CA2290990A1

CA2290990A1 - Radially expandable intraluminal stent and delivery catheter therefor

Info

Publication number: CA2290990A1
Application number: CA002290990A
Authority: CA
Inventors: Ronald J. Solar
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-06-19
Filing date: 1998-06-19
Publication date: 1998-12-23
Also published as: JP2002505608A; EP0989877A1; WO1998057692A1; US6004328A

Abstract

The present invention is a delivery catheter (10) for a radially expandable intraluminal stent (12). The delivery catheter comprises an elongate outer tube (14) defining proximal, distal ends, and a lumen (20) extending longitudinally therethrough. In addition to the outer tube the delivery catheter includes an elongate inner tube (24) defining proximal, distal ends, and a guide wire lumen (30) extending longitudinally therethrough. The inner tube is movably disposed within the lumen of the outer tube. The delivery catheter further includes a flexible deployment sleeve (40) having a first end attached to the distal end of the outer tube, and a second end attached to the inner tube at a location proximal to the distal end thereof. The pressurization of the lumen of the outer tube with a fluid causes fluid pressure to be exerted on the sleeve in a manner facilitating the movement, and the inner and outer tubes relative to each other such that a distal portion of the inner tube extending distally from the second end of the sleeve is deployed from the distal end of the outer tube.

Description

2 1 PCT/US98/12822 RADIALLY EXPANDABLE INTRALUMINAL STENT
AND DELIVERY CATHETER THEREFOR
Fi~ld of the Invent The present invention pertains generally to medical devices, and more particularly to a radialiy expandable intralu:-~inal stem device . and delivery catheter therefore.
Background of the Invention The term "ster.t" is generally used tc cesc=ibe endeprost::etic medical devices which are -i-~p~_anted in anatomical passaceways (e.g., blood ~ressels, gastrointestinal tract, genitourinary tract, endocrine ducts, etc...) of the body for the purpose of maintaining the patency or state of dilation of the passageway, reinforcing the passageway, or anchoring a tub::_ar graft or ether object within the passageway.
yn many applications, such stents are implanted in blood vessels to maintain dilation and patency cf an occluded region of blood vessel, or to '.~_old __. place a _::bu_a= e. ~~c't~:ina-~ graft which forms a cond::_~ th ro;:.;h a ;vea:~cened or ane,.:rys.;,-c S°_gmen t Of a bloo~ vessel.
Typica= ncn-vascular applications oz sLCn ster_ts are for dilatin ~ and maintainir_g patency of cons t=icted or ~stenot=c regions of tre gastrointestinal tract (e.g., esopzagus) , ducts of the bi? iary tree (e.g. , common ;bile duct) ~r anatomical passageways of the genitourinary tract (e. g., ureter, urethra fallopian tube, etc.).
Translu.-~inally impiantable stems are typically of radialiy expandable construction such that they may be

3 5 ini tialiy disposed in a compac t conf iguratio.~. of relatively small diameter upon or within a delivery catheter to facilitate insertion and transluminal advancement of the stent into the desired anatomical passageway. Thereafter, such scents are ~adially expar_ded to an expanded cor_figuration having a larger diameter which is equal to or slightly larger than the diameter of the anatomical passageway in which the scent is implanted. When radialiy expanded to such larger diameter, the stent will typically become released or separated from the delivery catheter, and will become attached or fractionally engaged to the surrounding wall of the anatomical passageway.
Some stems are combined or associated with a pliable, continuous tabular covering, in which case they are typically referred co as a "scented graft" or "stent graf t" .
_-- general, these incraiuminal apparatus .e., s terns , s tented graf is , etc. ) fal l in to two T.aj or categor=es -- a) self-°_xpanding and b) pressure expandabla. 'hose of the self-expanding variety ::~:ay be ormea cf resilient or shape memory ~«aterial (e. g., sprig steel er nitinolTM) which is capable o= seif exnaxding from its first (radially compact) diameter to its second (operative) diameter without the exert-on of outwara-.~y-directed force against the scent or scented graft. Examrles or such self-expanding scents and s ten red gr of is are set forth i~_ United S to tes Pater_ ~ Nos .

4,655, 77i (s~'allsten, e= al); 4,954,126 (Waliscen);
~,061,2~5 (Wailscen, e'~ al); 4,580,568 (Giant~rco);
4,83G,OC3 (Wo1=, et al); 5,035,706 (Gianturco, e~ al);

5,336,400 (Sons) and 5,354,308 (Simon, et ai) and Foreign Patent Publication Nos. W094\12136; W092\0673 ,and EPA183372. T'~ose of the pressure-expandable (i~.e., "passive expandable") variety may be formed of plasmically deformable material (e. g., stainless steel) which is initially formed in its first (radially compact) diameter and remains stable in such first diameter until such ti~~e outwardly directed pressure is exerted upon the scent or stented graft to ca::se radial expansion and resultant plastic deformation of the stent or scented graf t, to its second (dperative) diameter . Examples of such pressure-expandabl a stems and scented graf is are set forth in united States Patent Nos.5,135,536 (Hillsteaa); 5,161,547 (Tower); 5,292,331 (Boneau);
5,304,200 (Spaulding); 4,733,665 (Palmaz); 5,282,823 (Schwartz, et al); 4,776,337 (Palmaz); and 5,403,341 (Sofa=) and =oreigr_ Patent Publication Nos. EPA480667;
and W095\08966.
In many applications, careful positioning and sound anchoring of the stem or stented graft is critica l to the s~.:ccessful treatment of the underlying medical problem. In t:~is regard, the delivery catheter which is utilized to insert and position the stmt or stented graft :ay be an important aspect of the overall system.
Various types of delivery catheters for stems and stented grayts have been previously known, -ncluding those described in Jnited States Patent Nos. 4,665,918 (Garza, et al); 4,733,665 (Palmaz); 4,739,762 (Pal~:,az);
4,762,125 (Leiman, et al);,776,337 (Palmaz); 4,838,259 (Robinson, et al); 4,994,071 (MacGregor); 5,037,427 (Harada, et ai); 5,089,005 (Harada); 5,102,417 (Palmaz);
5,108,416 (Ryan, et al); 5,241,498 (Christian); 5,181,920 (Mueller, et al); 5,195,984 (Schatz); 5,201,901 (Harada, et al); 5,269,763 (Boehmer, et al); 5,275,622 (Lazarus, et al); 5,290,295 (~uerals, et al); 5,306,294 (Winston, et al); x,318,588 (HOrzewski, et al); 5,344,425 (Lau, et al); 5,350,30'3 (Goose, et al); 5,360,401 (Turnland);
5,391,172 (williams, et al); 5,397,345 (Lazarus);
5,405,380 (Gianotti, et al); 5,443,452 (Hart, et al);
5,453,090 (Martinez, et al); 5,456,284 (Ryan, et al);' and 5,455,59-4 (Marin, et ai) and Foreign Patent Publication Nos. LP-0308-815-A2; LP-0335-341-A1; EP-364-787-A; EP-0442-557-A2; EP-482976-A; EP-0505-686-A1; EP-0611-556-A1;
EP-0638-290-Ai; W094\15549; W095\01761; GB2196-857-A;
DE3042-229; and DE3737-121-A.
None ef~ the previously-known delivery catheter systems have been clearly optimal for a~l_ types of scents and stentegrafts. Accordingly, there remains a need in the art nor a design and development of improved delivery catheter systems for at least some types of stents and s tented gr of is .
Summarv of the Invention In accordance with the present i:wention, there is provided a delivery catheter for transluminally deliverir_g a radiaily expandable intralu~;~inal apparatus (e. g., a stent, scented graft, etc.) to a desired location within a body lumen (e. g., a blood vessel, gastro-intestinal tract, duct, urethra, fallopian. tube, etc.). ~he delivery catheter generally comprises an:

n some e:~:~odi~:°~.rs, the outer tube of the del ivery catheter will :.~e of ~_xed -~ength and the inner tLbe w~_11 be o' variable lenc'-=~, such that when the pressure within the 1 u:~:en of tre outer tube is i r~creased, the inner tube will become longitudinally elongated and the flexible deolov~nent s 1 eeve -.H i 11 ever t , thereby causing the delivery cash e'~e= ~.o assu:,:e its second configuration as 2 0 def fined = er eabc ~ a . Ccnver sely, whey. the pr es sure ~~: i thin the lW;:e_''- of t~_e o~:.ter !~ube i s decreased, the inr_er tube w-~ 1 i so= ~er_ and t=~e ~ 1 exible sleeve will invert, t °reby causing ~he aelivery catheter to assume its sscond con =ig~~=aticn as define:. :~ereabove.
I~_ other e~~,aodiments, t_~e outer tube of the de--_ivery catheter is ef variable length and the i:~ner tube is of (fixed length, with t_=' proximal end of the inner tube being a~tached to t::e body of the outer tube, such that when t a I~reSSUre wi chi n the lumen of the outer tube is decreased, tre outer tube will shorten and the flexible deployment sleeve will event, thereby causing the delivery catheter to assume its second configuration as defined hereabove. Conversely, when the pressure within the l~:men of the outer tube is increased, the outer tube will lengthen and the flexible deployment sleeve will invert, thereby causing the delivery catheter to assume its second configuration as defined hereabove.=

Radio dense or radio opaque markers may be formed on the inner and/or outer tubes at locations which :nark the opposite ends of the intraluminal apparatus (e. g., stmt, stented graft, etc.) as it is mounted on the distal portion of the inner tube of the delivery catheter, thereby facilitating precise positioning of the intraluminal apparatus (e. g., stent, stented graft, etc.) prior to radial expansion and implantation thereof.
In some applications, the delivery catheter of the present invention may be used in combination with a self expanding, implantable intraluminal apparatus (i.e., ste..t, scented gnat', etc.) positioned on the distal port_on of the inner tube. In other appiicat~ons, the delivery catheter may be used in combination wit: a nressure-expandable, =~~:piantabie intraluminal apparatus (e.g., stent, scented graft, etc.) which is posit~.oned on an inflatable balloon or other pressure-exerting expansion member mounted or formed on the outer surface of the distal portion of the inner tube.
The delivery catr~eter of the present invention may be o-ovided wit~~ a proximal connector assembly attached to t'_'_~.e proximal end of the inner and outer tubes. Such proximal connector assembly may comprise a tubules= outer bod-.% which defines proximal ar_d distal ends, Y:ith the proximal end of t~:e outer tube being attached to the distal er_d of the outer body. Rotatably connected to the proxi.~:ai end of the outer body is a knob memi~er . In addition to the outer body, the proximal connector assembly may include a tubular inner body which defines oroximai- and distal ends, with the inner body extending through the knob member and into the interior of the outer body. The proximal end of the inner tube is itself attached to the distal end of the inner body. Disposed between the inner and outer bodies of the proximal connector assembly is an elastically deformable sealing member. The kr_ob me:rper is cooperatively engaged to the sealing member such that the rotation of the knob member

