(12) Unlted States Patent
`(10) Patent N0.:
`US 6,306,141 B1
`
`Jervis
`(45) Date of Patent:
`Oct. 23, 2001
`
`U5006306141B1
`
`(54) MEDICAL DEVICES INCORPORATING SIM
`ALLOY ELEMENTS
`
`James E. Jervis, Atherton, CA (US)
`Inventor:
`(75)
`(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(1)) by 0 days
`'
`'
`'
`'
`
`(21) Appl. N0~I 03/483,291
`-
`.
`Flled‘
`
`(22)
`
`Jun' 7’ 1995
`Related US. Application Data
`
`(60) Continuation of application No. 07/956,653, filed on Oct. 2,
`1992, which is a division of application No. 07/682,243,
`filed on Apr. 9, 1991, now Pat. No. 5,190,546, which is a
`division of application No. 07/252,019, filed on Sep. 27,
`1988, now Pat. No. 5,067,957, which is a continuation of
`application No. 07/177,817, filed on Mar. 30, 1988, now
`abandoned, which is a continuation of application No.
`07/047,824, filed on May 8, 1987, now abandoned, which is
`a continuation of application No. 06/865,703, filed on May
`21, 1986, now Pat. No. 4,665,906, which is a continuation
`of apphcatlon No. 06/541,852, filed on Oct. 14, 1983, now
`abandoned.
`
`(51)
`
`Int. Cl.
`
`7
`
`..................................................... A6113 17/56
`
`3,605,725
`3,620,212
`3,729,008
`37;:39323
`,
`,
`3,786,806
`3,789,841
`3,857,391
`
`3,868,956
`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
`
`
`
`9/1971 Bentov ............................ 128/2.05 R
`11/1971 Fannon, Jr.
`128/130
`4/1973 BerkOVits ..
`128/418
`313;:
`2196 et a1~ ~
`~~~~~1223/263?
`1ne ............
`..
`1/1974 Johnsonet al.
`................. 128/92 YN
`2/1974 Antoshklw .......................... 128/2.05
`12/1974 Lerner ..........
`128/127
`
`3/1975 Alfidi et al.
`......................... 128/345
`6/1975 Lerner .................................. 128/127
`
`6/1975 Wllson ......
`604/281
`. 128/92 B
`2/1976 Mohr et al.
`
`6/1976 Murray ......
`. 128/92 B
`.. 128/2 M
`7/1977 Guss et al.
`7/1977 Harrison et al
`285/381
`
`7/1977 Andreasen ............................. 433/24
`
`3/1978 Heilman ................................. 29/173
`. 148/11.5 R
`4/1979 Clabburn ......
`
`4’170’990
`
`10/1979 Baumgart et al. """"""" 128/92 YN
`-
`-
`(LISt cont1nued on next page.)
`FOREIGN PATENT DOCUMENTS
`8301576
`5/1983 (AU) .
`3086384
`1/1985 (AU)
`'
`-
`-
`(LISt cont1nued 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. Cl.
`
`................................................................ 606/78
`
`(List continued on next page.)
`
`.
`(58) Fleld of Search ................................ 606/78, 60, 108,
`606/62, 68, 200’ 195, 198; 623/1
`References Cited
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`
`(56)
`
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`’
`’
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`
`10/1967 Chardack ............................. 128/418
`
`12/1968 EdeirdS ~~~~~~
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`. 128/418
`
`11/1970 Tafeen .............. 128/221
`........................ 148/115
`1/1971 Wang et al.
`
`Primary Examiner—Justine R. Yu
`.
`(74) Attorney, Agent, or Fer—Sheldon & Mak
`57
`ABSTRACT
`(
`)
`Medical devices which are currently proposed to use ele-
`ments made from shape memory alloys may be 1mproved by
`the use of stress—induced martengite 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
`
`
`
`
`
`
`
`—IllllllIII,IIIIIIIIIIIIIIIIIIIIII"
`
`9
`
`IIIIIIIIll,IIIIIIIIIIIIIIIIIIIIII
`VA\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
`
`
`
`O’IIIIIIIIIIIIIIIIIII/
`
`Lombard Exhibit 1001, p. 1
`
`Lombard Exhibit 1001, p. 1
`
`

