BSC USP 8,048,032
`Exhibit 1014
`
`Page 1 of 10
`
`l|||||||||||||ll||l||||||||l||||||||||||||||||||||||||||||||l||||||||l||||||||||||||||||||
`
`US 20050004523A1
`
`(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2005/0004523 A1
`Osborne et al.
`(43) Pub. Date:
`Jan. 6, 2005
`
`(54) SMALL GAUGE NEEDLE
`CATHETERIZATION APPARATUS
`
`(75) Inventors: Thomas A. Osborne, Bloomington, IN
`(US); David G. Burton, Bloomington,
`IN (US)
`
`Correspondence Address:
`INDIANAPOLIS OFFICE 27879
`BRINKS HOFER GILSON & LIONE
`ONE INDIANA SQUARE, SUITE I600
`INDIANAPOLIS’ IN 462044033 (Us)
`
`(73) Assignee: Cook Incorporated
`_
`(21) Appl' NO"
`(22) Filed;
`
`10/879,409
`Jun_ 29, 2004
`
`Related US, Application Data
`
`(60) Provisional application No. 60/484,414, ?led on Jul.
`2, 2003.
`
`Publication Classi?cation
`
`(51) Int. Cl.7 .................................................. .. A61M 5/178
`(52) US. Cl. ...................................................... .. 604/164.01
`
`(57)
`
`ABSTRACT
`
`An apparatus for percutaneous catheterization. The appara
`tus comprises a catheter, and an inner cannula received
`Within the lumen of the catheter. The inner cannula has a
`distal portion that tapers toWard the distal end, and is sized
`to extend through the distal opening of the catheter to
`provide a generally smooth diametrical transition betWeen
`the distal end of the catheter and the distal open end of the
`inner cannula. Astiffening cannula is sized to be received in
`the lumen of the inner catheter, and has an inner diameter
`sized to receive a Wire guide therethrough. The stiffening
`cannula as a distal section of greater ?exibility than the
`?exibility of a proximal section for providing kink resistance
`to the apparatus.
`
`(16 10\ /12 ‘$6
`
`

`
`Page 2 of 10
`
`Patent Application Publication Jan. 6, 2005 Sheet 1 0f 3
`
`US 2005/0004523 A1
`
`2
`
`NH
`
`9
`
`cm
`
`mm
`
`

`
`Page 3 of 10
`
`Patent Application Publication Jan. 6, 2005 Sheet 2 0f 3
`
`US 2005/0004523 A1
`
`//////// /> /
`/mH
`
`

`
`Page 4 of 10
`
`Patent Application Publication Jan. 6, 2005 Sheet 3 0f 3
`
`US 2005/0004523 A1
`
`
`
`+55 NET/.5
`
`vm
`
`C
`
`R @E H: /
`
`v /////_//f
`
`

`
`Page 5 of 10
`
`US 2005/0004523 A1
`
`Jan. 6, 2005
`
`SMALL GAUGE NEEDLE CATHETERIZATION
`APPARATUS
`
`RELATED APPLICATION
`
`[0001] The present patent document claims the bene?t of
`the ?ling date under 35 U.S.C. §119(e) of Provisional US.
`Patent Application Ser. No. 60/484,414, ?led Jul. 2, 2003,
`Which is hereby incorporated by reference.
`
`BACKGROUND
`
`[0002] 1. Technical Field
`[0003] The present application relates to the ?eld of per
`cutaneous catheteriZation of blood vessels.
`[0004] 2. Background Information
`[0005] Many medical procedures require the percutaneous
`placement of a medical device, such as a catheter, in a vein
`or an artery. Such catheters are used for, among other things,
`blood pressure monitoring, blood sampling and the admin
`istration of drugs and ?uids to a patient.
`
`[0006] Typically, such catheters are introduced using the
`Well-knoWn Seldinger percutaneous entry technique. In the
`Seldinger technique, the physician makes an oblique entry
`into the vein or artery With a beveled needle. A Wire guide
`is then inserted through the bore of the needle about 5 to 10
`cm into the passageWay. The needle is thereafter WithdraWn,
`leaving the Wire guide in place. The catheter is inserted over
`the Wire guide, and advanced through the skin into the vein
`or artery at the needle puncture site. Once the catheter is in
`place, the Wire guide is WithdraWn.
