(12)
`
`United States Patent
`G00din et al.
`
`USOO6361529B1
`(10) Patent No.:
`US 6,361,529 B1
`(45) Date of Patent:
`*Mar. 26, 2002
`
`(54) STIFFENING MEMBER IN A RAPID
`EXCHANGE DILATION CATHETER
`
`(75) Inventors: Rich L. Goodin, Blaine; Suranjan
`Roychowdhury, Minneapolis;
`Katherine Prindle, Robbinsdale, all of
`MN (US)
`(73) Assignee: Schneider (USA) Inc., Maple Grove,
`MN (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`This patent is Subject to a terminal dis
`claimer.
`
`(*) Notice:
`
`(21) Appl. No.: 09/576,782
`(22) Filed:
`May 23, 2000
`Related U.S. Application Data
`(63) Continuation of application No. 09/150,463, filed on Sep. 9,
`1998, now Pat. No. 6,066,114.
`(51) Int. Cl. ............................................... A61M 25/00
`(52) U.S. Cl. ............... 604/524; 604/102.02; 604/96.01;
`606/194
`(58) Field of Search ......................... 604/96.01, 102.01,
`604/102.02, 103, 523, 524; 606/192, 194
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,137,906 A 2/1979 Akiyama et al.
`4,748,982 A 6/1988 Horzewski et al.
`4,762,129 A 8/1988 Bonzel
`4,943.278 A 7/1990 Euteneuer et al.
`B14,762,129 A 7/1991 Bonzel
`5,154,725 A 10/1992 Leopold
`5,156,594. A 10/1992 Keith
`5,328,472 A 7/1994 Steinke et al.
`5,413,559 A 5/1995 Sirhan et al.
`5,489,271 A 2/1996 Andersen
`
`
`
`8/1996 Steinke et al.
`5,549,557 A
`5,605,543 A 2/1997 Swanson
`5,607,394 A 3/1997 Andersen et al.
`5,634.902 A 6/1997 Johnson et al.
`5,658.251 A 8/1997 Ressemann et al. ... 604/102.01
`5,728,067 A 3/1998 Enger
`5,882,336 A 3/1999 Janacek
`5,921,958 A 7/1999 Ressemann et al. ..... 604/96.01
`6,066,114 A 5/2000 Goodin et al.
`
`FOREIGN PATENT DOCUMENTS
`
`WO
`
`92/17236
`
`10/1992
`
`Primary Examiner Richard K. Seidel
`Assistant Examiner Jeremy Thissell
`(74) Attorney, Agent, or Firm-Scimed Life Systems, Inc.
`(57)
`ABSTRACT
`A dilation catheter having a first shaft Section, a Second shaft
`Section attached to the first shaft Section, and an inflatable
`balloon attached to the Second shaft Section. A fluid pathway
`is defined through the catheter for inflation of the balloon. A
`guide wire lumen is provided in the Second shaft Section that
`can extend between the distal end of the balloon and a point
`distal of the first shaft section. A stiffening member is
`provided within the second shaft section of the dilation
`catheter to provide additional stiffness to the second shaft
`Section. In a preferred embodiment, the Stiffening member is
`attached at the distal end of the first shaft section to occlude
`the hollow passage of the first shaft section. In this
`embodiment, the first shaft section farther includes a fluid
`port that is proximal of the Stiffening member and that
`extends between the hollow passage of the first shaft Section
`and the exterior of the first shaft section. The second shaft
`section overlaps the first shaft section so that the hollow
`passage of the Second shaft Section is in fluid communica
`tion with the fluid port of the first shaft section to define the
`fluid flow pathway. The stiffening member is free from fixed
`interconnection at its distal end, and includes a linear tapered
`region along a portion of its length to provide a gradient of
`Stiffness to the Second shaft Section along the length of the
`Stiffening member.
`
`6 Claims, 2 Drawing Sheets
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`Page 1
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`IPR2020-00126/-127/-128/-129/-130/-132/-134/-135/-136/-137/-138
`
`Medtronic Ex-1816
`Medtronic v. Teleflex
`
`

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`US. Patent
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`U.S. Patent
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`Mar. 26, 2002
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`1
`STIFFENING MEMBER IN A RAPID
`EXCHANGE DILATION CATHETER
`
`REFERENCE TO RELATED APPLICATION
`This application is a continuation of application Ser. No.
