(12) United States Patent
`DiCaprio et al.
`
`USOO672671.4B2
`(10) Patent No.:
`US 6,726,714 B2
`(45) Date of Patent:
`Apr. 27, 2004
`
`(54) STENT DELIVERY SYSTEM
`(75) Inventors: Fernando DiCaprio, St. Paul, MN
`(US); Jan D. Seppala, Maple Grove,
`MN (US); Kyle P. Taylor, Brooklyn
`Park, MN (US)
`
`(73) Assignee: SciMed Life Systems, Inc., Maple
`Grove, MN (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 236 days.
`
`(*) Notice:
`
`(21) Appl. No.: 09/925,385
`1-1.
`(22) Filed:
`Aug. 9, 2001
`(65)
`Prior Publication Data
`US 2003/0033000 A1 Feb. 13, 2003
`(51) Int. Cl.................................................... A61F 2/06
`(52) U.S. Cl. ...................................................... 623/1.11
`(58) Field of Search ............................... 623/1.11, 1.23;
`604/148, 508, 509, 510; 606/108, 191,
`194, 192, 198, 195
`
`(56)
`
`References Cited
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`
`Primary Examiner Michael J. Milano
`S.) Attorney, Agent, or Firm Vidas, Arrett&Steinkrays
`
`ABSTRACT
`(57)
`This invention relates to catheters used for delivering medi
`cal devices. The catheter incorporates Sleeves which aid in
`containing the medical device on the catheter, wherein the
`sleeves have portions comprising high modulus material to
`aid in the function of the sleeves.
`
`23 Claims, 6 Drawing Sheets
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`IPR2020-00126/-127/-128/-129/-130/-132/-134/-135/-136/-137/-138
`
`Medtronic Ex-1803
`Medtronic v. Teleflex
`
`

`

`US 6,726,714 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
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`EP
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`EP
`O 442 657
`8/1991
`EP
`O457 456
`11/1991
`EP
`O540858
`5/1993
`EP
`O 420 488 B1
`7/1993
`EP
`O 553 960 A1
`8/1993
`EP
`O 553 960
`8/1993
`EP
`O 582870
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`EP
`O 627 201
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`EP
`O 699 451
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`EP
`O 707837
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`EP
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`WO
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`WO
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`WO
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`WO 96/03092
`2/1996
`WO
`WO 96/04951
`2/1996
`* cited by examiner
`
`
`
`Page 2
`
`

`

`U.S. Patent
`
`Apr. 27, 2004
`
`Sheet 1 of 6
`
`US 6,726,714 B2
`
`
`
`
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`Page 3
`
`Page 3
`
`

`

`U.S. Patent
`
`Apr. 27, 2004
`
`Sheet 2 of 6
`
`US 6,726,714 B2
`
`34
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`Page 4
`
`

`

`U.S. Patent
`
`Apr. 27, 2004
`
`Sheet 3 of 6
`
`US 6,726,714 B2
`
`
`
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`Page 5
`
`

`

`U.S. Patent
`
`Apr. 27, 2004
`
`Sheet 4 of 6
`
`US 6,726,714 B2
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`

`

`U.S. Patent
`
`Apr. 27, 2004
`
`Sheet 5 of 6
`
`US 6,726,714 B2
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`

`

`U.S. Patent
`
`Apr. 27, 2004
`
`Sheet 6 of 6
`
`US 6,726,714 B2
`
`
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`
`Page 8
`
`

