Page 1 of 15
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`EDWARDS LIFESCIENCES EX. 1120
`Edwards Lifesciences v. Boston Scientific Scimed
`U.S. Patent No. 6,915,560
`
`

`
`Page 2 of 15
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`US 7,892,201 B1
`Page 2
`
`11/1995 Crocker et al.
`5,470,313 A
`12/1995 Trotta
`5,478,320 A
`2/1995 Wang 6131.
`5,490,339 A
`3/1995 Wang 6131.
`5,495,275 A
`3/1995 S11ap1ande1a1.
`5,493,233 A
`3/1996 Saab
`5,499,973 A
`3/1996 Euteneuer
`5,499,980 A
`3/1996 Teristein
`5,499,995 A
`3/1996 Anderson etal.
`5,500,180 A
`3/1996 Wange1a1.
`5,500,131 A
`4/1996 Wange1a1.
`5,512,051 A
`5/1995 Spenceret 31.
`5,519,172 A
`6/1996 Sega1
`5,527,232 A
`5/1995 N0m1e1a1.
`5,529,320 A
`3/1997 Marshall et al.
`5,609,605 A
`3/1997 71101136131.
`5,513,979 A
`4/1997 T1003
`5520549 A
`6/1997 Sharmon etal.
`5,641,373 A
`2/1998 Krausetal. ............ .. 604/509
`5,718,680 A *
`3/1998 Daneshvar .... ..
`. 604/96.01
`5,728,066 A *
`6/1998 Ravenscroft etal.
`606/194
`5,766,201 A *
`
`5,843,116 A * 12/1998 Crockeretal.
`606/192
`5,868,704 A
`2/1999 Campbell et al.
`604/96
`5,919,163 A *
`7/1999 Glickman
`. 604/101.05
`6,139,570 A * 10/2000 Saadatetal.
`607/105
`.
`6,312,405 131*
`11/2001 Meyer et al.
`........... .. 604/96.01
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`GB
`W0
`W0
`W0
`W0
`W0
`W0
`
`0 540 858
`1566674
`90/14054
`94/02185
`95/05555
`96/14895
`97/02791
`99/02212
`
`5/1993
`5/1980
`11/1990
`2/1994
`2/1995
`5/1996
`1/1997
`1/1999
`
`* cited by examiner
`
`U.S. PATENT DOCUMENTS
`
`4,896,669 A
`4,946,464 A
`4,955,899 A
`5,066,298 A
`5,071,609 A
`5,087,244 A
`5,112,304 A
`5,116,318 A
`5,137,512 A
`5,152,782 A
`5,171,297 A
`5,192,296 A
`5,201,706 A
`5,211,654 A
`5,213,576 A
`5,226,880 A
`5,236,659 A
`5,254,090 A
`5,256,143 A
`5,286,254 A
`5,290,306 A
`5,330,429 A
`5,338,299 A
`5,342,305 A
`5,348,538 A
`5,358,486 A
`5,358,516 A
`5,366,472 A
`5,370,618 A
`5,403,340 A
`5,411,479 A *
`5,415,636 A
`5,425,710 A
`5,429,605 A
`5,456,661 A
`5,458,568 A
`5,466,252 A
`
`1/1990 Bhate etal.
`8/1990 Pevsner
`9/1990 De1C0rnaeta1.
`11/1991 Hess ........................ .. 606/194
`12/1991 T116131,
`2/1992 W01ins1<yeta1~
`5/1992 Bar10We1a1~
`5/1992 Hillstead
`8/1992 Burnsetal.
`10/1992 Kowligiet al.
`12/1992 Barlowetal.
`3/1993 Bhate etal.
`4/1993 Noguchi et a1,
`5/1993 Kaltenbach
`5/1993 Abiuso et al.
`7/1993 Martin
`8/1993 Pin0hu1<e1a1~
`10/1993 Lombardi 6131,
`10/1993 Mi11ereta1~
`2/1994 Shaplandetal,
`3/1994 T101111 6131,
`7/1994 Noguchletal,
`8/1994 Bar10W
`8/1994 Sh0n1<
`9/1994 Wang etal.
`10/ 1994 Saab
`10/1994 Myers etal.
