Nitinol Stent Research Articles

Comparative study on the mechanical properties of lower limb arterial stents under various deformation modes

Lower extremity movement is a complex and large range of limb movement. Arterial stents implanted in lower extremity are prone to complex mechanical deformation, so the stent is required to have high comprehensive mechanical properties. In order to evaluate the mechanical property of different stents, in this paper, finite element method was used to simulate and compare the mechanical properties of six nitinol stents (Absolute Pro, Complete SE, Lifestent, Protégé EverFlex, Pulsar-35 and New) under different deformation modes, such as radial compression, axial compression/tension, bending and torsion, and the radial support performance of the stents was verified by experiments. The results showed that the comprehensive performance of New stent was better than other stents. Among which the radial support performance was higher than Absolute Pro and Pulsar-35 stent, the axial support performance was better than Complete SE, Lifestent and Protégé EverFlex stent, the flexibility was superior to Protégé Everflex stent, and the torsion performance was better than Complete SE, Lifestent and Protégé Everflex stent. The TTR2 type radial support force tester was used to test the radial support performance of 6 types, and the finite element analysis results were verified. The mechanical properties of the stent are closely related to the structural size. The result provides a reference for choosing a suitable stent according to the needs of the diseased location in clinical applications.

Clinical implications of the invagination of an interwoven nitinol stent: a single-center retrospective analysis.

Stent invagination (SIV) sometimes occurs during interwoven nitinol stent (IWS) placement due to its complex deployment system. It may cause stent malapposition and reduce the minimum stent area. However, the clinical implications of SIV remain unclear. This retrospective single-center study sought to assess the clinical implications of IWS invagination in the femoropopliteal lesions in patients with peripheral arterial diseases. Thirty-two consecutive patients (23 men, mean age of 74years, 34 limbs) with symptomatic femoropopliteal lesions who had received IWS implantation from January to July 2019 were enrolled. The study was approved by the ethics committee of our institution. The 12-month primary patency rate after the initial IWS placement was evaluated as the primary outcome, which was compared between lesions with SIV (SIV cohort) and without SIV (non-SIV cohort). All IWSs were deployed successfully, but nine cases (26.4%) of SIV occurred during placement. The mean lesion length was 22.3cm, and critical limb threatening ischemia was observed in 40.6% of the limbs. The overall 12-month primary patency rate was 78.2%. The non-SIV cohort (25 cases) showed a significantly higher primary patency rate than the SIV cohort (9 cases, 91.7% vs. 41.7%, P = 0.0149). IWS implantation showed acceptable durability in Japanese patients in a real-world setting, however, SIV during IWS placement possibly led to a lower 12-month primary patency rate.

Electrodeposition of Tantalum Coatings on Nitinol Stent and Composition of Intermetallic Compounds Forming During Electrolysis

The electroreduction of tantalum complexes in a chloride-fluoride melt was studied on tungsten, and nitinol electrodes. It was found that on a nitinol electrode in addition to the peak associated with the discharge of fluoride tantalum complexes, several peaks on the voltammogram related to the formation of intermetallic compounds of nickel and tantalum were observed. The electrodeposition of tantalum coatings from the NaCl-KCl-NaF(10 wt.%)-K2TaF7(10 wt.%) melt onto nitinol stent was investigated. The formation during electrolysis of several intermediate layers between the deposited layer and substrate was found and their microstructure and chemical composition were determined. It was determined that the surface layers of the nitinol are depleted in titanium due to corrosion in the melt. During electrodeposition a barrier intermetallic layer TiNi2.4Ta0.6 is formed, which prevents the penetration of tantalum into the substrate, but does not prevent the diffusion of nickel and titanium from the substrate into the deposited layer of tantalum.

Drug-Loaded, Polyurethane Coated Nitinol Stents for the Controlled Release of Docetaxel for the Treatment of Oesophageal Cancer.

