An overview of in-stent restenosis in iliofemoral venous stents

Interventional treatment for post-thrombotic chronic venous obstruction: Progress and challenges

Chronic venous obstruction, including nonthrombotic iliac vein lesions and post-thrombotic syndrome, presents a significant burden on patients' quality of life and health care systems. Venous recanalization and stenting have emerged as promising minimally invasive approaches, yet challenges in patient selection, procedural techniques, and long-term outcomes persist. This review synthesizes current knowledge on the interventional treatment of post-thrombotic syndrome, focusing on the evolution of endovascular techniques and stenting. Patient selection criteria, procedural details, and the characteristics of dedicated venous stents are discussed. Particular emphasis is given to the role of inflow and other anatomical considerations, along with postoperative management protocols for an optimal long-term outcome.

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.

RevCore thrombectomy system for treatment of chronic left external and common iliac vein stent occlusion

In recent years, deep venous stenting has increasingly become a treatment strategy for post-thrombotic syndrome. Stent thrombosis can occur, resulting in symptom recurrence despite medical therapy, and there are few options available for durable stent patency restoration. We present a case of a 50-year-old male with prior iliocaval reconstruction that experienced recurrent left lower extremity swelling secondary to occlusion of left external iliac and common iliac vein stents during follow-up. Mechanical thrombectomy with the RevCore System and angioplasty was performed. One month later, the patient demonstrated widely patent bilateral iliac vein stents and complete symptomatic resolution. The RevCore System is a feasible alternative for treatment of chronic in-stent thrombosis.

Endovascular mechanical thrombectomy of iliofemoral venous stent occlusion with the novel RevCore thrombectomy system: case reports and literature review

Venous in-stent restenosis is not completely understood, and the currently available treatment is usually unsatisfactory. We describe the cases of two patients treated with the RevCore thrombectomy system (Inari Medical), designed for venous in-stent thrombosis. Case 1 involves a 62-year-old woman with post-thrombotic syndrome from iliac vein stent placement 15 years earlier. Case 2 describes a 30-year-old woman with post-thrombotic syndrome from recurrent iliac vein stent occlusion, despite therapeutic anticoagulation. Both patients had previous recanalization attempts at outside facilities that were unsuccessful. The RevCore system was safe and feasible in these initial cases, and more studies are warranted.

Lower extremity woven and nonwoven venous stent morphology and luminal changes

OBJECTIVE

Venous stents are a common treatment modality for obstructive venous disease. Venous stents differentiate themselves by either a woven or braided structure, open or closed cell arrangement or based on material composition (elgiloy vs nitinol). Changes in the morphology of venous stents over time may contribute to restenosis or thrombosis. Woven elgiloy stents are prone to proximal and distal edge deformation compared with dedicated venous stents, which offer increased radial force at stent edges. The objective of this study is to describe luminal morphological changes among various venous stents and between woven to nonwoven venous stent configuration, over time.

METHODS

A retrospective review at a single institution between January 2014 and June 2021 identified patients treated with venous stents. Patients with iliac and/or femoral venous stents with intraoperative intravascular ultrasound and a postoperative computed tomography scan were included in the study. Cross-sectional diameters measurements were taken at proximal, middle, and distal portions of each stent from intravascular ultrasound examination at the time of initial stenting and compared with the cross-sectional diameter measurements taken from computed tomography imaging at follow-up. A paired t test was used to compare the luminal change with a D'Agostino-Pearson test used for normality.

RESULTS

Fifty-four stents distributed among 38 patients were identified. The mean time to follow-up was 17.5 months. Stents were placed in the common iliac vein (n = 37, 68.5%), external iliac vein (n = 14, 25.9%), and common femoral vein (n = 3, 5.6%). Implanted stents included the Boston Scientific Wallstent (n = 23, 42.6%), Bard Venovo (n = 3, 5.6%), Boston Scientific Vici (n = 23, 42.6%), and Medtronic Abre (n = 5, 9.3%). The mean luminal loss was measured at 2.12 mm proximally (95% confidence interval [CI], 1.64-2.60; P<.001), 1.29 mm at the mid-stent (95% CI, 0.83-1.74, P<.001), and 1.56 mm distally (95% CI, 0.99-2.12; P<.001). There was no significant difference in luminal changes between woven and nonwoven stents at proximal (P = .374), middle (P = .179), and distal (P = .609) stent measurements.