`11/1994 Hillstead
`12/1994 Leonhardt
`4/1995 Wang etal.
`5/1995 Bodden ............... .. 604/101.03
`5/1995 Forman
`6/1995 Khairetal.
`7/1995 Berndetal.
`10/1995 Narciso, Jr.
`10/1995 Racchinietal.
`11/1995 Soukup et al.
`
`Page 2 of 15
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`U.S. Patent
`
`Feb. 22, 2011
`
`Sheet 1 of5
`
`US 7,892,201 B1
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`Page 3 of 15
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`Page 3 of 15
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`

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`U.S. Patent
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`Feb. 22, 2011
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`Sheet 2 of5
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`US 7,892,201 B1
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`F“; 4
`
`,, 7.1,
`
`
`
`H
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`/2.
`
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`36
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`(7,.
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`Page 4 of 15
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`Page 4 of 15
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`

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`U.S. Patent
`
`Feb. 22, 2011
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`Sheet 3 of5
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`US 7,892,201 B1
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`/:/c—.. 8
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`‘+2
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`U.S. Patent
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`Feb. 22, 2011
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`Sheet 4 of5
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`US 7,892,201 B1
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`F76. IO
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`/2 P,/«'9
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`/-7G./ 39‘
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`‘$8
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`Page 6 of 15
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`Page 6 of 15
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`

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`U.S. Patent
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`Feb. 22, 2011
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`Sheet 5 of5
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`US 7,892,201 B1
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`Page 7 of 15
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`Page 7 of 15
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`

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`US 7,892,201 B1
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`1
`BALLOON CATHETER AND METHOD OF
`MOUNTING SAME
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to improved balloon catheter
`devices, and methods of making the same.
`2. Description of Related Art
`Balloon catheter devices are commonly used for a wide
`variety of medical procedures today, including temporarily
`occluding blood or other fluid flow, re-shaping of blood ves-
`sels or other body conduits, removing plaque or other
`obstructions from vessels, and/or delivering or positioning
`devices within vessels, such as intraluminal stent or stent-
`graft devices. With on-going advances in minimally invasive
`medical procedures, such balloon devices continue to grow in
`popularity and in scope of possible uses.
`Traditionally, balloon devices have taken one of two gen-
`eral forms—angioplasty balloons and embolectomy bal-
`loons. Angioplasty balloons have generally been constructed
`from relatively stiff material, such as poly(ethylene tereph-
`thalate) (PET), which can be safely inflated to relatively high
`internal pressures (such as on the order of 10ATM (1.0 MPa)
`or more). These balloons generally inflate rapidly to a given
`maximum diameter and will undergo minimal additional
`enlargement upon introduction of additional pressure (until
`they burst under extreme pressures). These balloons are typi-
`cally used where high pressure is desired, such as to fracture
`and/or compact hard plaque in a blood vessel or to deliver
`balloon expandable devices, such as stents. One drawback
`with stiff angioplasty balloons, however, is that upon defla-
`tion they tend to become a crinkled, flattened mass that have
`dimensions significantly larger than their initial introduction
`diameter—making them more diflicult to remove than to
`initially introduce. Additionally, these flattened devices in
`many cases cause adverse interactions between themselves
`and the devices with which they are conjunctly used.
`By contrast, embolectomy balloons are normally con-
`structed from a highly elastomeric material, such as latex,
`which will enlarge steadily in diameter with a steady increase
`in internal pressure. These balloons typically are governed by
`the volume of fluid/liquid used to inflate them rather than an
`operating pressure, have much lower operating pressures
`(such as, typically on the order of about 2 ATM (203 kPa) or
`less) and they tend to continue to grow in diameter upon
`further introduction of pressure until they ultimately burst.
`These balloons are typically used in embolic procedures
`where soft material is repositioned in a vessel. Additionally,
`the balloon can be formed from a tacky material such as latex
`that can be used to adhere to soft plaque, thrombus or other
`undesirable material within a vessel and then withdrawn to
`
`10
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`15
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`20
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`25
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`30
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`remove the undesirable material. Although these balloons
`have low operating pressures, they do tend to deflate to diam-
`eters almost identical to their initial introduction diameters—
`
`55
`
`making them very easy to remove.
