Note: Descriptions are shown in the official language in which they were submitted.
~32~553
TITLE OF THE INVENTION
Guide Wire
BACKGROUND OF THE INVENTION
This invention relates to a guide wire which is used
to introduce a catheter to the predetermined site of a human
body for treatment and examination purposes.
One of advanced medical practices in these years is to
introduce a catheter into a blood vessel for the purposes of
examination and treatment of heart diseases. In lntroducing
the catheter to the predetermined site of a human body, a
guide wire is inserted into the catheter until the leading
edge of the guide wire slightly projects beyond the leading
edge of the catheter so that the guide wire may lead the
catheter to the predetermined site.
Several types of catheter guide wires are known in the
art includin~ those disclosed in EPA 0141006. These guide
wires generally include a core having at least a distal
portion thereof formed of a super-elastic alloy and a coating
of synthetic resin enclosing the entire core. The guide
wlres can efflciently guide the catheter because of the high
flexibility and elastic recovery of the distal portion.
Although the above-mentioned guide wires are excellent
2~5 in guidance of the catheter, they are less sensitive to
radiographic X-rays. In general, the core is merely coated
with synthetic resin. It may be devised to add a radiopaque
material to the synthetic resin coating. However, the amount
of such radiopaque matexial added is limited because the
;~ 3Q radiopaque material can adversely affect the physical
properties of the resin coating. Consequently, the guidie
wire as a whole cannot have fully high radiographic
sensitivity. In particular, since the distal portion of the
metallic core is made slender, the X-ray radiographic
35 ~ sensitivity of the distal portion is undesirably low.
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i 132~553
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Nowadays, it is attempted to introduce a catheter into a
thinner blood vessel, for example, intracerebral vessels and
kidney vessels. To this end, the catheter must be of smaller
diameter and the guide wire must be accordingly thinn0r.
Then the guide wire of the type wherein the core is coated
with synthetic resin cannot provide suficient radiographic
sensitivity particularly at its distal portion. This will
make more difficult the operation of introducing the catheter
to the predetermined site.
i SUMIIARY OF THE INVENTION
Therefore, an object of the present invention is to
provide a novel and improved catheter guide wire of the
design that maintains sufficient radiographic sensitivity
particularly at its distal portion even when it has a small
diameter, facilitating the introduction of the associated
catheter to the predetermined site in a blood vessel.
According to the present invention, there is provided
a guide wire comprising
an elongated core formed o~ a super-elastic alloy
including a body portion having high rigidity and a distal
portion integrally formed`with the body portion, but having a
-smaller diameter and a lower rigidity than said body portion,
said distal portion providing a leading edge of the core;
an annular member made of a radiopaque metal secured to
the leading edge of said core; and
an envelope of synthetic resin enclosing the entirety
of said core including the annular member and having a
substantially even outer diamet~r.
It is to be noted that the terms radiography and
radiographic sensitivity used in the present dlsclosure refer
to X-ray radiography and X-ray radiographic sensitivity.
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BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features, and advantages
of the present invention will be better understood from the
following description taken in conjunction with the
accompanying drawings, in which:
FIG. 1 is a longitudinal cross section of a guide wire
according to one preferred embodiment of the present
invention;
FIG. 2 is an enlarged transverse cross section of the
guide wire taken along lines II-II in FIG. 1; and
FIG. 3 is a longitudinal cross section of a guide wire
according to another preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, there is illustrated in
longitudinal cross section a guide wire according to one
preferred embodiment of the present invention. FIG. 2 is an
enlarged transverse cross section of the guide wire taken
along lines II-II in FIG. 1.
Briefly stated, the guide wire generally designated at
1 according to the present invention comprises an elongated
core 2 including a body portion 2a having high rigidity and a
distal portion 2b integrally formed with the body portion 2a
but having a smaller diameter and lower rigidity than the
body portion. The distal portion 2b provides a leading edge
of the core. Means for providing radiographic sensitivity 3
is provided at the leading edge of the core 2. An envelope 4
of synthetic resin encloses the entirety of the core 2
including the radiographically sensitive means 3 and has a
substantially even outer diameter.
