United States Patent [191
`Pathak et a1.
`
`[54]
`
`[75]
`
`[73]
`
`[21]
`[22]
`
`[63]
`
`[51]
`
`[53]
`
`[5 6]
`
`POLYMERIC ARTICLE FOR
`INTRALUMINAL
`PHOTOTHERMOFORMING
`
`Inventors: Chandrashekhar P. Pathak, Waltham;
`Amarpreet S. Sawhney, Newton;
`Jelfrey A. Hubbell, Concord; Stephen
`J. Herman, Andover, all of Mass;
`Laurence A. Roth, Windham, N.H.;
`Patrick K. Campbell. Georgetown;
`Kevin M. Berrigan, Woburn, both of
`Mass; Peter K. Jarrett, Southbury,
`Conn.; Arthur J. Coury, Boston, Mass.
`
`Assignee: Focal, Inc., Lexington, Mass.
`
`Appl. No.: 477,370
`Filed:
`Jun. 7, 1995
`
`Related US. Application Data
`
`Continuation of PCl'IUS94/O4824, Apr. 23, 1994 which is a
`continuation-impart of Ser. No. 54,385, Apr. 28, 1993,
`abandoned.
`
`Int. (11.6 ...................................................... .. A61F 2/06
`
`US. Cl. . . . . . . . . . . . . . .
`
`Field of Search
`.
`
`. . . . . . . .. 623/1; 623/12
`
`623/1, 12; 606/194.
`606/195
`
`References Cited
`
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`3,915,824
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`
`US005741323A
`Patent Number:
`Date of Patent:
`
`[11]
`
`[45]
`
`5,741,323
`Apr. 21, 1998
`
`OTHER PUBLICATIONS
`
`Poppas, D.P. et al., “Chromophore Enhanced Laser Welding
`of Canine Ureters in Vitro Using A Human Protein Solder:
`A Preliminary Step for Laparoscopic Tissue Welding”, The
`Journal of Urology, vol. 150. pp. 1052-1055, Sep., 1993.
`Choma, T.J., MD. et al., “CO2 Laser Urethroplasty in the
`Rabbit: A Preclinical Model”, Lasers in Surgery and Medi
`cine, vol. 12, pp. 639-644, 1992.
`Klioze, S.D. et al., “Development and Initial Application of
`a Real Time ‘Thermal Control System for Laser Tissue
`Welding”, The Journal of Urology, vol. 152, pp. 744-748,
`Aug., 1994.
`Poppas, D.P. et al., “Laser Welding in Urethral Surgery:
`Improved Results with a Protein Solder”, The Journal of
`Urology, vol. 139. Feb., 1988, pp. 415-417.
`Poppas, D.P. et al., “Patch Graft Urethroplasty Using Dye
`Enhanced Laser Tissue Welding with a Human Protein
`Solder: A Preclinical Canine Model”. The Journal of Urol
`ogy, vol. 150, pp. 648-650, Aug. 1993.
`
`(List continued on next page.)
`
`Primary Examiner—Michael J. Milano
`Attorney, Agent, or Firm-Wolf, Green?eld & Sacks, RC.
`[57]
`ABSTRACT
`
`A method and apparatus for molding polymeric structures in
`vivo is disclosed. The structures comprise polymers that
`may be heated to their molding temperature by absorption of
`visible or near-visible wavelengths of light. By providing a
`light source that produces radiation of the Wavelength
`absorbed by the polymeric material, the material may be
`selectively heated and shaped in vivo without a correspond
`ing heating of adjacent tissues or ?uids to unacceptable
`levels. The apparatus comprises a catheter having a shaping
`element positioned near its distal end. An emitter provided
`with light from at least one optical ?ber is positioned within
`the shaping element. The emitter serves to provide a mold
`able polymeric article positioned on the shaping element
`with a substantially uniform light ?eld, thereby allowing the
`article to be heated and molded at a desired treatment site in
`a body lumen.
`
`24 Claims, 7 Drawing Sheets
`
`LIGHT SOURCE!
`CONTROLLER
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page1
`
`

