Physical Properties of Venous Stents: An Experimental Comparison

Magnetizable Flow Diverters Can Magnetically Capture and Retain Endothelial Cells to Promote Healing in Rabbit Arteries

Flow diverters are effective endovascular devices used to treat intracranial aneurysms by facilitating aneurysm occlusion through endothelial growth across the aneurysm neck. Rapid endothelialization reduces complications such as thrombosis and stenosis. This technical note describes braided, magnetizable flow diverters made from stainless steel alloy 2205 (SS2205) wires designed to magnetically capture autologous blood outgrowth endothelial cells (BOECs) labeled with superparamagnetic iron oxide nanoparticles (SPIONs). Preclinical rabbit artery deployments demonstrated successful magnetic capture and retention of SPION-labeled BOECs, indicating feasibility for accelerated endothelialization. Detailed technical specifications provided in this manuscript ensure precise reproducibility, aiding future studies exploring advanced endothelialization strategies in neuroradiology.

Learning curve in the endovascular treatment of chronic post-thrombotic syndrome in a French center

PURPOSE

Chronic post-thrombotic syndrome (PTS) is a frequent and disabling complication of deep vein thrombosis (DVT) with significant clinical impact. Endovascular stenting (EVS) has established itself as an effective technique but its availability remains limited to expert centers. We sought to identify the key determinants of our learning curve in EVS for PTS and the impact of this experience on our short and long-term results, in order to facilitate territorial dissemination and respond effectively to clinical demand.

MATERIAL AND METHODS

We reviewed the records of 68 patients treated in our centre during eight years. We collected patients and disease characteristics, technical elements of the procedure, peri-procedural medical management and detail of the clinical follow-up and imaging.

RESULTS

The median follow-up was 37 months. The primary, primary assisted and secondary patency rates were respectively 74%, 86% and 95%. A clinical benefit was observed in all patients from the start of our activity, without significant change whatever the operator experience. The main determinants of our learning curve were a progressive mastery of the procedure in its technicality and preparation, the evolution of the material and the improvement of the peri procedural management, allowing to reduce the duration of intervention, the rate of endovascular revision (38% to 4%, p < 0.01) but also the number of remote thrombotic events (29% to 6%).

CONCLUSION

EVS appears to be an effective therapeutic option in the management of PTS, with consistent clinical improvement observed even when performed by less experienced operators. Improvement in this technique comes with faster procedures, and a reduction of the occurrence of peri-procedural and long term thrombotic events. The implementation of this type of procedure requires multi-disciplinary collaboration with vascular medicine and corresponding angiologists.

Pelvic Varicose Veins in Women. Russian Experts Consensus

Pelvic Varicose Veins in Women. Russian Experts Consensus.

Effects of structural design on the mechanical performances of poly-L-lactic acid cardiovascular scaffolds using FEA and in vitro methods

OBJECTIVE

In this study, we propose distinct and novel types of scaffold geometries to improve the mechanical performance of Poly-L-lactic Acid (PLLA) bioresorbable vascular scaffolds (BVS), investigating how different geometries of PLLA BVS influence their mechanical performances through finite element analysis (FEA) and in vitro experiment methods.

METHODS

Four different types of scaffold geometries were modelled for FEA and manufactured for in vitro experiments. PLLA tubes with 110 μm thickness were used in manufacturing the scaffolds. For FEA measurements, material properties and bilinear material models were obtained from tensile testing using the PLLA tubes employed for manufacturing. Various measurements were conducted including crush resistance, radial strength in both the laser-cut and deployed state, three-point bending, and scaffold crimping/expansion test.

RESULTS

Overall, the FEA results were similar to the experimental results. Design A, which had a conventional open-cell geometry with straight bridges, showed inferior crush resistance and radial strength to those of the other tested geometries. Design B exhibited the most well-balanced scaffold performances in terms of radial strengths, crush resistance, three-point bending, and crimping/expansion behaviors. Notably, it showed minimum plastic strain during crimping and expanding deformations in FEA.

CONCLUSIONS

Findings from such distinct and novel types of scaffold geometries shown by this study may provide a valuable understanding using PLLA scaffolds as cardiovascular devices.

Early outcome of stenting for treating iliac vein compression syndrome combined with acute deep venous thrombosis

AIM

The present study assessed the effectiveness and safety of stent placement for treating iliac vein compression syndrome (IVCS) with acute deep venous thrombosis (DVT).

MATERIALS AND METHODS

We conducted a retrospective study on 31 patients with IVCS companied with acute DVT who underwent percutaneous mechanical thrombectomy or catheter-directed thrombolysis and angioplasty combined with iliac vein stenting from January 2017 to January 2023. Follow-up was performed at 3, 6, and 12 months after the surgical procedure. At each visit, patients were evaluated by colour Doppler ultrasound or computed tomography venography to determine stent patency; additionally, visual analog scale (VAS), venous clinical severity score (VCSS), and five-level EuroQol-five dimensions (EQ-5D-5L) questionnaire were used to assess pain, severity, and symptoms associated with venous pathology and quality of life, respectively.

RESULTS

The technical success rate of stent placement was 100 % in all patients. All patients completed follow-up at 3, 6, and 12 months after surgery. The primary patency rates were 96.8 % (95 % CI: 90.2-103.4 %) at 3, 6, and 12 months. The secondary patency rate was 96.8 % (95 % CI: 90.2-103.4 %) at 3 months and 100 % at 6, and 12 months. Only one patient experienced in-stent restenosis and underwent reintervention postoperation. All patients showed a significant improvement (P<0.05) in the scores of VAS, VCSS, and EQ-5D-5L.

CONCLUSION

Venous stent implantation was a safe and effective therapeutic approach for patients with IVCS combined with acute DVT.

Safety and efficacy assessment of the Inno-Xmart venous stent system in managing symptomatic iliofemoral venous obstruction: a 12-month outcome analysis

This study aims to evaluate the safety and efficacy of the dedicated Inno-Xmart braided venous stent system (Suzhou Innomed Medical Device Co., Ltd., Jiangsu, China) in treating symptomatic iliofemoral venous obstruction. This clinical study followed a prospective, multicentre, single-arm design with the application of an objective performance goal. Patients diagnosed with symptomatic iliofemoral venous obstruction who met the eligibility criteria of this study were enrolled and treated with the Inno-Xmart venous stent system. The safety endpoints included the assessment of stent fracture, satisfaction of delivery system and 12-month incidence rate of major adverse events (MAEs). The primary efficacy endpoint focused on evaluating the 12-month primary patency rate through venography as determined by core laboratory. Secondary efficacy endpoints included surgical success rate, 6-month primary patency rate and the changes in quality of life from baseline to 6- and 12-month follow-up intervals. Between September 18, 2019, and April 26, 2021, 193 patients were successfully enrolled across 18 research institutions. The surgical success rate was 95.3% (184/193), the 12-month MAE rate was 5.1% (9/178) with no stent fractures or migrations. The 12-month primary patency rate for the participants was 96.1%, significantly surpassing the literature-derived objective performance of 80% (95% confidence interval [CI], 92.1-98.4; P < 0.0001). In addition, the mean venous clinical severity score (VCSS) and Chronic Venous Disease Quality of Life Questionnaire (CIVIQ) scores at the 6- and 12-month follow-ups were significantly lower than the preoperative scores (P < 0.001). The innovative, dedicated braided venous stent designed to address symptomatic iliofemoral venous obstruction demonstrates a high technical success rate, low complication rates, and impressive mid-term (12-month) patency. It effectively enhanced the quality of life for patients and holds promising prospects for a wide range of applications. The clinical study was officially registered in the "Chinese Clinical Trial Registry" (Registration number: ChiCTR2000040216, date of registration: November 25th, 2020).

