United States Patent (19)
`Sutton
`
`54 FILEXIBLE CATHETER
`75) Inventor: Gregg S. Sutton, Plymouth, Minn.
`73) Assignee: Navarre Biomedical, Ltd., Plymouth,
`Minn.
`
`(21) Appl. No.: 701,569
`22 Filed:
`Aug. 22, 1996
`Related U.S. Application. Data
`63) Continuation of Ser. No. 564,984, Nov. 30, 1995, aban
`doned, which is a continuation of Ser. No. 344,821, Nov. 23,
`1994, abandoned.
`int. Cl. ............... A61M 25/00
`(51)
`52 U.S. Cl. ........................ 604/282; 604/264; 604/280
`58) Field of Search .............................. 604/95, 282, 264,
`604/270, 280, 281
`
`56
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`1,667,443 4/1928 Simonsen ................................ 604/264
`2,269,823
`1/1942 Kreiselman.
`3.52,620 7/1970 Cook ......................................... 604/95
`4,456,017 6/1984 Miles.
`4,464,176 8/1984 Wijayarathna.
`4,596,563 6/1986 Pande.
`4,639,252
`1/1987 Kelly et al. ............................. 604/282
`4,655,746 4/1987 Daniels et al. .
`4,739,768
`4/1988 Engelson.
`4,748,979
`6/1988 Hershenson.
`4,798,598
`1/1989 Bonello et al. ....................... 604/95 X
`4,813,434 3/1989 Buchbinder et al. ................. 604/95 X
`4,813,934 3/1989 Engelson et al. .
`4,838,268
`6/1989 Keith et al. .
`4,842,590
`6/1989 Tanabe et al. .
`4,884,579 12/1989 Engelson.
`4,917,666 4/1990 Solar et al. ........................... 604/96 X
`4,955,862 9/1990 Sepetka.
`4,976,690 12/1990 Solar et al..
`4,985,022
`1/1991. Fearnot et al. .......................... 604/282
`4,994,069 2/1991 Ritchart et al. .
`5,045,072
`9/1991 Castillo et al. .
`5,047,045 9/1991 Amey et al..
`5,095,915 3/1992 Engelson.
`
`US005704926A
`11) Patent Number:
`45) Date of Patent:
`
`5,704,926
`Jan. 6, 1998
`
`5,135,494 8/1992 Engelson et al..
`5,147,317 9/1992 Shank et al. ........................ 604/282 X
`5,171,232 12/1992 Castillo et al..
`5,178,158
`1/1993 de Toledo ........................... 604/282 X
`5,195,989 3/1993 Euteneuer.
`5228,453 7/1993 Sepetka.
`5.243,988 9/1993 Sieben et al. .
`5,308,324 5/1994 Hammerslag et al. ................ 604/95
`5,334,169 8/1994 Brown et al........................ 604/280
`5,378,234
`1/1995 Hammerslag et al. .
`....... 604/95
`5,395,332 3/1995 Ressemann et al. ................ 604/28OX
`
`OTHER PUBLICATIONS
`"Care and Maintenance of Cardiac Catheters,” brochure
`entitled U.S.C.I. Cardiac Catheters and Electrodes United
`States Catheter & Instrument Corporation, Glens Fall, New
`York, copyright 1961, three sheets.
`Product sheet entitled "Catheters for Cardiology,” United
`States Catheter & Instrument Corp., Glens Falls, New York,
`1963 two sheets.
`
`(List continued on next page.)
`Primary Examiner-Michael Powell Buiz
`Assistant Examiner-N. Kent Gring
`Attorney, Agent, or Firm-Gregory P. Kaihoi
`57)
`ABSTRACT
`The invention provides a catheter capable of delivering
`drugs or other fluids to a desired remote location in a bodily
`passageway, such as a small, tortuous artery. The catheter of
`the invention includes inner and outer tubular layers, and a
`continuous helical wire coil disposed between the tubular
`layers along substantially the entire length of the catheter. To
`enhance trackability and pushability, the wire coil is con
`structed to provide regions of differing flexibility to the
`catheter. The wire coil in a first portion of the catheter has
`a first coil pitch and the wire coil in a second section of the
`catheter has a second coil pitch which is larger than the first
`coil pitch to provide the second section of the catheter with
`greater flexibility than the first section.
