analyses and in vitro evaluations of the AM CoCr stents using advanced methodologies. To address this gap, this study focuses on investigating the microstructure and in vitro performance of personalised CoCr stents manufactured through micro-laser powder bed fusion (μ-LPBF). The evaluation process begins with the measurements of dimensions and surface roughness, followed by in-depth microstructural analyses. To improve surface roughness and reduce excessive strut size, the μ-LPBF stents undergo electrochemical polishing. Importantly, in vitro stent deployments are carried out in artificial arteries manufactured based on actual patients' data. Compared to the commercial MULTI-LINK VISION CoCr stent, the μ-LPBF personalised stents have rough surface finish (average roughness: 1.55 μm for μ-LPBF vs. 1.09 μm for commercial) and compromised grain microstructures (elongated for μ-LPBF vs. equiaxed for commercial). However, the personalised stents demonstrate better performances in in vitro tests. Notably, compared to the commercial stent in the two studied cases, they deliver larger lumen gains (up to 11.24 %) and reduced recoils (up to 4 times). This study validates the merit of the lesion-specific designs and the feasibility of using AM technology for stent fabrication.

In silico evaluation of additively manufactured 316L stainless steel stent in a patient-specific coronary artery

Additive manufacturing (AM) is an emerging method for the fabrication of stents, which is cost-saving and capable of producing personalised stent designs. However, poor surface finish and dimension discrepancy in the manufactured stents can significantly affect not only their own mechanical behavior but also mechanical response of arteries. This study investigates the effects of surface irregularities and dimension discrepancy of a 316L stainless steel stent, manufactured using laser powder bed fusion (LPBF), on its biomechanical performance, in comparison with the original design and a commercial stent. In silico simulations of stent deployment in a patient-specific coronary artery, based on intravital optical coherency tomography imaging, are conducted to assess the stent deformation as well as arterial stress and damage. Severe plastic strain concentrations (with a maximum value of 1.93) occur in the LPBF stent after deployment due to surface irregularities, suggesting a high risk of stent fracture. The LPBF stent is harder to expand due to its thicker struts and closed-cell design (diameter of 4.14 mm at the peak inflating pressure during deployment, compared to 4.58 mm and 4.65 mm for the designed and MULTI-LINK RX ULTRA stents, respectively). Also, the LPBF stent induces a higher level of stress concentration (with a maximum value of 23.04 MPa) to the arterial layers, suggesting a higher risk of tissue damage and in-stent restenosis. This study demonstrates a clear need for further development of the AM process for manufacturing medical implants, especially the surface finish and dimension accuracy.

Experience of stent implantation for recurrent aortic arch obstruction following Norwood or Damus–Kaye–Stansel operation over the last decade

Recurrent aortic arch obstruction following the Norwood procedure is recognised as an important complication. Balloon arch angioplasty is associated with a high recoarctation rate. We sought to evaluate the prevalence and outcome of stent implantation for recoarctation in children following Norwood or Damus-Kaye-Stansel procedure over the past decade at a single national cardiology centre. Of 114 children who underwent Norwood procedure or Damus-Kaye-Stansel procedure between January 2003 and June 2013, 80 patients survived. Of these 15 children underwent stent implantation for recoarctation. Six of these patients had previous balloon angioplasty. The median age at stent implantation was 4.4 months (range 2-82 months). The median peak aortic arch gradient at catheterisation decreased from 26mmHg (range 10-70mmHg) to 2mmHg (range 0-20mmHg). The median luminal diameter increased from 4.7 mm (range 3.2-7.9 mm) to 8.6 mm (range 6.2-10.9 mm). The median coarctation index increased by 0.49 (range = 0.24-0.64). A Valeo stent was employed in 11 children, a Palmaz Genesis stent in 2 patients, a MultiLink stent in 1 child, and a Jomed covered stent in 1 child. Two factors were associated with the need for stent placement: previous arch angioplasty (p valve < 0.001, χ-square 11.5) and borderline left ventricle (p = 0.04, χ-square = 4.1). Stent migration occurred in one child. There were two deaths related to poor right ventricular systolic function and severe tricuspid regurgitation. Six patients underwent redilation of the stent with no complications. The prevalence of recurrent aortic arch obstruction following Norwood/Damus-Kaye-Stansel procedure was 18%. Stent implantation is safe and reliably eliminates the aortic obstruction. Redilation can be successfully achieved to accommodate somatic growth or development of stent recoarctation.

