Treatment of complex thoracoabdominal or juxtarenal aortic aneurysms with a Multilayer stent.

In this issue of JEVT, 2 case reports focus on the treatment of (thoraco) abdominal aortic aneurysms with the Multilayer stent (Cardiatis SA, Isnes, Belgium). This stent, or so-called flow modulator, is a self-expanding device that has a 3-dimensional tube configuration consisting of multiple interconnected layers of braided metallic cobalt alloy wire. The optimal flow modulation through the layers of this stent has been determined at a 65% mean porosity rate. Due to a flow velocity reduction around 90% outside the stent (and inside the aneurysm sac), laminar flow to collateral arteries may be preserved while organized thrombus will be formed in the aneurysm itself. Multilayer stent diameters in the range of 22 to 44 mm are available for implantation in the thoracoabdominal aorta. Possible advantages of exclusion of complex (thoraco) abdominal aneurysms with the Multilayer flow modulator seem obvious. The flow modulator is an off-the-shelf device that does not need to be customized to a patient’s specific aortic anatomy; only the diameters of the proximal and distal part of the flow modulator have to be oversized 20% compared to the native aortic diameter. Due to the absence of fenestrations or branches, there is no need for time-consuming catheterization and additional stenting of side branches, which might save contrast volume, radiation exposure, time, additional equipment, and costs. However, it is too early to celebrate. During recent years, multiple articles have been published concerning the Multilayer stent, but most are case reports focusing on the treatment of visceral and renal artery aneurysms, with only short-term follow-up. In the largest series so far, Ruffino and coworkers at 12 different centers treated 19 patients with true visceral aneurysms. Initial technical success was achieved in all patients, but 2 stent thromboses occurred within 1 month. At 6 months, the stent patency and aneurysm sac thrombosis rates were 87.5%. Chocron and colleagues published the first case describing the implantation of a Multilayer stent to treat a thoracoabdominal residual type B dissection. Technical success was achieved, but follow-up was limited to a 3month postprocedure computed tomography (CT) scan. To date, the number of Multilayer flow modulators implanted to treat thoracoabdominal aortic aneurysm is unclear. Physicians are allowed to order and implant these stents outside any registry or trial, which might cause underreporting of initial complications and failures. Careful introduction of such an innovative and new technique should better be performed with limited release in a multicenter prospective trial or registry design, with at least 1-year follow-up including CT. In France, such a multicenter study is underway [Agence Française de Sécurité Sanitaire des Produits de Santé (AFSSAPS) protocol# 2008-A01396-49/ A], but results have not been published yet. Preoperative sizing and planning, as well as the procedure itself, can and must be optimized before unrestrained release takes place. Besides, stent-related complications (e.g., component separation, thrombosis, and migration)