(12) United States Patent
`Martin
`
`USOO6199262B1
`US 6,199,262 B1
`(10) Patent No.:
`Mar. 13, 2001
`(45) Date of Patent:
`
`(54) METHOD OF MAKING A GUIDING
`CATHETER
`
`(75) Inventor: Brian B. Martin, Boulder Creek, CA
`(US)
`
`(73) Assignee: Medtronic, Inc., Minneapolis, MN
`(US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(*) Notice:
`
`(21) Appl. No.: 09/258,657
`(22) Filed:
`Feb. 26, 1999
`Related U.S. Application Data
`
`(62) Division of application No. 08/915,360, filed on Aug. 20,
`1997, now Pat. No. 5,902,287.
`7
`(51) Int. Cl.' ...................................................... B23P 11/00
`(52) U.S. Cl. ....................... 29/525.15; 156/293; 156/257;
`264/544; 604/532; 604/525
`(58) Field of Search ..................................... 264/544, 264;
`604/526,532,525; 156/256, 257, 293,
`73.1, 308.2, 308.4; 29/469.5, 525.15
`References Cited
`U.S. PATENT DOCUMENTS
`3,752.617 3
`4,469,483
`4,576,772 *
`
`8/1973 Burlis et al. .
`9/1984 Becker et al. .
`3/1986 Carpenter.
`
`(56)
`
`sk -
`
`5/1986 Rosenkrantz et al. ............... 264/154
`4,590,028
`4,761,871 * 8/1988 O’Connor et al............... 29/431.2 X
`4,776.846
`10/1988 Wells.
`4,822,345
`4/1989 Danforth.
`4909,787
`3/1990 Danforth.
`4,976,691
`12/1990 Sahota.
`3: 1. Rerslag et al. .
`5,437,632
`8/1995 Engelson.
`5,453,099
`9/1995 Lee et al. .
`5,456,674
`10/1995 Bos et al..
`5,470,322
`11/1995 Horzewski et al..
`5,772,641 * 6/1998 Wilson.
`5,849,035 * 12/1998 Pathak et al..
`5,868,718 * 2/1999 Pepin et al..
`5,902,287 * 5/1999 R
`6,110,164 * 8/2000 Vidlund.
`cited by examiner
`Primary Examiner S. Thomas Hughes
`ASSistant Examiner Steven A Blount
`(57)
`ABSTRACT
`A method of making a catheter, including an elongated tube
`Structure having a proximal end and at least one preset
`curved portion proximate a distal end. The preset curved
`portion includes a first material located generally along an
`outer Surface of the preset curved portion and a Second
`material located generally along an inside Surface of the
`preset curved portion. The first material preferably has a
`greater stiffness than the second material, so that the catheter
`is capable of assuming a generally Straight configuration
`without plastic deformation.
`15 Claims, 3 Drawing Sheets
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`1
`METHOD OF MAKING A GUIDING
`CATHETER
`
`This is a division of application Ser. No. 08/915,360,
`filed Aug. 20, 1997, now U.S. Pat. No. 5,902,287, which is
`incorporated herein by reference.
`
`FIELD THE INVENTION
`The present invention relates to a guiding catheter that
`combines Stiffness that resists bending StreSS or torque and
`elasticity that permits Straightening without plastic defor
`mation.
`
`BACKGROUND OF INVENTION
`Medical catheters generally comprise elongated tube like
`members which may be inserted into the body either
`percutaneously, or via a body orifice, for any of a wide
`variety of diagnostic and therapeutic purposes. Such medical
`applications generally require the use of a catheter having
`the ability to turn corners, Such as in ocular irrigation or
`aspiration applications, or to negotiate twists and turns, Such
`as in certain cardiovascular applications.
`Catheters are typically introduced to the patients body
`through an introducer sheath. The catheter must generally be
`Straightened to fit through the introducer sheath. Therefore,
`the catheter must be constructed So that it is elastically
`resilient enough to go through the introducer sheath without
`plastic deformation, yet resilient enough to meet the perfor
`mance needs of the particular medical procedure.