`[0007] Conventional Wire guides are normally comprised
`of a tightly Wound helical stainless steel Wire coil. In order
`to have suf?cient rigidity to properly support and lead many
`standard catheters and other interventional devices, such
`Wire guides are typically constructed to have an outer
`diameter (O.D.) of about 0.035 or 0.038 inch (0.89 or 0.97
`The most common siZed needle used for initial vas
`cular access and introduction of a standard 0.035 or 0.038
`inch Wire guide is an 18 gauge (0.052 inch; 1.32 mm O.D.)
`thin-Walled needle. The 18 gauge needle has become the
`standard needle for use With the Seldinger technique for
`percutaneous catheteriZation. HoWever, the outer diameter
`of an 18 gauge needle is just large enough to cause bleeding
`or other organ damage if it does not enter the vessel
`correctly, or if it inadvertently penetrates some other organ.
`
`[0008] Because of the unavoidable tissue trauma that
`results from insertion of a needle, particularly a lancet
`beveled needle of the type commonly used in the Seldinger
`technique, it Would be desirable if a smaller needle could be
`used to effect the initial entry. A 22 or 21 gauge (0.028 inch
`or 0.032 inch; 0.72 mm or 0.81 mm O.D.) needle has an
`outer diameter that is small enough that regardless of Where
`the needle goes, only minimal, if any, complications are
`likely to occur. In addition, needles having smaller outer
`diameters (such as 22 or 21 gauge needles), are generally
`provided With a correspondingly shorter bevel at the needle
`tip compared to the siZe of the bevel tip of an 18 gauge
`needle. It is easier to get a short bevel into the lumen of a
`small vessel than the longer bevel of the 18 gauge needle.
`Unfortunately, hoWever, 22 and 21 gauge needles are not
`large enough to pass a standard 0.035 inch or 0.038 inch
`
`(0.89 mm or 0.97 mm) diameter Wire guide therethrough.
`The largest Wire guide that can be easily introduced into
`such small gauge needles is a Wire of 0.018 inch (0.46 mm)
`outer diameter. HoWever, as stated, many diagnostic and
`interventional devices need at least a 0.035 inch (0.89 mm),
`and more preferably a 0.038 inch (0.97 mm), diameter Wire
`guide to be able to optimally introduce and manipulate such
`devices through the vasculature.
`
`[0009] US. Pat. No. 4,650,472 (“the ’472 patent”),
`assigned to the assignee herein, describes a catheteriZation
`apparatus Which alloWs a smaller gauge needle, such as a 22
`gauge (0.028 inch; 0.72 mm O.D.) needle, to be used for
`percutaneous insertion of standard catheters and catheter
`introducing sheaths of up to a siZe of at least 9 French (0.118
`inch; 3.0
`The ’472 patent is incorporated by reference
`herein. In the apparatus described in the ’472 patent, a
`removable inner cannula is provided over the Wire guide but
`inside the catheter. This removable inner cannula has a
`tapered tip Which eXtends through the distal opening of the
`catheter, and provides a diametrical transition betWeen the
`large distal opening of the catheter and an 0.018 inch Wire
`guide. The inner cannula is about 0.038 inch (0.97 mm)
`OD, and the catheter is tapered to ?t over the inner cannula.
`The catheter and the inner cannula are inserted into the blood
`vessel in unison, Whereby the smooth diametrical transition
`of the leading end minimiZes the trauma that may otherWise
`be caused by the insertion of the large diameter catheter over
`the small diameter Wire guide in the absence of such a
`transition area. Once the catheter is properly positioned
`Within the blood vessel, the inner cannula and the smaller
`Wire guide can be WithdraWn, leaving the catheter in place.
`A 0.035 or a 0.038 inch (0.89 or 0.97 mm) Wire guide can
`then be introduced through the catheter and into the vessel.