`It has been a long desired goal to develop a balloon that can
`withstand the very high pres sures required for angioplasty but
`also has the inflation and deflation characteristics of an embo-
`
`lectomy balloon. The combination of these properties was
`achieved with the invention of the balloon devices described
`
`in U.S. Pat. Nos. 5,752,934 and 5,868,704 to Campbell, et al.,
`and U.S. patent application Ser. No. 08/858,309 to Campbell,
`et al. These patents describe several important advances in
`balloon catheter constructions, including how to construct
`high pressure balloons from expanded polytetrafluoroethyl-
`ene (PTFE) and an elastomer so as to exhibit steady growth
`
`2
`
`with increasing pressure up to a pre-determined maximum
`diameter and then readily compact to virtually their initial
`introduction diameters for easy removal.
`The Campbell et al. patents teach how to form a tubular
`sleeve from expanded PTFE tape and then coat the sleeve
`with an elastomer. The sleeve is then mounted on a catheter
`
`shaft in a manner that allows it to contain expansion liquid
`(either by mounting the sleeve over an expandable bladder
`(e.g., a latex or PET balloon) or by rendering the sleeve
`liquid-tight so as to allow it to serve as the bladder itself). The
`result is a unique balloon that combines high-pressure per-
`formance with compaction to near initial introductory diam-
`eter following inflation and deflation. Balloons made in
`accordance with the Campbell et al. patents have excellent
`performance characteristics and are particularly suitable for
`delivery and/or deployment of balloon expandable devices,
`such as intravascular stents.
`
`Despite the excellent performance characteristics of the
`Campbell et al. balloons, it is believed that further improve-
`ments are desirable in the balloons and their mounting tech-
`niques to make them easier to mount on catheter shafts.
`Further, it is believed that further improvements in balloon
`performance can be achieved by modifying the mounting
`techniques, such as to provide a controlled failure mecha-
`nism.
`
`SUMMARY OF THE INVENTION
`
`The present invention is an improved method of forming
`and mounting a distensible balloon catheter, and sleeves used
`to construct such balloons. One embodiment ofthe method of
`
`the present invention comprises forming a distensible balloon
`sleeve with non-distensible ends. The sleeve is mounted on
`
`the catheter shaft at the non-distensible ends while retaining
`the distensibility of the balloon as a whole. This construction
`is easier to mount and more reliable in operation than previ-
`ous mounting methods. Alternatively or additionally, the bal-
`loon may be mounted to the catheter shaft using non-disten-
`sible tape that also retains the distensibility of the operative
`portion of the balloon. The present invention is particularly
`adapted for use with expanded polytetrafluoroethylene
`(PTFE) balloons, such as those described in U.S. Pat. Nos.
`5,752,934 and 5,868,704 to Campbell, et al.
`The mounting techniques of the present invention are fur-
`ther readily adapted to include other beneficial properties,
`such as inclusion of controlled failure mechanisms. These
`
`and other benefits ofthe present invention will be appreciated
`from review of the following description.
`
`DESCRIPTION OF THE DRAWINGS
`
`The operation of the present invention should become
`apparent from the following description when considered in
`conjunction with the accompanying drawings, in which:
`FIG. 1 is a side elevation view of a balloon device made in
`
`60
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`65
`
`accordance with the present invention shown, in an inflated
`orientation;
`FIG. 2 is a side elevation view ofthe balloon device of FIG.