CONCLUSIONS

This study reports morphological changes within venous stents and between woven and nonwoven venous stents. Our findings demonstrate that the edge-stent luminal decrease traditionally attributed to woven configurations also occurs with the newer nonwoven stents. Additional factors such as anatomical location, pelvic curvature, and other external forces may be accountable for this change rather than geometrical configuration of the stent.

Endovascular treatment of chronic ilio-femoral vein obstruction with extension below the inguinal ligament in patients with post-thrombotic syndrome

OBJECTIVE

This study aimed to evaluate postoperative outcomes of patients with chronic iliofemoral venous outflow obstruction and post-thrombotic syndrome (PTS) who underwent endovascular recanalization and stenting across the inguinal ligament.

METHODS

All consecutive patients with chronic iliofemoral venous outflow obstruction and PTS were included in the analysis, from January 2018 and February 2022. Preoperative, intraoperative, and postoperative outcomes were assessed. Primary endpoints analyzed were major adverse events (MAEs) at 30 days and primary patency rate at 2 years of follow-up. Secondary endpoints assessed were secondary patency rate, target vessel revascularization, and clinical improvement evaluated with the Venous Clinical Severity Score (VCSS) classification, Villalta scale, and visual analog scale (VAS), respectively.

RESULTS

A total of 63 patients (mean age, 48.1 ± 15.5 years; female, 61.9%) were evaluated. No intraoperative and 30-day postoperative complications were documented. The technical success rate was achieved at 100%. Overall, one in-stent occlusion and five in-stent restenosis were detected during follow-up. The primary patency rate was 93.7% (95% confidence interval [CI], 87.8%-99.9%) and 92.1% (95% CI, 85.6%-99%), at 1- and 2-year follow-up, respectively (Kaplan-Meier analysis). Target vessel revascularization was conducted in two cases, resulting in a secondary patency of 98.4% (95% CI, 95.4%-100%) at 2 years of follow-up. Stent fracture and/or migration were not observed during follow-up. A significant clinical improvement in the patient's quality of life was documented. The median improvement of VCSS and Villalta scores were 4 (interquartile range, 2-7; P = .001), and 3 (interquartile range, 1.5-5; P = .001) vs baseline at the last follow-up. Overall, pain reduction of 17 mm on the VAS scale was documented at 2 years of follow-up. At multivariate analysis, presence of trabeculation into the femoral vein and deep femoral vein (odds ratio, 1.89; 95% CI, 0.15-6.11; P = .043), and Villalta scale >15 points at admission (odds ratio, 1.89; 95% CI, 0.15-6.11; P = .043) were predictive for in-stent occlusion during the follow-up.

CONCLUSIONS

The use of a dedicated venous stent across the inguinal ligament was safe and effective for the treatment of symptomatic iliofemoral venous disease with acceptable primary and secondary patency rates at 2 years of follow-up.

An Evaluation of the Duration of Oral Anticoagulant Use Among Patients Undergoing Endovascular Treatment of Nonthrombotic Iliac Vein Lesions

BACKGROUND

This study aimed to compare clinical outcomes associated with the duration of postoperative direct oral anticoagulant (DOACs) therapy in patients with nonthrombotic iliac vein lesions.

METHODS

We retrospectively analyzed 176 consecutive patients who underwent stenting for nonthrombotic iliac vein lesions between March 2018 and December 2021. In total, 99 and 77 patients were discharged on a 3-month and >3-month regimen of DOAC therapy, respectively. The primary cumulative endpoint was a composite of thrombotic complications, bleeding complications, primary patency, primary-assisted patency, and secondary patency within 1 year.

RESULTS

Patients undergoing 3-month and >3-month DOAC therapy were similar in age, sex, lesion site, symptoms, and average stent diameter and length. Upon multivariate analysis, the primary cumulative endpoint did not differ between the 2 groups (hazard ratio [HR]: 1.18; 95% confidence interval [CI]: 0.42-3.30; P = 0.76). Moreover, the primary patency at 1 year did not differ between the groups (HR: 1.50; 95% CI: 0.14-16.54; P = 0.74). Furthermore, there were no discernible differences in the secondary endpoints of bleeding complications (HR: 0.66; 95% CI: 0.22-1.96; P = 0.45) or thrombotic complications (HR: 1.79; 95% CI: 0.55-5.80; P = 0.34) between the groups.