`09/150,463 filed on Sep. 9, 1998, now U.S. Pat. No. 6,066,
`114, and which is hereby incorporated by reference in its
`entirety.
`
`5
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`TECHNICAL FIELD
`The present invention relates generally to medical devices
`for insertion and advancement through a body lumen. In
`particular, the present invention is a balloon catheter having
`a Stiffening member for use in intravascular catheterization
`therapies.
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`15
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`BACKGROUND OF THE INVENTION
`Intravascular catheters are presently in wide clinical use
`for a variety of diagnostic and therapeutic purposes. Intra
`vascular catheterization therapies, Such as percutaneous
`transluminal coronary angioplasty (“PTCA”), have been
`developed as alternatives to bypass Surgery for treating
`vascular diseases or other conditions that occlude or reduce
`the lumen size of portions of a patient's vascular System. In
`particular, balloon angioplasty has proven to be a useful, and
`in many circumstances preferred, treatment for obstructive
`coronary diseases.
`In a typical PTCA procedure, a guide catheter is intro
`duced into a peripheral artery of a patient, Such as a femoral
`artery through an incision at the groin. The guide catheter is
`advanced through the femoral or other peripheral artery to a
`desired coronary Site. Typically, the guide catheter is
`advanced through the aorta until the distal end of the guide
`catheter is positioned adjacent to the coronary ostium for the
`coronary artery to be treated. A guide wire is introduced
`through the guide catheter, and a balloon dilation catheter is
`then introduced over the guide wire. More particularly, the
`guide wire is advanced past the distal end of the guide
`catheter within the lumen of the diseased vessel and manipu
`lated acroSS the region of Stenosis. The balloon dilation
`catheter is then advanced past the distal end of the guide
`catheter over the guide wire until the balloon is positioned
`across the region of stenosis. The balloon is then inflated by
`Supplying a fluid under pressure to the balloon through an
`inflation lumen in the balloon dilation catheter, which
`Stretches the diseased vessel to re-establish acceptable blood
`flow through the vessel. Intravascular therapeutic and diag
`nostic procedures utilizing dilation catheters, Such as PTCA,
`have achieved wide acceptance because of their effective
`neSS and because they involve a relatively minor Surgical
`procedure as compared to coronary bypass Surgery.
`Advancing a catheter to position a balloon acroSS a
`Stenotic lesion can be a difficult and time consuming task
`due to the tortuous passages through which the catheter must
`be navigated by a physician. The efficacy of Such procedures
`relies upon the balloon being precisely positioned at the
`desired location. Furthermore, catheters must be able to
`traverse tortuous pathways in a patient's vasculature in a
`manner as atraumatic to the patient as possible. To Satisfy
`these requirements, catheters must balance a number of
`competing design criteria. Specifically, catheters should
`have a Small profile to permit navigation through Small body
`lumens. The catheter must be axially Strong along its lon
`gitudinal length to give the catheter “pushability’ for trans
`mitting a longitudinal force along the catheter So a physician
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`can push the catheter through the vascular System to the
`Stenosis. At the same time, however, the catheter must be
`flexible so that the catheter has good “trackability” So as to
`be able to navigate the tortuous passages of a patient's
`vascular System.
`To Satisfy these competing design criteria, catheters typi
`cally have a stiff proximal portion and a flexible distal
`portion to which the inflation balloon is attached. The stiff
`proximal portion gives the catheter Sufficient axial and
`longitudinal Strength to give the catheter pushability, while
`the flexible distal portion permits the catheter to pass
`through tortuous, tight curvatures of the vasculature.
`One type of balloon dilation catheter, commonly referred
`to as an “over-the-wire” catheter, typically includes a Single
`lumen shaft that extends from the proximal end of the
`catheter to the distal end of the balloon. A guide wire is
`inserted into and extends along the length of the Single
`lumen shaft. The guide wire is used to Steer the catheter
`through the patient's vasculature by advancing the catheter
`over the previously inserted wire until the balloon is posi
`tioned at a desired treatment location. In this catheter, the
`guide wire must be inserted into and through the entire
`length of the dilation catheter prior to the catheter being
`inserted into a patient's vasculature. AS Such, the guide wire
`must protrude from the patient's body by a length greater
`than the length of the dilation catheter. Moreover, because
`the guide wire extends through the length of the catheter
`there is relatively large friction between the guide wire and
`the catheter. As a result, manipulation of an over-the-wire
`dilation catheter can be difficult.