`
`20 Claims, 2 Drawing Sheets
`
`
`
`A.
`
`f7
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`Page 1
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`5,704,926
`Page 2
`
`OTHER PUBLICATIONS
`
`Product brochure entitled "Cardiology Radiology Surgery,
`Cardiovascular Catheters and Accessories,” United States
`Catheter & Instrument Corp., 1967,68, five sheets.
`Product brochure entitled "Cardiovascular Catheters and
`Accessories-Cardiology Radiology Surgery,” United
`States Catheter and Instrument Corporation, Glens Falls,
`New York, 1969, six sheets.
`
`Product brochure entitled "Cardiovascular Catheters and
`Accessories-Woven Dacron, Teflon and Polyethylene
`Materials," USCI, a Division of C.R. Bard, Inc., Billerica,
`Massachusetts, Jun. 1974, eight sheets.
`Product brochure entitled "Venture into the New Frontier,'
`SciMedLife Systems. Inc., Maple Grove, Minnesota, 1993,
`one sheet.
`Brochure entitled "TransitTM Infusion Catheter-Taking the
`Kinks Out of Interventional Therapy." Cordis Endovascular
`Systems, Inc., Miami Lakes, Florida, Oct. 1993, two sheets.
`
`Page 2
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`Medtronic Exhibit 1472
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`U.S. Patent
`
`Jan. 6, 1998
`
`Sheet 1 of 2
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`5,704,926
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`Page 3
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`Medtronic Exhibit 1472
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`U.S. Patent
`
`Jan. 6, 1998
`
`Sheet 2 of 2
`
`5,704,926
`
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`
`en
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`S.
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`Page 4
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`1
`FLEXBLE CATHETER
`
`5,704,926
`
`This application is a continuation of application Ser. No.
`08/564,984, filed Nov.30, 1995 now abandoned, which is a
`continuation of application Ser. No. 08/344,821, filed Nov.
`23, 1994 now abandoned.
`
`FIELD OF THE INVENTION
`This invention relates to catheters used in medical pro
`cedures.
`
`O
`
`15
`
`2
`constructing a catheter from two lengths of tubing of dis
`similar materials, one being more flexible than the other
`(see, e.g., U.S. Pat. No. 4.842.590). Such constructions
`introduce additional manufacturing complexity, however, in
`joining such lengths in a consistently reliable fashion. Oth
`ers have utilized dissimilar metal reinforcing materials to
`achieve differing flexibility - - - e.g., relatively stiffer wire
`braiding in the proximal portion and a relatively more
`flexible helical coil in the distal portion. Again, the use of
`such differing materials requires careful quality control in
`manufacturing to assure proper performance at the junction
`of the dissimilar materials.
`There is, therefore, a need for catheters that provide a
`variable degree of flexibility in a relatively small size (i.e.,
`diameter) to facilitate access to remote locations through
`sometimes lengthy and tortuous passageways. As the push
`ability of catheters generally decreases with smaller size and
`greater flexibility, there is a need for such flexible, small
`catheters that have excellent pushability and trackability and
`are without introducing manufacturing complexities.
