(12) United States Patent
`Jervis
`
`US006306141B1
`(16) Patent N6.=
`US 6,306,141 B1
`(45) Date of Patent:
`Oct. 23, 2001
`
`(54) MEDICAL DEVICES INCORPORATING SIM
`ALLOY ELEMENTS
`
`(75) Inventor: James E. Jervis, Atherton, CA (US)
`
`(73) Assignee: Medtronic, Inc., Minneapolis, MN
`(Us)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`-
`-
`patent is extended or adJusted under 35
`U'S'C' 154(k)) by 0 days'
`
`(21) APP1-N0-108/483,291
`-
`_
`(22) Flled'
`
`Jun‘ 7’ 1995
`Related U_S_ Application Data
`
`(60) Continuation of application No. 07/956,653, ?led on Oct. 2,
`1992, which is a division of application No. 07/682,243,
`?led on Apr. 9, 1991, now Pat. No. 5,190,546, which is a
`division of application No. 07/252,019, ?led on Sep. 27,
`1988, now Pat. No. 5,067,957, which is a continuation of
`application No. 07/177,817, ?led on Mar. 30, 1988, now
`abandoned, which is a continuation of application No.
`07/047,824, ?led on May 8, 1987, now abandoned, which is
`a continuation of application No. 06/865,703, ?led on May
`21, 1986, now Pat. No. 4,665,906, which is a continuation
`of) apcplicaéion No. 06/541,852, ?led on Oct. 14, 1983, now
`
`a an one .
`
`(51) Int. CI.7 ................................................... .. A6113 17/56
`
`3,605,725
`3,620,212
`3,729,008
`377407839
`
`9/1971 Bentov .......................... .. 128/2.05 R
`11/1971 Fannon, Jr.
`.. 128/130
`4/1973 Berkovits
`128/418
`6/1973 OtPe et al- -
`29/628
`
`3,757,768
`
`9/1973 Kllne . . . . . . . . . . . .
`
`. . . .. 128/2M
`
`1/1974 Johnson et al- ~~
`2/1974 Antoshkiw
`12/1974 Lerner ........ ..
`3/1975 Al?di et a1:
`6/1975 Lerner
`
`377867806
`3,789,841
`3,857,391
`378687956
`3,889,666
`
`3,890,977
`3,939,828
`3,960,147
`4,033,331
`4,035,007
`4,037,324
`4,080,706
`4,149,911
`4’17O’99O
`
`128/92 YN
`128/2.05
`.. 128/127
`
`..
`
`604/281
`6/1975 Wilson .... ..
`..
`2/1976 MOhI et al.
`128/92 B
`6/1976 Murray .... ..
`128/92B
`7/1977 Guss etal.
`128/2M
`7/1977 Harrison et al.
`.. 285/381
`7/1977 Andreasen
`433/24
`3/1978 Heilman
`29/173
`4/1979 Clabburn ........ ..
`. 148/11.5 R
`10/1979 Baumgart et al' """""" " 128/92 YN
`-
`-
`(Llst Connnued on next page)
`
`FOREIGN PATENT DOCUMENTS
`8301576
`5/1983 (AU) _
`3086384
`1/1985 (AU)
`
`(List continued on next page.)
`OTHER PUBLICATIONS
`
`Jackson, “55—Nitinol—The Alloy with a Memory: Its Physi
`Cal
`Metallurgy,
`Properties,
`and
`Applications,”
`NASA—SP5110 (1972).
`
`(52) us. c1. .............................................................. .. 606/78
`
`(Listcontinue91 on next page)
`
`(58) Field of Search .............................. .. 606/78, 60, 108,
`606/62, 68, 200, 195, 198; 623/1
`
`(56)
`
`References Cited
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`
`3,348,548
`3,416,531
`3,419,010
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`3,558,369
`
`10/1967 Chardack ........................... .. 128/418
`12/1968 Edwards
`~~ 128/348
`12/1968 Williamson
`..
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`3/1970 Almen ...... ..
`..
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`6/1970 Ackerman
`128/418
`11/1970 Tafeen
`128/221
`1/1971 Wang et al. ...................... .. 148/115
`
`Primary Examiner—Justine R. Yu
`.
`(74) Attorney, Agent, or Fzrm—Sheldon & Mak
`57
`ABSTRACT
`(
`)
`Medical devices which are currently proposed to use ele
`ments made from shape memory alloys may be improved by
`the use of stress-induced inartensite alloy elements instead,
`The use of stress-induced martensite decreases the tempera
`ture sensitivity of the devices, thereby making them easier to
`install and/or remove.
`
`22 Claims, 4 Drawing Sheets
`
`LII/IIII/IIII/I/II
`
`\
`1A
`I \IIIIIIIIIIIIIIII
`
`Edwards Exhibit 1001, p. 1
`
`