`A catheter design that alleviates these shortcomings is
`referred to as a “rapid-exchange' catheter. An example of a
`rapid-exchange catheter is described in United States Patent
`Reexamination Certificate B1 4,762,129 to Bonzel, the
`entire disclosure of which is hereby incorporated by refer
`ence for all purposes.
`While catheters of the rapid-exchange type have been
`highly successful in PTCA procedures, the flexible distal
`portion of Such catheters may kink and/or buckle when the
`catheter is Subjected to high axial loads. A region of the
`catheter where Such kinking and buckling can occur is the
`interface between the stiff proximal portion and the flexible
`distal portion of the catheter due to the change in Stiffness at
`this interface. Attempts have been made to provide a struc
`ture that resists kinking and buckling in this region. Such
`structures are described in U.S. Pat. No. 5,156,594 to Keith,
`U.S. Pat. No. 5,658,251 to Ressemann et al, and U.S. Pat.
`No. 4,748,982 to Horzewski et al.
`There is a continuing need for improved catheters, how
`ever. In particular, a rapid-exchange catheter having a Stiff
`ening member that provides a gradually varying Stiffness at
`the interface between a stiff proximal portion and a flexible
`distal portion of the catheter is highly desirable. Such a
`Stiffening member should be efficient to manufacture and
`use, and should be effective in providing Sufficient StiffneSS
`to the interface between the proximal and distal portions of
`the catheter, while not unduly influencing the flexibility of
`the catheter.
`
`SUMMARY OF THE INVENTION
`The present invention is a dilation catheter for insertion
`into and advancement through a body lumen. In a first
`embodiment, the dilation catheter comprises a first shaft
`Section having a proximal end, a distal end, and a first
`stiffness. The first shaft section also includes a hollow
`passage along a length of the first shaft Section and a fluid
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`US 6,361,529 B1
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`3
`port proximal of the distal end of the first shaft section. The
`fluid port extends between the hollow passage and the
`exterior Surface of the first shaft section. In this manner the
`hollow passage and the fluid port permit fluid flow through
`a length of the first shaft Section. A Second shaft Section has
`a proximal end which is attached to the first Shaft Section at
`a region adjacent the distal end of the first shaft Section. The
`Second shaft Section further includes a distal portion and has
`a second stiffness that is less than the first stiffness of the first
`shaft Section. The Second Shaft Section includes a hollow
`passage along a length of the Second shaft Section that is in
`fluid communication with the fluid port of the first passage
`to define a fluid pathway between the length of the first shaft
`Section and the length of the Second shaft Section. A dilation
`member is attached to the distal portion of the second shaft
`Section and is fluidly coupled to the hollow passage of the
`length of the Second shaft Section. In this manner, the
`dilation member receives fluid.
`The dilation catheter further includes a guide wire lumen
`in at least a portion of the Second shaft Section. The guide
`wire lumen includes a proximal end that extends through the
`Second shaft Section at a location distal of the first shaft
`Section. The guide wire lumen permits the insertion of a
`guide wire into the lumen. A Stiffening member is further
`provided in the dilation catheter. The stiffening member
`includes a proximal end that is attached to the distal end of
`the first shaft Section So as to occlude the hollow passage of
`the first shaft section at a location distal of the first shaft
`section fluid port. The stiffening member extends into the
`hollow passage of the Second shaft Section to provide
`additional stiffness to the second shaft section of the dilation
`catheter at a region along the length of the Stiffening
`member. The Stiffening member preferably includes a
`tapered region having a gradient of StiffneSS along its length
`to provide a gradient of Stiffness to the Second shaft Section.
`In a Second embodiment, the Stiffening member of the
`dilation catheter is a “floating member that is free from
`fixed interconnection with the first shaft section and the
`Second shaft section. The first shaft section includes the
`features of the first shaft section of the first embodiment
`described above, and further includes an axial Stop member
`that projects into the hollow passage of the length of the first
`shaft Section to arrest the axial motion of the Stiffening
`member in the proximal direction as the catheter is advanced
`in the body lumen. The stiffening member can have sub
`Stantially the same croSS Sectional shape and area as the
`hollow passage of the length of the first Shaft Section to
`occlude the hollow passage when it engages the axial Stop
`member. In this embodiment, the fluid pathway is defined by
`the hollow passage and fluid port of the first shaft Section,
`and by the hollow passage of the length of the Second shaft
`Section.