`SUMMARY OF THE INVENTION
`The invention provides a catheter capable of delivering
`drugs or other fluids to a desired remote location in a bodily
`passageway, such as a small, tortuous artery. The catheter of
`the invention includes inner and outer tubular layers, and a
`continuous helical wire coil disposed between the tubular
`layers along substantially the entire useable length of the
`catheter. To enhance both trackability and pushability, the
`wire coil is constructed to provide regions of differing
`flexibility to the catheter. The wire coil in a first (typically
`proximal) portion of the catheter has a first coil pitch (i.e.,
`the distance, measured center to center along the length of
`the catheter, from one turn of the wire coil to the next
`adjacent turn), and the wire coil in a second (typically distal)
`section of the catheter has a second coil pitch which is larger
`than the first coil pitch to provide the second section of the
`catheter with greater flexibility than the first section. The
`first, less flexible section therefore typically has greater
`pushability, and typically comprises a substantial portion of
`the length of the catheter, with the second, more flexible (and
`therefore typically less pushable) portion comprising a distal
`section of at least, e.g., about 5 cm, and preferably about
`15-30 cm. Desirably the pitch of the wire coil in the second
`portion is at least about 25% larger than in the first portion,
`and preferably at least about 50% larger.
`The wire coil preferably terminates very close to the distal
`end of the catheter, desirably within a distance of not more
`than about five times the outer diameter of the tubular layers
`(and preferably not more than the actual diameter of such
`layers), measured at the distal end of the wire coil. In a
`preferred embodiment one or both ends of the wire coil are
`secured by a weld attaching at least two (preferably three)
`adjacent turns of the coil to one another. A radiopaque
`marker may be provided, disposed between the tubular
`layers at the distal end of the catheter (either positioned just
`distally of the distal end of wire coil, or positioned over this
`distal end portion of the wire coil). Preferably the wire coil
`is made from a metal wire having a generally rectangular
`cross-section. In a preferred embodiment, the width of the
`wire, in cross-section, is at least twice its thickness. In some
`applications, the wire coil may include three distinct regions
`of differing pitch (and therefore flexibility). Also, a third
`tubular layer may be disposed along a proximal section of
`the inner and outer tubular layers (desirably between such
`layers), to provide such proximal section with greater
`stiffness.
`
`BACKGROUND OF THE INVENTION
`Catheters find a variety of applications in medical proce
`dures for providing access to selected locations within a
`bodily passageway or cavity. A particularly common appli
`cation of catheters is for intravascular access for the admin
`istration of drugs, fluids or occlusive devices. Infusion
`catheters typically are introduced in combination with a
`guiding catheter and a guide wire.
`Infusion catheters are typically placed percutaneously via
`the femoral artery, although other arterial or venous entries
`are also used. Infusion catheters have many applications in
`the peripheral, coronary and neurovasculature. These
`include delivery of chemotherapy drags, delivery of blood
`thinning agents to breakdown blood thrombosis, infusion of
`contrast media for fluoroscopic imaging, or delivery of
`devices for treating aneurysms and arteriovenous malforma
`tions. In all these applications, the ability to access very
`selective and remote arterial or venous locations is critical.
`Important performance characteristics of infusion cath
`eters utilized for these and similar purposes include distal
`flexibility, pushability over a guide wire, luminal fluid
`carrying capacity, kink-resistance, frictional characteristics
`of inner and outer surfaces, and distal tip radiopacity.
`Prior artinfusion catheters typically consist of tubes made
`of a polymeric materials, sometimes in combination with
`metallic reinforcement. Such catheters of the prior art, while
`providing adequate means to access vascular sites, have
`distinct disadvantages. Often they are fabricated from poly
`mers which soften somewhat when inserted into a body (due
`to the effects of temperature). In some applications (such as
`smaller, more tortuous arteries) it is desirable to construct
`the catheter from very flexible materials to facilitate
`advancement of catheters into such difficult access locations.
`As a result, however, such catheters can become more
`difficult to manipulate, have a tendency to kink and buckle,
`lack axial energy transmission (i.e., poor pushability) and
`can also tend to bind against the guiding catheter and/or
`guide wire. Catheter designs intended to minimize such
`deficiencies often must do so at the expense of flexibility,
`resulting in poor trackability (i.e., ability of the catheter to
`follow and conform to the curves of a guide wire without
`causing the guide wire to straighten out).