`

`US 6,306,141 B1
`Page 2
`
`US. PATENT DOCUMENTS
`
`OTHER PUBLICATIONS
`
`4,197,593
`471983081
`
`4/1980 Kaster et al. ........................... .. 3/15
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`
`MaZer, “Therapeutic Emboiization of the Renal Artery With
`Gianturco Coils: Limitations and Technical Pitfalls,” Radi
`
`,
`
`,
`
`
`
`..................... .. aw ns, r. ..
`
`
`
`OlOgy) _
`
`_
`
`4 233 690
`4:307:723
`4,310,354
`4,378,811
`
`_ _ _ _ _ _ __ 623/2
`11/1980 Akins _ _ _ _ _
`128/349 R
`12/1981 Finney ......... ..
`75/211
`1/1982 Fountain e161.
`4/1983 Levitan .............................. .. 128/757
`
`Perkins, “Shape Memory Effects in Alloys,” Plenum Press,
`NY 1975 - (PP- 29—59, Rodriguel article; PR 59—89, ShimiZll
`art1619; PP- 273—304, Perklns art1616-)
`Robinson, “Metallurgy; Extraordinary Alloys that Remem
`
`
`
`Luther ................................ .. gicigegk "
`
`
`
`ber their Past,” Science) Vol' Wagner, “What You Can Do With that ‘Memory Alloy,’ ” NO_ (May,
`
`
`
`
`
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`
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`
`4,509,517
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`
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`4,586,335
`
`4,601,283
`476167656
`4,665,906
`4,925,445
`5,190,546
`1001034
`
`128/6
`1/1984 Ueda
`4’427’OOO
`6/1984 Utsugi .................................... .. 128/4
`4:452:236
`4,485,805 * 12/1984 Foster, Jr, ,,
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`4,485,816
`12/1984 Krumme
`128/334 R
`
`Materials Engineering, 70 (1969) Oct. pp. 28—31.
`Wasilewski, “The Effects of Applied Stress on the Marten
`sitic Transformation in TiNi,”Metallurgical Transactions, 2:
`NOV. 1971, pp. 2973—2981.
`
`12/1984 Tanaka . . . . . . .
`1/1985 Gianturco
`
`. . . . .. 433/20
`128/1 R
`
`Wayman, “some Applications of Shape_MemOry Alloys,”
`Journal OfMemlS Jun 1980 pp‘ 129_137_
`
`3/1985 Quin ......... ..
`
`148/402
`
`4/1985 Zibelin ............................... .. 128/319
`4/1985 Balko e161. ....................... .. 128/1 R
`
`_
`
`_
`
`’
`
`_
`
`’
`
`’
`
`_
`
`PhYSIk 1“ Unserer Z61}, 1977’ Nr- 2’ Verlag Chemle GmbH>
`56116 33> and translatlon thereof
`
`9/1985 McCoy . . . . . . . . . . .
`128/1 R
`12/1985 Hodgson et al
`5/1986 Hosoda et a1. ....................... .. 60/528
`
`. . . . .. 604/95
`
`Dotter, Charles T., Transluminal Expandable Nitinol Coil
`
`Stent Grafting: Preliminary Report, Radiology, vol. 147, pp.
`259_26()_
`
`7/1986 Chikama ................................ .. 128/4
`“V1986 Nicholson et a1‘
`128660
`5/1987 Jervis ............................ .. 128/92 YN
`5/1990 Sakamoto 61 a1. .
`3/1993 JCIVIS ................................... .. 606/78