`
`[0010] Thus, the apparatus of the ’472 patent can be
`successfully used to percutaneously insert a catheter into a
`blood vessel using a Wire guide and an introducer needle
`Which are much smaller in diameter than the distal opening
`of the catheter. This ensures good How characteristics for the
`catheter and a minimum of tissue trauma to the patient. It
`also alloWs for the introduction of larger diagnostic and
`interventional devices than Would otherWise be possible
`When an initial entry is made With a small diameter needle.
`
`[0011] In many cases When a catheter is to be inserted, it
`is necessary to make the puncture through tough, ?brous
`tissue, such as scar tissue, muscle tissue and the like. In such
`cases it is sometimes desired to further enhance the rigidity
`or column strength of a tWo-part dilator system such as that
`described in the ’472 patent, so that the apparatus can be
`more easily pushed through the puncture site and the vessel
`Wall. In order to enhance this rigidity, it is knoWn to position
`a thin needle stiffening cannula Within the lumen of the inner
`cannula of the apparatus of the ’472 patent. The stiffening
`cannula generally eXtends from the proXimal end of the
`apparatus up to about 1 or 2 mm proXimal of the distal end
`opening. This cannula provides eXtra stiffness to the appa
`ratus Without adding signi?cant bulk, complexity or addi
`tional parts.
`
`[0012] The apparatus described in the ’472 patent, as Well
`as the modi?ed apparatus that includes the stiffening can
`nula, are available from Cook Incorporated, of Bloomning
`ton, Ind., and sold under the trademark MICROPUNC
`TURE®.
`
`

`
`Page 6 of 10
`
`US 2005/0004523 A1
`
`Jan. 6, 2005
`
`[0013] The addition of the stiffening catheter adequately
`stiffens the tWo-part apparatus described in the ’472 patent
`device so that it can continue to be advanced in the vessel
`Without buckling When it meets resistance. The presence of
`the stiffening cannula, hoWever, may create an abrupt
`change in stiffness at the distal end of the apparatus, betWeen
`the relatively hard stiffening cannula and the much softer
`inner cannula. This abrupt change in stiffness may cause a
`kink to form When the distal tip of the apparatus is subjected
`to a bending force, such as When the catheter is attempting
`to negotiate a tight bend Within the vasculature. This prior art
`apparatus is shoWn in FIG. 6 of the present application. In
`the ?gure, a kink is shoWn at the distal portion 124 of inner
`cannula 120, immediately distal to the distal end of stiffen
`ing cannula 150. When an apparatus kinks in this manner,
`more resistance to insertion is created. As a result, the
`apparatus may become lodged and unable to be advanced
`further into the vessel. In severe cases, this abrupt transition
`may even result in the tip breaking off in the vessel.
`
`[0014] It is desired to provide an apparatus for percuta
`neous catheteriZation in a blood vessel that avoids the
`problems of the prior art. In particular, it is desired to
`provide an apparatus for percutaneous catheteriZation that
`has a ?exible distal end that avoids the abrupt change in
`stiffness in prior art devices. It is further desired to provide
`an apparatus for catheteriZation that is capable of alloWing
`the initial introduction to be made by a small diameter
`needle and a small diameter Wire guide, and yet enables a
`larger diameter Wire guide to be inserted following With
`draWal of the small diameter needle and a smaller Wire
`guide. It is further desired to provide such an apparatus that
`has suf?cient rigidity or column strength to enable the
`apparatus to readily pass through tough ?brous tissue, and
`that has a ?exible distal tip portion that avoids the abrupt
`transition of prior art devices.
`
`BRIEF SUMMARY
`
`[0015] The present invention provides an apparatus for
`percutaneous catheteriZation in a blood vessel that addresses
`the problems of the prior art devices described above.
`
`[0016] In one form of the present invention, the distal end
`of a stiffening cannula is modi?ed so that it has a gradual
`decrease in stiffness. The tip of the apparatus is made
`sufficiently ?exible to form a curve Without kinking or
`breaking at the transition point from the polymer tip to the
`distal end of the inner cannula. In another form of the present
`invention, an inner sleeve is added to the inside of a
`stiffening cannula. The sleeve may extend past the distal end
`of the stiffening cannula to the distal end of the inner
`cannula. This sleeve protects the edge of the distal end of the
`stiffening cannula, and adds support or kink resistance to the
`transition from the stiffening cannula to the tip of the inner
`cannula.