`

`1
`STENT DELIVERY SYSTEM
`
`US 6,726,714 B2
`
`FIELD OF THE INVENTION
`This invention relates to catheters used for delivering
`medical devices. The catheter incorporates sleeves which
`aid in containing the medical device on the catheter, wherein
`the sleeves have portions comprising high modulus material
`to aid in the function of the sleeves.
`
`BACKGROUND OF THE INVENTION
`In typical PTCA procedures, a guiding catheter is percu
`taneously introduced into the cardiovascular System of a
`patient through a vessel and advanced through therein until
`the distal end thereof is at a desired location in the vascu
`lature. Aguidewire and a dilatation catheter having a balloon
`on the distal end thereof are introduced through the guiding
`catheter with the guidewire sliding through the dilatation
`catheter. The guidewire is first advanced out of the guiding
`catheter into the patient's coronary vasculature and the
`dilatation catheter is advanced over the previously advanced
`guidewire until the dilatation balloon is properly positioned
`acroSS the lesion. Once in position acroSS the lesion, the
`flexible, expandable, preformed balloon is inflated to a
`predetermined size with a liquid or gas at relatively high
`preSSures, Such as greater than about four atmospheres, to
`radially compress the arthrosclerotic plaque of the lesion
`against the inside of the artery wall and thereby dilate the
`lumen of the artery. The balloon is then deflated to a small
`profile so that the dilatation catheter may be withdrawn from
`the patients vasculature and blood flow resumed through the
`dilated artery.
`In angioplasty procedures of the kind described above,
`there may be injury to or restenosis of the artery, which
`either necessitates another angioplasty procedure, a Surgical
`by-pass operation, or Some method of repairing or Strength
`ening the area. To Strengthen the area and help prevent
`restenosis, a physician can implant an intravascular proS
`thesis for maintaining vascular patency, commonly called a
`Stent, inside the artery at the lesion. The Stent is expanded to
`a larger diameter for placement in the vasculature, often by
`the balloon portion of the catheter.
`Stents delivered to a restricted coronary artery, expanded
`to a larger diameter by a balloon catheter, and left in place
`in the artery at the site of a dilated lesion are shown in U.S.
`Pat. No. 4,740,207 to Kreamer, PCT Application No. 960
`3092 A1, published Feb. 8, 1996, and U.S. Pat. No. 5,007,
`926 to Derbyshire, the content of which is incorporated
`herein by reference. Palmaz et al., 156 Radiology 73 (1985)
`and U.S. Pat. No. 4,733,665 describe introduction of a stent
`over a balloon catheter.
`The present invention is particularly directed to improved
`arrangements and configurations of sleeves for releasably
`covering the ends of the Stent to prevent the Stent ends from
`flaring and Snagging to better facilitate delivery thereof.
`Examples of Stent retaining sleeves can be found in Savin
`U.S. Pat. No. 4,950,227, U.S. application Ser. No. 09/407,
`836, filed Sep. 28, 1999 and U.S. application Ser. No.
`09/668,496, filed Sep. 22, 2000
`All US patents and applications all other published docu
`ments mentioned anywhere in this application are incorpo
`rated herein by reference in their entirety.
`Without limiting the Scope of the invention in any way,
`the invention is briefly Summarized in Some of its aspects
`below.
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`SUMMARY OF THE INVENTION
`This invention concerns apparatus Suitable for delivery of
`Stents to body cavities. In general, Stents are prosthetic
`devices which can be positioned within a body cavity, for
`example, a blood vessel of the body of a living human or in
`Some other difficultly accessible place. The Stent prosthesis
`is formed of a generally tubular body, the diameter of which
`can be decreased or increased. Stents are particularly useful
`for permanently widening a vessel which is either in a
`narrowed State, or internally Supporting a damaged vessel.
`Such stents are typically introduced into the body cavity by
`use of a catheter. The catheter is usually of the balloon
`catheter type in which the balloon is utilized to expand the
`Stent, which is positioned over the balloon, to place it in a
`Selected location in the body cavity. The present invention is
`particularly directed to improved arrangements for releas
`ably covering/securing the Stent, particularly the ends
`thereof, to the catheter to prevent Snagging of the Stent ends
`and to facilitate delivery thereof. Depending on the type of
`Stent used, the Stent is held in place on the catheter and kept
`from flaring upward at its end(s) by means of at least one
`removable end covering means, or Sock, over the Stent, the
`Stent having been fitted to the catheter over the balloon, as
`by crimping. Most Specifically, this invention is directed to
`improved modifications of Stent retaining sleeves.
`In particular, the invention is directed to an improved Stent
`delivery System designed to hold a Stent over the balloon on
`a catheter, via the sleeve arrangements and to protect the
`Stent from deformation, damage or premature release during
`delivery intraluminally, as well as Snagging during trans
`portation. It is also a purpose of the present invention to
`provide for easier and Smoother removal of the sleeve
`retaining means. The Stent is formed to its lowest geometri
`cal diameter when loaded. The sleeves of the present inven
`tion incorporate high modulus compositions in the form of
`bands, which are positioned over the cone portion of the
`balloon on top of or beneath the socks and preferably bonded
`thereto. The sleeves aid in retaining the Stent and holds the
`stent to the balloon (unexpanded) with little or no relative
`movement between the ID of the stent and the OD of the
`balloon/catheter arrangement. The bands are each preferably
`attached (adhered or welded) to the elastomeric Socks or
`sleeves. One end of the sleeves cover the ends of the stent
`and the other end of the sleeves are respectively attached to
`the catheter. When the balloon under the stent is inflated, the
`bands, which are positioned on the tapered cone portion of
`the balloon, are driven primarily axially, resulting in the
`sleeves being pushed/pulled down the balloon cones to
`allow the stent to deploy. The positioning of the bands on the
`cones of the balloon allows for more of an axial force and
`movement of the Socks when the balloon inflates rather then
`a radial force and provides a flatter profile as apposed to
`other arrangements. This allows for a steadier, Smoother,
`more controlled removal of the Sleeves instead of an abrupt
`release, which may happen with a primarily radial force.
`Since most stents which are deformed to a low diameter will
`increase in diameter Somewhat after being deformed (spring
`back), the sleeves also somewhat prevent Spring back and
`increase the friction fit between the stent and balloon.
`The present invention contemplates a Stent delivery Sys
`tem having Stent retaining sleeves having a high modulus
`ring or band, preferably a polymeric or metal band, located
`along the body of the sleeve. The high modulus band gives
`the sleeve improved retraction properties while allowing the
`Stent edges to deploy. The present invention allows the Stent
`ends to deploy at lower pressures, while assuring full
`retractions of the sleeves.
`Modifications to this embodiment are further described
`below.
`
`Page 9
`
`