`12/1976 (CA) .................................... .. 128/93
`
`FOREIGN PATENT DOCUMENTS
`2703529
`3/1978 (DE) _
`3225151A1
`1/1984 (DE) .
`102685
`5/1983 (EP) -
`0105669
`4/1984 (EP) -
`0129634
`1/1982 (EP) .
`0140621
`52985 EEP;
`0145166
`6/1985 (EP)
`8211061
`12/1983 (FR) _
`1600000
`10/1981 (GB) ............................ .. F16L/21/00
`2106190
`4/1983 (GB) -
`2114005
`8/1983
`
`0132344
`
`1 198
`
`EP .
`
`............................. .. 128/92 YN
`
`a
`
`.
`_
`Cragg, et al.,Radiology, (Apr. 1983) vol. 147, pp. 261 263.
`Schetky, L- McDonald, “Shape Memory A110yS”,5Ci@”li?C
`America, Nov- 1979, PP- 74—82
`Buehler, et aL, “55_NitinO1 Unique Wire
`Memory”, Wire Journal Jun 1963, pp 41_49_
`Portsmann, et al., “P Wave Synchronous Pacing Using
`Anchored Atrial Electrode Implanted Without Thorac
`otomy”, Jul. 1972, TheAmerican Journal of Cardiology vol.
`30, PR 74—76
`Baumgart, et al., “Memory Alloys—Properties, Phenomeno
`logical Theory and Applications”, 1976 (Reference #1 from
`Opposition)
`Bennsmann, et al., “Study of the Memory Alloy N1ckel—T1
`tanium and Observations on its Application in the Field of
`Medicine”, 1979 (Reference 2 from Opposition).
`Bennsmann, et al_, “Osteosynthesis Staples Made of Nick
`el—Titanium, Manufacture Preliminary Experiments and
`Clinical Use Thereof”,
`from Opposition)~
`
`.
`
`.
`
`57_75647
`57-95452
`57-119744
`5825140
`
`44047
`50951
`5841546
`5844047
`52822;;
`6220827
`5997115
`6045356
`100956
`6476824
`940759
`850067
`1110447
`1113110
`
`'
`
`5/1982 (JP)
`6/1982 (JP).
`7/1982 (JP) .
`2/1983 (JP) .
`(g)
`3/1983 Eng:
`3/1983 (JP) _
`3/1983 (JP).
`3/1983 (JP) .
`21122; 81;;
`4/1984 (JP) _
`6/1984 (JP) .
`3/1985 (JP)-
`6/1985 (JP) .
`3/1989 JP .
`11/1980 (sri) .............................. .. 128/92 YN
`7/1981 (SU)
`128/92 YN
`8/1984 (SU) .............................. .. 128/92 YN
`9/1984 (SU) .............................. .. 128/92 YN
`
`Baumgart, et al., “Mechanical Problems in the Use of the
`Memory Effect for Osteosynthesis Plates”, 1977 (Ref. #4
`from OPPOSmOn)
`Suzuki, Yuchi, Shape Memory and Super—Elasticity Effects
`in Ni—Ti Alloys. (Translation provided).
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`Ed., V01. 20, pp. 7—26—7—36.
`Ling, et al., Variation in the Shape Recovery Temperature in
`Ni—Ti Alloys, Mat’ls Sc. & Eng., vol. 48, pp. 241—247
`(1981).
`W.
`b s d
`N Sp 1
`hd -
`rt 0 ont1c
`atana e, tu 1es on eW u ere ast1c 1— 1
`Wire, J. Jap. Soc. for Dental Apparatus & Mat’ls., vol. 23,
`NO- 61, PP- 47—57 (1981)
`Oonishi, Clinical Magazine: Orthopaedic Surgery, 32, p.
`1180 (1981)
`
`Sullivan Variable stiffening Device for colonscopy, Gas
`trointestinal Endoscopy, vol. 36 No. 6, pp. 642—643 (1990).
`
`* cited by examiner
`
`Edwards Exhibit 1001, p. 2
`
`