`1, shown in a deflated orientation;
`FIG. 3 is an exploded side elevation view of a stepped end
`of a catheter shaft, an inner member, and a tubular sleeve used
`to construct a balloon in accordance with the present inven-
`tion;
`FIG. 4 is an enlarged side elevation view of a sleeve
`mounted over a stepped end of a catheter shaft;
`
`Page 8 of 15
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`Page 8 of 15
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`

`
`US 7,892,201 B1
`
`3
`FIG. 5 is the sleeve and stepped end of FIG. 4 with a tape
`being wrapped around the sleeve to help attach it to the
`stepped end;
`FIG. 6 is the sleeve and stepped end of FIG. 5 with the tape
`completely mounted over the sleeve on the end ofthe catheter
`shaft;
`FIG. 7 is a three-quarter elevation view of a further
`improved sleeve for use with the present invention;
`FIG. 8 is a three-quarter elevation view of an apparatus
`suitable for forming the sleeve of FIG. 7;
`FIG. 9 is an enlarged three-quarter elevation view of a
`modified end of a sleeve for use with the present invention, the
`sleeve being provided with slits for providing controlled fail-
`ure ruptures with the present invention;
`FIG. 10 is a side elevation view of a balloon device made in
`
`accordance with the present invention incorporating another
`embodiment of means to provide controlled failure with the
`present invention;
`FIG. 11 is a side elevation view of the balloon device of
`
`FIG. 10 with the balloon over-inflated, which partially dis-
`lodges its mounting tape so as to uncover and begin to active
`the means to provide controlled failure ruptures;
`FIG. 12 is a side elevation view of the balloon device of
`
`FIG. 11, showing the balloon deflating as a result of the
`controlled failure mechanism;
`FIG. 13 is a partial longitudinal cross-section view of
`another embodiment of a balloon device of the present inven-
`tion; and
`FIG. 14 is a partial longitudinal cross-section view of yet
`another embodiment of a balloon device of the present inven-
`tion.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`The present invention is directed to improved methods of
`mounting a balloon such as that described in U.S. Pat. Nos.
`5,752,934 and 5,868,704 to Campbell, et al. and U.S. patent
`application Ser. No. 08/858,309 to Campbell et al. (hereafter
`“Campbell et al. patents”), all incorporated by reference.
`The Campbell et al. patents describe improved balloons
`that combine the ability to safely and predictably achieve high
`operating pressures with the ability to be introduced at a small
`initial profile, be fully inflated, and then deflated to nearly the
`same initial profile for ease ofremoval. The preferred balloon
`devices of the Campbell et al. inventions employ multiple
`wraps using a porous expanded polytetrafluoroethylene
`(PTFE) tape, such as one made in accordance with U.S. Pat.
`Nos. 3,953,566 and 4,187,390, incorporated by reference,
`combined with an elastomeric material, such as a polyure-
`thane, so as to seal the porous structure ofthe expanded PTFE
`and render it liquid-tight. The resulting structure can be
`formed into a tube and then mounted onto a catheter shaft,
`such as through adhesion using various adhesives and meth-
`ods. In particular, the mounting methods contemplated by the
`Campbell et al. patents are described in U.S. Pat. No. 5,752,
`934, for example, at: col. 9, lines 25-34; and col. 10, lines
`38-44; and in U.S. Pat. No. 5,868,704, for example, at: col.
`10, line 60, to col. 11, line 3; col. 12, lines 4-13; and col. 14,
`line 17, to col. 15, line 8.
`While these previous mounting methods function quite
`well, it has been determined that significant improvements
`are possible in increasing the speed and ease of mounting of
`tubular structures onto a catheter shaft in order to form a
`
`catheter balloon device. Referring to FIGS. 1 through 3, the
`present invention comprises an inflatable balloon 10, formed
`from a tubular sleeve 12 that is mounted onto a catheter shaft
`14 and an inner member 16. The balloon 10 is introduced in a
`
`4
`
`compacted, deflated configuration 18, such as that shown in
`FIG. 2, and then distended to a fully enlarged, inflated con-
`figuration 20, such as that shown in FIG. 1.
`The catheter shaft 14 preferably has a reduced diameter
`over a segment 22 adapted to receive the sleeve 12 so that a
`smooth transition 24 is formed between the catheter shaft 14
`
`and the balloon following mounting, as is shown in FIG. 2.
`FIG. 3 illustrates a beveled landing 26 that performs this
`function. By way of example, for a catheter shaft with an
`outer diameter of about 0.5 to 3 .5 mm and a sleeve with a wall
`
`thickness of about 0.1 to 0.5 mm, a suitable landing 26 might
`have a diameter of about 0.5 to 2 mm. The difference in
`dimensions between the wall thickness and the reduced diam-
`
`eter of the landing can be accounted for by the addition of
`adhesive and a tape wrap, as is explained below. The length of
`the landing 26 in this embodiment might range from about 1
`to 5 mm.
`The sleeve 12 includes a first end 28 and a second end 30.