`In a third embodiment of the present invention, a balloon
`dilation catheter can include a Stiffening member that has a
`croSS Sectional area that is less than the croSS Sectional area
`of the hollow passage of a first shaft Section. In Such an
`embodiment, the fluid flow pathway through the dilation
`catheter is preferably substantially linear between the first
`and Second shaft Sections, and the first Shaft Section need not
`include a fluid port.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a side view of a dilation catheter in accordance
`with the present invention shown partially in Section to
`illustrate a Stiffening member in a Second shaft Section for
`providing additional Stiffness to the Second shaft Section as
`the catheter is advanced in a body lumen.
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`FIG. 2 is a side view of the stiffening member of the
`dilation catheter of FIG. 1.
`FIG. 3 is a detailed side view of a portion of the catheter
`of FIG. 1 shown in section to illustrate a first structure for
`attachment of the stiffening member to the first shaft section.
`FIG. 4 is an isometric view of a portion of a first shaft
`Section and a Stiffening member in accordance with the
`present invention showing a Second Structure for attaching
`the stiffening member to the first shaft section.
`FIG. 5 is an isometric view of a portion of a first shaft
`Section and a Stiffening member in accordance with the
`present invention showing a third structure for attaching the
`stiffening member to the first shaft section.
`FIG. 6 is a sectional view of a portion of a second
`embodiment of a dilation catheter in accordance with the
`present invention shown in Section to illustrate a floating
`Stiffening member in a Second shaft Section that is free from
`fixed attachment to a first shaft Section.
`FIG. 7 is a side sectional view of a portion of a third
`embodiment of a dilation catheter in accordance with the
`present invention having a floating Stiffening member.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`With reference to the Figures, and more specifically to
`FIGS. 1-3, a dilation catheter 10 in accordance with the
`present invention is shown. Dilation catheter 10 is com
`prised of a first shaft section 20, a second shaft section 30
`that is attached to the first shaft section, such as hypotube 20,
`and a dilation member, Such as inflatable balloon 60,
`attached to the second shaft section 30. Dilation catheter 10
`is adapted to be inserted into and advanced through a body
`lumen to position balloon 60 at a desired treatment site
`within a patient. Balloon 60 receives a fluid flow through
`catheter 10 for inflation of balloon 60 when positioned at the
`desired treatment location. In this manner, dilation catheter
`10 can be used to treat arterial and coronary diseases by
`re-establishing acceptable blood flow through a partially
`occluded body lumen in a patient's vasculature.
`Hypotube 20 of dilation catheter 10 includes a proximal
`end 22 and a distal end 24. Proximal end 22 is attached to
`a hub 21 in a conventional manner. Hypotube 20 includes a
`hollow passage, Such as lumen 26 (shown partially in
`phantom), along its length that is fluidly coupled to hub 21.
`Hub 21 can be attached to an external Source of fluid flow
`(not shown) to permit fluid flow into lumen 26 of hypotube
`2O.
`The second shaft section 30 includes a proximal end 32
`that is attached to hypotube 20 at a region adjacent to the
`distal end 24. Second shaft section 30 also includes a hollow
`passage, Such as lumen 36, along its length that is in fluid
`communication with the lumen 26 of the hypotube 20. A
`distal end 34 of second shaft section 30 is sealingly attached
`to balloon 60 in Such a manner that the lumen 36 of second
`shaft section 30 is fluidly coupled to balloon 60. In this
`manner, balloon 60 can receive fluid through the catheter 10
`for inflation of the balloon 60 at the desired treatment site
`within a patient's vasculature.
`In order to provide pushability to dilation catheter 10, a
`hypotube 20 is preferably used as the first shaft section in a
`known manner. Hypotube 20 is an elongated, thin walled
`metal tube, typically constructed of Stainless Steel, having
`lumen 26 along its length. Because of its thin walled
`construction, hypotube 20 provides a Small diameter Shaft
`Section to permit passage of catheter 10 through a Small
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`body lumen. The use of stainless steel for hypotube 20
`provides Sufficient axial Strength to deliver pushability to
`catheter 10. Hypotube 20 is also sufficiently flexible along
`its length due to its thin walled construction to permit
`navigation of dilation catheter 10 through arteries in a
`patient's vasculature, Such as the less tortuous regions of the
`femoral artery or the like. Other structures that provide the
`desired combination of flexibility and pushability can, of
`course, also be used.