Application of finite element method to comparing the NIR stent with the multi-link stent for narrowings in coronary arteries

‘Stent versus stent’ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulatory agencies, such as the U.S. Food and Drug Administration (FDA), to give an approval to new stent designs. The problem with these clinical trials is their high cost and difficulty. In this paper, a numerical alternative for ‘stent versus stent’ complicated clinical studies is presented. A finite element model is developed to investigate the influence of stent design on the outcome after coronary stent placement. Two commercially available stents (the NIR and Multi-Link stents) are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and foreshortening. Moreover, the effect of stent design on the restenosis rate is investigated by comparing the stress distribution within the arteries. An analysis of the arterial wall stresses in the stented arteries indicates that the Multi-Link stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. The findings correlate with the observed clinical restenosis rates, which have reported higher restenosis rates in the NIR compared with the Multi-Link stent design.

Abstract 16008: Improved Safety and Efficacy of a Novel Dual cRGD- and Everolimus-Coated Coronary Stent Compared to Everolimus-Eluting Stents in the Porcine Coronary Model

Background: Re-endothelialization after drug-eluting stent implantation is delayed. Integrin-binding cyclic Arg-Gly-As p (cRGD) peptide-loaded stents offer potential for enhanced early and late endothelial recovery by endothelial progenitor cell (EPC) anchorage. Here, a novel dual cRGD and everolimus-eluting stent was compared to an everolimus-eluting stent. Methods: The porcine coronary overstretch model was employed for analysis of Multi-Link Tetra bare metal stents with or without a specific conformal, mechanically robust polymer coating based on an aromatic polyetherurethaneurea with a soft segment of polytetramethyleneoxide and a hard segment of diphenylmethane diisocyanate and mixed diamines covered by a control-release layer. Stents were coated with immobilized cRGD, everolimus or cRGD+everolimus on the biostable PEA-40 polymer surface coating. Isolated porcine EPCs were labeled with cell tracker and infused into coronary arteries immediately after stent implantation. cRGD or everolimus recovered mass was quantified, re-endothelialization was assessed by scanning electron microscopy and area stenosis was quantified. Results: cRGD and everolimus recovered mass from PEA-40 cRGD/everolimus stents possessed a slow release profile. Marked EPC recruitment to stents was evidenced after intracoronary infusion of fluorescence-labeled EPCs. In cRGD+everolimus loaded stents, in-stent cross sectional stenosis was reduced and re-endothelialization above stent struts was accelerated (p&lt;0.05 for both) while re-endothelialization between struts was similar (p&gt;0.05) as compared to both everolimus-loaded and bare-metal stents. Conclusions: PEA-40 is a reliable carrier for cRGD and everolimus; the novel PEA-40 dual cRGD and everolimus stent coating both everolimus-dependently decreases coronary stenosis as well as integrin-dependently accelerates stent strut re-endothelialization as compared to everolimus-eluting stents in the porcine coronary overstretch model. Therefore, the concerted acceleration of vascular healing by facilitated homing of circulating EPCs and distinct antiproliferatory properties of everolimus might transfer to an improvement of stent safety while stent efficacy is maintained.

Analysis of the stent expansion in a stenosed artery using finite element method: application to stent versus stent study.