`

`U.S. Patent
`
`0a. 23, 2001
`
`Sheet 1 014
`
`US 6,306,141 B1
`
`STRESS
`(U)
`
`A
`GM ‘"1
`
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`8A
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`STRESS
`(U)
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`GA
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`
`B
`i
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`
`STRAIN (8)
`
`[12. 1
`
`| D
`
`B
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`8B
`
`|
`I
`
`STRAIN (6)
`
`[12.2
`
`Edwards Exhibit 1001, p. 3
`
`

`

`U.S. Patent
`US. Patent
`
`0a. 23, 2001
`Oct. 23, 2001
`
`Sheet 2 014
`Sheet 2 0f 4
`
`US 6,306,141 B1
`US 6,306,141 B1
`
`[12.3
`
`
`i’IlllIIIIIIIIIIIIIIIIIIIIIIIIIIII’o9
`
`.- .\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
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`
`Edwards Exhibit 1001, p. 4
`
`Edwards Exhibit 1001, p. 4
`
`

`

`US. Patent
`
`Oct. 23, 2001
`
`Sheet 3 0f 4
`
`US 6,306,141 B1
`
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`
`Edwards Exhibit 1001, p. 5
`
`

`

`U.S. Patent
`
`0a. 23, 2001
`
`Sheet 4 014
`
`US 6,306,141 B1
`
`1 $102
`
`00000000000000 %
`
`2
`
`Edwards Exhibit 1001, p. 6
`
`

`

`US 6,306,141 B1
`
`1
`MEDICAL DEVICES INCORPORATING SIM
`ALLOY ELEMENTS
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation of application Ser. No.
`07/956,653 ?led on Oct. 2, 1992, Which is a divisional of
`application Ser. No. 07/682,243 ?led on Apr. 9, 1991, now
`US. Pat. No. 5,190,546, Which is a divisional of Ser. No.
`07/252,019 ?led on Sep. 27, 1988, now US. Pat. No.
`5,067,957, Which is a continuation of application Ser. No.
`07/177,817 ?led Mar. 30, 1988, noW abandoned; Which is a
`continuation of application Ser. No. 07/047,824 ?led May 8,
`1987, noW abandoned; Which is a continuation of applica
`tion Ser. No. 06/865,703 ?led May 21, 1986, now US. Pat.
`No. 4,665,906; Which is a continuation of application Ser.
`No. 06/541,852 ?led Oct. 14, 1983, noW abandoned.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`This invention relates to medical devices incorporating
`shape memory alloys, and to improvements therein.
`2. Introduction to the Invention
`Materials, both organic and metallic, capable of possess
`ing shape memory are Well knoWn. An article made of such
`materials can be deformed from an original, heat-stable
`con?guration to a second, heat-unstable con?guration. The
`article is said to have shape memory for the reason that, upon
`the application of heat alone, it can be caused to revert, or
`to attempt to revert, from its heat-unstable con?guration to
`its original, heat-stable con?guration, ie it “remembers” its
`original shape.
`Among metallic alloys, the ability to possess shape
`memory is a result of the fact that the alloy undergoes a
`reversible transformation from an austenitic state to a mar
`tensitic state With a change in temperature. This transfor
`mation is sometimes referred to as a thermoelastic marten
`sitic transformation. An article made from such an alloy, for
`example a holloW sleeve, is easily deformed from its original
`con?guration to a neW con?guration When cooled beloW the
`temperature at Which the alloy is transformed from the
`austenitic state to the martensitic state. The temperature at
`Which this transformation begins is usually referred to as MS
`and the temperature at Which it ?nishes Mf. When an article
`thus deformed is Warmed to the temperature at Which the
`
`
`alloy starts to revert back to austenite, referred to as A5 being the temperature at Which the reversion is complete)
`the deformed object Will begin to return to its original
`con?guration.
`Many shape memory alloys (SHAs) are knoWn to display
`stress-induced martensite (SIM). When an SMA sample
`exhibiting stress-induced martensite is stressed at a tempera
`ture above MS (so that the austenitic state is initially stable),
`but beloW M d (the maximum temperature at Which marten
`site formation can occur even under stress) it ?rst deforms
`elastically and then, at a critical stress, begins to transform
`by the formation of stress-induced martensite. Depending on