`Catheters have been made which provide different regions
`of flexibility - - - i.e., a stiffer proximal section and a more
`flexible distal section. Examples of such catheters include
`U.S. Pat No. 4464,176, which describes a catheter made of
`two layers of tubing, one of the layers being more flexible
`than the other and extending distally beyond the end of the
`other layer by a considerable distance. U.S. Pat. No. 4,739,
`768 shows a similar structure, and further suggests the use
`of three layers of tubing to construct a catheter with three
`different degrees of flexibility. Utilizing solely the thickness
`of the catheter wall to control flexibility requires, however,
`that the stiffer portion of the catheter be necessarily propor
`tionally thicker. Others have addressed this problem by
`
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`5,704,926
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`4
`the art will also recognize that when increased torque is
`applied to the catheter tubing 10 additional reinforcement in
`the form of multi-wire braiding, multifiliar windings and
`other metallic or nonmetallic reinforcement may be used.
`Materials and material types suitable for use as the tubing
`encapsulating material include:
`TABLE A
`MANUFACTURES
`(TRADE NAMES)
`B. F. Goodrich (Estane)
`DuPont (Hytrel)
`Dow (Pellathane)
`B. F. Goodrich (Estane)
`Thermedics (Tecoflex)
`DuPont (Pyraline)
`General Electric (Ultem)
`Mobay (Apec)
`Dow Corning (Silastic)
`Dow Corning (MDX-4159)
`Grace Co. (Hypol)
`
`MATERIALS
`(A) polyesterurethane:
`(B) polyetherurethane:
`(C) aliphatic polyurethane:
`(D) polyimide:
`(E) polyetherinide:
`(F) polycarbonate:
`(G) polysikoxane:
`(H) hydrophilic polyurethane:
`(I) polyvinyls:
`(J) latex:
`(K) hydroxy-ethyl methacrylate:
`(L) blends of the above materials:
`(M) other elastomers that can be carried
`in solvent.
`
`O
`
`15
`
`25
`
`3
`Catheters made in accordance with the invention prefer
`ably include an outer layer formed so as to enter into and
`substantially fill the interstices of the coil, thereby placing
`the outer layer in intimate contact with the inner layer. This
`construction gives the catheter structural integrity greater
`than, for example a catheter made with an outer layer which
`has merely been shrunk over a reinforcing coil or braid.
`BRIEF DESCRIPTION OF THE DRAWTNGS
`FIG. 1 shows a catheter of the invention;
`FIG. 2 shows an enlarged, cross-sectional view of the
`catheter of FIG. 1;
`FIG. 3 shows in further enlarged detail the distal end of a
`catheter of the invention;
`FIG. 4 is a view similar to FIG. 2, depicting an alternate
`embodiment of the invention; and
`FIG. 5 is a perspective view of a preferred wire coil
`utilized in a catheter of the invention.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`Referring to FIG. 1, a catheter of the invention is com
`prised of an elongated tubular member 10, having substan
`tially circular (in cross-section) inside and outside walls
`which are preferably substantially smooth. The tubular
`member 10 is secured at its proximal end to a suitable Luer
`fitting 12. Tubular member 10 is comprised of an encapsu
`lating material and an encapsulated wire coil 14 as shown in
`FIGS. 2-5. The reinforcement provided by the wire coil
`enables the catheter to resist kinking and collapse, as well as
`the ability to better withstand the hoop stresses of any
`internal pressure. The helically wound wire coil also pro
`vides this reinforcement while preserving significant flex
`ibility of the catheter. Moreover, such flexibility can be
`controlled by varying the pitch of the coil - - - a smaller pitch
`(i.e. tighter spacing of successive turns of the wire coil)
`provides relatively less flexibility with greater pushability,
`while a larger pitch (i.e., wider spacing of successive turns
`of the wire coil) provides relatively greater flexibility with
`better trackability, though somewhat less pushability.