`

`5,741,323
`Page 2
`
`US. PATENT DOCUMENTS
`
`9/1981 Pom-
`4,286,536
`4/1984 Borysko-
`4,444,927
`5/1984 Hussein et a1. .
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`3/1986 Johnson-
`4,575,373
`6/1987 Moore et a1. .
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`4,702,917 10/1987 Schindler.
`4,750,910
`6/1988 Takayanagi 61 a1. .
`4,754,752
`7/1988 Ginsburg et a1. .
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`1/1989 SPe‘ars-
`4,801,477
`1/1989 Fudlm-
`4,846,165
`7/1989 Hare et a1. .
`4,878,492 11/1989 Sinofsky .
`‘
`4,892,098
`1/1990 Sauer.
`4902290 2/1990 Fleckenstein ----------------------------- -- 623/1
`4,955,377
`9/1990 Leanox ela1~
`5,009,655
`4/1991 Dalg?ault-
`5,053,033 10/1991 Clarke-
`5,059,211 10/1991 Stack ela1~
`5,066,231 11/1991 Oxman.
`5,085,629
`2/1992 Goldberg.
`5 992841 3/1992 SP6“ '
`5,100,429
`3/1992 Smofsky.
`5 126 141
`6,1992 Henry _
`5,139,480
`8/1992 Hickle 6141..
`5,145,945
`9/1992 Tang _
`5,147,385
`9/1992 Beck .
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`
`5,156,620 10/1992 Pigott.
`5,163,952 11/1992 Froix.
`5,178,618
`1/1993 Kandarpa.
`5,185,408
`2/1993 Tang.
`5,196,005
`3/1993 Doimn _
`5,197,978
`3/1993 Hess ........................................ .. 623/12
`5,199,951
`411993 Spears _
`5 209,776 5/1993 Bass ‘
`5,213,115
`5/1993 zytkovicz _
`5 ,213 ,530 5/1993 slepian ‘
`5,226,430 7/1993 Spears.
`5,242,451
`9/1993 Harada .................................... .. 623/12
`5,292,362 3/1994 Bass .
`5,300,020 4/1994 L’Espemnce ,
`5,312,395 5/1994 Tan_
`5,330,782
`7/1994 Kanazawa ................................. .. 623/1
`5,334,191
`8/1994 Poppas et 41..
`5,334,201
`8/1994 Cowan.
`5,500,013
`3/1996 Buscemi .................................... .. 623/1
`5,512,291
`4/1996 Li .............................................. .. 623/1
`
`OTHER PUBLICATIONS
`Poppas, DJ’. et al., “Preparation of Human Albumin Solder
`.
`.
`,,
`.
`.
`.
`for Laser T1ssue Weldmg , Lasers 1n Surgery and Medwme.
`vol- 13, pp. 577-580. 1993.
`_
`‘
`Mehmet et al., "I‘1ssue Soldenng by use of Indocyamne
`Green Dye-Enhanced Fibrinogen With the Near Infrared
`Diode Laser”, J. Vascular Surgery, 11:5 (May, 1990).
`
`1
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page2
`
`

`

`US. Patent
`
`Apr. 21, 1998
`
`Sheet 1 0f 7
`
`5,741,323
`
`.. Pk:
`
`I
`
`NE._._ONCZOU
`
`
`
`\wUQDOm BIO:
`
`/ v
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page3
`
`

`

`US. Patent
`
`Apr. 21, 1998
`
`Sheet 2 0f 7
`
`5,741,323
`
`mm
`
`mm
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page4
`
`

`

`U.S. Patent
`
`Apr. 21, 1998
`
`Sheet 3 0f 7
`
`40
`
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`
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`
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`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page5
`
`

`

`US. Patent
`
`Apr. 21, 1998
`
`Sheet 4 0f 7
`
`5,741,323
`
`wm
`
`/ . 4i
`
`mm/
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page6
`
`