`For Some applications, an inner catheter having a pre
`formed shape is Straightened and placed in an outer guiding
`sheath. When the inner catheter is extended or the outer
`sheath withdrawn, the inner catheter assumes its original
`shape. Again, the inner catheter must be constructed So that
`it is elastically resilient enough to Straighten without plastic
`deformation, yet resume its original configuration when the
`outer sheath is removed.
`For example, percutaneous translumenal coronary angio
`plasty (PTCA) requires manipulation of a catheter from a
`proximal position outside the patient's body through
`branched or tortuous portions of the patients arterial System
`for purposes of alleviating an obstruction by inflating a
`balloon. This particular procedure has been performed with
`increasing frequency over the past years in preference to
`open heart bypass Surgery.
`FIG. 1 illustrates the typical configuration of a conven
`tional left coronary guiding catheter 20 with a dilation
`balloon 24 in the aorta when engaged with a Stenosis 24 in
`the left main coronary artery during the performance of left
`coronary artery PTCA. The application of force 22 to
`advance a dilation balloon acroSS the region of Stenosis 26
`increases the bending stress 28 on the bend 30 of the guiding
`catheter 20. The pre-bent configuration of the guiding cath
`eter 20, in this situation a left Judkin's configuration, is
`unable to overcome the resistance at the Stenosis 24, causing
`distal end 32 to back away from the entrance of the left main
`coronary artery and the angioplasty balloon catheter 24 to
`prolapse in the accenting aorta, precluding further progreSS.
`Inability to advance the angioplasty balloon acroSS the
`coronary Stenosis because of instability of the guiding
`catheter and Subsequent prolapse of the angioplasty balloon
`catheter represents one of the most common reasons for
`failure during the performance of a coronary angioplasty
`procedure. The guiding catheter disengages in this circum
`stance because of its flexibility. The guiding catheter has
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`intrinsic flexibility because it must conform to the configu
`ration of the aorta and aortic arch, which contain both linear
`and curved Segments, during introduction. Insertion of the
`guiding catheter requires that it be advanced over a
`guidewire up the aorta, which is relatively Straight, and then
`over the aortic arch, which, as the name implies, is curvi
`linear.
`The stability afforded by guiding catheters typically
`relates to the limited intrinsic Stiffness of these catheters.
`The Stiffness of these prior guiding catheters is Subject to a
`“warm-up' phenomenon (becoming more flexible as they
`remain in the body and equilibrate to body temperature) and
`thus varies inversely with the temperature of the device.
`Hence, these catheters tend to be particularly Stiff on intro
`duction into the body, when flexibility is preferable, and yet
`relatively flexible and hence unstable following exposure to
`body temperatures during balloon catheter manipulation
`acroSS a coronary Stenosis when rigidity is preferable.
`U.S. Pat. No. 4,909,787 (Danforth) discloses a catheter
`having a closed chamber eccentrically disposed along
`almost the entire length of the housing Such that it virtually
`encompasses the housing. The catheter preferably contains a
`relatively elastic Segment disposed preferentially along the
`outer circumference of the curvature of the catheter. The
`chamber may be filled with a fluid. The catheter is capable
`of asymmetric elongation when hydrostatic pressure is
`applied to the chamber, resulting in the development of
`bending StreSS and increased rigidity on the distal end as
`desired by the operator.
`U.S. Pat. No. 5,456,674 (Bos et al.) discloses a catheter
`with variable longitudinal properties. The catheters are
`manufactured by Simultaneously conveying a plurality of
`Streams of different materials to a molding nozzle and
`merging the Streams together to form a catheter. The catheter
`is manufactured with varying properties along its longitu
`dinal axis corresponding to properties of the constituent
`Streams of materials.
`
`SUMMARY OF THE INVENTION
`The present invention relates to a catheter comprising an
`elongated tube Structure having a proximal end and at least
`one preset curved portion proximate a distal end. The preset
`curved portion comprising a first material located generally
`along an outer Surface on the Outer radius of the preset
`curved portion and a Second material located generally along
`an inner Surface on the inner radius of the preset curved
`portion. The present catheter is particularly useful as a
`guiding catheter that combines Stiffness to resist bending
`StreSS and elasticity to permit Straightening without plastic
`deformation.
