US20060282016A1 - Guide wire with hydrophilically coated tip - Google Patents

Abstract

A guide wire including a lubricous distal portion and a less lubricous intermediate portion proximal of said distal portion. One guide wire provides a highly lubricous distal portion with a hydrophilic layer and a less lubricous intermediate portion with a hydrophobic layer. Another guide wire provides a lubricous distal portion with a polymer tip that is itself hydrophilic. Yet another guide wire provides a less lubricous intermediate portion using a stainless steel coil helically wound around the tapering intermediate portion. The coil is preferably coated with a hydrophobic coating such as PTFE or silicone. The coil can either abut the distal portion proximal end or extend into the distal portion interior.

Description

• This is a continuation of U.S. patent application Ser. No. 10/680,447 filed on Oct. 7, 2003 which is a continuation of U.S. patent application Ser. No. 09/874,794 filed on Jun. 5, 2001, now U.S. Pat. No. 6,656,134 which is a continuation of application Ser. No. 09/361,881 filed on Jul. 27, 1999, now U.S. Pat. No. 6,251,086 which is a continuation of application Ser. No. 08/812,750 filed on Mar. 6, 1997, now U.S. Pat. No. 5,924,998.
FIELD OF THE INVENTION
• The present invention relates generally to intravascular guide wires. In particular, the present invention relates to guide wires having a lubricous hydrophilic tip and a less lubricous intermediate portion proximal the distal tip.
BACKGROUND OF THE INVENTION
• Guide wires are used in various procedures within various conduits in the body. In particular, they are used in Percutaneous Transluminal Coronary Angioplasty (PCTA) and other coronary procedures. This can involve inserting a guide wire through an incision in the femoral artery near the groin, advancing the guide wire over the aortic arch, into a coronary artery, and across a lesion to be treated. Guide wires can be inserted directly into the vasculature or within a guide catheter. The distal end of the guide wire ultimately lies directly within the vasculature.
• Guide wires serve to guide devices into position for both therapeutic and diagnostic purposes. For this to happen, the guide wire itself must be properly positioned. This is difficult, as it involves moving a wire tip through a narrow opening within a narrow vessel, from 180 centimeters away. This task can be especially difficult as the guide wire must be extremely flexible at the distal end to enable the guide wire tip to enter vessel branches at various angles. The extreme flexibility can come at the expense of axial or rotational strength. Improved responsiveness to remotely applied forces, both rotational and axial, has been provided by reducing friction along the guide wire length. In particular, providing a highly lubricous guide wire distal region of about 12 inches has proven advantageous in maneuvering guide wires through the arteries to reach the site of blockage. Having this same lubricous coating on the tip of the wire has been advantageous in making the wire perform better in finding small openings in the blockages and crossing them.
• Once the guide wire tip is in position, devices including catheters are advanced into position over the guide wire and withdrawn over the guide wire. Such catheter movement acts upon, and tends to move, the guide wire contained within. This can tend to dislodge the guide wire tip. Minor patient movement including breathing also acts to move the guide wire as does handling of the guide wire proximal portion extending from the patient. Dislodging the guide wire tip may require repositioning the guide wire, with the attendant time and effort. Once in position, therefore, stability and resistance to applied forces is preferred over the initially desirable ease of movement and responsiveness to applied forces.
• What is desirable and has not been provided is a guide wire easily maneuvered into position across a tight lesion, yet providing stability and resistance to movement once the guide wire is in position.
SUMMARY OF THE INVENTION
• The present invention provides a guide wire having a highly lubricous distal portion, followed proximally by a less lubricous intermediate portion, followed proximally by a proximal portion. The guide wire includes a core member within, preferably formed of metal and having a proximal constant cross section portion, followed distally by a tapered portion, followed distally by a reduced cross section portion. The tapered portion can have multiple tapers. The distal end of the reduced cross section portion is preferably flattened into a ribbon, providing greater flexure in one plane. A preferred core has a circular cross section in the proximal and tapered portions. One guide wire embodiment has a intermediate and distal portion length totalling about 12 to 14 inches. A preferred length for the distal portion is about 1 to 3 centimeters.
