Pathologic characteristics of human venous in-stent stenosis and stent occlusion

The impact of stent protrusion into the inferior vena cava or jailing of the contralateral iliac vein on the incidence of contralateral deep vein thrombosis following venous stenting

OBJECTIVE

Iliac vein stenting is the standard of care for patients with pelvic venous disorders secondary to symptomatic iliac vein outflow obstruction. Venous stents are often extended proximally into the inferior vena cava (IVC) which may result in partial or complete coverage of the contralateral iliac vein. The purpose of this investigation is to determine if extension of iliac vein stents into the IVC results in increased risk of contralateral deep venous thrombosis (DVT).

METHODS

We retrospectively reviewed prospectively collected data from 409 patients who underwent iliac vein stenting at the Center for Vascular Medicine (CVM) from 2019 to 2020. Stent type, covered territories, initial and follow-up consults, ultrasound and operative reports were reviewed to assess for incidence of post-implantation DVT. Patients were stratified into three groups: Iliac vein stents which protruded into the IVC, stents that completely covered the orifice of the contralateral iliac vein and those with no stent protrusion into the IVC.

RESULTS

Out of 409 patients, the average age was 53.96 ± 13.40 years with 94 males and 315 females. All stents placed were Venovo stents and all iliac vein lesions were non-thrombotic stenoses. The average follow-up period was 14.35 ± 10.09 months. The most common territories stented were the IVC-LCIV-LEIV (n = , 74%) and the IVC-RCIV-REIV (n = , 26%). Stent protrusion and distance into the IVC in millimeters (mm) was the following: Partial protrusion (n = 314, 77%, 27.6 ± 19.1), jailing of the contralateral iliac vein (n = 78, 19%, 45.9 ± 18.6), no protrusion (n = 16, 4%). The overall DVT rate post-implantation was 0.49% (n = 2). No DVTs ipsilateral to the index stent were identified and both DVTs were contralateral DVTs. A hypercoaguable disorder was reported in 6 patients (1.5%). There were no significant differences in prevalence of contralateral DVT between the three groups. (p = .35).

CONCLUSION

The rate of contralateral DVTs post iliac vein stenting with Nitonol based stents is extremely low. Partial or complete coverage of the contralateral iliac vein via stenting does not result in an increased incidence of contralateral DVT in the short-term. Longer follow up is needed to determine if contralateral DVTs occur after long-term implantation.

Effect of stent shape in areas of high compression on patency rates after venous recanalization in patients with chronic venous obstruction

BACKGROUND

Venous stenting of the obstructed iliofemoral veins has gained significant popularity over recent years due to its efficacy in restoring venous flow and alleviating symptoms associated with chronic venous obstruction (CVO). The success of venous stenting has been demonstrated through high patency rates, even in cases where stents are implanted in areas of high compression. These stents have been observed to adopt an elliptical shape at areas of high compression, deviating from the expected circular morphology that stents are designed to maintain. This phenomenon raises important questions about its potential impact on stent function and long-term patency rates. The objective of this study was to investigate, through a retrospective analysis, the presence and clinical impact of non-circular-shaped venous stents on patency rates.

METHODS

From December 2015 to December 2020, a cohort of 115 patients (127 limbs) diagnosed with chronic obstruction of the iliofemoral veins underwent venous angioplasty with stent implantation. Throughout follow-up visits, detailed data were collected, including patient demographics, characteristics, stent types, and ultrasound findings, while especially focusing on the shape and diameter of stents at areas of known external compression, such as the May-Thurner point and under the inguinal ligament.

RESULTS

The average follow-up duration was 21.9±8.7 months. The primary patency rate was 79.5%, with an assisted primary patency rate of 92.1% and a secondary patency rate of 96.7%. All the stents implanted were dedicated venous stents, which demonstrated favorable outcomes overall. However, during the follow-up period, 76.56% of the stents were found to have adopted an elliptical shape at areas of high external compression, regardless of the type or structure of the stent. Interestingly, neither the change in stent shape nor a reduction in stent area of less than 25% showed any statistically significant impact on the overall patency rates.

CONCLUSIONS

This study demonstrates that changes in stent shape are to be expected at points of high external pressure. However, as long as these changes do not lead to a severe reduction in stent lumen (<25% of stent area), they do not negatively impact patency rates.

The Long-Term Prognosis of Endovascular Thrombectomy in Patients with Acute Left Iliofemoral Vein Thrombosis Combined with Left Iliac Vein Compression

BACKGROUND

This study investigated the long-term outcomes of different thrombus removal methods in patients with acute left iliofemoral vein thrombosis (IFDVT) accompanied by left iliac vein compression (LIVC).