`The first material preferably has a modulus of elasticity
`greater than the modulus of elasticity of the Second material.
`Alternatively, the modulus of elasticity of the Second mate
`rial may be greater than a modulus of elasticity of the first
`material. The first material preferably has a first stiffness
`greater than a Second Stiffness of the Second material. A third
`material may be interposed between the first and Second
`materials. The third material preferably has a third stiffness
`less than the first Stiffness, but greater than the Second
`stiffness.
`The preset curved portion is capable of assuming a
`generally Straight configuration without plastic deformation.
`The croSS Sectional area of at least a portion of the preset
`curved portion is about 50% of the first material and about
`50% of the second material. The first and the second
`materials are preferably coextruded Structure. Alternatively,
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`the first material is bonded to the Second material. An outer
`resilient layer may alternatively extend around the first and
`Second materials. In one embodiment, the one preset curved
`portion has a bend configuration Suitable for performing
`percutaneous coronary angioplasty.
`The present invention is also directed to a method of
`forming a catheter. The method includes the Step of forming
`an elongated tube Structure having a proximal end and at
`least one preset curved portion proximate a distal end. The
`preset curved portion comprises a first material located
`generally along an outer Surface of the preset curved portion
`and a Second material located generally along an inside
`Surface of the preset curved portion. In one embodiment, the
`Step of forming the elongated tube Structure includes inter
`posing a third material between the first and Second mate
`rials. The tube structure may be formed by coextrusion or
`joining discrete Segments of material.
`Stiffness refers to the ratio of a steady force acting on a
`deformable elastic medium to the resulting displacement.
`The modulus of elasticity refers to the ratio of the increment
`of Some specified form of StreSS to the increment of Some
`Specified form of Strain. In the catheter art, torque generally
`refers to a force that causes a catheter to kink or twist (torque
`failure). Bending stress refers to an internal tensile or
`compressive longitudinal StreSS developed in a member in
`response to a curvature induced by an external load or force.
`BRIEF DESCRIPTION OF THE DRAWING
`FIG. 1 is schematic illustration of the force that develops
`within a guiding catheter as an angioplasty dilation balloon
`catheter advances within the left coronary artery.
`FIG. 2 is a side view of a guiding catheter according to the
`present invention.
`FIG. 3 is a croSS Sectional view of the guiding catheter of
`FIG. 2.
`FIG. 4 is a side sectional view of the guiding catheter of
`FIG. 1 passing through an introducer sheath.
`FIG. 5A is a side view of an alternate guiding catheter
`according to the present invention.
`FIG. 5B is a cross sectional view of the guiding catheter
`of FIG. 5A.
`FIG. 6 is a Schematic illustration of a guiding catheter
`according to the present invention engaged with the left
`main coronary artery for manipulation of an angioplasty
`dilation balloon catheter acroSS a region of Stenosis.
`DETAILED DESCRIPTION OF THE
`INVENTION
`FIGS. 2 and 3 illustrate an exemplary catheter 40 made
`according to the present invention. The catheter 40 includes
`an elongated Structure 42 forming a lumen 43 which is
`generally Straight along a proximal portion 44. At least one
`preset curved portion 46 is located along a distal portion 48.
`The lumen 43 continues through the distal portion 48 of the
`elongated Structure 42. An outer Surface 50 located generally
`along the outer radius of the preset curved portion 46 is
`preferably constructed of a first material 52. An inner surface
`54 located generally along the inner radius of the preset
`curved portion 46 is constructed of a second material 56. In
`the embodiment of FIGS. 2 and 3, the proximal portion 44
`is also constructed from the Second material.
`The first material preferably has a greater stiffness (higher
`modulus of elasticity), and hence a greater resistance to
`bending StreSS or torque than the more elastic Second mate
`rial. Consequently, locating of the first material 52 along the
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`outer surface 50 reinforces the preset curved portion 46 so
`that it is better able to generally retain its shape even when
`subjected to a force 60. In an alternate embodiment, the
`locations of the first and second materials 52, 56 may be
`reversed.