• A preferred guide wire achieves a lubricous distal portion by having a hydrophilic surface in the distal portion. A less lubricous intermediate portion is achieved by having a hydrophobic surface in the intermediate portion. The hydrophilic surface has a very low coefficient of friction when placed against an artery wall in a blood filled artery. The hydrophobic surface has a higher coefficient of friction against the artery wall.
• The present invention distal portion can be formed of a polymer not necessarily hydrophilic, but having a hydrophilic coating thereover. The intermediate portion can be formed of a hydrophobic polymer sleeve over the core wire or a polymer sleeve over the core wire having a hydrophobic coating. In another embodiment, the intermediate portion can include a coil around the core wire, the coil preferably having a hydrophobic coating. The coil wire abuts the distal portion in one embodiment, and is embedded beneath the distal polymer in another embodiment. In yet another embodiment, the distal portion includes a distal tip having a proximally tapered proximal portion, and the coil wire distal end contacts the distal tip in the tapered portion, thereby centering the coil.
• The present invention provides the ability to cross tight lesions by having a highly lubricous, low friction, distal portion, which is relatively easy to slide through a narrowed vessel region. The extremely lubricous portion is limited to a shorter length relative to previous devices. A preferred length is about 1 inch. The lubricity is limited to the portion where the extreme lubricity is most needed, the distal portion. Lower friction is required in the extreme distal portion because the core member there is narrower and therefore weaker, not having the strength of the more proximal portion to handle being axially pushed from the proximal end against obstructions. Low friction is also required in this portion because this is the portion that is required to initially cross an extremely tight lesion, something not required of the more proximal portion. The low friction facilitates the wire tip first piloting into the small remaining opening in the lesion and then crossing the lesion without buckling the wire.
• To counteract the highly lubricous, low friction distal portion, the present invention deliberately provides a less lubricous, higher friction intermediate portion, proximal of the distal portion. The intermediate portion can lie against an artery wall, or guide catheter wall, “anchoring” the guide wire. The present invention, by having an anchoring portion proximal of the distal portion, provides resistance to forces such as catheter movement over the guide wire, which could act to dislodge the guide wire tip from its desired position.
• While the anchoring portion friction will not prevent all movement of the guide wire, it provides sufficient static friction to resist unintentional movement due to either catheter movement or patient movement. In this way, a series of minor forces acting on the guide wire proximal portion, if below the threshold of static friction presented by the anchoring portion, will not be translated into a series of minor movements of the guide wire distal tip.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a fragmentary, side cross-sectional view of a guide wire, in accordance with the present invention, having a coil in the intermediate portion;
• FIG. 2 is a fragmentary, side cross-sectional view of a second embodiment of a guide wire having a core wire shown in phantom;
• FIG. 3 is a fragmentary, side cross-sectional view of a third embodiment of a guide wire having a coil extending into the distal tip;
• FIG. 4 is a fragmentary, side cross-sectional view of a fourth embodiment of a guide wire having a two part coil extending into the distal tip; and
• FIG. 5 is a fragmentary side cross-sectional view of a fifth embodiment of a guide wire having a proximally tapered polymer tip and a coil sitting on the taper.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• FIG. 1 illustrates a fragmentary, side cross-sectional view of a guide wire20 having adistal portion22, anintermediate portion24, and aproximal portion26. Guide wire20 has a surface extending the length thereof, as indicated at21. The length ofdistal portion22 is indicated byarrows40 and the length ofintermediate portion24 byarrows44. Guide wire20 includes anelongate core member28 having a constantcross section portion30, a taperedportion32 and a reducedcross section portion34.Core member28 preferably has a circular cross section inportions30 and32. The intermediate taperedportion32 may comprise a single taper or a series of tapers with regions of constant diameter in between.Core28 is preferably formed from high tensile strength stainless steel wire or a super-elastic alloy such as Nitinol.