`Whether the temperature is above or beloW AS, the behavior
`When the deforming stress is released differs. If the tem
`perature is beloW AS, the stress-induced martensite is stable;
`but if the temperature is above AS, the martensite is unstable
`and transforms back to austenite, With the sample returning
`(or attempting to return) to its original shape. The effect is
`seen in almost all alloys Which exhibit a thermoelastic
`martensitic transformation, along With the shape memory
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`55
`
`60
`
`65
`
`2
`effect. HoWever, the extent of the temperature range over
`Which SIM is seen and the stress and strain ranges for the
`effect vary greatly With the alloy.
`In copending and commonly assigned US. Patent Appli
`cation (Docket No. MP0873-US1) to Quin now US. Pat.
`No. 4,505,767, the disclosure of Which is incorporated
`herein by reference, a nickel/titanium/vanadium alloy hav
`ing SIM over a Wide temperature range is disclosed.
`Shape memory alloys have found use in recent years in,
`for example, pipe couplings (such as are described in US.
`Pat. Nos. 4,035,007 and 4,198,081 to Harrison and Jervis),
`electrical connectors (such as are described in US. Pat. No.
`5 3,740,839 to Otte & Fischer), sWitches (such as are
`described in US. Pat. No. 4,205,293), actuators, etc.
`Various proposals have also been made to employ shape
`memory alloys in the medical ?eld. For example, US. Pat.
`No. 3,620,212 to Fannon et al. proposes the use of an SMA
`intrauterine contraceptive device, US. Pat. No. 3,786,806 to
`Johnson et al. proposes the use of an SMA bone plate, US.
`Pat. No. 3,890,977 to Wilson proposes the use of an SMA
`element to bend a catheter or cannula, etc.
`These medical SMA devices rely on the property of shape
`memory to achieve their desired effects. That is to say, they
`rely on the fact that When an SMA element is cooled to its
`martensitic state and is subsequently deformed, it Will retain
`its neW shape; but When it is Warmed to its austenitic state,
`the original shape Will be recovered.
`HoWever, the use of the shape memory effect in medical
`applications is attended With tWo principal disadvantages.
`First, it is dif?cult to control the transformation temperatures
`of shape memory alloys With accuracy as they are usually
`extremely composition-sensitive, although various, tech
`niques have been proposed (including the blending by
`poWder metallurgy of already-made alloys of differing trans
`formation temperatures: see US. Pat. No. 4,310,354 to.
`Fountain et al.). Second, in many shape memory alloys there
`is a large hysteresis as the alloy is transformed betWeen
`austenitic and martensitic states, so that reversing of the state
`of an SMA element may require a temperature excursion of
`several tens of degrees Celsius. The combination of these
`factors With the limitation that (a) it is inconvenient to have
`to engage in any temperature manipulation, and (b) human
`tissue cannot be heated or cooled beyond certain relatively
`narroW limits (approximately 0°—60° C. for short periods)
`Without suffering temporary or permanent damage is
`expected to limit the use that can be made of SMA medical
`devices. It Would thus be desirable to develop a Way in
`Which the advantageous property of shape memory alloys,
`ie their ability to return to an original shape after relatively
`substantial deformation, could be used in medical devices
`Without requiring the delicacy of alloying control and/or the
`temperature control of placement or removal needed by
`present shape memory alloy devices.
`
`DESCRIPTION OF THE INVENTION
`
`SUMMARY OF THE INVENTION
`
`I have discovered that if, in a medical device containing
`a shape memory alloy element Which uses the shape
`memory property of that alloy, an element Which shoWs the
`property of stress-induced martensite is used instead, an
`improved device results.
`Accordingly, this invention provides a medical device
`intended for use Within a mammalian body, or in such
`proximity to a mammalian body that the device is substan
`tially at body temperature, Which device comprises a shape
`
`Edwards Exhibit 1001, p. 7
`
`