`

`US. Patent
`
`Apr. 21, 1998
`
`Sheet 5 of 7
`
`5,741,323
`
`R35
`
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`
`//83
`///
`
`87
`
`Fig. 5A
`
`Fig.5B
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page7
`
`

`

`US. Patent
`
`Apr. 21, 1998
`
`Sheet 6 of 7
`
`5,741,323
`
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`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page8
`
`

`

`US. Patent
`
`Apr. 21, 1998
`
`Sheet 7 of 7
`
`I 5,741,323
`
`H6
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`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page9
`
`

`

`5,741,323
`
`1
`POLYMERIC ARTICLE FOR
`IN TRALUMINAL
`PHOTOTHERMOFORMING
`
`2
`surrounding body tissues and ?uids. The result is that
`undesired amounts of heat are transferred into the surround
`ing body tissues and ?uids.
`Accordingly, a need exists for apparatus for implanting
`polymeric materials in vivo that avoids the problems asso
`ciated with the prior art. A need also exists for methods for
`delivering and reshaping materials in vivo which allow a
`physician to safely and easily introduce the material into a
`patient, con?gure the material as desired. and deposit the
`material at a desired location for at least a therapeutically
`desirable period of time. A further need exists for materials
`and methods for reshaping such materials in vivo that offer
`the ability to reshape the materials while minimizing the
`amount of energy that is transferred to surrounding tissues
`and physiological ?uids.
`
`10
`
`15
`
`‘This application is a continuation of international appli
`cation Ser. No. PCP/11894104824, ?led Apr. 23, 1994.
`entitled APPARATUS AND METHODS FOR INTRALU
`MINAL PHOTOTHERMOFORMING, designating the
`US. which entered National Phase in the US. concurrently,
`which is a continuation-in-part of U.S. Ser. No. 08/054385,
`?led April 28, 1993, entitled PHOTOI‘HERMOFORMING
`OF THERAPEUTIC MATERIALS, abandoned.
`
`FIELD OF THE INVENTION
`This invention pertains to devices for intraluminal
`implantation of polymeric materials in a human or animal
`patient and methods for delivering such materials.
`
`SUMMARY OF THE INVENTION
`The present invention pertains to apparatus and methods
`for the delivery of polymeric material in vivo, and more
`particularly to the implantation of polymeric material into
`tissue lumens of human or animal patients. More particu
`larly the invention relates to methods for photothermoforrn
`ing a polymeric article in vivo, that is, modifying the shape
`of a polymeric article in vivo by using light to selectively
`heat the article to a temperature at which it is ?uent. molding
`the article into a desired conformation, and allowing the
`article to become non-?uent in the desired conformation.
`Material from which the article is made is selected such that
`it is moldable at a temperature at which substantial damage
`to adjacent or proximate tissue does not occur.
`Heating is achieved by irradiating, or illuminating the
`article with light of a wavelength or within a wavelength
`range at which the polymeric material readily absorbs. or at
`which adjacent tissue or body ?uids do not signi?cantly
`absorb. According to one aspect of the invention, the article
`is irradiated at a wavelength or within a wavelength range at
`which the polymeric material readily absorbs and at which
`adjacent tissue or ?uids do not signi?cantly absorb. This is
`achieved by providing polymeric material that relatively
`strongly absorbs the radiation provided, or by loading the
`polymeric material with a chromophore that readily absorbs
`the radiation. It is preferred that the light used to thermoform
`the polymer be of a wavelength that is not readily absorbed
`by body tissues or ?uids, thereby minimizing the amount of
`light absorbed by, and heat generated in, the tissue or ?uid
`in the region of the therrnoforming. According to one aspect
`of the invention visible or near-infrared light is provided
