(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`(43) Internationa} Publication Date
`8 February 2001 (08.02.2001)
`
`(51) International Patent Classification’:
`
`
`
`AOIF 2/06
`
`(21) International Application Number:
`
`PCT/US00/17116
`
`(22) International Filing Date:
`
`22 June 2000 (22.06.2000)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`(30) Priority Data:
`09/362,261
`
`English
`
`English
`
`28 July 1999 (28.07.1999)
`
`US
`
`(71) Applicant: SCIMED LIFE SYSTEMS,INC. [US/US];
`One Scimed Place, Maple Grove, MN 55311-1566 (US).
`
`(QUARTA
`
`(10) International Publication Number
`WO 01/08600 A2
`
`(81) Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CR, CU, CZ,
`DE, DK, DM,DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR,
`HU, ID,IL, IN,IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR,
`LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ,
`NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL. TJ, TM,
`TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW.
`
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), Eurasian
`patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European
`patent (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR. IE,
`IT, LU, MC, NL, PT, SE), OAPI patent (BF, BJ, CF, CG,
`Cl, CM, GA, GN, GW, ML,MR, NE, SN, TD, TG).
`
`(72) Inventors: WALAK,Steven; 5 Digren Road, Natick, MA
`01760 (US). DICARLO,Paul; 10 Starrett Avenue, Mid-
`dleboro, MA 02346 (US).
`
`Published:
`Without international search report and to be republished
`upon receipt ofthat report.
`
`(74) Agent: GRAD, Jonathan; Vidas, Arrett & Steinkraus,
`PA., 6109 Blue Circle Drive, Suite 2000, Minnetonka, MN
`55343-9131 (US).
`
`to the "Guid-
`For two-letter codes and other abbreviations, refer
`ance Notes on Codes and Abbreviations" appearing at the begin-
`ning ofeach regular issue ofthe PCT Gazette.
`
`(54) Title: MULTI-PROPERTY NITINOL BY HEAT TREATMENT
`
`124
`
` 124
`
`(57) Abstract: Medical devices may be made of shape-memory materials portions of which have beenheat treated to exhibit spatial
`variations in the stiffness of the material. Devices including stents, vena cava filters and guidewires may be constructed from such
`materials. Devices may also be made from shape-memory materials which have been locallyheat treated such that the superelasticity
`of the treated portion is destroyed while the remainder of the shape-memory material can transition between the martensitic and
`austenitic states.
`
`MEDTRONIC 1116
`
`A2
`01/08600
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`S
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`MEDTRONIC 1116
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`MULTI-PROPERTY NITINOL BY HEAT TREATMENT
`
`-1-
`
`BACKGROUNDOF THE INVENTION
`The present inventionis related to the use of shape memory materials in
`medical devices.
`A shape memory material can assumean initial high temperature
`and a deformed low temperature configuration
`and revert back to the
`configuration
`initial high temperature configuration upon the application of heat. The high
`temperature configuration of the material is set into the material or memorized during
`initial shaping step in which the material is maintained at a
`high temperature in a desired
`shape for a
`of time.
`
`an
`
`period
`This shape memory exhibited by metals results from the metal
`undergoinga reversible solid state phase transition. Specifically, the metal transitions
`from an austenitic state to a martensitic state with a decrease in temperature. The
`at which the transition begins is typically designated M, (martensite
`start
`temperature
`at which thetransition finishes is designated M,
`temperature) while the temperature
`As the metaltransitions from the austenitic state to the ©
`(martensite finish temperature).
`martensitic state it becomes more
`easily deformed. In the martensitic state, the metalis
`able to accommodatesignificant plastic deformation at an almost constantstress level.
`a metalin the martensitic state, the metal begins
`to return
`Uponheating
`to occursis
`to an austenitic state. The temperature
`at whichthis transition begins
`start
`temperature). Thetransition is complete
`temperature
`designated A, (Austenitic
`When A;
`is attained, the metal hasfully
`designated A; (Austenitic finish temperature).
