PCT
`
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`lntemauonal Bureau
`
`éfiflb
`
`
`tartar;
`
`
`\f‘f'pl"
`.‘hlfl'c
`
`
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`
`(51) International Patent Cla$iflcation 5 :
`WO 97/37713
`(11) International Publication Number:
`
`
`
`A61M 25/00
`
`
`
` (43) International Publication Date:
`16 October 1997 (16.10.97)
`
`
`
`(21) International Application Number:
`PCTlUS97/05625
`
`
`(81) Designated States: AL, AM, AT, AU, AZ, BA, BB, BG, BR,
`
`BY, CA, CH, CN, CU, CZ, DE. DK, EE, ES, FI, GB, GE,
`3 April 1997 (03.04.97)
` (22) International Filing Date:
`
`
`HU, IL, IS, JP, KE, KG, KP, KR, [(2, LC, LK, LR. LS,
`
`
`LT, LU, LV, MD, MG, MK, MN. MW, MX, NO, NZ, PL,
`
`
`PT, RO, RU, SD, SE, SG, SI, SK, TJ, TM, TR, TT, UA,
`(30) Priority Data:
`
`
`
`UG, UZ. VN, ARIPO patent (GI-I, KE, LS, MW, SD, 82,
`US
`5 April 1996 (05.04.96)
`60/015,180
`
`
`UG), Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ,
`
`TM), European patent (AT, BE, CH, DE, DK, ES, FI, FR,
`
`GB, GR, IE, IT. LU. MC, NL, PT, SE), OAPI patent (BF,
`(71)(72) Applicant and Inventor: TRUCKAI, Csaba [US/US]; 627
`
`
`
`BJ, CF, CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG).
`Alberta Avenue, Sunnyvale, CA 94087 (US).
`
`Published
`
`(74) Agents: HAVERSTOCK. Thomas, B. et al.; Haverstock &
`
`
`Associates, Suite 420, 260 Sheridan Avenue, Palo Alto, CA
`With international search report.
`
`
`
`94306 (US).
`Before the expiration of the time limit for amending the
`claim and to be republished in the event of the receipt of
`
`amendments.
`
`
`
`
`(54) Title: THIN-WALLED AND BRAID-REINFORCED CATHETER
`
`
`
`(57) Abstract
`
`
`
`
`
`A flexible catheter comprising a reinforcement sheath made of helically disposed reinforcement elements, Different elements made
`
`
`of different material and having different thickness are used in different winding directions. By braiding thicker elements in a rotational
`
`
`direction, and by braiding substantially thinner elements in a counter-rotational direction, the kink-resistance, torsional stiffness and axial
`
`
`stiffness of the resulting catheter will be increased without increasing the catheter wall thickness. Thus, the same mechanical characteristics
`of catheters having thick catheter walls can be achieved in thin-walled catheters, greatly increasing the possible lumen diameter of the
`
`
`catheters. An even thinner catheter wall can be formed when the reinforcement elements are partially embedded into the wall of the inner
`
`
`tubular member.
`
`
`
`
`Page 1
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`Medtronic Exhibit 1447
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`Page 1
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`Medtronic Exhibit 1447
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`

`

`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States pany to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`Singapore
`
`Albania
`An-nenia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switurland
`Cbte d'lvoire
`Cameroon
`China
`Cuba
`Czech Republic
`Germany
`Denmark
`Estonia
`
`ES
`Fl
`FR
`GA
`GB
`GE
`6“
`GN
`GR
`HU
`IE
`IL
`[S
`['1‘
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungary
`ircland
`Israel
`Iceland
`ltaly
`Japan
`Kenya
`Kyrgyzstan
`Democratic People’s
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
`
`ML
`MN
`MR
`MW
`MX
`
`NL
`NO
`NZ
`PL
`[’1‘
`R0
`RU
`SD
`SE
`SG
`
`Lesotho
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`The former Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`
`8]
`SK
`SN
`52
`TD
`TG
`TJ
`TM
`TR
`TT
`UA
`UG
`US
`UZ
`VN
`YU
`ZW
`
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
`
`i
`
`Page 2
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`

`

`WO 97/37713
`
`PCT/US97/05625
`
`THIN-WALLED AND BRAID-REINFORCED CATHETER
`
`FIELD OF THE INVENTION
`
`The present invention generally relates to intravascular catheters, such as guiding
`catheters or diagnostic catheters used during percutaneous transluminal coronary
`angioplasty or microinvasive neuroradiology procedures, and any other catheters that can
`be introduced into a vasculature.