`locally to the polymeric material by an optical tip assembly
`on a delivery device.
`The resulting shaped article provides a therapeutic bene?t
`by acting. in one embodiment, as a stent to maintain patency
`through a blood vessel. Numerous other therapeutic shapes
`are contemplated as well.
`According to one embodiment. the polymeric material has
`a chromophore such as a dye or pigment compounded
`therein. The chromophore is selected. in conjunction with a
`particular light source. to absorb light that is produced by the
`light source. The absorbed light is converted to thermal
`energy which acts to heat the polymer. According to one
`aspect of the invention. the chromophore is thermochromic.
`As an alternative to compounding the polymer with a
`chromophore. polymers that naturally absorb the wave
`length spectrum of the light produced by the source may be
`used. The natural absorption spectrum of the material may
`result from the polymer in its native state. or alternatively. by
`the incorporation of one or more chromophores into the
`
`20
`
`25
`
`35
`
`BACKGROUND OF THE INVENTION
`‘The application of polymeric materials to body tissues of
`human or animal patients is becoming increasingly impor
`tant in medicine. Among the proposed uses of such materials
`are the alteration of tissue; the creation or preservation of
`lumens. channels or reservoirs for the passage or collection
`of ?uids; the creation of matrices for the growth of tissue;
`the control of undesirable tissue growth; the delivery of
`therapeutic agents to a tissue surface; the ability to join a
`tissue surface to another tissue or an arti?cial implant; the
`ability to isolate or protect tissue or lesions to enable or
`mediate healing; and the ability to mediate the rate of
`substances or energy passing into. out of, or through tissue.
`Although it has been recognized that the use of polymeric
`materials in vivo may offer signi?cant therapeutic e?ects. to
`date such applications have met many limitations. For
`example. the methods for applying such polymers to tissue
`surfaces often require the use of pressure, heat or electrical
`energy exceeding limits of tolerability at the tissue site.
`Likewise various chemical effects associated with such
`polymers have been found to be physiologically unaccept
`able.
`Numerous methods for reshaping polymeric materials in
`vivo are known in the prior art. In particular, US. Pat. No.
`5.213.580 and international Publication WO 90/01969. both
`to Slepian et al.. the entire disclosures of which are incor
`porated herein by reference, describe methods in which
`polymers having melting points slightly above physiological
`temperatures are implanted into a patient and in which such
`polymers are melted via contact with heated ?uids and
`shaped using mechanical force provided by a balloon cath
`eter. Unfortunately, many of the methods known in the art
`su?er from the need to use energy levels beyond those which
`are physiologically tolerable. or from the inability to su?i
`ciently control the shape change and/or temperature of the
`polymeric material.
`Typically, the primary limitation in prior art methods for
`the delivery of energy to an implanted device is the inability
`to direct the energy speci?cally to the device, while mini—
`mizing energy delivery to body tissue. For example, it is
`known in the prior art that polymeric devices such as stents
`may be delivered to speci?c locations in vivo using a balloon
`catheter. Such stents may be heated at the site by ?lling the
`balloon with a heated ?uid. In that method, heat is conducted
`from the ?uid in the balloon. through the balloon material.
`and into the stent. Since conduction is a relatively slow
`process and the balloon has a relative large thermal mass,
`energy is transferred not only to the stent, but also to the
`
`40
`
`45
`
`55
`
`65
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page10
`
`

