CA2101168A1 - Steerable cannula - Google Patents

Abstract

A device suitable for insertion into a mammalian body comprises an elongated tube (22) or cannula, an elastic member (24) for bending the cannula, and a straightener (26) preventing the elastic member (24) from bending the cannula. The straightener (26) and elastic member (24) are capable of relative axial movement, so that the straightener (26) can be positioned to prevent or allow the elastic from bending the cannula. preferably the elastic member (24) is formed from a superelastic shape-memory alloy. Other versions of the device without a straightener are described.

Description

_~ WO 92/14506 ~ -~ ~ ~ ~ ~ ~ PC'1'/US92/t)1135 ::;.y STEERABI.E CANNULA
The pfesem irnen>ion relates to a device for lrrsertipn ~o a mamma~an body.
Vila np catheters, stems, arrd the ike have many medical apps. These devices are usua4y passed Into and through a body orifice, irrdsion, peripheral artery. Win, or enital tract of a mamna~ran body a~ urWl thiay reach a desired organ.
shucture. or ~Y n the body.
These devices are available 1n marry forms and are used for a wide variety of p,ap~s, :.
6sbrrosbc and tnerapeuBC purposes. Among the uses of these devices are the insertion a ~ and medidnes into the body: stems such as for °r yes: endosoopes for .
vlewirrg what !e ~oin~ on in the body; sarrrpfarrD body ; d~ the oledricaf propeAies of ~ °~ ~ as the heart: passageways for inseAion of smaller a Khmers:
and therapeu8c techniques such as arpioplasfy.
A problem experienced with ~~ ~ ir~mn0 them Into the desired loth without d~aplnp body tissues or organs. A b be ar8i~pyy s~ that 8 can be ceded !mo '. Pas. yet at 1hs same time ~ eott ac as rat b taps or garret ~ ~y tire. For ~ple. hereon of a carwwla Mb a oororauy artery a the colon a~rars~nt ~ a l~uovs. beat paltr whh sensitive tip ~"0 ~ ~. and in the ctae a the vascular path, a path hating a !ergs number of brandy point:.
One such ~ of technique: haw been developed b a cs~ into a desired loce5on.
utuizes a guide wln carp an "~e,~ such as a wiro. The grdde win it used to negotiate a bent poraon of an orpsn, such as a blood veswl. in adva~ of the ttexble tube that !e b be Inserted. This ~ a >f,ne.oomu,Nnp and tedotrs p,.
Obrer devices have been detrobped u~,D ~,~..y alloys in a cannula. The shape of the shape-memp~r aaHp~, ~ g~ the coda i~ ~ h~ of the alloy. Such a device is shown in us. Patent No. 4,801,283. Other directed b of a ce~ria info a mamrraltan body through a tortuous path are dtbed in U.S. Patents Nos.
3.539'.034:
3.888.956: 3,890;977; 4,033,331; 4,427,000: 4,452,236: 4,885,908: 4,742,817;
and 4,926,860.
Many of these devices suffer from one or more disadvantages, in~np ex~;"e of the carrnula, complexity ~ operation such as a need to heat a shape-nrertrory alby, and ~ of a~ustedility over a wide range of cunrelures while~the tube is 1n a body drama!.
The Prestmt inverrdon is directed b an artiwde a devloe for inset:ion irrb a fan body that has none of these d~sedvama0es and has many desirable teahues, namely: .
.
sufficient steerabiHty that it can navigate tortuous, txanched paths through a marrrrrrailan body;
b. sufficient softness and flexibi~ty that tissue and organs are not damaged or traumatized:

WO 92/14506 , ;.-~~.~i~~~ .
c. ease of use, with no extemat heating required; and W ability to have the curvature adjusted over a largo rare even while the cannula is in a body channel.
The article oon~xiseS three main elements: 1 an eb . ~b ( ) ~~ ~ a ~~ia: (2) an elastic member for beading a hollow, , rat of the cannula: and (3) straigMenirrg or stOteninp means ~ p~~ ~ member from bendtrrg: The e~c member is cairabb of er>p~tnp the ~stal segment of the catmula without t~aay l~ the IMemal lumen (~ of the carrnula, The elaMic n~riber has two pene~ iorK. a bent shape and a ~Y ~pM shape. The r,~per is ~ alHf t0 tai the distal se~neM to bend when the elasUc member is hr its bent scrape. The sirener is capable of pthe ~ the df~al segrrrere of the annuls, b ~ ~~~ ~ ~ ion. the straigtrtermr and the member are of mlamrea~dal nrownwrw. Tire purpose of the move,nent is b the elastic tr>arr~rr from °n° 1o arrodwr for oomesporrd,>~y or ache dtetal of the bibs.
h a preterted vereipn ~ the lnvenfion, ~ ~r ~~ ~ member tram assumi ks bent shape, try rosulU~ tn the c~r~ ~ ~ and tbrear. When the ~
st~hbnsr is diserp~ from the. epic n. the e~tlc member bends and lheroby causes tfrfa distal sspmerrt of the card b bend.
fie ltrdudes an elo~rr~ wire or other means tx cep ardat ~~ bstweeft the etraipMener and the el:tsNc tr~rt~ ~ a~dal movement can be the nark of the a~ipht~rrer ~w b the elwWo nwnlber or vice versa. For e»rrple, the can be seourod b the carrKrle, wkh 1M atn~p~~ ~ r and on the outside o1 the anrufa, and t~ ~ be exbuded out of the stralpMener b a axwd oon~,~, ~ eye of P~erably the elastic nteniber is a Y SOY e~erk tom~ed at least paray from a shepe.nrerrary atby, and most preferably t~r~ at leant partly trap a Pseudoelastic. and most preferably, a superelastic ahape.memory ahoy that r,~,e stress-irrdu~d ~e at abort body t~mperature. As stress is app~ed to the alloy, the trrartensite oorrtent of the alby decreases (and the ~ dent deaeaaes), and as stress is mmoved iram the alby, the austenke content irrcxeases (and the martensite decreases). ~r o°~erroe. the bnrrer state is retemed 1o as the'etress-a<rduoed maAensltic state' and the tatter state is referred t0 a8 the ~ustenitk State". Norvever, It is unlikely that the alby i8 ever 100%
marterrsite in ha streas~rrdur~ marterrsific state or 1009~e austeNte in its austenitic state at ~oper,~ting temperatures.
The memory alloy element is in its beM shape when the alloy is In either its stress-induced marterrsidc state or austerrific state, and the memory alloy elemerri is substarnially strabM when the alloy is in its opposite state.

v~e0 92/14506 ~ ~ ~ ~ ~ ~ i'CT/US92101235 v . ~Xivi: . .
A particular advantage of using a superelastic shape-memory aAoy is that the elastic member can transtortn from one shape to another wlttiout any appicahon d heat.
A variety of physical ooMigurations are possible for this article. For example. the elastic member can be in the lumen of the raumrrla, e~iterior d the carurula, or bra into the visa of the c~r~la. A plurality d elastic members can be used. and the elastic member can be near. heGcai, zigzag. a tubular in shape.
The stratgMener can be tubular and around the peripheral wag d the la. or can be inside the as a rod a tube.. When the elastic member is tubular, the straigMener can be ir~ide the elas8c member. Wfren the atraigMerrer is h~u~r, the elastic member can be sized b fit inside rite straigMener. The elar$tic member can be incorporated Inb be peripheral wall d the The article can be used to a variety d appicMions. Fs e~cample. it can be used as an endosoope provided with rtle Lumens for the various elements d an endQSaope such as the ipM guide. 'W a article can be used as a stem or br iretertion d a >f rerapedic a aperu into a marnrnaAan body.
A device sooordfrp b the present inven~on has s~n~nt adveur~s. When the cannula t: » eodsnml n~rnber.1he device is su~erely soft and tlexble thd tie~re and organs aro not danapod at<aum:~ized Through the use d an ehtic nbrtiber. addent stear~tY i0 obtained that the device can nevlpete the brhrous and brandied petM bunts iMouptaw a ntamna0an body. Further, the device is easy to use, with a c~anpe in curvmurs d the distM aeqntartt d the camula being adaevrod merely by movlrp the sUa~htener or the elaa~c member. No exmmal heatinD ie roqu<rod. and by oontrotirp the amount d movement d the strilgMertsr or elesUc member. the bend d the clerics can be ac~usted over a hu~pe rarpe even wh~e the c~r~la is in a In another version d the Irrvetelon, the slraigMenar is tepiaoed wYh a abeasinp elerrrere, the st~np element being ettad>ad b an elastic~member made at least partly from a superelasttc shape.rnemory ahoy. TensioHrp the saessinp member results in the alloy being transfontred b contain more stress-induced martensite and the elastic member ass<aHng a substarxialhr straight shape. thereby substaMlally straightening the ~stal segment of the raarruta.
Release d the tension on the stressing member resins in trangtomnaUon d the alloy b contain more austen'rte and Itre elastic member trarrsfom~irp into a bent shape for herring the distal segment d the carurrrla.
l In arather device aoootdfng to the present invention, the purpose d the straigMener is r~eppcated by varying the diameter d the internal lumen d a canr>ula, a for exart>ple, by providng two canmrla of different ~ameters. The device has a c~stal segment provided with a lumen of a relal3vely large diameter, and an adjoirdng less distal segment with a kurren of relatively small dameter. An ebngated elastic member is provided inside the lumens and is axially sBdable in the lumens. The elastic member comprises twro segments connecled to each other at their distal ends.