6 PCT/US98/12822 in a first direction causes compressive pressure to be applied to the inner body by the sealing member which Drev eats the movement of the inner and outer tubes relative to each otr~e~. Conversely, the rotation of the knob -ember in a second direction opposite the first direction discontinues the application of compressive pressure to the inner body by the sealing member which permits the movement of the inner and outer tubes relative to each other. The outer body of the proximal connector assembly further includes a tubular side arm portion which fluidly co~-~municates with the lumen of the outer tube.
~n accoraance mtn a mrs~ E.'=:ILJVC11111C11L VL 1.11C
nvention, the pate= tube may incorporate a ~.5 ?ong~.t::dirally exter_dable/retractable region (e.g., a telescoping segment, a collapsible/extendable segment/
etc.) such that, when the lumen of the outer tsbe is unpressurized, the flexible sleeve will be inverted into the ~ .:men of the outer tube and the inr_er tube will assume a longitudinally shortened configuration.
Thereafter, when tre lumen of the outer tube is pressurized, the flexible sleeve will assume an everted positicn and the inner tube will become elongated such t~~_at a distal portio:~ of t'~e inner tube upon wi:ic~ the _:~tra-~~::aral ~rosthes=s (e.g., stem, scented graft, etc.) ~s mounted will extend oat of and beyond the distal end of the outer tube. Thereafter, after the intra_u_~.Zinal prosthesis (stmt, stented graft, etc.) has been -mplanted, the pressure within the lumen of~the outer tine may be decreased so as to once again cause the flexible sleeve to become inverted within the lumen of the outer tube with the inner tube assuming its longitudinally shortened configuration.
In accordance with a second embodiment of the invention, the outer tube may incorporate a longitudinally extendable/retractable region (e.g., a telescoping segment, collapsible segment, etc.)w and the WO 98157692 ,~ PCT/US98/12822 inner tube may be of fixed length such that when the lumen of the cuter tube is pressurized, the outer tube will assume a longitudinally lengthened state such that the flexible sieeve and the er_tirety of the inner tube are contained within the lumen of the outer tube.
Thereafter, when the pressure within the outer tube is decreased, the longitudinally extendable/retractable segment of the outer tube will assume a longitudinally shortened co:~figuration thereby causing the distal end of the outer tube to retract such that the flexible sleeve and a distal porti on of the inner tube upon which the intralumina~ prosthesis (e. g., stmt, stented graft, a tc . ; i s me~~-:'.ed wi 11 bece_.,e exposed or uncovered .
F~~.rt:~er i:_ accorcance with the present irwentio_~., there is provided a methcd of delivering a radially expar_dable i=:.raiuminal prosthesis (e. g., stent, stented graft, etc.) to a desired intraluminal site. The method comprises ~ .e i:~itial step of a) providing a delivery catheter wick comprises the above-described inner tube, outer tube, and flexible deployment sleeve, with the delivery catheter further including the radially expandable intraiumiral prosthesis positioned on the distal port-on of the inner tube. Thereafter, b) the ir_ner tube _s advanced over a guide wire until such time as t:~e cistal end of t~~e cuter tube is positio~ed adjacent to t'_~_e treatment site. Thereafter, c} the pressu=a within the lumen at the outer tube is changed so as to cause either i) the distal portion of the inner tube having the scent positioned thereon to be advanced out of aid beyond the distal end of the outer tube or ii) the distal end of the outer tube to retract so as to expose the distal portion of the inner tube on which the intraluminal prosthesis (e. g., stent, stented graft, etc.} is mounted. After the prosthesis has been implanted, the distal portion of the inner tube may be re-positioned within the lumen of the outer tube and the entire delivery catheter is withdrawn. In the event the WO 98/57692 g PCT/US98/12822 delivery catheter is adapted for use with a pressure-expandable intraiuminal prosthesis (i.e., stmt, scented, graft, etc.) rather than a self-expanding intraiuminal prosthesis (i.e., scent, scented graft, etc.), the catheter will typically include an inflatable balloon located on the outer surface of the distal portion ef the inner tube, such ballocn being inflatable subsea_uent to and separately from the pressurization of the lu:,ten of the outer tube, to facilitate the radial expansion of a pressure expandable intraluminal prosthesis (i.e., stem , stented craft, etc.) positioned thereupon.
_Brief D~scri~tion of the Drawings These, as well as other features of the _resent inver_tio-~, will become more apparent upon reference to the drawings Vaherei n Figure 1 ,-s a perspective view of the delivery catheter for a radially expandable intraluminal ster_t constructed in accordance with the p=esent invention;
Figure 2 is a partial longitudinal-sectional view of the delivery catheter of the present invention;
Figure 3 is a longitudiral-sectional view of the dista~ portion of the delivery catheter of the present invention, disposed in an initial configuration whereir_ a radially expandable scent is contained within the delivery catheter;
Figure 4 is a longitudinal-sectional view of the. distal portion of the delivery catheter of the present invention, illustrating the manner in which a self-expanding stmt is deployed from the distal end thereof;
Figure as is a longitudinal-sectional view of the distal portion of the delivery catheter of the present invention, illustrating the manner in which a pressure-expandable stenL is deployed from the distal end thereof;
Figure 5 is a longitudinal-sectional view of a proximal connector assembly which may be mounted on the proximal end of the delivery catheter o~ the present invention;
Figure 6 is a partial longitudinal-sectional view of an embodiment of the delivery catheter havir_g a longitudinally elongateable/retractable inner tube;
Figure 6a is a partial longitudinal-sectional view of an alternative mode of constructioof the inner tube of the embodiment shown in Figure 6;
Figure 7 is a top plan view of a particular self-expanding stmt of the present invention, which r~~ay be utilized in conjunction with the delivery catheter of the present invention; and Figure 7a is a perspective view of the self expanding scent shown in Figure 7 in its operative, rolled configuration for positioning upon the delivery catreter of tie present invention.
Figure 8a is a longitudinal-sectional view of a distal portion. of an alternative embodiment of the delivery catheter having a longitudinally elongateabie/retractable outer tube, disposed in an initial configuration wherein the =adially . expandable stent is contained within the lumen of the outer tube;
Figure 8b is a longitudinal-sectional view of the delivery catheter of Figure 8a, disposed in a deployment configuration wherein the stent is exposed and located outside of the outer tube.
Detailed Description of the Preferred Embodiments Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the invention only, and not for purposes of limiting the scope of the invention in any way, Figure 1 illustrates a delivery catheter 10 which is usable for positioning a radially expandable intraluminai prosthesis (e. g., stent, stented graft, etc.) at a desired treatment site (e. g., a stenosis) within a blood vessel or other anatomical passageway. As will be discussed in more detail below, the preferred construction of the delivery catheter 10 allows for a relatively small diameter, thus facilitating advancement of the delivery catheter 10 through tortuous and/cr small diameter anatomical passageways. Radially expandable vascular scents or scented gra'ts of various designs may be used in conjunction with the delivery cat_~eter 10 of the present inventior_, including self-expa:.ding scents, balloon expandable scents, or ster_ts '~5 whic~ are expandable by o~~her means, such 0.s sten=~s fabricated from shape-memory materials which u::dergo radial expansion when warmed to body temperature.
In the preferred embodiment of the present invention, the delivery catheter 10 is used in COIl~ui1Ct10:1 with a self-expanding stent 12 (as shown in Figures 7 and 7a), the precise structure of which will be discussed in more detail below.
Referring now to Figures 1-3, the delivery caterer 10 comprises an elcngate, flexible cuter tube 14 which defines a proxi~.al e::d 16 and a distal end 18. Exte=ding longitudinally t:rouGh the outer tube 14 is a lumen 20 whic:~ is defined by an inner luminal surface of the outer tube 14. Rigidly attached to the outer surface of the outer tube 14 is an annular radiopaque marker 22,' the distal edge of which is substantially flush with the distal end 18 of the outer tube 14.
In addition to the outer tube 14, the delivery catheter 10 comprises an elongate, flexible inner tube 24 which itself defines a proximal end 26 and a distal end 28. F,xtending longitudinally t:~.rough~ the inner tube 24 is guide wire lumen 30 which is defined by the inner luminal surface of the inner tube 24 and is adapted to accommodate an elongate guide wire 32. As will be discussed in more detail below, the delivery catheter 20 is preferably constructed in one of two general embodiments, tre first of which is shown in Figures 5-6a (having an inner tube 24a, 24b of longitudinally elongateable/re~ractable construction and the second of which is shown in Figures 8a-8b (having an outer tube 14a of longitudinally elor_ga'teable/retractable construction).
The showings of Figures 1-5 are applicable to both of the embodiments shown in Figures 6-5a and 8a-8b, respectively. Also, Figures 7-7a show a specific roil-up stent device 12 which is configured and construc~ed in accordance wits th° p~'esen' invention. This rc=i-up stmt device 12 is one of many radially expandable intraluminal -prostheses (e. g., scents, stented daft, etc.) which are usable in conjunction with the delivery catheter 10 of the present invention.
As seen in Figures 2-4, attached to the cuter surface of the inner tube 24 is an annular, distal radiopaque marker 34, the distal edge of which is substantially flush with the distal end 28 of the inner tube 24. In addition to the distal radiopaque :~arker 34, also attached '~.o tre outer surface of the inner tube 24 at a locaticT proximal to the distal end 28 -s an annular, proxi~;:al radiopaque marker 36. In the delivery catheter 10, a distal portion 38 of the inner tube 24 is defined between the distal and proximal radiopaque markers 34, 35. As will also be described in more detail below, the distal portion 38 of the inner tube 24 is adapted -to have a vascular stmt (e.g. , the stet 12) positioned thereupon for deployment into a desired treatment site.
The delivery catheter 10 constructed in accordance with the preferred embodiment of the present invention further comprises a flexible deployment sleeve 40 having a first end 42 which is attached to the outer tube 14 and a second end 44 which: attached to the inner 'tube 24.

