Ulllted States Patent [19]
`Gianturco
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,580,568
`Apr. 8, 1986
`
`OTHER PUBLICATIONS
`Charles T. Dotter, “Trans. .
`.
`. Tube Graft”, 329-332,
`Investlganve Radlology 94969;
`_
`Carlos T. Potter, “Trans .
`.
`. St1nt Grating”, Technlcal
`Developments, 4-1983.
`Andrew cragg’ “Nonsurgical .
`261-263, Radiology, 4-1983.
`Morris Simons, “Vena Cava . . . Memory Alloy”, 89-94,
`Radiology’ 1O__1977‘
`
`_ Nitind Wire”,
`
`‘
`
`Primary Examiner-Robert P. Swiatek
`Assistant Examiner-John G. Weiss
`Attorney, Agent, or Firm--Woodard, Weikart, Emhardt
`& Na ht
`“g 0“
`
`ABSTRACT
`[57]
`An endovascular stent formed of stainless steel wire of
`0.018 inches diameter and arranged in a closed zig-zag
`pattern. The stent is compressed into a reduced size
`shape of an outer diameter which is many times smaller
`than its expanded shape. The stent is positioned in a
`passageway in the vascular system by means of a sheath
`while the stent is retained in the compressed reduced
`Size shape_ A ?at_ended catheter is used through the
`sheath to hold the stent in place in the passageway
`while the sheath is withdrawn from the passageway
`allowing the stent to expand in the passageway into its
`expanded Shape t° hold the passageway 0P6“ and en'
`larged. Other possible applications of the stent are in the
`respiratory, biliary and urinary tracts to reinforce col
`lapsing structures.
`
`10 Claims, 10 Drawing Figures
`
`[54] PERCUTANEOUS ENDOVASCULAR STENT
`AND METHOD FOR INSERTION THEREOF
`
`[75] Inventor:
`
`Cesare Gianturco, Champaign, Ill.
`
`.
`_
`.
`[73] Assignee. lCntgrk, Incorporated, Bloommgton,
`'
`_
`
`[21] Appl. NO.: 656,261
`
`Oct’ 1’ 1984
`
`_
`-
`[22] F?ed'
`A61M 29/00
`[51] I t C14
`n .
`.
`........................................... ..
`128/345; 138/97;
`[52] us. c1. ................................
`604/96; 267/182
`[58] Field of Search ------------- -- 128/345’ 341’ 343’ 1 R’
`128/334 R; 138/97, 119; 604/93, 96, 102,
`104-107; 267/180’ 182
`
`[56]
`
`References Cited
`U S PATENT DOCUMENTS
`'
`'
`
`....... "- ........................ .
`
`128/325
`
`3,540,431 11/1970 Mobm‘uddm '
`"
`800k] ""
`""" "
`""" " 128 /3 45
`3’868’956 3/1975 Aggie; Z] a '
`'
`1:12.. 604/96
`4,141,364 2/1979 Schultze
`__ 604/104
`4:407:271 10/1933 Schiff ____ __
`4,425,908 1/1984 Simon ............................... .. 128/1 R
`FOREIGN PATENT DOCUMENTS
`894257 12/1981 U.S.S.R. ............................ .. 267/182
`
`-////
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-1
`
`

`
`US. Patent Apr. 8, 1986
`
`Sheet 1 of 3
`
`4,580,568
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-2
`
`

`
`U.S. Patent Apr. 8, 1986
`
`Sheet20f3
`
`4,580,568
`
`A
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-3
`
`

`
`US. Patent Apr. 8, 1986
`
`Sheet 3 of3
`
`4,580,568
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-4
`
`

`
`1
`
`PERCUTANEOUS ENDOVASCULAR STENT AND
`METHOD FOR INSERTION THEREOF
`
`20
`
`35
`
`BACKGROUND OF THE INVENTION
`'1. Field of the Invention
`This invention relates to stents and a method for
`inserting a stent.
`2. Brief Description of the Prior Art
`It is desirable in various situations that means be pro
`vided for expanding a constricted vessel portion or for
`maintaining an open passageway through a vessel por
`tion. Such situations arise, for example, in conjunction
`with the disease known as arteriosclerosis as well as the
`growth of a tumor so as to restrict or stop ?ow of blood
`through a blood vessel. Dr. Charles Dotter et al. re
`ported in 1969 on the experimental use of coiled stain
`less steel wire stents placed in the popliteal arteries of
`dogs. Although the coils‘ exhibited long-term patency,
`narrowing of the lumen occurred within them and only
`small coils could be passed percutaneously. See Dotter
`CT et al., T ransluminally-Placed Coilspring Endoarterial
`Tube Grafts, Invest. Radiol., 1969; 42329-3321. Re
`cently, two laboratories reported on the use of a pros
`25
`thesis constructed of a thermal shape memory alloy,‘
`nitinol, which is passed through a catheter. See Dotter
`CT et al., T ransluminal Expandable Nitinol Coil Stent
`Grafting, Radiology, April, 1983; 147259-2602, and
`Cragg A. et al., Nonsurgical Placement of Arterial Endo
`prostheses, Radiology, April, 1983; l47:26l-2633. Such
`stents can be complicated to use, requiring ice water or
`heated saline for placement. Also they have been found
`to produce luminal narrowing due to ?brin deposition
`on the stent wires.