t'CT/US92/01235 .:~,.;:' The elastic segments are bowed at their distal ends, such that they form a loop-like struGure, where the bop is substantially unstressed when it is completely inside the distal portion of the lumen. The unstressed loop is in a plane substantially parallel to the axis of the cauu~ula. When the loop is withdrawn irso the portion of the lumen which has a relatively smaN
diameter, the bowed portions of the elastic segments are stressed. The stress tends to cause the bowed portions to told together out of the plane paraael to the axis o! the canrKila. since the stress tends to create a berxiirrg stress at the connected tips of the segments. with some torsional stress in the fait parts of the segments.
8ecewse the bowed parts of the segments are forced info a folded oor>Hguration vrfiich is panera~r perper~arlar to the plane of the unstressed bop. the caurr~ula bends in a direction generaly perper>dicular to the original plane of the bop. Complete vritfrdrawal of the elesUc segments into the portion of the lumen which has a re~ivehr small detrreter leaves the dstal part of the cenrrrrla unsupported. which pemrits i< to be straight. and also soft and tlex~le.
the saaigtrtener can also be mt elastic rrrernber. For exeur~pie. two elongated. aotatable.
elastic a bending members can be placed in the kunen of a car~a, both elastic members actirp to bend the c~r>nda. By rotatirp one of the elastic nee to the other elastic members, the foroe exerted by the bendrp momeres of the elastic members on Ors a can be varied.
For eocarnple, if the bending moments aro opposite each other. no bendbp oocws (and thus one of the elsdlc members serves as the sroipf t. ~ the berx~rp moments aro in the same dredbn, maximum bending ooarrs.
A simNar etlect can be adrieved with a pwraity of elastb a bertdrp rnembea axially .spdabls in the cen~a. at least two of wMdr exert bending moments on the dstal segrrterrt of the carsxrfa in dBerent dredions. By axialy siring an elastic member into the dated segrtrent of the carr~a, it exerts a bending moment on the dstal segment. By siW p an addNortal elesdt: member into the dstal segment. the dr~ection a the bending of the dstal sepmen and tote artrowk of beridnp can be varied.
These and other features. aspects, and advantages of the present inver>Ibn will become better understood with reference to the followirp description, appended claims. and aooompanyirp drawings where:
Figure tA is a perspective view of an endosoope havirp features. of the present inventbn;
Figures 1 B and 1C are perspective views. partly in section. of the tip portion of the erxiosoope of F'p.1A, the lip portion beirp in a curved contiguratbn in Fig.1B
and in a straight oorrl'puratbn in Fig.1C:
Figures 2A and 2B are bngituc~nal seGional views of an end portbn of a carurrrla ~embodyirp features of the present inventbn, the carrots being in a straight oonfig<rratbn in Fp.
2A and in a curved configuration in Fig. 2B;
Figure 2C is a transverse sectbnal view of the canrx~la porfbn of Fig. 2A
taken abrp line 2G2C in Fg. 2A;