Radiopaque FeMnN-Mo composite drawn filled tubing wires for braided absorbable neurovascular devices

Flow diverter devices are small stents used to divert blood flow away from aneurysms in the brain, stagnating flow and inducing intra-aneurysmal thrombosis which in time will prevent aneurysm rupture. Current devices are formed from thin (∼25 μm) wires which will remain in place long after the aneurysm has been mitigated. As their continued presence could lead to secondary complications, an absorbable flow diverter which dissolves into the body after aneurysm occlusion is desirable. The absorbable metals investigated to date struggle to achieve the necessary combination of strength, elasticity, corrosion rate, fragmentation resistance, radiopacity, and biocompatibility. This work proposes and investigates a new composite wire concept combining absorbable iron alloy (FeMnN) shells with one or more pure molybdenum (Mo) cores. Various wire configurations are produced and drawn to 25-250 μm wires. Tensile testing revealed high and tunable mechanical properties on par with existing flow diverter materials. In vitro degradation testing of 100 μm wire in DMEM to 7 days indicated progressive corrosion and cracking of the FeMnN shell but not of the Mo, confirming the cathodic protection of the Mo by the FeMnN and thus mitigation of premature fragmentation risk. In vivo implantation and subsequent μCT of the same wires in mouse aortas to 6 months showed meaningful corrosion had begun in the FeMnN shell but not yet in the Mo filament cores. In total, these results indicate that these composites may offer an ideal combination of properties for absorbable flow diverters.

Indications, technical aspects, and outcomes of stent placement in chronic iliofemoral venous obstruction

BACKGROUND

Iliofemoral venous stent placement (IVS) has evolved to a well-established endovascular treatment modality for chronic iliofemoral venous obstruction (CIVO). Dedicated venous stents gained approval from the US Food and Drug Administration in 2019 and solidified IVS as a defined intervention with clear indications, contraindications, risks, benefits, and procedural management principles. This review focuses on the indications, technical aspects and outcomes of stenting for CIVO. Other aspects pertaining to IVS are covered in other articles that are a part of this series.

METHODS

This study conducted a literature search limited to English articles. Three search strategies were used, and references were managed in Covidence software. Four investigators screened and evaluated articles independently, excluding meta-analyses, clinical trial protocols, and nonrelevant studies. Eligible studies, focused on clinical outcomes and stent patencies, underwent thorough review.

RESULTS

The literature search yielded 1704 studies, with 147 meeting eligibility criteria after screening and evaluation. Exclusions were based on duplicates, irrelevant content, and noniliac vein stent placement.

CONCLUSIONS

Successful IVS for CIVO relies on meticulous patient selection, consistent use of intravascular ultrasound examination during procedures and attention to the technical details of IVS.

Review of the literature supporting international clinical practice guidelines on iliac venous stenting and their applicability to Australia and New Zealand practice

BACKGROUND

The overall goal of this report is to provide a high-level, practical approach to managing venous outflow obstruction (VOO).

METHODS

A group of vascular surgeons from Australia and New Zealand with specific interest, training, and experience in the management of VOO were surveyed to assess current local practices. The results were analyzed and areas of disagreement identified. After this, the group performed a literature review of consensus guidelines published by leading international organizations focused on the management of chronic venous disease, namely, the Society for Vascular Surgery, American Venous Forum, European Society for Vascular Surgery, American Vein and Lymphatic Society, Cardiovascular and Interventional Radiology Society of Europe, and American Heart Association. These guidelines were compared against the consensus statements obtained through the surveys to determine how they relate to Australian and New Zealand practice. In addition, selected key studies, reviews, and meta-analyses on venous stenting were discussed and added to the document. A selection of statements with >75% agreement was voted on, and barriers to the guideline's applicability were identified. The final recommendations were further reviewed and endorsed by another group of venous experts.

RESULTS

The document addresses two key areas: patient selection and technical aspects of venous stenting. Regarding patient selection, patients with clinically relevant VOO, a Clinical-Etiologic-Anatomic-Physiologic score of ≥3 or a Venous Clinical Severity Score for pain of ≥2, or both, including venous claudication, with evidence of >50% stenosis should be considered for venous stenting (Level of Recommendation Ib). Patients with chronic pelvic pain, deep dyspareunia, postcoital pain affecting their quality of life, when other causes have been ruled out, should also be considered for venous stenting (Level of Recommendation Ic). Asymptomatic patients should not be offered venous stenting (Level of Recommendation IIIc). Patients undergoing thrombus removal for acute iliofemoral deep vein thrombosis, in whom a culprit stenotic lesion of >50% has been uncovered, should be considered for venous stenting (Level of Recommendation Ib).

CONCLUSIONS

Patients with VOO have been underdiagnosed and undertreated for decades; however, in recent years, interest from physicians and industry has grown substantially. International guidelines aimed at developing standards of care to avoid undertreating and overtreating patients are applicable to Australia and New Zealand practice and will serve as an educational platform for future developments.

Newly Designed, Self-Expanding Large-Bore Nitinol Stents for Symptomatic Central Venous Stenosis: Technical and Long-Term Clinical Outcome

PURPOSE

To retrospectively analyze the technical and long-term clinical outcome of angioplasty and stenting using the Venovo™ venous stent for the treatment of malignant and benign superior vena cava (SVC) occlusive disease.

MATERIALS AND METHODS

Consecutive patients treated with the Venovo™ venous stent for SVC occlusive disease were included. SVC obstruction symptoms were classified according to the Kishi score. The Wilcoxon signed-rank test was used for testing significance of changes. Technical success, defined as correct placement of the stent, completely covering and re-expanding the obstruction, between groups was tested using the Fisher exact test. Overall survival was calculated using the Kaplan-Meier method.

RESULTS

Fifty-five patients underwent stent insertion for symptomatic benign (n = 13; 24%) or malignant (n = 42; 76%) SVC occlusive disease. A significant drop in Kishi score, mean 3.91 before versus mean 1.02 after the procedure (P < 0.0001), was observed. In one patient (1.8%), an additional balloon-expandable stent was needed to manage incomplete expansion of the nitinol stent. In one patient, a procedure-related lung embolic complication was noted. Early thrombotic occlusion of the stent occurred in one patient. Late symptomatic restenosis occurred in 3 patients. Overall primary stent patency and primary-assisted stent patency were 86% (95% CI 66-95) and 97% (95% CI 83-100) at 1-year follow-up and 98% (95% CI 87-100), 98% (87-100) at 2-year follow-up, respectively.

CONCLUSION

In this retrospective analysis, angioplasty and stent placement using the Venovo™ venous stent is safe and clinically effective for the treatment of both benign and malignant SVC occlusive disease. Reintervention for symptomatic restenosis is rare.

Successful treatment of chronic venous in-stent restenosis using a Phoenix atherectomy device

BACKGROUND

Although endovascular treatment of venous obstruction with percutaneous transluminal angioplasty (PTA) and stenting is a safe and effective alternative to conservative treatment, the overall prevalence of in-stent restenosis (ISR) remains high in this patient population. This study reports a novel treatment option for patients with chronic ISR (C-ISR).

METHODS

At our center, all patients with ISR were treated based on the time since the initial intervention. Acute in-stent restenosis (A-ISR) was preferably treated with catheter-directed thrombolysis or a pharmacomechanical peripheral thrombectomy device and PTA. Selected patients with chronic ISR (C-ISR) (greater than 30 days) were treated with a catheter- guided unidirectional atherectomy in addition to PTA, under the assumption of a non-thrombotic mechanism in the development of C-ISR.

RESULTS

We demonstrate a safe and practical treatment option for chronic ISR using a catheter- guided technical approach with the Phoenix atherectomy device in four patients. Technical success was achieved in every case, and mid-term patency was restored in three out of four patients.

CONCLUSIONS

Restenosis following venous stenting is highly complex. Patients must be treated individually, with a focus on anticoagulation and antiplatelet therapy regimens, as well as the appropriate interventional treatment. Catheter- guided atherectomy is a viable option for this heterogeneous group of patients. Further studies are required to understand the etiology of chronic ISR.