`Second shaft section 30 is preferably constructed of a
`polymeric material So as to have a Stiffness that is less than
`the stiffness of the hypotube 20. In this manner, flexible shaft
`section 30 improves the trackability of dilation catheter 10.
`Proximal end 32 of second shaft section 30 overlaps and is
`attached to the hypotube 20 at a location that is adjacent the
`distal end 24. Lumen 36 of the second shaft section 30 thus
`preferably has a croSS Sectional area that is greater than the
`cross sectional area of the hypotube 20. In the embodiment
`shown, second shaft section 30 and hypotube 20 both have
`a circular croSS Sectional shape, although other shapes can,
`of course, be used. The second shaft section 30 thus pref
`erably has an inner diameter (i.e. the diameter of lumen 36)
`that is greater than the outer diameter of hypotube 20.
`Proximal end 32 of second shaft section 30 is positioned
`over the distal end 24 So as to overlap a region of hypotube
`20 adjacent distal end 24, and a seal 38 is created between
`the second shaft section 30 and the hypotube 20 at proximal
`end 32 in a conventional manner, Such as by heat shrinking
`the polymeric second shaft section 30 to hypotube 20 or
`using adhesive to Secure the Second shaft Section 30 to the
`hypotube 20.
`In the embodiment shown, dilation catheter 10 is a rapid
`exchange catheter, and thus includes a guide wire lumen 40
`in the second shaft section 30 to permit the insertion of a
`guide wire (not shown). The guide wire lumen 40 terminates
`at its proximal end 42 in a skive 44 positioned between the
`balloon 60 and the distal end 24 of the hypotube 20. In this
`manner, guide wire lumen 40 is positioned only in the
`Second shaft Section 30, and the guide wire thus does not
`have to extend as far out of a patient's lumen to permit the
`insertion of the catheter 10 over the guide wire. This, in turn,
`permits more rapid exchange between different catheters if
`necessary during a medical procedure, and reduces the
`frictional resistance between the guide wire and the dilation
`catheter 10 as compared to conventional, over-the-wire
`catheters.
`The guide wire lumen 40 extends through the balloon 60
`and terminates in a tip 46 at its distal end. In use, a guide
`wire is inserted into lumen 40 through tip 46 and exits skive
`44 of lumen 40. The guide wire provides a support structure
`for directing catheter 10 to the desired treatment location in
`a patient's vasculature. To aid in navigation of the
`vasculature, radiopaque markerS 62 are attached to the guide
`wire lumen 40 to permit the position of catheter 10 to be
`tracked radiographically during the insertion and advance
`ment of catheter 10 in the body lumen. The use of markers
`62 is generally known. The markerS 62 can be positioned at
`any known location in balloon 60, Such as at the mid point
`of the balloon 60, or symmetric with the mid-point of
`balloon 60. Markers 62 thus provide a precise indication of
`the position of the balloon 60 in a patient’s lumen.
`As perhaps best shown in FIG. 1, the second shaft section
`30 can be comprised of a proximal portion 70 and a distal
`portion 72. Proximal portion 70 can be formed from a
`polymeric material having a greater Stiffness than the distal
`portion 72. In this manner, the second shaft section 30 can
`have a varying degree of Stiffness to provide for better
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`trackability of catheter 10, thus aiding in navigation through
`the body lumen. Proximal portion 70 and distal portion 72
`can be attached at a butt joint 74 using conventional
`methods, Such as heat Sealing or adhesive. A convenient
`location for butt joint 74 is at the point where skive 44 of
`guide wire lumen 40 extends from the second shaft section
`30. Other methods for interconnecting proximal portion 70
`and distal portion 72 can of course be used, and the location
`for the interconnection can vary along the length of Second
`shaft section 30 as desired. Moreover, second shaft section
`30 can be comprised of additional, Separately formed por
`tions having different Stiffnesses to create a desired StiffneSS
`profile along the length of second shaft section 30.
`Dilation catheter 10 also includes a stiffening member 50
`that provides additional Stiffness to the Second Shaft Section
`30 along the length of the stiffening member 50. As
`described above, the hypotube 20 of catheter 10 is preferably
`formed from a relatively stiff material such as thin walled
`stainless steel, while the second shaft section 30 is formed
`from a more flexible, polymeric material. Such a construc
`tion balances the competing design criteria associated with
`catheters, namely providing axial Strength and pushability
`while being sufficiently flexible to navigate tortuous body
`lumens.
