Endovascular Management of Nonmalignant Iliocaval Venous Lesions

In vivo evaluation of safety and performance of a tapered nitinol venous stent with inclined proximal end in an ovine iliac venous model

A tapered stent with inclined proximal end is designed for fitting the iliac anatomically. The aim of the present study was to evaluate the safety and performance of the new stent in ovine left iliac veins. The experiment was performed in 30 adult sheep, and one nitinol-based VENA-BT® iliac venous stent (KYD stent) was implanted into each animal's left common iliac vein. Follow-up in all sheep consisted of angiographic, macroscopic, and microscopic examinations at Day 0 (< 24 h), Day 30, Day 90, Day 180 and Day 360 post-stenting (six animals per each time-point). 30 healthy ~ 50 kg sheep were included in this study and randomly divided into five groups according to the follow-up timepoint. All stents were implanted successfully into the left ovine common iliac vein. No significant migration occurred at follow-up. There is no statistically significant difference between the groups (p > 0.05), indicating no serious lumen loss occurred during the follow-up period. Common iliac venous pressure was further measured and the results further indicated the lumen patency at follow-up. Histological examinations indicated that no vessel injury and wall rupture, stent damage, and luminal thrombus occurred. There was moderate inflammatory cell infiltration around the stent in Day-0 and Day-30 groups with the average inflammation score of 2.278 and 2.167, respectively. The inflammatory reaction was significantly reduced in Day-90, Day-180 and Day-360 groups and the average inflammation scores were 0.9444 (p < 0.001, Day-90 vs Day-0), 1.167 (p < 0.001, Day-180 vs Day-0) and 0.667 (p < 0.001, Day-90 vs Day-0), respectively. The microscopic examinations found that the stents were well covered by endothelial cells in all follow-up time points. The results suggested that the KYD stent is feasible and safe in animal model. Future clinical studies may be required to further evaluate its safety and efficacy.

Double-barrel iliocaval reconstruction using closed-cell dedicated venous stents

OBJECTIVE

Double-barrel iliocaval reconstruction is performed by deploying two stents simultaneously in a side-by-side, or "double-barrel," configuration in the inferior vena cava (IVC) with extension into the bilateral common iliac veins. The aim of this study was to examine the outcomes of double-barrel reconstruction using closed-cell dedicated venous stents for the treatment of iliocaval deep venous thrombosis and iliac vein compression syndrome.

METHODS

All endovascular procedural reports comprising vascular surgery and interventional radiology operators from a single urban academic hospital between May 1, 2019, and April 30, 2021, were retrospectively searched. A cohort of 22 consecutive patients who underwent double-barrel iliocaval stenting with closed-cell dedicated venous stents for chronic or acute-on-chronic iliocaval venous disease without prior endovascular iliocaval repair was identified. Baseline characteristics, procedural data, and patient outcomes were determined via a manual review of preprocedure clinical notes, diagnostic imaging studies, procedure notes and images, and follow-up clinical notes.

RESULTS

The median (range) age was 59 (27-81) years, and the cohort consisted of 59.1% female. The most common presenting symptoms of venous disease were lower extremity swelling (90.9%) and pain (50.0%). CEAP clinical classification was C3 in 86.4% of patients, whereas the remainder had C4 disease. Most patients (72.7%) had post-thrombotic syndrome, 22.7% had a nonthrombotic iliac vein lesion, and one patient (4.5%) had the congenital absence of the infrarenal IVC. A total of 40.9% of patients had a pre-existing IVC filter at the time of treatment. Six of the 22 patients underwent concurrent pharmacomechanical thrombectomy during the index iliocaval reconstruction and stenting procedure. The number of stents placed ranged from 2 to 5. With a mean follow-up period of 7.1 months, ranging from 12 days to 16.7 months, the freedom from reintervention rate was 90.9%. Twenty of 22 patients achieved subjective improvement or resolution of symptoms. The major adverse event rate was 9.1%, as two patients had access site complications requiring intervention.

CONCLUSIONS

Double-barrel iliocaval reconstruction with closed-cell dedicated venous stents for the treatment of post-thrombotic syndrome or iliac vein compression syndrome is technically feasible and clinically effective with a low reintervention rate.

Extravascular reconstruction of a congenitally absent inferior vena cava

Congenital absence of the inferior vena cava is an uncommon venous anomaly with treatment algorithms consisting of predominately medical management. We present a case of a 36-year-old man with venous ulcers who had failed conservative treatment for recurrent venous ulcers. From a catheter directed approach, we were able to develop an extravascular retroperitoneal space and perform an iliocaval reconstruction with Wallstents. At 1-year postoperatively, his leg pain and edema had resolved, and had achieved resolution of his venous ulceration.

PERFORMANCE TEST AND EXPERIMENTAL STUDY OF SPECIAL STENT FOR TREATMENT OF ILIAC VEIN STENOSIS

Objective: Animal experiments and clinical trials were carried out to evaluate the efficiency of a new stent for the treatment of iliac vein stenosis. Methods: The new iliac vein stent and the control stent were implanted, respectively, into the 12 experimental pigs. Digital Subtraction Angiography was done separately at the same day, 14th, 30th, 60th and 90th day after stent implantation to observe the stent deployment. One patient was implanted with a new iliac vein stent. Digital subtraction angiography (DSA) was done after the operation to calculate the lumen loss value and lumen loss rate of the stent and evaluate the performance of the new iliac vein stent at 12 months of follow-up. Results: The mechanical experiment and finite element analysis of the stent proved that the radial support force of the new stent is significantly better than that of the control stent. In animal experimental verification, both groups of stent were released satisfactorily during implantation. No obvious stent displacement was found at each time point. The patency rate of stents was 100%. Except for a small amount of old thrombosis in the stent in the control group, no other stents were found in that condition. The diameter of the stent lumen was retracted in different degrees in both groups after the operation, but no significant statistical difference was found in the comparison of the stent lumen loss rate at each relative inspection day. Conclusion: The new nickel-titanium alloy iliac vein stent has excellent radial support performance, which may be an ideal iliac vein stent.