Percutaneous Image-Guided Treatment of Pediatric Deep-Vein Occlusions

Pediatric venous occlusions are a growing cause of morbidity and mortality, especially in hospitalized patients. Catheter-directed recanalization is a safe and effective treatment option in appropriately selected patients. Benefits of catheter directed therapies (CDTs) include the prevention of pulmonary embolism and end organ failure acutely as well as superior vena cava syndrome and post-thrombotic syndrome chronically. Timely diagnosis, recognition of underlying factors for thrombosis, and familiarity with the spectrum of tools and techniques for CDT are essential to optimizing outcomes in the acute setting. Recanalization of chronic venous occlusions can similarly provide symptomatic relief and achieve long term vessel patency. This review will detail the scope, techniques, and outcomes for CDT in the treatment of acquired systemic deep vein occlusions.

The TOPOS study

Background: We aimed to study the long-term safety and efficacy of oblique venous stents for post-thrombotic syndrome (PTS) with iliac vein compression. Patients and methods: In the multinational, prospective, single-arm TOPOS study, PTS patients scheduled for endovascular therapy with the sinus-Obliquus® stent and optional distal extension with the sinus-Venous® or sinus-XL Flex® stent were enrolled at eight European vascular centres between October 2016 and December 2020. The primary outcome was primary stent patency at 24 months, and secondary outcomes included the clinical course of PTS (Villalta score, revised Venous Clinical Severity Score [rVCSS], Visual Analog Scale [VAS] of pain), quality of life changes (Chronic Venous Insufficiency Quality of Life Questionnaire, CIVIQ-20), and device-related complications. Results: We enrolled 60 patients (mean age 46±15 years, 68% women, 13% active ulcers): 80% required stent extension (70% below the inguinal ligament). The primary patency rate at 24 months was 80.7% (95%CI 68.1-90.0%); it was higher in patients without vs. those with stent extension (90.9% vs. 78.3%, p=.01). Compared to baseline, the Villalta, rVCSS, pain VAS, and CIVIQ-20 decreased by a median of 8 (interquartile range (IQR): 4-11), 5 (IQR: 3-7), 3 (IQR: 2-5), and 17 (IQR: 6-22) points, respectively; p<.001 for all parameters. Overall, 9 events of acute stent occlusion, 4 symptomatic stent stenosis, and 1 pulmonary embolism occurred. We did not observe major bleeding events or contralateral thrombosis. Conclusions: Endovascular treatment with the oblique stent and optional stent extension was safe and resulted in high patency rates at 24 months. The reduction in PTS severity was substantial and persisted over 2-year follow-up.

Intraluminal Flow Diverter Design Primer for Neurointerventionalists

The clinical use of flow diverters for the treatment of intracranial aneurysms has rapidly grown. Consequently, the market and technology for these devices has also grown. Clinical performance characteristics of the flow diverter are well-known to the clinician. However, the engineering design principles behind how these devices achieve ideal clinical performance are less understood. This primer will summarize flow diverter design parameters for neurointerventionalists with the aim of promoting collaboration between clinicians and engineers.

Future Directions and Innovations in Venous Sinus Stenting

This review explores the future role of venous sinus stenting (VSS) in the management of idiopathic intracranial hypertension and pulsatile tinnitus. Despite its favorable safety profile and clinical outcomes compared with traditional treatments, VSS is not yet the standard of care for these conditions, lacking high-level evidence data and guidelines for patient selection and indications. Current and recently completed clinical trials are expected to provide data to support the adoption of VSS as a primary treatment option. Additionally, VSS shows potential in treating other conditions, such as dural arteriovenous fistula and cerebral venous sinus thrombosis, and it is likely that the procedure will continue to see an expansion of its approved indications. The current lack of dedicated venous stenting technology is being addressed with promising advancements, which may improve procedural ease and patient outcomes. VSS also offers potential for expansion into modulation of brain electrophysiology via endovascular routes, offering exciting possibilities for neurodiagnostics and treatment of neurodegenerative disorders.

Iliocaval and Iliofemoral Venous Stenting for Obstruction Secondary to Tumor Compression: Single Center Experience

Background

Cancer patients with pelviabdominal masses can suffer from lower extremity symptoms due to venous compression. The effectiveness of venous stenting has been established in extrinsic venous compression in benign conditions like May-Thurner syndrome. In this retrospective study we evaluate the efficacy and safety of caval, iliocaval and iliofemoral venous stenting for cases of extrinsic venous compression caused by malignant masses in cancer patients.

Methods

IRB-approved retrospective review of patients who underwent iliofemoral venography with venoplasty and stenting between January 2018 and February 2022 was performed. Patients with extrinsic venous compression caused by malignant masses were included. Data on patient demographics, pre-procedure symptoms, procedural technique, stent characteristics, outcomes and follow-up were collected. Descriptive statistics were used to assess technical success, clinical success, primary stent patency and adverse events of the procedure.

Results

Thirty-seven patients (19 males, 18 females) who underwent 45 procedures were included. Deep venous thrombosis (DVT) was present in 21 (57%) patients. Twenty-nine patients (78%, 95% CI 62-90%) reported clinical improvement of the presenting symptoms. The median overall survival after the procedure was 4.7 months (95% CI 3.58-5.99). Eight (22%) patients were alive at last follow up with median follow up of 10.33 months (Range 2-25 months). Twenty-six patients had patent stents on their last follow up imaging (70%, 95% CI 61%-91%). Two patients had a small access site hematoma which resolved spontaneously. Two patients developed moderate, and 1 patient developed severe adverse events related to post procedure therapeutic anticoagulation.

Conclusion

Venous stenting is a safe procedure and should be considered as part of the palliative care for patients with debilitating lower extremity symptoms related to iliocaval and iliofemoral venous compression.

Coaxial Placement of Balloon-Expandable and Self-Expanding Stents: Impact on Crush Resistance and Luminal Recovery in a Benchtop Model

During endovascular interventions, coaxial deployment of stents may be required to preserve luminal gain. This study characterized in vitro the effect on crush resistance and postcompression recovery when 316L stainless steel balloon-expandable (BE) and laser-cut nitinol self-expanding (SE) venous stents were deployed coaxially. Various stent configurations were parallel-plate compressed from a fully expanded state to 50% diameter reduction (Criterion, Model 42; MTS, Eden Prairie, Minnesota) in a 37 °C ± 1 water bath. Coaxial deployments of SE stent inside BE stent and BE stent inside SE stent demonstrated higher crush resistances compared with each stent individually or their mathematical summation (analysis of variance P < .0001; pairwise comparison P < .01). The configuration of SE stent inside BE stent showed higher postcompression luminal recovery at 48.7% compared with that of BE stent inside SE stent at 27.5% (P = .0001). Coaxial deployment of SE stent inside BE stent may improve crush resistance and luminal recovery after compression in the appropriate clinical context.

Double-Barrel Nitinol Stent Placement for Iliocaval Reconstruction: The Effect of Deployment Sequence and Direction on Final Configuration

Double-barrel stent placement across the iliocaval confluence is commonly used for the treatment of chronic bilateral iliocaval occlusion. The difference in the deployment outcomes of synchronous parallel stent deployment versus asynchronous or antiparallel deployment and the underlying stent interactions are poorly understood. In this study, 3 strategies of double-barrel nitinol self-expanding stent deployment across the iliocaval confluence (synchronous parallel, asynchronous parallel, and synchronous antiparallel) were contrasted in vivo in 3 swine followed by assessment of the explanted stent construct. Synchronous parallel stent deployment achieved a desired double-barrel configuration. The asynchronous parallel and antiparallel deployment strategies both resulted in a crushed stent despite subsequent simultaneous balloon angioplasty. These animal model results suggested that in patients who undergo double-barrel iliocaval reconstruction, synchronous parallel stent deployment may provide the desired stent conformation and increase the chance for clinical success.