`

`US 6,306,141 B1
`
`Page 2
`
`US. PATENT DOCUMENTS
`
`OTHER PUBLICATIONS
`
`............................. 3/1.5
`4/1980 Kaster et al.
`4,197,593
`4/1980 Hamson et a1:
`‘
`401980081
`5/1980 Melton et al.
`....................... 337/140
`4,205,293
`10/1980 Hawkins, Jr.
`..
`128/658
`4,230,123
`
`11/1980 Akins ............. 623/2
`4,233,690
`
`12/1981 Finney ...........
`128/349 R
`4,307,723
`1/1982 Fountain et al.
`..... 75/211
`4,310,354
`
`4/1983 Levitan ................................ 128/757
`4,378,811
`8/1983 Luther .................................. 604/159
`4,401,433
`10/1983 Schreck ..
`604/165
`4,411,655
`
`1/1984 Simon
`128/1 R
`4,425,908
`1/1984 Ueda ........................................ 128/6
`4,427,000
`6/1984 Utsugi
`...................................... 128/4
`4,452,236
`..
`4,485,805 * 12/1984 Foster, Jr.
`606/195
`
`4,485,816
`12/1984 Krumme
`128/334 R
`
`12/1984 Tanaka ............. 433/20
`1/1985 Gianturco
`128/1 R
`3/1985 Quin ...........
`148/402
`
`4/1985 Zibelin ................................. 128/319
`4/1985 Balko et al.
`......................... 128/1 R
`9/1985 McCoy ................. 604/95
`
`
`12/1985 Hodgson et a1.
`128/1 R
`......................... 60/528
`5/1986 Hosoda et al.
`7/1986 Chikama .................................. 128/4
`10/1986 Nicholson et al.
`128/360
`
`5/1987 Jervis .............................. 128/92 YN
`5/1990 Sakamoto et al.
`.
`3/1993 JCIVIS ..................................... 606/78
`12/1976 (CA)
`...................................... 128/93
`
`4,490,112
`4,494,531
`4,505,767
`4,509,517
`4,512,338
`4,543,090
`4,556,050
`4,586,335
`4,601,283
`4,616,656
`4,665,906
`4,925,445
`5,190,546
`1001034
`
`.............................. F16L/21/00
`
`............................... 128/92 YN
`
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`3225151A1
`1/1984 (DE) .
`102685
`5/1983 (EP) -
`0105669
`4/1984 (EP) -
`0129634
`1/1985 (EP) .
`0132344
`1 1985
`EP .
`0140621
`5l1985 (EP)
`.
`0145166
`6/1985 (EP) .
`8211061
`12/1983 (FR) .
`1600000
`10/1981 (GB)
`2106190
`4/1983 (GB) .
`2114005
`8/1983 (GB)
`56—28980
`7/1981 (JP) .
`57—10163
`2/1982 (JP) .
`57—75647
`5/1982 (JP) .
`57—95452
`6/1982 (JP).
`57—119744
`7/1982 (JP) .
`5825140
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`584234512:
`313::
`(111:)
`'
`44047
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`50951
`3/1983 (JP) .
`5841546
`3/1983 (JP).
`5844047
`3/1983 (JP) .
`533323;;
`313::
`311:;
`'
`6220827
`4/1984 (JP)
`5997115
`6/1984 (JP) .
`6045356
`3/1985 (JP)-
`6:22:32
`343:: 88
`940759