`AS best illustrated in FIG. 3, the first material 52 accounts
`for about 50% of the cross sectional area of the catheter 40
`and the second material 56 accounts for the other 50%. It
`will be understood that the ratio of the first material to the
`Second material can vary depending on the design and
`application of the catheter 40, such as illustrated in FIGS. 5A
`and 5B. Additionally, it is possible that more than two
`different materials can be used for forming the present
`catheter. The first and second materials 52, 56 are preferably
`of different colorS So that the operator can distinguish the
`Stiffer portion from the more elastic portion.
`The present catheter achieves a useful balance of rigidity
`and flexibility with relatively thin wall thicknesses. Thinner
`walls 45 permits a larger inner lumen for a corresponding
`outer diameter. Although the thickness of the walls 45 will
`vary with the application of catheter 40, the wall thickness
`for a guiding catheter used for PTCA applications may be in
`the range of about 0.1 to 0.31 mm (0.004 to 0.012 inches).
`The lumen is preferably about 1.0 to 3.5 mm (0.038 to 0.138
`inches).
`A variety of polymeric material may be used for the
`present guiding catheter, Such as polyethylene,
`polypropylene, polyurethane, polyesters. In one
`embodiment, Pebax 7233 may be used for the first material
`52 and Pebax 6333 may be used for the second material 56.
`Pebax polymers are available from Elf Atochem located in
`Philadelphia, Pa. It will be understood that components of
`the catheter, (i.e., first and Second materials) are preferably
`Sufficiently compatible to be bonded together using
`adhesives, ultraSonic welding, heat fusion or coextrusion.
`Otherwise, the catheter designer is free to Select polymers
`that provide the optimum balance of StiffneSS and elasticity.
`FIG. 4 is a sectional view of the present catheter 40
`passing through an introducer sheath 62. The less elastic first
`material 52 is subjected to compressive forces 64 while the
`more elastic Second material 56 is Subjected to tensile forces
`66. Once the catheter 40 is removed from the introducer
`sheath 62, the preset curved portion will resume Substan
`tially its original shape. The compressive force 64 and
`tensile force 66 are preferably within the elastic range of the
`materials 52, 56. The first material 52 preferably responds
`with resiliency to compressive forces and the Second mate
`rial 56 preferably responds resiliently to tensile forces.
`Resilience refers to the ability of a strained body, by virtue
`of high yield Strength and relatively low elastic modulus, to
`recover its size and form following deformation. It will be
`understood, however, that for Some applications it may be
`desirable to subject the first material 52 and/or the second
`material 56 to forces Sufficient to cause plastic deformation.
`FIGS. 5A and 5B illustrate an altered catheter 40' con
`Structed according to the present invention. The outer Sur
`face 50' of the preset curved portion 46' is constructed of a
`first material 72. The inner surface 54" of the preset curved
`portion 46' is constructed of a Second material 74. A region
`between the first material and second material 72, 74 is
`constructed of a third material 76, which also forms the
`proximal portion 44' and the distal end 48 of the catheter 40'.
`In one embodiment, the second material 74 has the highest
`elasticity and the first material 72 the lowest elasticity
`(greatest stiffness), while the third material 76 has an inter
`mediate level of elasticity. As illustrated in FIG. 5B, an
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`elastic reinforcing member 70 may optionally extend around
`the preset curved portion 46' of the guiding catheter 40'.
`FIG. 6 is an illustration of the present guiding catheter
`configured for performing percutaneous transluminal coro
`nary angioplasty of the left main coronary artery. Although
`FIG. 6 illustrates a left Judkin's configuration guiding
`catheter, the invention is not confined to this configuration.
`The present guiding catheter can be applied to all configu
`rations of guiding catheters including left and right Judkins,
`Sones, Stertzer and Amplatz configurations. Related pro
`cedures that may utilize the present guiding catheter include
`laser angioplasty, angioscopy or atherectomy.