`Although the drawings, which are somewhat schematic,
`show varying pitches for the wire turns, as described below,
`preferably the wire coil is wound with a rather tight pitch in
`the proximal section of the catheter to provide good axial
`compressive strength (and therefore good pushability). This
`pitch is desirably no more than about 150% of the cross
`sectional width of the wire, and preferably less than about
`125% of such cross-sectional width.
`The coil pitch in a distal section of the catheter is larger,
`to provide greater flexibility and trackability to the distal
`portion of the catheter. Desirably the pitch of the distal
`section of the wire is between 150% and 300% of the
`cross-sectional width of the wire. In a particularly preferred
`embodiment utilizing 0.001x0.003" rectangular wire, the
`pitch of the wire coil in the proximal section is about
`0.0035" and the pitch of the wire coil in the distal section is
`about 0.007". By using the very same, continuous wire to
`provide varying flexibility to the catheter, manufacturing
`and quality control processes are simplified in comparison to
`other techniques which rely on joining sections of different
`stiffness materials, such as different stiffness tubing and/or
`different stiffness metal reinforcing structures.
`The encapsulating material may be a single layer of
`suitable flexible material, but more preferably is multi
`layered, as shown in the drawings. The materials of choice
`include elastomers such as polyurethane or silicone robber.
`Different materials will result in various levels offlexibility,
`pushability, trackability and kink resistance. Those skilled in
`
`30
`
`35
`
`The above-listed materials when used alone or as com
`ponents in a blend of materials have displayed excellent
`performance in robing manufactured by Navarre Biomedical
`Ltd. of Minnesota. The subsequent products produced with
`these materials allow for a range of performance character
`istics. Some of the blends of materials discussed below offer
`specific performance advantages.
`In the present invention these materials have been suc
`cessfully used to manufacture thin walled encapsulating
`robe. These materials desirably are prepared with a solvent
`system manufacturing process according to the following
`proportions listed in Table B. The materials listed herein are
`by way of illustration and not by way of limitation. Similar
`materials known to those skilled in the art having equivalent
`properties may also be used.
`
`45
`
`50
`
`55
`
`(A) urethanes;
`
`TABLEB
`
`solids:
`solvents:
`
`(B) polyimide:
`
`(C) polyetherimide
`
`(D) polycarbonate:
`
`(E) polysiloxane:
`
`(F) hydrophilic polyurethane:
`
`viscosity:
`solids:
`solvents:
`
`viscosity:
`solids:
`solvents:
`viscosity:
`solids:
`solvents;
`viscosity:
`solids:
`solvents:
`viscosity:
`solids:
`solvents:
`viscosity:
`
`69 to 14%
`THF/DMF 85/15
`(THF
`Tetrahydrofuran,
`DMF-Dimethyl
`formamide)
`10-100 centistokes
`20%.45%
`N
`Methylpyrrollidone
`80-1000 centistokes
`89 to 12
`methylene chloride
`40-100 centistokes
`6% to 12%
`THFDMF 85/15
`10-60 centistokes
`30%-60%
`111-trichloroethane
`100-450 centistokes
`196-95%
`water
`not applicable
`
`65
`
`The preparation of the encapsulating materials may be
`accomplished as follows. The solvent is added to the solid or
`liquid material in the appropriate mount to make the desired
`percent solids. Stirring is necessary to completely solvate
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`5,704,926
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`5
`plastic materials. Once the plastic is completely in solution
`the material is ready for use in coating applications for
`making the tubing of the invention. The encapsulating
`material 22 is configured to substantially cover the reinforc
`ing coil 14.