In this article, finite element method is used to investigate the mechanical behavior of a stent and to determine the biomechanical interaction between the stent and the artery in a stenting procedure. The main objective of this study is to reach to a model close to a real condition of coronary stent placement. Unlike most of the models proposed in the literature, all the steps of the deployment of a stent in the stenotic vessel (i.e. pressure increasing, constant load pressure and pressure decreasing) are simulated in this article to show the behavior of the stent in different stages of implantation. The results indicate that the first step of deployment, that is, pressure increasing, plays a main role in the success of stent implantation. So that, in order to compare the behavior of different types of stents, it is sufficient to compare their behavior at the end of pressure increasing step. In order to show the application of the findings in stent versus stent studies, three commercially available stents (the Palmaz-Schatz, Multi-Link and NIR stents) are modeled and their behavior is compared at the end of pressure increasing step. The effect of stent design on the restenosis rate is investigated. According to the findings, the possibility of restenosis is lower for Multi-Link and NIR stents in comparison with Palmaz-Schatz stent which is in good agreement with clinical results. Therefore, the testing methodology outlined here is proposed as a simple and economical alternative for "stent versus stent" complicated clinical trials.

A Randomized Comparison between Everolimus-Eluting Stent and Cobalt Chromium Stent in Patients with Acute ST-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention Using Routine Intravenous Eptifibatide: The X-MAN (Xience vs. Multi-Link Stent in Acute Myocardial Infarction) Trial, A Pilot Study.

The objective of this study is to determine the efficacy and safety of an everolimus-eluting stent (EES/Xience; Abbott Vascular, Santa Clara, CA) compared with a cobalt chromium stent (CoCr/Multi-Link Vision; Abbott Vascular) in patients with acute ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) with routine administration of eptifibatide infusion. This is a prospective, single center, randomized trial comparing EES (n = 75) and CoCr stent (n = 75) implantation in patients with acute STEMI undergoing primary PCI. Intravenous eptifibatide administration was mandatory by protocol in this pilot study. The primary efficacy endpoint was major adverse cardiac events (MACE) at 30 days, defined as the composite of death, reinfarction, and target vessel revascularization. Secondary safety endpoints were stent thrombosis at 30 days and in-hospital bleeding event. Acute reperfusion parameters were also assessed. One-month MACE rate did not differ between EES and CoCr group (1.3 vs. 1.3%, p = 1.0). No stent thrombosis cases were observed in the EES group. The groups did not differ with respect to in-hospital bleeding events (5 vs. 9%, p = 0.37), achievement of final thrombolysis in myocardial infarction flow 2 or 3 (p = 0.21), achievement of myocardial blush grade 2 or 3 (p = 0.45), creatine kinase-MB level at 8 to 12 hours after stenting (p = 0.29), and left ventricular ejection fraction (p = 0.21). This pilot study demonstrates that after one-month follow-up, the use of EES is as safe and effective as the use of CoCr stents in patients with acute STEMI undergoing primary PCI with routine administration of intravenous eptifibatide.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Randomized Comparison of Xience V and Multi-Link Vision Coronary Stents in the Same Multivessel Patient With Chronic Kidney Disease (RENAL-DES) Study

Percutaneous coronary interventions in patients with chronic kidney disease have shown suboptimal results. Drug-eluting stents (DES) might reduce the rate of target vessel revascularization in comparison with bare-metal stents (BMS) in patients with chronic kidney disease. However, given the multiple concomitant individual variables present in such patients, the comparison of neointimal growth after percutaneous coronary intervention is complex and difficult to assess. Randomized Comparison of Xience V and Multi-Link Vision Coronary Stents in the Same Multivessel Patient with Chronic Kidney Disease (RENAL-DES) was a prospective, randomized, multicenter study to directly compare the efficacy in the prevention of clinical restenosis of everolimus-eluting stent (Xience V) and BMS with an identical design (Multi-Link Vision), both implanted in the same patient with multivessel coronary artery disease and chronic kidney disease (estimated glomerular filtration rate <60 mL/min). The primary end point of the study was the ischemia-driven target vessel revascularization as detected with myocardial scintigraphy at 12 months. In 215 patients, 512 coronary vessels were successfully treated with the randomly assigned DES (n=257) or BMS (n=255). At 1 year, the rate of ischemia-driven target vessel revascularization for DES and BMS groups was 2.7% (95% confidence interval, 1.1%-5.6%) and 11.4% (95% confidence interval, 7.8% to 16%), respectively, P<0.001. For the multivariate analysis, independent predictors of the ischemia-driven target vessel revascularization were BMS implantation (odds ratio, 4.95; 95% confidence interval, 2.1-11.6; P<0.001) and vessel size (odds ratio, 0.32; 95% confidence interval, 0.1-0.7; P=0.006). This is the first randomized trial showing a reduction of clinical restenosis with a new-generation DES in comparison with a BMS of equal design, in patients who have chronic kidney disease with multivessel coronary artery disease. http://clinicaltrials.gov. Unique identifier: NCT00818792.

