Venous Stenting

Excerpt

Awareness in the treatment of venous disorders through the use of stents has increased over the past decade. Venous stenting is recognized as a possible treatment to help assist patients with symptomatic iliocaval venous obstruction (ICVO) as an alternative to conventional surgery. ICVO contributes to chronic venous insufficiency and chronic venous hypertension. Symptoms of ICVO include venous claudication, chronic edema and/or venous ulceration, and other manifestations of post-thrombotic syndrome.

Women and patients with a history of deep venous reflux diagnosed on duplex scans have a higher incidence of ICVO. ICVO may be secondary to iliofemoral deep vein post-thrombotic obstruction (PTO) or non-thrombotic iliac vein lesions (NIVLs, formerly referred to as May-Thurner syndrome).

Hemodynamically significant ICVO may compromise the effectiveness and even causes worsening of symptoms with routine compression therapy and exercise for limb swelling. The use of stenting procedures to treat ICVO, including involvement into the inferior vena cava, has acceptable patency rates and reduction in symptoms in most patients. In a published study with over 1500 patients, iliac vein stenting for ICVO was considered being safe with high patency rates of up to 5 years. Improvement in pain, ulceration, and limb swelling were noted. A follow-up meta-analysis of 37 studies demonstrates good technical success, with minimal periprocedural complications and symptom relief at final follow-up for 5 years. Complication rates are less than 1% for major bleeding, pulmonary embolism, and mortality, with 1.0% to 6.8% for early stent thrombosis.

The initial use of self-expanding stents for the treatment of ICVO employs an endoprosthesis stent consisting of a braided, self-expanding stent composed of cobalt, chromium, and nickel alloy. Early venous stents comprise large diameters, radial force, compression, and fracture resistance. However, its deployment accuracy could be imprecise due to stent foreshortening. The radial force is only present in the body, and thus the stent could collapse at the ends due to the Poisson effect of biomechanical forces. The point of maximal compression in patients with NIVL is between the left common iliac vein (CIV) and the inferior vena cava (IVC). These factors can make it difficult to place the stent with accuracy.

Most initial venous stents were not designed for use in the venous system. Initial stent development focused on addressing these challenges by increasing the crush resistance needed in venous stents. Several venous stents have received FDA approval after investigational device exemption trials. These nitinol stents differ in whether they consist of a closed-cell or open-cell configuration. The mechanism of deployment, whether coaxial or triaxial, also varies between the stents. Except for the recent recall of two stents secondary to the improper deployment, these trials demonstrate acceptable efficacy and safety.

Based on prior consensus clinical practice guidelines, iliac stenting assists in significantly increased ulcer healing. Primary treatment of iliocaval stenting for obstructive disease without superficial truncal reflux is suggested as first-line treatment in a symptomatic patient with skin or subcutaneous changes, healed or active ulcers.