`revertedto its initial, high temperature configuration.
`Shape-memory materials have been disclosed in US 3,012,882 to
`Muldaweretal. and US 3,174,851
`to Buehleret al. both of whichare incorporated
`herein by reference in their entirety.
`A variety of materials exhibit shape memory properties including binary
`metals such as Nickel-Titanium alloys including Nitinol. Doped Nickel-Titanium alloys
`may
`also exhibit shape-memory properties.
`The use of shape-memory metals in medical applications has been
`disclosed in a numberofreferences including US 5,197,978 to Hess, US 5,540,712
`
`at a
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`to
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`Kleshinski et al., US 5,597,378 to Jervis, US 5,769,796 to Palermoet
`are
`to Unsworth et al. The contents of the above patents
`
`incorporated
`
`al., US 5,846,247
`
`hereinin their
`
`entirety by reference.
`
`materials have been used,inter alia, in the
`production of
`Shape-memory
`or
`stents. Nitinol stents which are
`in the austenitic state and compressed
`fully expanded
`in the martensitic state have been disclosed. Thespecific Nitinol
`partially expanded
`alloy is chosen such that the stent will be in the austenitic state at
`body temperature.
`Prior to insertion into the body, the stent is maintained at low temperature
`to a desired
`to a
`temperature within the martensitic range. Upon delivery
`corresponding
`bodily location, the stent is warmed to at least the A; temperature and in the process
`toits desired final diameter.
`metals have been disclosed for use in other medical
`
`expanded
`
`Shape-memory
`devices as well.
`
`includingelasticity and stiffness, of a
`The physical properties,
`shape-
`be controlled via a
`memory metal may
`variety of factors including the chemical
`ofthe alloy and the treatment to which the alloy is subjected.
`composition
`Commonly assigned USpatent application 09/008684, incorporated hereinin its
`entirety by reference, discloses a process for improvingthe ductility of Nitinol via
`of a
`control of a numberof process parameters. The physical properties
`shape-memory
`material may also be controlled by heattreating the material. By selective local heat
`to destroy the austenitic-martensitic
`treatment of a
`shape-memory material, it is possible
`andstiffness.
`transition and/or changetheelasticity
`
`BRIEF SUMMARYOF THE INVENTION
`The present inventionis directed to medical devices which use
`shape-
`memory materials that have been differentially heat treated to exhibit spatially varying
`properties such as
`elasticity and stiffness.
`The present inventionis directed to medical devices having been formed,
`atleast in part, from shape-memory materials which have beenlocally treated to alter
`portions of the device which have not been
`their memory characteristics relative to
`a
`region of the shape-memory
`to the local heat treatment.
`Specifically,
`subjected
`material is treated to decrease the stiffness of the region relative to the remainderofthe
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`medical device. Desirably, the local treatment will destroy the superelastic properties of
`
`the locally treated region.
`to a stent having been formedat
`The inventionis directed in particular
`a
`least in part of a
`shape-memory material. The stent comprises
`plurality of cells
`arranged in columnsextending from oneendofthestentto the other. Adjacent columns
`of cells are interconnected. Thestent includesatleast one
`differently treated column of
`cells which has beentreated differently from the remainderofthe stent to have different
`from the remainderofthestent.
`shape-memory properties
`The invention is also directed to a stent whereinat least one of the
`a reducedelasticity relative to the remainderofthe
`
`columns is characterized by
`
`columns.
`
`The inventionis also directed to a stent whereinat least oneof the
`a reducedstiffness relative to the remainderof the columns.
`columnsis characterized by
`Theinventionis further directed to a stent whereinat a desired
`longitudinal column ofcells doesnot have superelastic
`temperature range,at least one
`properties while the remainderofthe longitudinal columns do have superelastic
`
`properties.
`
`Theinventionis also directed to a stent having been formed of a
`shape
`a
`plurality of spaced segments. Adjacent spaced
`memory material and comprising
`one or more connector sections. Each segment
`segments are connected to each other by
`a series of interconnected cells. Desirably, the cells in plan view are of
`comprises
`to a different heat
`polygonal configuration. The segments have been subjected
`treatment than the connector sections.