Anticoagulation reduces iliocaval and iliofemoral stent thrombosis in patients with cancer stented for nonthrombotic venous obstruction

OBJECTIVE

To identify factors associated with venous stent thrombosis in patients with cancer treated for nonthrombotic iliocaval or iliofemoral venous obstruction.

METHODS

We performed a retrospective review of relevant imaging and medical records from 30 consecutive patients with cancer treated at a single center who underwent venous stent placement for nonthrombotic iliocaval or iliofemoral venous obstruction between 2008 and 2018. Follow-up imaging was used to assess stent patency. Variables examined included patient demographics, cancer type, stent characteristics, anticoagulant, and antiplatelet medications and complications of treatment.

RESULTS

Overall primary stent patency was 83% (25/30). The median follow-up period was 44 days (range, 3-365 days). Ten percent of patients occluded owing to in-stent thrombosis and 7% owing to tumor compression of the stent without thrombosis. Therapeutic poststent anticoagulation with enoxaparin, warfarin, or a factor Xa inhibitor was initiated in 87% of the patients. Stent thrombosis occurred in one patient in the anticoagulation group (4%) at 50 days. Stent thrombosis occurred in two patients in the nonanticoagulation group (50%), one at 9 days and the other at 91 days. Anticoagulation was found to be protective against stent thrombosis in this population (hazard ratio, 0.015; P = .011). No statistically significant associations were found among the remaining variables. One patient in the anticoagulation group experienced major bleeding (1/26 [4%]).

CONCLUSIONS

Iliocaval and iliofemoral stent placement for nonthrombotic malignant venous obstruction is safe with favorable primary patency rates. Therapeutic anticoagulation is associated with less stent thrombosis in patients with cancer stented for nonthrombotic iliocaval and iliofemoral venous obstruction.

Venous Compression Syndromes

Venous compression syndromes occur due to extrinsic compression causing complications of venous hypertension or venous thrombosis. This review focuses on 4 venous compression syndromes involving the left common iliac vein, subclavian vein, left renal vein, and popliteal vein. Clinical presentation, diagnostic methods, and management options are reviewed. When properly diagnosed and treated, long-term consequences can be avoided.

Stent Compression in Iliac Vein Compression Syndrome Associated with Acute Ilio-Femoral Deep Vein Thrombosis

OBJECTIVE

This study was conducted to evaluate stent compression in iliac vein compression syndrome (IVCS) and to identify its association with stent patency.

MATERIALS AND METHODS

Between May 2005 and June 2014, after stent placement for the treatment of IVCS with acute ilio-femoral deep vein thrombosis, follow-up CT venography was performed in 48 patients (35 women, 13 men; age range 23-87 years; median age 56 years). Using follow-up CT venography, the degree of the stent compression was calculated and used to divide patients into two groups. Possible factors associated with stent compression and patency were evaluated. The cumulative degree of stent compression and patency rate were analyzed.

RESULTS

All of the stents used were laser-cut nitinol stents. The proportion of limbs showing significant stent compression was 33%. Fifty-six percent of limbs in the significant stent compression group developed stent occlusion. On the other hand, only 9% of limbs in the insignificant stent compression group developed stent occlusion. Significant stent compression was inversely correlated with stent patency (p < 0.001). The median patency period evaluated with Kaplan-Meier analysis was 20.0 months for patients with significant stent compression. Other factors including gender, age, and type of stent were not correlated with stent patency. Significant stent compression occurred most frequently (87.5%) at the upper end of the stent (ilio-caval junction).

CONCLUSION

Significant compression of nitinol stents placed in IVCS highly affects stent patency. Therefore, in order to prevent stent compression in IVCS, nitinol stents with higher radial resistive force may be required.

May-Thurner syndrome and other obstructive iliac vein lesions: meaning, myth, and mystery

Acute and chronic venous disorders of the lower extremities affect millions of people and cause substantial disability. Long ago, surgeons and pathologists identified the presence of 'spur-like' abnormalities of the left common iliac vein; these abnormalities were hypothesized to result from compression and/or irritation from the adjacent crossing right common iliac artery. In the 1990s, physicians, starting to perform catheter-directed thrombolysis to treat extensive deep vein thrombosis (DVT), observed that about 50% of patients had an iliac vein stenosis. Vascular physicians have become aware of the occasional patient with otherwise-unexplained extremity swelling and/or pain but without a DVT history who is subsequently found to have an iliac vein abnormality. These 'lesions' have been hypothesized to elevate ambulatory venous pressures and thereby produce lower-extremity symptoms, increase the risk of initial and recurrent DVT episodes, and increase the risk of treatment failure with medical and endovascular therapies for thrombotic and non-thrombotic venous conditions. As a result, many practitioners now actively seek iliac venous obstructive 'lesions' when evaluating patients with known or suspected venous disease. However, for many patients, it continues to be unclear what degree of obstruction to venous blood flow is being caused by such lesions, how clinically significant they are, how much emphasis should be placed on identifying them, and when they should be treated. This article seeks to improve the knowledge base of vascular practitioners who make clinical decisions about the diagnosis and treatment of obstructive iliac vein lesions.