`AS described in the Background Section, known catheters
`can be Susceptible to buckling and kinking at the interface
`between a Stiff proximal Section, Such as hypotube 20, and
`a more flexible distal portion, Such as Second shaft Section
`30, as a guide wire is inserted in the catheter or as the
`catheter is advanced in a body lumen. This is primarily due
`to the abrupt change in Stiffness at the interface between the
`hypotube 20 and the second shaft section 30. To reduce the
`incidence of buckling or kinking, dilation catheter 10
`includes stiffening member 50 that provides additional stiff
`ness to the second shaft section 30 at the interface between
`hypotube 20 and second shaft section 30 and along the
`length of stiffening member 50.
`Stiffening member 50 is preferably formed from an
`elongated, thin StainleSS Steel wire. Other materials having
`appropriate mechanical characteristics can of course be
`used. Stiffening member 50 provides additional stiffness to
`the second shaft section 30 in an amount that is a function
`of the cross sectional area of stiffening member 50 at a
`specific location of stiffening member 50. That is, a stiffen
`ing member having a nominal croSS Sectional area at a first
`location along its length will provide a first amount of
`stiffness at this location, while less stiffness will be provided
`at other Selected locations along that length of the Stiffening
`member having a reduced croSS Sectional area. To provide a
`varying amount of stiffness, then, stiffening member 50 thus
`preferably includes portions having a reduced croSS Sec
`tional area as compared to the nominal croSS Sectional area
`of stiffening member 50.
`Specifically, in the embodiment shown, Stiffening mem
`ber 50 includes a first region 51 having a constant cross
`Sectional area along its length, and a tapered region 56
`having reduced croSS Sectional area that changes along the
`length of tapered region 56. Tapered region 56 extends from
`a first location 53 of nominal croSS Sectional area to distal
`end 54 of stiffening member 50, which has a reduced cross
`Sectional area that is less than the nominal croSS Sectional
`area. In the embodiment shown, the croSS Sectional area of
`stiffening member 50 decreases in a substantially linear
`manner along the length of tapered region 56 from first
`location 53 to distal end 54. In this manner, stiffening
`member 50 can be provided with a gradient of stiffness along
`the length of the tapered region 56, which in turn provides
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`7
`a gradient of additional stiffness to second shaft section 30
`along the length of the tapered region 56 of the Stiffening
`member 50. The reduced cross sectional area of tapered
`region 56 can be created by grinding down Stiffening mem
`ber along tapered region 56. Other methods for reducing the
`croSS Sectional area of Stiffening member 50 along tapered
`region 56 can also be used.
`While the cross sectional area of tapered region 56 is
`shown in FIGS. 1-3 as decreasing linearly along its length,
`the croSS Sectional area of tapered region 56 can vary in any
`manner desired, Such as having a Substantially constant
`reduced cross Sectional area (as compared to the nominal
`cross Sectional area) along the length of the tapered region,
`or having decreasing and increasing regions of croSS Sec
`tional area along tapered region 56. In addition, Stiffening
`member 50 can include any number of regions having
`reduced croSS Sectional area as compared to the nominal
`croSS Sectional area of Stiffening member 50, as is desired.
`Stiffening member 50 also preferably has a spherical
`member 57 at its distal end 54 that is greater than the cross
`Sectional area of distal end 54. Because of its reduced croSS
`Sectional area, Second Shaft Section 30 is Susceptible to being
`punctured by distal end 54 as the second shaft section is
`advanced through a tortuous Section of a patient's vascula
`ture. Spherical member 57, or some other blunt member
`affixed to the distal end 54 of stiffening member 50, helps to
`prevent the distal tip 54 from puncturing Second shaft
`Section 30.