Can Start-Ups Finish Up?

In this issue of Circulation: Cardiovascular Quality and Outcomes , Xu et al present findings from a search of US patents related to bare-metal coronary stents in an effort to gain insight on how medical device innovation starts and how policies in the United States might help to promote more innovation.1 Of the 245 patents identified by their search strategy for the years 1984 to 1994, the authors report that the most frequently cited stent patents (their measure of patent importance to innovation headlined by the Palmaz and Gianturco patents) were from individual physician inventors working in academic medical centers and their small private companies. They also report a temporal trend that shows, in later years, more patents were granted to public companies. They concluded that policies aimed at supporting these entities might enhance and accelerate innovation because early innovation, in this case, was spurred by individual inventors with their small companies. Article see p 743 It is true that individual practitioners struggling with the challenges of everyday practice are an important source of new-device concepts that can possibly solve an unmet clinical need. However, the journey of successful innovation to maximized impact on public health requires that these early ideas (such as the original stiff, boxcar like tubular stent of Palmaz or the poorly scaffolding clam shell stent of Gianturco) need significant refinement through subsequent innovation (such as the later, industry-based Lau patent of the Multilink stent that …

The Appraisal-Trial: Evaluating RESTEN-MPTM in Patients with Bare Metal Stent De Novo Native Coronary Artery Lesions

Neointimal hyperplasia is one of the key components of the restenotic process. The aim of this study was to evaluate the efficacy and safety of a microbubble delivery of c-myc antisense peptide in reducing restenosis after coronary stenting in de novo stenosis with intravascular ultrasound. A Multi-Link Zeta bare metal stent was implanted in de novo coronary artery lesions (RD ≥ 2.5- ≤ 4.0 mm; TL ≥ 15- ≤ 30 mm in length). Serial intravascular ultrasound analyses were performed in 25 lesions. A dose of 16mg RESTEN-MPTM (AVI BioPharma supplied by Global Therapeutics LLC) was intravenously administered after stenting and again 24 hours later. In three centres in Germany a total of 50patients (51 lesions) were enrolled, 34 in Essen, 13 in Coburg and 3 in Heidelberg. Before stenting, the minimal lumen diameter (MLD) and length of stenosis were determined. 84% (43/51) of the lesions were either Type B2 or C lesions. At six-month follow-up, angiography was performed. Generally the neointimal proliferation was minor. Major adverse cardiac events (MACE) were 10.0% after 6 months and 21.9% after 12 months. The target lesion revascularization was 15.6%, the target vessel revascularization 18.8% after 12 months. Of the 34 patients studied at six-months in the IVUS sub-study, six patients required target lesion revascularization (TLR). Binary restenosis rate by intravascular ultrasound was 26 ± 4%. Generally the neointima proliferation was minor and open vessel lumen could be demonstrated during follow-up. Microbubble delivery of c-myc antisense seems to be effective in reducing neointimal tissue proliferation without the problem of late stent thrombosis. Neointima proliferation seems to be attenuated but not eliminated. MACE was not increased in this study population.