`The inventionis also directed to a stent having been formed of a
`shape
`a
`plurality of spaced segments with adjacent spaced
`memory material and comprising
`one or more connector sections. Each segment
`segments connected to each other by
`a series of interconnected cells. Desirably, the cells in plan view are of
`comprises
`polygonal configuration. The segments have a reducedstiffness relative to the
`are not
`connectorsections. Desirably, the segments
`superelastic.
`In another embodiment, the inventionis directed to a medical guidewire
`shape-memory metal. Different portions of the
`having been formedatleast in part of a
`shape-memory metal have been treated differently to have different shape-memory
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`to a local heat
`at least one
`portion of the guidewire is subjected
`properties. Desirably,
`treatment resulting in a reducedstiffness compared with the remainder of the guidewire.
`can be prepared. Via the localized heat
`In this way, a
`of desired flexibility
`guidewire
`guidewire may be prepared in whichatleast a
`a
`portion thereofretainsits
`treatment,
`shape memory properties while a
`portion thereof loses its shape memory properties.
`In yet another embodiment,the inventionis directed to
`implantable
`medicalfilters such as vena cava filter having been formed of shape-memory materials.
`At least a
`of the shape-memory materialis differently treated to alter the shape-
`portion
`of the material relative to the untreated shape-memory material.
`memory properties
`will be heat treated and exhibit a
`Desirably, the differently treated portion
`deformation relative to the remainderofthe filter.
`tendency toward plastic
`
`greater
`
`BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
`alloy which can
`Figure 1 illustrates the stress-strain behavior of an
`a transition from a martensitic state to an austenitic state and the stress-strain
`
`undergo
`behaviorofthe alloy following additional heat treatment.
`alloy which can
`Figure 2 illustrates the stress-strain behavior of an
`transition from a martensitic state to an austenitic state and the stress-strain
`undergo
`behaviorofthe alloy following additional heat treatment.
`Figure 3a is a side-elevational view of a stent made in accordance with
`the present invention.
`Figure 3b is a side-elevational view of the stent of Fig. 3 in which the
`treated column of cells has not been fully expanded.
`Figure 4ais a side elevational view of a stent made in accordance with
`the present invention.
`Figure 4b is a side elevational view ofthe stent of Fig. 4a after it has
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`been bent.
`
`Figures 5a and 5b are views of embodiments ofthe invention in which
`connecting segmentshavebeentreated.
`Fig. 6a showsa side elevational view of an inventive guidewire.
`Fig. 6b showsthe guidewireof Fig. 6a in a bent configuration.
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`
`Fig. 6c showsthe guidewire of Fig. 6b after it has been released from the
`
`distal tip
`
`Fig.
`
`bent configuration.
`Fig. 6d shows a side elevational view of an inventive guidewire whose
`has beentreated to exhibit a reduced stiffness.
`7a showsa side elevational view ofa prior
`7b showsthe guidewire of Fig. 7a in a bent configuration.
`Fig.
`Fig. 7c shows the guidewire of Fig. 7b after it has been released from the
`bent configuration.
`Fig. 8 showsa side elevational view of an inventive vena cavafilter.
`
`art
`
`guidewire.
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`DETAILED DESCRIPTION OF THE INVENTION
`While this invention may be embodied in many different forms, there are
`described in detail herein specific preferred embodimentsof the invention. This
`ofthe principles of the invention andis not intended to
`description is an
`exemplification
`limit the invention to the particular embodimentsillustrated.
`Thepresent inventionis directed to the selective treatmentof portions of
`a
`a medical device containing
`shape memory material. More specifically, the invention
`is directed to differential treatment of the shape memory material in a medical device to
`achieve different physical properties in different portions of the device.