`
`BACKGROUND OF THE INVENTION
`
`With the advent of technology and surgical techniques, complicated surgical
`procedures such as transluminal coronary angioplasty and microinvasive neuroradiology
`have almost become routine for cardiologists and neuro-surgeons.
`In order to perform
`these procedures, as well as others such as laser angioplasty, angioscopy or intra-coronary
`atherectomy, it is necessary to introduce a catheter into an artery of the patient, and
`subsequently advance the catheter along the course of the artery or the other blood vessels
`
`to engage the target tissues. Surgical or diagnostic devices are often introduced within the
`catheter.
`
`5
`
`10
`
`15
`
`.Conventional catheters, however, have a small lumen diameter, thus limiting the
`size and complexity of the surgical or diagnostic devices that can be introduced. Those
`
`20
`
`catheter bodies are typically made of an inner plastic tube surrounded by and reinforced
`
`with a braided stainless steel mesh, and covered with an outer plastic sleeve. As shown in
`
`Figure 1, the braided steel mesh comprises helically disposed braid elements in both
`
`rotational and counter-rotational winding directions. Examples of such designs are
`disclosed in US. Patents 3,485,234 and 3,585,707. Those catheters are often
`
`25
`
`manufactured by extruding a plastic tubing, and then braiding metal fibers or strands over
`
`the plastic tubing to form a braided tube. The plastic tubing must be sufficiently thick to
`act as a base around which the braid is woven. A second extruded layer of plastic is then
`applied over the braided tube. Those catheters, however, while providing desirable
`
`mechanical characteristics. usually lack desirable wall thickness and lumen diameter.
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`WO 97/37713
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`PCT/US97/05625
`
`In order to develop catheters having a larger lumen diameter, catheter walls must
`
`be made as thin as possible. However, thin, under reinforced plastic tubing lacks desirable
`
`mechanical characteristics such as kink resistance, torsional stiffness and axial stiffness.
`
`An improved torsional stiffness permits torque to be better transmitted from a proximal
`
`5
`
`end of the catheter to a distal tip to facilitate advancement of the catheter through the
`
`10
`
`15
`
`20
`
`25
`
`branching blood vessels of the patient. A high kink resistance is also desirable because,
`
`once a catheter kinks, it will lose its functionality.
`
`In additional, a high axial stiffness is
`
`desirable because an axial force is sometimes necessary to push the catheter through long
`
`and winding blood vessels to engage the target tissue.
`
`Attempts have been made to optimize these mechanical characteristics. For
`example, in US. Patent 5,057,092 (Webster), a catheter comprising a flexible inner wall
`surrounded by a braided reinforcing mesh and a flexible plastic outer wall is disclosed.
`Webster, the braided reinforcing mesh is interwoven with longitudinal wrap members
`having a low modulus of elasticity to increase axial stiffness. Such a braided reinforcing
`mesh can increase torque and or axial stiffness of the catheter. However, a major
`drawback of such a design is that as more reinforcing elements are involved, catheter wall
`thickness is necessarily increased, thus reducing the lumen diameter. Furthermore, that
`mesh design does not enhance the torque performance or pushability of the catheter, since
`
`In
`
`identical braid members are used in both winding directions.
`Other examples include US. Patents 5,176,660 and 5,019,057, both authored by the
`applicant herein.
`In those patents, the applicant discloses a flexible catheter comprising a
`resilient, tubular layer in telescopic relation with a tubular sheath made of helically
`disposed strands.
`In that design, at least one of the helically disposed strands that are
`comprised of the tubular sheath is flat and has a width that substantially exceeds its height.
`Furthermore, to increase axial stiffness, the catheter also requires at least one axial
`reinforcing element. However, although such a braid reinforcement element can enhance
`torque response and axial stiffness of the catheter, that design does not reduce the wall
`thickness. Furthermore, it is important to note that the braided structure disclosed in these
`two patents comprises a plurality of flat and round elements that are wound in both
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`WO 97/37713
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`PCT/US97/05625
`
`5
`
`10
`
`15
`
`rotational and counter-rotational directions. Because of this disposition of braid elements,
`
`such a design does not increase the torque response and pushability of the catheter.