More particularly, the first end 42 of the sleeve 40 is rigidly captured between the radiopaque marker 22 and the outer surface of the outer tube 14, with the second end 44 of the sleeve 40 being rigidly captured between the proximal radiopaque marker 36 and the outer surface of the inner tube 24. Alternatively, outer tube 14 and sleeve 40 may be made from one piece, e.g., by thinning and/or expanding the distal segment of outer tube 14 to form sleeve 40.
Referring now to Figure 5, attached to the proximal ends 15, 25 0~ the outer and inner tubes 14, 24 is a proxima-_ connec~~or assembly 46. In the preferred e~nbodime;~t, the proximal connector assembly 46 co~~pri ses a tabular ov~~er body 48 having a proximal end 50, a distal end 52 and an inner surface which defines an interior char.~er 54. The proximal portion of the inner surface of 'e outer body 48 is internally threaded to facilitate t=a threadable engagement of a knob member 56 to the proximal e:~d 50 of the outer bcdy 48. _n the delivery catheter 10, the proximal end 16 of the outer tube 14 is rigidly attached to the distal end 52 of the outer b.cdy 48 . ~=ore par titularly, a proximal por Lion of the outer surface o~ the outer tube 14 is rigidly secured to a d-stal portion of the inner surface of the ov~ter body 48. The attac.~~:ent of the outer tube 14 to the outer body a8 is preFerably facilitated through the use of an adhesive, though other bonding techniques may also be emp-Toyed in the delivery catheter 10. When the outer tube i4 is attached to the outer body 48, the lumen 20 fluidly-comrnunicates with the interior chamber 54. The outer body 48 further includes an integral tubular side arm portion 58 which also fluidly communicates with the interior cha~-nber 54, and hence the lumen 20 of the outer tube 14.
The proXimal connector assembly 46 of the delivery catheter 10 further comprises a tubular inner body 60 which defines a proximal end and a distal end~62. The inner body 60 is extended through a passage extending axially throug:~ the knob member 56, such that the distal end 62 thereof resides within the interior cha.-nber 54 of the outer body 48. the proximal end 26 of the inner tube 24 is rigidly attached to the distal end 62 of the inner body 60. More particularly, a proximal portion o. the outer surface of the inner tube 24 is rigidly secured to a distal portion of the inner surface of the inner body 60. The attacrment cf the inner tube 24 to the inner body 60 is also preferably facilitated through the use of an adhesive, though alternative bonding techniques may also be employed ir. the delivery catheter 10.
In addition to the aforementioned structural components, the b~cximai connector assembly 46 f::~ther includes an elastically deformable sealing member 64 whic:~ is disposed and captured between the inner surface of the outer body 48 and the outer surface of the inner body 60. The sealing member 64 preferably comprises a 0-ring which is compressible, and fabricated f=om a iubricous material. 4rhen captured between the outer and inner bodies 48, 60, the sealing member 64 creates a fluid-tight seal therebetween, thus preventing the escape of any fluid within. the interior chamber 54 from the aroximai end 50 of t::~e outer body 48 (i.e., from between the outer body 48 and knob member 56).
In the proximal connector assembly 46, the cistal end of the knob member 56 is cooperatively e__~_gaged to the sealing member 64 such that the tightening of the knob member 55 (i.e., the rotation of the knob member 56~in a clockwise direction) facilitates the compression o~ the sealing member 64. The compression of the sealing :.~.ember 64 causes compressive pressure to be applied to the inner body 60 thereby, thus preventing any movement of the outer and inner tubes 14, 24 relative to each other. In 'his respect,~since the outer tube 14 is attached to the outer body 48 and the inner tube 24 to the inner bcdy 60, maintaining the inner body 60 in fixed relation to the outer body 48 by the compression of the sealing member 64 likewise maintains the outer and inner tubes i4, 24 in fixed relation to each other. Conversely, the loosening of t .e knob member 5 5 ( i . a . , the ro ration of the knob member 56 in a counter-cloc'~cwise direction) discontinues the application of compressive pressure to the inner body 60 by the sealing me~-nber 64, thus permitting the movement of ':~e outer and inner tubes 14, 24 relative to each other. Because compressive pressure is applied thereto, the -nner body 60 is preferably of rigid construction so as to resist crushing or collapse when the sealing member 64 is compressed thereagainst. In this respect, the in ne= body 60 is preferably fabricated from a etal mate-iai, though other suitable rigid materials.,a:ay also be ~.:sed as an ai terr_ativ a to me tal .
Referring now to Figures 3 and 4, the delivery catheter 10 may be used to deliver and implant a self-expandir_g stmt, such as the particular roil-up stmt 12 shown i:~ Figures 7 and 7a. The delivery catheter 10 is used to deploy the stent 12 into a treatment sire by init-a--_ly positioning the rolled stmt 12 upon the distal port=on 38 of the lnne_ tube 24. Subsequent to mo~.:nting of ..tee scent 12 on the distal portion 38 of tre _nr.er tuwe, t~e distal port=on 3b or tie inner tLbe 24 (~_avir_g tine stmt i.2 mounted hereon) ~s whclly positioned -..ithin the _~amen 20 of the outer tube 14 . The posi tior_=r_g of the distal portion 38 within the lumen 20 is facilitated by lcosening the knob member 56 of the proximal connector asse:,,bly 46. When the distal portion 38 (havin g' the stmt 12 positioned thereupon) is fully positioned within the lumen 20, the sleeve 40 is proximally stretched between the outer and inner tubes 14, 24, with the distal radiopaque marker of the inner tube 24 being concentrically positioned relative to the radiopaque marker 22 of the outer tube 14. Additionally, an annular, conically shaped space is defined between the sleeve 40 and the inner luminai surface of the outer tube 14.