`FIG. 5 shows a schematic isometric drawing of an
`example of a reinforcing coil 14. The reinforcing coil 14 in
`the kink resistant tubing apparatus of the invention provides
`radial strength and hoop strength. The reinforcing coil 14
`helps retain the circularity of the tubing 10 and thereby
`avoids buckling and kinking of the tubing 10. The reinforc
`ing coil 14 also provides a crush-resistance to the reinforcing
`coil. The reinforcing coil 14 comprises a wire which may
`have various cross-sectional shapes, such as, for example,
`rectangular, circular, or elliptical. Those skilled in the art
`will recognize that the cross-sectional shapes will effect the
`load bearing characteristics and strength characteristics of
`the reinforcing coil 14. In the example of FIG. 5 the
`cross-section 52 is rectangular with a flat face 56 and flat
`body 58.
`Various different reinforcing coil 14 materials may be
`used. Further, the reinforcing coil dimensions can vary as
`well as the reinforcing coil 14 pitch and diameter. Listed
`below in Table C are some of the alternative coil 14 design
`parameters that can be used.
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`The coil wrapping process involves wrapping the reinforc
`ing coil wire 14 at the propertension and pitch. The coil wire
`is wrapped around the coated mandrel uniformly to the
`desired specifications. The coil's material composition, rota
`tional speed, tension, substrate diameter and pitch determine
`the size and flexibility of the coil. A conventional coil
`wrapping apparatus may be utilized for this function, such
`as, for example, an Accuwinder () machine as manufac
`tured by the Accuwinder Company of California. The coil
`wire 14 must be secured to the lead end of the mandrel
`substrate, as by an adhesive, or by spot welding two or,
`preferably, three successive turns of the coil together. The
`substrate is then wrapped from end to end using the prede
`termined coil wrapping parameters. In particular, the pitch of
`the coil is changed at the desired location along the length
`of the mandrel to produce a catheter having the desired
`flexibility requirements. Once the coil wrap is complete, the
`distal end of the coil 14 must be secured. This may be
`accomplished by suitable adhesives, or, preferably by spot
`welding two or, preferably, three successive turns of the coil
`together. FIG. 3 illustrates a spot weld 22 securing three
`adjacent turns of the distal end of the coil 14. After securing
`the end of the coil, the wire 14 can be cut and the coiled
`substrate removed from the machinery.
`The process variables for the coiling operation include the
`wire wrapping speed and coil wire tension. Wrapping speeds
`of between about 500 and 4000 rpm and coil wire tensions
`of between about 25 and 200 grams have worked well.
`After the coil has been suitably wrapped about the coated
`mandrel, a radiopaque marker 24 may be placed on or near
`the distal end of the coil, and encapsulating material may
`then be applied over the entire assembly. The coil 14 is over
`coated to a predetermined thickness using the solution draw
`process described below.
`The solution draw process is comprised of a number of
`steps. The first step is to prepare the encapsulating material
`in a solution form. The mandrel is drawn through the
`solution of the encapsulating material. The solution is held
`in a container having a hole slightly larger than the size of
`the mandrel. The mandrel is then drawn through the solution
`and the encapsulating material is deposited on the mandrel.
`The resulting encapsulating material thickness is highly
`controllable due to the propensity of the encapsulating
`material to adhere to the mandrel.
`After the proper thickness of encapsulating material has
`been applied, the mandrel and encapsulating material is
`cured for the appropriate time (determined based on the type
`of material used).
`Exemplary process variables are summarized as follows
`in Table D.
`
`TABLE C
`
`Coil Wire Size:
`Coil Wire Material:
`
`Col. Pitch:
`
`Coil Diameter:
`
`0.00-0015
`metals; stainless steel,
`MP35, NiTi, Tungsten,
`Platinum, kevalar, nylon,
`polyester, acrylic
`1-5 times maximum coil
`wire dimension (preferably
`1-2 times such dimension)
`0.010-0.375 inches
`
`35
`
`A preferred manufacturing method for constructing cath
`eters accordingly to the invention involves four major steps
`described in detail below: mandrel coating or overextruding,
`coil wrapping of mandrel substrate, over coating the coiled
`assembly, and mandrel extraction.