`
`Attempts have also been made to reduce wall thickness of prior art devices by
`reducing the thickness of the reinforcing elements and increasing their tensile strength.
`However, decreasing the diameter of the reinforcing elements will also decrease the kink
`resistance of the catheter.
`
`The relationship between the kink-resistance of a catheter and the diameter of the
`
`reinforcing elements can be described in the formula below:
`
`For a round reinforcing element:
`
`Imund= D4 x n / 64
`
`where D is the diameter of a round reinforcing element, and 1mm, is the kink resistance of
`
`the braided reinforcing sheath. And, for a rectangular reinforcing element:
`
`1,5,,“ng A3 x B / 12
`
`where A and B are the dimensions of a rectangular reinforcing element.
`
`Thus, decreasing the diameter or cross-sectional area of the reinforcing elements
`will reduce the kink resistance of the catheter. The increased tensile strength cannot
`
`compensate for the reduced kink-resistance of these constructions, and therefore, when
`
`sharply bent, a catheter constructed with thin reinforcing elements only will become
`
`excentric (collapse), reducing its torque performance. The catheter may also kink and lose
`
`20
`
`its functionality.
`
`25
`
`Other prior art devices attempted to reinforce the catheter with coil-like structures.
`
`However, coils tend to have good torque transmission only in one direction (in the
`winding direction). A rotational force applied opposite to the coil’s winding direction
`tends to open the coil structure, and therefore, the rotational force is not transmitted. Coil
`structures do not provide sufficient torque transmission capability because the reinforcing
`members are not interlaced with other reinforcing members. As a result, if a torque is
`applied to a proximal end of the coil structure. the coil will increase or decrease its
`
`nominal diameter depending on the direction of the torque, rather than transmitting the
`torque to a distal end.
`
`Page 5
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`

`

`WO 97/37713
`
`PCT/US97/05625
`
`None of the prior art devices above has a high torsional stiffness, a high axial
`
`stiffness and a high kink resistance without sacrificing wall thickness. What is needed is a
`
`flexible catheter having the largest possible lumen diameter without losing torsional
`
`stiffness, axial stiffness, and kink resistance.
`
`SUMMARY OF THE INVENTION
`
`An object of the present invention is to provide a reinforcement structure for and a
`
`method of constructing a catheter with minimum wall thickness and maximum axial
`
`stiffness, torsional stiffness, and kink-resistance.
`
`10
`
`In the preferred embodiment of the invention, a flexible catheter comprises at least
`
`one tubular member which is surrounded by a tubular sheath made of helically disposed
`
`crossing strands. The novelty in this invention is the use of braid elements having
`
`different thicknesses and/or different elasticities in different winding directions. By
`
`braiding thicker, higher bending modulus elements in a rotational direction, and by
`
`15
`
`braiding substantially thinner, higher elastic modulus elements in a counter-rotational
`
`direction, the torsional and axial stiffness of the resulting catheter will be increased
`
`without increasing the catheter wall thickness. Thus, the same mechanical characteristics
`
`of catheters having thick catheter wall can be achieved in thinner walled catheters, greatly
`
`increasing the possible lumen diameter of the catheters. Kink resistance is also increased
`
`20
`
`because, by interweaving smaller diameter elements with larger diameter elements, the
`
`larger elements are able to maintain a near—perfect helical shape, thus increasing the radial
`
`strength and kink resistance of the catheter. The high elastic modulus of the thinner
`
`elements keep the thicker elements in place to ensure uniform torque performance in both
`
`rotational and counter-rotational directions.
`
`25
`
`To further reduce the wall thickness, a catheter can be made such that some of the
`
`braid elements are partially embedded into the wall of the inner tubular member. Such a
`
`catheter can be manufactured by first applying a thin inner tubular member over a
`
`stretchable mandrel. Braid elements are then wound tightly around the thin inner tubular
`
`member to form a braided-tube/mandrel assembly. After an outer tubular member is
`
`30
`
`applied over the braided—tube/mandrel assembly, a tension is applied to the mandrel such
`
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`

`

`WO 97137713
`
`PCT/US97/05625
`
`that it is straightened. The braided tube and the outer tubular member are then fused
`
`together. The assembly is then cooled and the mandrel is stretched to a point such that its
`
`diameter is reduced. The constricted mandrel can then be readily removed and discarded.