`

`US 6,306,141 B1
`
`3
`memory alloy element, the improvement in Which comprises
`the substitution of an alloy element Which displays stress
`induced martensite at said body temperature for the shape
`memory alloy element.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIGS. 1 and 2 illustrate the stress-strain behavior of an
`alloy Which exhibits constant stress versus strain behavior
`due to stress-induced martensite.
`FIG. 3 is a side elevation vieW of a partial section of a
`catheter of the present invention in a stressed con?guration.
`FIG. 4 is a side elevation vieW of the catheter of FIG. 3
`in an unstressed con?guration.
`FIG. 5 is a tracheal catheter, Which is curved in its
`unstressed con?guration, partially straightened by a straight
`pin restraint.
`FIG. 6 shoWs an IUD formed at least partly from a
`pseudoelastic shape-memory alloy being restrained in a
`deformed shape by a restraining tube.
`FIG. 7 shoWs a guide catheter, transport catheter, and
`compacted Wire coil stent according to the present invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`10
`
`15
`
`20
`
`25
`
`The invention Will be discussed ?rst by introducing the
`concept of stress-induced martensite and the effect achiev
`able by its use, and then by eXamples shoWing hoW SIM
`alloy elements can be substituted for conventional SMA
`30
`elements in medical devices to achieve the bene?cial effect
`of the invention.
`The Figures illustrate the phenomenon of stress-induced
`martensite by means of stress-strain curves. In both FIG. 1
`and FIG. 2, the alloy is at a temperature betWeen MS and M d
`so that it is initially austenitic; and it Will be assumed for the
`purposes of this discussion that MS is equal to M], and AS
`equal to
`FIG. 1 shoWs the case When the temperature is
`beloW AS, so that any martensite formed by the applied stress
`is stable; While FIG. 2 shoWs the case Where the temperature
`is above AS, so that austenite is the only stable phase at Zero
`stress.
`In FIG. 1, When a stress is applied to the alloy, it deforms
`elastically along the line DA. At a critical applied stress, cM,
`the austenitic alloy begins to transform to (stress-induced)
`martensite. This transformation takes place at essentially
`constant stress until the alloy becomes fully martensitic at
`point B. From that point on, as further stress is applied, the
`martensite yields ?rst elastically and then plastically (only
`elastic deformation is shoWn at point C). When the stress is
`released, the martensite recovers elastically to point D, at
`Which there is Zero residual stress, but a non-Zero residual
`strain. Because the alloy is beloW AS“, the deformation is not
`recoverable until heating above AS results in a reversion to
`austenite. At that point, if the sample is unrestrained, the
`original shape Will be essentially completely recovered: if
`not, it Will be recovered to the eXtent permitted by the
`restraint. HoWever, if the material is then alloWed to re-cool
`to the original temperature at Which it Was deformed (or a
`temperature Where SIM behavior of this type is seen), the
`stress produced in the sample Will be constant regardless of
`the strain provided that the strain lies Within the “plateau”
`region of the stress-strain curve. That is, for a strain betWeen
`EB and EA, the stress Will be OM. This means that a knoWn,
`constant force (calculable from GM) can be applied over a
`Wide (up to 5% or more for certain Ni/T i alloys) strain range.
`Thus, though this resembles the conventional shape memory
`
`4
`effect, because the alloy shoWs SIM and is beloW AS a
`constant force can be achieved.
`In FIG. 2, When a stress is applied to the alloy, it deforms
`elastically along line DA, then by SIM along line AB, and
`by deformation of the martensite to point C, just as in FIG.
`1. HoWever, the stress-strain behavior on unloading is sig
`ni?cantly different, since the alloy is above AS and the stable
`phase is therefore austenite. As the stress is removed, the
`alloy recovers elastically from C to D then, at a critical
`stress, cA, the alloy reverts to austenite Without requiring a
`change in temperature. Thus reversion occurs at essentially
`constant stress. Finally if the stress is removed from the
`reverted austenite, it recovers elastically along line E0. The
`recoverable deformation associated With the formation and
`reversion of stress-induced martensite has been referred to
`as pseudoelasticity. While OM may be comparatively high,
`e.g. less than 50 ksi; cA is usually substantially loWer e. g.
`less than 10 kis; thereby creating a constant-force spring
`With an effective Working range of about 5% (cB—cA). The
`shape change available in the SMA is thus mechanically,
`rather than thermally, actuated and controlled, permitting a
`greater control over a device incorporating it.
`Suitable alloy for this invention ie those displaying
`stress-induced martensite at temperatures near mammalian
`body temperature (35°—40° C.), may be selected from
`knoWn SMAs by those of ordinary skill in theart, having
`regard to this disclosure by testing for the existence of the
`SIM effect at the desired temperature. A particularly pre
`ferred alloy is the nickel/titanium/vanadium allot of US.
`patent application Ser. No. 06/541,844 now US. Pat. No.
`4,505,767, referred to previously.
`The folloWing table sets forth transformation temperature
`data for disclosed in US. Pat. No. 4,505,767:
`
`TABLE
`
`Composition atomic percent
`
`Ni
`
`49.50
`50.00
`49.00
`50.00
`49.00
`50.50
`48.50
`50.00
`48.50
`49.00
`48.00
`48.50
`41.50
`46.50
`36.25
`49.50
`48.00
`47.75
`47.50
`48.50
`45.00
`47.50
`46.50
`
`Ti
`
`43.50
`44.00
`43.00
`45.00
`45.00
`48.00
`44.50
`46.00
`45.00
`45.50
`44.25
`45.50
`38.50
`43.50
`33.75
`46.00
`46.00
`45.75
`45.50
`46.50
`45.00
`46.50
`46.50
`
`V
`
`7.00
`6.00
`8.00
`5.00
`6.00
`1.50
`7.00
`4.00
`6.50
`5.50
`7.75
`6.00
`20.00
`10.00
`30.00
`4.50
`6.00
`6.50
`7.00
`5.00
`10.00
`6.00
`7.00
`
`MS
`
`A(90)
`
`—107
`—96
`—83
`—42
`—35
`—32
`—30
`—11
`—10
`—10
`—7
`—5
`—2
`—1
`0
`6
`12
`20
`26
`27
`30
`32
`34
`
`—88
`—84
`—61
`—33
`—12
`—6
`—13
`7
`15
`14
`8
`27
`86
`50
`42
`35
`36
`54
`58
`58
`71
`71
`70
`
`The A(90) temperature is the temperature at Which the transformation
`from the martensitic phase to the austenitic phase is 90% complete.
`
`The invention Will noW be discussed in detail by some
`EXamples of the use of an SIM alloy.
`
`EXAMPLE I
`
`Heart Valves
`Akins, in US. Pat. No. 4,233,690, the disclosure of Which
`is incorporated herein by reference, describes the use of a
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Edwards Exhibit 1001, p. 8
`
`

