News Column

Patent Issued for Implantable Medical Devices

August 4, 2014



By a News Reporter-Staff News Editor at Biotech Business Week -- Boston Scientific Scimed, Inc. (Maple Grove, MN) has been issued patent number 8784465, according to news reporting originating out of Alexandria, Virginia, by NewsRx editors (see also Boston Scientific Scimed, Inc.).

The patent's inventors are Sahatjian, Ronald A. (Lexington, MA); Tan, Francisca (Boston, MA); Mather, Patrick T. (Chagrin Falls, OH); Liu, Changdeng (Storrs, CT); Campo, Cheryl J. (Cleveland Heights, OH).

This patent was filed on November 5, 2010 and was published online on July 22, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The body includes various passageways such as arteries, other blood vessels, and other body lumens. These passageways sometimes become occluded or weakened. For example, the passageways can be occluded by a tumor, restricted by plaque, or weakened by an aneurysm. When this occurs, the passageway can be reopened or reinforced, or even replaced, with a medical endoprosthesis. An endoprosthesis is typically a tubular member that is placed in a lumen in the body. Examples of endoprosthesis include stents and covered stents, sometimes called 'stent-grafts'.

"An endoprosthesis can be delivered inside the body by a catheter that supports the endoprosthesis in a compacted or reduced-size form as the endoprosthesis is transported to a desired site. Upon reaching the site, the endoprosthesis is expanded, for example, so that it can contact the walls of the lumen.

"Prostate enlargement, also known as benign prostate hyperplasia or benign prostate hypertrophy, is a common affliction among older men. The condition involves swelling of the prostate. The prostate surrounds the urethra, or urinary tract, and enlargement of the prostate may restrict passage of urine from the bladder towards the urethra. Benign prostate hyperplasia is uncomfortable because it makes urination difficult or impossible. The condition is also dangerous because it can lead to infection of the bladder and kidneys.

"Prostate enlargement can be treated with surgery known as resection. Resection can be accomplished by cutting away a large portion of the prostate gland. Prostate enlargement can also be treated with heat treatment, cold treatment, or ablation.

"Sometimes a restricted urethra can be treated with a prostatic stent to support the urethra and keep it open despite pressure from the enlarged prostate. A prostatic stent may be implanted permanently or as an interim solution."

Supplementing the background information on this patent, NewsRx reporters also obtained the inventors' summary information for this patent: "The invention relates to implantable medical devices, for example, a stent including a polymer.

"In one aspect, the invention features a medical device. The medical device includes a balloon catheter having an expandable member, e.g., an inflatable balloon, at its distal end and a stent or other endoprosthesis. The stent is an apertured tubular member formed of a polymer and is assembled about the balloon. The stent has an initial diameter for delivery into the body and can be expanded to a larger diameter by inflating the balloon. The polymer does not flow substantially during expansion and substantial stress relaxation or creep does not occur so that the geometry of the stent is maintained.

"In another aspect, a tubular endoprosthesis including a polymer body is provided and delivered into a body lumen. The endoprosthesis is expanded in the body lumen under conditions of expanding pressure and temperature so that the wall thickness of the polymer body is substantially maintained.

"In another aspect, a polymer tube is formed to a first, large diameter. An aperture pattern is cut into the tube wall. The polymer is crosslinked or crystallized. The polymer tube is deformed to a second, small diameter. The polymer tube is expanded in a body lumen to a diameter larger than the second diameter by application of pressure and heat.

"In another aspect, a polymer tube is formed to a first, small diameter. An aperture pattern is provided in the tube wall. The polymer is crystallized or crosslinked. The tube is expanded in a body lumen by application of pressure and heat.

"In another aspect, an implantable medical apparatus includes an element operable for movement within the body by mechanical force applied to the element. The element includes a polymer having a melt or glass transition temperature in the range above body temperature to about 50.degree. C. or 60.degree. C. and exhibiting a plateau in a plot of storage modulus as a function of temperature at melt or glass transition. In embodiments, the element is a stent. The stent may be generally a tubular body that includes an apertured wall. The stent may be operable for expansion from a first, smaller diameter to a second larger diameter for implantation in a lumen. The thickness of the stent wall varies by about 1% or less between the first and second diameter.

"In another aspect, the invention features a medical device including a polymer having a melt or glass transition temperature above body temperature and exhibiting an approximate plateau in a plot of storage modulus as a function of temperature at melt or glass transition. The melt or glass transition temperature may be, for example, above about 37.degree. C. The medical device may undergo a triggerable event at about the plateau. The triggerable event may be, for example, a change in the flexibility, a change in the porosity, a change in the coefficient of friction or a change in the surface roughness. The medical device may be, for example, a stent that has a portion that has a collapsed position that can be reverted to an expanded position by a trigger subsequent to insertion into the body.