`
`By using a stretchable mandrel, a thin walled inner tubular member can be used in spite of
`
`5
`
`the inward pressure resulting from the tight braiding. The step of stretching the mandrel,
`
`and thus reducing its diameter, allows the mandrel to be easily removed. This process also
`
`allows non-extrudable materials such as PTFE to be used for forming the inner tubular
`
`member.
`
`10
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Figure 1
`
`illustrates a prior art catheter reinforced with symmetrically disposed braid
`
`elements in both winding direction.
`
`Figure 2 illustrates a partial cut-away view of the preferred embodiment of the
`
`present invention.
`
`15
`
`Figure 3 illustrates a cross-sectionalview of the preferred embodiment of the
`
`present invention.
`
`Figure 4 illustrates the steps necessary for manufacturing the present invention.
`
`Figure 5 illustrates an alternate embodiment of the present invention where the
`
`braid elements are not partially embedded into the wall of the inner tubular member.
`
`20
`
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
`
`Figure 2 shows a telescopic view of the reinforced catheter in accordance with the
`
`present invention. A braided structure 204 is formed over an inner tubular member 202,
`
`and is encapsulated by an outer tubular member 206 to form a composite catheter body
`
`25
`
`200. All large diameter elements 212 of the braided reinforcement structure 204 are
`
`wound helically in a same rotational direction. All small diameter elements 214 of the
`
`braided structure 204 are interwoven with the large diameter elements 212 and are wound
`
`in a counter-rotational direction. The small diameter elements 214 and the large diameter
`
`elements 212 can be braided using methods known in the prior art. The large diameter
`
`30
`
`elements 212 are preferably made of metallic materials such as stainless steel, nitanol
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`WO 97/37713
`
`PCT/US97/05625
`
`alloy, copper or any other material suitable for braiding. The material would preferably
`
`have a high bending stiffness. Other materials such as carbon or fused silica fibers can
`
`also be used.
`
`It is not required that all the large diameter elements 212 are uniformly made of
`
`5
`
`one material. Depending on the intended application of the catheter and the desired
`
`mechanical characteristics, different combinations of large diameter elements 212 made of
`
`different materials may be used. Furthermore, it is not required that all large diameter
`
`elements have an identical diameter or cross-sectional area. Again, depending on the
`
`application of the catheter and the materials used, the large diameter elements 212 may
`
`10
`
`comprise filaments of different diameters, as long as they are substantially thicker than the
`
`small diameter elements 214,
`
`All small diameter elements 214 are wound helically in the counter-rotational
`
`direction and are interlaced with the large diameter elements to form the braided structure
`
`204. The small diameter elements 214 are made of preferably high tensile strength
`
`15
`
`materials, such as high tensile strength stainless steel, kevlar or any other metallic or non-
`
`metal suitable for braiding.
`
`It is not necessary that all the small diameter elements are
`
`made of a single material. Depending on the application of the catheter and the desired
`
`mechanical characteristics, the small diameter elements 214 may comprise a multitude of
`
`materials. Furthermore, the small diameter elements 214 may also comprise filaments of
`
`20
`
`different diameters, as long as they are substantially thinner than the large diameter
`
`elements 212.
`
`In this construction, the larger diameter elements with a bending stiffness are
`
`responsible for the maintaining the high kink resistance of the catheter. However, without
`
`the high tensile strength small diameter elements locking the large elements in place, the
`
`25
`
`large diameter elements will have poor torque performance when a counter-rotational force
`
`is applied. As discussed above, coils tend to have good torque transmission only in one
`
`direction (in the winding direction).
`
`In order to provide good torque performance and
`
`kink resistance, small diameter elements with high tensile strength are wound in the
`
`counter-rotational direction to keep the large diameter elements in place, assuring uniform
`
`30
`
`torque performance in both rotational and counter-rotational directions.
`
`Page 8
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`

`

`WO 97/37713
`
`PCT/US97/05625
`
`Figure 3 is a cross-sectional view of the preferred embodiment of the present
`invention. To further reduce catheter wall thickness, the braid elements 312 and 314 could
`
`be embedded at least partially into the wall of the inner tubular member 302.