`shape memory material such as Nitinol
`Medical devices made of a
`typically have shape memory characteristics. The shape memory characteristics of the
`be altered by heat treating the material. By locally treating portions of a
`material may
`a metal with spatial variations in the
`to
`shape-memory metal,it is possible
`produce
`andstiffness of the metal. The locally treated portionswillinitiate plastic
`elasticity
`that have not beenlocally treated.
`deformation at a lowerstrain than the portions
`onthe extent of the heat treatment, the material may simply have a reduced
`Depending
`or the superelasticity of the locally treated portion
`stiffness in the locally treated portion
`may be destroyed with the locally treated portion beingplastically deformable.
`(solid line) is shown for a
`a stress-strain curve
`In Fig. 1,
`shape-memory
`(dashedline) for the same material following
`material. The stress-strain curve
`additional heat treatmentof the material is also shown. As a result of the heat treatment,
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`-6-
`
`as shown in Fig. 1 and the material
`
`to a
`
`the material has a reduced load and unload plateau,
`initiates plastic deformation at a lowerstrain level.
`It has also been foundthat with sufficient heat treatment, the superelastic
`destroyed. In Fig. 2, the stress-strain curve
`properties of the material may be
`(solid line)
`is shown for a
`shape-memory material. The stress-strain curve
`(dashedline) for the
`same material following significant additional heat treatment to eliminate the
`of the material is also shown in
`Fig.2.
`superelastic properties
`The shape memory material based medical deviceis typically subject
`annealing processing conditions as are known inthe art.
`first annealing using standard
`the device will be annealed for about 5 minutes to about 40 minutesat a
`
`Desirably,
`temperature ranging from about 400 C to about 575 C. More
`desirably, the device will
`be annealed for about 10 minutes to about 15 minutes. Also more
`desirably, the device
`from about 450 C to about 550 C. Shorter or
`
`will be annealed at a
`
`temperature ranging
`or lower temperatures, depending
`longer periods may be used as may higher
`material being annealed and the desired properties of the material.
`Following the first annealing, the medical device is subjected
`further. Thelocalized
`second, localized, annealing step in which the deviceis
`heated
`heat treatment of the desired shape-memory material medical device may be
`accomplished by any suitable method. One such suitable method involves the use of
`electrical resistance heating. Electrical leads are attached across the desired portion of
`the device and a current allowed to pass therethrough. Becauseofthe resistance of the
`shape-memory metal, the desired portion of metal heats up thereby further annealing the
`to a stent made ofNitinol wire (0.014 inch
`material. The technique has been applied
`diameter). Leads were attached to a desired portion of the stent and 4 Volts applied
`to
`the wire. After 20 seconds, the desired portion of the wire transitioned from a
`state to a
`state.
`
`on the
`
`to a
`
`superelastic
`
`plastic
`a heatedinert gas jet
`Another suitable method involves applying
`selectively heat a desired portion of the device.
`desired portion of the medical deviceto
`Yet another method involves the use of an induction coil. An induction coil may be
`over a desired portion
`of the medical device to effect induction heating of the
`placed
`be usedto selectively heat
`desired portion of the medical device. A laser may
`also
`desired regions of the medical device. The desired regions of the medical device may
`
`toa
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`Wp
`
`treating fluid such as a
`also be brazed. The medical device may also be placed in a heat
`salt bath or a fluidized sand bath with appropriate
`sections of the device insulated.
`of the method chosen for the second annealing step, the
`Regardless
`second annealing step is typically carried out at a
`temperature of about 550 C to about
`600 C for about five minutes to about 20 minutes. At such temperatures,thestiffness of
`the material will be reduced. As with the first annealing step, the exact time and
`onthe material chosen(i.e.its
`temperature of the second annealing step depends
`and on the form of the material (for example, in wire form or in sheet
`composition)
`form). In certain cases, it may be desirable for the second annealing step to be carried
`of time and at lower or
`out overshorter or
`higher temperatures than those
`longer periods
`disclosed above. In one embodimentofthe invention,it is desirable to
`locally heat treat
`the material during the second annealing step to destroy the shape memory feature of the
`ofthe stent at temperatures of
`metalin the treated region by treating the desired portions
`about 650 C to about 700 C and above. At temperatures of about 600 C to about 650 C,
`on the duration
`whetherthe heat treatment destroys the shape memory feature depends
`ofthe treatment and the composition
`of the material.