`In the embodiment shown in FIGS. 1-3, the stiffening
`member 50 is fixedly attached to the distal end 24 of
`hypotube 20. The proximal end 52 of the stiffening member
`50 is inserted into the lumen 26 at distal end 24 of hypotube
`20, and is fixedly interconnected to the hypotube 20 through
`one or more crimps 48 (perhaps best shown in FIG. 3)
`formed in the hypotube 20. Crimps 48 can be evenly spaced
`about hypotube 24 if desired. Crimps 48 extend into the
`lumen 26 and contact the proximal end 52 of stiffening
`member 50. In this manner, a Secure interconnection
`between the hypotube 20 and the stiffening member 50 is a
`created. Other mechanisms for fixedly interconnecting Stiff
`ening member 50 to hypotube 20, A Such as adhesive or
`welding, can also be used. The fixed interconnection
`between stiffening member 50 and hypotube 20 creates a
`smoother stiffness gradient along the stiffening member 50,
`particularly through the tapered region 56 of the Stiffening
`member 50. In addition, the overall profile of stiffening
`member 50 in Such an embodiment remains the same as the
`bypotube 20, which can lead to more efficient use of catheter
`10.
`In this embodiment, the proximal end 52 of stiffening
`member 50 has the same croSS Sectional shape and area as
`lumen 26. As such, stiffening member 50 substantially
`occludes the lumen 26 of hypotube 20 at the distal end 24.
`To accommodate fluid flow through dilation catheter 10, a
`fluid port 28 is formed in the hypotube 20 to fluidly couple
`lumen 26 of hypotube 20 to lumen 36 of second shaft section
`30. Fluid port 28 is formed at a location that is proximal of
`the fixed interconnection of proximal end 52 of stiffening
`member 54 to hypotube 20 at crimps 48. Fluid port 28
`extends between lumen 26 and the exterior of the hypotube
`20. AS described above, the cross sectional area of lumen 36
`of Second shaft Section 30 is greater than the croSS Sectional
`area of hypotube 20, and second shaft 30 overlaps a region
`that is adjacent the distal end 24 of hypotube 20. In
`particular, second shaft section 30 overlaps fluid port 28, and
`seal 38 is formed at a location that is proximal of fluid port
`28. Fluid port 28 thus fluidly couples lumen 26 of hypotube
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`35
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`US 6,361,529 B1
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`15
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`20 to lumen 36 of second shaft section 30 and defines a fluid
`pathway along dilation catheter 10.
`FIG. 4 shows an alternative embodiment of the catheter
`structure for attaching a stiffening member 50' to a hypotube
`20'. A portion of hypotube 20' is removed through a
`longitudinal, U-shaped cut that is made at the distal end 24
`of hypotube 20'. Proximal end 52" (shown in phantom) of
`stiffening member 50' is inserted into hypotube 20'. The
`distal end 24 of hypotube 20' is then roll crimped about the
`proximal end 52" of stiffening member 50' to secure the
`stiffening member 50' to hypotube 20'. The roll crimp
`reduces the diameter of hypotube 20' in a region adjacent the
`distal end 24" of hypotube 20' to create a secure intercon
`nection between stiffening member 50' and hypotube 20'.
`The length and depth of the longitudinal, U-shaped cut in
`hypotube 20' is of sufficient size so that when hypotube 20
`is crimped about stiffening member 50', a fluid port 28' is
`formed in the hypotube 20". Fluid port 28' is in fluid
`communication with a passage in a Second shaft Section of
`a dilation catheter in a manner Similar to that described
`above.
`FIG. 5 shows a third embodiment of a catheter structure
`in a hypotube 20" for attaching stiffening member 50" to its
`distal end 24". The structure of FIG. 5 is similar to that
`shown in FIG. 4 in that a longitudinal, U-shaped cut is made
`at distal end 24", and distal end 24" is roll crimped about
`stiffening member 50". The longitudinal, U-shaped cut in
`hypotube 20" is deeper than that of hypotube 20', however,
`so that the distal end 24" of hypotube 20" does not fully
`extend around the proximal end 52" of stiffening member
`50". Solder 29 can be added at the top portion of hypotube
`20" to secure stiffening member 50" to hypotube 20". The
`shape of the U-shaped cut is again Such that, when hypotube
`20" is crimped about stiffening member 50", a fluid port 28"
`is created in hypotube 20".
`In a preferred embodiment, dilation catheter 10 has a total
`working length as measured from the proximal end 22 of the
`hypotube 20 to the tip 46 of the guide wire lumen 40 of
`approximately 59.25" (150.50 cm). The hypotube 20 is
`preferably formed from a length of stainless steel tube
`having a hollow diameter. The hypotube 20 is 45" (114.3
`cm) in length, and the outer diameter