Pregnancy outcomes in 16 women with previous catheter-directed thrombolysis and stenting for acute left iliofemoral deep vein thrombosis

BACKGROUND

Whether iliac vein stents affect pregnancy or whether they will be affected by pregnancy was rarely reported in the literature. The aim of this study was to report our experience of pregnancy in women who received thrombolysis and stenting for a previous deep vein thrombosis (DVT).

METHODS

16 patients with previous stenting for treatment of acute left iliofemoral DVT who had subsequent pregnancies were identified. Patient demographic information and outcomes were recorded. Duplex scanning and venography were performed as scheduled to evaluate the patency of stents in perinatal period and at 12 months after delivery.

RESULTS

None of the patients had a hemorrhagic complication and recurrent venous thromboembolism during their pregnancies and postpartum. No stent compression/occlusion and structural damage occurrence in all patients during follow-up.

CONCLUSION

Pregnancy managed with prophylactic dalteparin resulted in no re-thrombotic events or structural damage to the iliac stents and did not appear to negatively affect pregnancy outcomes.

Outcomes of dedicated iliac venous stents during pregnancy and postpartum

OBJECTIVE

The aim of this study was to assess the performance of dedicated iliac venous stents during subsequent pregnancy and postpartum, including stent patency and stent integrity, as well as incidence of venous thromboembolism and bleeding complications.

METHODS

This study included retrospective analysis of prospectively collected data of patients attending a private vascular practice. Women of child-bearing age who had received dedicated iliac venous stents were included in a surveillance program and then, for any subsequent pregnancies, followed the same pregnancy care protocol. This included an antithrombotic regime of 100 mg aspirin daily until gestation week 36, and subcutaneous enoxaparin at a dose dependent on risk of thrombosis: low-risk patients, those stented for non-thrombotic iliac vein lesion, received a prophylactic dose of 40 mg/day from the third trimester; high-risk patients, those stented for thrombotic indication, received a therapeutic dose of 1.5 mg/kg/day from the first trimester. All women underwent follow-up with duplex ultrasound assessment of stent patency during pregnancy and at 6 weeks postpartum.

RESULTS

Data was analyzed for a total of 10 women and 13 post-stent pregnancies. Stents were placed for non-thrombotic iliac vein lesions in seven patients, and for post-thrombotic stenoses in three patients. All stents were dedicated venous stents, and four crossed the inguinal ligament. All stents remained patent during pregnancy, at 6 weeks postpartum, and latest follow-up (median time post-stent, 60 months). There were no cases of deep vein thrombosis or pulmonary embolism, and no bleeding complications. There was only one reintervention case due to in-stent thrombus, and one case of asymptomatic stent compression.

CONCLUSIONS

Dedicated venous stents performed well through pregnancy and post-partum. A protocol including the use of low dose antiplatelets in combination with anticoagulation at either a prophylactic or therapeutic dose depending on the patient's risk profile appears safe and effective.

Benchtop proof of concept and comparison of iron- and magnesium-based bioresorbable flow diverters

OBJECTIVE

Bioresorbable flow diverters (BRFDs) could significantly improve the performance of next-generation flow diverter technology. In the current work, magnesium and iron alloy BRFDs were prototyped and compared in terms of porosity/pore density, radial strength, flow diversion functionality, and resorption kinetics to offer insights into selecting the best available bioresorbable metal candidate for the BRFD application.

METHODS

BRFDs were constructed with braided wires made from alloys of magnesium (MgBRFD) or iron (FeBRFD). Pore density and crush resistance force were measured using established methods. BRFDs were deployed in silicone aneurysm models attached to flow loops to investigate flow diversion functionality and resorption kinetics in a simulated physiological environment.

RESULTS

The FeBRFD exhibited higher pore density (9.9 vs 4.3 pores/mm2) and crush resistance force (0.69 ± 0.05 vs 0.53 ± 0.05 N/cm, p = 0.0765, n = 3 per group) than the MgBRFD, although both crush resistances were within the range previously reported for FDA-approved flow diverters. The FeBRFD demonstrated greater flow diversion functionality than the MgBRFD, with significantly higher values of established flow diversion metrics (mean transit time 159.6 ± 11.9 vs 110.9 ± 1.6, p = 0.015; inverse washout slope 192.5 ± 9.0 vs 116.5 ± 1.5, p = 0.001; n = 3 per group; both metrics expressed as a percentage of the control condition). Last, the FeBRFD was able to maintain its braided structure for > 12 weeks, whereas the MgBRFD was almost completely resorbed after 5 weeks.

CONCLUSIONS

The results of this study demonstrated the ability to manufacture BRFDs with magnesium and iron alloys. The data suggest that the iron alloy is the superior material candidate for the BRFD application due to its higher mechanical strength and lower resorption rate relative to the magnesium alloy.

RETRACTED: Australian and New Zealand Society for Vascular Surgery clinical practice guidelines on venous outflow Obstruction of the femoral-iliocaval veins

BACKGROUND

The overall goal of this report is to provide a high-level, practical approach to managing venous outflow obstruction (VOO) in Australia and New Zealand.

METHODS

A group of vascular surgeons from the Australian and New Zealand Society for Vascular Surgery with specific interest, training, and experience in the management of VOO were surveyed to assess current local practice. The results were analyzed and areas of disagreement identified. Following this, the group performed a literature review of consensus guidelines published by leading international organizations focused on the management of chronic venous disease, namely the Society for Vascular Surgery, American Venous Forum, European Society for Vascular Surgery, American Vein and Lymphatic Society, Cardiovascular and Interventional Radiology Society of Europe, and American Heart Association. These guidelines were compared against the consensus statements obtained through the surveys to determine how they relate to Australian and New Zealand practice. In addition, selected key studies, reviews, and meta-analyses on venous stenting were discussed and added to the document. Finally, a selection of statements with >75% agreement was voted on, and barriers to the guideline's applicability were identified.

RESULTS

The document addresses two key areas: patient selection and technical aspects of venous stenting. Regarding patient selection, patients with a CEAP (Clinical-Etiologic-Anatomic-Physiologic) score of ≥3 or a venous clinical severity score for pain of ≥2, or both, and evidence of >50% stenosis on venography, computed tomography venography, magnetic resonance venography, and/or intravascular ultrasound should be considered for venous stenting (level of recommendation Ib) Patients undergoing thrombus removal for acute iliofemoral deep vein thrombosis, in whom a culprit stenotic lesion has been uncovered, should be considered for venous stenting (level of recommendation Ib). Patients with chronic pelvic pain, deep dyspareunia, postcoital pain affecting their quality of life, when other causes have been ruled out, should be considered for venous stenting (level of recommendation Ic). Asymptomatic patients should not be offered venous stenting (level of recommendation IIIc).

CONCLUSIONS

Patients with deep VOO have been underdiagnosed and undertreated for decades; however, in recent years, interest from physicians and industry has grown substantially. The advent of simpler and safer treatment options has revolutionized its management, but, unfortunately, formal training for venous disease has not grown at the same rate. Simplifying the technology and training required can result in inconsistent outcomes. These guidelines are aimed at developing standards of care and will serve as an educational platform for future developments.

Efficacy of closed cell self expandable metallic stent for peripheral arterial disease in the porcine iliac artery

This study aimed to investigate the efficacy of a closed-cell self-expandable metallic stent (SEMS) with or without expanded-polytetrafluoroethylene (e-PTFE)-covering membrane in a porcine iliac artery model. Twelve Yorkshire domestic pigs were divided into a bare closed-cell SEMS (B-SEMS) group (n = 6) and covered closed-cell SEMS (C-SEMS) group (n = 6). Both closed-cell SEMSs were placed in the right or left iliac artery. Thrombogenicity score in the C-SEMS group was significantly higher than that in the B-SEMS group (p = 0.004) after 4 weeks. Angiographic findings of mean luminal diameters at 4 weeks follow-up did not differ significantly between B-SEMS and C-SEMS groups. Neointimal hyperplasia thickness as well as degree of inflammatory cell infiltration and collagen deposition in the C-SEMS group was significantly greater than that in the B-SEMS group (p < 0.001). Closed-cell SEMSs successfully maintained patency for 4 weeks without stent-related complications in the porcine iliac artery. Although mild thrombus with neointimal hyperplasia was observed in the C-SEMS group, subsequent occlusion, and in-stent stenosis did not occur in any of the pigs until the end of the study. Closed-cell SEMS with or without the e-PTFE covering membrane is effective and safe for the porcine iliac artery.