-awo 9m4so6 ~ ~ ~ ~ ~ ~ g iPCT/US92/01235 Figure 2D is a view similar to that of Fig. 2C of another version of a t~nnula having a muRip~ty of elastic members;
Figures 3A and 3B are brrgitudinal sectional views of the portbn of a second version of a carxwrla ert~bodying features of the present irnentbn, the end portbn being in a straight coon in Fig. 3A and in a arrved configuration in Fig. 38:
Figures 4A and 48 are longitudinal sectionaW iews d the end poAion of a third version of a carxrrrla embodying features of the present inversbn, the end portbn being in a straight oor~puragon in Frg. 4A and in a curved oor~igun~tion in Fig. 4B;
Figures 5A and 5B are bngihrdMal sec~onai views of the errd portion of a tourih versbn of a cannula embodying features of the present invention, the end portion being in a stmt oorrsprxation in Fig. 5A and in a coMguralbn in Fig. 58;
Figures 6A and fiB are brpidrdinal sectioned views of the end potion ~ a tidh version of a .
catxerta embodying features of the present inverrtbn, the end potion being in a straight oon~rguration in Fig. 6A and in a aged oorrfiguration in Fig. 88:
Fib 7A and 78 are bngidrdinal sactbtml views d the end poAbn of a ai>dh versbrt of a cola embodying fesbxes of the prosent invention, the end portion being M a straight oor~pura0on h Fig. 7A and in a curved oortligguratbn in Fig. 78:
Fipuros 8A ~d t3B aro bnpitudkral ae~ionrd views of the end portbn of a seventh version d s cau~a errrbodyfrrp >eeturos of the pnaerrt i<rverrtbn, the end porlbn being in a:tmtght corr~purabn In Fig. all and M a curved oonNpura<bn In Fig. 88:
Figuros 9A and 98 are bngidrdinal aedior>al views of the end poAbri of a eighth versbn of a c~anuls ertrbodyMp tesdures ~ the prosent hwentiorr,1he erd portion being in a straight oortAgu~ion in Flg. tifll and M a aurvsd aorrhgurrnbrt in Fig. 98;
Figures 10A and 1 OB aro brrgibrdlnal sectbnsl views d the end poAton of a n>rkh version of a eaustrrla enrbodyhrg teafuros of the proaeM kttverrdon, the end poAbn behrg in a sbatght oor~g~on in Fig.10A and in a curved con8guratbn in Rg.1 OB:
Firos 11 A and 11 B are brpidrdinal sac0onal views of the end potion of a tenth version of a carrrrula embodying features of the present bwersion, the end portbn being in a straight configuration In Fig.11A and in a curved ooMiguration in Fig.11 B:
Figures 12A-1 and 128~1 are partisal bngiludnal eec~ional views of the end portion of an eleventh versbn of a device embodying features of the present inventbn, the device having two joined superelasOc elements. with the s~ere~ic elements extendng out of a sma~
diameter Iwnen in Frg.12A-1, and partially withdrawn inb a smal aameter lumen in Fig.128-1;
Figures 12A~2 and 128-2 correspond to Figures 12A-1 and 138-1, respe~vely, the ~iiersion '2" Fires beirp side partial lor~tudlnal sedianal views:
Fire 13A schematiccally shows an end portbn of a twemh versbn of a device according to the present irnenGon where two rotatabie elastic members are in the lumen of a cannula:
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WO 92/14506 Pt'_T/US92/01235 Fgures 1313-13H show the net bending moments on the cannula of Fig.13A
resuking from rotating one of the elastic members relative to the other;
Figures 14A and 148 schematically show an end potion of a thirteenth device according to the present invention having four elastic members axiaby sidade h a ~uuu~la, and Figure 14C
schertwticaNy stows the net effective bending momera on the carrnula depending on which of the ehaskc members is engaging the distal portion of the canrxria: and Figures 15A,158, and 1x are schematic views showing a cen~xrla according b the present invention advancing beyond a branch point in a body fluid system.
M amide ZO having features of the preset>< hverfUon, as shown h Figuros 1A,1 B
and 1 C, comprises as hs main elements an eloped tube a canmda 22, an elastic member 24, and a atraipfkener or stklener 26. The 22 has at least one hterrral lumen 28. The epic nramber24 has a aibetaraiaky stratgM shape as shown h Fb.1C, and a bent shape as shown in FiD.1 B. The elastb member is wllidently stHf b cause a piable and bendadle dfatal set 30 of the canxrla to bend when the elastic member 24 is in ks beot shade. The atraier 26 is su(~enay sOtf to provsrrt the elastic member 24 and the cantWa 22 from bending when the ~sigl~er 26 is baled in the distal segrtwnt 30 of the carrtrrria 22.
The ~ 26 is moved axiaky wllhin the lumen 28 wkh a draw wht S2. P~inp the draw wee 32 bwanis the pro~dmal end 34 of tfie BAlde 20 to the positron shown h Figure 1 B
r~auks h ben~np ~ the distal sspmer>< of the . Pwlrirp on the draw wiro 32 to move the alraiptrsr 26 hb the distal segment 90 of the exrmula 22 stnupMens the ce~a so that it ass<anea the shape shown in Fip.1 C.
As described in detak below, aktrouph the deNoe 20 shown in Fb.1 is adapted b be used as an andoeoope, devices aooordNp b the present irrrenHon have many uaa and ins.
Such a daubs can be urea to substentiaky any appic~ion where s rxu~la Is axrontifr used ror .
bent of a nnutrnr, parfia~rhr htxnens. Fs example, such a device can be used for afe~ical morrkorhp, drairwpe, proasex~e readhp. Oas admron, hseNon of medication, irwertlon of dyes. wkhdrawal of tis~re a fluid samples, and htnoduclion of other devices such se arpioplasty cati~eters or forceps. The device can be used for a wide variety of body parts hduding the carrkovasarlar, urogenital. respiratory. lymph. and d~gestave systems.
Miong sped~c applications of a device according b the preserx hventbn ere use as an errdosoope as described in U.S. Patent No. 4,427,000; an hlraperitoneal catheter as described in t3em>arr Patent CF~147722A1: a suprapubic catheter a8 desaibed h Canadian Patent 1,001.034:
and a plasflc tube for sirxrsiHs con~tions as described in European Patent App~cakon 0129634.
App~ions for a dtvvice aoooniing to the present are not ~mited to medical 'appli~ons, but Mdude other app8catbns for indusMr and research, arch as viewitp orlrepairing difkCUk to reach bcadons. These include dangerous bcatiorrs such as fadpties contaminated with radiation.
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... ., WO 92/14506 ~ ~'r~ ~ 1 ~ ~ PCT/US92/01235 The present irnention will be described with reference to use of a cannula 22.
The term "cannula' incbrdes any ebngated. holbw tubular device, indudng catheters and slants. The canrxda can have a distal end that is either open or dosed.
The carnula 22 can be tom~ed from a wide variety d materials. It is generally a polymeric material such as polyethylene, polyvinyl chbride, polyester, polypropylene, polyamide, polyurethane. polystyrene. tkiorine ptastux and siGoone robber. or an elastomer or a composite rrrateria~ of the above-meraioned per. to thereby Corm a soft. smooth suAaoe with no irregldarhies thereon. In addtiOn, the cennula can comprise an ar~OO2~ulatinD
agent such as heparin and u<oidn~e, or a coalin~ of an arwiatuombus nmteAa( such as sifoorre rtrbber, a bbdc oopoHnrer of urethane and siioone ('Avootftans'~. a copolymer of hydroxyethyl nrethaaylate-styrons and the Ike. and can obtedn bw friction properles by use of resin haNnp a bw fridiorral srutaoe such as tluoro resin and through applyirp a krbric~rx audr as siloorre pl. wNremiore. an x-ray oorrt~t medium comprising a metal such as t3a, W. ~. t'b or the Ike. a a compound -therabelween can be mixed with the syMhsUc resin nfateAid tonNrp the cenmrla, so that the posliorr a the car~la in a vessel can be aoarrateiy detefntined r~oentgenopraphicaay witMn a ~y_ The atrail~I~ner 26, which serves as a rssha~np polar in f~0.1, can be Conned a most m~c n~riais such as stxgkal stainless steel. and most polyrrreric n. h can be formed of tha aarrte material as the car~la, but must have moro rigidly. such at; by bein2 wled with a filer, to r~esial the bendifp tome of the elastic member 24. Tris straigMener 28 cell be a separate element aaadred b the draw wire 32, or k can be a coating over a a tillrtp in the distal pall of the draw wire . 32.
Orwy a portteon of the strabMensr element 26 needs to have arllo>ant sUfhrsas and rigitdity to root the ber>dtng tome of the elaalc member 24. It is not necessary that the enlro straightener 26 be stilt. for example, the stralgMer>er can be a oolaur that is around the exbrior of the ca3uutula, with only the porlwr of the stredgMener proximate to the elastic member 24 formed of a stiff material. the rost of the streigMener can be as flexible as the carrnula.
The straightener can be essenlally any shape. such as a wire, rod. strip. or tt~lar. and can be ebrrgated or shoA. The minimal length of the straigMener is about the same as the length of the distal segment 301hat the straigMener is designed to prevent tram bendirp, ty~Cally from about t ~ about 50 cm in length.
The elastic member 24 is fomned from an elaslc material that ~pfays flexible.
resilent memory propeNes. The term'elasfjc material" is used herein to mean a material that has spring-ike properties, that is, n is capable of being deforrtted by an appied stress and then springing back, or 'recovedttg, to or toward its original unstressed shape or ooMiguration when the stress is rerraved.
The elastic material is preferably highly elasUc. The material for the elastac member can be polymeric or meta~c, or a combination of both. Such materials inchrde siWoone, polyvinyl resins (especially polyviny~hloride), polyethylene, resilienrt polyacetals, polyurethane, synthetic rubbers, .

WO X2/14506 ~ ~ ~~ ~ ~ ~ ~ PCT/US92/01235 teirafluoroethylene fluorocarbon polymer, sprang-tempered steel, and spring-tempered stainless steel. ' The use of metals, such as shape-memory alloys, for the elastic member is preferred.
Shape-rt~emory aibys that exhibit pseudoelastiaty, in particular superelasti~ty, are especially preferred.
U.S. Patent Plc. 4,935,068, which is commonly assigned with the present application and incorporated herein by reference, Beaches the fundamental principles of shape-memory albys.
Some alloys which are capable ~ transforming between martensitic and sustenihc shapes are able to exhbit shape-memory effect. The transformation between phases may be caused by a~change in temperatVre. For exarrrple, a shape-memory alby in the maRer>shic phase beans to tra~omy to the austenrtic phase when its temperature raises above As, and the transtorm'~tbn is complete when the temperature rises above Al. The forward transformation will begin when the temperature drops below Ms and is complete when the temperature drops bebw Mf. The temperatures Ms, Mf, As, and Af define the themnat transformation irysteresis loop of the shapeatremory alby.
Under certain oorx~ttorrs. shape-memory albys exhibit pgeudoelast~ty, which does riot rely on temperature change in order to accompBsh shape drarrge. A
pseudoelastic alby is capable of being ear deformed far beyond the elastic imits of coewer>tbttal rrretals.
The property of pseudoetasticity of certain shape-memory alloys, which preteraWy are used for the ~las~c member of this invention, is the s~jea of a paper er><itled "An Engineers Perapeaive of PseudoelastldtY, by T. W. Duerig and R. Zadno, publil shed in gg"~ggl6 page 380, T. W. Duerag, K. Meson, D. Stoeckel, and M. Wayman, eddors, t3utterworih Prrbpshers, 1990 (proceedings of a coherence entitled "Engineering Aspects of Shape Memory Aaoys", held in Lansing, Michigan in August 1988). As s~scussed in the paper, the drsdos<rr~e of which is trtoaporated herein by referer>ce, certain alloys are c~pabf~ of exhibiting pseudoety of two types: one type is superelastiaty, and the other type is near ps~ey.
°Superelasticity" arises in appropriately treated albys while they are in their austenitic phase at a temperature which is greater than As, and less than Nid (As, is the temperature at which, when a shape-memory alby in its martensi>ic phase is heated, the trar~fom>ation to the susterritic phase begins, and Md is the maximum temperature at which the trarrsfomiadon to the maetensitic phase can be irxiuced by the application of stress). Superelasiicity can be achieved when the ahoy is annealed at a temperature which is less than the temperahare at which the ahoy is fully reaystal6zed. Alternative methods of txeating superelasticity in shape-memory albys, such as so~tion treating and aging, or albying, are also discussed in the paper referenced befOrB ("An Engineers Perspective of Pseudoelasticitv"). An elastic member can be provided with a desired coM'~gufation by holding it in that configuration during annealing, or during so~tion treatment and aging. An elastic member formed from an alloy which exhibits superelasticity can be deformed substantially reversibly by 91% or more.