`

`US 6,726,714 B2
`
`3
`BRIEF DESCRIPTION OF THE FIGURES
`FIG. 1 is a croSS-Sectional view, in longitudinal Section, of
`the distal end portion of a balloon catheter having a stent
`fixed to the catheter by being crimped thereto over the
`balloon, the ends of the stent being covered by a first
`embodiment of the invention;
`FIG. 2 is similar to FIG. 1 in which the balloon is
`expanded and the Stent has been released;
`FIGS. 3a–C are side views of various ring configurations.
`FIG. 4 is a view of a modification of the embodiment
`shown in FIG. 1;
`FIG. 5 is a view of a modification of the embodiment
`shown in FIG. 1;
`FIG. 6 is a view of a modification of the embodiment
`shown in FIG. 1;
`FIG. 7 is a croSS-Sectional view, in longitudinal Section, of
`the distal end portion of a balloon catheter having a stent
`fixed to the catheter by being crimped thereto over the
`balloon, the ends of the stent being covered by a further
`embodiment of the invention;
`FIG. 8 is similar to FIG. 7 in which the balloon is
`expanded and the Stent has been released;
`FIG. 9 is a view of a modification of the embodiment
`shown in FIG. 7;
`FIG. 10 is a view of a modification of the embodiment
`shown in FIG. 7;
`FIG. 11 is a view of a modification of the embodiment
`shown in FIG. 7;
`FIG. 12 is a view of a modification of the embodiment
`shown in FIG. 7;
`FIG. 13 is similar to FIG. 11 in which the balloon is
`expanded and the Stent has been released; and
`FIG. 14 is an alternative embodiment of the apparatus
`shown in FIG. 13.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`While this invention may be embodied in many different
`forms, there are shown in the drawings and described in
`detail herein specific embodiments of the invention. The
`present disclosure is an exemplification of the principles of
`the invention and is not intended to limit the invention to the
`particular embodiments illustrated.
`For the purposes of this disclosure, the term Stent refers to
`Stents, Stent-grafts, grafts and other endoluminal prostheses
`whether Self-expanding, balloon expandable, Self-expanding
`and balloon expandable or otherwise expandable as are
`known in the art.
`In addition to the over-the-wire embodiments (example
`also found in U.S. Pat. No. 5,980,533) shown in FIGS. 1-4,
`the inventive catheter System may also be provided in a
`rapid-exchange configuration. Examples of rapid-exchange
`catheters may be found in U.S. Pat. Nos. 5,534,007 and
`5,833,706. The inventive stent delivery systems may also be
`made in fixed wire form. Examples of fixed-wire catheters
`may be found in U.S. Pat. No. 5,702,364.
`The System may be adapted for use with a medical device
`Such as a Stent, for example, a Self-expanding, balloon
`expandable or combination Self-expanding and balloon
`expandable Stent. The System may also be used for delivery
`of other medical devices for use in the body as well
`including, but not limited to, ultrasonic devices, laser
`devices, Vena cava filters, implantable drug delivery devices
`and the like.
`
`4
`The inventive medical Systems disclosed herein may also
`be provided with any of the features disclosed in U.S. Pat.
`No. 6,096,056, U.S. Pat. No. 6,068,634, U.S. Pat. No.
`6,036,697, U.S. Pat. No. 6,007,543, U.S. Pat. No. 5,968,069,
`U.S. Pat. No. 5,957,930, U.S. Pat. No. 5,944,726, U.S. Pat.
`No. 5,653,691 and U.S. Pat. No. 5,534,007.
`The Stent delivery System may also comprise various
`coatings as are known in the art, including lubricious coat
`ings to facilitate movement of the various parts of the
`System, as well as collagen-type coatings. More information
`concerning Suitable coatings may be found in U.S. Pat. No.
`5,443,907, and U.S. application Ser. Nos. 08/382,478,
`09/306,939 and 09/316,502.
`Referring to FIGS. 1 and 2, a stent delivery system 10
`includes a catheter Such as an over-the-wire or rapid
`eXchange. Balloon catheters are preferred herein as best
`examples of catheters having an expandable distal end