`The invention contemplates localized heat treating of a
`variety of medical
`andfilters such as vena cava filters. For
`devices including stents, medical guidewires
`the purposesofthis disclosure,it is understoodthat the term 'stent' is intended to include
`ofrelated devices includingstents,grafts and stent-grafts in particular and
`a
`variety
`in general.
`endoluminalprostheses
`as shown in Fig. 3a, the invention is directed to a
`In one embodiment,
`ofa plurality of cells 104 arranged in columns
`at 100, comprised
`stent, shown generally
`108 extending from one end 112 ofthe stent to the other end 116. Adjacent columns
`108 of cells 104 are interconnected. Thestent includes at least one
`differently treated
`column 108aofcells 104a which has beentreated differently from the remainderof
`columns 108b to have different shape-memory properties from the remainder of the
`
`stent.
`
`an
`Desirably, differently treated column 108a will be characterized by
`increased tendencyto plastic deformationrelative to the remainderofthe stent and will
`ofthe differently treated
`be plastically deformable. More desirably, the superelasticity
`as a result of the heat treatment.
`will be destroyed
`
`portion
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`The invention also contemplates treating the column(s)
`treated portion loses its shape memory characteristic.
`Fig. 3b showsthe stent of Fig. 3a in a
`state. Untreated
`partially expanded
`columns 108b are shown in an
`expandedstate, having been exposedto a sufficient
`temperature to cause the metalto transitionto its austenitic state. Treated column 108a
`is in an
`been
`unexpandedstate, the
`superelastic properties of the material having
`
`locally
`
`suchthat the
`
`destroyed.
`
`stent 100 may be further
`or
`
`Although columns 108b are
`fully expanded,
`a
`radially outward force to the stent
`expanded by applying
`thereby opening
`column(s) 108a. A balloon catheter or other expansion device may be
`treated
`expanding
`used to effect such a
`ofthe stent.
`‘touch-up’ expansion
`a column of cells of different shape memory properties
`By providing
`in concert with the expansion of the remainder ofthestent, the
`expanded
`later be 'touched up’ via mechanical expansionof the cells of the treated
`column tobetter fit in a lumen.
`
`which are not
`
`stent may
`
`Another stent formed in accordance with the present invention is shown
`at 100 in Figs. 4a and.4b. One or more circumferential bandsof cells 122 is
`generally
`specially treated, in accordance with the invention. Bands 122 have different shape
`memory properties from the cells in the remainderofthe stent. For example, band(s)
`122 may
`to
`being deformedat
`stent 100 prior
`be plastically deformable. Fig. 4a depicts
`stent 100 after it has been bent at band 122. The
`band 122 while Fig. 4b depicts
`remainderof the stent which has not been subjectedto the
`ofthe material.
`
`treatment retains the
`
`special
`
`shape memory properties
`at 100in Fig.
`Theinventionis also directed to the stent shown generally
`ofa plurality of spaced segments 120. Each segment 120 is desirably
`5a, comprised
`comprised of a series of interconnectedcells 124. Desirably, cells 124 will be of
`polygonalconfiguration in plan view. Moredesirably, they will be hexagonal.
`one or more connector
`Adjacent spaced segments 120 are connected to each other by
`at an
`oblique angle relative to
`sections 128. Connector sections 128 may be disposed
`the longitudinal axis 180 of the stent as shown in Fig. Sa or
`they may be substantially
`or
`parallel to the longitudinal axis 180 as shown in Fig. 5b. They may bestraight
`to a local heat treatment, in accordance with
`curved. Segments 120 have been subjected
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`the invention. Desirably, segments 120 will be of lowerstiffness than connector sections
`128 as a result of the heat treatment.