`Other references which may have relevance to the
`present invention are the following U.S. patents: Sakura
`US. Pat. No. 4,214,587; Al?di U.S. Pat. No. 3,868,956;
`and Simon US. Pat. No. 4,425,908; and the Russian Pat.
`No. 978,821; also the following publications: C. Gian
`turco et al., A new vena cava ?lter: experimental animal
`40
`evaluation, Radiology, December, 1980; 137:835-837“;
`and M. Simon et al., A Vena Cava Filter Using Thermal
`Shape Memory Alloy, Diagnostic Radiology, 125:89-94,
`October 19775. Still another reference publication is D.
`Maass et al., Radiology Follow-up of Transluminally In
`serted Vascular Endoprostheses: An Experimental Study
`Using Expanding Sprials, Radiology, September 1984;
`152:659-663.
`Objects of the invention are to provide a stent which
`is easy to place and use that reduces ?ow defects, lumi
`nal narrowing and occlusion.
`SUMMARY OF THE INVENTION
`One embodiment of the stent of the present invention
`might include a wire formed into a closed zig-zag con
`?guration including an endless series of straight sections
`joined by bends. The stent is resiliently compressible
`into a smaller ?rst shape wherein the straight sections
`are arranged side-by-side and closely adjacent one an
`other for insertion into a passageway. The stent is resil
`iently expandable into a larger second shape wherein
`said straight sections press against the walls of the pas
`sageway to maintain it open.
`One embodiment of the method of the present inven
`tion might involve inserting a stent by compressing a
`stent including a wire formed in a closed zig-zag con?g
`uration into a ?rst shape wherein the zigzag con?gura
`tion includes side-by-side closely adjacent straight sec
`
`4,580,568
`2
`tions joined by bends with a stress therein. The com
`pressed wire stent is then moved into a sheath. The
`sheath is then located with the distal end thereof in a
`passageway with the compressed wire within the distal
`end of the sheath. The sheath is then removed from the
`passageway while holding the stent in place, whereby
`the stress in the stent causes it to expand in the passage
`way to hold the passageway open and enlarged.
`BRIEF DESCRIPTION OF THE ‘DRAWINGS
`FIG. 1 is a side elevation of a preferred embodiment
`of the present invention.
`FIG. 2 is an end elevation of the structure of FIG. 1.
`FIG. 3 is a section through a blood vessel showing a
`tumor reducing the size of the blood vessel.
`FIG. 4 is a view similar to FIG. 3 showing one of the
`steps of the method of inserting the stent of the present
`invention.
`FIGS. 5 and 6 are serial views showing further steps
`in the method illustrated in FIG. 4.
`FIG. 7 is a view similar to FIG. 6 showing three
`stents having been placed in the blood vessel in accord
`with another embodiment of the invention.
`FIG. 8 is a view similar to FIGS. 6 and 7 showing
`four stents being placed in a blood vessel in overlapping
`fashion, in accordance with a further embodiment of the
`method of the present invention.
`FIG. 9 is a side elevation of a sheath used in the
`method of the present invention.
`FIG. 10 is a sectional view of the proximal end of the
`sheath showing the stent being placed into the sheath as
`a part of the method of the present invention.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`For the purposes of promoting an understanding of
`the principles of the invention, reference will now be
`made to the embodiment illustrated in the drawings and
`speci?c language will be used to describe the same. It
`will nevertheless be understood that no limitation of the
`scope of the invention is thereby intended, such alter
`ations and further modi?cations in the illustrated de
`vice, and such further applications of the principles of
`the invention as illustrated therein being contemplated
`as would normally occur to one skilled in the art to
`which the invention relates.
`Referring now more particularly to the drawings,
`there is illustrated in FIG. 1 a side elevation of a pre
`ferred embodiment of the stent 9 of the present inven
`tion which includes a length 10 of stainless steel wire
`formed in a closed zig-zag con?guration. The wire is
`closed by a sleeve 11 which is welded to or tightly
`squeezed against the ends of the wire to produce the
`endless con?guration. Referring to FIG. 4, the stent is
`shown in a resiliently compressed ?rst shape wherein
`the straight sections 12 are arranged side-by-side and
`closely adjacent one another.
