News Column

Patent Issued for Low Profile Non-Symmetrical Stents and Stent-Grafts

June 2, 2014



By a News Reporter-Staff News Editor at Cardiovascular Week -- According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventors Chuter, Timothy A. M. (San Francisco, CA); Roeder, Blayne A. (Lafayette, IN), filed on December 22, 2011, was published online on May 20, 2014 (see also Cook Medical Technologies LLC).

The assignee for this patent, patent number 8728145, is Cook Medical Technologies LLC (Bloomington, IN).

Reporters obtained the following quote from the background information supplied by the inventors: "The present embodiments relate generally to stents and stent-grafts for use in body vessels to treat medical conditions.

"Stents may be inserted into an anatomical vessel or duct for various purposes. Stents may maintain or restore patency in a formerly blocked or constricted passageway, for example, following a balloon angioplasty procedure. Other stents may be used for different procedures, for example, stents placed in or about a graft have been used to hold the graft in an open configuration to treat an aneurysm. Additionally, stents coupled to one or both ends of a graft may extend proximally or distally away from the graft to engage a healthy portion of a vessel wall away from a diseased portion of an aneurysm to provide endovascular graft fixation.

"Stents may be either self-expanding or balloon-expandable, or they can have characteristics of both types of stents. Various existing self-expanding and balloon-expandable stent designs and configurations comprise generally symmetrical end regions including one or more apices formed of nitinol or another alloy wire formed into a ring. The apices commonly comprise relatively acute bends or present somewhat pointed surfaces, which may facilitate compression of the stent to a relatively small delivery profile due to the tight bend of the apices. Although having this advantage, in some situations, such relatively acute or pointed apices may be undesirable, in particular in vessel anatomies that are curved or tortuous such as, for example, the thoracic aorta.

"The thoracic aorta presents a challenging anatomy for stent grafts used to treat thoracic aneurysms or dissections. The thoracic aorta comprises a curve known as the aortic arch, which extends between the ascending thoracic aorta (closet to the heart) and the descending thoracic aorta (which extends toward the abdominal aorta). Thoracic stent grafts are used to exclude thoracic aortic aneurysms. A stent graft's ability to conform to the tortuous anatomy of the aortic arch is a major concern. Current designs sometimes lack the desired sealing ability at the proximal end of the stent graft (closest to the heart). Also, current thoracic devices present a relatively large profile which, with some patients' anatomies may be problematic. Finally, many current stents have relatively acute points that may prevent them from being used in the aortic arch for fear of undesirable interaction with the artery wall after an extended amount of time in the patient.

"Therefore, a generally nonsymmetrical stent having at least one relatively rounded apex that is less invasive in an expanded state than stents with more acute apices may alleviate the above problems, while providing an improved compliance to the aortic arch and increased radial force if used as a sealing and/or alignment stent, as well as a desirable ability to be crimped to a readily introducible diameter.

"As one particular example, type-A thoracic aortic dissection (TAD-A) is a condition in which the intimal layer of the ascending thoracic aorta develops a tear, allowing blood to flow into the layers of the aortic wall, causing the development of a medial or subintimal hematoma. TAD-A is associated with a strikingly high mortality rate (about one-fourth to one-half of victims die within the first 24-48 hours). The only current treatment for TAD-A is open surgery, where the chest is opened, the aorta is clamped, and a vascular prosthesis is sewn in place. Operative mortality rate for this procedure may be around 10%. Endovascular treatment of TAD-B (which affects the descending thoracic aorta) has been effective in reducing short-term and longer term mortality. Therefore, it is desirable to provide an endovascular device configured to address the anatomic challenges of the thoracic aorta."

In addition to obtaining background information on this patent, NewsRx editors also obtained the inventors' summary information for this patent: "Various stents and stent-grafts for treatment of medical conditions are disclosed. In one embodiment, a stent-graft comprises a graft and first and second stents. The first stent comprises a plurality of proximal apices, a plurality of distal apices, and a plurality of generally straight portions disposed between the plurality of proximal and distal apices. The second stent comprises a plurality of proximal apices, a plurality of distal apices, and a plurality of generally straight portions disposed between the plurality of proximal and distal apices.

"In one embodiment, the series of distal apices of the first stent are each disposed distal to the proximal end of the graft, and the series of proximal apices of the first stent are each disposed proximally beyond the proximal end of the graft. Additionally, the series of distal apices of the second stent are each disposed distal to the proximal end of the graft, and the series of proximal apices of the second stent are each disposed proximally beyond the proximal end of the graft.

"The first stent may comprise a first uniform segment, and the second stent may comprise a second uniform wire segment. In one example, the first uniform segment comprises portions disposed both internal and external to the second uniform wire segment.

"In one embodiment, each of the proximal apices of the first stent may be circumferentially offset from each of the proximal apices of the second stent. Further, each of the distal apices of the first stent may be circumferentially offset from each of the distal apices of the second stent.

"In one exemplary embodiment, the first stent and the second stent comprise identical geometries. At least one distal apex of the first stent may comprise a first curved portion having a first radius of curvature, and at least one proximal apex of the first stent may comprise a second curved portion having a second radius of curvature, where the second radius of curvature is greater than the first radius of curvature. Similarly, at least one distal apex of the second stent comprises a third curved portion having a third radius of curvature, and at least one proximal apex of the second stent comprises a fourth curved portion having a fourth radius of curvature, where the fourth radius of curvature is greater than the third radius of curvature.

"Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims."

For more information, see this patent: Chuter, Timothy A. M.; Roeder, Blayne A.. Low Profile Non-Symmetrical Stents and Stent-Grafts. U.S. Patent Number 8728145, filed December 22, 2011, and published online on May 20, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=107&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=5327&f=G&l=50&co1=AND&d=PTXT&s1=20140520.PD.&OS=ISD/20140520&RS=ISD/20140520

Keywords for this news article include: Angiology, Technology.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Cardiovascular Week


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