METHODS

This was a single-center cohort study. 240 patients with acute left-sided IFDVT complicated by LIVC were categorized based on their treatment approach into 2 groups: those receiving anticoagulation alone with no pharmacomechanical catheter-directed thrombolysis applied (No-PCDT group) and those undergoing anticoagulation combined with pharmacomechanical catheter-directed thrombolysis (PCDT group). The PCDT group was further divided into 3 subgroups: anticoagulation combined with percutaneous mechanical thrombectomy (PMT group), anticoagulation combined with catheter-directed thrombolysis (CDT group), and anticoagulation combined with both PMT and catheter-directed thrombolysis (PMT + CDT group). The incidence of postthrombotic syndrome (PTS) was assessed using Villalta scores and Venous Clinical Severity Scores (VCSS). Patients were followed up for 24 months to compare long-term outcomes.

RESULTS

The No-PCDT group consisted of 123 individuals, while the PCDT group comprised 117, with 36 in the CDT subgroup, 41 in the PMT subgroup, and 40 in the PMT + CDT subgroup. The follow-up period ranged from 3 to 24 months. The PCDT group was associated with a reduced incidence of PTS and a lower risk of high VCSS (Villalta scale ≥5 or presence of ulcer: 22% PCDT vs. 39% No-PCDT; odds ratio [OR], 0.446; 95% confidence interval [CI], 0.253-0.787; P = 0.005; and VCSS ≥ 4: 22% PCDT vs. 34% No-PCDT; OR, 0.551; 95% CI, 0.311-0.978; P = 0.042). Among the 3 subgroups of PCDT cohort, compared to the CDT group, the PMT group showed a decreased incidence of PTS and a lower risk of high VCSS (Villalta scale ≥ 5 or ulcer: 12% PMT vs. 39% CDT; OR, 0.218; 95% CI, 0.069-0.690; P = 0.010; and VCSS ≥ 4: 12% PMT vs. 36% CDT; OR, 0.246; 95% CI, 0.077-0.781; P = 0.017). The PMT + CDT group also demonstrated a reduced incidence of PTS (18% PMT + CDT vs. 39% CDT; OR, 0.333; 95% CI, 0.116-0.958; P = 0.041) compared to the CDT group, but did not show a significant reduction in the risk of high VCSS (20% PMT + CDT vs. 36% CDT; P = 0.121). Compared to the PMT group, the PMT + CDT group did not significantly reduce the incidence of PTS (12% PMT vs. 18% PMT + CDT; P = 0.504) or the rate of high VCSS (12% PMT vs. 20% PMT + CDT; P = 0.343).

CONCLUSIONS

In patients with acute left IFDVT complicated by LIVC, PMT may serve as a more efficacious method for thrombus removal compared to CDT and combined PMT + CDT in reducing both the incidence of PTS and the risk of high VCSS.

Efficacy and safety of a dedicated venous stent for the treatment of iliofemoral venous obstruction: A single center experience

BACKGROUND

Endovascular recanalization with venous stenting is the preferred treatment for iliofemoral venous obstruction. We reviewed our institutional experience and mid-term outcomes with endovascular therapy for iliofemoral venous obstruction using the VenovoTM Self-expanding Venous Stent (BARD Peripheral Vascular, Inc., Tempe, AZ, USA).

METHODS

Between October 2022 and March 2024, patients with iliofemoral venous obstruction treated with VenovoTM Self-expanding Venous Stents were retrospectively analyzed. Patients were monitored at 3, 6, and 12 months. The primary endpoint was 12-month primary patency, defined as computed tomography venography-derived stenosis <50% and no target venous revascularization. Secondary endpoints included stent intimal hyperplasia and pain venous clinical severity scores (VCSSs).

RESULTS

We evaluated 51 limbs from 40 patients (mean age: 61.7 ± 10.7 years; 26 females), including three acute deep venous thrombosis (DVT)cases, six post-thrombotic syndrome (PTS) cases, and 42 non-thrombotic iliofemoral vein lesion cases. All (100%) underwent successful endovascular treatment, with five undergoing combined stent deployment. The interventional operation-related complication rate was 1/51 (1.96%). The median follow-up was 14.6 months (range: 12-18 months). The primary patency rate at 1 year was 90%. Freedom from stent intimal hyperplasia at 12 months was 74.51% (38/51), and 3.92% (2/51) had in-stent stenosis >50%, which was reduced after high-pressure balloon dilation at 6 months. The mean VCSS decreased from a baseline of 13.1.7 ± 3.7 to 3.3 ± 1.6 at 12 months (p < .0001). No complications were noted during follow-up.