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.:.WO 92/14506 . PCT/US92/01235 In oornrast, "wnear pseudoelasticity" is believed not to be accompanied by a phase change (again discussed in the paper erniifed "An Engineers Perspective of Pseudoelastidty"). h is exhibited by shape-memory albys which have been cold worked or mated to stabilize the martensite. but have not been annealed in the manner discussed ai~ove. An elastic member tortrred from an ahoy exh~its inear pseudoelasudty can be deformed substar~ia~y reversibly by 4x a more. The treatment of shoe-memory abys to er~arxe their pseudoelastic properties is also ascussed in U.S: Patent No. 4,935.068 to Duerig, tire disdostue of which is ~oorporated herein by reference.
While the aby that is used in the e~ member 24 may exf~it either inear pseudoelastidty or superelasticihr. or pseudoelasticity of an intemrediate type. it is generally preferred that it exhibit superelasddty because of the Iarge a<raun<
detorrnadon that is available widrout the onset of plashdty. U.S. Patent No. 4.665.906 b Jervis. which is oorrrrarrly assigned wiM the present appncaniom and is incorporated herein by reference. leeches the use of , psekrdoelas:jc shape-memory abys in the medical devices.
The elesUc material is selected aooorW p b the dtaracterisNc~ desired of the amide. For , some appications where united elastic befravfor is acceptable IYor eocatmple.
less than 1.5x elastic delomratiortj, cortverwiorral spAng materials such as barttwn, steel, and beryt~m copper albys can , be suitable. Wlbrt a straps-mertiory afby is used. It is preferably a nickel Warrium based aby, which cstrt include addidoral ekrtrerris which migfn aflect 1hs ykW sasrrpth that is avai~bts from the ahoy a the temperature at which paNarlar deatrod pseudoslastic draracteristics aro obfeh>ad: For example. bs alloy can be a binary aby oortp e~nddly of Mdcel anki tun, fa example 50.8 sbmic peroent nickel and 492 atomic perosnt 0tan>um, a It may include a qtra~y of a third element such as copper. aoba~. vanadwrm, chromium. a iron. Abya oor~inp esssrttta~r of , nickel, own, and vanadiaxtt, atrdr as disclosed in U.S. Patent No. 4,505,767, ar preferred for sots applcationa, pamiarlamy since they can also exhib0 superslasac properly at a atormd body temperatures. and because they are stiller andlor can store more elasttc energy. Copper based abys.can also be used, for example. abys cor>sistirp essertdafly of copper.
akmtinum and Ndcef, copper. aluminum and zinc, and copper and zinc.
An elastic member exhibking ~perelasticity can be sk~tarsiaby rever~ltr detorrrred. by as much as eight percent or nave. Fs example. a t .00 meter length of superetastic wire can be stretched to t .t t meters in length, wherein the alby undergoes a phase charge b contain more stress-induced martensite. Upon release of the stress, the wire returns substanliaaay b its 1.00 meter length, and its alby o~nesponcngly returns b oontcn more austeNte. By way of cornrast. a , similar wire of spring steel or other oonvernional metal can only be etasticaNy stretched ~approximately one percent, or to 1.01 meter in length. Any lather stretching of the conventional wire, if not resulting in actual breccage of the wire, results in a non-elastic (plastic) trarrsfomration such that upon reset of the stress, the wire does not return to its original length. Linear - ~. r a s: ~. .
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~'~ ~/14~ ~ ~, ~ j ~ ~ ~ t'CT/US92/01235 pseudoelastic and superelastic materials can also be bent, twisted, and compressed, rather than stretched, to a far greater degree than any conven;ional metals.
It is believed that the superelastic property is achieved by phase transtortnation within the alby, rather than by the cGslocafwn movements which ocarr during the plastic deformation of or~nary metals. A superelastic material can be detomred and released ttrousarxis of times, w'tthout being subject to breakage due to the metal fat'~gue which imits the number of defom~ation cycles which an ordinary metal can undergo without failure.
As discussed in detail below with regard to the figures, the caruxila 22, the elastic or bendrp member 24, and the straighterrer 26 can be oriented in a wide variety of configurations.
The straightener can be inside or outside the cannula. or txria into the welt of the canrxrla. Similarly the e~stic member 24 can be inside or outside the canrwria, or embedded in the web of the carxrrrla. The elastic member 24 can be hoiow and the straightener can be sized to side irao the elastic member The straightener can be holbw and the elastic member can be sized to side into and out of the straightener.
The article 20 can k>dude more than one straigMerrer and more than one elastic member 24. t=or exempts. a plueaity of elongated elastic members can be embedded in or positioned the wall of the caruxtia, such as positioned eqrrelly spaced apart around the wati of the cau>nula. For example, if tour elastic members 24 are used, they can be spaced apart irnm each other at bout 900~ Akematively, a pkrraity of elastic members can be used and placed end~to-end rather than having a single ebnpated elastic member.
In addition the elastic members need rat be aeneraiy inear M configuration, but rather can be helical or in a ~Zaq' ooN~uration. The elastic members need not be parallel to each other, but rather can be twisted together as in a braid.
The amours of bend available from the elastic member can vary with each appication, but gerrera~r a bend of at lead about 200 is desired, with a maximum bend ~ about 1800 being sufficient for most prac~iCal appications.
The draw wire 32 can be formed from any t>turreer d materials, such as surgical stainless steel or piano wire, that is suffiaently strong to be able to pull on the element to be moved, i.e. the straigMerrer 26 or the elastic member 24, depending on the appication. In addition, prefentbly the draw wire is $ut(icierrtly sttit that is can be pushed in the opposite rtirection for restoring the element moved to its original position. This alk>ws repeated berxfirrg and urrberrcting of the c9stal segment 30 of the c~rmula 22.
When the elastic member 24 provided at the distal end portion 30 of the caru~ula 22 is at least partly formed of a superelastic shape-memory aioy, it has elastic strain characteristks capable ef being displaced to a comparatively high extera under mir>imal stress and is easily defortnable to a straight configuration. Shape-memory albys have a special feature which is beneficial for any of the embodiments of this invention. As a superelastic shape-memory alloy is increasingly deformed from 'rts unloaded shape, some of its austeivtic phase changes into 'tts stress-induced martensite S~ '. ,.
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This means that while the alloy undergoes this phase change, it can deform greatly with only minimal increases in bading.
Therefore, elastic members comprising superelastic shape-memory alloys have a hula-in safety feature. These elastic members can be designed such that when they are loaded beyond a certain amount, the elastic members tend to defomn with a concomitant austeNte phase to stress-induced martensite phase change, instead of merely presenting a greatef feSIStanCe with limited defom,ation to the bad, which is seen with oonvernional metals. .
Because supereiastic shape-memory albys are easily defomned, when the Nstal end portion 30 of the cannula 22 goes through a bent portion of a channel, such as a blood vessel, a high flexural defort~tbn value can be obtained under a comparatively low bad.
This snows the cannuia 22 to pass through channels M the mamrnasan body such as bbod vessels because the canrxria can be comparatively easily curved aooorrnng to vascular branding, and the cannula can be smoothly advat>ced to a predetemaned position. A torque can be appned to the carux~la to r~e~biy and readily deed the distal portion 30 toward a predeterrt>ir>ed posHbn in the path being traversed. so that insertbrt of the distal segment 30 to a designated positbn in 8 oompAr~ied system can be adieved.
With reference to Figs.1A,1 B and 1 C. when the aNde 20 is an endosoope. the cannula 22 is provided with mulnpte lumens. a lumen 28A for a fiberoptic element 36. a second lumen 28B
for the elasUc member 24, and a third lumen 2f3C for the draw wire 32 and stratgMerter 26. The proximal end of the device is provided with a handle 38 for holding the device 20 arxf torqufrtg the distal segment 30 of the cartnula. For instance. syringe-plunger mechanisms, alder medtaNsms.
sues adion medraNsms. and pistol grip medtar>isrr>s can be utWzed. Ban cue means 38 arse provided for moving the draw wire 32 back and foAh for correspondingly moving the a><aigmener 26 back and forth atdaay in the caramia 22, for corresportdin~ly benc~ng and unbending the distal segrnen< 30 of the c~nula. , in the drawings discussed below, when the same reference numbers are used as used in earner figures, the elements ar substar~ially the same and serve substantially the same furxxion, although there may be minor differences. ' In all of the ertiboNmen<s, preferably the elastic members are at least partly made of a superelastic shape-memory alby.
' In the version of the invention shown in Figs. 2A, 2B, and 2C, a cyBndrical, tubular external straightener 37 is provided exterior of the cannula 22. The straigMener 37 is ooncerttric with and coaxial with the cannula 22, and is sued so that relative axial movement is possible between the canrwla 22 and the straigMener 37. Within the lumen 28 of the cannuia 22 there is an elastics member 24. By pushing or extruding the cannula 22 out of the straigMener 37 (or aaematively pulling the straightener 37 out of the distal segrtient 30 of the cannula 22), the cannula and the elastic member are transfom~ed from the configuration in Fig. 2A to that of Fig. 2B, thereby r , 1 :, ' f ~ l 1 .