After the distal portion 38 has been positioned within the lumen 20, the knob member 56 of the proximal connector assembly 46 is re-tightened, thus preventing any movement of either of the outer or inner tubes 14, 24 relative to the other.
The inner tube 24 of the delivery catheter i0 is then advanced over the intraluminaliy positioned guide wire 32 whic'.~.~. is extended into the guide wire lumen 30 of the ir:ner tube 24. This allows the delivery catheter 10 to be advanced over the pre-inserted guide wire 32 until such t~.me as t'~e distal end 18 oL the outer tube 14 is disposed at a desired location relative to the side at which tie s~_ent 12 is to be implanted. The distal end 18 of the ou~e= tube 14 is precisely positionable relative to the ~mpiantation site, due to the presence of the radiopacr,~e ~::arker 22 thereon. As will be recognized, due to the knob :~e~r~ber 56 of the proximal connector assembly 46 being tightened, the outer and inner tubes 14, 24 may be advanced as a unit ever the guide wire 32.
As best seen in Figure 4, subsequent to the placement o. the distal end 18 of the outer tube 14 at the desired location relative to the implantation site, the knob ~:~e::~.ber 56 ef the proximal connector assembly 46 is once agai_~_ loosened so as to allow for axial movement of one o~ t~~e oater or inner tubes i4, 24 relative to the other. The lumen 20 of the outer tube 14 is then pressurized with a fluid (e.g., sterile saline or contrast media) via the side arm portion 58 of the outer body 48 0~ the proximal connector assembly 46. The fluid flows into the space defined between the sleeve 40 and the inner iuminal surface of the outer tube 14, with fluid pressure being exerted distally against the sleeve 40.
The a~~lication of such distally directed fluid pressure against the sleeve 40 results is a-ither i) distally directed longitudinal advancement of the distal portion 38 of the inner tube 14 from the distal end 18 of the outer tube 14 with concomitant eversion of the flexible sleeve 40 (see Figures 6 and 7) or ii) proximally directed longitudinal retraction of the distal portion of the outer tube 14 with concomitant evers_on of the flexible sleeve 40 so as to uncover and expose the distal portion 38 of the inner tube 14. In tris respect, with t=~-a knob member 55 being loosened, the outer body 48 of the proximal connector assembly 46 is tightly grasped as t'~e lumen 20 is pressurized with the fluid, thus allowing for elongation of the inner tube 24 relative to the ou t°= tube 14 , or shcrtening of the cuter tube 14 relative to the inner tube 24. As will be recog__~_ized, once the radiopaque markers 22, 36 are concentrically oriented relative to each other, the scent 12 positioned upon the distal portion 38 is completely uncovered and is no longer surrounded by the lumen 20 of the outer tube 14.
In applications where the sent 12 is of the self-expanding variety, t':e s tent 12 will undergo i~:~;~ediate radial expansion into engagement with the lu~-ninai surface of the anatomical passageway upon being removed from withithe lumen 20 cf the outer tube 14 is the 2 5 of ore:,:e~ cloned man~er . Ref erence to the radiopaque marks=s 22, 34, 35 alicws for confirmation of the proper orientatio:~ of the scent 12 relative to the treatment site. Subseguert to the deployment of the stent 12, the distal portion 38 of the inner tube 24 is proximally drawn- back into the lumen 20 of the outer tube i4 by pulling the inner body 60 of the proximal connector assembly 46 in the a~orementioned manner. Thereafter, the knob member 56 of the proximal connector assembly 46 is re-tightened, with the delivery catheter 10 then being wit:~dra-~rn from over the guide wire 32.
In other applications, as specifically shown in Figure 4a, the delivery catheter 10 of the' present WO 98/57692 1,~ PCT/US98/12822 invention may be used in conjunction with a pressure-expandable stmt 66 rather than with the self-expanding stent 12. When the delivery catheter 10 is used in conjunction with the pressure expandable scent 66, the inner tube 24 thereof is typically modified to include an inflatable balloon 68 of other pressure exerting element mounted on the distal portion 38 of the inner tube 24, between the distal and proximal radiopaque markers 34, 36. In this respect, the pressure expandable scent 56 is posit=oned over the deflated balloon 68, and is then positior_ed within the lumen 20 of the outer tube .4, as seen in Figure 2. As seer. in Figure 4a, subsequent to the oosit-:~oning o= the radiopaque marker 22 at the desired locaticz rpiative to the intended imalantation site, the stent 66 is exposed by either i) a distal advancement and elongation of the inner tube (see Figures 6 and 6a) or ii) proximal retraction and shortening of the outer tube 14 (see Figures 8 and 8a), such t'~at the sleeve 40 is distally everted and drawn taunt, with the nroximai radiopaque marker 36 of the inner tube 24 loca~ed a spaced distance beyond the radiopaque ~~~arker 22 of t~e outer tube 14.
~f~hen the distal portion 38 bearing the scent 66 is deployed in the previously described manner, reference is r.;ade to the distal a:~d proximal radiopaque markers 34, 35 to insure the proper orientation of the scent 66 relative to tile Lreatment site. Thereafter, the balloon 68 is inflated, thus facilitating the radial expansion of the ster_t 66 into contact with the luminal surface of~~ the anatomical passage. The balloon 68 is then deflated, with the distal portion 38 then being proximally drawn back into the lumen 20 by the proximal movement of the inner tube 24 relative to the outer tube 14 accomplished by pulling the inner body 60 of the proximal connector ' 35 assembly 46 (with the knob member 56 being loosened) while tightly grasping the outer body 48 thereof.
~'ir.-~~,nryiman+-~ r,T the nP~;vPrv catheter=