`The straight sections 12 of the stent are joined by
`bends 13 which are relatively sharp. Thus, in one spe'
`ci?c embodiment of the invention, the bends 13 are at a
`radius of no more than 0.2 cm. This speci?c embodi
`ment of the invention includes wire 10 which is stainless
`steel of 0.018 inch OD. The stent is resiliently expand
`able from the compressed ?rst shape of FIG. 4 into a
`second shape illustrated in FIGS. 1, 2 and 6, wherein
`the straight sections 12 press against the walls of pas
`sageway to maintain the passageway open. FIG. 2
`
`45
`
`55
`
`60
`
`65
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-5
`
`

`
`4
`TABLE I-continued
`Summary of vascular stent placement in ?ve dogs.
`Stent
`Size
`(Number
`Used)
`(5)
`
`Dura
`tion
`'
`month
`
`3
`months
`
`4
`months
`
`5
`months
`
`Vascular Placement
`abdominal aorta (AA) bridging the
`celiac, cranial mesenteric, and right
`renal arteries
`Two placed one inside the other in
`superior vena cava (SVC) at level
`of right atrium
`One placed in the inferior vena
`cava (IVC) bridging both renal veins
`One placed in right jugular 8 cm
`above SVC, and
`two placed one inside the other in left
`jugular 8 cm above SVC
`One placed in AA bridging the
`celiac, cranial mesenteric, and
`right renal arteries
`Two placed one inside the other
`in IVC bridging both
`renal veins
`Two placed one inside the other
`in SVC at level of right
`atrium, and one placed 2.3 cm above
`the right atrium
`One placed in AA bridging the
`cranial mesenteric and both
`renal arteries
`One placed in IVC bridging both renal
`veins
`Four placed one after another in AA
`beginning at diaphragm (T11) and
`ending at L5
`One placed in IVC at level of
`diaphragm
`I
`One placed inside last long stent
`in AA at level of L4-L5
`Two placed one after another in
`IVC between the hepatic and renal
`veins
`
`3.0
`
`(3)
`
`5.5
`
`3.0
`(3)
`
`S 5 (i)
`
`5 5 (5)
`
`3.0
`(3)
`
`5
`
`Dog
`#
`(WI)
`
`10
`
`5
`
`355
`
`25
`
`354
`
`505
`
`35
`
`4,580,568
`3
`shows the end view of the stent in its expanded second
`shape. As illustrated in FIG. 2, the stent has generally a
`circular con?guration or a cylindrical con?guration
`when it is in its second expanded shape.
`In order to practice the method of this invention, the
`stent is compressed into the ?rst shape illustrated in
`FIG. 10 and is placed within a tubular cartridge 15
`(FIG. 10). The cartridge 15 is inserted into the recess 16
`in the adapter 17 of the sheath 20. The stent is then
`advanced through the sheath 20 by means of a ?at
`ended pusher 21. Thus in one speci?c embodiment of
`the invention, the ?at-ended pusher was made of 8
`French polyethylene tubing, although a flat-ended ?exi
`ble metal rod is preferred. When the stent 10 reaches the
`end of the sheath as shown in FIG. 4, the flat-ended
`pusher is held while the sheath is withdrawn as shown
`in FIG. 5. This frees the stent, allowing it to expand and
`hug the vessel wall as shown in FIG. 6. If desired and if
`necessary for the particular situation, further stents can
`be added and can be placed in the blood vessel in the
`same fashion as above described. Thus in FIG. 7, an
`additional two stents are located one longitudinally of
`the ?rst stent in the blood vessel and the other overlap
`ping the ?rst stent while in FIG. 8, four overlapping
`stents are used.
`In tests of the invention, endovascular stents were
`designed and built in two sizes (5.5 cm long><4 cm
`diameter fully expanded; 3.0 cm long><2.5 cm diameter
`fully expanded) from stainless steel wire (0.018 in.)
`formed in a zig-zag pattern. They were placed for vary
`ing periods of time in the jugular vein, inferior vena
`cava and abdominal aorta of ?ve dogs (See Table I
`'below) and evaluated with regard to ease of use, dilat
`ing force, migration, patency, thrombogenicity, and
`local vascular changes.
