Pivotal Evaluation of Novel Dedicated Venous Stent for Iliofemoral Venous Obstruction: A Prospective Cohort Study.

PURPOSE: The purpose was to evaluate the clinical outcomes of a dedicated venous stent with the tripartite composite segments for the treatment of iliofemoral venous obstruction (IVO) in a mixed cohort of nonthrombotic iliac vein lesion (NIVL) and post-thrombotic syndrome (PTS) over a period of 12 months. METHODS: The Grency Trial is a prospective, multicenter, single-arm, open-label, pivotal study, which was conducted at 18 large tertiary hospitals in China from August 2019 to October 2020. A total of 133 hospitalized patients were screened and 110 patients with clinical, etiology, anatomical, and pathophysiology clinical class (CEAP) clinical grade C>3 and iliac vein stenosis >50% or occlusion, including 72 patients with NIVL and 38 patients with PTS, were implanted with Grency venous stents. Primary endpoint was stent patency at 12 months follow-up, and secondary outcomes were technical success; improvement in venous clinical severity score (VCSS) at 3, 6, and 12 month follow-up; and rates of clinical adverse events. RESULTS: Among 110 patients who were implanted with Grency venous stents, 107 patients completed the 12 month follow-up. All 129 stents were successfully implanted in 110 limbs. Twelve-month primary patency rate was 94.39% [95% confidence interval [CI]=88.19%-97.91%] overall, and 100% [94.94%-100%] and 83.33% [67.19%-93.63%] in the NIVL and PTS subgroups, respectively. Venous clinical severity score after iliac vein stenting improved significantly up to 12 months follow-up. There were 3 early major adverse events (1 intracerebral hemorrhage and 2 stent thrombosis events related to anticoagulation therapy), and 7 late major adverse events (1 cardiovascular death, 1 intracranial hemorrhage with uncontrolled hypertension, and 5 in-stent restenosis cases without stent fractures or migration). CONCLUSIONS: The Grency venous stent system appeared excellent preliminary safe and effective for IVO treatment. Further large-scale studies with longer-term follow-up are needed to evaluate long-term patency and durability of stent. CLINICAL IMPACT: The design of venous stents for iliofemoral venous obstruction (IVO) must address engineering challenges distinct from those encountered in arterial stenting. The Grency venous stent, a nitinol self-expanding stent specifically tailored for IVO, features a composite structure designed to meet the stent requirements of various iliac vein segments. The Grency Trial is a prospective, multicenter, single-arm, open-label pivotal study aimed at evaluating the efficacy and safety of the Grency stent system. Following a 12-month follow-up period, the Grency venous stent system has demonstrated both safety and efficacy in treating iliofemoral venous outflow obstruction.

Rescue From Permanent Kidney Injury in Acute Thrombosis of Both Renal Veins, the Inferior Vena Cava, and Both Iliofemoral Veins by Catheter-Based Thrombectomy.

CASE: A 33-year-old man with previously diagnosed lupus membranous nephropathy presented with painful swelling in both legs. Laboratory tests revealed acute kidney injury, and imaging studies by duplex ultrasound and computed tomography scan showed acute thrombosis of both renal veins, the infrahepatic inferior vena cava, and both iliofemoral venous segments. Initially, pharmacomechanical thrombolysis led to an insufficient morphological result. The therapeutic breakthrough was achieved by catheter-based mechanical thrombectomy of the infrarenal vena cava and both renal veins, which successfully cleared all affected venous segments from thrombus, paralleled by improvement of the patient's condition. However, after 1 week, the patient experienced recurrent thrombosis of the right renal vein with hemorrhagic infarction of the right kidney. After further optimization of immunomodulatory and antithrombotic therapy, a repeated catheter-based mechanical thrombectomy resulted in sustained clinical improvement and preservation of renal venous drainage and kidney function. CONCLUSION: Extensive acute thrombosis of both renal veins, the inferior vena cava, and both iliofemoral venous segments is a rare emergency potentially threatening kidney function. Immediate effective thrombus removal is essential to preserve kidney function and can be achieved by catheter-based mechanical thrombectomy embedded in a comprehensive immunomodulatory and antithrombotic therapeutic concept. CLINICAL IMPACT: This case demonstrated the efficacy of a catheter-based therapeutic approach in patients with extensive thrombosis of the venous system. A catheter-based approach must be embedded in a comprehensive medical therapeutic concept, which is essential to achieve a sustainable result.