The guide wire of the present invention is described
in more detail by referring to FIGS. 1 and 2.
The guide wire 1 has the core 2 including body and
distal portions 2a and 2b which are most often formed as a
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one-piece member from a super-elastic alloy. It is to be
noted that the right side as viewed in FIG. 1 is a leading
edg~ of the guide wire or core. The body portion 2a i5
usually an elongated tubular member having a suitably chosen
diameter. The distal portion 2b is also a tubular member,
but is tapered. The diameter of the distal portion 2b is
gradually reduced from the connection to the body portion to
the tip thereo~. No definite boundary need be present
between the body and distal portions, and the distal portion
is distinguishable from the body portion in that the distal
portion is tapered~ Because of its smallex diameter, the
distal portion 2b is less rigid than the body portion. A
core having such a tapered distal portion is improved in
operability because the distal portion can be bent more or
less when a certain force is applied to the leading edge.
The core 2 is preferably formed of super-elastic
alloys, for example, Ti-Ni alloys having 49 58 atom~ of
nickel, Cu-Zn alloys having 38.5-41.5~ by weight of Zn, Cu-
Zn X alloys having 1-10% by welght of X wherein X is selected
from th~ group consisting of Be, Si, Sn, Al and Ga, and Ni-Al
alloys having 36-38 atom% of aluminum. The most preferred
alloys are Ti-Ni alloys of the above composition~ The body
portion 2a of the core 2 preferably has an outer diameter of
about 0.10 to about 1.00 mm, more preferably about 0.15 to
about 0.40 mm, a length of about 1,000 to about 4,000 mm,
more preferably about 1,500 to about 3,000 mm, a buckllng
strength (yield stress under load) of about 30 to about 100
kg/mm2 at 22C, more preferably about 40 to about 55 kg/mm2
at 22C, and a restoring stress (yield stress upon unloadlng)
of 20 to about 80 kg/mm2 at 22C, more preferably about 30 to
about 35 kglmm2 at 22C. ~he distal portion 2b of the core 2
preferably has an outer diameter of about 0.03 to about 0.15
mm, more preferably about 0.05 to about 0.10 mm, a length of
about 10 to about 300 mm, more preferably about 50 to about
150 mm, a bending load of about 0.1 to about 10 grams, more
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" 1324~53
preferably about 0.3 to about 2.0 grams, and a restoring load
of about 0O1 to about 10 grams, preferably about 0.3 to about
2.0 grams.
In the preferred embodiment in which the distal
portion 2b has a continuously reducing diameter toward its
leading edge, the outer diameter of the distal portion is con-
structed as an average of its reducing diameter per its
length. The body and distal portions each need not have an
equal value of restoring stress over their length, but are
rather desired to have restoring stress varied by a heat
treatment so that controlled physical properties are
available at different diameters. More particularly, the
body and distal portions are separately heat treated such
that the body portion may have a greater value o`f restoring
stress and the distal portion may be more flexible. The core
2 is not limited to a single member and may comprise a
plurality of parallel extending or twisted strands insofar as
the above-mentioned design and function, that is, a tapered
portion connected to a rod-shaped portion and stepwise or
continuously varying physical properties are available.
The radiographically sensitlve means is illustrated
in FIGS. 1 and 2 as an annular member 3 secured to the
leading edge of the core 2. The annular member 3 is a
tubular member in the illustrated embodiment. The annular
member 3 is preferably formed of a radiopaque metal, for
example, gold, platinum, lead, silver, bismuth, and tungsten,
most preferably gold. The radiographically sensitive annular
member 3 may be secured to the leading edge of the core 2 by
any desired methods including mechanical methods like press
fitting and bonding methods like brazing or soldering with or
without a matchlng metal plated or vapor deposited on the
leading edge of the core 2. The matching metal, when plated
or vapor deposited on the leading edge of the core 2, is
preferably Ni or of the same metal as the particular
radiopaque metal used when the core 2 is of a Ti-Ni alloy.