For several decades, self-expanding metal stents (SEMSs) have shown significant clinical success in the palliation of obstructive metastatic oesophageal cancer. However, these conventional oesophageal stents can suffer from stent blockage caused by malignant tumour cell growth. To overcome this challenge, there is growing interest in drug-releasing stents that, in addition to palliation, provide a sustained and localized release of anticancer drugs to minimise tumour growth. Therefore, in this study we prepared and evaluated an oesophageal stent-based drug delivery platform to provide the sustained release of docetaxel (DTX) for the treatment of oesophageal cancer-related obstructions. The DTX-loaded oesophageal stents were fabricated via dip-coating of bare nitinol stents with DTX-polyurethane (PU) solutions to provide PU coated stents with DTX loadings of 1.92 and 2.79% w/w. Mechanical testing of the DTX-PU coated stents revealed that an increase in the drug loading resulted in a reduction in the ultimate tensile strength, toughness and Young’s modulus. In vitro release studies showed a sustained release of DTX, with ~80–90% released over a period of 33 days. While the DTX-loaded stents exhibited good stability to gamma radiation sterilisation, UV sterilisation or accelerated storage at elevated temperatures (40 °C) resulted in significant DTX degradation. Cell proliferation, apoptosis and Western blotting assays revealed that the DTX released from the stents had comparable anticancer activity to pure DTX against oesophageal cancer cells (KYSE-30). This research demonstrates that the dip-coating technique can be considered as a promising approach for the fabrication of drug-eluting stents (DESs) for oesophageal cancer treatment.

The role of self-expanding vascular stent in superior vena cava syndrome for advanced tumours.

Superior vena cava (SVC) syndrome (SVCS) is a life-threatening occurrence that necessitates prompt treatment. At present, endovascular stenting is proposed as a first-line treatment to relieve symptoms. We assessed the effectiveness, safety and outcome of SVC stent positioning in patients affected with advanced cancer. Forty-two patients undergoing stent positioning in the SVC for neoplasms from January 2002 to December 2018 form the basis of this retrospective study. Demographic data, risk factors, associated diseases, symptoms at presentation according to the score proposed by Kishi and the type of SVCS according to Sanford and Doty were collected. Minor and major complications were recorded. Suspected stent occlusion was confirmed by means of recurrence of symptoms followed by a confirmatory computed tomography (CT). Thirty-four (81%) patients had a nonresectable lung tumour invading or compressing the SVC. Five (12%) patients had a non-Hodgkin's lymphoma, and three (7%) had metastatic lymphadenopathies. Nitinol stents (Memotherm®) were employed in 19 (45%) patients, and steel stents (Wallstent™) in the remaining 23 (55%) patients. Thirty-five (85%) patients died during follow up for disease progression and the overall survival rate at 24months was 11% (standard error (SE)=0.058). Thirteen patients (32%) had a recurrence of SVCS because of stent thrombosis in three (23%) and extrinsic compression from uncontrolled cancer progression in ten (77%). The overall symptom-free interval at 24months was 57% (SE=0.095). We recommend the use of the endovascular procedure as a first-line treatment in locally advanced or metastatic tumour in the presence of SVCS.

The Impact of a realistic complete Stenting Procedure on the Migration Behaviour: a Numerical Analysis

The migration of the stent graft is one of the main complications of Endovascular aneurysm repair (EVAR). It is closely related to ineffective contact between the endograft ends and the wall of the blood vessel. In this study, we have developed a realistic stent-graft deployment simulation using the Finite Element Method of 3D nitinol stent in a patient-specific Thoracic Aortic Aneurysm (TAA). This work aims to investigate the impact of the realistic complete stenting procedure by a progressive expanding deployment of the stent graft on the migration behaviour. A comparison of results is investigated between the realistic and non-realistic deployment methods to predict the overall (stent–aorta) biomechanical behaviour. We have also investigated the effect of including the graft material on the mechanical behaviour of the (stent-graft) during the deployment and the contact stability (stentgraft)/aorta after the deployment. The simulation results show that the realistic deployment method did indeed influence the mechanical behaviour, positioning, and eventually the functioning of the stent-graft when compared with the traditional deployment methods. The impact of adding the fabric tissue to the stent being deployed in an idealized straight centerline on the contact stiffness seems to be modest compared the deployed stent without graft.