"Aspects may include one or more of the following features. The polymer body, optionally, includes apertures. The polymer body has a ratio of aperture open area to wall area of about 0.5 or more or 0.7 or more. The endoprosthesis is expanded by simultaneously applying an expanding pressure and heat to the endoprosthesis. The polymer body is heated above the melt or glass transition temperature of polymer in the polymer body. The polymer body is elastomeric at the melt or glass transition temperature. The polymer is elastomeric at body temperature. The polymer is crystalline. The polymer is crosslinked. The polymer is radiation crosslinked. The melt or glass transition temperature is about 40 to 50.degree. C. The melt or glass transition temperature has a transition range of about 5.degree. C. or less. The polymer exhibits a plateau in the melt or glass transition range in a plot of storage modulus as a function of temperature. The polymer body includes a drug, radiopaque agent or magnetic heating agent. The polymer is a shape memory polymer, e.g. capable of remembering a smaller diameter configuration after expansion. The polymer is, for example, polynorbornene, polycaprolactone, polyenes, nylons, polycyclooctene (PCO), blends of PCO and styrene-butadiene rubber, polyvinyl acetate/polyvinylidinefluoride (PVAc/PVDF), blends of PVAc/PVDF/poly-methylmethacrylate (PMMA), polyurethanes, styrene-butadiene copolymers, polyethylene, trans-isoprene, blends of polycaprolactone and n-butylacrylate, PVC, e.g., plasticized PVC, and blends thereof. An expansion pressure of about 1 atm or more is applied. The endoprosthesis is delivered on a catheter. The endoprosthesis is delivered to a site of occlusion and the site is simultaneously dilated while expanding the endoprosthesis. The endoprosthesis is delivered to a site of lumen curvature and the endoprosthesis is expanded at the site. The endoprosthesis is delivered to a vascular lumen. The endoprosthesis is delivered adjacent (into) the prostate.

"Aspects may include one or more of the following. A heat applicator applies heat to the stent during inflation of the balloon to expand the balloon to the expanded diameter. The polymer has a melt or glass transition temperature in the range of about 40 to 50.degree. C. and a modulus at the melt or glass transition temperature sufficient to maintain the stent geometry or under application of pressure and/or heat. The polymer exhibits a plateau in the storage modulus in the range of melt or glass transition temperatures. The stent has a wall thickness of about 0.005 to 5 mm. The stent has an initial unexpanded inner diameter in the range of about 1 mm to 5 mm. The stent has an expanded inner diameter of about 1 mm to 20 mm. The stent may be expandable to about 100% or 400% or more of the initial inner diameter. An example of a coronary stent has an initial inner diameter of about 2 mm, and expanded inner diameter of about 4 mm and the wall thickness is about 0.005 mm to 0.1 mm. The stent can be in the form of a tube including aperture areas provided in the tube. The aperture are in the shape of elongate slots, e.g., when the stent is in the small diameter condition. The apertures have a dimension of about 1 mm or less in the small diameter condition. The apertures are in the shape of diamond-like openings, e.g. when the stent is in an expanded condition. The stent can be a wire-form formed of one or more filaments configured to generally define a tube.

"Embodiments may include one or more of the following advantages. A balloon expandable stent made of a polymer can be provided that maintains the integrity of the stent geometry on expansion and heating. Maintenance of stent geometry is desirable since geometry affects, for example, the resistance to compression in the body and a predictable geometry is important to avoid irregular surfaces, kinking, or extensions of material into the body lumen which can interfere with the flow of body fluid. The polymers can be elastomers that have melting or glass transitions at temperatures safe for use in the body and exhibit elastomeric properties at both the melted or glass transition stage and the solid or crystalline phase. The stent body exhibits high resistance to inward compressive forces when the polymer is in the solid or crystalline phase. The elastomeric nature of the polymer in the melted or glass state enhances the ability to maintain geometry as the stent is expanded. For example, the polymer exhibits minimal flow during expansion and the thickness of the stent remains substantially constant. Elastomeric properties in the crystalline or solid state enhance the ability to conform to torturous curvature in narrow body lumens. High compression resistance allows the stent to maintain the body lumen open and resist occluding forces such as elastic recoil or the growth of thrombus from the vessel wall.

"In another aspect, the invention features a polymeric stent having a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen. The stent may be in the form, for example, of a coiled elongated element (for example, a strand, a tape or a flattened tube). The stent may be further heated to a second temperature that is higher than the first temperature and removed as a substantially uncoiled element. When the stent is in the form, for example, of a coiled elongated flattened tube, the flattened tube may include a central opening that includes a medicament that can be released by the inserted stent. In some implementations, the medicament is compounded into the plastic or is a coating on the plastic. In some implementations, the portion is at an end of the stent and the portion is flared or stepped. In other implementations, the portion includes less than 50% of the length of the stent.

"In another aspect, the invention features a polymeric stent in the form of a coiled elongated element, and having a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen. When the stent is heated to a second temperature higher than the first temperature, the modulus of the element lowers sufficiently that the stent can be removed from the cavity or lumen as a substantially uncoiled element.

"In yet another aspect, the invention features a method of treating a non-vascular cavity or lumen. The method includes inserting a polymeric stent having a portion in a collapsed position that can be reverted, by heating, to an expanded position. Following insertion, the stent is heated sufficiently to revert the portion in the collapsed position to the expanded position. The method may further include heating the stent having the portion in the expanded position sufficiently to soften the stent, and removing the softened stent from the cavity or lumen.