WO 98/57692 1 g PCT/US98/12822 uavira Eionaateable/Retractable Inner Tube Referring now to Figure 6, the delivery catheter 10 of t-,e present invention may alternatively be configured to incorporate an inner tube 24a having a proximal end 26a which is attached to the outer tube 14 such t~at the guide wire lumen 30a of the inner tube 24a communicates wits. the outer surface of the outer tube 14. As will be recognized, if the inner tuber 24a is incorporated into the delivery catheter 10, the proximal connector assembly 46 will have a modified configuration, with only the proximal er_d of the outer tube 14 being attached thereto.
Though r.ot shown, the distal region of t:ie inner tube 24a is identically configured to that oT the pre-~io~~s--y described inner tube 24, and includes. a distal portion. defined between distal and proximal radiopaaue mar~ers, with the distal portion being adapted to have a sel--expanding scent positioned thereupon, or being provided with an inflatable balloon for use with a pressure expar_dable stent. Additionally, the opposed enas of a flexible sleeve are attached to and extend betwee~ the cuter tube i4 and the inner tube 24a in the same manner as previously described in relation to the sleeve ~0 and outer aid inner tubes i4, 24.
v~~_en t~'~e delivery catheter 10 incorporates the ir_rer tube 24a, the deployment of either a self-expanding scent or a pressure expandable stent from within the lumen 20 of the outer tube 14 is facilitated by the distal advancement of the distal portion of the inner tube 24a from the distal end 18 of the outer tube 14. Since the proximal. end 26a of the inner tube 24a is rigidly secured to the outer tube 14, such distal advancement is accomplished by providing the inner tube 24a with an expandable region 70 preferably having a bellows-like config~~ration. In this respect, when the lu~-nen 20 of the outer tube 14 is pressurized with the fluid, distally directed fluid pressure is exerted against the sleeve, tr~~a causing the longit,~adinal stretching of the=expanded region 70. Such stretching of the expanded region 70 allows the inner tube 24a to move distally relative to the cuter tube 14, and thus facilitates the distal advancement of the distal portion of the inner tube 24a from the distal end i8 of the outer tube 14. The expandable region 70 is preferably sized such that when fully stretched, the distal portion of the inner tube 24a bearing the stent is completely removed from within the lumen 20 of the outer tube 14.
Referring now to Figure 6a, as an alternative to the inner tube 24a, the delivery catheter 10 may be provided with an inner rube 24b. The inner tube 24b comprises a ~ubular outer sleeve 72 having a proximal end 74 and a distal end 76. The proximal er.d 74 of the outer sleeve 72 is rigidly secured to the outer tube 14 such that the lumen 78 of tre outer sleeve 22 com~-nunicates with the outer surface of the outer body 14. Ir~ addition to the outer sleeve 72, the inner tube 24b includes a tubular inner sl eeve 80 having a proximal end 82 and a distal end. Thoug~; not shown, the distal region of the inner sleeve 80 is identically configured to the distal region of tre i ~~ er tube 24.
In the inner tube 24b, the proximal end 82 of the inner sleeve 80 is d_sposed within the lumen 78 ef the outer s-eeve 72 and slidabiy movable therewitrin. The inr_er sleeve 80 itself defines a lumen 84 which communicates vaith the lumen 78 of the outer sleeve 72 when the outer and inner sleeves 72, 80 are slidably attached to each other in the aforementioned manner.
Importantly, when the lumen 20 of the outer tube 14 is pressurized with the fluid, the distally directed pressure exerted against the sleeve results in the sliding movement of the inner sleeve 80 distally relative to the o~~,ter sl eeve 72 . Such distal movement of the inner sleeve 80 facilitates the distal advancement of the distal portion thereof from the distal end 18 of the outer tube i4. The overlap between the outer -and inner WO 98/57692 2o PCT/US98/12822 sleeves 72, 80 is sized such that the inner sleeve 80 may be distally moved relative to the outer sleeve 72 in an amount sufficient,to facilitate the complete removal of the distal portion of the inner sleeve 80 bearing the scent from within the lamer- 20 of the outer tube 14.
Embodiments of thA Deiiverv Catheter Hav~ra Eloraateable/Retractable Outer Tube An alternative embodiment of the preferred deli very catheter 10 is shown in Figures 8a and 8b. This i0 alternative e~rc~odiment comprises an elongate pliable outer tube 14a whic~~ has a collapsible segment 90. The collapsible seament 90 of the outer tube 14a may be formed of a plastic film or membrane bonded to separate segme~ts of t= a o;:ter tube 14a, or as shown is the 13 drawin gs may ccmpri se a portion of the outer tube 1 4a whic'_: '_'_~_as beer_ draw: or otherwise reduced to a wall thickness whicis narrower than that of the remainder of the outer tine 14a so as to permit folding or pliability of that collapsible segment 90. Scored regions, living 20 hinges or relatively pliable areas may be formed at discrete locations in the collapsible segment 90 to cause the collapsible segment 90 to longitudinally collapse or fold ~:~ a zig-zag (e.g., "accordion") manner, as shown in Figure 8b.
25 ~~~:e i~.rer tu:ce 24 of t his alternative embodiment is a continuous, ~on-telescoping, non-collapsible tubular member having a proximal end anchored to the outer tube 14a at the side opening 25 and a distal end whereupon the scent ~2 is mounted.
30 Depending on the relative structural integrity and rigidity of the collapsible segment 90 of the outer tube 14a, it may be desirable to provide an optional stiffer_ing member 92, such as a wire, within the lumen 20a oy the outer tube. Such stiffening member 92 will be 35 disposed within the lumen 20a of the outer tube 14a wren this alternative embodiment of the catheter 10 is in its initial configuration shown in Figure 8a, wherein the stent 12 is positioned within the lumen 20a of the outer tube 14a. The stiffening member 92 will prevent the outer tube 14a from bending or sagging in the region of the collapsible segment 90 when the outer tube 14a is in its elongated configuration shown in Figure 8a.
Thereafter, when negative pressure is applied to the lumen 20a of the outer tube 14a so as to draw the outer tube 14a to its longitudinally contracted state shown in Figure 8b, the stiffening wire may optionally be removed i0 or retracted as the collapsible segment 90, when in such collapsed configuration shown in Figure 8b, will be less likely to undergo inadse_te:~t bending or sagging.