Deformation mechanics of self-expanding venous stents: Modelling and experiments

Deformation properties of venous stents based on braided design, chevron design, Z design, and diamond design are compared using in vitro experiments coupled with analytical and finite element modelling. Their suitability for deployment in different clinical contexts is assessed based on their deformation characteristics. Self-expanding stainless steel stents possess superior collapse resistance compared to Nitinol stents. Consequently, they may be more reliable to treat diseases like May-Thurner syndrome in which resistance against a concentrated (pinching) force applied on the stent is needed to prevent collapse. Braided design applies a larger radial pressure particularly for vessels of diameter smaller than 75% of its nominal diameter, making it suitable for a long lesion with high recoil. Z design has the least foreshortening, which aids in accurate deployment. Nitinol stents are more compliant than their stainless steel counterparts, which indicates their suitability in veins. The semi-analytical method presented can aid in rapid assessment of topology governed deformation characteristics of stents and their design optimization.

Early thrombosis after iliac stenting for venous outflow occlusion is related to disease severity and type of anticoagulation

BackgroundStenting of the iliac venous system is often performed for symptomatic obstruction, with high patency rates reported. However, patients with post-thrombotic disease and those with more extensive obstruction have experienced poorer outcomes, including a higher rate of early post-stent thrombosis. In the present study, we examined the outcomes of patients with complete venous outflow occlusion. We focused on the variables associated with early post-stenting thrombosis to identify opportunities to reduce its incidence. MethodsFrom 2010 to 2020, the patients who had undergone stenting for chronic obstruction of the common femoral vein, iliac veins, and/or inferior vena cava were retrospectively reviewed. The pre- and intraoperative imaging studies were examined to identify those who had had total occlusion of one venous outflow segment (type III disease) or multiple venous outflow segments (type IV disease). The patient characteristics and procedural and post-stent variables were recorded. The post-procedure follow-up visits and imaging studies were reviewed to determine stent patency and thrombotic complications. Key variables were studied to determine their association with early stent reocclusion. ResultsA total of 106 patients were identified, including 43 with type III (40.6%) and 63 with type IV (59.4%) disease. The mean patient age was 49.8 ± 13.7 years, and the mean stented length was 177.3 ± 63 mm. Stainless steel Wallstents were used solely in 44% of the cases, with a variety of nitinol stents used in the remainder. Femoral vein inflow was minimally diseased in 50% of the cases, moderately diseased in 26%, and severely diseased or occluded in 24%. Antiplatelet medications were prescribed after intervention for 52.8% and anticoagulation medication for 95.3% of the patients. Occlusion of the stented segment occurred within 3 months in 25.5%. Primary patency was 74.5% at 3 months, 63.9% at 12 months, and 58.5% at 3 years. Secondary patency was 93.4% at 3 months and 76.1% at 3 and 5 years. Univariate analysis of variables related to early stent thrombosis identified the presence of a hypercoagulable state, type IV obstruction, and the type of anticoagulation used after stenting were associated with early stent thrombosis. On multivariate analysis, each of these variables was independently associated with early stent thrombosis. The presence of type IV obstruction (odds ratio [OR], 4.596; 95% confidence interval [CI], 1.424-18.109) or a hypercoagulable state (OR, 3.835; 95% CI, 1.207-12.871) was associated with significantly greater odds of reocclusion than was class III obstruction and no hypercoagulable state. Treatment with low-molecular-weight heparin for >10 days was associated with significantly lower odds (OR, 0.012; 95% CI, 0.001-0.130) of reocclusion. ConclusionsPatients who require recanalization of a completely occluded venous outflow tract before stenting have a high rate of early reocclusion. Patients with more extensive occlusion and a hypercoagulable state have greater odds of reocclusion. Treatment with low-molecular-weight heparin for >10 days reduced the odds of early reocclusion.