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`10
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`15
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`The first end 28 of the sleeve 12 is attached to the landing 26.
`The second end 30 of the sleeve is attached to the inner
`
`member 16 at its distal (that is, “leading”) end 32. The sleeve
`12 should be constructed from a distensible material, such as
`an elastomer (e.g., silicone, latex, polyurethane, or from a
`composite of expanded PTFE and elastomer as described
`above) that allows the sleeve to be inflated and deflated within
`normal operating pressures without causing permanent
`unfolding or deforming of the balloon material. By the term
`“distensible,” it is intended to define a balloon material with a
`structure that will change in one or more dimensions upon
`introduction of distention force. Preferably, the balloon mate-
`rial will compact to most or all of its previous dimensions
`upon removal of the force. In this manner, the balloon will
`deflate to a “wingless” diameter following inflation, instead
`of deflating to a flattened, “winged,” structure that may be
`hard to remove, such as that formed by a conventional PET
`balloon.
`
`It has been determined, however, that distensible material
`does not always mount successfully to a catheter shaft since
`the material may tend to separate from the catheter shaft
`and/or undergo damage during inflation. To address this prob-
`lem, the present invention treats the ends 28, 30 of the sleeve
`12 to render them non-distensible. By the term “non-disten-
`sible,” it is intended to define a balloon material with a struc-
`ture that is significantly less compliant under distention force
`than a distensible main body of the balloon and, preferably,
`material that will undergo little or no change in dimensions
`upon introduction of distention force.
`As is explained in greater detail below, the ends may be
`rendered non-distensible through a variety of methods,
`including by: over-wrapping the ends with non-distensible
`material, such as a tape; attaching non-distensible structures;
`coating or permeating the ends with a non-distensible mate-
`rial, such as a fluorinated ethylene propylene (FEP) or
`cyanoacrylate ester; and/or modifying the structure of the
`material to render it non-distensible, such as through heat
`(including laser) treatment. Other possible methods of ren-
`dering the ends non-distensible may include insert molding
`and injection molding.
`Once the ends 28, 30 have been rendered non-distensible,
`the sleeve 12 may be readily mounted on the catheter to form
`a liquid-tight seal through a number ofpossible ways, such as
`through, but not limited to, application or tape, glue, heat
`bonding, mechanical swaging, or some combination oftwo or
`more of these mounting methods. The preferred method of
`mounting is described below with reference to FIGS. 4
`through 6.
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`Page 9 of 15
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`US 7,892,201 B1
`
`5
`FIG. 4 illustrates a sleeve 12 positioned over a landing 26
`on a catheter shaft 14. The sleeve 12 and landing 26 should be
`proportioned so that the sleeve fits closely over the landing,
`with a clearance 32 of about 0.06 mm or less. Preferably, the
`sleeve 12 fits snugly over the landing 26, with virtually no
`clearance, so as to resist separation between the sleeve 12 and
`the catheter shaft 14 upon application of tension on the sleeve
`12. An adhesive may be applied to the landing 26 (and/or the
`interior of the sleeve 12) prior to mounting on the shaft to aid
`in forming a bond. Suitable adhesives include: UV cure adhe-
`sive, cyanoacrylate ester, epoxy, polyurethane, silicone, and
`melt adhesives such as fluorinated ethylene propylene (FEP).
`The preferred adhesive is a thin coating ofcyanoacrylate ester
`adhesive applied to the full surface of the landing immedi-
`ately prior to placing the sleeve 12 on the catheter shaft 14.
`Once the sleeve 12 is positioned on the catheter shaft 14, a
`tape 34 is wrapped around the end 28, as is shown in FIG. 5.
`Tension is preferably applied on both ends 36, 38 of the tape
`as it is wrapped into place. To hold the tape in place, an
`adhesive should be applied between the wrap layers, such as
`by applying a drop of cyanoacrylate ester between the layers
`during the wrapping. Once the tape 34 is completely wrapped
`around the end 28 to snugly compress the sleeve against the
`landing, adhesive should be applied to the ends 36, 38 to
`secure the ends in place, as is shown in FIG. 6.