`

`US 6,306,141 B1
`
`5
`shape memory alloy ring to hold a sewing cuff to the body
`of an arti?cial heart valve. The ring is made in the austenstic
`phase, cooled to the martensitic phase, deformed, placed
`around the valve body, and heated or alloWed to Warm to
`cause reversion to the austenitic phase and recovery of the
`ring into engagement With the valve body.
`HoWever, this technique has not found commercial accep
`tance. Present medical technique requires that the valve
`body be capable of being rotated relative to the cuff, thereby
`enabling the surgeon to set the rotational orientation of the
`valve after it has been seWn into place. This is desirable
`because the techniques used make it dif?cult to visualiZe or
`accomplish optimal orientation during initial placement.
`In order to accomplish the desired torque control to permit
`the desired rotation and yet ensure a ?rm hold of the cuff on
`the valve body, precise control of the pressure exerted on the
`valve body by the ring is needed. This is dif?cult because
`there are substantial manufacturing tolerances in the valve
`body Which may be made, for example, of pyrolytic graphite
`or ceramics, etc. Because the austenite stress-strain curve is
`extremely steep, it is not considered practical to use the
`simple shape memory technique proposed by Akins. Indeed,
`Akins does not even address the. issue of rotation, of the cuff
`With respect to the valve body.
`HoWever, if an SIM alloy is used instead of conventional
`shape memory, the process may be considerably simpli?ed.
`First, if the alloy has a stress-strain curve like that of FIG.
`1, the alloy ring may be made just as for Akins. The ring is
`then expanded from its initial austenitic state by the forma
`tion of SIM. When the ring is placed about the valve body,
`it needs only to be heated above Af and alloWed to cool to
`its original temperature for the ring to engage the valve body
`6 constant force, even if he valve body has a deviation from
`the speci?ed siZe. The torque may thus be controlled to the
`desired level despite manufacturing tolerances.
`Second, if the alloy has a stress-strain curve like that of
`FIG. 2, the ring may be expanded, placed over the valve
`body, and the stress released all at the same temperature.
`Because the austenitic phase is stable, the stress-induced
`martensite spontaneously reverts to austenite until recovery
`is restrained by the ring engaging the valve body. Because
`the reversion to austenite takes place at constant stress, a
`constant force (and hence constant torque) may be obtained
`regardless of manufacturing tolerances. Close temperature
`control is not required, either; and the fact that the patient in
`a heart valve replacement operation is conventionally cooled
`as much as 15° C. or so beloW normal body temperature
`does not affect the operation of the ring.
`To control the torque at a suf?ciently loW level, it may be
`desirable for the alloy ring to be other than a solid ring, such
`as, for example, a continuous helical spring, a ?at ZigZag
`spring, etc. Such variations permit the achievement of a
`greater range of movement With constant force and a reduc
`tion in the force exerted by the ring on the value body, since
`the ring recovers in a bending,mode rather than in tension.
`
`EXAMPLE II.
`
`Catheters And Cannulas
`Wilson, in US. Pat. No. 3,890,977, the disclosure of
`Which is incorporated herein by reference, discloses a cath
`eter or cannula (both being included hereinafter in the Word
`“catheter”) made of,.or containing, an SMA element to cause
`all or a portion of the catheter to deploy in a useful form once
`introduced into a living body.
`HoWever, again this device has not been commercialiZed.
`Possible defects of the device Which have prevented com
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`55
`
`60
`
`65
`
`6
`the inability to sloWly emplace the
`mercialiZation include
`catheter in a desired position When the transition tempera
`ture of the alloy is beloW body temperature (since the SMA
`element Will attempt to revert to its original shape as it
`reaches body temperature), thus limiting the ability of the
`physician to place the device carefully and precisely; or
`alternatively, if the transition temperature of the alloy is
`above body temperature, the requirement that the device be
`heated to a temperature above body temperature to cause
`recovery and that the device be placed so as not to change
`shape again When it re-cools (since the body temperature is
`beloW the transition temperature); (ii) the inability to remove
`the device easily: and (iii) the need for controlled tempera
`ture storage to prevent premature reversion to austenite of
`the SMA, With consequent shape change.
`The issue of removal of a catheter is especially,
`signi?cant, and not addressed by Wilson. Consider, for
`example, a tracheal puncture catheter. This should be
`straight for easy insertion into the trachea through a puncture
`into the front of the neck, but should curve after insertion so
`that the How of air or oxygen through the catheter passes
`axially doWn the trachea rather than impinging on the
`surface of the trachea and damaging it. If a shape memory
`catheter is used as contemplated by Wilson, it Would pre
`sumably become austenitic and bend after insertion (see
`FIGS. 1a and 1b, and corresponding text, of Wilson). But
`removal Would require either cooling to beloW the transition
`temperature (Which could easily mean cooling to so loW a
`temperature that the tracheal tissue is damaged), removal in
`the bent shape (presumably damaging tissue), or forcing the
`austenitic SMA to straighten to permit direct removal
`(unlikely to be satisfactory since the austenitic alloys eg of
`Ni/Ti may have yield strengths of 100 ksi or more, and force
`suf?cient to cause plastic deformation Would be required).
`If an SIM element is used instead, hoWever, removal can
`be accomplished almost as easily as insertion. If the catheter
`is made in a bent shape (as in Wilson), it can be straightened
`by insertion of a straight pin doWn the catheter axis, the
`catheter deforming by the formation of stress-induced mar
`tensite. Insertion of the catheter into the trachea is accom
`plished While the catheter is straight, at Whatever rate is
`desired (permitting easy and accurate placement), and the
`pin is gradually WithdraWn to permit the catheter to take up
`its desired shape as the martensite reverts to austenite. [It is
`assumed here that the stress-strain curve of the alloy at the
`temperature of use is of the form of FIG. 2, so spontaneous
`reversion occurs on removal of the stress induced by the
`pin]. When removal is desired, it may be achieved simply by
`the gradual insertion of the pin, straightening the catheter
`and permitting easy WithdraWal. Insertion of the catheter
`into the body and pin removal may, of course, take place
`simultaneously if desired, as may pin reinsertion and
`removal of the catheter from the body.
`
`EXAMPLE III
`
`IUDS
`
`Fannon et al., in US. Pat. No. 3,620,212, the disclosure
`of Which is incorporated herein by reference, discloses an
`intrauterine contraceptive device (an IUD) proposed to be
`formed of a shape memory alloy. The device is suggested to
`be deformed in the martensitic phase (the transition tem
`perature being beloW the temperature of the uterus), and the
`deformed device insulated With, e.g., Wax and inserted.
`Removal is contemplated only by using tWo SMA elements
`in opposition, the higher temperature one being martensitic
`at body temperature but strong enough so that, if heated, it
`
`Edwards Exhibit 1001, p. 9
`
`