The implications of magnetic resonance angiography artifacts caused by different types of intracranial flow diverters

BackgroundSerial cerebral angiographic imaging is necessary to ensure cerebral aneurysm occlusion after flow diverter placement. Time-of-flight (TOF)-magnetic resonance angiography (MRA) is used for this purpose due to its lack of radiation, contrast media and complications. The comparative diagnostic yield of TOF-MRA for different flow diverters has not been previously analyzed.PurposeTo evaluate the diagnostic accuracy of TOF-MRA in cerebral aneurysms treated w divertersith different flow diverters.Materials and MethodsFlow-diverted patients whose cerebral follow-up MRA and digital subtraction angiograms (DSA) were obtained within 6 weeks were retrospectively identified. The DSA (as gold standard) and MRA images of these patients were compared by two readers (blinded to both patient data and endovascular procedure data) for residual aneurysms and the status of the parent artery for each type of flow diverter. In a second group of patients, magnetic susceptibility artifacts were manually measured and compared for different FDs.ResultsSeventy-six patients (85 aneurysms) were included in group one, and 86 patients (95 aneurysms) were included in group 2. TOF-MRA and DSA showed almost perfect agreement for residual aneurysms (κ = 0.88, p < 0.001) (positive predictive value (PPV) = 1.00, specificity = 1.00, negative predictive value (NPV) = 0.89, sensitivity = 0.89). Intermodality agreement (κ = 0.97 vs. κ = 0.74, p < 0.005) and sensitivity (0.97 vs. 0.77, NPV: 0.96 vs. 0.77) were highest with nitinol stents. MRA and DSA showed no agreement for occluded or stenotic parent vessels (κ = 0.13, p = 0.015, specificity = 0.44, NPV = 1.00, sensitivity = 1.00). Specificity was lower in chromium-cobalt based FDs than in nitinol devices (specificity = 0.08 vs. 0.60). Chromium-cobalt stents generated the largest artifacts (p < 0.005). The size of the device-related artifact, in millimeters, increased in respective order, for the Silk, Derivo, Pipeline and Surpass devices.ConclusionUnlike DSA, TOF-MRA is susceptible to dissimilarities between flow diverters. MRA is not well-suited for research studies comparing different flow diverters. Nitinol FDs appear to be advantageous for TOF-MRA follow-up so as not to miss small aneurysm remnants or clinically relevant parent artery stenosis.

Surgical repair and subsequent stent placement following traumatic trans‐rectal urethral transection in a dog

AbstractA one‐year‐old male castrated Australian Shepherd presented for rectal trauma after falling into bushes. A 10‐cm long segment of tissue protruded from the anus, and there were no other visible injuries. Abdominal radiographs showed intrapelvic and perirectal subcutaneous emphysema extending into fascial planes of the right hindlimb. Exploratory surgery was performed, and the tissue protruding out of the anus was identified as proximal urethra extending through a 6 cm longitudinal tear in the ventral rectal wall. Urethral debridement and anastomosis were performed, and the rectal wall repaired. A urinary catheter was in place for 5 days postoperatively. The patient had intermittent episodes of stranguria and pollakiuria and multi‐drug resistant urinary tract infection (Enterococcus faecium) cultured. A pelvic urethral stricture was diagnosed on contrast cystourethrogram, and a nitinol stent placed under fluoroscopic guidance. Sporadic haematuria was observed, which was resolving in a few months. Urethral stent placement provided successful long‐term outcome.

Correction to: Self-Expandable Nitinol Stents for the Treatment of Nonmalignant Deep Venous Obstruction.

Correction to: Self-Expandable Nitinol Stents for the Treatment of Nonmalignant Deep Venous Obstruction.

Citric acid functionalized nitinol stent surface promotes endothelial cell healing.

While drug-eluting stents containing anti-proliferative agents inhibit proliferation of smooth muscle cells (SMCs), they also delay the regrowth of the endothelial cells which can result in subsequent development of restenosis. Acidic extracellular environments promote cell anchorage and migration by inducing conformational change in integrins, the main cell adhesion proteins. This study addresses the feasibility of a citric acid (CA) functionalized nitinol stent for improving vascular biocompatibility, specifically enhancing endothelialization. CA functionalized nitinol vascular stents are compared to commercial bare metal (Zilver Flex) and paclitaxel eluting stents (Zilver PTX) in terms of re-endothelialization. To study the effect of stent coatings, a stent conditioned media methodology was developed in an attempt to represent in vivo conditions. Overall, distinct advantages of the CA functionalized nitinol stent over commercial Zilver PTX DES and Zilver Flex BMS stents in terms of endothelial cell adhesion, migration, and proliferation are reported. These novel findings indicate the potential of a CA functionalized stent to serve as a bioactive and therapeutic surface for re-endothelialization, perhaps in combination with a SMC proliferation inhibitor coating, to prevent restenosis.