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1~24~3
The matching metal is preferably Zn or of the same metal as
the particular radiopaque metal used when the core 2 is of a
Cu-Zn or Cu-Zn~X alloy. The matching metal is preferably Ni
or of the same metal as the particular radiopaque metal used
when the core 2 is of an Ni-Al alloy. The solders used
herein are preferably hard solder~ including silver and gold
solders.
The radiographically sensitive annular member 3
preferably has an outer diameter of about 0~2Q to about 0.90
mm, more preferably about 0.25 to about 0.40 mm, an inner
diameter of about 0.04 to about 0.16 mm, more preferably
about 0.06 to about 0.11 mm, and a length of about 1.0 to
about 10.0 mm, more preferably about 1.5 to about 4O0 mm.
Another example of the radiographically sensitive
annular member 3 is illustrated in FIG. 3. In the embodiment
of FIG. 3, the radiographically sensitive annular member 3 is
a coil formed by winding a slender filament of a radiopaque
metal as defined above around the leading edge of the core 2.
Preferably, a filament having a diameter of about 0.02 to
about 0.10 mm i8 wound over an axial distance of about 1.0 to
about 10.0 mm, more preferably about 1.5 to about 4.0 mm from
the leading edge of the core.
The radiographically sensitive annular member 3 in the
form of a coil may be provided by any desirad methods as by
directly winding a filament around the core or attaching a
pre-wound coil onto the leading portion of the core. The
coil is preferably secured to the leading portion of the
cor`e, for example, by externally fastening the coil under
pres3ure. Alternatively, the radiographically sensitive coil
may be secuxed to the leading portion of the core by plating
or vapor depositing to the leading portion a matching metal
capable of promoting the bond to the coil, winding a filament
thereon in coll form or attaching a pre-wound coil therato,
and brazing the coil to the matching layer.
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In addition to the tubular member and coil mentioned
above, the radiographically sensitive means 3 may be formed
by applying and press bonding a foil of radiopaque metal to
the core leading portion, or plating or evaporating a
radiopaque metal to the core leading portion to form a
radiographically sensitive layer. In this case, the metal
foil and deposited layer preferably have a thickness of at
least 50 microns.
The synthetic resin envelope 4 covers the entirety of
the core 2 including the radiographically sensitive means 3.
The envelope 4 has a substantially even outer diameter from
the trailing edge to the leading edge as shown in FIGS. 1 and
3. The outer diameter of the envelope 4 is made
substantially equal over its entire length in order that any
irregularities on the core 2 including a step formed by the
radiographically sensitive means 3 at the leading edge of the
core 2 do not appear as the outer contour of the guide wire
1. The envelope 4 may be formed of any desired synthetic
resins including polyethylene, polyvinyl chloride, polyester,
polypropylene, poIyamide, polyurethane, polystyrene, fluoro-
plastics, silicone rubber and othPr various elastomers and
composites. Preferably the envelope 4 is sufficiently
flexible to allow free bending of the core 2 and provides a
smooth continuous outer surface free of ixregularities.
The envelope 4 may be further coated with an anti-
coagulant, for example, heparin and urokinase, and an anti-
thrombotic agent, for example, silicone rubber, urethane-
~ilicone block copolymers such as cardiothane (for example,
Abcothane, trade mark, available from Kontron Inc.), and
hydroxyethyl methacrylate-styrene copolymers~ It is also
recommended to form the envelope 4 from a fluoroplastic resin
or another resin capable of providing a low friction surface.
A lubricating fluid such as silicone fluid may be applied to
the outer surface of the envelope 4 to reduce the friction of
the guide wire. It is preferred to incorporate a radiopaque
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material into the resin to form the envelope 4 because it
becomes more easy to locate the guide wire during its
introduction lnto the vessel. The radiographically sensitive
material may be a metal such as Ba, W, Bi, Pb or a compound
thereof in fine powder form.