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w0 92/14506 ~ ~ ~ ~ ~ ~ $ PCT/IJS9Z/01235 achieving a awed configuration.. Reversal of this movement results in the cannuta reverting to its straight configuration as shown in Fig. 2A from the curved configuration of Fig. 2B.
As shown in Fig. 2D, a plurality of elastic members 24 can be used, and these elastic members can be embedded in the wall of the cannula 22. The elastic members 24 in Fig. 2D
extend parallel to the bngitudinai axis of the cannula 22 and optionally are equally spaced apart from each other around the diameter of the cannula, being about 900 apart from each other. An advantage of using more than one berxiing element 24 as shown in Fig. 2D is that more bending force can be achieved. particularly when the ber~ng elements 24 are oriented so that they all tend to bend in the same direction.
As shown in Figs. 2A and 2B, it is not necessary that the entire straightener element 37 be stiff. In the versbn of Fig. 2, the ac;tua! portion of the straigMener 37 that is slit( is oNy an end sefpneM 37A, since this is the only portion of the straigMener 37 that serves to prevent ben~ng.
The proximal portion 39 of the straigMener 37 is sutl~entiy flexible to be bent. In an aQemate version of tr»s embodiment. the tubular straigMener 37 is axiaAy sideble within the hrrtten 28.
In the versbn of the invention shown in Figs. 3A and 3B, a tubular hoibw straightener 40 is used and the straigMener is sized to slide over the elastic member 24 and ~
composed at least PAY ~ a superefasric shape-rnenary aNoY. Tt~s sidirp movemertt stresses the alby b>to a staue or phase oor>talNng more stressed-itx><x~d martensite in which state the elasUc member 24 is ~Y ~dOM. 8Y Pu~nD ~ a wire 32 in the directio<t shown by arrow 42 in Fig. 3A, the stralgMener 40 is puhed at least partly oft the elastic member 24 to the positbn shown In Fig. 38.
This resuds in the alloy trans:omting to its austenitic state or phase oontaiNrtg less martensite and more austeNte. in which state the memory aiby element is in its beM shape, thereby rosining in the distal segment 30 of the canr>ula 22 bending as shown in Fip. 3B. The amount the straightener 38 is moved in the direction shown by arrow 42 detemtines the arraunt of axveterre ad>ieved.
Pushirtg on the draw wire 32 in the direction shown by arrow 44 in Fig. 38 resuks in the strai~tener 38 sAding over the superelasstic shape-memory aNy elastic member 24. thereby irxxeasing the martensite content of the alloy, which serves to trarssfortn the device 20 into the configuration shown in Fig. 3A.
In the. version of the invention shown in Figs. 4A and 4B, the elastic member 46 is a holbw tube with a lumen 47 that is optionally capped. A straigMener or stressing member 48 is sized to fit within the lumen 47 of the elastic member 46. The elastic member 46 is at the distal segment 30 of the cadnula 22. SGc~ng the straigMener 48 out of the lumen 47 of the elastic member 46 in the direMion shown by arrow 42 results in the distal segment 30 of the cannula 22 bending as shown in Fig. 48. The amount that the straightener 48 is slid out of the lumen 47 controls the degree of curvature achieved. As shown in Fig. 4B, only partially withdrawing the straightener 48 results in a relatively small amount of curvature of the dGstal segmern 30. Complete withdrawal of the straightener 48 results in a greater amount ~of curvature.