`
`[0017] Therefore, in one embodiment, there is provided an
`apparatus for percutaneous catheteriZation over a Wire
`guide. The apparatus comprises a catheter having proximal
`and distal open ends, and having a lumen extending longi
`tudinally therethrough. An inner cannula having proximal
`and distal open ends, and having a lumen extending longi
`tudinally therethrough, is siZed to be received Within the
`lumen of the catheter. The distal open end of the inner
`cannula is siZed to receive the Wire guide therethrough. The
`
`inner cannula has a generally linear main body portion and
`a tapered distal portion, Wherein the tapered distal portion
`has an outer diameter that decreases toWard the cannula
`distal end and is siZed to extend through the distal open end
`of the catheter to provide a generally smooth diametrical
`transition betWeen the catheter and the Wire guide. The
`apparatus further comprises a stiffening cannula having
`proximal and distal open ends, and having a lumen extend
`ing longitudinally therethrough. The lumen of the stiffening
`cannula is siZed to receive the Wire guide therethrough. The
`stiffening cannula is siZed to be received Within the lumen of
`the inner cannula, and extend along the generally linear body
`portion of the inner cannula to a terminal point. The stiff
`ening catheter has a distal section of greater ?exibility than
`the ?exibility of a proximal section of the stiffening catheter.
`[0018] In another embodiment, the present invention com
`prises an apparatus for percutaneous catheteriZation. The
`apparatus comprises a catheter having proximal and distal
`open ends, and having a lumen extending longitudinally
`therethrough. An inner cannula is provided having proximal
`and distal open ends, and having a lumen extending longi
`tudinally therethrough. The inner cannula is siZed to be
`received Within the lumen of the catheter, and the distal open
`end of the inner cannula is siZed to receive a Wire guide
`therethrough. The inner cannula has a generally linear main
`body portion and a tapered distal portion. The tapered distal
`portion has an outer diameter that decreases toWard the
`cannula distal end and is siZed to extend through the distal
`open end of the catheter to provide a generally smooth
`diametrical transition betWeen the catheter and the Wire
`guide. A stiffening cannula having proximal and distal open
`ends, and having a lumen extending longitudinally there
`through is provided. The stiffening cannula is siZed to be
`received Within the lumen of said inner catheter. An inner
`sleeve having proximal and distal open ends, and having a
`lumen extending longitudinally therethrough is provided.
`The lumen of the inner sleeve is siZed to receive the Wire
`guide therethrough. The inner sleeve is siZed to be received
`Within the lumen of the stiffening cannula, Wherein the inner
`sleeve distal end extends substantially to the distal opening
`of the inner cannula.
`[0019] In yet another embodiment, the present invention
`comprises a method of percutaneous catheteriZation. In the
`inventive method, a Wire guide is introduced into a vessel.