Editor's Choice - Management of Lower Extremity Venous Outflow Obstruction: Results of an International Delphi Consensus.

OBJECTIVE: The endovascular treatment of venous obstruction has expanded significantly in recent years. Best practices for optimal patient outcomes are not well established and the evidence base is poor. The purpose of this study was to obtain consensus on management criteria for patients with lower extremity venous outflow obstruction. METHODS: The study was conducted as a two round Delphi consensus. Statements addressed imaging, symptoms and other baseline measures, differential diagnosis, treatment algorithm, indications for stenting, inflow and outflow assessment, successful procedural outcomes, post-procedure therapies and stent surveillance, and clinical success factors. Statements were prepared by six expert physicians (round 1, 40 statements) and an expanded panel of 24 physicians (round 2, 80 statements) and sent to a pre-identified group of venous experts who met qualifying criteria. A 9 point Likert scale was used and consensus was defined as ≥ 70% of respondents rating a statement between 7 and 9 (agreement) or between 1 and 3 (disagreement). Round 1 results were used to guide rewording and splitting compound statements for greater clarity in round 2. RESULTS: In round 1, 75 of 110 (68%) experts responded, and 91 of 121 (75%) experts responded in round 2. Round 1 achieved consensus in 32/40 (80%) statements. Consensus was not reached in the treatment algorithm section. Round 2 achieved consensus in 50/80 (62.5%). Statements reaching consensus were imaging (2/3, 66%), symptoms and other baseline measures (12/24, 50%), differential diagnosis (2/8, 25%), treatment algorithm (10/17, 59%), indications for stenting (10/10, 100%), inflow and outflow assessment (2/2, 100%), procedural outcomes (2/2, 100%), post-procedure therapies and stent surveillance, (5/7, 71%), and clinical success factors (5/7, 71%). CONCLUSION: This study demonstrated that considerable consensus was achieved between venous experts on the optimal management of lower extremity venous outflow obstruction. There were multiple domains where consensus is lacking, highlighting important areas for further investigation and research.

Fatigue Test Method to Evaluate the 50 Year Durability of Venous Stents.

OBJECTIVE: Iliofemoral venous obstructive disease can result in significant, potentially debilitating symptoms that can negatively affect quality of life. Unlike arterial disease, patients with deep venous disease have a significantly lower median age, therefore the need for long term stent patency becomes a matter of decades rather than years. Furthermore, iliofemoral lesions frequently require stent placement across the inguinal ligament. Such stents are subject to dynamic stress from leg movement and associated concerns for device fatigue, resulting in stent fracture. The aim of this study was to describe an in vitro 50 year stent fatigue test method designed to assess durability against dynamic stress induced device fracture. METHODS: Through literature review, cadaver studies, and computer modelling, the most challenging loading was confirmed to be hip flexion across the inguinal ligament. This occurs when the patient adjusts between a seated and standing position. Sit to stand hip flexion at the inguinal ligament was effectively simulated on the bench in this in vitro experimental study. RESULTS: When tested under challenge parameters, hip flexion was reliably found to cause fractures in non-venous nitinol stents. However, a dedicated self expanding nitinol venous stent, engineered for improved durability, underwent up to 50 years of simulated loading on the bench with 15% (3/20) of stents experiencing fractures at 50 years, compared with fractures in 35% (14/40) of non-venous stents tested to 1.4 years; no statistical testing was performed as durations do not match and the objective was to demonstrate the test method. CONCLUSION: The presented fatigue test method is a suitable approach for evaluating the durability of stents intended for venous use. Venous stents demonstrated superior fatigue resistance compared with non-venous stents via in vitro hip flexion testing.

Expansion of WallStents® After Initial Deployment in Nonthrombotic Iliac Vein Lesions.