The envelope 4 has a substantially even outer diameter
as described above. The term substantially even i~ used to
encompass not only a completely even outer diameter, but also
an envelope having a slightly tapered leading portion. The
use of the envelope 4 having a substantially even outer
diameter up to the leading edge minimizes the possible damage
of the vascular inner wall by the gulde wire. The outer
diameter of the envelope 4 is preferably in the range of from
about 0.25 to about 1.04 mm, more preferably from about 0.30
to about 0.64 mm. Accordingly, the envelope 4 has a wall
thicknass o~ about 0.03 to about 0.25 mm, preferably about
0.05 to 0.15 mm on the core body portion ~a.
The envelope 4 preferably enclose~ the core 2 in close
contact relationship and is secured to the core both at the
distal and body portions thereof. Such requirement can be
met simply by applying a resin compound to the core, for
example, by melt extrusion. It is also possible to form a
hollow tube of synthetic resin compound, inserting the core
into the tube, and securing the tube to the core at suitable
2S ~ites from the leading edge to the trailing edge by adhesive
bonding or fusion welding.
The leadin~ edge of the guide wire 1 or the envelope 4
is preferably rounded to provide a semi-spherical surface as
shown in FIGS. 1 and 3 in order to prevent any damage of the
vascular wall and to facilitate the operation of the guide
wire.
Preferably, the envelope 4 has a lubricating material
atta¢hed to the surface thereof. By the lubricating material
is meant a material which exhibits lubricating nature when
wetted with water. The lubricating materials are typically
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~3245~3
water-soluble high molecular weight materials and derlvatives
thereof. The lubricating materials are attached to the
surface of the synthetic resin envelope through covalent or
ionic bond~. These lubricating materials are generally
chain-structured, non-crosslinked high polymers having a
hydrophilic group such as -OH, -CONH2, -COOH, -NH2, -COO-,
and -SO3-. ~he lubricating materlals absorb water to exhibit
lubricity when wetted with water, that is, contactqd with
blood.
The operability of the guide wire 1 is improved by
attaching such a lubricating material to the envelope 4 or
the outer surface of the guide wire 1 because when the guide
wire is received in the catheter, the friction between the
catheter inner wall and the guide wire outer wall is
minimized to facilitate sliding motion of the guide wire
within the catheter.
Exemplary lubricating materiaIs are natural water-
soluble h~gh polymers, for exa~ple, starches such as
carboxymethyl starch and dialdehyde starch; celluloses such
as carboxymethyl cellulose and hydroxyethyl cellulose;
tannins and lignins; polysaccharides such as alginic acid,
: gum arabic, heparin, chitin, and chitosan; and proteins such
as gelatin and casein. Another class of lubricating material
: include~ ~ynthetic water-soluble high polymers, for example,
polyvinyl alcohol; polyalkylene oxides such as polyethylene
oxide; polyalkylene glycols such as polyethylene glycol;
acrylates such as sodium polyacrylate; maleic anhydride
polymer~ such as methyl vinyl ether-maleic anhydride
: copolymers, methyl vinyl ether-sodium maleic anhydride,
methyl vinyl ether-ammonium maleic anhydride, maleic
anhydride-ethyl ester copolymers; phthalates such as poly-
(hydroxyethyl phthalate); water-soluble polyesters such as
poly(dimethylol propionate); acrylamides such as poly-
: acrylamide hydrolyzates, quaternized polyacrylamide; poly
vinyl pyrrolidone; polyethylene imine; polyethylene
~ 1324~53
- 1 0 -
sulfona-te; and water-soluble nylons. Preferred are maleic
anhydride polymers, especially maleic anhydride-ethyl ester
copolymers.
The derivatives of these water-soluble high polyme~s
are not limited to water-soluble ones, but may be of any form
so long as they have the above-mentioned water-soluble high
polymer as a basic structure. Even insolubilized derivatives
may be employed so long as they absorb water to provide
lubricity when wetted. Examples include esters, salts,
amides, anhydrides, halides, ethers, hydrolyzates, acetals,
formals, alkylols, quaternized products, diazos, hydrazides,
sulfonates, nitrates, and ion complexes which are obtained by
addition, substitution, oxidation, or reduction reaction of
the above-mentioned water-soluble high polymers. Also
included are polymers crosslinked with substances having more
than one reactive functional group such as diazonium group,
azide group, isocyanate group, acid chloride group, acid
anhydride group, imino carbonate group, amino group, carboxyl
group, epoxy group, hydroxyl group, and aldehyde group. Also
20 included are copolymers with vinyl compounds, acrylic acid,
methacrylic acid, diene compounds, and maleic anhydride.
