Renal artery stenting- A pictorial review of stent designs, indications and outcomes

Transcription

1 Renal artery stenting- A pictorial review of stent designs, indications and outcomes Poster No.: C-1644 Congress: ECR 2012 Type: Educational Exhibit Authors: C. Tingerides, S. McPherson, S. Puppala ; Leeds/UK, LEEDS/ UK Keywords: Kidney, Interventional vascular, Catheter arteriography, Stents, Biological effects, Arteriosclerosis DOI: /ecr2012/C Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 15

2 Learning objectives To gain an understanding of the different categories of stents available for use in the renal artery. The pros and cons of each category are presented with reference to their suitability for use in the treatment of different renal artery pathologies. Background The treatment of renal artery stenosis (RAS) is an evolving area with many controversies. Metal stents have been used for many years to treat patients with RAS and poorly controlled hypertension and/or renal insufficiency. Page 2 of 15

3 Fig. 1: Renal Artery Stenosis depicted on Digital Subtraction Angiography and MR Angiography. References: C. Tingerides; Department of Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UNITED KINGDOM Stents also have a role in other renal artery pathologies such as aneurysms and dissection. A number of different stent designs are available for use in the peripheral vessels. No single type is universally superior for all indications. Our aim is to present the Page 3 of 15

4 reader with a practical categorisation of stents available for use in the renal artery. The pros and cons of each category are also presented. Images for this section: Fig. 1: Renal Artery Stenosis depicted on Digital Subtraction Angiography and MR Angiography. Page 4 of 15

5 Fig. 2: An example of renal artery stenosis treated with a stent Page 5 of 15

6 Imaging findings OR Procedure details CATEGORIES OF STENTS Balloon-expanded stents: These are essentially expandable wire-mesh cylinders usually made of stainless steel (devices made of made of platinum, chromium cobalt or nitinol are also available). They are mounted on an angioplasty balloon and are advanced through the vascular system over guide wires. Once they are in position, they are deployed by inflating the balloon. Advantages: The excellent hoop strength makes this the preferred device for ostial lesions and therefore the preferred device to treat atherosclerotic renal artery stenosis. Balloon-expandable stents can be deployed with accuracy. This is again an advantage over other designs as precise deployment is of paramount importance in ostial lesions. Fig. 2: An example of renal artery stenosis treated with a stent References: C. Tingerides; Department of Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UNITED KINGDOM Page 6 of 15

7 The closed cell design used in these stents provides continuous scaffolding and superior strength to minimise the potential for plaque prolapse or restenosis. Disadvantages: The lack of flexibility is a disadvantage, as it makes vessel wall apposition difficult in an area of vessel size transition. In more recent models, a mesh with smaller cells and thinner struts is used to improve flexibility while preserving good radial strength. Fig. 3: Formula 418 Balloon-expandable stent References: Cook Medical Self-expanding stents: These stents are constructed of stainless steel or nitinol, a nickel titanium alloy. They are supplied compressed within a delivery catheter. Retraction of the delivery catheter allows the stent to expand to a predetermined size by a spring like action.self expanding stents are widely used in peripheral vessels but their use in renal ostial lesions is limited. Advantages: Page 7 of 15

8 These stents offer better flexibility and thus are the preferred devices for tortuous vessels. Disadvantages: Unlike balloon expandable stents, once deployed, self-expanding stents cannot be expanded further. Therefore a better device/target vessel size match is required. Fig. 4: An example of a self-expanding stent in the process of deployment (Wallstentboston scientific Although Wallstent endoprosthesis has been used in clinical trials, the manufacturer does not market it for use in renal arteries References: Boston scientific, cat=1762&mode=gallery Covered stents Page 8 of 15