`A catheteriZation apparatus is provided. The catheteriZation
`apparatus comprises a catheter having a lumen extending
`longitudinally therethrough and having a distal end; an inner
`cannula having a lumen extending longitudinally there
`through, the inner cannula siZed to be received Within the
`lumen of the catheter, a distal end of the inner cannula
`tapering to a diameter just large enough to enable the Wire
`guide to pass freely therethrough, the tapered distal end
`providing a generally smooth diametrical transition betWeen
`the catheter and the Wire guide; and a stiffening cannula
`having a lumen extending longitudinally therethrough, the
`lumen of said stiffening cannula siZed to receive said Wire
`guide therethrough, the stiffening cannula being siZed to be
`received Within the lumen of said the catheter, the stiffening
`catheter having a distal section of greater ?exibility than the
`?exibility of a proximal section. The catheteriZation appa
`ratus is introduced into the vessel over the Wire guide. The
`Wire guide, inner cannula and stiffening cannula are then
`WithdraWn from the vessel, While maintaining the catheter in
`the vessel. If desired, a second Wire guide having a larger
`
`

`
`Page 7 of 10
`
`US 2005/0004523 A1
`
`Jan. 6, 2005
`
`outer diameter than the diameter of the ?rst Wire guide can
`then be inserted into the vessel through the lumen of the
`catheter following WithdraWal of the ?rst Wire guide, inner
`cannula and stiffening catheter. A medical device that
`requires a larger Wire guide can then be inserted into the
`vessel over the second Wire guide. As a result, a medical
`device that requires a large Wire guide for introduction into
`a vessel has been introduced even though an initial insertion
`is made With a small gauge needle and small Wire guide.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0020] FIG. 1 is an elevational vieW of an apparatus for
`percutaneous catheteriZation according to an embodiment of
`the present invention, shoWing a catheter and an inner
`cannula partially inserted into the catheter;
`
`[0021] FIG. 2 is an elevational vieW of the apparatus of
`FIG. 1, shoWing the inner cannula fully inserted into the
`catheter;
`[0022] FIG. 3 is an enlarged elevational vieW of the distal
`portion of the apparatus as shoWn in FIG. 2, and shoWing a
`Wire guide extending from the distal end of the cannula;
`
`[0023] FIG. 4 is a vieW of an embodiment of the present
`invention, Wherein the catheter and inner cannula are shoWn
`in longitudinal cross section, and the stiffening cannula is
`not in cross section;
`
`[0024] FIG. 5 illustrates the embodiment of FIG. 4 shoW
`ing the smooth transition betWeen the soft polymer tip and
`the stiff cannula When the distal tip of the apparatus is
`subjected to a bending force;
`
`[0025] FIG. 6 is a longitudinal cross-sectional vieW of a
`prior art apparatus for effecting percutaneous catheteriZa
`tion;
`[0026] FIG. 7 is a longitudinal cross-sectional vieW of
`another embodiment of the present invention shoWing the
`addition of an inner sleeve inside of the stiffening cannula.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`AND THE PRESENTLY PREFERRED
`EMBODIMENTS
`[0027] For purposes of promoting an understanding of the
`present invention, reference Will noW be made to the
`embodiments illustrated in the draWings, and speci?c lan
`guage Will be used to describe the same. It is nevertheless to
`be understood that no limitation of the scope of the invention
`is thereby intended, the proper scope of the invention being
`indicated by the claims appended beloW and the equivalents
`thereof. The ?gures are not all draWn to the same scale to
`avoid obscuring the details of the ?ner structures. The
`folloWing detailed description of the preferred embodiments
`Will make clear the preferred arrangement, siZe relationships
`and manner of using the components shoWn herein.
`
`[0028] Illustrated in FIG. 1 is an elevational vieW of an
`apparatus 10 for percutaneous catheteriZation. As shoWn in
`the vieW of FIG. 1, apparatus 10 includes a catheter 12 and
`an inner cannula 20. For convenience, the term “catheter” is
`used herein to refer to both catheters and catheter-introduc
`ing sheaths, as they are analogous structures for the purposes
`of this invention.
`
`[0029] In the vieW of FIG. 1, inner cannula 20 is shoWn
`partially inserted into catheter 12. During a particular point
`
`in the preferred method of use of the inventive apparatus,
`cannula 20 is more fully disposed Within catheter 12, as
`illustrated in FIG. 2 and as further discussed beloW. Pref
`erably, catheter 12 comprises a polymeric elongated tubular
`structure in the range, e.g., of about French siZe 3 to 9, and
`having a lumen extending longitudinally therethrough. Cath
`eter 12 is preferably formed of radiopaque polyethylene,
`although it can alternately be formed of materials such as
`polytetra?uoroethylene, vinyl, nylon, polyurethane and
`other conventional polymers and materials that are typically
`used for such purposes in the medical ?eld. Catheter 12 is
`con?gured With a slight taper at distal end 14 terminating at
`distal opening 18. Distal opening 18 is signi?cantly larger in
`diameter than Wire guide 30 (FIG. 3), With a diameter of
`about 0.039 inch (1 mm) being typical. Wire guide 30 Will
`typically have a diameter of about 0.018 inch (0.46
`
`[0030] Apparatus 10 further includes a hub 40 having a
`pair of radially protruding Wings 42, 44 ?xed to proximal
`end 16 of catheter 12, as Well as a standard Luer lock type
`connector 46. Wings 42, 44 can be used as anchor points for
`securing the catheter in place after it has been inserted, such
`as by taping them to the patient’s skin. Hub 40 has a
`passageWay therethrough in alignment With and communi
`cating With the lumen of catheter 12, the passageWay being
`at least as great in diameter as the lumen. The passageWay
`through hub 40 terminates in proximal opening 48.