`Five adult, mongrel dogs (18-27 kg) were used in the
`study. They were anesthetized with i.v. sodium pento
`barbital (Nembutal; 30 mg/kg) and the jugular vein,
`femoral vein, and femoral artery were surgically iso
`lated. An incision was made in the vessels and a 8
`French Te?on sheath containing an 8 French Te?on
`catheter with a taper-tip was inserted and under ?uoro
`scopic monitoring advanced just beyond the area of
`interest. The stent was compressed and placed within a
`45
`Teflon cartridge which ?ts inside the adaptor of the 8
`French sheath. The 8 French catheter was removed, the
`cartridge was placed in the sheath adaptor, and the stent
`was advanced through the sheath with ?at-ended 8
`French polyethylene tubing. When the stent reached
`the end of the sheath, the polyethylene tubing was held
`while the sheath was withdrawn. This freed the stent
`allowing it to expand and hug the vessel wall. In certain
`cases, stents were placed one inside another and/or one
`after another (Table I). Following placement, angio
`grams were made immediately, after one week, and
`then at monthly intervals to document stent position
`and vascular anatomy. The dogs were euthanized at the
`end of the study by exsanguination under deep Nembu
`tal anesthesia, and a complete necropsy was performed.
`
`No dif?culties were encountered in the placement of
`the endovascular stents. They were easy to use and
`could be placed one inside another and/or one after
`another. The expansile strength of the stents was found
`to be dependent on stent length, diameter of stent wires,
`the number of folds in the wire of each stent, and the
`number of stents placed one inside another. Speci?cally,
`expansile force increased with decreased length, in
`creased stent wire diameter, increased number of wire
`folds, and increased number of stents used.
`Angiograms made of the stented vessels showed no
`flow defects, luminal narrowing, or occlusion. Blood
`vessels bridged by the stents remained patent and
`showed no indication of narrowing even after six
`months. No migration was noted with 29 of the 30 stents
`placed. One long stent (5.5 cm) placed alone in the
`inferior vena cava migrated approximately 2 cm crani
`ally during the ?rst week following placement, but no
`further movement occurred and no complications were
`encountered because of this migration.
`Postmortem examinations showed the endothelial
`proliferation occurred around the stents where the
`wires contacted the vessel wall. By four weeks follow
`ing placement, venous stents were almost completely
`(80%) covered by cell growth while aortic stents were
`just beginning (30%) to be incorporated. By 12 weeks,
`all stents were covered witth endothelium where the
`wires contacted the vessel wall. No growth was noted
`on wire segments that bridged side branches even after
`6 months. In addition, no erosion of the vascular walls
`
`60
`
`TABLE I
`Summary of vascular stent placement in ?ve dogs.
`Stent
`Size
`(Number
`Vascular Placement
`Used)
`5.5 cm Two placed one inside the other in
`
`Dog
`#
`(Wt)
`416
`
`65
`
`Dura
`tion
`l
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-6
`
`

`
`20
`
`30
`
`4,580,568
`5
`6
`was noted, and no clot formation was seen on any of the
`maintain the dilatation of a balloon dilated segment of
`stents.
`ureter, urethra, or bowel, aortic dissection, aortic aneu
`Percutaneous expandable endovascular stents can be
`rysm, and localization of a chronic puncture site.
`made of various diameters and lengths from stainless
`While the invention has been illustrated and de
`steel wire formed in a zig-zag pattern. They are easy to
`scribed in detail in the drawings and foregoing descrip
`place percutaneously in veins and arteries and do not
`tion, the same is to be considered as illustrative and not
`require the use of ice water or hot saline as do nitinol
`restrictive in character, it being understood that only
`coils (2, 3). The dilating force of the stent can be con
`the preferred embodiment has been shown and de
`trolled by manipulation of wire size, number of wire
`scribed and that all changes and modi?cations that
`folds, and stent length. Expansion force increases with
`come within the spirit of the invention are desired to be
`larger wire, but so does the size of the collapsed stent
`protected.
`which necessitates use of a larger sheath for placement.
`I claim:
`Increasing the number of wire folds and decreasing the
`1. A stent, comprising:
`stent length also increase the dilating force. Therefore,
`a wire formed into a closed zig-zag con?guration
`including:
`stainless steel vascular stents can be tailor-made with
`regard to length, diameter, and expansion force.
`an endless series of straight sections;
`Multiple stents can be employed depending on the
`a plurality of bends;
`circumstance. If the vessel of interest is longer than one
`said straight sections joined by said bends to form
`stent, several stents can be placed one after another with
`the stent;
`slight overlap at the ends. In addition, if the expansion
`wherein said stent is resiliently depressible into a
`strength of one stent is not sufficient, several stents can
`smaller ?rst shape wherein said straight sections
`be placed one inside another to increase the dilating
`are arranged side-by-side and closely adjacent one
`force at a speci?c point.