`Amandrel is first coated or overextruded with what will
`become the inner layer 20 (see FIG. 3) of the catheter. The
`mandrel provides the internal dimensions of the catheter,
`45
`and may be advantageously constructed from a fluoropoly
`mer such as PTFE or FEP polyethylene, nylon, or possibly
`a ductile metal such as silver, copper or nickel. The mandrel
`may be tubular or solid and may advantageously be dia
`metrically reduced upon the application of sufficient stretch
`ing force. If a tubing is used for the mandrel, a support rod,
`usually metallic, can be used to provide increased straight
`ness and stiffness.
`The mandrel may be coated with a thin layer or layers of
`a first encapsulating material (preferably PTFE or a similar
`low friction material) in solution form, using, e.g., the
`solution draw process described below. This can require one
`to several coats depending on tubing specifications and
`encapsulating material viscosity. Typically inner layers are
`coated to thicknesses of about 0.0005-0.005 inches. Solu
`tion draw rates of, e.g., 6-18 inches per minute can be used
`to apply the inner layer of encapsulating material. As indi
`cated above, the mandrel may alternately be overextruded
`with the inner layer of thermoplastic material, using well
`known thermoplastic extrusion techniques.
`After the inner layer 20 has been applied to the mandrel,
`the reinforcing coil 14 is wrapped onto this inner layer 20.
`
`50
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`55
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`
`Environmental
`
`Ambient temp;
`Humidity:
`Solution Wiscosity:
`Solution Draw Rate:
`Solvent Evaporation Rate:
`Solution Temp,
`Solution Chemistry
`
`TABLE D
`
`65°F-76 F.
`10-35% relative
`1-100 centistokes
`6-10 inches per minute
`14.5 using N-Butylacetate standard
`65 F-76 F.
`6%-14% solids (Such as Polyurethane
`in solution with highly polar solvents.)
`
`After the coating operation is completed, the mandrel may
`be suitably extracted, e.g., by securing each exposed termi
`nation of the mandrel and applying sufficient and direction
`ally opposite forces to plastically reduce the diameter of the
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`5,704,926
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`mandrel by 10-50%. Once this is accomplished, the mandrel
`can simply be removed from the tubing assembly.
`In one embodiment (depicted in FIGS. 1-2) the catheter
`is effectively divided into three segments, a proximal seg
`ment having a greater wall thickness, an intermediate seg
`ment having a lesser wall thickness but with the same coil
`pitch as the proximal segment, and a distal segment having
`the same wall thickness as the intermediate segment but with
`a larger coil pitch. Each segment of this catheter, therefore
`has a different flexibility. Alternately, a third degree of
`flexibility could be provided to a catheter by utilizing three
`(or more) different pitches in three different segments of the
`catheter.
`Particularly preferred dimensions of catheters constructed
`in accordance with the invention are in the size range of 2-6
`French, utilizing stainless steel wire (with a cross-sectional
`dimension of about 0.001x0.003" to about 0.002x0.005")
`wound about an inner layer of PTFE of a thickness of about
`0.002-0.003"; an outer encapsulating layer of Estane brand
`polyesterurethane coated to a thickness of about
`0.002-0.004" (preferably no more than about 0.01"); and an
`outer thin layer of a hydrophilic coating, such as the coatings
`described in U.S. Pat No. 4,847.324. Preferably the wire is
`wound in the proximal section of the catheter with a pitch of
`less than about 150% of the wire's cross-sectional width,
`and is wound in the distal section with a pitch of less than
`about five times its width, and preferably about two to three
`times its width. Catheters of such construction provide
`excellent flexibility, pushability, trackability, and have
`excellent kink-resistance.
`While a preferred embodiment of the present invention
`has been described, it should be understood that various
`changes, adaptations and modifications may be made therein
`without departing from the spirit of the invention and the
`scope of the appended claims.