CVO 92/14506 ~ t'CT/US92/01235 Sliding the straightener 48 back into the lumen 47 of the elastic member 46 in the direction shown by arrow 44 in Fg. 4B reverts the cannula 22 and the elastic member 46 to the substantially straight Bnear ooMiguration shown in Fig. 4A. This, is achieved by reversion of the superelastic shape-memory alby that Is used to at least partly form the elastic member 24 !o its stress-induced martensitic state from its sustenitic state.
In Figs. 5A and 5B, the cannula 22 is provided with a tubular, ebngated straigMener 50 having a lumen 51, the bngitudnal axis of the straigMener 50 being substantially paraNei to the br~yitud~nal axis of the cannula 22. The straightener 50 is positioned upstream ot, but proximate to the distal segment 30. An elasst;c member 52 is sized to fit within the lumen 51 of the straightener ' 50 and be stressed thereby, and is adapted to be sid axiaGy witt~n the lumen 28 of the la 22 ' ' and the lumen 51 of the stiffener 50 by being maneuvered with a haw wire 32.
The elastic member 52 is preferably fom~ed of a superelastic shape-merrmy alloy, the alby displaying reversible stress-induced martensite at about body temperature such that i< has a stress-lnduoed martensitic slate having relatively hare martensite phase and rela~vety less mratenite phase. The elas~c member is substarniaay straight h its constrained -induced martertsidlc state. and has the Grnred oonfiguratbn as shown in Fig. 58 when the cloy is in its wtoonstrained austeniHc state.
The distal segment 30 of the carttxrla 22 is transfom>ad from its straight ooNiguration of Fip. 5A b ks curved otx><iguratbn of Fig. 5B by siidingthe elaaUc member 52 in the ~reabn of arrow 44 in F1g SA out of the straightener 50 into the distal segrttertt 30 of the carrnula. The ~stal segment 30 Is straightened from the positbn shown in FIg. 5B to the strbitarriiaMy straight oor>~r~on of Fig. 5A by puling the elastic member 52 back into the stredgMener 50 in the directtort stawn by arrow 42 in Fig. 5B. This trar>slatrrs the alloy b I<s atress~induoed martenshlc state, in which the elastic member 52 is substar~ially St~dgM, and at the same time the straigMener 50 is auf~denHy stHt to overoome any bending nament present in the efasUc member 52.
The versbn shown in Figs. 5A and 58 is similar to the version shown in Figs.
3A and 3B. A
key c6fference is that in the version of Figs. 3A and 38, the slraigMener 40 is moved while the elastic member Is stationary relative to the cannula 22: in the versbn of Figs. 5A and 5B, the straigMener 50 is statbna~r relative to the cannula and the elastic member 52 moves.
The versions of the invention depicted in Figs. 6A, 6B, 7A and 78 are very similar to the version shown in Figs. 4A and 4B. A significant difference is the change in the cor>f'~guratbn of the elastic member. In the version shown in Figs. 4A and 4B, the elastic mentber 46 is a tube with a dosed end. In Fig. 6 the elastic member is in the shape of a generally right circular cylindrical helix member 60. In the version of Figs. 7A and 7B, the elastic member 61 is in the form of a "zigzag"
'oonfiguratbn. In both versions, the elastic member is substantially coaxial with the canr>ula 22.
in the version shown in Figs. 8A and 8B, a rod-like straigMener 64 is provided upstream of She distal portion 30 of the cannula 22, on the proximate side of the cGstal segment 30 within the lumen 28 of the cannula 22. An elastic member 66 is sized to slide over the straightener 64, the :h ;, .'f, f S' ' .r,r~ .
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WO 92/14506 ~ --1 ~ ~ ~ PCT/US92/01235 elastic member 66 being tubular and having a lumen 68 sized to accommodate the straightener 64.
The elastic member 66 can be pulled onto the straightener 64 and off the straightener 64 into the distal segment 30 of the cannula 22 with the draw wire 32. Thus the version of the invention shown in Fps. 8A and 88 is similar to me version of me invention shown in Fps.
4A and 4B. A
d~terenoe is that in the version of Fps. 4A and 48, me straightener 50 is a cy~ndrical tube with the elastic member 52 sWdable into the tube; in the version of Fps. 8A and 8B, the elastic member 66 is tubular white the straightener 64 is sized so mat tha straigMener 64 can srrde into me elastic member 66.
When me elastic member 66 is on me straigtrtener 64, the straightener 64 keeps the elastic member straight. thereby keeping the canrnrle 22 straight. 8y moving the elastiic merger 66 kr the drection of arrow 44 as shown in Fp. 8A into me distal segment 30.
me elastic member moves toward its urroorrstrained configuration. wherein the elastic member 68 bends and causes .
me distal segment 30 to xkewise bend, as shown in Fig. 88. The device 20 can be reverted to the original ooMiguration of Fig. 8A from that of Fig. 88 by sidirp the elastic member 88 back onto me s~htener 64 in me d~recNon shown by arrow 42 in the Fig. 8B.
in Fps. 5A and 8A, the stiffener and the elastic rtrertiber are both proximal to the distal segment 30 rather than being boated in the distal segment. this may be advantaDeous in certain ~. since the ca3irurula c~stal segment 30 by itself preferably is flexble and pant. so that when tire stiffener and the elas~c member are both prordnta! b me distal segmer~ 30, the s~nrttrla 22 has a relatively atraumatic lea~np distal segment 30.
In the versbn of the inventbn shown in Figs. 9A and 98, the cannula 22 has an ebrpated elastic n>ertrber 24 in its distal segment 30. The elastic member 24 is tom>ed at least paAly from a aupsrola~c shape-rtiemory aNoy~ The aAcy displays rriverebls stressanduoed mautensite at about body temperature such that a has a s~ess~induced martensitb state (oontairtirrp relativehr more ma<ter>site) and an austenitjc state (oor>tsdrtirp more austeNte). The eHastic member 24 is kr a srmstarsiaily straight shape when me alby is in its stressed-induced martenskic slate, and me elastic member is in a bent shape when the alloy is in its susterstic state.
The eNastic member, which is on the inside waU 70 of me cannula 22 and has a br>~ihxiinal axis parallel to the br>mhrdinal axis of me c~uuxrla. lndudes a short lever arm 74 extending radialiy inwardly at me distal end of the elaStiC member. SeCUrBd b the (ever arm 74 is me dfaW WIfB 32, whidl seNeS t0 the elaStIC
member 24. Tensioning of me draw wire 32 by pulling on it in me dredbn of arrow 42 in Fp. 9A
resuas in the alby of me elastic member 24 beirp trar>stomled to its stress-induced rttartertsitic state, with the result that me elastic member 24 is substarriiaNy strait as shown in Fp. 8A. This results in me ~stal segment of the cannula likewise being substantially straight.
Release of the tension on the draw wire 32 transforms the alloy of the elastic member 24 to its austenitic state, with me result mat the elastic member reverts to its bent shape, wtuch results in me distal segment 30 of the cannula 20 likewise becoming bent. This oonfiguratbn of the device Is shown in Fig. 9B. Because the alloy displays reversible stress-induced martens'tte behavior at ~~NUO 92/14506 ~ ~ ~ ~ ~ ~ ~ PC1'/US92/01235 about body temperature, attemately tensioning and releasing the draw wire 32 attemately straightens and bends the distal segment 30 of the cannula 22.
The versions of a device according to the present irnention shown in Fgs.10A/10B and 11A/118 are substantially the same in concept and operation as the device shown in Fig. 9AI9B. , , The only significant deference is the change in the ~onfigurat'ron of the elastic member in the distal segment 30 of the cannula. In the version shown in Figs. 9A and 9B, the elastic member 24 is a rod. In the version shown in Frgs.10A and 108, the elastic member is in the shape of a generally right drcular cyGndricai helix member 60 (as shown in Fig. 6j. In the version oP Frgs.11A and 11 B, ag~n the elastic member is M the form of a heix, but not right drcuiar cyindrical, but rather of a 'zigzag' cor~guration (as shown in Frg. >~. In both versions of Figs.10 and 11, the helix is substarsially coaxial with the cannula 22.
In the versions of the invention shown in Figs. 9,10, and 11, the elastic member is bent abng its bngitudnal axis in its unconstrained cor>figuration. However, in any of these versions, the elastic member can be straight along its lorrgiardin.' axis in Its urxxr>stredned oonHarraHon, and the draw wire 32 could be used to bend the elas8c member and thereby bend the dstal se~ent 30.
The device 20 shown in Fip.12 has an interttal lumen with a østal potion 84 of relatively large diameter and an ad'pining proxi<ned potion 86 of relaftvehr smaA
diameter: This is aooortip~ahed by providing a cannula 22, which has a lumen 28 of substa~a~y oor>star>t internal diameter, with a hoibw pkp 90 therein, the h0lbw pkp 90 hating a lumen 9101 ro~vey smaller diameter. The cannula 22 and the plug 91 are coaxial, with the pkrg 91 belrp located in the proximal portion 86 of the device 20. Rather than providng the device 20 as two separate elements, namely the cannula 22 and the php 90, a single integral structure can be used.
The distal potion 30 of the carutula 22 is sufRdeMly flexMle to be bent. An ebrpated elastic member 98 is sized to tit within the Lumen of the pkrg 90 and is boated therein, and is axially s~dable In the plug 90 into the open distal portion 30 of the cennula 22. The ebngated~elastic member 98 comprises two ebngated substantiaay parallel segments 98A oonneded to each other at their distal ends 99. Ifieferably the elastic member 98 is at least partly formed from a superelastic alloy displaying reversible stressed-induced martensite at about body temperature.
Figs.12A-1 and 12A-2 show curved ~stal ends 105 of the elastic segments 98A
forming a bop when they are out of the plug and are completely in the distal portion 84 of the lumen, and are front and side views, respectively. Figs.12B-1 and 128-2 show the curved parts 105 of the elastic segments 98A partially withdrawn into the proximal portion 86 of the lumen, and are front and side views, respedivety.
The elastic member 98 is stressed by being withdrawn into the proximal portion 86 in the 'erection indicated by arrow 42. The stress on the curved parts 105 is such that the segments 98A
tend to told at point 99~and twist axially in the lumen. In other words, the curved parts 105 collapse toward each other by folding out of plane, rather than bending toward each other exclusively in . < ' c S.t.
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WO 92/14506 ~ ~ ~ '~ ~ ~ ~ t'CT/US92/01235 their plane. Therefore, the distal portion 84 of the cannula 22 also bends.
The direction of bend can be controlled by making the curved parts 105 join s6gMly out of plane at point 99.
This version of the invention has the advantage that the entire canruria 22 can be flexible, since there is no need for a stiffener. Moving the elastic member 98 in the direction indicated by .
arrow 44 pemwts the elastic members to return toward their unconstrained substantially planar cor>f'rguration, which tends to return to the distal segment 84 toward it straight configuration.
Frg.13 slaws another device 110 embodying slightly ctfferent features of this invention.
Two elastic members 111 are housed in parallel lumens 28 of a c~r~la 22. The portions of elastic members 111 which are housed within the distal segment 30 of the caruwla are curved, but when the elastic members 111 are constrained within the lumens 28. they are positioned to tend to curve in opposite c~ret~ions. If the elastic members 111 are idersk~lly curved and of the same elastic material (preferably superelasdc snape-memory alloy). each applies a force opposite to the other, with !he net effect that they keep the distal segment 30 straight. However, because the lumens 28 pemn rotation of the elastic members 111 therein, then these elastic rrrernbers can be rotated . a in unison, ro bend the distal segment 30. In this manner, ttte distal segrrterrtt 30 can be bars in any desired d~redion without fuming the entire car>nuta 22, merely by rotating the elastic members. Furthemrore, no stitfetrer is needed so that the entire 22 is nela~ivety flexible.
Some patterns of bend, viewed dagra~y from the distal end a Cannula 22, tire shown in Figs.13B-131. Version 1 of each of Figs.138-131, i.e., Fip.13D-1, is a top sdremafac view of the device 110. with an arrow 119 showing the net effective direction of bending moment resukirp from the combined bending moment of the two elastic members 111.
Version 2 of each ttgure, i.e., Fig.13D-2, shows the direction of the bending moment exerted by each of the elastic members, which combined bending moment results in the berrdMg shown by anew 119. Thus in t=p.130, the distal segmer~ 3p bends to the right as seen in the view of Fig.13D, and as shown by arrow 119.
Ntemative variations of ttus version are available. For e~cample. rrare than rivo elastic members can be uti~zed. Also. elastic elements of fiitferer4 inherent eiastic~es and curvatures can be used. For ir~star~e, one of the elastic members 111 of Fig.13 can be replaced by two separate thinner andJor weaker elastic elemeras to inocrporate a bias to bend in a set direction into the device 110. .
Mother version of a steerable canrurla 130 is shown in Figure 14. In the embodment, multiple elastic members 132 are at the distal end 134 of the canrxrla 130, but not in the distal segment 136. tech of the elastic members 132 is curved in its unconstrained shape, but when stored within the cannula, as shown in Fig.14A, they are positioned such that they tend to curve in c~verging directions. When one of the elastic members is slid ctstally ir4o the distal segment 136, it causes the distal segment to curve in the direction of curvature of this elastic member, as shown in Frg:14B. Figure 14A arbitrarily shows four elastic members, but any number of elastic members greater than or equal to two could be used. When two or more elastic members are slid distally into J h..~.....1 :."2. J.V ~.
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Figure 14C schematically shows end-on views of the various dredions of curvature in the case of four elastic members, where + marks an elastic member which has been sGd astally irno the dstai segmern 136.' marks an elastic member which has not been sWd distally into distal segment 136, and the open arrow 137 shows the direction of curvature.
M aitemative version of the embodmern shown in t=rgure 14 can have mudiple elastic members abeady presets in the dstal segmern 132 of the cannula. Sliding one a more elastic members in a proximal drection out of the distal segment 136 would then permit the remaining elastic elements to bend the distal segment 136 in the same erection as the resukaM vector of all the forces in the remair~ng elastic members.
In the embodment of Fcg.14, the elastic members can be positioned such that their ~
concave surf~es face radiaby inward when they are not oortstrained, or they can be positioned such that their concave auAaoes face radially inward when they are not oor~traiined. Also. segment 138 can be reinforced so that no bending can occur in this segrner4 no matter how many elassuc elements have been moved to achieve curvature of distal segment 136.
lMth reference to Figs.15A,15B, and 15C, the device 20 in accordance with the version of the Irrierrdon shown in Fig. 2A is presented as navtgaUrtg a potion of a torluorrs path in a human body. A8 shown in Fig.15A, the device is substantially straight and has reached a branch in the path 172 where the device can either go through a first branch 174 or a second branch 176. To cause the device 20 to traverse the second txanch 176. the straightener 26 is caused to axially s8de proximately 1o uncover the distal segment 30 of the carutlrla 22, resuitirtg in the distal segment 30 bending toward the second txanch 176. as shown in Fig.158. Then the entire device can be pushed in the direction of the distal segment Into the second txarx;h 176, as shown in Fig.
15C. In contrast, if it is desired to erner the first branch 174, the entire device or the bending mechanism itsea can be rotated along its axis by 1800. The same sequence of witlxkawing the stiffener 20 to uncover the distal segment 30 to pem~it this segment to bend coward the first branch 174, and then advancing device 20 can then be carried out.
Most of the embodmern described so far for this invention onlyy permit bendng in one plane. H desired, more than one bendng mechanism (e.g., multiple elastic membedstraightener combinations) can be incorporated irno an.erxksoopic device or catheter ~
perrNt ber~ng in more than one plane. For example, referring to Fg. t , if straigMener 26 has strip shape, with the strip being in a plane which includes elastic member 24, then straightener 26 can be used to prevent elastic member 24 from bending distal segmern 30, but pemdts bending of d~stai segment 30 in a second plane differern from the first plane (which includes elastic member 24 and straightener 26). Therefore, a second mechanism (which includes a second straightener, a second draw wire, and a second elastic member) can be incorporated in a device which is in a ... .f.:.,:-: .~:. ~ ..-.:. ._ ; : ; . .
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Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the scope of the appended claims should not be invited. to the description of the preferred versions of the invent~n described above.

