The innovation of Multilayered Aneurysm Repair Stents (MARS) in treatment of thoraco-abdominal aneurysms

Background Morbidity and mortality from Thoraco-abdominal aneurysms are tremendous. Preoperative assessment in predicting cardiac and pulmonary risk factors in order to reduce cardiopulmonary complications, paraplegia, and renal failure are the main determinants of postoperative mortality and therefore gained substantial attention during the last decades.(Jacobs MJ et al.,2007) Left heart by-pass, CSF drainage and epidural cooling have significantly reduced the paraplegia rates. Monitoring MEPs allowed detection of cord ischemia,(spinal cord ischemic injury, SCII) guiding aggressive surgical strategies to restore spinal cord blood supply and reduce neurological deficit. It’s believed that these protective measures should be included in the surgical protocol of TAAA repair type II cases. (Jacobs MJ et al.,2007) Renal and visceral ischemia can be reduced significantly by continuous perfusion during TAAA repair. (Jacobs MJ et al.,2007) Obviously endovascular modalities have been successfully applied in TAAA patients, the majority apart of hybrid procedures. Technological innovations will eventually cause a shift from open to minimal invasive surgical repair. (Jacobs MJ et al.,2007) The multilayer aneurysm repair system (MARS) is a flow modulator and part of the fluid smart© technology platform developed by Cardiatis, Isne-Belgium. The MARS is self-expanding and composed of multiple cobalt alloy interconnected braided layers the 3D geometrical configuration gurantees an optimal porosity range for stent from 2 to 50mm in diameter providing unique flow modulating features. The innovative multilayer flow modulating device offers a paradigm shift approach to the treatment of these complicated aneurysms by physiologically (rather than mechanically ) excluding aneurysms from the circulation, while keeping branches patent and preserving critical collateral circulation.(C.Vaislic et al.,2011) Its 3D geometrical and structural gives rise to several important hemodynamic and biological effects i.e, in a secular aneurysm it reduces the vortex velocity within the aneurysm sac creating a remodeled organized thrombus, it transforms turbulent flow into laminar flow preserving collateral circulation when over stenting collaterals or in a fusiform aneurysm, it accelerates and channels the flow into a branching aneurysm open branch enhancement and accelerates shear flow along the parent vessel, resulting in inhibition of intimal hyperplasia. (C.Vaislic et al.,2011) Theoretical basic principles of the device are very attractive and the most important of which is preserving the collaterals and improving their flow. Sac thrombosis and sac shrinkage don’t  usually occur immediately, several factors could play a role as collateral branches and this should be studied and determined preoperatively.(M.Henry,2011) Preliminary clinical results are satisfactory and promising but larger experience and longer follow up are still needed. (M.Henry,2011) Hypothesis The results of endovascular treatment for thoraco-abdominal aneurysms are now comparable with the open surgical procedure. However, endovascular repair in the thoraco-abdominal aorta has been limited due to the complexity of keeping the side branches (intercostals ,renal, visceral) perfused. Attempts are being made to adapt endoluminal stent-graft by using custom fenestrations and branched graft. While preliminary data showed concept feasibility, this technique is still investigational and requires highly skilled operator and custom made devices for each patient. Aim of the work 1- To study the availability of the new technique in management of TAAA. 2- To shed lights on the technique of deploying the new device. 3- To review the outcome and complications of this new device before introducing this technique as a standard utility. 4- To shed lights over the new evolving biomedical technology in vascular surgery This will be supported by the French STRATO trial and by a number of cases done at multi- european centers Keywords Thoraco-abdominal aneurysms, Multilayer Aneurysm Repair System (MARS) Intimal hyperplasia, Sac shrinkage, Sac thrombosis, Ischemia References 1- Jacobs MJ, Mommertz G, koeppel TA, Langer S, Nijenhuis RJ, Mess WH, Schurink GW. Surgical repair of TAAA. J Cardiovasc Surg Torino(2007) Feb; 48 (1) :49-58 2- C.Vaislic, A.Benjelloun ,J.-N.Fabiani, J.-F.Bonneville, S.Chocron. multilayered flow modulator treatment of thoraco-abdominal aortic aneurysms.Controversies and vascular updates (2011)JAN;74:443-449 3- M.Henry,MD. The Multilayer Stent. First human study.(2011), ISET presentation.