`The tape 34 is preferably formed from a material that is
`essentially non-distensible in its longitudinal direction. A
`preferred tape comprises a tape of expanded PTFE having a
`width of about 1 to 10 mm, a thickness of about 0.01 to 0.02
`mm, and a matrix tensile strength in its longitudinal direction
`of about 50 to 150 kpsi (345 to 1034 MPa) measured using a
`strain rate of 100% per minute.
`A number of alternative mounting techniques can be
`employed without departing from the present invention. For
`example, instead of applying a separate adhesive to the tape
`during the wrapping process, adhesive may be applied to the
`tape before wrapping and later activated (such as through
`application of heat, ultra-violet or infared light, solvent acti-
`vation, pressure activation, etc.). One method is to apply a
`coating of a thermoplastic polymer, such as polyurethane, to
`the tape prior to wrapping and then applying heat to the
`wrapped end to melt the polyurethane coating and bond the
`wrapping into place. Mounting can also be achieved by
`directly welding the tape, the sleeve material itself (with or
`without a tape wrap), and/or the catheter material into a sealed
`bond between the catheter and the sleeve, whether by appli-
`cation of heat, solvent, or other means.
`The choice of materials should be selected so that bonding
`may be achieved without adversely affecting component per-
`formance. For example,
`if a catheter shaft of PEBA is
`employed with a composite balloon of expanded PTFE and
`polyurethane, the bonding melt temperature should be about
`160° and maintained below 180° C.
`
`Other alternative mounting techniques may include: com-
`pression fitting (“swaging”); solvent welding, ultrasonic
`welding; laser welding; radio frequency (“rr”) welding; etc.
`As has been noted, the ends 28, 30 of the sleeve 12 are
`preferably rendered non-distensible prior to mounting. To
`accomplish this, a number of techniques can be applied. FIG.
`7 illustrates a sleeve 12 that has had a non-distensible tape 40
`applied around its ends 28, 30. One effective technique is to
`place the sleeve on a mandrel and then apply the tape in the
`manner previously described with respect to the sealing tech-
`nique described above with respect to FIGS. 4 through 6. The
`mandrel may then be removed once the ends have been prop-
`erly treated.
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`6
`Another technique is to heat treat the ends 28, 30 to reduce
`the material’ s distensiblity and profile in the end regions. One
`preferred method is to employ an oven 42 with a contractible
`iris 44 as is shown in FIG. 8. To treat a sleeve 12 of expanded
`PTFE and elastomer, as previously described, the oven 42
`should be set to about 70 to 165° C. Again, the sleeve 12
`should be temporarily mounted on a mandrel to hold it in a
`proper orientation during the heat-treating process. The iris
`44 is closed around the sleeve and compressed under a com-
`pressive force for about 1 to 30 seconds.
`Alternative methods for rendering the ends ofthe sleeve 12
`non-distensible include addition of metal bands, shrink tub-
`ing, plastic bands, wire wrap, use ofnon-distensible materials
`at the ends of the balloon, etc. Profile reduction may also be
`achieved through internal material removal, such as through
`grinding, solvent, or laser removal, or through material thick-
`ness reduction at the ends by thinning through relative elon-
`gation (e.g., stretching) of the ends. Additionally, distensible
`material may be removed from the ends, with other, non-
`distensible, materials possibly being substituted in that area.
`Formed in this manner, a balloon made in accordance with
`the present invention retains all of the properties previously
`described with respect to the previous Campbell et al. bal-
`loons, while being faster, easier, and more reliable to mount
`on a catheter shaft.
`
`The present invention may be further refined to provide
`other beneficial properties. For example, the mounting tech-
`nique may be modified to provide for controlled failure if the
`balloon is ever accidentally over-inflated to a bursting pres-
`sure. One concern with any balloon material is that if the
`balloon is over-pressurized and bursts in a patient’s body,
`small fragments of the burst balloon may be difficult or
`impossible to recover—potentially leading to very serious
`health problems for the patient. In this respect, it would be
`desirable to provide a mechanism for a balloon to fail in a
`completely controlled manner if over-inflation ever occurs so
`that all fragments of the balloon remain together following
`rupture or to ensure failure of another sub-system of the
`device prior to rupture of the actual balloon material.