`

`US 6,306,141 B1
`
`7
`Will overcome the lower temperature element and deform
`the IUD back to a removable shape. The heating contem
`plated is electrical. The storage problem discussed in
`Example II also exists here, so that the device must be stored
`beloW its transition temperature.
`By the use of an SIM element, hoWever, these disadvan
`tages may be overcome. Again, assume that the alloy is SIM
`psuedoelastic, i.e. that it has the stress-strain curve of FIG.
`2. Then an IUD may be formed into the desired shape in the
`austenitic state, and deformed by compression into a tubular
`placement device (the deformation being such that the strain
`levels lie Within the “plateau” of the stress-strain curve).
`When the placement device is inserted into the uterus, the
`IUD may be deployed by extrusion of the IUD from the
`placement device. Deployment is then controlled but
`immediate, so that the physician may satisfy himself With
`placement. Removal is the reversal of placement: the place
`ment device is inserted into the uterus, the IUD deformed by
`WithdraWal into the placement device, and the placement
`device WithdraWn. Temperature control is not required.
`
`EXAMPLE IV
`
`Bone Plates
`
`Johnson et al., in US. Pat. No. 3,786,806, the disclosure
`of Which is incorporated herein by reference, propose the use
`of Ni/T i SMA bone plates in fracture ?xation. The plate is
`deformed in its martensitic state, screWed to the tWo ends of
`the bone it is desired to compress together, and Warmed (or
`alloWed to Warm) to the austenitic state, When the plate
`contracts, compressing the bone ends togethe