`
`Stent 100 may be madeof
`any suitable
`shape-memory material
`including
`shape-memory metals such as Nitinol. Nitinol with a
`composition of about 55.75% (by
`weight) nickel and 44.25% (by weight) titanium may
`be particularly well suited for use
`in the present invention. The stent may be made of shape-memory wire or a sheet or
`tube of shape-memory material.
`The invention is also directed to stents similar to those shown in Figs. 5a
`and 5b, such as those disclosed in US 08/942162 incorporated hereinin its entirety by
`are
`reference, wherein the connector sections and the segments
`to different heat
`treatments.
`
`subject
`
`The stent
`
`flexibility corresponding
`
`configurations of Figs. 3-5 are intended to be exemplary.
`may
`treated
`Stents with other designs
`be
`similarly.
`In another embodiment, the invention is directed to medical guidewires
`made of shape-memory materials, portions of which have been differentially treated. In
`a medical guidewire, such as that shown at 200 in Fig. 6a, is
`one aspectof the invention,
`specially treated toward distal end 204 of the guidewire. Region 208 ofthe device is
`heat treated to increase the tendency toward
`plastic deformation of the treated portion
`to have a
`relative to the remainderof the guidewire. This, in turn, allows the guidewire
`greater flexibility and a
`of
`to the
`region of reduced
`region
`locally treated section of the guidewire.
`Figs. 6b and Fig. 6c illustrate the guidewire of Fig. 6a as it is bent and
`208 has a
`greater tendency toward
`released. In Fig. 6b, guidewire 200 is bent.
`Region
`plastic deformation. The remainder 212 of guidewire 200 is in the austenitic state and
`thus deformselastically. The guidewire of Fig. 6b is shown in Fig.6c after it has been
`released from its bent position. Locally treated region 208 remains bent while austenitic
`to
`to their configuration prior
`being bent. Thus, by using
`regions 212 recovery fully
`to
`Nitinol which has been treated to have
`spatially varying properties,it is possible
`deformed within the body.
`guidewire which may be
`permanently
`also be used to reducethestiffness ofthe tip
`A localheat treatment may
`into the body. Thisis illustrated
`inserting the guidewire
`
`prepare a
`
`of the guidewireprior
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`to
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`schematically in Fig. 6d. Distal end 204 of guidewire 200 has been subject
`additional heat treatment to reduce thestiffness of the distal end relative to the
`
`to an
`
`remainderof the guidewire. If the superelasticity is completely destroyed,
`a
`bend may
`to
`in the guidewire, thereby allowing
`beplaced
`as desired.
`
`physician
`
`shape
`
`a
`
`permanent
`a
`
`guide wire
`
`For the sake of comparison,a fully austenitic guidewire is shown in
`variousstates in Figs. 7a-c. Fig. 7a shows guidewire 200. The entire
`guidewireis in the
`200 is shown in a bent configuration. A
`austenitic state 212. In.
`Fig. 7b, guidewire
`208 is in a stress-induced martensitic state while the remainder 212 of
`
`small region
`guidewire 200 is in the austenitic phase. Upon release of the guidewire,
`returns to the configuration it had
`to
`Fig. 7c, the entire
`being bent. The
`guidewire
`is in the austeniticstate.
`entire guidewire
`In yet another embodiment,the inventionis directed to medical filters
`materials. Fig. 8 shows a
`treated
`made,at least in part, of differentially
`shape-memory
`at 300. Vena cavafilter 300 is similar in
`vena cavafilter generally
`to that
`design
`disclosed in commonly assigned USPatent 5,709,704 to Nott et
`al., the content of which
`at least in
`is incorporated hereinin its entirety by reference. Filter 300 is constructed,
`part, of a
`shape memory material. Filter 300 includes a
`single cell 304 in which the
`shape-memory materialis differentially heat treated to increase the tendencyto plastic
`8 shows an
`deformation of the desired portion of the filter. Although the filter of Fig.