`What is claimed is:
`1. A catheter capable of delivering drugs, fluids or occlu
`sive devices to a desired location in a bodily passageway or
`cavity comprising:
`a elongated cannula having proximal and distal ends and
`inner and outer tubular layers extending along substan
`tially the entire useable length of the elongated cannula;
`a proximal fitting secured to the proximal end of the
`elongated cannula;
`a continuous helical wire coil disposed between the
`tubular layers along substantially the entire useable
`length of the elongated cannula, the wire coil in a first
`section of the tubular layers having a first coil pitch,
`and the wire coil in a second section of the tubular
`layers having a second coil pitch which is larger than
`the first coil pitch to provide the second section of the
`tubular layers with greater flexibility than the first
`section.
`2. The catheter of claim 1 wherein the first section of the
`tubular layers is a proximal section and the second section
`of the tubular layers is a distal section.
`3. The catheter of claim 1 wherein the wire coil terminates
`in a distal end, both tubular layers of the catheter extending
`distally of the wire coil a distance not more than five times
`
`8
`the outer diameter of the tubular layers, measured at the
`distal end of the wire coil.
`4. The catheter of claim 3 further including a radiopaque
`marker disposed between the tubular layers at the distal end
`of wire coil.
`5. The catheter of claim 1 wherein the wire coil is made
`from a metal wire having a generally rectangular cross
`section.
`6. The catheter of claim 5 wherein the width of the wire,
`in cross-section, is at least twice its thickness.
`7. The catheter of claim 1 wherein the wire coil in a third
`section of the tubular layers, intermediate the first and
`second sections of the tubular layers, has a third coil pitch
`intermediate the coil pitches of the first and second sections
`of the tubular layers, providing an intermediate section of
`the tubular layers with a flexibility intermediate that of the
`first and second sections of the tubular layers.
`8. The catheter of claim 1 further including a third tubular
`layer disposed between the inner and outer tubular layers
`along a proximal section of the inner and outer tubular
`layers, to provide the proximal section with greater stiffness.
`9. The catheter of claim 1 wherein the second coil pitch
`is at least about 25% larger than the first coil pitch.
`10. The catheter of claim 1 wherein the second coil pitch
`is at least about 50% larger than the first coil pitch.
`11. The catheter of claim 1 wherein the first coil pitch is
`less than 150% of the cross-sectional width of the wire, and
`the second coil pitch is between 150% and 300% of the
`cross-sectional width of the wire.
`12. The catheter of claim 11 wherein the second coil pitch
`is at least about 25% larger than the first coil pitch.
`13. The catheter of claim 11 wherein the second coil pitch
`is at least about 50% larger than the first coil pitch.
`14. The catheter of claim 1 wherein the second section is
`at least about 5 cm in length.
`15. The catheter of claim 1 wherein the second section is
`at least about 15 cm in length.
`16. The catheter of claim 1 wherein at least one end of the
`helical wire coil is secured by a weld attaching two adjacent
`turns of the coil to each other.
`17. The catheter of claim 16 wherein the weld secures
`three adjacent turns to one another.
`18. The catheter of claim 16 wherein each end of the
`helical wire coil is secured by such a weld.
`19. The catheter of claim 1 wherein spaces between
`adjacent turns of the wire coil define interstices through
`which the outer tubular layer contacts the innertubular layer,
`thereby enhancing the structural integrity of the catheter.
`20. A catheter comprising an elongated tubular member
`defining a catheter lumen capable of receiving a guide wire
`therein, and a continuous helical wire coil embedded in the
`tubular member along substantially the entire useable length
`thereof, the wire coil in a first section of the tubular member
`having a first coil pitch, and the wire coil in a second section
`of the tubular member having a second coil pitch which is
`at least 25% greater than the first coil pitch to provide the
`second section of the tubular member with greater flexibility
`than the first section of the tubular member.
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`Page 8
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`Medtronic Exhibit 1472
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