Thus, when the embodi:~e::t s hown in Figures 8a and 8b s used, the scent 12 will be initially mcunted on the distal portion of the inner tube 24 and, thereafter, positive pressure will be applied to the lu.~nen 20a of the outer tube 14a so as to cause the collapsible segment 90 of the outer tube i4a to assume its extended configuration. Due to the fact that the inner tube 24 is of fixed length with its proximal end being soundly anchored and attached to the body of the outer tube 14a, such applicaticn of positive or increased pressure to the lumen 20a of the outer tube i4a will cause the distal portion of the outer tube 14a to advanced over anal fully Surround the distal portion of the inner tube 24 whereupon the stent 12 is mounted. Concurrently, the flexible sleeve 40 will assume an inverted position within the lumen 20a of the outer tube I4a, as shown in F~aure 8a.
With this embodiment of the catheter device 10 disposed in the configuration shown in Figure 8a, the proximal end of a propositioned guide wire 32 may be inserted into the distal end of the inner tube lumen 26, and the catheter may then be advanced over such propositioned guide wire 32 until the stent 12 becomes located at its desired implantation site, as evidenced by radiologic visualization of the markers 34 and 36 located at either end of the scent 12.
Thereafter, the pressure within the lumen 20a of the outer tube 14a is decreased (e.g., by application of suction to the lumen 20a), so as to draw the outer tube 14a to a longitudinally contracted or shortened length wherein. the collapsible segment 90 is fully collapsed (e. g., folded, compressed) as shown in Figure 8b. Such shortening of the outer tube 14a causes the distal end of the outer tube 14a to retract in the proximal direction, thereby exposinc the stmt 12 and causing the sleeve 40 to become everted, as shown i-~. Figure 8b. In embodiments wherein the stmt 12 is of the pressure expandable variety, a balloon inflation fluid or other force will then 'ae used to exert outward radial pressure against the stem 12 to radially expand and plastically deform the scent such that it will remain into contact with the surrounding luminal surface. In other embodiments wherein the stent 12 is of the self-expanding variety, the .a.ere removal of the outer tube 14a from the area surrounding the stmt 12 will allow the scent 12 to self-expand to its desired radially expanded configuration in which it will contact and engage the luminal surface of the svrrourding blood vessel wall.
A Roli-U~ Ster_t Device of the Present Invention Referring now to Figures 7 and 7a, as previously explained, the delivery catheter 10 of the present invention is preferably used in conjunction with the self-expanding stmt 12. The stmt 12 is of a metallic design,- and is fabricated by milling or chemically etching a rectangularly configured, thin-walled sheet 86 to include a desired pattern of elongate slots 88, each of w~~ich has a longitudinal axis. The preferred pattern of tze slots 88 consists of a series of rows of rectangular slots, with the longitudinal axes of the slots 88 in each row being linearly aligned with each other and extending ~in parallel relation to the longitudinal axes of the slots 88 in the remaining rows.
The sheet 86 has a preferred thickness of from approximately 0.0005 inches to 0.004 inches. Subsequent to the slots 88 being formed therein, the sheet 86 is rolled longitudinally into the tubular shape shown in Figure 7a. The pattern of the slots 88 within the sheet 86 will typically be varied according to the intended application of the scent 12. In this respect, the pattern of the slots 88 shown in Figure 7 is preferred when the stmt 12 is to be used in relation to blood flow applications since, as seen in Figure 7a, the longitudinal axes of the slots 88 will be parallel to the direction oz blood flow ;when the stent 12 is operatively positioned, thus promoting laminar blood flow therethrough. The sheet 86 may be fabricated from a radiopaque material, or may have radiopaque markers embedded therein.
As previously indicated, in addition to the self expanding stmt 12 and the pressure expandable stent 66, the delivery catheter 10 may be used in conjunction with other scent designs. Such alternative stent designs include those stems fabricated from shape memory materials. Additionally, the pressure expandable or self-expanding stems with which the delivery catheter 10 is utilized may be fabricated from wire, flat wire, or various other materials.
The delivery system. constructed in accordance with the present invention provides numerous advantages over stmt delivery syste.~a known in the prior art. In prior art delivery systems, a sheath must be manually moved relative to a delivery catheter to facilitate the deployment of the stent. As such, the materials of the sheath and the delivery catheter must be thick walled and/or stiff. Such designs result in the catheter delivery system being too stiff or bulky to be effectively used in small vessels and/or tortuous anatomical passageways.' The present delivery system uses fluid pressure to deploy the stmt from the delivery catheter. As such, the stent deployment using the present delivery system is conducted in a much more controlled manner, with the present design allowing for the use of very thin-walled and flexible materials for the outer and inner tubes 14, 24. The use of such materials results in a delivery system that is smaller and significantly more flexible than those known in the prior art.
Additional modifications and improvements of the present invention may also be apparent to those skilled in the art. Thus, she part-cular combination of parts described and iilustra'~ed herein is intended to represent only certain e.«bodiments of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A delivery catheter for delivering a radially expandable intraluminal apparatus to a desired location within a body lumen, said catheter comprising:
a) an outer tube having a proximal end, a distal end, and a lumen extending longitudinally therethrough;
b) an inner tube having a proximal end, a distal end, and a lumen extending longitudinally therethrough, the proximal end of said inner tube being attached to the outer tube, said inner tube having a distal portion upon which the intraluminal apparatus may be mounted; and c) a flexible sleeve having a first end attached to a distal portion of the outer tube and a second end attached to the inner tube at a location which is proximal to said distal portion of said inner tube, said sleeve forming a substantially fluid-tight seal between said inner tube and said cuter tube such that the pressure within. the lumen of the outer tube and surrounding said inner tube may be volitionally increased and decreased;
d) at least one of said outer tube and said inner tube being of variable length, such that in response to changes in the pressure within the lumen of the outer tube, the delivery catheter will transition between:
a first configuration wherein the distal portion of the inner tube is surrounded laterally by the outer tube; and a second configuration wherein the distal portion of the inner tube is not surrounded laterally by said outer tube.