`
`It is understood that the present invention is not intended to be limited by a cross-
`sectional shape of the braid elements. The figures, showing braid elements having a round
`cross-sectional shape. are intended for illustration purposes only.
`It is understood that
`braid elements having different cross-sectional shapes can also be used, and that they are
`also intended to be covered by this patent. Furthermore, it is also understood that round
`
`braid elements should have an oblong cross-sectional shape because the cross-section is
`made at an angle to the braid element. However, for the sake of simplicity, the cross-
`section of the braid elements are shown to be round.
`In addition, it is understood that the
`
`diagrams illustrate 8 large diameter elements interwoven with 8 small diameter elements
`
`for illustration purposes only. The number of large diameter elements and the number of
`
`small diameter elements do not have to be the same, and the number is not limited to 8.
`It should also be understood that large diameter elements have a larger bending stiffness
`than the small diameter elements.
`
`Figures 4a-c illustrate the steps which are necessary for the manufacture of the
`
`preferred embodiment of the present invention. According to Figure 4a. an inner tubular
`
`member 402 made of PTFE is placed over an annealed stretchable copper mandrel 401
`(or other suitable mandrel such as an annealed stainless steel mandrel) in such a way that
`both ends of the mandrel 401 extend out from the inner tubular member 402. Preferably,
`the inner tubular member 402 has been chemically etched for enhanced braiding
`capabilities. The mandrel 401 has a diameter approximately the same as an inside
`diameter of the inner tubular member 402. This assembly is fed into a braiding machine
`where braid elements 412 and 414 are braided tightly around the inner tubular member
`
`402. Preferably, the braiding can be sufficiently tight that some of the braid elements 412
`
`and 414 are partially embedded into the inner tubular member 402 to form a braided
`
`assembly 420, as shown in Figure 4b. After the braiding operation, an outer tubular
`
`member 406 is placed over the braided assembly 420 such that the outer tubular mandrel
`406 covers at least partially the inner tubular member 402, as shown in Figure 4c. The
`
`5
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`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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`WO 97/37713
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`PCT/US97/05625
`
`outer tubular member 406 can be constructed from thermoplastic elastomer such as nylons,
`
`methane, or other suitable materials. After the outer tubular member 406 is placed, a heat
`
`shrinkable tubing (such as FEP) is placed over the outer tubular member 406.
`
`Because the mandrel 401 is made of a stretchable material, the mandrel 401 is
`
`5
`
`malleable and by this time would be bent in several directions from handling during the
`
`braiding and tube assembly processes.
`
`If fusing occurs when the mandrel is bent, the
`
`resulting catheter will also be crooked. Therefore, it is necessary to straighten the mandrel
`
`401 before the final fusing process takes place. A straightening force can be applied in a
`
`fusing machine to straighten the mandrel 40]. However, the straightening force should be
`
`10
`
`small enough to prevent stretching the mandrel 401 to the point that would reduce its
`
`diameter more than 0.001". A heat process can be used to shrink the heat shrinkable
`
`tubing, melting and fusing the inner and outer tubular members together to a form a
`
`cohesive composite structure. After the fusing process and after the catheter is cooled to
`
`an ambient temperature, a second stretching force is applied to the mandrel 401 to reduce
`
`15
`
`its diameter so that it can be removed from the assembly. The heat shrunk tube can be
`
`removed by simply cutting it away. This process allows very thin materials such as PTFE
`
`to be made into the inner tubular member 402. This is because the mandrel 401 provides
`
`sufficient structure to support the braiding operation. Ordinarily, the pressure between the
`
`catheter structure and the mandrel would prevent ready removal of the mandrel. However,
`
`20
`
`in here, because a stretchable mandrel is used the catheter can be formed with the thin
`
`walled tubular members 402.
`
`Construction of the braided reinforcement sheath, however, is not limited to this
`
`manufacturing method. A continuous extrusion process can also be used. Using this
`
`method, a plastic inner tubular member is continuously extruded over a stretchable
`
`25
`
`mandrel wire. Then, reinforcing elements are braided over the plastic inner tubular
`
`member to form a braided assembly. The braided assembly is fed through a second
`
`extrusion machine where an outer tubular member is extruded over and fused with the
`
`braided assembly to form a composite structure. The stretchable mandrel can be stretched
`
`to a reduce its diameter such that the mandrel can be removed from the catheter lumen.
