Venous Intervention

First-Year Experience With a Dedicated Venous Stent in a Community Hospital Vascular Interventional Practice

Matthew Tiede, MD, Vascular Interventional Radiology, Metro Health/University of Michigan Health, Wyoming, Michigan  

Matthew Tiede, MD, Vascular Interventional Radiology, Metro Health/University of Michigan Health, Wyoming, Michigan  

Venous disease is a significant burden on the global medical system. It encompasses a variety of acute and chronic disease processes of both the deep and superficial vein system. Chronic venous insufficiency accounts for as much as 2% of Western healthcare budgets in multiple papers and affects as many as 25 million Americans.1,2

According to the NHS, up to 70-90% of all lower extremity ulcerations have a venous component.3 In the United States, the Centers for Disease Control (CDC) states there are 900,000 cases each year of venous thromboembolism, resulting in 60-100,000 deaths and 30% of whom develop some degree of venous insufficiency.4

One year ago, the world of venous interventions changed dramatically with introduction of novel, dedicated venous stents, Venovo (Becton-Dickinson [BD]) and Vici (Boston Scientific). Prior to this, several off-label stents were available in sizes up to 14 mm, but the only stent on the market large enough to treat diseased central veins was the Wallstent (Boston Scientific). In addition to its large sizing, the Wallstent, with its closed cell design, also offered flexibility and the ability to be deployed in a tapered fashion, both desirable traits in the venous realm. However, due to this design, the Wallstent was also plagued with imprecise and often unpredictable positioning at placement. Long-term failures were also seen, related to the braided closed cell design, which caused inadequate radial strength at the ends of the stent, particularly in still-diseased vessels. Attempts to manage these difficulties with positioning and patency of the stent ends were made with addition of a Z-stent (Cook Medical) or other higher radial force stent at the end of the Wallstent.

BD’s Venovo stent is designed to address these concerns. This stent’s open-cell, peak-to-valley design is intended to offer improved radial strength while maintaining flexibility and allowing for precise, predictable placement. 

Our Experience With Use of the Venovo Stent

At its introduction, our department chose to primarily use the Venovo stent as we built our venous intervention practice. In an era of cost control and utilization management, we did not have access to both new stents to allow for direct comparison, but instead, used a historical comparison of previous interventions. 

Venovo stent outcomes were validated with 1- and 2-year data5 from the sponsored VERNACULAR trial. Primary patency was published at 88% and 83%, respectively. Zero percent stent fractures were recorded, including 15 stents placed across the inguinal ligament. Target vessel outcome was better in non-thrombotic iliac vein lesions (NIVL) treatment than in post-thrombotic syndrome (PTS) patients at all points of interest.

Our patient population is somewhat unique, as we are building a new practice in an environment with established endovascular, interventional cardiology, interventional nephrology, and vascular surgery practices, with whom we are collegial. We see very little acute deep vein thrombosis (DVT) or early sequelae thereof. Most of our patients have complex disease, with primary presentations being chronic dialysis with central obstruction, chronic iliac or ilio-caval occlusion, PTS, and chronic venous ulcers. As such, these patients often require complex interventions involving multiple vessels. A minority of our patients present to us with simple May-Thurner or early obstructive disease. 

In the first 12 months, we used 86 Venovo stents to treat 94 diseased vessels in 46 patients. This includes 5 patients with PTS involving iliofemoral veins requiring intervention across the inguinal ligament. Several patients did have a diagnostic venogram for planning purposes prior to intervention. Intravascular ultrasound (IVUS) was used with each intervention for procedure guidance. The most common stent sizes used were varying lengths of 14 mm and 16 mm, as would be expected in central veins.6 

We experienced 100% technically successful deployment with initial patency. We have 1-11 months of clinical and/or imaging follow-up. No fractures or stent migration have been identified. We have had a single target lesion reintervention on a dialysis patient with bilateral brachiocephalic vein occlusion (Figures 1A-B). This was due to incomplete overlap of stents during recanalization that resulted in a small inter-stent gap. It ultimately became a flow-limiting stenosis, requiring additional stent placement. Some patients have also required second target site interventions. The majority of our patients have shown clinical improvement. One PTS patient has had no measurable improvement and symptoms were felt to be of neurologic origin. Unfortunately, 6 patients died due to other comorbidities such as cancer and complications of chronic renal failure. The other patients all show varying degrees of symptom improvement from partial to complete resolution. Particularly, the wound center patients have each shown improved wound healing. The only procedure-related major adverse effect was a subclavian vein rupture at the time of post dilation during a recanalization of a chronic occlusion due to pacemaker wires. It was successfully resolved with a covered stent graft. 