CONCLUSIONS

The 3-month regimen of DOAC therapy showed a similar risk of postoperative thrombosis and bleeding when compared to longer DOAC therapy durations over the course of 1 year following endovascular intervention. This could be a preferred option for patients with a higher estimated bleeding risk after venous stenting.

Novel venous balloon for compliance measurement and stent sizing in a post-thrombotic swine model

Objective: Real-time accurate venous lesion characterization is needed during endovenous interventions for stent deployment. The goal of this study is to validate a novel device for venoplasty sizing and compliance measurements. Methods: A compliance measuring sizing balloon (CMSB) uses real-time electrical conductance measurements based on Ohm's Law to measure the venous size and compliance in conjunction with pressure measurement. The sizing accuracy and repeatability of the CMSB system were performed with phantoms on the bench and in a swine model with an induced post thrombotic (PT) stenosis in the common femoral vein of swine. Results: The accuracy and repeatability of the CMSB system were validated with phantom bench studies of known dimensions in the range of venous diameters. In 9 swine (6 experimental and 3 control animals), the luminal cross-sectional areas (CSA) increased heterogeneously along the PT stenosis when the CMSB system was inflated by stepwise pressures. The PT stenosis showed lower compliance compared to the non-PT vein segments (5 mm2 vs. 10 mm2 and 13 mm2 at a pressure change of 40 cm H2O). Compliance had no statistical difference between venous hypertension (VHT) and Control. Compliance at PT stenosis, however, was significantly smaller than that at Control and VHT (p < 0.05, ANOVA). Conclusion: The CMSB system provides accurate, repeatable, real-time measurements of CSA and compliance for assessment of venous lesions to guide interventions. These findings provide the impetus for future first-in-human studies.

An Overview of Specific Considerations in Chronic Venous Disease and Iliofemoral Venous Stenting

Unlike arterial disease, chronic venous disease (CVD) is rarely life-threatening or limb-threatening. However, it can impose substantial morbidity on patients by influencing their lifestyle and quality of life (QoL). The aim of this nonsystematic narrative review is to provide an overview of the most recent information on the management of CVD and specifically, iliofemoral venous stenting in the context of personalized considerations for specific patient populations. The philosophy of treating CVD and phases of endovenous iliac stenting are also described in this review. Additionally, the use of intravascular ultrasound is described as the preferred operative diagnostic procedural tool for iliofemoral venous stent placement.

Iliac vein stent failure in community practice and results of corrective reinterventions

OBJECTIVE

The goal of endovenous stenting is to relieve venous obstruction and reduce peripheral venous hypertension by using large caliber venous stents in the presence of adequate venous inflow and outflow for the stented conduit. The aim of this report is to describe the technical reasons and outcomes for reinterventions in a subset of patients who had a history of iliac vein stenting and were now referred to us at a specialty venous clinic for further care.

METHODS

From January 2016 to December 2021, records of all patients who were referred to us with a history of iliac vein stenting performed at an outside facility and who had a reoperation performed at our center were retrospectively analyzed.

RESULTS

A total of 149 limbs underwent a deep venous reintervention after a failure of a trial of conservative therapy. The mean age of the sample was 57 ± 16 years. The ratio of non-thrombotic iliac vein lesions to post-thrombotic lesions was 1:2.5. The majority of the patients (84%) were CEAP class C4 or higher. The most common reason for reintervention was stent occlusion (74%), followed by iatrogenic stenosis (53%) and in-stent restenosis/shelving (38%). There was a trend for improvement in all clinical parameters (venous clinical severity score, visual analog scale for pain, and edema grade) after the reintervention. Poor inflow was present in 70% of limbs with stent occlusion. The median diameters of stented common femoral vein, external iliac vein, and common iliac vein prior to reintervention were 12, 12, and 13 mm, respectively. The median diameters of stented common femoral vein, external iliac vein, and common iliac vein after reintervention were 14, 15, and 16 mm, respectively. Eighty-eight percent of limbs required at least one further reintervention after initial reoperation.

CONCLUSIONS

Venous reoperations are generally infrequent and required in a small number of patients. Poor inflow appeared to be a common cause of stent occlusion. Iatrogenic stenosis is another common reason for venous reoperation and is difficult to fully rectify through current endovascular techniques and tools. Use of intravascular ultrasound planimetry routinely in every deep venous intervention and thorough knowledge of the principles of venous stenting outlined in this report may help forestall the need for reoperative deep venous surgery in some cases.