In this case, the synthetic resin of the envelope
should preferably possess a reactive functional group capable
of ionic or covalent bond with the lubricating material, or
contain a compound possessing such a reactive functional
group, or have such a reactive functional group introduced
therein as will be described later.
The lubricating material is bonded with a reactive
functlonal group existing or introduced in the synthetic
resin to impart lubricity to the surface of the synthetic
resin. The lubricating layer thus formed on the surface is
long lasting without being dissolved in water. Reference is
fir~t made to the lubricating layer attached to the
underlying synthetic resin throu~h a covalent bond. The type
of lubricating material is not critical, but there can be
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~3245~3
mentioned as typical examples celluloses, maleic anhydride
polymers, acrylamides, polyethylene oxides, and water soluble
nylons as mentioned a~ove. Particularly preferred among them
are hydroxypropyl cellulose, methyl vinyl ether-maleic
anhydride copolymers, polyacrylamide, polyethylene glycol,
and water-soluble nylon (AQ-Nylon P-70 manufactured and sold
by Toray K.K.). The avera~e molecular weight of the
lubricating material is not critical although those having a
molecular weight of about 30,000 to 5,000,000 advantageously
form a lubricating layer of an appropriate thickness having
increased lubricity and a controlled degree of swelling upon
water absorption.
The lubricating materials which are attached to the
underlying synthetic resin through an ionic bond include
polyvinyl pyrrolidonel and carboxylates, sulfonates, and
ammonium salts of the foregoing water-soluble high polymer~.
More illustratively, examples of the carboxylates include the
sodi~m salt o~ methyl vinyl ether-maleic anhydride, sodium
polyacrylate~ polyacrylamide hydrolyzate, sodium carboxy-
methyl cellulose, and sodium alginates; examples of the
sulEonates include sodium poly(styrene sulfonate) and sodium
poly(vinyl sulfonate); and examples of the ammonium salts
include the ammonium salt of methyl vinyl ether-maleic
anhydride and quaternized polyacrylamide.
The reactive functional groups exlsting or introduced
in the synthetic resin are not critical insofar as they are
reactive, bondable and crosslinkable with the lubricating
material to bind it. Examples of the reactive functional
groups include a diazonium group, azide group, isocyanate
group, acid chloride group, acid anhydride group, imino
carbonate group, amino group, carboxyl group, epoxy group,
hydroxyl group, ~nd aldehyde group. Particularly preferred
are isocyanate, amino, aldehyde and epoxy groups.
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Then, polyurathanes, polyamides and the like are
pre~erred as the reactive functional group-bearing synthetic
resin.
Other examples of the reactive functional yroup-
bearing material are isocyanates such as methylenediisocyanate~ ethylene diisocyanate, toluene diisocyanate,
and diphenyl methane diisocyanate, and adducts and
prepolymers of these isocyanates with polyols. Also included
are low molecular weight polyamines such as ethylene diamine,
trimethylene diamine, 1,2-diaminopropane~ and tetramethylene
diamine; and high molecular weight polyamines, for example,
(i) poly(alkylene polyamines) synthesized from amines and
alkylene dihalides or epichlorohydrin, (ii) alkylene imine
polymers produced through open-ring polymerization of
alkylene imines such as ethylene imine and propylene imine,
and (iii) polyamines such as polyvinyl amine and polylysine.
Also included are polyaldehydes such as glutaraldehyde
and terephthalaldehyde, and polyepoxides such as ethylene
glycol diglycidyl ether.
EXAMPLES
Examples of the present invention are given below by
way of illustration and not by way of limitation.