Long-Term Clinical Outcome of Thin-Strut Cobalt-Chromium Stents in the Drug-Eluting Stent Era: Results of the COBALT (Comparison of Bare-Metal Stents in All-Comers’ Lesion Treatment) Registry

Despite widespread penetration of drug-eluting stents (DES) in clinical practice, a relevant percentage of patients with coronary artery disease are still treated with bare-metal stents (BMS). Contemporary BMS, however, are less well investigated and comparative data on clinical outcome are lacking. This single-center registry aimed to assess characteristics and outcome of patients treated with 2 different new-generation cobalt-chromium BMS, the MULTI-LINK VISION and PRO-Kinetic stents. During the study, adopted criteria for BMS selection were: (1) limited compliance to dual antiplatelet therapy, (2) ST-elevation myocardial infarction (MI) or saphenous vein graft (SVG) interventions, and (3) noncomplex lesions located either in the right coronary artery or in the nonproximal segments of the left coronary artery. During a 24-month period 1,176 patients were treated with the VISION (n = 438) or PRO-Kinetic stent (n = 738). Median duration of follow-up was 549.5 and 528.5 days, respectively. Target lesion revascularization (TLR) and target vessel revascularization were numerically lower in the VISION group (10.4 vs. 12.3% and 11.9 vs. 15.2%, P = 0.24 and 0.11). Death (4.1 vs. 4.3%, P = 0.85), MI (2 vs. 2.3%, P = 0.78), and ARC definite stent thrombosis (0.5 vs. 0.5%, P = 0.84) were similar. By multivariate analysis, variables associated with TLR were SVG interventions (HR 2.21, 95% CI 1.26-3.86), total stent length (HR 1.01, 95% CI 1.00-1.02), and smoking (HR 1.51, 95% CI 1.05-2.16). In the DES era, the use of last-generation thin-strut BMS in selected patients is associated with acceptable clinical outcome, with similar clinical results for both the MULTI-LINK VISION and PRO-Kinetic stents.

Multi-Link Vision stent vs. first-generation drug-eluting stents: systematic review and meta-analysis

Since its introduction, the cobalt chromium alloy MULTI-LINK VISION stent (MLV) has been extensively investigated thus leading to the largest amount of data so far available for a bare metal stent. Aim and Systematic review and meta-analysis (according to Cochrane collaboration guidelines) aiming at summarizing the real world safety and efficacy of MLV stent. Endpoints of interest were: major adverse events [(MAE) combination of overall death and non-fatal myocardial infarction, MI], and target vessel revascularization (TVR). Rate of stent thrombosis was also assessed. Eleven studies finally retrieved totalling 5539 patients [7 study registries, 4243 patients and 4 randomized controlled trials (RCTs) comparing MLV vs. first generation of drug-eluting stent (DES) (paclitaxel or sirolimus eluting), (RCTs) 1296 patients]. Across study registries, at a mean follow-up of 11.1 months, MLV was associated with a 5.3% risk of MAE, 3% of death, 2.3% of MI and a 9% of TVR. Risk of ST was 0.5%. Compared to first generation of DES in RCTs, at a mean follow-up of 10.5 months, MLV achieved similar results in terms of MAE, death and MI. On the other hand, MLV was associated with a double risk of TVR [OR 2.01 (1.34-3.01), P < 0.001, number needed to treat 18 (13-40)]. Overall, in stent late loss with MLV was 0.81 mm (±0.51), while the in segment late loss was 0.61 mm (±0.5). Risk of stent thrombosis was equivalent. Of note, performance of MLV in terms of safety, efficacy and risk of repeat revascularization was quite consistent across all the published studies, despite inherent differences in study design, clinical setting, complexity of the lesions and ethnicity. Compared to first-generation DES, MLV showed substantial equivalence with respect to hard clinical endpoints. Data are consistent in study registries and RCTs meaning that the overall performance of MLV is quite predictable and reproducible into the wide spectrum of clinical settings.