OBJECTIVE: To determine the structural changes of Wallstents® (Boston Scientific, Natick, MA) in vivo following deployment in iliac veins. METHODS: This retrospective single-center study was performed from September 2012 to April 2013 and included 100 office-based patients who underwent initial stent placement for nonthrombotic iliac vein lesions with Wallstent® as well as a second procedure for stenting of the contralateral iliac vein. Measurements were obtained with marker balloons and the diameters of the stents were compared at the time of the index procedure to the secondary procedure. RESULTS: The average time between the two procedures was 28 days (range 3-237, SD ± 39.89). The overall average stent diameter after the index procedure was 16.38 mm (range 10.95-21.45, SD ± 2.24). The overall average stent diameter of the index stent when remeasured during the second intervention was 17.58 mm (range 12.84-24.11, SD ± 2.38, p=0.0003) which was significantly different from the initial measurements. There was no difference when comparing changes in stent diameter by gender or laterality of procedure. However, there was a significant difference in expansion of stents when placed in the common iliac vein vs the external iliac or common femoral veins. CONCLUSIONS: This study shows that self-expanding Wallstents® can continue to expand days to weeks in vivo following initial deployment. Additionally, we found that the change in diameter from initial placement to follow up was more significant in stents placed in the proximal and middle segments of the common iliac vein. CLINICAL RELEVANCE: Wallstents® are durable implants designed to last within a patient for the rest of their life, it is important to understand the structural changes occurring after their placement. This study allows for a better understanding of Wallstent® dynamics in vivo.

The Pulsating Stent Sign in May-Thurner Syndrome.

PURPOSE: To report a case of a patient with May-Thurner syndrome who underwent endovenous stenting and was found to have pulsating arterial compression on the venous stent. REPORT: A 74-year-old man presented with 18 months of progressive right thigh and calf edema. After an extensive work-up, the patient underwent a venogram with intravascular ultrasound (IVUS), revealing compression of the right iliac vein by the external iliac artery and psoas muscle. Following stent deployment, fluoroscopy revealed extrinsic compression by an artery, but IVUS confirmed sufficient stent expansion. On follow-up, there was a significant resolution of right limb edema, and adjacent arterial pulsation/compression was deemed non-significant. CONCLUSION: The choice of venous stents is essential to prevent collapse from extrinsic compression, such as that from an adjacent artery. CLINICAL IMPACT: Carefully choosing venous stents is essential to ensure stent patency in the face of external compression.

Percutaneous Endovascular Management of a Splenic Vein Pseudoaneurysm Secondary to Pancreatic Pseudocyst.

CLINICAL IMPACT: This case report sheds light on a rare complication of pancreatitis, splenic vein pseudoaneurysm. The pseudoaneurysm was successfully treated percutaneously using a covered stent. The article also emphasizes the utilization and safety of transhepatic approach to interventions related to portal vein and its tributaries.

Iliac vein recanalisation and stenting accelerate healing of venous leg ulcers associated with severe venous outflow obstruction.

Obstruction involving the iliac veins and/or inferior vena cava is highly comorbid in patients with chronic venous leg ulcers and is a barrier to healing. Intervention with venous stenting is recommended to promote wound healing; however, there is limited data to quantify the effects of venous outflow restoration on wound healing. We retrospectively identified patients with venous ulcers and comorbid venous outflow obstruction. Data regarding demographics, wound size, degree of obstruction, interventions, wound healing and recurrence were collected. Intervention was performed when possible and patients were grouped based on whether or not the venous outflow was reopened successfully and maintained for at least 1 year. Outcomes, including time to wound healing, wound recurrence, stent patency and ulcer-free time, were measured. Patients who maintained a patent venous outflow tract experienced higher rates of wound healing (79.3%) compared to those with persistent outflow obstruction (22.6%) at 12 months (p < 0.001). Ulcer-free time for the first year was also greater with patent venous outflow (7.6 ± 4.4 months versus 1.8 ± 3.0 months, p < 0.0025). Patients with severe obstruction of the venous outflow tract experience poor healing of VLUs despite appropriate wound care. Healing time is improved and ulcer-free time increased after venous intervention with stenting to eliminate obstruction.