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`WO 97/37713
`
`PCT/US97/05625
`
`Figure 5 shows the cross-sectional view of an alternate embodiment of the present
`
`invention where reinforcing elements 512 and 514 are embedded into an outer tubular
`
`member 506, but are not embedded into an inner tubular member 502. The catheter in
`
`this case can be built in the following steps. A braided sheath is formed in a separate
`mandrel and is then transferred over an inner tubular member—metal mandrel assembly
`with very low tension on the individual braiding elements to prevent the braid to lock on
`
`to the stainless steel mandrel. An outer tubular member 506 at this point can be placed
`
`over the braid-inner tubular member-mandrel assembly. The outer tubular member 506
`
`will then be fused together with the inner tubular member-braided sheath-mandrel
`
`assembly with the help of a heated die or with the aid of a suitable heat shrinkable tubing.
`The heat shrinkable tubing can be removed after the fusing process (can be cut away too),
`
`and the stainless steel mandrel can be removed by pulling it out from the composite
`tubular structure.
`
`5
`
`10
`
`Many long-felt needs in the field of catheters have been fulfilled by the present
`
`15
`
`invention. A catheter made according to the present invention by interlacing thick
`
`braiding elements in one direction with thin braiding elements in an opposite direction
`
`allows thinner walled catheters to be made. Desirable mechanical characteristics such as
`
`torsional stiffness, axial stiffness and kink resistance can now be achieved without
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`sacrificing wall thickness. Furthermore, by braiding the braid elements over a stretchable
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`20
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`mandrel, wall thickness is further decreased because the braid elements can be partially
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`embedded into the inner tubular wall of the catheter. Thin, non-extrudable materials such
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`as PTFE may now be used to form the inner tubular member.
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`The present invention has been described in terms of specific embodiments
`
`incorporating details to facilitate the understanding of the principles of construction and
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`25
`
`operation of the invention. Such reference herein to specific embodiments and details
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`thereof is not intended to limit the scope of the claims appended hereto.
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`It will be
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`apparent to those skilled in the art that modifications may be made in the embodiment
`
`chosen for illustration without departing from the spirit and scope of the invention.
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`WO 97/37713
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`PCT/US97/05625
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`C L A I M S
`
`What is claimed is:
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`l
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`2
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`5
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`6
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`7
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`1
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`2
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`1
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`2
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`3
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`1
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`2
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`3
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`1
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`2
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`1
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`2
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`1.
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`A catheter for insertion into a human vasculature, comprising:
`
`a.
`
`b.
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`a first tubular member; and
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`a braided reinforcing sheath in concentric relation to the first tubular
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`member, the reinforcing sheath comprising a first strand interlaced with a
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`second strand, wherein the first strand is helically disposed in an opposite
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`winding direction to the second strand, wherein the first strand is
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`substantially thicker than the second strand.
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`2.
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`The catheter according to claim 1, further comprising a second tubular
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`member in concentric relation to and surrounding the braided reinforcing sheath.
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`3.
`
`The catheter according to claim 1, wherein the reinforcing sheath further
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`comprises a plurality of first strands interlaced with a plurality of second strands, each of
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`the first strands being helically disposed in a rotational winding direction, each of the
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`second strands being helically disposed in a counter-rotational winding direction.
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`4.
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`The catheter according to claim 3, wherein each of the plurality of first
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`strands is made of a first material and each of the plurality of second strands is made of a
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`second material.
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`5.
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`The catheter according to claim 4, wherein the first material has a higher
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`bending stiffness than the second material.
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`6.
`
`The catheter according to claim 4, wherein the first material is metallic and
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`the second material is non-metallic.
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`10
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`WO 97/37713
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`PCT/US97/05625
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`l
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`2
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`3
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`4
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`]
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`2
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`1
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`2
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`3
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`4
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`5
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`6
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`8
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`10
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`1
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`2
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`1
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`2
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`3
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`1
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`2
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`3
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`7.
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`The catheter according to claim 1, wherein the first strand is made of a first
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`material and the second strand is made of a second material, wherein the first material and
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`the second material have high elastic modula, further wherein the first material having a
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`higher bending stiffness than that of the second material.
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`8.