`One such method of accomplishing controlled failure is to
`form one or more apertures through the sleeve 12 that will
`release pressure prior to the balloon bursting—causing a pre-
`dictable and controlled pressure release that does not result in
`fragment formation. FIG. 9 illustrates one such method of
`treating the sleeve 12 by forming one or more slits 46a, 46b in
`at least one ofthe ends 28 (and/or 30) that will be sealed under
`mounting tape 34 prior to failure but will uncover once the
`balloon becomes over-expanded. The slits may be formed at
`any point during construction, but are most easily applied
`after the ends have been rendered non-distensible. This pro-
`cess of progressively exposing the slit is shown in FIGS. 10
`through 12.
`Shown in FIG. 10 is another embodiment of a weakened
`section, in this instance a small oval hole 48 formed in end 30.
`During normal operation, the hole 48 is completely concealed
`under the mounting tape 34. However, ifthe balloon 10 is ever
`over-inflated, as is shown in FIG. 11, the tape 34 will fold
`toward distal end 52, progressively uncovering hole 48. Once
`the hole 48 is uncovered, the inflation liquid, causing exces-
`sive pressure in the balloon, will begin leaking through the
`hole 48. In this manner the balloon can be prevented from
`exploding and fragmenting—allowing the failed balloon to
`be removed in one piece.
`Other methods of providing controlled failure of the bal-
`loon include: weakening the wall (without fully penetrating
`it) through use of a cut through only part of the sleeve wall;
`weakening the wall in a predetermined location by altering its
`
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`US 7,892,201 B1
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`7
`structure through use of a laser, heat, mechanical means, or
`chemical reaction; reinforcing the sleeve in all but certain
`segments that are intended to fail (such as through a coating
`process); controllably degrading the elastomeric component
`so that failure constitutes leaking through the balloon mate-
`rial rather than rupture; selecting an elastomer that fails at a
`desired failure diameter; etc.
`Without intending to limit the present invention to the
`specifics described hereinafter, the following examples illus-
`trate how the present invention may be made.
`
`Example 1
`
`A 7.62 mm wide length of porous expanded PTFE film is
`wrapped onto a 4.0 mm diameter metal mandrel at a pitch of
`about 2.54 mm per mandrel revolution so that about 3 over-
`lapping layers cover the mandrel. Following this wrap,
`another 3 layers of the same film are applied over the first 3
`overlapping layers, using the same pitch but in the opposite
`direction. This method of single-pass application is repeated
`a total of six times, so that finally, a total of 18 helical over-
`lapping layers are applied onto the mandrel.
`With the wrapping complete, the mandrel and overlying
`expanded PTFE film are placed in an air convection oven set
`at about 380° C. for about 18 minutes to heat-bond the adja-
`cent layers of film, then removed and allowed to cool. The
`resulting 4.0 mm inner diameter film tube formed from the
`helically wrapped layers of film is then removed from the
`mandrel.
`
`The film tube is then tensioned longitudinally, simulta-
`neously reducing in diameter and lengthening until it reaches
`approximately 4.5 times its length while on the 4.0 mm man-
`drel post heat-bonding. The tube is then coaxially fitted over
`a 3.8 mm diameter metal mandrel. This coaxial fitting is done
`carefully, ensuring that the diameter increase experienced by
`the film tube occurs in a consistent manner, and that the tube
`is not damaged. With the coaxial fitting complete, the film
`tube is measured to be approximately twice its length while
`on the 4.0 mm mandrel post heat-bonding. The film tube is
`then carefully removed from the 3.8 mm mandrel.
`Removed from the 3 .8 mm mandrel, a knot is created at one
`end of the film tube while a 3.0 mm metal tube is inserted
`
`coaxially into the other end of the film tube. The metal tube
`and the overlying film tube are then submerged into a 4% (4
`g per 100 ml) solution of TT-1070A TECOTHANE® resin
`manufactured by Thermedics Inc. (Woburn, Mass.) in tet-
`rahydrofuran manufactured by J. T. Baker (Phillipsburg,
`N.J.). The metal tube and the overlying film tube are situated
`such that the knotted end of the film tube is submerged com-
`pletely, but the open end of the film tube and the open end of
`the metal tube are not. In this manner, the TECOTHANE®
`solution is in direct contact with the outside of the film tube
`
`for approximately one minute. The metal tube and the film
`tube are then removed from the TECOTHANE® solution,
`and the film tube (still wet with solution) is then carefully
`removed from the metal tube and allowed to dry at ambient
`temperature for approximately 30 minutes. Care is taken to
`avoid any folding of the film tube.