Predictive Factors of Stent Patency in Iliofemoral Venous Diseases in a Multicentre Cohort Study.

OBJECTIVE: This study assessed primary stent patency predictive factors in three groups of patients with history of lower limb (LL) vein thrombosis: non-thrombotic iliac vein lesion (NIVL), acute deep vein thrombosis (aDVT), and post-thrombotic syndrome (PTS). METHODS: Consecutive patients from January 2014 to December 2020 with history of LL vein stenting from seven hospitals were included. All patients received an iliac or common femoral venous stent and had at least a six month follow up available with stent imaging. Anticoagulant and antiplatelet therapy strategies employed after venous stenting are reported and compared between groups. RESULTS: This study included 377 patients: 134 NIVL, 55 aDVT, and 188 PTS. Primary patency was statistically significantly higher in the NIVL group (99.3%) compared with the PTS group (68.6%) (p < .001) and the aDVT group (83.6%) (p = .002). PTS patients received a statistically significantly greater number of stents (p < .001) and had more stents below the inguinal ligament (p < .001). Median follow up was 28.8 months (IQR 16, 47). Discontinuation of antiplatelet therapy at the last assessment was 83.6% for NIVL, 100% for aDVT, and 95.7% for the PTS group (p < .001). Discontinuation of anticoagulation therapy at the last assessment was 93.2% for NIVL, 25.0% for aDVT, and 70.3% for the PTS group (p < .001). The only predictor of worse primary patency in the aDVT group was long term anticoagulation before stenting. CONCLUSION: Patients with NIVL have better primary patency after venous stenting than patients with venous thrombotic disorders. Long term anticoagulation before stenting was the only factor associated with poorer primary patency in patients with aDVT.

Preprocedural imaging modalities in patients undergoing iliocaval venous recanalization and stent placement.

PURPOSE: To determine the diagnostic accuracy of preinterventional imaging modalities in patients being evaluated for iliocaval venous recanalization and stent placement. METHODS: Consecutive patients with iliocaval postthrombotic obstructions or nonthrombotic iliac vein lesions (NIVL), who were scheduled for recanalization, underwent duplex ultrasound (DUS), magnetic resonance venography (MRV), multiplanar venography (MPV), and intravascular ultrasound (IVUS). The diagnostic accuracies of DUS, MRV, and MPV were analyzed using IVUS as reference. RESULTS: A total of 216 limbs in 108 patients (80 patients with postthrombotic obstructions, 28 patients with NIVL) were examined. In patients with postthrombotic obstructions, the diagnostic sensitivities for the detection of lesions of the common femoral vein were 81% (95% CI 71-89%) for DUS, 76% (95% CI 65-85%) for MRV, and 86% (95% CI 76-93%) for MPV. The sensitivities for detecting lesions of the iliac veins were 96% (95% CI 89-99%) for DUS, 99% (95% CI 92-100%) for MRV, and 100% (95% CI 94-100%) for MPV. Regarding the inferior vena cava, the sensitivities were 44% (95% CI 24-65%) for DUS, 52% (95% CI 31-73%) for MRV, and 70% (95% CI 47-86%) for MPV. The sensitivities for detecting NIVL were 58% (95% CI 34-79%) for DUS, 90% (95% CI 68-97%) for MRV, and 95% (95% CI 73-99%) for MPV. CONCLUSION: In patients scheduled for recanalization of iliocaval postthrombotic obstructions, the sensitivities of DUS, MRV, and MPV were similar. In patients with suspected inferior vena cava involvement and in patients with NIVL, additional imaging with MR or conventional venography is required.

Extrinsic venous compression secondary to spine osteophytes.