`
`[0031] Also shoWn in FIG. 1 is inner cannula 20. Inner
`cannula 20 is siZed to ?t freely Within the lumen of catheter
`12. Cannula 20 is generally a soft polymeric tube having a
`lumen therethrough, the lumen of inner cannula 20 being
`siZed to receive Wire guide 30 freely therein. Attached to the
`proximal end of inner cannula 20 is connector hub 28 Which
`terminates in a Luer lock connector 22. Luer connector 22
`is con?gured to releasably engage and connect With Luer
`lock connector 46 to selectively maintain catheter 12 and
`cannula 20 in the ?xed longitudinal relationship With respect
`to each other shoWn in FIG. 2. Connector hub 28 and Luer
`lock connector 22 have a passageWay therethrough aligned
`With and communicating With the lumen of inner cannula 20.
`Hubs and connectors of the type described hereinabove With
`regard to catheter 12 and cannula 20 are Well knoWn in the
`medical arts, and need not be further described herein.
`
`[0032] Referring again to FIG. 2, inner cannula 20 is
`shoWn disposed fully Within catheter 12, and connector 22
`is engaged With connector 46. In this arrangement, the distal
`tip 24 of inner cannula 20 extends through distal opening 18
`of catheter 12. Inner cannula 20 terminates in distal opening
`26, Which is just slightly larger in diameter than Wire guide
`30, that is, it is just large enough to receive Wire guide 30
`freely therethrough.
`
`[0033] FIG. 3 is an enlarged vieW of the distal end of
`catheter 12 shoWing the relationship of the distal portions of
`catheter 12 and cannula 20 to Wire guide 30, When the
`catheter and cannula are engaged as in FIG. 2. Wire guide
`30 is shoWn disposed Within cannula 20 and extending
`through cannula distal opening 26. As can be seen, cannula
`tapered distal tip 24 provides a diametrical transition from
`distal opening 18 of catheter 12 to distal opening 26 of
`cannula 20. This provides a relatively smooth diametrical
`transition from Wire guide 30 to the maximum diameter of
`catheter 12, When Wire guide 30, cannula 20, and catheter 12
`are arranged as shoWn. A relatively smooth transition such
`
`

`
`Page 8 of 10
`
`US 2005/0004523 A1
`
`Jan. 6, 2005
`
`as that shown in the ?gure enables the apparatus to be
`percutaneously inserted into the vessel over the guide Wire,
`in a manner that avoids the presence of larger diameter free
`edges that Would otherWise be present at the site of the
`insertion.
`
`[0034] FIG. 4 shoWs the distal portion of the apparatus of
`FIG. 2 Wherein catheter 12 and inner cannula 20 are shoWn
`in longitudinal cross section, and stiffening cannula 50 is not
`in cross section. Stiffening cannula 50 is disposed Within the
`lumen of inner cannula 20, and extends to a terminal point
`that does not extend beyond the distal end of the inner
`cannula. Preferably, the terminal point is betWeen about 0.5
`and 10 mm short of (e.g., proximal to) the distal end of the
`inner cannula, and more preferably, betWeen about 1 and 2
`mm short of said distal end. The inner diameter of stiffening
`cannula 50 is just slightly larger in diameter than Wire guide
`30, to provide a secure ?t for stiffening cannula 50 Within the
`lumen of inner cannula 20.