AS-111: Early and Long-Term Outcomes of MULTI-LINK VISION Stent

Drug-eluting stents (DES) have been the major choice for treating patients with coronary artery disease in recent years because they can significantly decrease in-stent restenosis. However, the stent thrombosis of DES has attracted attention of cardiologists, and accompanying long-term antiplatelet therapy is not suitable for some patients who are likely to bleed. Thus, bare metal stents (BMS) still play an important role in percutaneous coronary intervention in the DES era. We evaluated the early and long-term outcomes of one of the most popular high-performance BMS, the MULTI-LINK VISION stent (cobalt-chromium coronary stent), in our hospital.

The Drug-Eluting Stent Saga

Drug-eluting stents (DES) represent a breakthrough technology owing to their potent reduction of restenosis, which is a nuisance in the quality of life of affected patients, a rare cause of myocardial infarction (MI), and the principal shortcoming of stents compared with coronary artery bypass surgery. First-generation DES with controlled release of sirolimus or paclitaxel from durable polymers reduce the need of target lesion revascularization by 50 to 70% compared with bare metal stents, requiring treatment of only 8 patients (number needed to treat 6 to 10) to prevent 1 revascularization event.1 The benefit, albeit attenuated, persists in studies without protocol-mandated angiographic follow-up,2 is particularly pronounced in diabetic patients,3 and endures during long-term follow-up extending to 5 years.1 The safety of first-generation DES has been scrutinized in unprecedented depth and comprehensiveness after insinuation of impaired clinical outcome. Even though mortality and MI were found to be similar or even lower with the use of first-generation DES in randomized trials, meta-analyses, and large-scale registries,4 very late stent thrombosis (ie, sudden thrombotic occlusion of the device >1 year after implantation) emerged as a distinct entity complicating their use.5 Article p 680 Later-generation DES have been developed with the objective to improve clinical outcomes by providing better deliverability and optimized long-term biocompatibility of polymer coatings and by introducing new antiproliferative drugs. One of these new DES is the everolimus-eluting stent (Abbott Vascular, Santa Clara, Calif), recently approved by the US Food and Drug Administration for percutaneous coronary interventions.6,7 The underlying stent platform is the Multilink Vision stent made of L-605 cobalt chromium alloy with an open cell nonlinear link design and the lowest strut thickness (81 μm) currently available with DES. Everolimus is a sirolimus derivative in which the hydroxyl at position C40 of sirolimus has been …

Automated generation of a finite element stent model

Numerical simulations have proven to be a valuable tool to investigate the mechanical behavior of stents. These computer models require a considerable amount of preprocessing and computational effort and consequently there is a continuous need for accurate simplifications and automation. For example, it was recently shown that using beam elements instead of solid elements results in a significant speed up of stent simulations. However, the currently applied techniques to create a finite element mesh starting from stent samples remain time-consuming. We present a semi-automated strategy to obtain an accurate finite element beam mesh from a stent sample. The method consists of two steps: (1) A triangulated surface representation of the stent geometry is obtained from micro CT images. (2) Subsequently, a beam mesh is automatically generated by computing the centerline. The method is time-effective and results in an accurate 3D stent model as demonstrated for the MULTI-LINK Vision stent.

In-vitro evaluation of coronary stents and 64-detector-row computed tomography using a newly developed model of coronary artery stenosis

