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Patent Application Titled "Methods of Manufacture of Bioresorbable and Durable Stents with Grooved Lumenal Surfaces for Enhanced...

June 5, 2014



Patent Application Titled "Methods of Manufacture of Bioresorbable and Durable Stents with Grooved Lumenal Surfaces for Enhanced Re-Endothelialization" Published Online

By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventor Pacetti, Stephen D. (San Jose, CA), filed on January 17, 2014, was made available online on May 22, 2014.

The assignee for this patent application is Abbott Cardiovascular Systems Inc.

Reporters obtained the following quote from the background information supplied by the inventors: "This invention relates to methods of manufacturing medical devices, in particular, stents.

"This invention relates to manufacturing of implantable medical devices. These devices include, but are not limited to, radially expandable endoprostheses, that are adapted to be implanted in a bodily lumen. An 'endoprosthesis' corresponds to an artificial device that is placed inside the body. A 'lumen' refers to a cavity of a tubular organ such as a blood vessel. A stent is an example of such an endoprosthesis. Stents are generally cylindrically shaped devices that function to hold open and sometimes expand a segment of a blood vessel or other anatomical lumen such as urinary tracts and bile ducts. Stents are often used in the treatment of atherosclerotic stenosis in blood vessels. 'Stenosis' refers to a narrowing or constriction of a bodily passage or orifice. In such treatments, stents reinforce body vessels and prevent restenosis following angioplasty in the vascular system. 'Restenosis' refers to the reoccurrence of stenosis in a blood vessel or heart valve after it has been treated (as by balloon angioplasty, stenting, or valvuloplasty) with apparent success.

"Stents are typically composed of scaffold or scaffolding that includes a pattern or network of interconnecting structural elements or struts, formed from wires, tubes, or sheets of material rolled into a cylindrical shape. This scaffolding gets its name because it physically holds open and, if desired, expands the wall of the passageway. Typically, stents are capable of being compressed or crimped onto a catheter so that they can be delivered to and deployed at a treatment site.

"Delivery includes inserting the stent through small lumens using a catheter and transporting it to the treatment site. Deployment includes expanding the stent to a larger diameter once it is at the desired location. Mechanical intervention with stents has reduced the rate of restenosis as compared to balloon angioplasty.

"Stents are used not only for mechanical intervention but also as vehicles for providing biological therapy. Medicated stents provide biological therapy through local administration of a therapeutic substance. A medicated stent may be fabricated by coating the surface of either a metallic or polymeric scaffolding with a polymeric carrier that includes an active or bioactive agent or drug. A polymeric scaffolding may also serve as a carrier of an active agent or drug.

"These drug eluting stents (DES) are used in order to revascularize occluded regions of the coronary vasculature. Current DES work well yielding single digits of major adverse cardiac events (MACE) and restenosis at one year for a majority of patients. Ongoing issues are restenosis, an iatrogenic disease caused by the intervention itself, and thrombosis. While the onset of restenosis is gradual, stent thrombosis can occur suddenly and the outcome is completely contrary to the intent of revascularization. Stent thrombosis can occur at any time. However, thrombosis which occurs in the first 30 days (subacute) is thought to be due more to procedural issues, blood hypercoaguability, poor stent placement and apposition, and perhaps drug effects. At longer time points, the goal is for the vessel to heal and re-endothelialize to avoid late stent thrombosis occurring beyond 30 days. The ongoing rates of late stent thrombosis have been measured as 0.36 to 0.6% out to five years. Garg S, Serruys P. Coronary Stents. J Amer Coll Cardiol 2010; 56(10): Suppl S. S1.

"The only truly non-thrombogenic surface is healthy endothelium. Consequently, rapid and complete re-endotheliazation has always been a goal for metallic, drug eluting, and bioresorbable stents in order to reduce and eliminate late stent thrombosis. As all of the drugs presently used in DES inhibit the proliferation of endothelial cells, the interest in promoting endothelial cell growth remains high. After stenting, re-endotheliatization is achieved primarily by migration of endothelial cells from adjacent arterial areas of intact endothelium. Haudenschild C C, Schartz S M. Lab Invest 1979; 41:407-418; Rogers C, Tseng D Y, et al. Circ Res 1999; 84:378-383. Based on this mechanism, extensive work has been done to understand factors which affect endothelial cell migration. For DES, a major emphasis has been on how to achieve faster, or more complete, endothelial cell migration onto stent struts."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventor's summary information for this patent application: "Various embodiments of the present invention include a method of making a stent comprising: providing a stent including a bioresorbable polymer scaffold and a bioresorbable polymer coating over at least a portion of the scaffold; disposing the stent over a tubular mandrel such that a lumenal surface of the stent faces a surface of the mandrel, wherein the surface of the mandrel has a plurality of grooves aligned longitudinally; and radially compressing the stent over the surface of the mandrel such that the grooves at the surface of the mandrel form grooves on the lumenal surface of the stent, wherein the grooves on the luminal surface are aligned along a cylindrical axis of the stent.