Evaluation of safety and performance of a new prototype self-expandable nitinol venous stent in an ovine model

Objective

Our study was a prospective in vivo study performed on an animal model to evaluate the safety and performance of a novel venous stent designed specifically for venous applications.

Methods

The novel stents were implanted in the inferior vena cava of nine sheep. The stents were deployed with different distances between the closed cell rings to test for if the segments might migrate after being deployed at maximal distance. Three different total lengths were 9, 11, and 13 cm. After 1, 3, and 6 months, vascular injury, thrombus, neointima coverage, and stent migration were evaluated through computed tomography venography and histopathology. Imaging, histology, and integration data were analyzed for each group.

Results

All stents were deployed successfully, and all sheep survived until the time of harvesting. In all cases, the native blood vessel sections were intact. The segmented stent parts showed a differently pronounced tissue coverage, depending on the duration of the implantation.

Conclusions

The new nitinol stent is safe and feasible to implant in the venous system with a rapid surface coverage. Alteration of stent length did not affect the development of neointimal formation and did not cause migration.

How Controlled is the Expansion of VIATORR CX?

PURPOSE

To investigate and compare the physical properties of the new generation Gore VIATORR-Controlled Expansion Endoprosthesis (VCX) to those of the predecessor VIATORR stent in an in vitro experimental setup.

MATERIALS AND METHODS

A total of 12 stents (8 VCX; 4 VIATORR; GORE, USA) were examined. Radial resistive force (RRF) and chronic outward force (COF) were assessed using a radial force testing machine (RX-650, Machine Solutions Inc., USA). To assess the radial forces of the VCX above 8 mm, balloon expansion was performed between cycles.

RESULTS

All VCX stents show an abrupt decrease in COF at an external diameter of 8.3 mm; RRF decreases likewise at an external diameter of 8.5 mm. The predecessor VIATORR stent without the "controlled expansion" feature shows linear radial force reduction until full expansion at a diameter of 10 mm. The physical properties of the VCX can be altered by balloon modulation. Point of COF (RRF) reduction shifts to 8.5 mm (8.6 mm), 8.6 mm (8.8 mm) and 9.3 mm (9.6 mm) following modulation with a 8 mm, 9 mm and 10 mm balloon.

CONCLUSIONS

The VCX shows an abrupt and disproportionate decrease in COF and RRF at an external diameter of 8.3 mm, thus passive expansion to its nominal diameter of 10 mm is not to be expected. By means of balloon dilatation the physical properties of the stent can be altered, enabling customized TIPS creation. The previous VIATORR stent shows continuous COF and RRF until total expansion.

Computational modeling of braided venous stents - Effect of design features and device-tissue interaction on stent performance

Designing venous stents with desired properties is challenging due to the partly conflicting performance criteria, e.g., enhancing flexibility may be at odds with increasing patency. To evaluate the effect of design parameters on the mechanical performance of braided stents, computational simulations are performed using finite element analysis. Model validation is performed through comparison with measurements. Considered design features are stent length, wire diameter, pick rate, number of wires, and stent end-type, being either open-ended or closed looped. Based on the requirements of venous stents, tests are defined to study the effect of design variations with respect to the following key performance criteria: chronic outward force, crush resistance, conformability, and foreshortening. Computational modeling is demonstrated to be a valuable tool in the design process through its ability of assessing sensitivities of various performance metrics to the design parameters. Additionally, it is shown, using computational modeling, that the interaction between a braided stent and its surrounding anatomy has a significant impact on its performance. Therefore, taking into account device-tissue interaction is crucial for the proper assessment of stent performance.

Deep venous stenting in females

Deep venous stenting has gained increasing prominence in recent years. This issue focuses on special considerations in female patients. The specific challenge relates to the fact that these patients are often much younger than those in whom arterial stents are placed. The stents have to perform adequately over potentially 60 years- and there is no data of that length available.

Systematic review of endovascular versus laparoscopic extravascular stenting for treatment of nutcracker syndrome

OBJECTIVE

The aim of the present study was to assess the current strategies of endovascular and laparoscopic extravascular stenting for symptomatic compression of the left renal vein (LRV), most frequently between the aorta and superior mesenteric artery (nutcracker syndrome [NCS]).

METHODS

We performed a systematic review of all studies of endovascular and laparoscopic extravascular LRV stenting for NCS using the PubMed/MEDLINE, Scopus, Embase, Cochrane, Science Citation Index Expanded, Emerging Sources Citation Index, and Epistemonikos databases. Data were collected in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analysis) guidelines. The English, Spanish, and German language literature was searched from January 1, 1946 to February 9, 2022. The outcomes assessed included symptom resolution, hematuria resolution, and reintervention at follow-up.

RESULTS

The search yielded 3498 reports. After removing the duplicates and those without the full text available, 1724 studies were screened. Of these, 11 studies were included in the present review. Of the 11 studies, 7 were on endovascular stenting and 4 on laparoscopic extravascular stenting; all 11 studies were retrospective, single-center case series. Of the 233 patients, 170 (80 women) had undergone endovascular stenting and 63 (9 women) had undergone extravascular stenting. The follow-up period varied from 1 to 60 months after endovascular stenting and 3 to 55 months after extravascular stenting. The symptoms had resolved in 76% (range, 50%-100%) after endovascular stenting and 83% (range, 71%-100%) after extravascular stenting. Hematuria had resolved in 86% (range, 60%-100%) after endovascular stenting and 89% (range, 77%-100%) after extravascular stenting. Of 185 patients, 9 had required reintervention after endovascular stenting and none after extravascular stenting.

CONCLUSIONS

Endovascular and laparoscopic extravascular stenting are less invasive and, thus, more attractive treatment options that have been more recently developed for the management of NCS. The results from the present study have shown that symptom and hematuria resolution must be provided before they can be considered preferred management options for patients affected by NCS. Given the limited number of patients involved, no definitive conclusion could be drawn regarding the superiority of one technique compared with the other.

A practice audit of short-term outcomes of Wallstents versus Venovo stents for the treatment of nonthrombotic iliac vein outflow stenoses

OBJECTIVE

The Wallstent (WS; Boston Scientific, Malborough, MA) is currently the standard of care for comparisons of clinical efficacy for new stent devices in the treatment of iliac vein outflow disease. Many vein-specific Nitinol-based stents have been now approved by the Food and Drug Administration for use in the iliofemoral venous system. However, few comparisons of these devices to the current standard have been reported. The purpose of this investigation was to compare the complication and reintervention rates between the WS and Venovo stent (VS; BD, Franklin Lakes, NJ).

METHODS

A random sample of 100 WS and 100 VS cases performed from April 2018 through December 2020 were selected for retrospective analysis. The demographics, presenting symptoms, and CEAP (Clinical, Etiology, Anatomy, Pathophysiology) class were assessed. The complication logs and 90-day follow-up data were reviewed for every case to assess the incidence of postoperative deep vein thrombosis, stent thrombosis, in-stent restenosis, bleeding, and transient back pain.