`The aorta 80 includes ascending portion 82 and a
`descending portion 84. The guiding catheter 86 is manipu
`lated up the descending aorta 84 and down the ascending
`aorta 82 so that the distal end 88 is within the coronar
`ostium, thus permitting Subsequent advancement of the
`angioplasty guide wire 90 and the balloon catheter 92 within
`the diseased vessel 94.
`Advancement of the balloon catheter 92 is typically
`resisted by regions of stenosis 96 in the diseased vessel 94.
`This resistance creates bending StreSS on the guiding catheter
`86, causing the preset curved portions 100, 102, 104 to
`deform. The preset curved portions 100-104 may be con
`structed to have a less elastic first material 106 located along
`the outer surface in each of the curves 100-104. During use
`of the guiding catheter 86, the less elastic material 106
`resists the compressive force associated with the bending
`StreSS generated by resistance to advancement of the balloon
`catheter 92. The material 108 on the inside Surface of the
`curve 100-104 preferably has a greater elasticity than the
`material 106 to facilitate introduction and removal of the
`guiding catheter 86 from the patient (see FIG. 4).
`Existing catheters are generally made as Stiff as possible,
`while Still providing Sufficient elasticity to permit the cath
`eter to be inserted through an introducer sheath. As a result
`of the required elasticity, Some catheters lack adequate
`Stiffness to effectively perform certain procedures once
`introduced into the body. The present guiding catheter
`provides Sufficient Stiffness to facilitate medical procedures,
`while minimizing the potential for catheter-induced vascular
`trauma associated with the introduction of the catheter.
`The present guiding catheter resists considerable bending
`StreSS at the distal aspect of the catheter to preserve the
`engagement of the guiding catheter within the coronary
`ostium during manipulation of the dilation balloon catheter.
`The incidence of vascular trauma Sustained during catheter
`introduction varies directly as a function of the relative
`stiffness of the catheter. The enhanced stability afforded by
`the present guiding catheter circumvents the need to force a
`relatively rigid guiding catheters of the prior art deep within
`a coronary lumen to achieve Stability, as well as the need for
`the sequential balloon technique. Thus, the flexibility of the
`present catheter contributes to the Safety of the procedure
`during both catheter introduction and balloon catheter
`manipulation.
`The catheter of the present invention may be constructed
`from a variety of techniques. The outer and inner Surfaces
`50, 54 may be assembled from segments of a tube structure
`using various bonding techniques, Such as ultraSonic
`welding, heat fusion or adhesives. In an embodiment where
`the guiding catheter is constructed from multiple discrete
`Segments, an outer reinforcing member 70 may be used to
`temporarily Secure the components in place or as a perma
`nent covering for the catheter 40'. The reinforcing member
`70 permits the use of materials that are incompatible or
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`otherwise do not adequately bond by adhesives or during
`coextrusion. In another embodiment of the present method,
`the first and Second materials of the present catheter may be
`coextruded using various methods, Such as disclosed in U.S.
`Pat. No. 5,456,674 (Bos et al.).
`The present method of coextrusion comprises forming an
`elongated tube Structure from first and Second materials. In
`one embodiment, it is possible to interpose a third material
`between the first and Second materials. The proximal and
`distal ends of the catheter may also be constructed from the
`third material. The ratio of the various materials may be
`adjusted during the coextrusion process.
`At least one preset curved portion is formed, preferably by
`thermoforming, proximate the distal end So that the leSS
`elastic first material located generally along an outer Surface
`of the preset curved portion and the more elastic Second
`material is located generally along an inside Surface of the
`preset curved portion. The distal end of the catheter may be
`formed into a variety of preformed shapes, Such as a shape
`Suitable for performing percutaneous coronary angioplasty.
`By selecting the first material to have a first stiffness
`greater than a Second Stiffness of the Second material, the
`preset curved portion is capable of resisting bending StreSS
`applied thereto, while being capable of assuming a generally
`Straight configuration without plastic deformation. The
`coextrusion proceSS permits that ratio of the two or more
`materials in the croSS Section of the catheter to vary accord
`ing to design requirements.