Implantation of a Sutureless Valve Into a Surgically Enlarged Aortic Root: A Bailout Option

Sutureless bioprostheses such as the Sorin Perceval Valve (SPV; Sorin Group, Srl, Saluggia, Italy) have been proposed for replacing stenotic native valves within small aortic roots of geriatric patients with significant comorbidity. Their use seems as safe as that of stented bioprostheses and enables significantly reduced length of surgery. Low transprosthetic pressure gradients have been measured. Because of the radial force of its self-expandable nitinol stent, aortic annulus interruption could be a relative contraindication to SPV use. Off-label implantation of the SPV into a surgically enlarged ascending aorta was first reported in this study, as a bailout option in the presence of a tiny aortic root.

Pre-procedural color duplex ultrasound evaluation predicts restenosis after long-segment superficial femoral artery stenting.

Restenosis after stenting for superficial femoral artery atherosclerotic disease remains a significant clinical problem, especially for long-segment lesions. We assessed predictors of in-stent restenosis in patients with long-segment superficial femoral artery disease and hypothesized that pre-procedural ultrasound assessment would predict in-stent restenosis. This single-center study retrospectively analyzed 283 limbs in 243 patients who treated with superficial femoral artery nitinol stent placement for long-segment (≥15 cm) lesions between 2015 and 2018. Color duplex ultrasound was performed pre-procedure and post-procedure at 3, 6, 12, 24, and 36 months. The endpoint was ≥50% in-stent restenosis in the superficial femoral artery. Primary patency rates were analyzed with Kaplan-Meier survival analysis and compared using the log-rank test. A multivariable Cox proportional hazards model was used to evaluate the risk factors for in-stent restenosis. The median length of lesions was 25.8 ± 8.1 cm. The cumulative freedom from ≥50% in-stent restenosis at 3, 6, 12, 24, and 36 months was 95.3%, 78.3%, 56.0%, 30.6%, and 15.9%, respectively. Univariate and multivariate Cox regression analysis showed that cumulative lesion length ≥ 25 cm (hazard ratio 1.681; p = 0.003), calcified plaque (hazard ratio 1.549, p = 0.006), poor runoff scores >10 (hazard ratio 1.870, p = 0.003), and chronic renal failure (hazard ratio 2.075, p = 0.009) were independent risk factors for in-stent restenosis. The agreement rate between ultrasound and angiography was 92.6% for cumulative lesion length (κ 0.851) and 91.9% for runoff score (κ 0.872). The results indicate that pre-procedural color duplex ultrasound evaluation is helpful for the selection of appropriate candidates for superficial femoral artery stent placement. Cumulative lesion length ≥25 cm, plaque calcification, poor distal runoff, and chronic renal failure independently predicted in-stent restenosis.

Drug-Coated Balloon versus Bare Nitinol Stent in Femoropopliteal Artery: 12 Months Outcome from a Single Center in China

The study sought to compare the safety and effectiveness of drug-coated balloon (DCB) with bare nitinol stent in patients with complex femoropopliteal(FP) lesions in real-world practice. Patients with symptomatic (Rutherford stage 2 to 5) femoropopliteal lesions who underwent DCB or bare nitinol stent implantation at the Department of Cardiovascular Surgery of China-Japan Friendship Hospital from June 2016 to September 2017 were included. Demographics, angiographic and procedural variables were included. Freedom from target lesion revascularization (TLR), primary patency and major adverse events were obtained from follow-up results at 3,6 and12 months. Descriptive analysis was performed on all variables. A total of 90 eligible patients were enrolled, which included 51 DCB subjects (mean age, 63.1 ± 13.2 years; 76.5% male) with 55 lesions and 39 nitinol stent subjects (mean age, 66.5 ± 10.5 years; 61.5% male) with 42 lesions. Significant higher primary patency was observed in the DCB group compared with the stent group (74.5% vs. 52.4%; log-rank test P = 0.018; HR 0.335, 95%CI 0.124-0.903, P = 0.031). The rates of freedom from TLR (f-TLR) were 78.2% and 59.5% (log-rank test P = 0.032) for the DCB group and the stent group, respectively, at 12 months. CD-TLR rates were 18.2% vs. 38.1% with a P-value of 0.023. Female sex (HR 6.122, 95%CI 1.880-19.934, P = 0.003), lesion length over 20 cm (HR 5.514, 95%CI 2.312-13.148, P < 0.001) and renal insufficiency (HR 2.609, 95%CI 1.087-6.260, P = 0.032) were suggested as independent risk factors of reducing primary patency. There were no significant differences in major adverse events between the 2 groups. The result above demonstrates that DCB treatment has higher primary patency and lower TLR at 12 months than nitinol stent. These data confirm the safety and effectiveness of the DCB for patients with complex femoropopliteal lesions.