RESULTS

WSs had been placed more often in the left common iliac vein segment (52 vs 1), and VSs had been placed more often in the left common iliac vein and external iliac vein segments (36 vs 63; P = .0069). The average diameter and length of the WSs and VSs were 19.7 ± 2.2 mm vs 15 ± 1.4 mm (P = 2.4∗10^-44) and 80.8 ± 9 mm vs 117.6 ± 20.4 mm (P = 2.4∗10^-38), respectively. The average number of stents per patient was 1.05 for the WSs and 1.03 for the VSs (P = .47). The reintervention rates were similar between the two groups: WS, n = 5; and VS, n = 4 (P = .74). Four of the five WS reinterventions were stent extensions to treat in-stent restenosis and recurrence of symptoms, and one was secondary to occlusion requiring ipsilateral venoplasty and stenting. Two of the four VS reinterventions were venoplasty for in-stent restenosis and two were stent extensions for symptom recurrence. Transient back pain was the most common complication (WS, 37%; VS, 47%; P = 0.28). Insertion site deep vein thrombosis had developed in the three patients in the WS group and four patients in the VS group (P = .71). No patient had experienced bleeding requiring hospitalization, and no stent fractures, stent migration, or deaths had occurred.

CONCLUSIONS

The complication and reintervention rates between the WS and VS groups were similar. Both stents demonstrated evidence of in-stent stenosis requiring reintervention. Implanted VSs tended to be smaller in diameter and longer in length and covered the common and external iliac veins more often compared with the WSs. Therefore, one VS can be used to cover two territories compared with the WS for which two stents will be required to cover the same vein territory length.

Technique of stent sizing in patients with symptomatic chronic iliofemoral venous obstruction-the case for intravascular ultrasound-determined inflow channel luminal area-based stenting and associated long-term outcomes

OBJECTIVE

Femoroiliocaval stenting has become the standard of care for patients with quality-of-life impairing chronic iliofemoral venous obstruction not responding to conservative measures. Although improvement after stenting has been noted in multiple large studies, sizing of stents has been subjective in nature with a general tendency to use smaller stents that would be required to relieve venous hypertension. This study evaluates the authors' technique of using the intravascular ultrasound (IVUS) inflow channel luminal area to guide stent sizing.

METHODS

Patients who underwent femoroiliocaval stenting for quality-of-life impairing chronic iliofemoral venous obstruction and had failed conservative therapy from 2015 to 2021 were included in the study. Clinical outcomes including venous clinical severity score (VCSS), visual analog scale (VAS) pain score, and grade of swelling (GOS) were appraised before and after stenting. Also evaluated were quality of life (Chronic Venous Insufficiency Questionnaire-20 [CIVIQ-20] instrument) and stent outcomes including patencies and reinterventions. Comparisons were made between limbs that underwent placement of larger caliber stents (largest stent diameter >20 mm: >20 mm stent group) vs smaller caliber stents (largest stent diameter ≤20 mm: ≤20 mm stent group). t tests and analysis of variance were used to compare outcomes, whereas the Kaplan-Meier analysis was used to evaluate patencies with log rank used to compare the curves.

RESULTS

A total of 300 patients (300 limbs) underwent stenting with a median age of 58 years. There was a preponderance of men (159 of 300), left laterality (176 of 300), and post-thrombotic syndrome (176 of 300). The median body mass index was 41. There were 120 limbs in the >20 mm stent group and 180 limbs in the ≤20 mm stent group. The median follow-up was 23 months. There was no significant difference in baseline VCSS, VAS pain score, or GOS between the two groups. However, there was a significant difference in IVUS-determined inflow channel luminal area between the two groups (228 mm² >20 mm stent group vs 176 mm² for ≤20 mm stent group [P < .0001]). After stenting there was a significant improvement in the VCSS, VAS pain score, and GOS at 6 weeks, 3, 6, 12, and 24 months (P < .0001) without any difference between the groups (P > .05). The CIVIQ-20 score also improved from 58 to 38 (P < .0001) for the entire cohort and for the two groups (P < .0001). Overall primary, primary-assisted, and secondary patencies at 60 months were 84%, 100%, and 100%, respectively. Reintervention rate was 10% without any difference between the groups.

CONCLUSIONS

Stent sizing using IVUS-determined inflow channel luminal area in patients undergoing stenting for quality-of-life impairing chronic iliofemoral venous obstruction resulted in a significant improvement in the VCSS, VAS pain score, GOS, and quality of life (CIVIQ-20) after stenting. Excellent stent patencies and low reintervention rates were also noted. IVUS-determined inflow channel luminal area represents an objective technique of stent sizing in comparison to the subjective techniques that currently exist.

Medium Term Outcomes of Deep Venous Stenting in the Management of Venous Thoracic Outlet Syndrome

OBJECTIVE

Venous thoracic outlet syndrome (vTOS) is a relatively rare condition associated with significant morbidity. Its management continues to evolve, with increasing use of endovascular adjuncts, such as percutaneous thrombectomy and angioplasty, in addition to first rib resection. The utility of stenting residual venous stenotic lesions is poorly defined within the literature. This study sought to review the medium term patency rates of upper limb deep venous stenting in the management of vTOS.

METHODS

A single centre, retrospective review of patients managed for vTOS with first rib resection followed by upper limb deep venous stenting between January 2012 and February 2021 was conducted. Post-procedural ultrasounds were reviewed to determine stent patency.

RESULTS

Twenty-six patients were included, with 33 stents placed. The median duration of follow up was 50 months. On venous duplex ultrasound at three years post-operatively, primary patency rates were 66%, primary assisted patency rates were 88%, secondary patency rates were 91%, and total occlusion rates were 9%. After stent placement, 80% of patients remained asymptomatic with regard to compression symptoms.

CONCLUSION

Upper limb deep venous stenting is an effective adjunct to surgical decompression in the management of vTOS. Stent medium term patency rates are promising; however, further studies with longer follow up and larger cohorts with multicentre results are required to confirm these early findings.

Iliofemoral venous configurations from three-dimensional computed tomography venogram and their relevance to stent design

OBJECTIVE

Iliofemoral venous stenting has become the standard of care for patients presenting with quality-of-life impairing symptoms of chronic iliofemoral venous obstruction not responding to conservative measures. This has led to an increased use of venous stenting over the last several years. However, iliofemoral venous anatomy in patients requiring such intervention remains poorly elucidated. This study attempts to fill that gap.

METHODS

Twenty-two consecutive patients with intravascular ultrasound examination-confirmed chronic iliofemoral venous obstruction underwent three-dimensional reconstruction of their computed tomography venogram images. Relevant angles, tortuosity (tort index-ratio between centerline length, and straight line length), lengths, and diameters were computed and analyzed. We used t tests for comparisons between the right and left sides. A P value of .05 or less was considered significant.

RESULTS

Of the angles calculated, the median of the angles between the horizontal and common iliac vein (CIV) was 66° on the right and 60° on the left (P < .01). The median inferior vena cava-CIV angle was 172° on the right and 165° on the left (P < .0001). The CIV-EIV angle was 159° on the right and 151° on the L (P = .01). Overall, the median tortuosity was 1.07 on the right and 1.12 on the left (P = .007). The median centerline length of the CIV was 42mm on the right and 60mm on the left (P < .0001). The median external iliac vein length was 73 mm on the right and 88 mm on the left (P < .0001). The overall median iliac vein length was 220 mm on the right and 237 mm on the left (P < .01). The median diameters of the inferior vena cava at the iliocaval confluence, 20, 40, and 60 mm cranial to the confluence, were 23, 20, 22, and 23 mm, respectively.

CONCLUSIONS

Overall, the left side has steeper angles, greater tortuosity, and longer lengths than the right side. These disparities should be considered during femoroiliocaval stent construction.

The Clinical Problem of Pelvic Venous Disorders

Pelvic venous disorders are inter-related pathologic conditions caused by reflux and obstruction in the pelvic veins. It can present a spectrum of clinical features based on the route of transmission of venous hypertension to either distal or caudal venous reservoirs. Imaging can help to visualize pelvic vascular and visceral structures to rule out other gynecologic, gastrointestinal, and urologic diseases. Endovascular treatment, owing to its low invasive nature and high success rate, has become the mainstay in the management of pelvic venous disorders. This article reviews the pathophysiology, clinical presentations, and diagnostic and therapeutic approaches to pelvic venous disorders.