CONCLUSIONS

Stenting iliofemoral venous obstruction using the VenovoTM Self-expanding Venous Stent appears to be safe and effective, with a high rate of 1-year clinical patency and a low reintervention rate.

The Safety and Efficacy of ZelanteDVT™ Catheter Rheolytic Thrombectomy in the Treatment of Patients with Iliac Vein Stent Thrombosis

BACKGROUND

To examine the safety and efficacy of ZelanteDVT™ catheter rheolytic thrombectomy in the treatment of patients with iliac vein stent thrombosis.

METHODS

A retrospective analysis method was conducted by means of collecting the data of 32 patients who had completed the treatment of iliac vein stent thrombosis with ZelanteDVT catheter rheolytic thrombectomy from March 2019 to March 2023. Data on clinical characteristics, technical success, clinical success, complications, and early follow-up were analyzed.

RESULTS

The technical success rates were 100%, intraoperatively, in which 22 cases were improved to thrombus clearance Grade II (50-90%), 10 were Grade III (>90%). There were 21 cases treated with subsequent catheter-directed thrombolysis, and the average urokinase administration of (120.90 ± 29.63)∗10ˆ4 units. The clinical success rates were 100% and the swelling of the affected limbs were significantly improved, a significant difference in the pre/postoperative between-thigh circumference difference [(5.16 ± 1.08) vs. (1.75 ± 0.84), P < 0.000]. The pre/postoperative Venous Clinical Severity Score was [(12.94 ± 1.70) vs. (7.44 ± 1.31), P < 0.000]. No serious complications occurred during the perioperative period. The postoperative and 12-month stent patency rate was 100.00% (32/32) and 71.88% (23/32), respectively.

CONCLUSIONS

The ZelanteDVT catheter rheolytic thrombectomy seems to have a promising application prospect for the treatment of patients with iliac vein stent thrombosis.

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.

Histological Features of In-Stent Restenosis after Iliac Vein Thrombus Removal and Stent Placement in a Goat Model

PURPOSE

To establish an animal model for in-stent restenosis (ISR) after postthrombotic iliac vein stent placement and characterize histopathological changes in tissue within the stented vein.

MATERIALS AND METHODS

Iliac vein thrombosis was induced using balloon occlusion and thrombin injection in 8 male Boer goats. Mechanical thrombectomy and iliac vein stent placement were performed 3 days after thrombosis induction. Restenosis was evaluated by venography and optical coherence tomography (OCT) at 1 and 8 weeks after stent placement, and stent specimens were taken for pathological examination after the animals were euthanized.

RESULTS

Thrombosis induction was successful in all 8 goats, with >80% iliac vein occlusion. After thrombus removal, OCT revealed considerable venous intimal thickening and a small number of mural thrombi. Neointimal hyperplasia with thrombus formation was observed in all goats 1 week after stent implantation; the degree of ISR was 15%-33%. At 8 weeks, the degree of ISR was 21%-32% in 3 goats, and stent occlusion was observed in 1 goat. At 1 week, the neointima predominantly consisted of fresh thrombi. At 8 weeks, proliferplastic fibrotic tissue and smooth muscle cells (SMCs) were predominant, and the stent surfaces were endothelialized in 2 of 3 goats and partially endothelialized in 1 goat.

CONCLUSIONS

In the goat model, postthrombotic neointimal hyperplasia in the venous stent may result from time-dependent thrombus formation and organization, accompanied by migration and proliferation of SMCs, causing ISR. These results provide a basis to further explore the mechanism of venous ISR and promote the development of venous stents that reduce neointimal hyperplasia.

Mechanical thrombectomy of venous in-stent thrombosis with the novel RevCore thrombectomy system: A report of 2 cases

In-stent thrombosis (IST) is a common venous stent complication. Acute IST warranting intervention can generally be treated with catheter-directed thrombolysis or aspiration thrombectomy. However, thrombosed stents often have chronic-appearing components that pose a significant treatment challenge as the thrombus firmly adheres to the stent and vessel wall and becomes resistant to thrombolytics and aspiration thrombectomy. Alternate treatment options such as venoplasty, stent relining, and medical management do not remove existing IST but rather remodel the lumen with limited long-term efficacy. This report details 2 cases of chronic-appearing IST successfully debulked with the novel RevCore Thrombectomy System. RevCore, designed to mechanically liberate acute to chronic IST via an expandable nitinol coring element, achieved substantial luminal gain and sustained patency in both patients.

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.