OBJECTIVE: This study aims to report two cases of symptomatic extrinsic compression of the inferior vena cava and left iliac vein caused by vertebral osteophytes. METHODS: We present two case reports of extrinsic venous compression by vertebral osteophytes. Both cases were endovascularly treated, with a successful outcome. A review of the literature of this unusual condition is also presented. RESULTS: The first patient is an 80-year-old woman who presented to the vascular surgery clinic with bilateral lower extremity edema and pain. A computed-tomography angiography (CTA) revealed extrinsic compression of the inferior vena cava from enlarged osteophytes. Venography and intravascular ultrasound were performed, confirming the diagnosis. A self-expanding venous stent was successfully deployed in the inferior vena cava relieving the extrinsic compression. The edema resolved the following day and was discharged without complications. The second patient is a 61-year-old male that presented to the emergency department with a left iliofemoral deep venous thrombosis. CTA showed left iliac vein compression by a lumbar osteophyte. Percutaneous thrombectomy was successfully achieved and an expanding stent was deployed covering the entire lesion. One month after the procedure the patient died from COVID-19-associated respiratory failure. CONCLUSION: Osteophytes must be considered when dealing with extrinsic venous compression, especially in elderly people.

Closure of Post-thrombotic Iliac Arteriovenous Fistulas by Iliac Vein Recanalization.

PURPOSE: The purpose of this study was to report the closure of iliac arteriovenous fistulas associated with a post-thrombotic iliac vein occlusion by iliac venous stent recanalization. CASE REPORT: An 80-year-old woman presented with a worsening painful swelling of her left leg after an iliofemoral deep vein thrombosis 6 months ago. Duplex ultrasound and magnetic resonance venography revealed a post-thrombotic obstruction of her iliac veins as well as several arteriovenous fistulas between branches of her left external and internal iliac arteries and adjacent diseased venous segments. In a first attempt, coil embolization did not sustainably close these iliac arteriovenous fistulas. Direct stent recanalization of the chronically diseased iliofemoral venous segment, however, resulted in an immediate closure of arteriovenous shunt flow and subsequent improvement of clinical symptoms. Six months after iliac vein stent recanalization, still no fistulas could be detected any more, venous stents were fully patent, and the patient was free of symptoms. CONCLUSION: Post-thrombotic iliofemoral obstructions might be associated with the development of arteriovenous fistulas. Direct stent recanalization of the chronically occluded veins results in closure of related arteriovenous fistulas. CLINICAL IMPACT: This case suggests that the combined occurrence of post-thrombotic venous obstructions with arteriovenous fistulas, which are related to aforementioned venous lesions, should be evaluated for primary venous stent recanalization rather than fistula embolization.

Performance of Open and Closed Cell Laser Cut Nitinol Stents for the Treatment of Chronic Iliofemoral Venous Outflow Obstruction in Patients Treated at a Single Centre.

OBJECTIVE: A number of dedicated self expanding nitinol stents have been developed for use in the venous system, with both open cell (OC) and closed cell (CC) designs available. Data comparing these different designs are lacking. The objective of this study was to evaluate outcomes in patients treated with open and closed cells for unilateral chronic iliac vein obstruction. METHODS: A single centre retrospective cohort study was conducted, including all patients treated with a dedicated nitinol venous stent between 2014 and 2019. Stent patency and details of re-interventions (including lysis, venoplasty, reinforcement, extension, arteriovenous fistula formation) were examined in the first post-operative year. Subgroup analysis described outcomes for patients treated with OC and CC stents ending above the inguinal ligament and those who required extension into the common femoral vein. Cox regression analysis was used to identify factors associated with loss of primary patency. RESULTS: A total of 207 patients were included (OC 100 patients, CC 107 patients). There was no significant difference between the groups for age (OC 42 years, CC 44 years); gender (OC and CC 67% female); presence of post-thrombotic lesions (OC 71%, CC 73%); stenting across the inguinal ligament (OC 58%, CC 56%), or presence of inflow disease (OC 49%, CC 47%). Primary and cumulative patency at 12 months were similar between groups (primary: OC 63%, CC 65%; cumulative: OC 93%, CC 90%). Patients with a CC stent across the inguinal ligament had a greater risk of needing multiple re-interventions at one year compared with those with an OC stent (odds ratio 2.84, 95% confidence interval [CI] 1.16 - 6.9) but overall, the only factor significantly associated with loss of primary patency was inflow vessel disease (hazard ratio 3.39, 95% CI 1.73 - 6.62, p < .001). CONCLUSION: OC and CC dedicated nitinol venous stents were observed to perform similarly in terms of patency and symptom improvement at one year. Disease of the inflow vessels was the most important factor associated with a loss of stent patency irrespective of stent design.