Clinical outcomes and overview of dedicated venous stents for management of chronic iliocaval and femoral deep venous disease

OBJECTIVES

Venous stenting of the lower extremities has grown in popularity and is now considered a key component of the primary treatment strategy for the management of pathologically obstructive or stenotic lesions of the deep venous system. This review aims to provide an overview of the role of venous stenting in the management of chronic conditions affecting the deep venous system of the lower limbs.

METHODS

An overview of venous stents design and current role of stenting procedure in individuals presenting with Chronic Venous Insufficiency (CVI) and presenting the current trials of dedicated venous stenting in management of chronic deep venous lesions. This review provides a focused insight on venous stent design, physical properties and the available dedicated venous stents selected studies with their related patency outcome based on selective literature search of the PubMed database and Cochrane library.

CONCLUSIONS

Dedicated venous stent technology is advancing at a rapid pace alongside the increased undertaking of endovascular deep venous stent reconstruction in the management of iliocaval vein pathologies. The ideal design(s) for venous stents remain unknown, although it is hoped that the presence of new dedicated venous stents in clinical practice will allow the generation of experience and data to advance our understanding in this area.

Mechanical characteristics of venous stents to overcome challenges of venous outflow obstruction

BACKGROUND

Many challenges posed by the venous outflow obstruction (VOO) are unique to the venous system which require specific mechanical characteristics of stents to overcome them. Therefore, this article aims to review and discuss these challenges and the stent mechanical characteristics required to overcome them.

METHODS

A literature search was performed with Pubmed with the terms "mechanical characteristics of venous stents" and "mechanical properties of venous stents".

RESULTS

The venous system poses unique anatomical, physiological and pathological challenges when compared to the arterial counterpart. Several mechanical characteristics specific to venous stents which include the size, inherent forces, and flexibility are important to overcome these unique challenges when treating VOO. The most important stent inherent forces for venous stents include the chronic outward force, radial resistive force, and crush resistance. Various stent materials and designs, particularly laser-cut versus braided-structure stents, and open-cell versus closed-cell stents, determine the mechanical characteristics including the inherent forces of the venous stents. The desired mechanical characteristics of stents needed to overcome the venous system challenges often in conflict or with opposing effects. Therefore, it is important to fine adjust and optimise these characteristics.

CONCLUSIONS

There are many anatomical, physiological, and pathological challenges unique to the venous system which need to be overcome by the stent system mechanically when treating VOO. Therefore, dedicated venous stents with optimal mechanical characteristics are being developed with different designs and properties to treat VOO. Further research and innovations are needed to improve the stent technology that targets the venous system specifically.

Pivotal Study Evaluating the Safety and Effectiveness of the Abre Venous Self-Expanding Stent System in Patients With Symptomatic Iliofemoral Venous Outflow Obstruction

Supplemental Digital Content is available in the text.

Background:

Iliofemoral venous obstruction is recognized with increasing frequency as the underlying cause of lower extremity symptoms including edema, pain, skin changes, and, in advanced cases, ulceration. This study sought to evaluate the safety and effectiveness of the Abre venous self-expanding stent system for the treatment of symptomatic iliofemoral venous outflow obstruction.

Methods:

The ABRE Study (A Multi-Center, Non-Randomized Study to Evaluate the Safety and Effectiveness of the Abre Venous Self-Expanding Stent System in Patients With Symptomatic Iliofemoral Venous Outflow Obstruction) is a single-arm, multicenter, prospective study that included 200 subjects from 24 global sites. The primary end points were 12-month primary patency and major adverse events within 30 days. Secondary end points included lesion and procedure success, primary-assisted and secondary patency, major adverse events, stent migration, stent fracture, and quality of life changes. End point-related adverse events and imaging studies were adjudicated by independent clinical events committee and core laboratories, respectively.

Results:

Venous obstruction cause was classified as acute deep vein thrombosis (16.5%, 33/200), post-thrombotic syndrome (47.5%, 95/200), or nonthrombotic iliac vein lesion (36.0%, 72/200). The common iliac and external iliac veins were stented in 96.0% (192/200), 80.5% (161/200) of subjects, respectively. Stent implant into the common femoral vein was required in 44.0% (88/200). Primary patency at 12 months was 88.0% (162/184). Four (2.0%) major adverse events occurred within 30 days. Twelve-month primary-assisted and secondary patency were 91.8% (169/184) and 92.9% (171/184), respectively. No stent fractures or migrations were reported. Mean target limb Villalta score decreased from 11.2±5.6 at baseline to 4.1±4.8 at 12 months, and the mean target limb revised Venous Clinical Severity Score decreased from 8.8±4.7 at baseline to 4.3±3.6 at 12 months. Clinically meaningful improvements in quality of life and venous functional assessment scores from baseline were demonstrated through 12 months in all measures.

Conclusions:

Symptomatic iliofemoral venous obstruction can be successfully treated with an Abre venous stent. Study outcomes demonstrated a high patency rate with a good safety profile. Patients demonstrated a significant reduction in clinical symptoms and improvement in quality of life that was maintained through 12-month follow-up.

Registration:

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03038438.

Venous stent versus conventional stent for the treatment of central vein obstruction in hemodialysis patients: a retrospective study

BACKGROUND

Endovascular treatment is a first-line treatment for upper thoracic central vein obstruction (CVO). Few studies using bare venous stents (BVS) in CVO have been conducted.

PURPOSE

To evaluate the treatment performance of upper thoracic central vein stenosis between BVS and conventional bare stent (CBS) in hemodialysis patients.

METHODS

Hemodialysis patients with upper thoracic central vein obstruction who underwent endovascular treatment at the interventional unit of our institution from 1 January 2008 to 31 December 2018 were enrolled in the present study. CBS was used to treat central vein obstruction in 43 patients and BVS in 34 patients. We compared the primary patency rates and complications between the two stent types. P values < 0.05 were considered statistically significant.

RESULTS

The patient demographic data between the CBS and BVS groups were similar. The characteristics of the lesions, procedures, and complications were not significantly different between the two groups (P > 0.05). There were no statistically significant differences of primary patency rates at three and six months between the BVS and CBS groups (94.1% vs. 86.0% and 73.5% vs. 58.1%, respectively; P > 0.05). The primary patency rate at 12 months in the BVS group was significantly higher than that in the CBS group (61.8% vs. 32.6%; P = 0.008).

CONCLUSION

Endovascular treatment of central vein obstruction with BVS provided a higher primary patency rate at 12 months than CBS.

Endovascular Venous Stenosis and Thrombosis Large Animal Model: angiographic, histological, and biomechanical characterization

PURPOSE

Characterize an ovine endovascular radiofrequency ablation based venous stenosis and thrombosis model for studying venous biomechanics and response to intervention.

MATERIALS AND METHODS

Unilateral short-segment (n= 2) or long-segment (n = 6) iliac vein stenoses were created in eight adult sheep using an endovenous radiofrequency (RF) ablation technique. Angiographic assessment was performed at baseline, immediately after venous stenosis creation, and after 2-week (n = 6) or 3-month (n = 2) survival. Stenosed iliac veins and contralateral healthy controls were harvested for histological and biomechanical assessment.

RESULTS

At follow-up, the short-segment RF ablation group showed stable stenosis without occlusion. The long-segment group showed complete venous occlusion/thrombosis with formation of collateral veins. Stenosed veins showed significant wall thickening (0.28 mm vs 0.16 mm; p = 0.0175) and confluent collagen deposition compared to healthy controls. Subacute non-adherent thrombi were apparent at 2 weeks, which were replaced by fibrous luminal obliteration with channels of recanalization at 3 months. Stenosed veins demonstrated increased longitudinal stiffness (448.5 ± 5.4 kPa vs. 314.6 ± 1.5 kPa, p < 0.0001) and decreased circumferential stiffness (140.8 ± 2.6 kPa vs. 246.0 ± 1.6 kPa, p < 0.0001) compared to healthy controls.