`another for insertion into a passageway and said
`Following placement in a blood vessel, the stent
`bends store stress therein; and,
`gradually becomes incorporated into the vascular wall
`wherein said stent is resiliently expandable, by the
`by endothelial proliferation around the wires where
`release of the stress stored in said bends, into a
`they contacted the wall. This is similar to what has been
`second shape wherein said straight sections press
`noted in other studies where metal wire has been placed
`against the wall of the passageway to maintain it
`in the vascular system (2, 3, 4). Radiographic studies
`open.
`indicated that by one week after placement of the stent,
`2. The structure of claim 1 additionally comprising a
`suf?cient endothelial proliferation had occurred to pre
`tubular cartridge having said stent therein, said stent
`vent migration, but during this ?rst week, displacement
`being resiliently depressed into said smaller ?rst shape.
`was possible although not probable. After being in place
`3. The structure of claim 2 additionally comprising a
`for one month, the venous stents were approximately
`sheath having a lumen therethrough, said sheath having
`80% encased by endothelium while the aortic stents
`an adapter recess arranged coaxially with said lumen
`were only about 30% encased. This difference is proba
`and enlarged in size relative to said lumen, and a ?exible
`bly due to the greater ?ow and pressure in the aorta. By
`35
`member having a closed end and having an outer size
`three months, all stent wires contacting the vessel wall
`sufficiently small to ?t within said sheath yet suffi
`were completely encased in endothelium. This incorpo
`ciently large to push said stent out of said sheath.
`ration into the vascular wall reduces thrombogenicity
`4. The stent of claim 1 wherein said wire is stainless
`(3), but no clot was found even on the bare wires after
`steel of 0.018 inch CD.
`6 months. No cell growth was noted on any of the wire
`5. The stent of claim 4 wherein said stent in its second
`segments not in contact with- the vascular wall, e.g.,
`shape is 5.5. cm long and 4 cm in diameter.
`where stents bridged side branches. This observation
`6. The stent of claim 4 wherein said stent in its second
`corresponds with previous reports on the use of en
`shape is 3.0 cm long and 2.5 cm in diameter.
`dovascular stainless steel wires (4). Therefore, the stents
`7. The stent of claim 4 wherein said bends are rela
`can bridge other vessels without occluding them or
`tively sharp and are at a radius of no more than 0.2 cm.
`producing luminal narrowing at the branch points. This
`8. A method for inserting a stent which comprises:
`has not been reported for other types of endovascular
`compressing a stent including a resilient wire formed
`stents (2, 3). Thus it appears that the stainless steel stents
`in a closed zig-zag con?guration into a ?rst shape
`can be placed anywhere in the vascular system that will
`wherein the zig-zag con?guration includes side-by
`accomodate them. No luminal narrowing was noted in
`side closely adjacent straight sections joined by
`the stented vessels even after six months. This differs
`bends with a stress therein;
`from the nitinol endovascular stents which have been
`moving said compressed wire stent into a sheath;
`shown to product luminal narrowing within 4 weeks
`locating the distal end of the sheath in a passageway
`due to ?brin deposition on the stent wires (1, 2, 3).
`with the compressed wire within the distal end of
`No clot formation was found on any of the stents at
`the sheath;
`the time they were removed. This is similar to previ
`removing the sheath from the passageway while
`ously reported results (2, 3). No vascular erosion was
`holding the stent in place whereby the stress in the
`seen probably because the vessels were normal and able
`to expand thus reducing the force of the stent wires
`stent causes it to expand in the passageway to hold
`against the vacular wall.
`the passageway open and enlarged.
`Results from this evaluation indicate that these stents
`9. The method of claim 8 wherein more than one
`60
`should ?nd various clinical applications. These may
`stent is put in the passageway by said compressing,
`include re-establishment of flow in veins compressed by
`moving, locating and removing steps, said more than
`one sheath being overlapping.
`neighboring tumor (superior vena cava syndrome),
`maintenance of vascular patency after percutaneous
`10. The method of claim 8 wherein more than one
`balloon dilations, and correction of incomplete, long,
`stent is put in the passageway by said compressing,
`irregular vascular stenosis. In addition, it may be possi
`moving, locating and removing steps, said more than
`ble to use these stents in other systems such as the respi
`one stent being spaced longitudinally of the passage
`ratory, biliary, and urinary tracts to reinforce collapsing
`way.
`structures from extrinsic compression from neoplasma,
`
`* it
`
`45
`
`50
`
`55
`
`65
`
`it
`
`1‘
`
`ll
`
`W.L. Gore & Associates, Inc.
`Exhibit 1021-7