`

`5,741,323
`
`4
`can be achieved using a light source which produces a
`wavelength spectrum that is not readily absorbed by body
`tissue. Light from the source is used to heat a polymeric
`material that is at least partially absorptive of the light in the
`spectral range. Even if only a portion of the light (e.g., 50%)
`is absorbed by the polymer. transmitted light will not be
`readily absorbed by the surrounding tissue and will have a
`minimal heating e?°ect on that tissue. In this case, light
`which is not absorbed by the polymer is absorbed by a
`relatively large area of tissue as it penetrates beyond the
`polymer. As such, resultant heating occurs throughout a
`much larger volume of tissue. Since the temperature rise in
`the tissue is a function of energy absorbed within a unit
`volume of tissue. localized heating is signi?cantly lower as
`compared to the heating caused by wavelengths that are
`readily absorbed. i.e., by a smaller volume of tissue. The
`requirement for wavelengths which have low tissue absorp
`tion characteristics is necessary only to the extent that excess
`heating of the tissue does not occur or is undesirable at the
`particular treatment location.
`Alternatively, it is possible to use light having a spectrum
`that is absorbed by body tissues and ?uids provided that the
`polymeric material is highly absorptive of light in the
`spectral range. In this case. the polymer will absorb sub
`stantially all of the light. thereby minimizing the amount that
`is transferred to the body tissue and minimizing the heating
`effect of that light on tissue.
`The polymeric materials of the present invention must
`satisfy various criteria. including molding temperature.
`crystallinity, absorption characteristics. bioerodability,
`physical strength, biocompatibility and light transmission
`and absorption characteristics. Each of these are discussed
`below.
`
`3
`polymeric backbone or side-chains. In each case. however,
`it is necessary that the polymer satis?es other selection
`criteria such as biocompatibility and moldability.
`By selecting a chromophore. or polymeric material, hav
`ing maximum absorption characteristics at or near a par
`ticular wavelength or spectral range, in conjunction with a
`light source that emits at or near the particular wavelength
`or spectral range. the polymer is provided with the ability to
`be efficiently heated via light absorption. In this way. selec
`tive heating of the polymer with minimal heating of sur
`rounding body tissues and ?uids may be achieved.
`Broadly, the apparatus comprises a catheter having a
`shaping element positioned near its distal end. The poly
`meric material is positioned adjacent or near the shaping
`element, illuminated by light delivered by the catheter and
`thus heated to render it ?uent. and molded by the shaping
`element into contact with a tissue lumen.
`In one embodiment. the apparatus comprises a balloon
`dilatation catheter having an associated optical tip assembly.
`The polymeric material is positioned on the balloon, pref
`erably in the form of a tube or sleeve which surrounds the
`balloon. The optical tip assembly serves to direct light to the
`polymeric material. The light may be provided from an
`external source. Upon absorption of the light, the polymeric
`material is heated to a temperature at which it becomes
`moldable. In?ation of the balloon causes the moldable
`polymeric material to expand outwardly. thereby pressing
`the polymer into contact with the tissue lumen.
`Alternatively, in cases in which The polymeric material can
`be recon?gured prior to molding (i.e., the polymeric mate
`rial comprises a rolled sheet or a tube having axial pleats),
`the material is recon?gured using the balloon and then
`heated to mold it into conformance with an adjacent tissue
`surface.
`According to .another embodiment. the apparatus further
`includes a retractable sheath which is designed to encapsu
`late the polymeric material on the balloon as the material is
`guided to a treatment location in vivo. Once positioned. the
`sheath is retracted to expose the material and to allow the
`material to be heated and molded as described above. The
`sheath may include a tapered distal tip, formed of a ?exible
`polymer. which expands radially over the balloon and poly
`meric material as the sheath is withdrawn over those struc
`tures. As an alternative, the tip may include at least one
`longitudinal slit which allows radial expansion of the tip.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 illustrates one embodiment of a laser balloon
`catheter suitable for delivery of a polymeric material;
`FIGS. 2a and 2b illustrate one embodiment of a laser
`balloon catheter suitable for delivery of a polymeric mate
`rial;
`FIG. 3 is an illustration of a laser balloon catheter