`portion constructed and arranged for expanding the outer
`diameter of the catheter from a contracted State to an
`expanded state. FIGS. 1 and 2 shows a catheter 10 having a
`outer shaft 16, a guide wire lumen 18 with marker band
`secured thereto 15 and a distal tip 17. A balloon 14 is fixed
`to the distal end of the catheter by adhesive or welding
`attachment of the proximal end 13 to the outer shaft 16 of the
`catheter and the distal end 19 to the inner shaft 18 of the
`catheter. Other arrangements known in the art may be used.
`Balloon 14 is shown in FIG. 1 in its contracted State and in
`FIG. 2 in its expanded state. A stent 20 is held about balloon
`14 by two overlying retaining sleeves, or Socks, 22 and 24,
`which cover the ends 30, 32 of the stent, respectively.
`Various types of Stents may be used with balloon expan
`Sion. For example, the Stent may be a Self-expanding Stent
`which upon release Self-expands and is further expanded or
`is merely aided in release by balloon expansion from the
`sleeves. Such Stents may self-expand elastically or may be
`thermally induced such as stents formed of nitinol or other
`shape memory metals or materials.
`Any kind of stent may be delivered by the system of the
`invention, including plastically deformable or elastically
`deformable, and they may be of any configuration or Struc
`ture So long as they can be loaded at a low diameter and
`deployed at a larger diameter, i.e., have a contracted condi
`tion and being expandable to an expanded condition of large
`diameter.
`Stent 20 may be any of the various types known in the art,
`either balloon expandable or Self-expandable. Exemplary
`stents are shown in U.S. Pat. No. 4,735,665; U.S. Pat. No.
`4,950,227; EPO application 707837 A1, and U.S. Pat. No.
`5,445,646. All of these patents are incorporated herein by
`reference and are intended to be exemplary only and not
`limiting. Various materials including Stainless Steel,
`tantalum, shape memory alloys and plastic may be used.
`Stent 20 is radially compressed, as by crimping to a
`contracted condition, against balloon 14 to a relatively Small
`loaded diameter having an OD of 0.044 inches for example,
`although it has a larger released diameter in the expanded
`condition. Various sized Stents may be used
`Sleeves 22 and 24 may be formed of any material suitable
`for catheter sleeves. By way of example, sleeves may be
`made of an expandable material, including a broad class of
`elastomers, Such as urethanes, Styrenics, Silicones, natural
`rubbers, nylons, Segmented polyamide-polyether-polyesters
`sold under the Pebax(R) (Pebax), polyesters (Arnitel), latex,
`polyether amide, polyolefin copolymer (POC) or Surlyn"M,
`by way of example only. The material should be formable
`into a thin walled tube. Only one sleeve may be provided at
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`one end of the Stent, Such as the distal end. However, the use
`of a pair of Sleeves, one at each end of the Stent, is typical.
`For example, polyurethane tubing or the like can be used,
`having a Shore D scale hardness of preferably 70A-55D and
`having, for example, an ID of 0.032-0.038 inches and a wall
`thickness of 0.002-0.004 inches. Of course, the ID and wall
`thickneSS may be dictated by the size of Stent being used.
`Sleeves 22 and 24 are axially connected along catheter 10 to
`the proximal end of balloon 14 at 26 and to the distal end of
`balloon 14 at 27 by means of adhesive 26, 27 or welding.
`Other methods of connecting the Sleeves to the catheter Such
`as welding or by utilizing a frictional gripping force which
`is produced due to the elasticity of the Sleeve, all methods
`are well known in the art.
`Sleeves 22 and 24 overlap stent 20 at each of its ends 30
`and 32, respectively. Rings or bands 34 are affixed around
`the Sleeves 22, 24 via adhesion, Such as an adhesive, or
`welding. The bands 34 may be embedded into the sleeve.
`The bands are made of a higher modulus material relative to
`the sleeve material. The band material may have higher