"Further embodiments of the present include a method of making a stent comprising: providing a bioresorbable polymer tube having an original diameter; disposing the tube over a tubular mandrel such that a lumenal surface of the tube faces a surface of the mandrel, wherein the surface of the mandrel has a plurality of grooves aligned longitudinally; radially compressing the tube over the surface of the mandrel such that the grooves at the surface of the mandrel form grooves on the lumenal surface of the tube; and forming a stent scaffold from the tube after forming the grooves, wherein the lumenal surface of the stent scaffold includes grooves formed from the radial compression that are aligned along a cylindrical axis of the stent scaffold.

"Additional embodiments of the present invention include a method of making a stent comprising: conveying a melted polymer from an extruder barrel through an annulus of an annular die to form a tube, wherein the annular die has a first surface which forms an outer surface of the tube and an second surface that forms an inner surface of the tube, wherein the second surface of the annular die has grooves aligned longitudinally; allowing the grooves on the second surface of the annular die to form grooves in the inner surface of the tube formed as the polymer passes through the annular die; radially expanding the tube to an expanded diameter, wherein the radial expansion modifies a size of the grooves; and fabricating a stent scaffold from the tube with the expanded diameter, wherein a lumenal surface of the stent scaffold has the modified grooves that are aligned longitudinally.

"Other embodiments of the present invention include a method of making a stent comprising: providing a stent having a metallic scaffold and a polymer coating over the scaffold; disposing the stent over a tubular mandrel such that a lumenal surface of the stent faces a surface of the mandrel, wherein the surface of the mandrel has a plurality of grooves aligned longitudinally; and radially compressing the stent over the surface of the mandrel such that the grooves at the surface of the mandrel form grooves on the coating over the lumenal surface of the stent.

"Further embodiments of the present invention include a method of making a stent comprising: providing a stent having a metallic scaffold; disposing the stent over a tubular mandrel such that a lumenal surface of the scaffold faces a surface of the mandrel, wherein the surface of the mandrel has a plurality of grooves aligned longitudinally; and radially compressing the stent over the surface of the mandrel such that the grooves at the surface of the mandrel form grooves on the lumenal surface of the metal of the scaffold.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 depicts a stent.

"FIG. 2 depicts a portion of a grooved surface to illustrate its features.

"FIG. 3A depicts a grooved surface with rectangular grooves.

"FIG. 3B depicts a grooved surface with triangular grooves.

"FIG. 3C depicts a grooved surface with semicircular grooves.

"FIG. 4 depicts a radial cross-section of a scaffold 160 with grooves in the lumenal surface.

"FIG. 5 depicts a schematic illustration of a mandrel with grooves in its surface aligned longitudinally or parallel along its cylindrical axis.

"FIG. 6A depicts a radial cross-section of struts of a stent disposed over a mandrel with grooves on its surface that are aligned longitudinally.

"FIG. 6B depicts the stent and mandrel of FIG. 6A disposed within the aperture of a sliding wedge crimper.

"FIG. 6C illustrates the stent of FIG. 6B as shown by struts after the crimping procedure showing the grooves formed in the lumenal surface.

"FIG. 7A depicts the radial cross-section of a polymer tube disposed over a mandrel with grooves on its surface that are aligned longitudinally.

"FIG. 7B illustrates the tube and mandrel of FIG. 7A disposed within the aperture of a sliding wedge crimper.

"FIG. 7C illustrates the tube of FIG. 7B after the crimping procedure showing the grooves formed in the lumenal surface.

"FIG. 8A depicts a cross-section of a surface section that has grooves.

"FIG. 8B depicts the surface section of FIG. 8A with a planarizing coating that fills in grooves and planarizes the surface.

"FIG. 8C depicts the surface section of FIG. 8A with a conformal coating.

"FIG. 9A shows a radial cross-section of a conventional extrusion die.

"FIG. 9B shows a radial cross-section of an extrusion die of the present invention.

"FIG. 10 depicts a section of a tube wall before and after radial expansion."

For more information, see this patent application: Pacetti, Stephen D. Methods of Manufacture of Bioresorbable and Durable Stents with Grooved Lumenal Surfaces for Enhanced Re-Endothelialization. Filed January 17, 2014 and posted May 22, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=2981&p=60&f=G&l=50&d=PG01&S1=20140515.PD.&OS=PD/20140515&RS=PD/20140515

Keywords for this news article include: Surgery, Therapy, Angiology, Cardiology, Hematology, Restenosis, Thrombosis, Angioplasty, Blood Vessels, Cardio Device, Heart Disease, Catheterization, Medical Devices, Endothelial Cells, Surgical Technology, Vascular Surgical Procedures, Abbott Cardiovascular Systems Inc..

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Source: Politics & Government Week


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