Angioscopic evaluation after venous stents

BACKGROUND

Venous stenting is increasingly used to manage femoro-ilio-caval venous outflow obstruction/stenosis due to post-thrombotic syndrome. Although the safety, efficacy, and long-term patency of venous stents have been reported, re-interventions due to stent occlusion and in-stent restenosis (ISR) have also been reported. The mechanism of ISR and the in-stent neointimal growth after venous stenting remains unclear. We performed angioscopy to evaluate intraluminal details after venous stenting, allowing real-time direct visualization of the vessel lumen.

METHODS

Ten angioscopic procedures in four patients with post-thrombotic syndrome were performed. All evaluated vessels were stented iliac veins, and their native pathology was chronic post-thrombotic occlusion. Nine procedures in three patients underwent serial evaluation of the neointimal changes after stent implantation to study the natural time course of neointimal proliferation/coverage over the stent. The serial follow-up angioscopic evaluations were performed at the end of the venous stent deployment procedure, and at 6 months, 12 months, and 24 months. One procedure was performed 1 month after the stent implantation to evaluate ISR, which was observed at the first month of routine stent surveillance. A 5.7F angioscope was used to visualize the target veins. Continuous irrigation was used to displace blood and clear the visual field.

RESULTS

At 6 months after stent implantation, stent struts were covered by a thin neointima in two of the three patients. The struts were partially covered in one patient, but there was little neointimal growth overall. Neointimal coverage increased over time, and at 12 months stent struts in 2 patients were almost completely covered. There was no significant change between the 12 and 24 months after stent implantation. In the ISR case, angioscopy demonstrated an overgrown thickened neointima, and the stent struts were fully embedded and invisible in the entire stented area. No thrombus and no webs or trabeculae were found in the area evaluated as an ISR lesion.

CONCLUSIONS

At 6 months after stent placement, the stent struts were almost covered by a neointima. The stent struts were completely covered 1 year after stent implantation. Neointimal coverage was unchanged from the 1-year follow-up to the 2-year follow-up, suggesting that neointimal proliferation proceeded gradually with subsequent neointimal remodeling up to 1 year. The cause of ISR might be the overgrown thickened neointima rather than the formation of thrombosis.

Management of May Thurner Syndrome in Pregnant Patients

May Thurner Syndrome contributes to thromboembolic disease and can cause significant morbidity in pregnant patients secondary to exaggerated anatomic relationships and physiologic changes in the hematologic system favoring thrombogenesis. Because this condition is both underrecognized and underreported, management in pregnant and postpartum patients is based on expert opinion without any formal evidence-based guidance. Herein, we review five pregnancies in four patients with May Thurner Syndrome and general management strategies. Through collaborative and multidisciplinary care, patients with May Thurner Syndrome can be safely and successfully managed during pregnancy and the postpartum period with appropriate anticoagulation.

Options in the treatment of superficial and deep venous disease in patients with Klippel-Trenaunay syndrome

OBJECTIVE

Klippel-Trenaunay syndrome (KTS) is a congenital mixed mesenchymal malformation syndrome that includes varicose veins, capillary and venous malformations, lymphatic abnormalities, and hypertrophy of various connective tissue elements. The purpose of the present study was to describe the clinical characteristics and outcomes in a subset of patients with KTS in whom venous interventions, including iliofemoral venous stenting, were performed after failure of conservative therapy.

METHODS

A single-center retrospective data review of 34 patients with KTS who had undergone interventions for venous disease between January 2000 and December 2020 was performed.