9 Covered stents, or stent grafts, are metal tubes that have a polytetrafluoroethylene (PTFE) covering which is intended to replace the inner lining of the vessel. They can be balloon-expandable or self expanding. There are no studies into the use of covered stents for primary renal revascularisation. They are primarily used in the management of a ruptured renal artery or exclusion of a renal artery aneurism. We found one study were they were used for the treatment of restenosis following PTRA and stenting. Fig. 5: The VIABAHN Endoprosthesis is indicated for endovascular grafting of peripheral arteries. References: Vascular news BIBA Medical, 44 Burlington Road, Fulham, London, SW6 4NX. Page 9 of 15

10 FUTURE PERSPECTIVE Drug-eluting stents Drug-eluting stents aim to decrease intimal hyperplasia and restenosis by employing an internal coating, which provides controlled release of agents that block the activation of inflammatory cells and growth factors. No drug-eluting device currently holds CE or FDA approval for use in renal arteries. Bioabsorbable stents Biodegradable stents are a recent advancement endovascular therapy. They are made of polymers or metal alloys, with or without a drug coating. Theoretically, they have the potential to scaffold the artery to allow natural healing to take place, and then biodegrade. Several biodegradable coronary stents have entered into clinical trials. We could find no reports into the use of this technology in renal artery revascularization and no device is currently marketed for use in the renal arteries. Images for this section: Fig. 2: An example of renal artery stenosis treated with a stent Page 10 of 15

11 Fig. 3: Formula 418 Balloon-expandable stent Page 11 of 15

12 Fig. 4: An example of a self-expanding stent in the process of deployment (Wallstentboston scientific Although Wallstent endoprosthesis has been used in clinical trials, the manufacturer does not market it for use in renal arteries Page 12 of 15

13 Fig. 5: The VIABAHN Endoprosthesis is indicated for endovascular grafting of peripheral arteries. Page 13 of 15

14 Conclusion Endovascular revascularisation has expanded dramatically over the last thirty years due to continuing innovation. Restenosis however, remains the "achilles' heel" of this technique. The advent of balloon-expanded stents provided lower rates of restenosis compared with the previous technique of angioplasty alone. Advances in stent design, together with drug-eluting and bioabsorbable technologies may help achieve better results. Personal Information References Grüntzig A, Kuhlmann U, Vetter W, et al. Treatment of renovascular hypertension with percutaneous transluminal dilatation of a renal-artery stenosis. Lancet 1978;1: Weibull H, Bergqvist D, Bergentz SE, et al. Percutaneous transluminal renal angioplasty versus surgical reconstruction of atherosclerotic renal artery stenosis: A prospective randomized study. J Vasc Surg 1993;18: ; discussion Van de Ven PJ, Kaatee R, Beutler JJ, et al. Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: A randomised trial. Lancet 1999;353: Duerig T, Wholey M. A comparison of balloon and self-expanding stents. Min Invas Ther Allied Technol2002;(4): Leertouwer et al Stent placement for renal arterial stenosis: where do we stand? A meta-analysis. July 2000 Radiology, 216, Wilms GE, Peene PT, Baert AL, et al. Renal artery stent placement with use of the Wallstent endoprosthesis. Radiology 1991; 179: Hennequin LM, Joffre FG, Rousseau HP, et al. Renal artery stent placement: long-term results with the Wallstent endoprosthesis. Radiology1994; 191: Virginia Gaxotte, Brigitte Laurens, Stéphan Haulon, Christophe Lions, Claire Mounier-Véhier and Jean-Paul Beregi (2003)Multicenter Trial of the Jostent Balloon-Expandable Stent-Graft in Renal and Iliac Artery Lesions. Journal of Endovascular Therapy: April 2003, Vol. 10, No. 2, pp Zähringer M et al Sirolimus-eluting versus bare-metal low-profile stent for renal artery treatment(great Trial): angiographic follow-up after 6 months and clinical outcome up to 2 years. J Endovasc Ther Aug;14(4): Page 14 of 15

15 10. Garg S, Serruys P Biodegradable stents and non-biodegradable stents. Minerva Cardioangiol Oct;57(5): Page 15 of 15