`cell has been heat treated differently, the invention
`embodimentin which only
`single
`ofcells has been differently treated.
`contemplates other embodiment in whicha plurality
`columnsof
`Onesuchvariant involves a filter
`one of the
`of
`
`as shown in
`
`prior
`
`cells,
`
`10
`
`15
`
`20
`
`25
`
`30
`
`multiple
`comprised
`to a different heat treatment.
`
`columns having been subjected
`The invention may
`materials.
`bepracticed generally with shape-memory
`Desirably, binary shape-memory metals such as Nitinol or other alloys of Nickel and
`Titanium will be used. The invention also contemplates the use of doped binary metals
`as well. Suitable dopants include Chromium, Niobium and Vanadium. Additional
`are disclosed in WO 95/31945,the contents of which are
`suitable shape-memory alloys
`incorporated herein in their entirety by reference.
`The abovedisclosure is intended to be illustrative and not exhaustive.
`This description will suggest many variations and alternatives to one of
`ordinary skill in
`
`

`

`WO 01/08600
`
`PCT/US00/17116
`
`this art. All these alternatives and variations are intended to be included within the
`
`j=
`
`scope of the attached claims. Those familiar with the art may recognize other
`are also
`to the specific
`embodiments described herein which equivalents
`equivalents
`intended to be encompassedby
`the claims attached hereto.
`This application claims priority from US
`incorporated herein by reference.
`
`No. 09/362261
`
`Application
`
`

`

`WO 01/08600
`
`PCT/US00/17116
`
`-12-
`
`Whatis claimedis:
`A stent formedatleast in part of a
`I.
`shape-memory material, the stent
`comprised
`of a
`plurality of cells having been formedofthe shape memory material and arranged in
`columns extending from oneendofthestent to the other, adjacent columnsofcells
`at least one
`interconnected, the stent
`differently treated column ofcells which
`including
`has beentreated differently from therest of the cells to have a differentstiffness.
`The stent of claim 1 wherein the at least one
`2.
`differently treated column is
`a
`plastic deformation than the remainderofthe
`
`greater tendency
`
`toward
`
`characterized by
`stent.
`
`3.
`
`The stent of claim 1 wherein the strain necessary to initiate plastic deformation
`is lowerin the differently treated column of cells than in therest ofthe cells.
`Thestent of claim 1 whereinall of the columns have been annealed in
`4,
`annealing step at a first temperature
`andthe at least one
`differently treated column of
`cells has been annealed for an additional period of time at a second temperature in
`excessofthe first temperature.
`The stent of claim 1 wherein the columnsare
`5.
`
`first
`
`arranged substantially parallel
`
`to
`
`the longitudinal axis of the stent.
`Thestent of claim 1 wherein the shape memory material is a Ni-Tialloy.
`6.
`a
`Thestent of claim 6 wherein the Ni-Ti alloy further comprises
`dopantselected
`from the group consisting of Chromium, Niobium, Vanadium and combinationsthereof.
`Thestent of claim 1 wherein theat least one
`8.
`differently treated column has
`shape-memory properties than the remainderofthestent.
`a
`plurality of cells having been formed of a
`A stent
`9.
`shape memory
`comprising
`material, the cells arranged in columns extending from one endofthe stent to the other,
`adjacent columnsinterconnected,at least oneless stiff column characterized by
`a
`greater
`tendency toward plastic deformation than the remaining columns.
`The stent of claim 9 wherein the reducedstiffness column is not
`10.
`remaining columns are
`superelastic.
`The stent of claim 9 wherein the reducedstiffness column has been heat treated
`
`Ts
`
`different
`
`the
`
`11.
`
`superelastic and
`
`differently from the other columns.
`having been formed of a
`A stent
`12.
`
`shape-memory material, the stent
`
`comprised
`
`10
`
`15
`
`20
`
`25
`
`30
`
`

`

`WO 01/08600
`
`PCT/US00/17116
`
`-13-
`
`of a
`
`one or more
`
`plurality of spaced segments,
`adjacent spaced segments connected to each other by
`connectorsections,
`wherein the segments have been heattreated differently than the
`connectorsections.