`Patents and patent applications disclosed herein, includ
`ing those disclosed in the background of the invention, are
`hereby incorporated by reference. Other embodiments of the
`invention are possible. It is to be understood that the above
`description is intended to be illustrative, and not restrictive.
`Many other embodiments will be apparent to those of skill
`in the art upon reviewing the above description. The Scope
`of the invention should, therefore, be determined with
`reference to the appended claims, along with the full Scope
`of equivalents to which Such claims are entitled.
`What is claimed is:
`1. A method of manufacturing a catheter, the method
`comprising:
`forming an elongated tube Structure comprising a proxi
`mal end, a distal end and at least one preset curved
`portion located between the proximal end and the distal
`end, the elongated tube Structure comprising a first
`material and a Second material, wherein the method
`further comprises:
`locating the first material along the preset curved portion,
`wherein the first material extends proximally and dis
`tally along the preset curved portion; and
`locating the Second material along the preset curved
`portion, wherein the Second material extends proxi
`mally and distally along the preset curved portion, and
`further wherein the second material extends beyond the
`first material both proximally and distally.
`2. The method of claim 1 wherein the first material
`comprises a modulus of elasticity greater than a modulus of
`activity of the Second material.
`3. The method of claim 1 wherein the second material
`comprises a modulus of elasticity greater than a modulus of
`elasticity of the first material.
`4. The method of claim 1 wherein the first material
`comprises a first StiffneSS and the Second material comprises
`a Second Stiffness less than the first Stiffness.
`5. The method of claim 1 further comprising locating a
`third material between the first and Second materials.
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`6. The method of claim 5 wherein the first material
`comprises a first Stiffness, the Second material comprises a
`Second stiffness less than the first stiffness, and the third
`material comprises a third Stiffness less than the first StiffneSS
`but greater than the Second Stiffness.
`7. The method of claim 1 wherein at least a portion of the
`preset curved portion of the catheter has a croSS Sectional
`area comprising about 50% of the first material and about
`50% of the second material.
`8. The method of claim 1 wherein manufacturing the
`catheter comprises coextruding the first and Second materi
`als.
`9. The method of claim 1 wherein manufacturing the
`catheter comprises attaching the first material to the Second
`material by ultraSonic welding.
`10. The method of claim 1 wherein manufacturing the
`catheter comprises fusing the first material to the Second
`material.
`11. The method of claim 1 wherein manufacturing the
`catheter comprises adhesively attaching the first material to
`the Second material.
`12. The method of claim 1 wherein the at least one preset
`curved portion is formed by thermoforming.
`13. The method of claim 1 further comprising securing the
`first and Second materials with an Outer reinforcing member.
`14. A method of manufacturing a catheter, the method
`comprising:
`forming an elongated tube Structure comprising a proxi
`mal end, a distal end and at least one preset curved
`portion located between the proximal end and the distal
`end, the elongated tube Structure comprising a first
`material having a first Stiffness and a Second material
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`having a Second Stiffness less than the first Stiffness,
`wherein the method further comprises:
`locating the first material along the preset curved portion
`Such that it extends both proximally and distally along
`the preset curved portion; and
`locating the Second material along the preset curved
`portion So that the catheter is capable of assuming a
`generally Straight configuration without plastic
`deformation, the Second material extending both proxi
`mally and distally from the preset curved portion Such
`that it extends beyond the first material both proximally
`and distally.
`15. A method of manufacturing a catheter, the method
`comprising:
`forming an elongated tube Structure comprising a proxi
`mal end, a distal end and at least one preset curved
`portion located between the proximal end and the distal
`end, the elongated tube Structure comprising a first
`material, a Second material, and a third material,
`wherein the method further comprises:
`locating the first material along the preset curved portion,
`wherein the first material extends proximally and dis
`tally along the preset curved portion;
`locating the Second material along the preset curved
`portion, wherein the Second material extends proxi
`mally and distally along the preset curved portion, and
`further wherein the second material extends beyond the
`first material both proximally and distally; and
`locating the third material between the first material and
`the Second material.
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