`11/1980 (SU) ................................ 128/92 YN
`850067
`7/1981 (SU)
`128/92 YN
`
`1110447
`8/1984 (SU)
`128/92 YN
`9/1984 (SU) ................................ 128/92 YN
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`
`Mazer, “Therapeutic Embolization 0f the Renal Artery With
`Gianturco Coils: Limitations and Technical Pitfalls,” Radi-
`01083}; 138237—46 (Jan. 1981).
`1’
`.
`.
`“
`Perkins, Shape Memory Effects inAlloys, Plenum Press,
`NY 1975- (PP- 29-59,Rodtlguezartlclemp- 59-8913h1m12u
`artlcle; PP~ 273-304, Perklns amda)
`Robinson, “Metallurgy; Extraordinary Alloys that Remem-
`ber their Past,” Science) vol. 191’ N0. 4230 (May, 1976)
`“
`.
`‘
`,
`platgnérl Elm Y0? cayonggvglthclhtat M33103? Alloy’
`a ma 5
`ngmeermg’
`(
`)
`C ‘ pp‘
`_
`‘
`Wasilewski, “The Effects of Applied Stress on the Marten-
`sitic Transformation in TiNi,”Metallurgical Transactions, 2:
`NOV. 1971, pp. 2973—2981.
`
`,,
`
`Wayman, “Some Applications of Shape—Memory Alloys,”
`Journal ofMetals Jun. 1980 pp 129_137
`.
`.
`.
`’
`.
`’
`’
`PhYSIk 1“ Unserer Z6110 19770 Ni 20 Verlag Chemle GmbH>
`56116 33> and transmmn thereOf
`Dotter, Charles T., Transluminal Expandable Nitinol Coil
`Stent Grafting: Preliminary Report, Radiology, vol. 147, pp.
`259—260.
`
`.
`_
`cragg’ et al”RadmlOgy’“(Apr’ 1983) V01’ 147’ pl: 261 2%
`50116th, L MCDOHald, Shape Memory Alloys ,SClemlfiC
`America) Nov. 1979, pp 74-82
`Buehler’ et al., “SS—Nitinol Unique Wire Alloy with a
`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 Nickel—Ti-
`tanium and Observations on its A lication in the Field of
`.
`.
`pp
`.
`.
`Medic1ne”, 1979 (Reference 2 from Opposition).
`Bennsmann, et al., “Osteosynthesis Staples Made of Nick-
`el—Titanium, Manufacture Preliminary Experiments and
`Clinical Use Thereof” 1982 (Ref #3 from Opposition)
`“
`.
`.
`Baumgart, et al., Mechanical Problems in the Use of the
`Memory Effect for Osteosynthesis Plates , 1977 (Ref. #4
`from OPPOSMO“)
`Suzuki, Yuchi, Shape Memory and Super—Elasticity Effects
`in Ni—Ti Alloys. (Translation provided).
`Kirk—Othmer, Encyclopedia of Chemical Technology, 3rd
`Ed. vol. 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).
`Watanabe, Studies on New Superelastic Ni—Ti Orthodontic
`Wire, J. Jap. Soc. for Dental Apparatus & Mat’ls., vol. 23,
`N0 61, PR 47-57 (1981)
`Oonishi, Clinical Magazine: Orthopaedic Surgery, 32, p.
`011010010-
`Sullivan Variable Stiffening Device for C010HSCOpy, 0013-
`trointestinal Endoscopy, vol. 36 No. 6, pp. 642—643 (1990).
`
`* cited by examiner
`
`Lombard Exhibit 1001, p. 2
`
`Lombard Exhibit 1001, p. 2
`
`