Stent implantation is the predominant therapy for non-surgical myocardial revascularization in patients with coronary artery disease. However, despite substantial advances in multidetector computed tomography (MDCT) coronary imaging, a reliable detection of coronary in-stent restenosis is currently not possible. To examine the ability of 64-detector-row CT to detect and to grade in-stent stenosis in coronary stents using a newly developed ex-vivo vessel phantom with a realistic CT density pattern, artificial stenosis, and a thorax phantom. Four different stents (Liberté and Lunar ROX, Boston Scientific; Driver, Medtronic; Multi-Link Vision, Guidant) were examined. The stents were placed on a polymer tube with a diameter of 2.5, 3.0, 3.5, or 4.0 mm. Different degrees of stenosis (0%, 30%, 50%, 70-80%) were created inside the tube. For quantitative analysis, attenuation values were measured in the non-stenotic vessel outside the stent, in the non-stenotic vessel inside the stent, and in the stenotic area inside the stent. The grade of stenosis was visually assessed by two observers. All stents led to artificial reduction of attenuation, the least degree of which was found in the Liberté stent (11.3+/-10.2 HU) and the Multi-Link Vision stent (17.6+/-17.9 HU; P = 0.25). Overall, the non-stenotic vessel was correctly diagnosed in 55.5%, the low-grade stenosis in 58.3%, the intermediate stenosis in 63.8%, and the high-grade stenosis in 80.5%. In the 3.0-, 3.5-, and 4.0-mm vessels, in none of the cases was a non-stenotic or low-grade stenotic vessel misdiagnosed as intermediate or high-grade stenosis. The average deviation from the real grade of stenosis was 0.40 for the Liberté stent, 0.46 for the Lunar ROX stent, 0.45 for the Driver stent, and 0.58 for the Multi-Link Vision stent. Our ex-vivo data show that non-stenotic stents and low-grade in-stent stenosis can be reliably differentiated from intermediate and high-grade in-stent stenosis in vessels with a diameter of 3 to 4 mm. With regard to artifacts and the grading of stenoses, the Liberté stent was best suited for CT coronary angiography.

Infragenicular angioplasty and stenting in the management of critical limb ischaemia: one year outcome following the use of the MULTI-LINK VISION stent

Use of stents following angioplasty for infragenicular lesions appears to be superior to angioplasty alone. We investigated the safety and efficacy of MULTI-LINK VISION stent (Abbott Vascular, Brussels, Belgium) for the treatment of infragenicular lesions in patients with critical limb ischaemia (CLI). During the period between February 2005 and October 2005, fifty patients with CLI (Rutherford 4 and 5) due to infragenicular disease were included in the study. The studied patient population included 28 males (56.0%) and 22 females (44.0%) with a mean age of 76 years (range 59-90 years). The medical history was significant for hypertension in 43 patients (86.0%), diabetes in 23 (46%) and hypercholesterolaemia in 37 (74%) patients. Fourteen patients (28%) admitted to the use of nicotine. Thirty-four (68%) belonged to Rutherford class 4 and 16 were class 5 (32%). All patients underwent clinical evaluation before and after the intervention. A pre-procedure Duplex ultrasound examination followed by angiography and intervention were performed on all patients included in the study. Sixty-two lesions were treated with angioplasty followed by insertion of 68 MULTI-LINK VISION stents. After intervention, patients were followed at one, six and 12 month intervals with clinical examination and arterial duplex study. The survival of the studied population was 83.3%, the limb salvage was 89.3% and primary patency of treated vessel was 62.8% at 12 months. Treatment of infragenicular lesions in CLI with MULTI-LINK VISION stent is safe and effective with satisfactory limb salvage. The primary patency was acceptable, but less compared to dedicated below the knee devices.

In vitro evaluation of coronary stents and in-stent stenosis using a dynamic cardiac phantom and a 64-detector row CT scanner