"The stent may be, for example, a coiled elongated element (for example, a rod, a tape or flattened tube) and the heating of the stent prior to removal allows the stent to be removed in a substantially uncoiled state. This method provides ease of removal, for example, for removing prostatic stents that have been inserted on an interim basis. The heating may be performed, for example, on a delivery tube.

"In some embodiments, the portion of the stent is at the end of the stent and may be flared when in the expanded position. In other embodiments, for example, the portion of the stent is not at an end of the stent.

"In still another aspect, the invention features a polymeric stent including metal particles. A portion of the stent has a collapsed position that can be reverted to an expanded position by heating. The heating may be performed using inductive heating to revert the portion in the collapsed position to the expanded position.

"In another aspect, the invention features a stent having an exterior surface that includes a plurality of protruding elements that extend outwardly from the surface. The protruding elements may be useful in helping the stent retain its position, for example, after insertion into the prostatic urethra.

"In some embodiments, the protruding elements are formed of monofilament. The monofilament may include a plurality of constrictions along its length.

"In some implementations, the stent is a polymeric stent and the stent has a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen.

"In another aspect, the invention features an implantable endoprothesis including a tubular member that includes a polymeric material. The tubular member has a wall having a first transverse dimension and a first longitudinal length, measured when at the first transverse dimension, sized for delivery into a lumen. Upon exposure to an elevated temperature, the tubular member can be expanded to a second transverse dimension that is at least about fifty percent larger than the first transverse dimension within the lumen, the first and second transverse dimensions being measured from an outer surface of the wall of the tubular member. The tubular member also has a second longitudinal length, measured when at the second transverse dimension. After expansion from the first transverse dimension to the second transverse dimension, the second longitudinal length decreases by less than about fifty percent, measured relative to the first longitudinal length.

"In some implementations, the tubular member has a wall thickness, measured from an inner surface of the wall to the outer surface of the wall, and the wall thickness decreases by greater than about twenty percent, e.g., greater than about thirty percent, greater than about fifty percent, greater than about seventy-five percent, or greater than eighty-five percent, after expansion from the first transverse dimension to the second transverse dimension.

"In some embodiments, after expansion from the first transverse dimension to the second transverse dimension that is at least about forty percent larger than the first transverse dimension, e.g., seventy-five percent larger than the first transverse dimension, the second longitudinal length decreases by less than about twenty percent, measured relative to the first longitudinal length.

"The tubular member can be, for example, approximately circular in transverse cross-section, or the tubular member can have other transverse shapes, e.g., non-circular, e.g., elliptical.

"In some embodiments, the polymeric material has a softening temperature from about 40.degree. C. to about 60.degree. C., e.g., 45, 50, 55, or 58.degree. C. The polymeric material can be cross-linked, non-cross-linked, a shape memory polymer, or a non-shape memory polymer. In some instances, the polymeric material is, for example, polycyclooctene (PCO), a styrenic elastomer, a styrenic block copolymer, a styrene-butadiene rubber, a polyolefin, trans-isoprene, or blends of these materials. The polymeric material can include a filler, e.g., a radio-opaque agent, e.g., bismuth carbonate, barium sulfate, or mixtures of these materials. Other fillers includes, for example, a thermal conductor, e.g., a boron nitride, other ceramics, or a metal.

"In some implementations, the tubular member is, for example, substantially straight before it is expanded. In specific embodiments, the tubular member is curved after it is expanded and/or the outer surface of the wall of the tubular member includes a protruding element that extends outwardly from the outer surface after the tubular member is expanded.

"In some embodiments, the wall of the tubular member includes at least one aperture defined therein.

"In some implementations, the plastic has a elastic modulus of greater than about 50,000 psi, e.g., greater than about 75,000, greater than about 150,000, greater than about 250,000, or greater than about 500,000 psi.

"In another aspect, the invention features a method of treating a patient. The method includes placing the endoprosthesis just discussed on a delivery system. The delivery system then is used to deliver the endoprosthesis a lumen, e.g., a pulmonary lumen, an esophageal lumen, a biliary lumen, an enteral lumen, a ureteral lumen, and a urethral lumen. The endoprosthesis then is heated and expanded within the lumen. In a specific implementation, the delivery system includes a balloon catheter.

"The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, and advantages of the invention will be apparent from the description and drawings and from the claims."

For the URL and additional information on this patent, see: Sahatjian, Ronald A.; Tan, Francisca; Mather, Patrick T.; Liu, Changdeng; Campo, Cheryl J.. Implantable Medical Devices. U.S. Patent Number 8784465, filed November 5, 2010, and published online on July 22, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8784465.PN.&OS=PN/8784465RS=PN/8784465

Keywords for this news article include: Angiology, Endoprosthesis, Biotechnology Companies, Boston Scientific Scimed Inc..

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


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Biotech Business Week


Story Tools






HispanicBusiness.com Facebook Linkedin Twitter RSS Feed Email Alerts & Newsletters