2. The delivery catheter of Claim 1 wherein said outer tube is of fixed length and said inner tube is of variable length such that, when the pressure within the lumen of the outer tube is increased while the catheter is in its first configuration, the inner tube will lengthen and the flexible deployment sleeve will exert, thereby causing the catheter to assume its second configuration.

3, The delivery catheter of Claim 2 wherein the variability in length of the inner tube is by way of a collapsible segment of the inner tube such that the inner tube is initially deployable in a longitudinally shortened state wherein said collapsible portion is collapsed, and is subsequently transitionable to a longitudinally extended state wherein said collapsible portion is extended.

4, The delivery catheter of Claim 3 wherein the collapsible segment of the inner tube is a telescoping segment formed of an inner tube portion and an outer tube portion, at least one of said inner and outer tube portions being axially slidable relative to the other, in telescoping fashion.

5. The delivery catheter of Claim 3 wherein the collapsible segment of the inner tube is a pliable segment capable of folding to a longitudinally shortened state.

6. The delivery catheter of Claim 1 wherein. said inner tube is of fixed length and said outer tube is of variable length, such that when the pressure within the lumen of the outer is decreased while the catheter is in its first configuration, the outer tube will shorten and the flexible sleeve will event, thereby causing the catheter to assume its second configuration.

7. The delivery catheter of Claim 5 wherein the variability in length of the outer tube is by way of a collapsible segment formed in the outer tube, said collapsible segment being initially deployable in a longitudinally elongated configuration wherein the outer tube is a first length, and being subsequently transitionable to a longitudinally shortened configuration wherein said outer tube is of a second length, said second length being shorter than said first length.

8. The delivery catheter of Claim 7 wherein the collapsible segment of the outer tube is a telescoping segment formed of an inner tube portion and an outer tube portion, at least one of said inner and outer tube portions being axially slidable relative to the outer, in telescoping fashion.

9. The delivery catheter of Claim 7 wherein the collapsible segment of the outer tube is a pliable segment capable of folding to a longitudinally shortened state.

10. The delivery catheter of Claim 1 wherein said outer tube includes a radiopaque marker attached to the distal end thereof.

11. The delivery catheter of Claim 10 wherein the first end of the sleeve is rigidly captured between said radiopaque marker and said outer tube.

12. The delivery catheter of Claim 1 wherein said inner tube includes a distal radiopaque marker attached to the distal end thereof and a proximal radiopaque marker attached thereto at a location proximal to the distal end thereof, the distal portion of the inner tube being defined between the distal and proximal radiopaque markers.

13. The delivery catheter of Claim 12 wherein the second end of the sleeve is rigidly captured between the proximal radiopaque marker and the inner tube.

14. The delivery catheter of Claim 1 further comprising an inflatable balloon disposed on the distal portion of the inner tube.

15. The delivery catheter of Claim 1 further comprising a proximal connector assembly attached to the proximal ends of the inner and outer tubes, said proximal connector assembly comprising:

a) a tubular outer body defining proximal and distal ends, the proximal end of the outer tube being attached to the distal end of the outer body;
b) a knob member rotatably connected to the proximal end of the outer body;
c) a tubular inner body defining proximal and distal ends, said inner body extending through the knob member and into the outer body, the proximal end of the inner tube being attached to the distal end of the inner body; and d) an elastically deformable sealing member disposes between the inner and outer bodies;
e) said knob member being cooperatively engaged to the sealing member such that the rotation of the knob member in a first direction causes compressive pressure to be applied to the inner body by the sealing member which prevents the movement of the inner and outer tubes relative to each other, and the rotation of the knob member in a second direction opposite the first direction discontinues the application of compressive pressure to the inner body by the sealing member which permits the movement of the inner and outer tubes relative to each other.

16. The delivery catheter of Claim 15 wherein said outer body of the proximal connector assembly includes a tubular side arm portion which fluidly communicates with the lumen of the outer tube.

17. A system for implanting a radially expandable intraluminal apparatus within a body lumen, said system comprising the delivery catheter of Claim 1 in combination with a radially expandable intraluminal apparatus mounted on the distal portion of the inner tube, distal to the site at which the distal end of the sleeve is attached to the inner tube.

18. A method for delivering a radially expandable intraluminal apparatus to a desired site within a body lumen, said method comprising the steps of:
a) an outer tube having a proximal end, a distal end, and a lumen extending longitudinally therethrough;
b) an inner tube having a proximal end, a distal end, and a lumen extending longitudinally therethrough, the proximal end of said inner tube being attached to the outer tube, said inner tube having a distal portion upon which the intraluminal apparatus may be mounted; and c) a flexible sleeve having a first end attached to a distal portion of the outer tube and a second end attached to the inner tube at a location which is proximal to said distal portion of said inner tube, said sleeve forming a substantially fluid-tight seal between said inner tube and said outer tube such that the pressure within the lumen of the outer tube and surrounding said inner tube may be volitionally increased and decreased;
d) at least one of said outer tube and said inner tube being of variable length, such that in response to changes in the pressure within the lumen of the outer tube, the delivery catheter will transition between:
a first configuration wherein the distal portion of the inner tube is surrounded laterally by the outer tube; and a second configuration wherein the distal portion of the inner tube is not surrounded laterally by said outer tube.
and, a radially expandable intraluminal apparatus mounted on the distal portion of the inner tube;

b) with the catheter disposed in its first configuration, inserting the catheter into a mammalian body such that the distal end of the catheter is located at a desired location within a body lumen;
c) changing the pressure within the lumen of the outer tube of the delivery catheter so as to cause the delivery catheter to transition to its second configuration; and d) causing the intraluminal apparatus to radially expand into contact with the body lumen, and to become separated from the delivery catheter.

19. The method of Claim 18 further comprising the step of:
e) subsequently changing the pressure within the lumen of the outer tube to cause the delivery catheter to return its first configuration.

20. The method of Claim 19 further comprising the step of:
f) removing the delivery catheter from the body, while the intraluminal apparatus remains implanted within the body lumen.

21. The method of Claim 18 wherein the delivery catheter provided in step a, has an outer tube of variable length and an inner tube of fixed length, and wherein the change in pressure accomplished in step c of the method is a decrease is pressure.

22. The method of Claim 18 wherein the delivery catheter provided in step a has an outer tube of fixed length and an inner tube of variable length, and wherein the change in pressure accomplished in step c is an increase in pressure.

23. The method of Claim 21 wherein the delivery catheter provided in step a, which has an outer tube of variable length and an inner tube of fixed length, further comprises a stiffening element which is at least temporarily deployable within the outer tube to prevent the outer tube from undergoing unwanted deformation while the delivery catheter is in its first configuration.