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.

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.

Effect of Stent Strut Interval on Neointima Formation After Venous Stenting in an Ovine Model.

OBJECTIVE: The impact of stent design on venous patency is not well studied. The purpose of this study was to investigate the effect of stent material burden on endothelial coverage of stented venous segments, which may contribute to vessel healing and patency. METHODS: Segmented self expanding bare nitinol stents (18 × 50 mm) comprising 5 mm long attached metallic rings separated by 2, 5, or 8 mm gaps were implanted in the inferior vena cava (IVC) of 10 sheep. These stents were designed and manufactured for the purposes of this study. At six, 12, and 24 weeks after implantation the animals were euthanised and the stented vessels harvested for histomorphometric analysis. Three sections from the metallic part as well as the gaps between the struts were reviewed for quantification of endothelialisation after six, 12, and 24 weeks. The intimal thickness over and between the stent struts was measured. The endothelialisation score (graded from 1 for complete luminal endothelialisation to 5 for absence of endothelial cells) was determined. RESULTS: All stents were successfully deployed and all 10 sheep survived until the time of harvesting. Macroscopic inspection after 24 weeks showed only partial endothelialisation over stents with 2 mm and 5 mm skipped segments, whereas the stents with 8 mm skipped segments were totally incorporated into the vein wall. After 24 weeks, the mean (SD) neointimal thicknesses over stent struts with 2 mm, 5 mm, and 8 mm skipped segments were 254.0 (51.6), 182.2 (98.1), and 194.6 (101.1) µm, respectively. Comparison of endothelialisation scores of stents over time showed statistically significantly better endothelialisation over stents with 8 mm gaps after 12 and 24 weeks. CONCLUSION: Stent designs providing structural support to veins with larger gaps between the scaffold material appear to lead to faster and more complete endothelialisation as well as a thinner intimal layer.

Duplex Ultrasound Investigation for the Detection of Obstructed Iliocaval Venous Stents.

OBJECTIVE: Duplex ultrasound (DUS) is used for routine surveillance of stents in iliocaval veins, but direct visualisation is often challenging. Duplex ultrasound criteria for detecting venous stent obstruction (VSO) have not been defined to date. METHODS: A nested case control study of 120 patients (42 ± 17 years, 53% women, mean 2.7 ± 1.8 stents) was performed, and the performance of various duplex parameters for detecting VSO (defined as > 50% lumen diameter reduction or occlusion) was tested, confirmed by biplane venography or intravascular ultrasound (IVUS). Forty patients with VSO (25 with stent occlusion, 15 with >50% in stent stenosis) were matched to 80 control patients by age, gender and index diagnosis who fulfilled the following criteria: (1) ongoing symptom control (Villalta score < 5), (2) good image quality of entire stent segment, (3) spontaneous colour Doppler signal > 50% of lumen in entire stent segment, (4) at least two DUS where the baseline DUS was obtained within 24 h after successful venous intervention. RESULTS: The best test was the combination of peak flow velocity and flow pattern analysis at the stent inlet. A peak flow velocity >10 cm/s and a flow pattern spontaneously modulated by respiration ruled out VSO with a specificity of 93.7% (95% CI 86.0%-97.3%). A peak flow velocity ≤10 cm/s or any Doppler flow pattern other than spontaneously modulated by respiration was 92.1% (95% CI 79.2%-97.3%) sensitive to detect VSO. CONCLUSION: The combination of peak flow velocity and analysis of Doppler flow pattern at the stent inlet is accurate to diagnose or rule out stent occlusion. Indirect criteria should always be combined with direct visualisation of iliocaval stents since those may be less sensitive for detecting stent stenosis.