`showing two embodiments of an optical emitter;
`FIGS. 4a and 4b illustrate a second embodiment of a laser
`balloon catheter suitable for delivery of a polymeric mate
`rial;
`FIGS. 5a and 5b illustrate a retractable sheath suitable for
`use with the laser balloon catheters of FIGS. 1. 2 and 4;
`FIGS. 6a and 6b are schematic illustrations of another
`embodiment of a device for providing a thick polymeric ?lm
`on a luminal wall; and
`FIGS. 7a and 7b are schematic representations of an
`optical emitter catheter for use with the device of FIG. 6b.
`DETAILED DESCRIPT ION OF THE
`INVENTION
`The ability to selectively heat an implanted polymeric
`material using light in the visible or near-visible spectrum
`
`25
`
`35
`
`45
`
`Molding Temperature
`The material must become either moldable or molten at a
`temperature that is not signi?cantly injurious to tissue or ‘
`surrounding physiological ?uids if maintained at that tem
`perature for the amount of time required to implant and
`shape the material. Additionally, the material must become
`moldable at a temperature above about 40 degrees C. That
`temperature has been selected as being a temperature that is
`greater than body temperatures associated with hyperther
`mia or fever (approximately 38-40 degrees C.). The require
`ment of the minimum molding temperature is to prevent the
`material from spontaneously softening or melting in
`response to elevated. physiologically occurring body tem
`peratures.
`As used herein. the term “molding temperature” is used to
`describe a minimum melting temperature, Tm. or a glass
`transition temperature, T8. at which the polymer may be
`plastically deformed using physiologically acceptable
`forces. Likewise. the melting or glass transition temperature
`must be below that at which signi?cant mechanical or
`thermal damage to body tissues occurs. The term “thermo
`forming” is used no describe the process wherein a poly
`meric article is heated no at least its molding temperature
`and then reshaped by external or internal forces.
`Crystallinity and Physical Strength
`It is preferred that the material have a substantially
`crystalline or semi-crystalline structure so that when heated
`to its melting temperature. it will undergo a rapid transition
`to a viscous ?uid that will ?ow readily. yet remain cohesive.
`when subjected to molding forces associated with thermo
`forming. As an alternative. the material may be glassy or
`
`55
`
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`5,741,323
`
`6
`In some applications it is preferred that the material not
`completely cover, but only partially cover an area of tissue
`to be supported or otherwise addressed by the material. For
`example. the material may be applied to support a portion of
`a tissue lumen. rather than the entire lumen. The physical
`form may be varied to suit the ?nal application. While
`relatively thin solid ?lms or sheets are preferred for many
`applications. fenestrated or rnicroporous sheets may also be
`used. Spun webs, with or without melt-bonding or
`calendaring, may also be of use. The material can include
`prede?ned perforations or apertures once transformed from
`a delivery con?guration to its therapeutic con?guration. If
`the device is intended to be delivered in the form of a hollow
`cylinder. the cylinder may be provided with a plurality of
`perforations which open or remain open once the cylinder
`has been expanded to a larger, therapeutic con?guration. If
`the material is used as a support structure for an artery, the
`perforations may allow increased axial ?exibility to facili
`tate delivery and reduce tissue erosion during and after
`implementation, improved perfusion of side branch vessels
`by decreasing the likelihood of obstruction of such vessels.
`and increased ingrowth of tissue for anchoring and encap
`sulation of the material.
`
`Absorption Characteristics
`The polymeric material should preferably absorb light
`within a wavelength range that is not readily absorbed by
`tissue, blood elements. physiological ?uids, or water.
`Although wavelengths in The spectral range of about
`250-1300 nm may be used. wavelengths in the range of
`about 300-1000 nm are preferred, and wavelengths in the
`range of about 500-850 are especially preferred. In the case
`in which a chromophore such as a dye or pigment is
`incorporated into the polymeric material. the material itself
`must be su?iciently transparent to allow the light to reach
`and be absorbed by the dye or pigment.
`For both the bioerodable and non-bioerodable polymers,
`chromophores and light sources suitable for use in the
`invention may be selected from dye or pigment materials
`and lasers corresponding to those materials including, but
`not limited to. the following:
`
`15
`
`25
`
`30
`
`35