`
`[0035] Stiffening cannula 50 is a needle-like elongated
`tube having suf?cient rigidity to assist apparatus 10 in
`passing through tough, ?brous tissue. Preferably, stiffening
`cannula 50 is made from a relatively stiff polymer, such as
`PET. Alternatively, stiffening cannula 50 can be formed from
`a metal such as stainless steel, from a metallic alloy such as
`nitinol, or from a ?ber composite material. Stiffening can
`nula 50 should be formed of a material that provides stiffness
`and yet also has a thin Wall, so as to not add appreciably to
`the overall diameter. In the embodiment of FIG. 4, stiffening
`cannula 50 is provided With spiral shaped grooves 52.
`Grooves 52 may be cut into or otherWise formed at the distal
`end of stiffening cannula 50 to increase the ?exibility of the
`distal end of the stiffening cannula.
`
`[0036] FIG. 5 shoWs a vieW of the embodiment of FIG. 4
`When a bending force is applied at the distal end of apparatus
`10. Such forces are typically encountered When the appara
`tus negotiates a bend in the vasculature. As shoWn in the
`?gure, When the tip is exposed to a bending force, a smooth
`bending transition results betWeen the distal end 14 of
`catheter 12, the soft polymer tip 24 of inner cannula 20, and
`the stiffening cannula 50. The spiral-shaped grooves 52 of
`stiffening cannula 50 in effect convert the distal portion of
`cannula 50 into a helical spring. As a result, the distal tip
`portion of the apparatus becomes substantially kink resis
`tant, and bends as shoWn in FIG. 5.
`
`[0037] For purposes of comparison, FIG. 6 is a longitu
`dinal cross-sectional vieW of a prior art apparatus 110. Prior
`art apparatus 110 is similar in certain respects to the inven
`tive apparatus, as it includes a catheter 112, an inner cannula
`120 and a stiffening cannula 150. Catheter 112 includes
`distal end 114, and inner cannula 120 includes distal end
`124. Stiffening cannula 150, hoWever, does not include any
`grooves or other structure that imparts increased distal
`?exibility. The prior art apparatus 110 is shoWn in FIG. 6
`exposed to a distal bending force. Since this prior art
`apparatus does not include a distal portion of increasing
`?exibility as is present in the embodiment of FIG. 5, the
`application of the bending force creates an abrupt stiffness
`change at the distal tip from the stiff distal end of the
`stiffening cannula 150 to the soft distal tip 124 of the inner
`cannula 120. Such an abrupt change in stiffness may result
`in the formation of a bump or other restriction 125 at the
`
`joint betWeen the rigid cannula body and the soft tip 124 of
`the inner cannula. Further, the soft cannula tip is prone to
`kinking and/or breaking off.
`[0038] The spiral cut shoWn in FIGS. 4 and 5 includes
`similarly siZed and spaced coil turns. Alternatively, hoWever,
`the stiffening cannula can be formed to have coil turns
`spaced an increasing distance from each other, that is, at a
`greater pitch, as the cannula approaches the distal tip, to
`further increase the ?exibility at the distal tip. As another
`alternative, the Width and/or thickness of the material form
`ing the separate coil turns can be decreased in sequential
`fashion toWard the distal end of the apparatus, in order to
`still further decrease the ?exibility toWard the distal end of
`the device. The spiral shaped grooves can be formed in the
`distal portion of stiffening cannula 50 by any means Well
`knoWn in the art, such as by laser cutting the grooves into the
`cannula.
`[0039] Although the embodiment of FIGS. 4 and 5 uti
`liZes spiral cut slots to provide the portion of increased
`?exibility, other knoWn mechanisms for providing a transi
`tion from a stiff portion to a more ?exible portion may be
`substituted for the spiral cut slots. For example, a taper can
`be ground on the distal end of the stiffening cannula. The
`taper reduces the thickness of the cannula Wall, thereby
`imparting additional ?exibility at the reduced thickness
`portion. Alternatively, one or more short distal segments of
`increasing ?exibility (in the distal direction) can be adhered
`to the distal end of a stiffening cannula by conventional
`means, such as heat or glue bonding, to increase distal
`?exibility. The distal tip of the stiffener can also be made
`?exible by adhering a Wire coil to the inner surface of a
`stiffening cannula.