RESULTS

Their mean age was 38.4 ± 17.5 years (range, 12-80 years). No gender predilection was found. Of the 34 patients, 61% had had all three features of the classic triad for KTS. Varicose veins were present in all 34 patients (100%), and 30% had had a history of bleeding varicosities. Most patients (79%) had CEAP (Clinical, Etiology, Anatomy, and Pathophysiology) class ≥C4. Of the 34 patients, 30% had a history of deep vein thrombosis and/or pulmonary embolism. Factor VIII elevation was the most common thrombophilia condition (12%). The venous filling index was elevated at baseline (5.9 ± 5.1 mL/s) and did not normalize despite intervention (3.5 ± 2.3 mL/s; P = .04). The superficial venous interventions (n = 35) included endovenous laser therapy; stripping of the great saphenous vein, small saphenous vein, anterior thigh vein, or marginal vein; ultrasound-guided sclerotherapy; and stab avulsion of varicose veins. One coil embolization of a perforator vein was performed. Deep interventions (n = 19) included endovenous stenting (n = 15), popliteal vein release (n = 3), and valvuloplasty (n = 1). The venous clinical severity score had improved from 9.4 ± 4.5 to 6.2 ± 5.6 (P = .04). The visual analog scale for pain score had improved from 5.5 ± 2.7 to 2.5 ± 3.3 (P = .008). Healing of ulceration was noted in 75% of the patients. Significant improvements in the total pain (P = .04) and total psychological (P = .03) domains were noted in the 20-item chronic venous disease quality of life questionnaire.

CONCLUSIONS

Superficial and deep venous interventions are safe and effective in patients with KTS when conservative therapy has failed. Iliofemoral venous stenting is a newer option that should be considered in the treatment of chronic deep venous obstructive disease in patients with KTS in the appropriate clinical context. An aggressive perioperative deep vein thrombosis prophylaxis protocol should be in place to reduce thromboembolic complications in these patients.

Percutaneous laser recanalization in chronically occluded iliofemoral venous stents

Occlusion is a challenging complication of endovenous stenting. The treatment of chronic iliofemoral stent occlusion involves wire recanalization followed by balloon angioplasty. However, this approach will not always be successful. To treat such cases, we have successfully used a laser recanalization technique in 34 limbs (31 patients). This technique involved the use of a laser to first create a channel through the chronically occluded stent, followed by balloon angioplasty to improve the caliber of this recanalized tract. The mean age of the patients was 52 ± 13.6 years (range, 24-73 years). No adverse events related to the use of the laser occurred. Following laser recanalization, the venous clinical severity score had improved from 8.2 ± 4 to 5.1 ± 3.3 (P < .0001). The visual analog scale score for pain had improved from 7.8 ± 2.5 to 4.9 ± 3 (P = .0009). The grade of swelling had improved from 2.7 ± 1.3 to 1.6 ± 1.4 (P = .0001). At 12 months after intervention, the primary stent patency was 60% (standard error of the mean, 9.3%), and the secondary stent patency was 80%. Excimer laser recanalization of chronically occluded venous stents appears to be a rarely required but useful modality with reasonable clinical outcomes. Further reinterventions might be required to maintain long-term stent patency.

Hybrid surgery techniques for the treatment of in-stent restenosis after 5 years of femoral artery self-expanding bare-metal stent implantation: A case report

RATIONALE

Lower extremity arteriosclerosis obliterans (ASO) disease is caused by the formation of atherosclerotic plaque in the femoral artery, which causes the stenosis and occlusion of lower legs, and then leads to chronic limb ischemia. Stent intervention is the most common treatment for ASO in the lower extremities, although there is a risk of overstretching or fracturing the stent, resulting in stent rupture. We provide a unique method for treating stent rupture.

PATIENT CONCERNS

A 79-year-old male presented with intermittent claudication of the left lower limb for 6 months. Five years ago, a stent was placed in the lower extremity femoral artery. According to the examination, the stent suffered a modest torsional fracture.

DIAGNOSIS

The case was diagnosed with lower extremity ASO.

INTERVENTIONS

We performed a combination of femoral endarterectomy and interventional surgery.

OUTCOMES

Blood flow was restored after the hybrid operation has been used to treat arterial stenosis in the lower limbs.

CONCLUSION

Integrating vascular interventional surgeries can shorten surgical procedures time and increase success rates.

Diabetes and restenosis

Restenosis, defined as the re-narrowing of an arterial lumen after revascularization, represents an increasingly important issue in clinical practice. Indeed, as the number of stent placements has risen to an estimate that exceeds 3 million annually worldwide, revascularization procedures have become much more common. Several investigators have demonstrated that vessels in patients with diabetes mellitus have an increased risk restenosis. Here we present a systematic overview of the effects of diabetes on in-stent restenosis. Current classification and updated epidemiology of restenosis are discussed, alongside the main mechanisms underlying the pathophysiology of this event. Then, we summarize the clinical presentation of restenosis, emphasizing the importance of glycemic control in diabetic patients. Indeed, in diabetic patients who underwent revascularization procedures a proper glycemic control remains imperative.