Claims (53)

What is claimed is:

1. An article of manufacture comprising:
(a) an elongated tube having an internal lumen, a peripheral wall, and including a hollow, bendable distal segment;
(b) an elastic member engaging the distal segment of the tube, the elastic member having (i) a bent shape and (ii) a substantially straight shape, the elastic member being sufficiently stiff to cause the distal segment to bend when the elastic member is in its bent shape;
and (c) straightening means capable of preventing the elastic member from bending;
wherein the straightening means and the elastic member are capable of relative axial movement and wherein such relative axial movement transforms the elastic member from one shape to another for correspondingly bending or unbending the distal segment of the tube.

2. The article of claim 1 wherein the elastic member is a memory alloy element formed at least partly from a superelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state containing relatively more martensite and an austentic state containing relatively more austenite, the memory alloy element being in its bent shape when the alloy is in its stress-induced martensitic state, and wherein the straightening means is capable of transforming the elastic member to and from its stress-induced martensitic state.

3. The article of claim 1 wherein the elastic member is a memory alloy element formed at least partly from a superelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austentic state, the memory alloy element being in its substantially straight shape when the alloy is in its stress-induced martensitic state, and wherein the straightening means is capable of transforming the elastic member to and from its stress-induced martensitic state.

4. The article of claim 1 in which the elastic member is inside the lumen of the tube.

5. The article of claim 4 in which the straightening means is tubular and around the elastic member.

6. The article of claim 1 wherein the elastic member is incorporated into the peripheral wall of the tube.

7. The article of claim 1, 2, or 6 comprising a plurality of elastic members extending axially.

8. The article of claim 7 in which the elastic members are substantially equally spaced apart around the periphery of the tube.

9. The article of claim 1 wherein the elastic member is tubular.

10. The article of claim 9 wherein the straightening means is sized to fit within the elastic member.

11. The article of claim 1 sized for insertion into a mammalian body.

12. The article of claim 11 wherein the tube has multiple lumens.

13. The article of claim 12 wherein the tube is adapted to be used as an endoscope.

14. The article of claim 11 wherein the tube is adapted for use as a stent.

15. The article of claim 11 wherein the tube is adapted for insertion of a therapeutic or a diagnostic agent into the mammalian body.

16. The article of claim 1 in which the stiffening means is within the lumen of the tube.

17. The article of claim 16 in which the straightening means is tubular, is concentric and coaxial with the tube, and is axially slidable relative to the tube.

18. The article of claim 1 or 17 in which the straightening means is exterior of the peripheral wall of the tube.

19. The article of claim 1 in which the elastic member directly contacts the tube.

20. The article of claim 1 in which the straightening means directly contacts the elastic tube.

21. The article of claim 1, 2, or 3 in which the elastic member transforms from one shape to another without application of heat.

22. The article of claim 1 in which the straightening means is incorporated into the wall of the tube.

23. A device suitable for insertion into a mammalian body comprising:
(a) a cannula having an internal lumen, a peripheral wall, and a hollow, bendable polymeric distal segment:
(b) an elongated elastic member inside the lumen of the cannula, the elastic member having a bent shape and a substantially linear shape, the elastic member being sufficiently stiff to cause the distal segment of the cannula to bend when the elastic member is in its bent shape, the distal segment of the cannula being sufficiently pliable that it can be straightened into a substantially straight shape:
(c) a straightener axially slidable in the lumen of the cannula, the straightener being sufficiently stiff that when located in the distal segment of the cannula the distal segment cannot be bent by the elastic member: and (d) sliding means for axially sliding the straightener to and from the distal segment of the cannula for corresponding unbending or bending the distal segment of the cannula.

24. The device of claim 22 wherein the elastic member is a memory alloy element formed at least partly from a superelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the memory alloy element being in its substantially straight shape when the alloy is in its stress-induced martensitic state, and wherein the straightening means is capable of transforming the elastic member to and from its stress-induced martensitic state without changing the temperature of the elastic member.

25. The device of claim 23 wherein the cannula comprises a plurality of lumens with the elastic member in one lumen and the straightener in another lumen.

26. The device of claim 23 wherein the means for axially sliding the straightener comprises a wire attached to the straightener and extending to a proximal end of the cannula.

27. The device of claim 23 including a fiberoptic light guide.

28. A device suitable for insertion into a mammalian body comprising:
(a) a cannula having an internal lumen, a peripheral wall, and a hollow, bendable distal segment:

(b) an elastic member engaging the distal segment of the cannula, the elastic member having a bent shape and being sufficiently stiff to cause the distal segment to bend when the elastic member is in its bent shape, the elastic member being capable of being deformed into a substantially straight shape;
(c) a tubular straightener sufficiently stiff to prevent the elastic member from bending the distal segment of the cannula when the straightener is proximate to the distal segment of the cannula; and (d) means for moving the straightener along the cannula between a first position proximate to the distal segment of the cannula and a second position remote from the distal segment of the cannula for correspondingly unbending or bending the distal segment of the cannula, the distal segment of the cannula being substantially straight when the straightener is in its first position and distal segment of the cannula being bent when the straightener is in its second position.