`Strength and less elongation than the material of the sleeve.
`The bands also may be any material which forms a closed
`curve or any polygonal Structure, or a combination of the
`two. In an alternative embodiment, the bands may also be
`discontinuous and forming generally circular or polygonal
`shapes. Preferably, the bands are made of a material which
`effectively retains a Substantially annular shape. One func
`tion of the rings is to more effectively and smoothly draw the
`sleeve off of the ends of the Stent, by creating more axial
`movement of the ring 34.
`Bands 34 are positioned over the cone portion of the
`balloon 14, in this example mid-way up the cone, when the
`balloon is in its collapsed configuration. By way of example,
`bands 34 may have Shore D scale hardness of greater than
`55, such as with PEBAX, PET, nylon, plastic, such as
`polyimide or polyethylene, or metal, Such as platinum, gold,
`Stainless Steel or nitinol.
`Referring to FIG. 2, in its expanded state balloon 14 has
`an enlarged diameter with tapered cone portions 36 and 38
`at each end thereof. Stent 20 is released from sleeves 22 and
`24 upon expansion of balloon 14 due to the axial/radial force
`created by balloon causing the sleeves to recede. The Sleeves
`may recede away from the Stent in any manner.
`In at least one manner, the bands draw the Sleeves
`gradually outward, bunching the sleeves between the bands
`34 and the fixed position of the sleeves on the catheter. The
`combination of radial and axial forces are applied to the ring
`34. Since the rings resist the radial force, they are driven
`primarily axially, dragging the sleeves off of the ends of the
`Stent and balloon, while maintaining the sleeves close to the
`balloon. The increased axial pressure allows for a more
`controlled and Steady release of the Stent and balloon, as
`opposed to a Sudden release which may happen when the
`primary force on the sleeve is in the radial direction. AS Seen
`in FIG. 2 the stent deploys. The sleeves contract about
`balloon 14 when it is deflated. Deflation allows balloon 14
`and sleeves 22 and 24 along with catheter 10 to be axially
`removed from the body.
`In assembling polyurethane sleeves, they can be tempo
`rarily Swelled by exposure to a Solvent Such as toluene,
`alcohol, or others as known in the art, or lubricated then
`pushed on the ends of the stent. The sleeves are then bonded
`to the balloon ends with an adhesive or the like. The sleeves
`may also be lubricated to prevent resistance when in use.
`Other embodiments are within the claims to this inven
`tion. For example, referring to FIGS. 3A-C, the bands in the
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`Figures may take the form of a shaped ring (FIG. 3A),
`shaped to surround the cone of the balloon, rings (FIG.3B),
`or wire coils (FIG. 3C). The spiral of the coil may be cut
`only partially into the body as a spiral cut or it may be cut
`all the way through as shown. The cross-section of the bands
`can take any form, Such as Squares or any regular polygon
`as well.
`FIGS. 4-6 show different positions and configurations for
`the bands. Only the distal end of the catheter is shown for
`illustrative purposes. It should be understood that two
`sleeves, one on either end of the balloon, may be utilized.
`In FIG. 4, the sleeve 24 has two bands 34, one being
`partially embedded on the inside of the sleeve and one
`partially embedded on the outside of the sleeve 24.
`Preferably, the bands are in mirroring positions relative to
`the sleeve 24 over the cone portion.
`In FIG. 5, the bands 34 are substantially embedded within
`the sleeve 24. This allows the profile of the catheter to be
`reduced.
`In FIG. 6, the sleeves comprise two portions 36, 38
`separated by the bands 34. In this embodiment, portions 36,
`38 of the sleeve 24 are attached on either side of the band 34
`via adhesion or welding or via an integral connection. It
`should be understood that the bands need not be spherical as