`The stent of claim 12 where each segment comprises
`
`13.
`
`series of interconnected
`
`cells.
`
`14.
`
`The stent of claim 13 wherein the cells in plan
`
`view are of polygonal
`
`configuration.
`The stent of claim 12 wherein the connector sections are reducedin stiffness
`
`15.
`
`10
`
`relative to the segments.
`The stent of claim 12 madeofNitinol.
`
`16.
`
`17.‘
`
`The stent of claim 12 madeofwire.
`
`straight.
`
`substantially parallel
`
`disposed
`
`at an
`
`oblique
`
`are
`
`shape-memory material,
`of spaced segments,
`plurality
`adjacent spaced segment being connected to each other by
`
`the stent
`
`comprised
`
`18.
`
`19.
`
`angle
`
`21.
`
`15
`
`20
`
`25
`
`are
`The stent of claim 12 wherein the connector segments
`The stent of claim 12 wherein the connector segments are
`to the longitudinal axis of the stent.
`The stent of claim 12 wherein the connector segments
`20.
`to the longitudinal axis ofthestent.
`A stent formed of a
`
`of a
`
`one or more
`
`connector
`
`sections,
`wherein the segments and the connectors are made of the same
`the stiffness of the connectors
`differing from thestiffness of the segments, the segments
`differently from the connectors.
`having been treated
`‘The stent of claim 21 whereinthestiffness of the segments exceedsthe stiffness
`22.
`
`material,
`
`of the connectorsections.
`The stent of claim 21 wherein each segment comprises
`
`23.
`
`a series of interconnected
`
`cells.
`
`30
`
`proximal end and a distal end, the guidewire
`A medical guidewire having
`24.
`having been formedatleast in part of a
`shape-memory metal and wherein different
`
`a
`
`

`

`WO 01/08600
`
`PCT/US00/17116
`
`-14.
`
`portions of the shape-memory metal have beentreated differently
`
`to have different
`
`shape-memory properties.
`25.
`The guidewire of claim 24 wherein different portions of the
`metal are characterized by different stiffnesses.
`metalincludesa first
`26.
`The guidewire of claim 24 wherein the
`shape-memory
`portion and a second
`portion,the first and second portions having been annealed in a
`first annealing step at a first temperature, the second
`portion annealed having been
`annealed for an additionalperiod
`oftime at a second temperaturein excessofthefirst
`
`shape-memory
`
`10
`
`15
`
`20
`
`25
`
`temperature.
`The guidewire of claim 24 wherein the distal end of the guidewire has a lower
`27.
`endofthe guidewire.
`stiffness than the proximal
`The guidewire of claim 24 wherein atleast a
`portion of a
`28.
`region extending from
`to about 50 cm from the distal end of the guidewire has a
`the distal end of the guidewire
`lowerstiffness than adjacent regions of the guidewire.
`The guidewire of claim 24 wherein a portion ofthe shape-memory metal has
`29.
`ofthe portion.
`destroy the shape-memory properties
`metalis a Nickel-
`The guidewire of claim 24 wherein the
`
`shape-memory
`
`been heattreated to
`
`30.
`
`a
`
`Titanium alloy.
`31.
`The guidewire of claim 30 wherein the Nickel-Titanium alloy further comprises
`dopantselected from the group consisting of Chromium, Niobium, Vanadium and
`combinationsthereof.
`Amedical device formed at least in part of a
`32.
`shape-memory material wherein at
`least a first portion of the shape-memory material may transform between a martensitic
`state and a austenitic state and at least a second
`portion of the shape-memory material is
`to the austenitic state at the same time asthefirst portion.
`incapable of transforming
`33.
`The medical device of claim 32 wherein the second portion has been heattreated
`incapable of transformingto the austenitic state.
`
`to be
`
`

`

`WO 01/