The aim of the study was to examine the ability of a 64-slice MDCT to detect in-stent stenoses in an ex vivo model of coronary stents. Five different stents (Liberté, Boston Scientific; Driver, Medtronic; Multi-Link Vision, Guidant; Taxus Express, Boston Scientific; Cypher, Cordis) were examined using a dynamic cardiac phantom. The stents were pulled over a vessel model that consists of a polymer tube with diameters of 3.0, 3.5, and 4.0 mm and four different degrees of stenoses (0%; 30%; 50%; 70-80%). This model was moved with a rate of 60 bpm to mimic cardiac motion. To assess the degree of artificial signal reduction (artificial reduction of attenuation (ARA)) by the different stents, attenuation values were measured in the vessel outside the stent, and in the non-stenotic vessel inside the stent. Furthermore the grade of stenosis was assessed by two clinical observers. Highest ARA was found for the Cypher Stent (35 HU), whereas the Liberté Stent presented the lowest ARA (16 HU). Depending on the stent and the vessel diameter, up to 87.5% of the stenoses were correctly diagnosed. In the 3.0 and 3.5 mm vessels, a nonstenotic or low-grade stenotic vessel was diagnosed as intermediate or high-grade stenosis in 22.5%, whereas in the 4.0 mm vessels, this kind of overestimation did not occur. A 50% stenosis was diagnosed as a 30% stenosis in 30%. On the other hand, high-grade stenoses were underestimated in only 10%. On a four-point scale, the average deviation from the real grade of stenosis was 0.21 for the Liberté stent, 0.54 for the Taxus Express stent, 0.29 for Driver stent, 0.62 for the Multi-Link Vision stent, and 0.37 for the Cypher stent. In a dynamic cardiac phantom model, high grade stenoses in vessels with a diameter of 4 mm could be reliably detected irrespective of the stent type used in this study. Vice versa, high grade stenoses (> or = 50%) could only be ruled out with certainty in vessels with a diameter of 4 mm. In smaller vessels, the ability to correctly diagnose high-grade stenoses was dependent on the type of stent and the imaging artifacts associated with it.

Exercise Reduces TRP Channel-Mediated Calcium Influx in Smooth Muscle Cells from Atherosclerotic Coronary Arteries after Stenting in a Porcine Model of Cardiometabolic Risk

BACKGROUND: Patients with diabetes or cardiometabolic risk have poor prognosis after balloon angioplasty and coronary stenting. Coronary stents greatly decrease restenosis, but accelerated coronary artery disease (CAD) in regions adjacent to the stent (peri-stent CAD) remains a concern. Ossabaw swine exhibiting characteristics of cardiometabolic risk allow us to identify mechanisms underlying this pathology. Vascular smooth muscle cell proliferation, which is mediated partly by elevated myoplasmic Ca2+increases, is a major mechanism of atherosclerosis. Transient receptor potential (TRP) Ca2+channels activated by signals associated with depletion of Ca2+from the sarcoplasmic reticulum (SR) are increased in proliferating smooth muscle cells. Exercise has been shown to prevent SR Ca2+dysregulation in CAD, thus may protect against the increase in TRP channel-mediated Ca2+influx. HYPOTHESIS: Exercise attenuates the increase in TRP channel-mediated Ca2+influx in smooth muscle cells of non-stented arteries and in peri-stented regions from obese Ossabaw swine with cardiometabolic risk compared to healthy swine. METHODS: Male Ossabaw swine were fed control chow or 2% cholesterol/high fat diet, sedentary (H) and exercised trained (HX). Multi-link bare metal stents were placed with 1:1 apposition (not over-inflation injury) verified by intravascular ultrasound (IVUS) after 40-55 weeks on the diets. Percent stenosis was assessed using IVUS 4 weeks later. Coronary smooth muscle cells were dispersed from segments 2-5 mm proximal to the stent (peri-stent) and loaded the fluorescent Ca2+indicator fura-2. Cells were exposed to caffeine (5 mM) to release and deplete the SR Ca2+store in the presence of the sarco-endoplasmic Ca2+ATPase (SERCA) inhibitor cyclopiazonic acid (10μM) to assess peak TRP channel-mediated Ca2+influx. RESULTS: Peri-stented regions had significantly greater stenosis compared to all other segments of the artery aside from the area within the stent. Nifedipine-insensitive, TRP channel-mediated Ca2+influx in cells from the Ossabaw swine model of the metabolic syndrome were observed. Ca2+influx via TRP channels was greater in H compared to C and HX in non-stented arteries. Elevations in TRP channel-mediated Ca2+influx in peri-stented segments having greater stenosis than non-stented arteries in C and H was significantly attenuated in the HX group. CONCLUSION: Arterial segments with greatest stenosis have greatest TRP channel-mediated Ca2+influx, which is prevented by exercise training.