Stent Platform, Design, and Sizing

The Venovo stent platform is a triaxial roller wheel release versus the pin-pull deployment of either the Wallstent or Vici. The nitinol open-cell design assures that the length of the stent is accurate both before and after deployment. These features, when combined with intravascular ultrasound (IVUS) and venography planning, allow for very precise measurement and placement. Unlike the Elgiloy braided closed cell design of the Wallstent, the Venovo stent does not change length with varied post dilation diameter. Stent size is chosen to closely match a healthy landing zone in the vessel based on IVUS area measurements or normal reference values.6 Correct sizing is important with this stent, as oversizing, with the Venovo’s higher radial strength, has been reportedly associated with prolonged post intervention pain. The Venovo has a 3 mm flare at each end that prevents migration and allows full wall apposition, whether deployed antegrade or retrograde. An additional benefit of the 3 mm flare is that stent sizes can be stepped down. For instance, a 14 mm stent can be safely deployed in an external iliac vein after a 16 mm stent has been placed in the common iliac. This downsizing was not possible with straight stent design due to risk of migration and incomplete apposition. 

Related to sizing, it is worth noting that, especially in the left common iliac vein, stent length can be underestimated due to straightening of the vessel course by a stiff guide wire or with the IVUS catheter in place. The radiographic appearance may be shorter than expected after deployment due to the stent conformability to venous anatomy. Care must also be taken to make sure one is not holding the retractable inner catheter during deployment rather than the fixed outer catheter, as it can result in the stent being “pulled” farther away from the access site (it can be avoided using a longer access sheath with triaxial systems). Venovo stents are also easily deployed simultaneously as kissing stents at vessel confluences such as the iliac carina (Figures 2A-B). 

Conclusion

Our initial experience with the Venovo as our primary stent for treatment of venous disease has been very positive. Initial clinical outcomes have been on par with previous techniques and with expectations based on results from the VERNACULAR study. The Venovo stent’s deployment mechanism and stent design allow for precise placement at target lesions (Figures 3A-B). With a wide matrix of sizes (10-20 mm x 40-160 mm) in conjunction with other large-diameter options on the market, treatment options are available for the entirety of the central venous anatomy. With this stent, and the growing interest and investment in the world of venous intervention, the future is bright for our field and our patients. 

Disclosures: Dr. Tiede reports no conflicts of interest regarding the content herein.

Dr. Tiede can be contacted at matthew.tiede@metrogr.org.

References
  1. Rabe E, Pannier F. Societal costs of chronic venous disease in CEAP C4, C5, C6 disease. Phlebology. 2010; 25 Suppl 1: 64-67.
  2. Barnes GD, Gafoor S, Wakefield T, Upchurch GR Jr, Henke P, Froehlich JB. National trends in venous disease. J Vasc Surg. 2010 Jun; 51(6): 1467-1473.
  3. Venous leg ulcer. National Health Service UK. Updated January 11, 2019. Available online at https://www.nhs.uk/conditions/leg-ulcer/. Accessed May 18, 2020.
  4. Data and statistics on venous thromboembolism. Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/ncbddd/dvt/data.html. Accessed May 18, 2020.
  5. Almeida JI. Latest Update from the VERNACULAR trial. Presented at: International Symposium on Endovascular Therapy (ISET); Jan. 23, 2020; Hollywood, Fla. Available online at https://www.vasculardiseasemanagement.com/abstract/latest-update-vernacular-trial. Accessed May 26, 2020.
  6. Raju S, Buck WJ, Crim W, Jayaraj A. Optimal sizing of iliac vein stents. Phlebology. 2018 Aug; 33(7): 451-457.