Transcatheter pulmonary valve replacement: a new polycarbonate urethane valve.

Transcatheter pulmonary valve replacement has become a valid treatment option for right ventricular outflow tract diseases. However, some limitations occur in patients with wide, compliant right ventricular outflow tracts that might be amenable to treatment with self-expanding valved protheses. An experimental ovine study was designed to evaluate a novel dip-coated, low-profile trileaflet polycarbonate urethane (PCU) heart valve mounted into a self-expandable nitinol stent. The PCU valves were produced by a dip-coating technique, mounted in a conical-shaped nitinol stent and provided with a leaflet thickness of 100-150 µm. The valved stents were implanted percutaneously via transfemoral access in 6 consecutive sheep divided into 2 groups. Three animals were followed up for 1 month and the remainder, for 6 months. Angiographic measurements and transthoracic echocardiography were performed before and after implantation and at the end of the 1- or 6-month observation period, respectively. Orthotopic positioning of the valve was achieved in all animals. All except 1 had competent valves during the follow-up period. The peak-to-peak gradient across the PCU valved stents was 4.6 ± 1.0 mmHg after 1 month and 4.4 ± 2.3 mmHg after 6 months of follow-up. Macroscopic and microscopic post-mortem evaluation indicated good morphological and structural results. There were no stent fractures, leaflet calcification or thrombus formation. This study demonstrates successful transcatheter pulmonary valve replacement with a novel dip-coated valved nitinol stent. The trileaflet PCU prostheses indicated good functional and biocompatible properties after a 6-month observation period.

Transcatheter Mitral Valve Replacement: A Novel Anchor Technology.

Mitral valved stents tend to migrate or to develop paravalvular leakage due to high-left ventricular pressure in this cavity. Thus, this study describes a newly developed mitral valved stent anchoring technology. Based on an existing mitral valved stent, four anchoring units with curved surgical needles were designed and fabricated using three-dimensional (3D) software and print technology. Mitral nitinol stents assembled with four anchoring units were successively fixed on 10 porcine annuli. Mechanical tests were performed with a tensile force test system and recorded the tension forces of the 10 nitinol stents on the annulus. The average maximum force was 28.3 ± 5.21 N, the lowest was 21.7 N, and the highest was 38.6 N until the stent lost contact with the annulus; for the break force (zero movement of stent from annulus), the average value was 18.5 ± 6.7 N with a maximum value of 26.9 N and a minimum value of 6.07 N. It was additionally observed that the puncture needles of the anchoring units passed into the mitral annulus in all 10 hearts and further penetrated the myocardium in only one additional heart. The anchoring units enhanced the tightness of the mitral valved stent and did not destroy the circumflex coronary artery, coronary sinus, right atrium, aortic root, or the left ventricular outflow tract. The new anchoring units for mitral nitinol stents were produced with 3D software and printing technology; with this new type of anchoring technology, the mitral valved stent can be tightly fixed toward the mitral annulus.