`

`US. Patent
`
`Oct. 23, 2001
`
`Sheet 1 014
`
`US 6,306,141 B1
`
`STRESS
`
`
`
`C S
`
`TRAIN (8)
`
`STRESS
`
`[12.
`
`Lombard Exhibit 1001, p. 3
`
`Lombard Exhibit 1001, p. 3
`
`

`

`US. Patent
`
`Oct. 23, 2001
`
`Sheet 2 014
`
`US 6,306,141 B1
`
`[2.3
`
`
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`Lombard Exhibit 1001, p. 4
`
`Lombard Exhibit 1001, p. 4
`
`

`

`US. Patent
`
`Oct. 23, 2001
`
`Sheet 3 014
`
`US 6,306,141 B1
`
`
`
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`Lombard Exhibit 1001, p. 5
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`Lombard Exhibit 1001, p. 5
`
`

`

`US. Patent
`
`Oct. 23, 2001
`
`Sheet 4 0f 4
`
`US 6,306,141 B1
`
`w1.g..¢.....
`
`102
`
`03
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`Lombard Exhibit 1001, p. 6
`
`Lombard 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 filed on Oct. 2, 1992, which is a divisional of
`application Ser. No. 07/682,243 filed on Apr. 9, 1991, now
`US. Pat. No. 5,190,546, which is a divisional of Ser. No.
`07/252,019 filed on Sep. 27, 1988, now US. Pat. No.
`5,067,957, which is a continuation of application Ser. No.
`07/177,817 filed Mar. 30, 1988, now abandoned; which is a
`continuation of application Ser. No. 07/047,824 filed May 8,
`1987, now abandoned; which is a continuation of applica-
`tion Ser. No. 06/865,703 filed May 21, 1986, now US. Pat.
`No. 4,665,906; which is a continuation of application Ser.
`No. 06/541,852 filed Oct. 14, 1983, now abandoned.
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`5
`
`10
`
`15
`
`20
`
`This invention relates to medical devices incorporating
`shape memory alloys, and to improvements therein.
`
`25
`
`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
`configuration to a second, heat-unstable configuration. The
`article is said to have shape memory for the reason that, upon 30
`the application of heat alone, it can be caused to revert, or
`to attempt to revert, from its heat-unstable configuration to
`its original, heat-stable configuration, i.e. it “remembers” its
`original shape.
`the ability to possess shape 35
`Among metallic alloys,
`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 40
`example a hollow sleeve, is easily deformed from its original
`configuration to a new configuration 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 45
`and the temperature at which it finishes M]. When an article
`thus deformed is warmed to the temperature at which the
`alloy starts to revert back to austenite, referred to as A5 (Af
`being the temperature at which the reversion is complete)
`the deformed object will begin to return to its original 50
`configuration.
`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 M5 (so that the austenitic state is initially stable), 55
`but below Md (the maximum temperature at which marten-
`site formation can occur even under stress) it first 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 60
`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 65
`seen in almost all alloys which exhibit a thermoelastic
`martensitic transformation, along with the shape memory
`
`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 field. 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 difficult 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,
`i.e. 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
`
`Lombard Exhibit 1001, p. 7
`
`Lombard 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 configuration.
`FIG. 4 is a side elevation view of the catheter of FIG. 3
`
`in an unstressed configuration.
`FIG. 5 is a tracheal catheter, which is curved in its
`unstressed configuration, partially straightened by a straight
`pin restraint.
`least partly from a
`FIG. 6 shows an IUD formed at
`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
`
`The invention will be discussed first 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
`elements in medical devices to achieve the beneficial 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 M5 and Md
`so that it is initially austenitic; and it will be assumed for the
`purposes of this discussion that MS is equal to M], and A5
`equal to Af. 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 first 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 0M. This means that a known,
`constant force (calculable from 0M) can be applied over a
`wide (up to 5% or more for certain Ni/Ti alloys) strain range.
`Thus, though this resembles the conventional shape memory
`
`10
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`15
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`20
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`25
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`30
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`35
`
`40
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`45
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`50
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`55
`
`60
`
`65
`
`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-
`nificantly 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 0M 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 i.e.
`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
`£ 9.50
`50.00
`£ 9.00
`50.00
`£ 9.00
`50.50
`£ 8.50
`50.00
`£8.50
`£9.00
`£ 8.00
`£ 8.50
`£ 1.50
`£ 6.50
`36.25
`£ 9.50
`£ 8.00
`£ 7.75
`£ 7.50
`£8.50
`£5.00
`£ 7.50
`£ 6.50
`
`
`
`Ti
`£3.50
`£4.00
`£3.00
`£5.00
`£5.00
`£8.00
`£4.50
`£ 6.00
`£5.00
`£5.50
`£4.25
`£5.50
`38.50
`£3.50
`33.75
`£ 6.00
`£ 6.00
`£5.75
`£5.50
`£6.50
`£5.00
`£ 6.50
`£ 6.50
`
`
`
`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
`—107
`—96
`—83
`—42
`—35
`—32
`—30
`—11
`—10
`—10
`—7
`—5
`—2
`—1
`0
`6
`12
`20
`26
`27
`30
`32
`34
`
`A(90)
`—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
`
`Lombard Exhibit 1001, p. 8
`
`Lombard Exhibit 1001, p. 8
`
`

`

`US 6,306,141 B1
`
`5
`shape memory alloy ring to hold a sewing cuff to the body
`of an artificial 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 difficult 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 firm 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 difficult 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 simplified.
`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 specified 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 sufficiently 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 flat 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
`
`the disclosure of
`in US. Pat. No. 3,890,977,
`Wilson,
`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-
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`
`mercialization include (i) the inability to slowly emplace the
`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,
`significant, 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 flow 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 e.g. of
`Ni/Ti may have yield strengths of 100 ksi or more, and force
`sufficient 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
`
`Lombard Exhibit 1001, p. 9
`
`Lombard 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/Ti SMA bone plates in fracture fixation. 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 together. The Johnson
`et al. bone plate is of generally oblong configuration, over-
`laps a bone fracture and is secured by two screws to one
`portion of the bone and by two other screws to the other
`portion of the bone.
`Because of the high elastic moduli of the austenitic shape
`memory alloys, it will be difficult to c