29. The device of claim 28 wherein the straightener is external of the cannula and slides along peripheral wall of the cannula.

30. The device of claim 28 wherein the straightener is inside the lumen of the cannula.

31. The device of claim 28 or 30 where in the elastic member is imbedded in the wall of the cannula.

32. The device of claim 28 wherein the straightener is within the lumen of the cannula and is tubular, the elastic member is within the straightener, and the straightener is axially slidable along the elastic member.

33. The device of claim 28 in which the elastic member is secured to the cannula and is not movable relative thereto.

34. The device of claim 30 wherein the elastic member is helical and the stiffener is inside the helix.

35. A device stable for insertion into a mammalian body comprising:
(a) a cannula having an internal lumen, a peripheral wall, and a hollow, bendable distal segment;
(b) a hollow tubular elastic member internal of the cannula and engaging the distal segment of the cannula, the elastic member having a bent shape and a substantially straight shape, the elastic member being sufficiently stiff to cause the distal segment of the cannula to generally conform to the shape of the elastic member;
(c) a straightener capable of being inserted into the elastic member, the straightener being sufficiently stiff to prevent the elastic member from bending the distal segment of the cannula when the straightener is inside the elastic member; and (d) means for moving the straightener inside the cannula from a first position inside the elastic member to a second position remote from the elastic member for transforming the distal segment of the cannula from a substantially straight shape when the straightener is in its first position to a bent shape when the straightener is in its second position.

36. The device of claim 35 in which the means for moving comprises a pull wire.

37. A device suitable for insertion into a mammalian body comprising (a) a cannula having an internal lumen, a peripheral wall, and a hollow, bendable distal segment;
(b) an elastic member inside the cannula and axially slidable therein between a first position proximate to the distal segment and a second position remote from the distal segment, the elastic member having a bent shape and being sufficiently stiff to cause the distal segment to bend when the elastic member is in its bent shape, the elastic member being capable of being deformed into a substantially straight shape;
(c) a tubular, substantially straight stiffener within the cannula, the straightener having an internal lumen sized to receive the elastic member, the straightener being located remote from the distal segment of the cannula and being sufficiently stiff to transform the elastic member to its substantially straight shape: and (d) means for moving the elastic member axially in the cannula between its first and second position, the elastic member in its first position bending the distal segment of the cannula and in it second position being within the straightener and thus substantially straight, thereby correspondingly bending and unbending the distal segment of the cannula.

38. A method for navigating a tortuous path comprising the steps of:
(a) selecting the article claimed in claim 1;
(b) inserting the article into the tortuous path, the distal segment of the tube being inserted first: and (c) causing relative axial movement between the straightening means and the elastic member for transforming the elastic member from one shape to another for correspondingly bending or unbending the distal segment of the tube.

39. The method of claim 38 wherein the tortuous path is in a mammalian body.

40. A method for navigating a tortuous path in a mammalian body comprising the steps of:
(a) selecting the device claimed in claim 23;
(b) inserting the device into the mammalian body, the distal segment of the cannula being inserted first; and the distal segment with the sliding means for bending and unbending the distal segment of the cannula.
(c) axial sliding the straightener to and from the distal segment with the sliding means for bending and unbending the distal segment of the cannula.

41. A method for navigating a tortuous path in a mammalian body comprising the steps of:
(a) selecting the device claimed in claim 28;
(b) inserting the device into the mammalian body, the distal segment of the cannula being inserted first: and (c) moving the straightener axially along the cannula between the first and second positions for bending and unbending the distal segment of the tube.

42. A method for navigating tortuous path in a mammalian body comprising the steps of:
(a) selecting the device claimed in claim 35;
(b) inserting the device into the mammalian body, the distal segment of the cannula being inserted first; and (c) moving the straightener from the first position to the second position for bending the distal segment of the tube.

43. A method for navigating a tortuous path in a mammalian body comprising the steps of:
(a) selecting the device claimed in claim 37;
(b) inserting the device into the mammalian body, the distal segment of the cannula being inserted first; and (c) moving the cannula from its first position to its second position for transforming the distal segment of the cannula to a bent shape.

44. A device suitable for insertion into a mammalian body comprising:
(a) a cannula having an internal lumen and a bendable distal segment;
(b) an elongated elastic member engaging the distal segment of the cannula, the elastic member being a memory alloy element formed at least partly from a superelastic shape.

memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such as it has a stress-induced martensitic state and austenitic state, the elastic member being sufficiently stiff to cause the distal segment to have a shape corresponding to the shape of the elastic member, the elastic member being in a substantially straight shape when the alloy is in its stressed-induced martensitic state and the elastic member being in a bent shape when the alloy is in its austenitic state; and (c) stressing means coupled to the elastic member, wherein tensioning the stressing means results in the alloy being transformed to its stress-induced martensitic state and the elastic member being in its substantially straight shape and the distal segment of the cannula being substantially straight, and release of the tension on the stressing means results in transformation of the alloy to its austenitic state and the elastic member being in its bent shape for bending the distal segment of the cannula.

45. The device of claim 43 wherein the elastic member is an elongated wire.

46. The device of claim 43 wherein the elastic member is a helical coil substantially coaxial with the cannula.

47. The device of claim 43 in which the elastic member has a zigzag shape along the longitudinal axis of the cannula.

48. A device comprising:
(a) a tube having an internal lumen and a bendable distal segment, the internal lumen comprising a distal portion of relatively large diameter and an adjoining portion of relatively small diameter;
(b) an elastic memory alloy member axially slidable in the lumen of the tube, the elastic member being formed at last partly from a superelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the memory alloy member being in a bent shape when the alloy is in its stress-induced martensitic state, the memory alloy member being substantially straight when the alloy is in its austenitic state, the memory alloy member being sufficiently stiff to cause the distal segment of the tube to conform to the shape of the memory alloy member, wherein the diameter of the distal portion of the lumen is sufficiently large that the alloy is in its austenitic state when the memory alloy member is in the distal portion of the lumen and thus the memory alloy member and the tube are substantially straight, and wherein the diameter of the adjoining portion of the lumen is sufficiently small that the alloy is in its stress-induced martensitic state when the memory alloy element is in the adjoining portion of the lumen, and thus the memory alloy member causes the distal segment of the tube to bend: and (c) means for moving the memory alloy member from the distal portion to the adjoining portion of the lumen for unbending or bending the distal segment of the cannula.

49. a bendable device comprising:
(a) an elongated hollow tube having an open distal segment and an internal lumen, the distal segment being sufficiently flexible to be bent; and (b) an elastic member sized to fit within the lumen of the tube and axially slidable in the tube and out of the open distal segment of the tube, the elastic member comprising two elongated substantially parallel segments forming a loop at the distal end of the elastic member, wherein the elastic member when constrained bends to assume a bent position as a result of one segment of the elastic member tending to bend in a first direction and the other of the elastic member tending to bend in a second direction different from the first direction, bending of the elastic member resulting in the distal segment of the tube bending.

50. The device of claim 49 wherein the elastic member is a memory alloy element formed at least partly from a superelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state containing relatively more martensite and an austenitic state containing relatively more austenite, the memory alloy element being in its bent shape when the alloy is in its stress-induced martensitic state.

51. An article comprising:
(a) a cannula having an internal lumen, and a hollow, bendable polymeric distal segment;
(b) a plurality of elongated bending members inside the lumen of the distal segment of the cannula, each bending member being capable of exerting a bending moment on the distal segment of the cannula, the distal segment of the cannula being sufficiently flexible that it can be bent by the bending members, and each bending member being rotatable along its longitudinal axis within the lumen to change the direction of the bending moment exerted by the bending members on the cannula; and (c) means for rotating one or more of the bending members for straightening and bending the distal segment of the cannula.

52. An article comprising:

(a) a cannula having an internal lumen, and a hollow, bendable distal segment;
(b) a plurality of elongated bending members inside the lumen of the cannula, each bending member being capable of exerting a bending moment on the cannula and the elongated members being moveable axially in the lumen into and out of the distal segment for changing the direction and force of the bending moment on the distal segment;
and (c) means for moving the bending members in the lumen into and out of the distal segment for bending and straightening the distal segment.

53. The article of claim 51 or 52 wherein at least one of the bending members is a memory alloy element formed at least partly from a superelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about human body temperature such that it has a stress-induced martensitic state containing relatively more martensite and an austenitic state containing relatively more austenite.