CONCLUSION

Endovenous radiofrequency ablation is a reliable technique for creating venous stenosis and thrombosis in a large animal model with histological and biomechanical attributes similar to those seen in humans. This platform can facilitate understanding of venous biomechanics and testing of venous specific devices and interventions.

Reconstruction of an inferior vena cava stent occlusion using double-barrel stenting in a patient with Behçet's disease

Symptomatic inferior vena cava (IVC) and iliac vein thrombosis is increasingly being treated with thrombolysis, thrombus retrieval and deep venous stenting. If the IVC stent occludes, endovenous intervention is indicated to restore patency. An 18-year-old male with Behçet's disease presented with deep vein thrombosis (extending from the IVC to the popliteal segments bilaterally) which was initially treated with thrombolysis and stenting. Fifteen months later, the patient experienced symptomatic deterioration; a chronically-occluded IVC stent was identified and reconstructed using a double-barrel stenting technique. Patient compliance to post-stenting anticoagulation therapy is paramount to maintain stent patency. A multi-disciplinary approach including haematologists can be beneficial for patients with a background of thrombophilic disorders.

Three-Year Results from the Venovo Venous Stent Study for the Treatment of Iliac and Femoral Vein Obstruction

Purpose

To assess safety and patency of the Venovo venous stent for the treatment of iliofemoral vein obstruction.

Materials and Methods

Twenty-two international centers enrolled 170 patients in the VERNACULAR study (93 post-thrombotic syndrome; 77 non-thrombotic iliac vein lesions). Primary outcome measures were major adverse events at 30 days and 12-month primary patency (freedom from target vessel revascularization, thrombotic occlusion, or stenosis > 50%). Secondary outcomes included the Venous Clinical Severity Score Pain Assessment and Chronic Venous Quality-of-Life Questionnaire assessments (hypothesis tested). Secondary observations included primary patency, target vessel and lesion revascularization (TVR/TLR), and assessment of stent integrity through 36 months.

Results

Freedom from major adverse events through 30 days was 93.5%, statistically higher than a pre-specified performance goal of 89% (p = 0.032) while primary patency at 12 months was 88.6%, also statistically higher than a performance goal of 74% (p < 0.0001). Mean quality-of-life measures were statistically improved compared to baseline values at 12 months (p < 0.0001). Primary patency at 36 months was 84% (Kaplan–Meier analysis) while freedom from TVR/TLR was 88.1%. There was no stent embolization/migration, and no core laboratory assessed stent fractures reported through 36 months. Six deaths were reported; none adjudicated as device or procedure related.

Conclusion

The Venovo venous stent was successfully deployed in obstructive iliofemoral vein lesions and met the pre-specified primary outcome measures through 12 months. At 3 years, primary patency was 84%, reintervention rates were low, standardized quality-of-life and pain measures improved from baseline, and there was no stent migration or fractures.

Level of Evidence

Level 2—prospective, multicenter, controlled clinical study without a concurrent control or randomization. Pre-specified endpoints were hypothesis-tested to performance goals derived from peer-reviewed clinical literature.

Registration clinicaltrials.gov

Unique Identifier NCT02655887.

What are the ideal characteristics of a venous stent?

Historically, the stents used in the venous system were not dedicated scaffolds. They were largely adapted arterial stents. An essential feature of a venous stent is compliance, in order to adapt its crosssectional area to the vein. It should also be crush resistant, corrosion resistant and fatigue resistant. The material should be radiopaque, for follow-up. Another characteristic of the ideal venous stent is flexibility, to adapt its shape to the vein, not vice versa. The scaffold should be uncovered too, in order to avoid the occlusion of collaterals. The ideal venous stent should not migrate, so it is necessary a large diameter and a long length. The radial force is important to prevent migration. However, current stents derived from arterial use display high radial force, which could affect the patency of the thin venous wall. Alternatively, if the stent has an anchor point, that permits a passive anchoring, the radial force required to avoid migration will be lower. Dedicated venous stents were not available until very recently. Furthermore, there is a preclinical study about a new compliant nitinol stent, denominated Petalo CVS. Out of the commonest causes of large veins obstruction, dedicated venous stent could also treat other diseases described more recently, such as the jugular variant of the Eagle syndrome, JEDI syndrome and jugular lesions of the chronic cerebrospinal venous insufficiency that result unfavorable for angioplasty according to Giaquinta classification.

Artifact quantification of venous stents in the MRI environment: Differences between braided and laser-cut designs

PURPOSE

To quantify B₀- and B₁-induced imaging artifacts of braided venous stents and to compare the artifacts to a set of laser-cut stents used in venous interventions.

METHODS

Three prototypes of braided venous stents with different geometries were tested in vitro. B₀ field distortion maps were measured via the frequency shift Δf using multi-echo imaging. B₁ distortions were quantified using the double angle method. The relative amplitudes B₁^rel were calculated to compare the intraluminal alteration of B₁. Measurements were repeated with the stents in three different orientations: parallel, diagonal and orthogonal to B₀.

RESULTS

At 1.5 T, the braided stents induced a maximum frequency shift of Δfx<100Hz. Signal voids were limited to a distance of 2 mm to the stent walls at an echo time of 3 ms. No substantial difference in the B₀ field distortions was seen between laser-cut and braided venous stents. B₁^rel maps showed strongly varying distortion patterns in the braided stents with the mean intraluminal B₁^rel ranging from 63±18% in prototype 1 to 98±38% in prototype 2. Compared to laser-cut stents the braided stents showed a 5 to 9 times higher coefficient of variation of the intraluminal B₁^rel.

CONCLUSION

Braided venous stent prototypes allow for MR imaging of the intraluminal area without substantial signal voids due to B₀-induced artifacts. Whereas B₁ is attenuated homogeneously in laser-cut stents, the B₁ distortion in braided stents is more inhomogeneous and shows areas with enhanced amplitude. This could potentially be used in braided stent designs for intraluminal signal amplification.

Transient arterial insufficiency and neurologic deficit following external iliac vein stent reconstruction for malignant compression

Acute iliofemoral deep vein thrombosis may present with pain and swelling or phlegmasia cerulea dolens. When thrombosis occurs in the setting of an underlying venous obstruction, stent reconstruction should be performed after thrombus clearance to prevent rethrombosis. Stent reconstruction after thrombus clearance is associated with high technical success rates and durable patency. This report describes transient lower extremity arterial insufficiency and neurologic deficit after external iliac vein stent expansion and reconstruction within a confined space resulting from a malignant obstruction. It serves as a cautionary tale that, in rare cases, aggressive venous stenting within a confined space can transfer clinically significant forces to adjacent arteries and nerves.

A clinical guide to Deep venous stenting for chronic iliofemoral venous obstruction

INTRODUCTION

An increase in endovenous interventions for deep venous pathologies has been observed. This article aims to provide an overview of the role of venous stenting in the management of chronic conditions affecting the deep venous system of the lower limbs, with a focus on intervention relating to the vena cava and iliofemoral venous segments.

METHOD

An overview of the literature on the minimally invasive venous stenting procedures that are being increasingly used in the management of chronic conditions affecting the deep venous system of the lower limbs.

RESULTS

We discuss key areas of interest to a venous specialist practicing in this area, including diagnostic imaging in chronic deep venous disease, with a focus on the use of intravascular ultrasound in this context; treatment of chronic venous outflow obstruction, including the rationale and structural indications for stenting, current guidance regarding stent placement, and fundamental points to consider during decision-making (endophlebectomy and stenting, stenting across the inguinal ligament, optimal sizing of venous stents, extension of venous stenting to beyond the common femoral vein confluence, the role of thrombolysis useful in chronic venous disease, and arteriovenous fistulae); outcomes and initial reports of stenting; and the future of venous stents.

CONCLUSION

Deep venous stenting has become a key treatment option for chronic (thrombotic or non-thrombotic) obstructive venous disease. Dedicated venous stents and intravascular ultrasound represent important technological advances in the minimally invasive treatment of symptomatic chronic deep venous obstruction, which previously required open surgical reconstruction.