`
`5
`have a glassy component. In that case. if heated su?iciently
`above its glass transition temperature, the material will also
`?ow readily and remain cohesive when subjected to molding
`forces.
`The materials useful in the invention are termed “?uent”
`when in their moldable state. The actual viscosity of the
`?uent material that allows the material to be molded without
`signi?cant mechanical disruption of the tissue depends upon
`the particular tissue and the method by which the material is
`molded. In general. it is preferred that the material be such
`that, once heated to its molding temperature, (i.e.. rendered
`?uent), the material may be shaped or formed using a
`physiologically acceptable amount of force. Likewise, it is
`preferred that the molding temperature be low enough to
`prevent signi?cant thermal damage during the molding
`process. The ability to be molded using a minimum amount
`of force reduces the possibility of tissue injury potentially
`occurring as a result of misuse or structural failure of the
`polymeric material or the force-supplying component.
`Determination of an acceptable amount of force and
`thermal load depends upon at least a) the viscosity of the
`material in its moldable state, b) the length and/orthiclmess
`of the material, c) the geometric con?guration of the
`material, and d) the temperature at which the material
`becomes sufficiently ?uent. Additionally, forces and thermal
`loads that may be physiologically acceptable on one type of
`tissue may not be acceptable on another. For example,
`physiologically acceptable forces and temperatures within
`bone tissue may far exceed the amount of force and heat that
`is physiologically acceptable on a blood vessel or other soft
`tissue. Thus. the physical characteristics of both the poly
`meric material and the tissue site must be considered in
`determining maximum physiologically acceptable forces
`and temperatures for molding the polymer.
`It is preferred that the selected polymeric material be such
`that the amount of thermal energy needed to heat the
`material to its molding point can be transferred within a
`practical amount of time to thereby
`the length of
`time required for the surgical procedure and to minimize the
`amount of heat conducted out of the material and into the
`tissue.
`In one embodiment. the material is intended to provide
`mechanical support to tissue structures. In that embodiment.
`the material itself. and the ultimate therapeutic shape of the
`material. must provide a structure having su?icient mechani
`cal strength to withstand forces exerted upon the shaped
`material during its functional lifetime in vivo. This require
`ment is especially signi?cant when using materials that are
`expected to be biodegradeable after their mechanically func
`tional lifetime. Alternatively. the material need not be
`intended for structural support. Rather. the material may be
`used as a protective layer. a barrier layer, as an adhesive. or
`as a carrier of therapeutic agents. In that case. the material
`must be selected so that its function is not impaired either by
`biodegradation during its functional lifetime in vivo or by
`the process used to shape the material during implantation.
`The ability to provide varied degrees of mechanical support
`can be achieved by selecting dilfering polymeric materials
`or by altering the molecular weight distribution of materials
`comprising more than one polymer. In general. materials
`having higher molecular weights will provide a higher
`modulus and greater support than those materials having a
`lower molecular weight. Additionally. the material muse be
`selected such that the heating and reformation of the mate
`rial do not degrade or otherwise alter the release character
`istics of the material toward any therapeutic agents that may
`be incorporated into the material.
`
`45
`
`55
`
`60
`
`65
`
`Wavelength (nm)/laser
`
`Dye/Maximmn Absorption '
`
`457 Argon Ion
`488 Argon Ion
`
`514 Argon Ion
`676 Argon/Krypton
`647 Krypton
`676
`694 Ruby
`780 Semiconductor
`780
`810
`820
`830
`850
`870
`532 NeodymiumzYAG
`(frequency X2)
`
`355 NeodymiumzYAG
`(frequency X3)
`266, NeodymiumzYAG
`(frequency X4)
`
`Aeramine Yeliow (420 nm)
`Acridine Orange (489 nm),
`Fluorescein (491 nm)
`Eosin Y (514 nm)
`Methylene Blue (661 nm)
`Jenner stain (651 nm),
`Methylene Blue (661 nm)
`Prussian blue (694 nm),
`Copper Phtlralocyanine
`(795 nm in sulfuric acid),
`Indocyarrirre Green (775 nm)
`
`Ethyl Eosin (532 nmin
`ethanol); Erythrosin B
`(525 nm); Eosin Y (514 nm)
`Acridine (358 nm)
`
`Prussian blue (260 nm),
`
`Carbon black
`
`The selection of light source and chromophore is not
`intended to be limited solely to Those speci?ed above.
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1027 - Page12
`
`