`
`The catheter according to claim 1, wherein the braided reinforcing sheath is
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`partially embedded into a wall of the inner tubular member.
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`9.
`
`A flexible, thin-walled and kink-resistant catheter for insertion into a human
`
`vasculature, comprising:
`
`a.
`
`b.
`
`an inner tubular member made of PTFE;
`
`a first plurality of strands helically interlacing in opposite winding directions
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`to a second plurality of strands to form a braided sheath, the first strands
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`and the second strands both being wound onto the inner tubular member,
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`wherein each of the first strands is substantially thicker than each of the
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`second strands; and
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`c,
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`an outer tubular member formed by fusing a second thermoplastic material
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`over the braided reinforcing sheath.
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`10.
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`The catheter according to claim 9, wherein the PTFE is formed over a
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`stretchable mandrel.
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`11.
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`The catheter according to claim 9, wherein the inner tubular member, the
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`braided reinforcing sheath, and the outer tubular member are fused together to form a
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`composite structure.
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`12.
`
`The catheter according to claim 9, wherein the first strands are made of a
`
`first material and the second strands are made of a second material, wherein the first
`
`material has a higher bending stiffness than the second material.
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`11
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`WO 97/37713
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`PCT/US97/05625
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`13.
`
`The catheter according to claim 12, wherein the first material and the
`
`second material have high elastic modula.
`
`14.
`
`A flexible, thin-walled and kink-resistant catheter for insertion into a human
`
`vasculature, comprising:
`
`a.
`
`b.
`
`an inner tubular member made of PTFE;
`
`a braided reinforcing sheath in concentric relation with the inner tubular
`
`member, the reinforcing sheath comprising a plurality of first strands
`
`helically interlaced with a plurality of second strands, each of the first
`
`strands being helically disposed in a first winding direction, each of the
`
`second strands being helically disposed in a second winding direction, each
`
`of the first strands being substantially thicker than each of the second
`
`strands, each of the first strands being made of a first material and each of
`
`the second strands being made of a second material, wherein the first
`
`material and the second material have a high elastic modulus, further
`
`wherein the first material has a higher bending stiffness than the second
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`material; and
`
`c.
`
`an outer tubular member.
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`15.
`
`A method of manufacturing a catheter for insertion into a human
`
`vasculature, comprising the steps of:
`
`a.
`
`placing a first tubular member over a stretchable mandrel, the stretchable
`
`mandrel having two ends, such that both ends of the stretchable mandrel
`
`extend out from the first tubular member, wherein the first tubular member
`
`is made of PTFE:
`
`b.
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`braiding reinforcement filaments over the first tubular member to form a
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`reinforcing mesh, the filaments being partially embedded into the first
`
`tubular member;
`
`c.
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`placing a second tubular member over the reinforcement mesh;
`
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`WO 97/37713
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`PCT/US97/05625
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`11
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`12
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`13
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`14
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`1
`2
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`3
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`1
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`2
`3
`4
`5
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`1
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`2
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`1
`2
`3
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`d.
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`e.
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`fusing the second tubular member to the reinforcement filaments and the
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`first tubular member; and
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`removing the mandrel by stretching the stretchable mandrel to reduce a
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`diameter of the stretchable mandrel.
`
`‘
`
`The method according to claim 15, further comprising the step of applying
`16.
`a tension to both ends of the stretchable mandrel to straighten the stretchable mandrel and
`
`the first tubular member prior to the step of fusing.
`
`17.
`
`The method according to claim 15, wherein the reinforcement filaments
`
`comprise a plurality of first strands helically interlaced with a plurality of second strands,
`each one of the first strands being helically disposed in a first winding direction, each one
`of the second strands being helically disposed in a second winding direction, further
`wherein each of the first strands is substantially thicker than each of the second strands.
`
`18.
`
`The method according to claim 17, wherein each of the first strands is made
`
`of a first material, wherein each of the second strands is made of a second material.
`
`The method according to claim 15, further comprising the step of cooling a
`19.
`fused assembly comprising the mandrel, the inner tubular member, the braided sheath, and
`the outer tubular member prior to the step of removing.
`
`13
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`WO 97/37713
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`l
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`15
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`16
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`20.
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`A method of forming a catheter, comprising:
`
`a.
`
`b.
`
`c.
`
`d.
`
`e.
`
`f.
`