`Next, the film tube is placed within an INSTRON® tensile
`test machine equipped with flat-faced jaws, and tensioned
`longitudinally at a rate of 200 mn1/min until a load of 9.5 kg
`is achieved. Once this tension is achieved, the film tube is held
`at fixed length and subjected to heat from a hot air gun until
`the load indicator on the INSTRON® tensile testing machine
`reads 2.3 kg. The heat is such that it accelerates the force
`declination, but does not affect the TECOTHANE® material
`adversely. The upper jaw of the testing machine is then
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`opened, and a 0.43 mm stainless steel wire is fitted coaxially
`within the longitudinally pulled film tube. The upper jaw is
`positioned such that it fully engages the film tube, but not the
`resident wire, and closed. The film tube is then subjected to
`heat from the hot air gun and tensioned longitudinally again,
`at a rate of 200 mm/min, until a load of 8.7 kg is achieved.
`Once this tension is achieved, the film tube is again held at
`fixed length, with continued heat from the hot air gun, until
`the load indicator on the INSTRON® tensile testing machine
`reads 3.5 kg. The ends of the film tube are then secured to the
`wire to prevent longitudinal shrinkage, and the film tube and
`wire assembly are removed from the tensile test machine.
`Additional expanded PTFE film is then helically applied to
`the outer surface of the film tube to inhibit wrinkling in the
`subsequent step. The securing means between the film tube
`and the underlying wire are removed. The tube is then com-
`pressed longitudinally, reducing the tube length to approxi-
`mately 0.6 of the length just prior to this compression step.
`Care is taken to ensure a high degree of uniformity of com-
`pression along the length of the tube. The additional outer
`film is then removed from the longitudinally compressed film
`tube, and the film tube is cut at each end to expose approxi-
`mately 2.0 cm of the wire underneath.
`A blunt tipped needle with a female luer connector at one
`end, approximately 36 mm long, having 1.27 mm outer and
`0.84 mm inner diameter, is inserted coaxially between the
`film tube and the 0.43 mm wire. A vacuum pump is then
`connected, by means of a male luer, to the female luer
`equipped needle at the end of the film tube, and the lumen of
`the film tube, via the needle, is subjected to negative pressure.
`The entire assembly consisting of the wire, film tube, and
`needle is then attached to a variable speed linear slide.
`The slide is used to dip the assembly, with the vacuum
`pump running into a 10% (10 g per 100 ml) solution of
`TT- 1070A TECOTHANE® resin manufactured by Thermed-
`ics Inc. (Woburn, Mass.) in tetrahydrofuran manufactured by
`J. T. Baker (Phillipsburg, N.J.). The assembly is dipped to the
`point where about 5 mm of the film tube, covering the blunt
`needle, is within the solution. The assembly remains within
`the solution for approximately 30 seconds, after which the
`linear slide, set at a speed of 3.7 mn1/sec is used to remove the
`assembly. The 3.7 mn1/sec speed is chosen because it yields a
`continuous, uniform coating of solution on the surface of the
`film tube. Once completely removed from the solution, the
`assembly is disconnected from the linear slide and the
`vacuum pump, and allowed to dry at ambient temperature for
`approximately 30 minutes. Care is taken to keep the assembly
`oriented in a vertical position to maintain the uniformity of
`the TECOTHANE® coating.
`With the solution dry, the film tube is left with a thin coating
`of TT-1070A TECOTHANE® material on its outer surface.
`
`The portion of the film tube covering the blunt needle (along
`with the needle itself) is removed from the rest of the film
`tube. Likewise, a portion approximately 1.0 cm long is
`removed from the other end of the film tube. The remaining
`film tube portion is then carefully removed from the coaxially
`fitted 0.43 mm wire. Next, a small bevel cut is made at one end
`ofthe film tube. A 0.71 mm wire is used to push the point of
`the beveled end within the lumen of the coated film tube. The
`
`same wire is then carefully used to continue pushing the
`beveled end further and further within the lum