Example 1
A guide wlre as shown in FIG. 1 was prepared. A
length of core was prepared from a Ti Ni alloy having 56
- atom~ of Ni. The core had an entire length of 1,800 mm, a
leadlng edge diam~ter of 0.06 mm, and a trailing edge
diameter of 0.25 mm. The leading or distal portion of the
core extending 120 mm from the leading edge was tapered
toward the leading edge. A rlng of pure gold was prepared
which had an inner diameter of 0.07 mm, an outer diameter of
0.3 mm, and an axiaI length of 2.0 mm. The ring was put onto
~35 the leading portion of the core and secured thereto by
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fastening the ring against the core using a clamping tool,
providing a radiographically sensitive portion.
A polyurethane composition containing 45% by weight of
tungsten fine powder having a particle size of about 3-4 ~m
was then extruslon molded on the core over its entire outer
surface to form a resin envelope having a substantially even
outer diameter. A solution containing 5 r 0% by weight of a
maleic anhydride-ethyl ester copolymer in tetrahydrofuran was
applied to the polyurethane envelope to bind the maleic
anhydride-ethyl ester copolymer to the poly~lrethane, forming
a lubricating surface.
The final guide wire had an overall length of about
1,800 mm, an overall diameter of 0.36 mm and its distal
portion had a bending load o about 4 grams and a restoring
load of about 2 grams.
; An X-ray radiograph of the guide wire as a whole was
taken, finding a definite radiographic image of the distal
portion.
The opera~ion of the guide wire is described.
Example 2
The guide wire 1 shown in FIG. 1 and prepared in
Example 1 was inserted into a catheter (not shown in FIG~ 1)
until the leading edge of the guide wire slightly projected
beyond the leading edge of the catheter. The catheter having
the guide wire received therein was then introduced into a
blood vessel so that the leading edge of the guide wire might
lead that of the catheter. The guide wire along with the
catheter was slowly advanced through the vessel while
externally locating the leading edge of them through a
radiographic observation. After the leading edge of the
catheter had reached the predetermined site along the vessel,
the guide wire was withdrawn from the catheter.
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As described above, the guide wire according to the
present invention comprises an elongated core including a
body portion having high stiffness and a distal portion
integrally formed with the body portion, but having a smaller
diameter and lower stlffness than the body portion, means at
the leading edge o~ the core for providing radiographic
sensitivity, and an envelope of synthetic resin entirely
enclosing the core including the radiographically sensitive
means and having a substantially even outer diameterO
Particularly the radiographically sensitive means disposed at
the leading edge oE the core ensures that the leading edge is
visually located through a radiographic observation,
facilitating insertion of the guide wire into a catheter and
subsequent lntroduction of the catheter into a blood vessel.
When the core is formed of a super-elastic alloy and
the distal portion is tapered toward the leading edge, the
distal portion will bend a relatively large angle under a
certain stress and have recoverable elastic strain. When the
leading edge of the guide wire advances past a bend of the
vessel, the distal portion undergoes substantial ~lexural
deformation under a relatively small load and thus has an
improved response. The distal portion will repeakedly bend
or de~orm and recover as it passes bends or curves of the
; vessel, without causing damage to the vascular wall. The
guide wire has improved sh~pe followability to a sexpentine
blood vessel. The guide wire will relatively readily bend
even at a branch of vessel. Consequently, the guide wire can
be introduced to the predetermined site in the vessel without
substantial difficulty.
In addition, the body portion of the guide wire has
improved torque transfer in either twlsting direction,
ensuring that the leading edge is readily advanced to the
desired direction by applying a properly selected twisting
torque to the body portion. The guide wire can thus be
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introduced to the predetermined site through a winding vessel
with a relatively easy manual operation.
Obviously many modifications and variations of the
present invention are possible in the light of the above
teachings. Although a tapered head is described as the
preferred distal portion in the above embodiments, a tubular
head having an equal diameter or a modified head having
stepwise varying diameters may be used as the distal portion.
In this case, a step is formed at the connection between the
distal and body portions, but an envelope may be evenly
coated over the core to accommodate the step, providing a
smooth outer surfaceO It is therefore to be understood that
within the scope of the appended claims the invention may be
practiced otherwise than as specifically described.
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