`

`5.741.323
`
`15
`
`25
`
`7
`Rather. any combination that yields su?icient heating to
`render the polymeric material ?uent may be used.
`Any of a variety of methods known in the art of polymer
`processing may be used to form the polymeric material into
`its predeployment con?guration and, if necessary. to com—
`pound chromophores into the material. Among the pointer
`processing methods contemplated are solvent casting. injec
`tion molding. extrusion. solvent extraction and compression
`molding.
`The heating method of the present invention may be
`contrasted with conductive heating methods which use a
`heating element. as such techniques tend to require a greater
`thermal load and to heat more slowly. thereby having the
`potential to transfer signi?cant amounts of heat to the
`surrounding body tissue or ?uids. As noted previously
`however, absorption of light allows the polymeric article to
`be heated while transferring a minimum of energy to the
`surrounding tissue and ?uids. This is achieved by selecting
`either a Wavelength spectrum that is not readily absorbed by
`body tissue. a polymeric composition that absorbs substan
`tially all incident energy in the wavelength spectrum, or a
`combination of these characteristics.
`In one embodiment, the upper limit of the polymer
`temperature can be controlled using a dye which substan
`tially stops‘ absorbing optical energy once it reaches a certain
`temperature. Such so-called “thermochromic” dyes are com
`mercially available from Clark R&D Limited of Arlington
`Heights. 111. Thermochromic dyes exhibit a constant absorp
`tion below a lower critical temperature TL. Between TL and
`an upper critical temperature TU the absorption decreases
`from a constant value to nearly zero. Thermochromic dyes
`are further characterized generally in that the change of
`absorption with temperature is fully reversible. The incor
`poration of thermochromic dyes into polymeric materials
`allows constant absorption of energy when the polymer is
`cool with a decreasing energy absorption as the polymer is
`heated It is expected that the polymer temperature will
`reach a steady state at some point between TL and TU
`resulting from a balance between the energy absorbed by
`heat input from the light source and the energy lost by heat
`output to the surrounding tissue.
`For example. Type 47 thermochromic dye available from
`Clark R&D absorbs. at room temperature. light in the
`wavelength spectrum between about 600 and about 850 nm.
`The dye has 21 TL of 44 degrees C. and a TU of 58 degrees
`C. If this dye is compounded into a polymer having a
`melting temperature (TM) that falls between TL and TU, the
`resulting polymeric material will absorb light in the 600-850
`run spectrum and begin to heat. Once the polymeric material
`is heated to a temperature above TL. the absorption of the
`dye will decrease. thereby decreasing the rate of polymeric
`heating and preventing the polymeric material from achiev
`ing a temperature that may be harmful to it. and adjacent
`body tissue or surrounding body ?uids. Once the tempera
`ture of the polymeric material reaches T M. the polymer melts
`allowing it to pave an adjacent tissue surface. However.
`since the temperature rise will decrease and reach a steady
`state level where the energy input (reduced due to decreased
`dye absorption) equals the energy output (mediated by
`thermal boundary conditions) an upper thermal limit is
`achieved. Thermochromism thus is essentially a feedback
`mechanism for obtaining uniform heating of the entire
`article despite possible non-uniformity of illumination. The
`hottest regions of the polymer will absorb less light. allow
`ing other areas of the device to “catch up” in temperature
`during the heating stage. Thermochromic dyes can render
`instrumentation to measure temperature of the polymeric
`material unnecessary.
`
`8
`In addition. the use of thermochromic dyes may o?er
`advantages if the emitter is eccentrically located inside a
`shaping element such as a balloon. Since power density from
`the emitter is