A computational study of fatigue resistance of nitinol stents subjected to walk‐induced femoropopliteal artery motion

Fatigue resistance of nitinol stents implanted in femoropopliteal arteries is a critical issue because of their harsh biomechanical environment. Limb flexions due to daily walk expose the femoropopliteal arteries and, subsequently, the implanted stents to large cyclic deformations, which may lead to fatigue failure of the smart self-expandable stents. For the first time, this paper utilised the up-to-date measurements of walk-induced motion of a human femoropopliteal artery to investigate the fatigue behaviour of nitinol stent after implantation. The study was carried out by modelling the processes of angioplasty, stent crimping, self-expansion and deformation under diastolic-systolic blood pressure, repetitive bending, torsion and axial compression as well as their combination. The highest risk of fatigue failure of the nitinol stent occurs under a combined loading condition, with the bending contributing the most, followed by compression and torsion. The pulsatile blood pressure alone hardly causes any fatigue failure of the stent. The work is significant for understanding and improving the fatigue performance of nitinol stents through innovative design and procedural optimisation.

Endovascular balloon angioplasty for infrainguinal arterial occlusive disease: Efficacy analysis.

Background We present early and mid-term clinical outcomes of endovascular revascularization for femoropopliteal involvement of peripheral arterial disease. Methods A total of 128 patients (113 males, 15 females; mean age: 63.4±9.9 years; range, 32 to 87 years) who underwent percutaneous transluminal angioplasty for femoropopliteal lesions between August 2016 and April 2018 were analyzed retrospectively. Treatment with Luminor® paclitaxel-coated drug-eluting balloon catheter or bailout therapy with iVolution® self-expanding nitinol stent were performed. Overall patency rates and freedom from reintervention rates were analyzed using the Kaplan-Meier analysis. The primary patency and freedom from reintervention to target lesion rates at 12 and 24 months were evaluated. Results Technical success was achieved in 133 (93%) of the interventions with a median follow-up of 11 (range, 1 to 35) months. At 12 and 24 months, the mean overall patency rates were 85.6±3.7% and 66.8±6.7%, respectively and the mean freedom from reintervention to target lesion rates were 91.6±2.9% and 78.1±6.3%, respectively. The primary patency and freedom from reintervention to target lesion rates were significantly higher in the bailout stenting group than the drug-eluting balloon group at 12 months (97.3±2.7% vs. 94.8±6.1%, respectively, p=0.025 and 97.1±2.9% vs. 84.2±5.5%, respectively, p=0.005) and at 24 months (76.9±7.9% vs. 55.8±13.4%, respectively, p=0.025 and 85.2±7.0% vs. 70.2±13.6%, respectively, p=0.005). Conclusion Endovascular procedures including drug-eluting balloon and bailout stenting seem to be effective alternative treatment modalities for treatment of infrainguinal peripheral arterial disease and can be also used in patients with long lesions and/or total occlusion of femoropopliteal arteries.

Endovascular Relining of Chronically Occluded Infrainguinal Venous Bypass Grafts

Treatment of chronically occluded infrainguinal venous bypass grafts in patients presenting with recurrent chronic limb threatening limb ischemia (CLTI) represent a clinical challenge. Recent case reports have suggested the use of endovascular recanalization techniques without preceding thrombolysis. This study assesses feasibility and mid-term outcomes of this technique. A retrospective review of 5 consecutive patients (3 men, 2 women, mean age 70 ± 5 years) presenting with chronic venous bypass graft occlusion and recurrence of CLTI during 1 year was performed. Patients were treated with relining of the bypass grafts. Patients were followed up at median 26 (6-36) months. All patients were treated successfully with restoration of flow in the grafts using recanalization and relining technique without thrombolysis. In 4 patients, a Viabahn stentgraft (SG) was used with the addition of interwoven nitinol stents (INS) in 3. In 1 patient, the graft was treated with INS without the addition of a stentgraft. No peripheral embolization was encountered during the procedures. One patient occluded the relined grafts after 6 months. The remaining 4 grafts were all patent at 24-month follow-up. A total of 6 reinterventions (in 3 patients) were performed to reach 80% secondary patency. This case series demonstrate feasibility and promising mid-term results, from relining of chronically occluded infra-inguinal venous bypass grafts using stent grafts, interwoven and bare-metal stents without preceding thrombolysis. The technique could be an alternative treatment option in the treatment of these challenging cases.