Histopathology of Iliocaval Venous In-Stent Restenosis Treated With Directional Atherectomy.

Purpose: To report the use of directional atherectomy to treat venous in-stent restenosis (ISR) and subsequent histopathological analysis of retrieved intrastent tissue. Case Report: A 55-year-old man presented with recurrent symptoms of venous congestion following iliofemoral stenting. The stents were found to be occluded on imaging. Directional atherectomy was used to recanalize the iliofemoral venous stents, which provided significant symptom relief. Tissue retrieved from within the stent demonstrated patterns of cellular components similar to arterial ISR. At 6-month follow-up, the stents remain patent, with no evidence of further ISR. Conclusion: Directional atherectomy is a potential treatment option for iliofemoral venous ISR. The pathological process of venous ISR demonstrates cellular changes similar to arterial ISR.

Mid-term Results of a Novel Dedicated Venous Stent for the Treatment of Chronic Thoracic Central Vein Obstruction of Benign Aetiology.

OBJECTIVES: Endovascular treatment is indicated for the treatment of symptomatic thoracic central vein obstruction (TCVO) but is limited by high rates of restenosis and the need for re-intervention. The aim was to assess the safety and mid-term patency of a novel dedicated venous stent for the treatment of TCVO of benign aetiology. METHODS: This was a prospective single centre observational study of 20 patients (median age 65 years, 50% male) referred for the treatment of symptomatic chronic (>three months duration) TCVO between May 2016 and January 2018. Balloon angioplasty with implantation of a self expanding nitinol stent (Vici, Boston Scientific, Marlborough, MA, USA) was performed in all patients. Clinical records including demographics, aetiologies and types of TCVO, and procedural details were recorded. Patients were followed up clinically at one, six, and 12 months. Primary and assisted primary patency were reported. RESULTS: All 20 lesions were total occlusions, of which 55% (n = 11) were de novo, 10% (n = 2) peri-stent restenosis, and 35% (n = 7) in-stent re-occlusion. The aetiology of TCVO was predominantly (95%) because of multiple or prolonged central venous line insertion. The procedural success rate was 90% (18/20) with no procedural complications. The median follow up was 13.5 months. Primary patency was 100% at 6 months. One patient required re-intervention for stent in segment restenosis at 7 months. The assisted primary patency rate was 100% at 12 months. CONCLUSION: Endovascular treatment of benign TCVO with the novel dedicated venous stent was safe and effective in relieving obstructive symptoms with excellent one year patency rates.

Early Venous Stent Failure Predicted by Platelet Count and Neutrophil/Lymphocyte Ratio.

BACKGROUND: Inflammation and platelet activation have been shown to be involved in acute thromobogenicity following venous occlusive conditions. The aim of this study was to identify the association of baseline platelet count and neutrophil/lymphocyte ratio (NLR) with venous stent failure. Methods and Results: Patients who underwent technically successful iliocaval venous stent placement with available baseline complete blood count and follow-up stent patency data were selected (n=50). Stent failure was defined as >50% stenosis or occlusion at follow-up angiography, contrast-enhanced CT, MRI or duplex US. Median patient age was 49.5 years (range, 13-76 years), and 62% were female. Median follow-up time was 10.2 months (range, 0.1-76.4 months). Stent failure occurred in 13 patients (26%) after a median of 1.2 months (range, 1 day-76.4 months). On multivariable-adjusted Cox modeling, baseline platelets (HR, 2.28; P=0.004) and WBC count (HR, 2.03; P=0.013) were significantly associated with stent failure on follow-up; neutrophils (HR, 16.10; P=0.050); and NLR (HR, 12.19; P=0.050) had borderline significance. Compared with patients without stent failure, those with early, but not late, stent failure had higher baseline platelets (P=0.031) and neutrophils (P=0.025), and NLR (P=0.026). CONCLUSIONS: Baseline platelet count and NLR are associated with early but not late failure of iliocaval venous stents. This suggests different pathophysiologic mechanisms and a role for both platelet activation and inflammatory mechanisms in early rather than late stent thrombosis. Future research is needed to better explain this novel finding.