Stent self-expanding

Self-expanding stents with a higher radial force (e.g., WingSpan, Boston Scientific Corp.) will probably play a key role in acute stroke cases related to intracranial atherosclerotic disease. Antegrade flow is essential for the maintenance of vascular patency, as particularly evident in patients with severe proximal stenoses who commonly develop rethrombosis after vessel recanalization. Furthermore, stenting of the proximal vessels may be required in order to gain access to the intracranial thrombus with other mechanical devices or catheters. In a recent series, 23 of 25 patients (92%) with acute n = 15) or subacute n = 10) ICA occlusions were successfully revascularized with this technique. " ... 

Sauvageau E, Levy EL Self-expanding stent-assisted middle cerebral artery recanalization technical note. Neuroradiology 2006 48 405 08. 

Henkes H, Miloslavski E, Lowens S, Reinartz J, Liebig T, Kuhne D. Treatment of intracranial atherosclerotic stenoses with balloon dilatation and self-expanding stent deployment (WingSpan). Neuroradiology 2005 47 222-228. 

Wholey MH, Tan WA, Eles G, Jarmolowski C, Cho S, A comparison of balloon-mounted and self-expanding stents in the carotid arteries immediate and long-term results of more than 500 patients, J Endovasc Ther 2003 10 171-181,... 

Lubicz B, Leclerc X, Levivier M et al. Retractable self-expandable stent for endovascular treatment of widenecked intracranial aneurysms prehminary experience. Neurosurgery. 2006 58 451-457 discussion 451-457... 

Zaidat OO, Wolfe T, Hussain SI et al. Interventional acute ischemic stroke therapy with intracranial self-expanding stent. Stroke. 2008 39 2392-2395... 

Dabus G, Nogueira RG. Empty microcatheter technique for the deployment of a self-expanding stent to treat refractory middle cerebral artery occlusion in the setting of severe proximal tortuosity. J Neuroimaging. 2009 19 164-168... 

As the majority of patients are still not suitable for radical treatments due to age, physiologic status, or advanced disease, good palliation with minimal morbidity and mortality is important. Patients suffering dysphagia may benefit from intubation of strictures with insertion of rigid plastic tubes or self-expanding stents. Simple dilation offers short-term relief but does have significant risk of perforation. Some patients may benefit from chemotherapy or radiation therapy. 

Fig. 7.12. a A 9.6-year-old boy with a split liver transplantation (segments II and III). The patient was admitted to the paediatric intensive care because of severe haematemesis. The fluoroscopy image shows the TIPS catheter (arrow) placed within the portal vein. Multiple collateral vessels are shown (curved arrow), b After dilation of the puncture tract, two self-expandable stents (Smart diameter 9 mm.. Cordis, Johnson Johnson Medical N.V., Belgium) were placed. Angiography shows that the collaterals have collapsed and that the primary flow direction is through the TIPS, c Measurements of intravascular pressures shows the gradient to be 8 mm Hg, well below the threshold level of 15 mm Hg... 

L. Xue, S. Dai, Z. Li, Biodegradable shape-memory block copolymers for fast self-expandable stents, Biomaterials 31 (2010) 8132-8140. 

Althaus SJ, Keskey TS, Harker CP, Coldwell DM (1996) Percutaneous placement of self-expanding stent for acute traumatic arterial injury. J Trauma 41 145-148... 

Fig. 7.3a,b. Hepatic arteriogram in a 26-year-old man with a small inoperable neuroendocrine tumour in the head of his pancreas. The papilla of Vater could not be accessed at ERCP and he underwent a percutaneous stenting procedure at which two self-expanding stents were inserted (lower arrowheads) apparently side by side (a). 12 hours later repeat ERCP revealed a significant haemorrhage from the papilla. The angiogram revealed a segment 4 arterial pseudoaneurysm (upper arrowheads) which was embolized successfully with coils (b)... 

Stents can be divided into two main groups on the basis of the method of expansion. Balloon-expandable stents either arrive premounted on a balloon angioplasty catheter or are mounted by the doctor prior to the procedure. A balloon catheter with inflation apparatus is shown in Fig. 20.3. While mounted, the stent is moved into place and the balloon inflated to expand the stent to the desired diameter. Figure 20.4 illustrates the placement and inflation procedure for balloon-expandable stents. In contrast, self-expanding stents come premounted or sheathed. Once deployed to the treatment area, the sheath is pulled back, allowing the stent to expand to its predetermined diameter. Balloon-expandable stents can be further subdivided into slotted-tube and coil-based designs (Oes-terle et al., 1998). 

In the periphery, the siroUmus-coated cordis self-expandable stent (SIROCCO) trial, a randomized, donble-bhnd study comparing sirolimus eluting stents to nitinol bare metal stents in patients with chronic limb ischemia caused by superficial femoral artery occlusions or stenoses, reported no difference between drag elntmg and bare metal stents. Both stent types improved the arterial brachial indices and claudication symptoms, and both stent types demonstrated similarly low restenosis rates (22.9% for sirolimus eluting stents vs 21.1% for nitinol bare metal stents p>0.05)... 

Nowadays there are several self expanding stents specifically designed for intracranial use available. These stents are extremely flexible and access through tortuous vessels is facilitated. Even distal arteries can be reached easily. Since they are not balloon mounted the risk of damaging the artery is reduced. 

Wanke I, Doerfler A, Schoch B, Stolke D, Forsting M (2003) Treatment of wide-necked intracranial aneurysms with a self-expanding stent system initial clinical experience. AJNR Am J Neuroradiol 24 1192-1199 Wanke I, Doerfler A, Goericke S, Gizewski ER, Sandalcioglu... 

Sanyika C, Corr P, Haffejee A (1999) Palliative treatment of oesophageal carcinoma - efficacy of plastic versus self-expandable stents. SAMJ 89 640-643 Saxon RR, Barton RE, Rosch J (1994) Complications of oesophageal stenting and balloon dilatation. Semin Intervent Radiol 11 276-282... 

Due to the development of newer self-expanding stents, which combine the flexibility of the tantalum stent with the strength to oppose compression of stainless steel stents, the Strecker tantalum stent is no longer produced. 

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