`shown. Various cross-sectional shapes may be incorporated
`FIGS. 7-12 illustrate further embodiments of the inven
`tion. These figures show two-piece sleeves, wherein one
`piece comprises material as described above in reference to
`band 34, that being high modulus material, and one piece
`comprises material as described above in reference to
`sleeves 22 and 24, that being lower modulus material.
`Hereafter, the two pieces which make up the sleeves will be
`referred to as high modulus (HM) bands and low modulus
`(LM) bands. The use of the words “low” and “high” are
`meant to indicate the level of modulus for the two pieces of
`the sleeves, each relative to the other. For example, the HM
`bands have a higher modulus relative to the LM bands.
`In FIGS. 7-8, as in FIGS. 1-2, a balloon catheter is shown
`in its collapsed form and in its expanded form, respectively.
`The Stent retaining Sleeves 40, 42 comprise two pieces.
`Sleeves 40, 42 comprise a HM band 48 and a LM band 50.
`In this embodiment, one end of the HM bands 48 is
`connected to the balloon at 46 and 47 in the same manner as
`described above, while the remaining ends of the HM bands
`are in abutting connection 52 with the LM bands 50. The
`remaining ends of the LM bands 50 cover the corresponding
`end margins of the stent 20.
`FIGS. 9-12 show different positions and configurations
`for the sleeves. Only the distal end of the catheter is shown
`for illustrative purposes. It should be understood that two
`sleeves, one on either end of the balloon, may be utilized.
`In FIG. 9, sleeve 54 comprises two pieces. The LM band
`56 extends from being attached via conventional means to
`the balloon at point 58 to a point over the margin of the stent
`20. The HM band 60 is attached to the LM band 56 over
`point 58 extending partially up the cone portion of the
`balloon.
`In FIG. 10, sleeve 62 comprises two pieces. The HM band
`64 extends from being attached via conventional means to
`the balloon at point 66 to a point partially up the cone portion
`of the balloon 14. The LM band 68 is attached to the HM
`band 64 over point 66 extending along the balloon 14 over
`the margin of the stent 20.
`In FIG. 11, sleeve 70 also comprises two pieces. The HM
`band 72 extends from being attached via conventional
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`means to balloon at point 73 to a point partially up the cone
`portion of the balloon 14. The HM band 72 is in overlapping
`connection with the LM band 74 at point 75. The LM band
`74 extends from point 75 to over the margin of the stent 20.
`In this embodiment, the HM band 72 overlaps the LM band
`74.
`In FIG. 12, sleeve 76 also comprises two pieces. The HM
`band 78 extends from being attached via conventional
`means to balloon at point 79 to a point partially up the cone
`portion of the balloon 14. The HM band 78 is in overlapping
`connection with the LM band 80 at point 81. The LM band
`74 extends from point 81 to over the margin of the stent 20.
`In this embodiment, the LM band 80 overlaps the HM band
`78.
`It should be understood that the present application con
`15
`templates embodiments as described above where the LM
`bands and the HM bands are exchanged.
`It should also be understood that the sleeves may be
`attached to the catheter or the waist portions of the balloon,
`for example at point 73, via adhesion or in direct contact via
`welding.
`FIGS. 13-14 show examples of the retraction of the
`sleeves when the balloon is expanded. The size of the
`balloons appear to be constant, however, it should be under
`stood that the illustration is directed to the action of the
`sleeves during expansion and deployment of the Stent.
`In FIG. 13 the sleeve 84 comprises a LM band 86 and a
`HM band 88. During expansion of the balloon 14, the sleeve
`84 recedes, or folds back onto itself. In this embodiment, the
`LM band 86 comprises a majority of the recession, while the
`HM band 88 retains more of its original shape. This is due
`in part to the