`[0040] Alternatively, increased distal ?exibility could also
`be attained by cutting a series of parallel slots, either
`transversely or longitudinally, along the distal portion of the
`stiffening cannula. The slots could go, for example, from
`about halfWay through the diameter up to about 90% of the
`Way through the diameter of the cannula. If desired, some
`slots can also be made fully through the Wall, as long as the
`structural integrity of the cannula is retained. As yet another
`alternative, the slots can all be made on one side or at one
`portion of the cannula, thereby only alloWing ?exing in one
`plane or at the one cannula portion. Those of ordinary skill
`in the art can readily determine other suitable ?exibility
`transition methods Without undue experimentation, all of
`Which are considered Within the general teachings of the
`present invention.
`[0041] Another embodiment of the present invention is
`shoWn in FIG. 7. In this embodiment, an inner sleeve 60 is
`added interiorly of stiffening cannula 50. The distal end of
`inner sleeve 60 extends past the distal end of stiffening
`cannula 50. The distal end 62 of the inner sleeve may extend
`all the Way to the distal end of inner cannula 20, or
`alternatively, may be betWeen the respective distal ends of
`the inner cannula and the stiffening cannula. In either event,
`the distal end of the inner sleeve may be considered to
`extend substantially to the distal end of the inner cannula.
`The presence of the inner sleeve eliminates sharp edges that
`may be produced by the stiffening cannula. The inner sleeve
`also adds strength to the distal tip of the apparatus, thereby
`reducing the possibility of kinking and/or breakage at the tip,
`and reducing the abrupt change in stiffness of the prior art
`design.
`
`

`
`Page 9 of 10
`
`US 2005/0004523 A1
`
`Jan. 6, 2005
`
`[0042] In the embodiment of FIG. 7, it is not necessary to
`incorporate a spiral slot or other ?exibility-enhancing fea
`ture to stiffening cannula 50. Inner sleeve 60 can be formed
`to have a loWer coef?cient of friction than the stiffening
`cannula, thereby facilitating passage of the Wire guide
`through the inner lumen. If desired, inner sleeve 60 and
`stiffening cannula 50 can be bonded together to form a
`unitary piece.
`[0043] In yet another alternative embodiment, inner sleeve
`60 can be provided in conjunction With a spiral cut or
`otherWise transitioned stiffening cannula 50. If desired, inner
`sleeve 60 and inner cannula 20 can be formed to embed the
`spiral cut stiffening cannula. Inner sleeve 60 can also be used
`to tailor the ?exibility of a spiral cut cannula, and to
`eliminate any sharp edges produced by a spiral cut cannula.
`As described herein, inner sleeve 60 can be formed from
`conventional biocompatible materials suitable for such a
`purpose, such as PTFE, nylon, or any other similar materi
`als.
`
`[0044] Those skilled in the art Will appreciate that the siZes
`provided herein are examples only, and components of other
`siZes are also Within the scope of the invention. When the
`apparatus of the present invention is used for catheteriZation,
`a small diameter needle, such as an 18 gauge needle, having
`a correspondingly short bevel tip, can be used for initial
`entry into the vessel. A small diameter Wire guide, such as
`a 0.018 inch (0.46 mm) O.D. Wire guide, can then be inserted
`through the bore of the needle, and the needle can be
`WithdraWn. The inventive apparatus can then be slid over the
`small diameter Wire guide and into the vessel. The smooth
`transition provided by the inventive apparatus betWeen the
`Wire guide and the larger diameter catheter (e.g., 0.039 inch
`0D. or greater) minimiZes trauma to the patient that might
`otherWise occur in the absence of such a transition. The Wire
`guide, inner cannula and stiffening cannula can then be
`removed, leaving the large diameter cannula in the vessel
`opening. If desired, a large diameter (e.g., 0.035 or 0.038
`inch O.D.) Wire guide may be inserted through the lumen of
`the catheter, and an appropriately-sized medical device, such
`as a diagn