• Core reducedcross section portion34, illustrated lying within adistal portion22, provides extreme flexibility to the guide wire where needed, at the extreme distal end. Reducedcross section portion34 is preferably flatter in one dimension than another, forming a ribbon, providing more flexibility in one dimension than another. Tip flexibility is desirable for insinuating the guide wire into ever more distal and tortuous coronary arteries. The embodiment ofdistal portion22 illustrated can include adistal tip38 encasing core reducedcross section portion34. In a preferred embodiment,distal tip38 includes a polymeric material.Distal tip38 is preferably radiopaque to allow for tracking the tip position using fluoroscopy. In one embodiment,tip38 includes polyurethane and is loaded with tungsten, 85 to 90 percent by weight, for radiopacity. In one embodiment, a polyurethane sleeve formsdistal tip38, which can be between about ½ and 7 centimeters in length. In a preferred embodiment,tip38 is between 1 and 3 centimeters in length.
• Distal portion22 according to the present invention is lubricous. In a preferred embodiment,distal portion22 is extremely lubricous. In one embodiment, the lubricity is provided by having a hydrophilic material at the surface ofdistal portion22. A hydrophilic surface makes the surface highly lubricous when in contact with a water based fluid such as blood. In the embodiment illustrated inFIG. 1, lubricity is provided by adistal layer36 over reduceddiameter portion34 anddistal tip38. A hydrophilic coating over the guide wire presents very little friction when sliding through the artery interior. This provides ease of crossing tight lesions, allowing difficult and distally remote lesions to be treated. In one embodiment,distal layer38 includes a polyvinylpyrrolidone (PVP) coating. In another embodiment,distal layer38 includes a polyethyl maleic anhydride coating. In a preferred embodiment,distal portion22 is about 0.014 inches in diameter.
• Proximal ofdistal portion22 isintermediate portion24 which has a lubricity less than that ofdistal portion22. In a preferred embodiment,intermediate portion24 haslength44 of about 20 to about 30 centimeters. In one embodiment,intermediate portion24 is about 28 centimeters long and about 0.0130 to 0.0135 inches in diameter. Guide wires used to deliver stiffer devices may have a shorter intermediate region to make the wire more supportive. In these casesintermediate portion24 may be as short as 3 centimeters. In the embodiment depicted inFIG. 1,intermediate portion24 includes taperedcore portion32 which is encased in acoil42. A preferred coil is formed of stainless steel and coated with hydrophobic coating. A preferred hydrophobic coating is PTFE or silicone.Coil42, by presenting a series of wires oriented transversely to the axial direction of guide wire movement, provides resistance to axial movement. The coil also provides increased pushability and kink resistance for taperedcore portion32. In compression, the coil provides axial strength over the length of taperedcore portion32 which decreases in strength with decreasing core cross section. The distal end ofcoil42 can be attached tocore28 using solder or adhesive. The proximal end ofcoil28 is preferably secured tocore28 by adhesive.
• Intermediate portion24 provides a higher friction anchoring portion to maintain the position ofdistal portion22. If too much of the guide wire is extremely lubricous, the distal tip can be difficult to fix exactly in position, as catheter advancement and retraction over the guide wire can apply forces to the guide wire, tending to move the guide wire tip. Patient movement, including breathing, can also translate into movement at the guide wire distal tip. By providing an intermediate region having a less lubricous surface, an intermediate anchoring region is provided, which presents friction against the vessel wall, presenting resistance to forces that would otherwise be translated into movement at the distal tip. While the intermediate anchoring portion cannot resist all forces applied to the guide wire and prevent all tip movement, the static friction of the anchored guide wire intermediate portion does provide a threshold barrier to lower level forces. Thus, a series of small forces is not necessarily translated into a series of low level movements of the guide wire tip.
• Proximal portion26 in a preferred embodiment, extends to the guide wire proximal end. Included in proximal portion inFIG. 1 is constant crosssection core portion30. In a preferred embodiment,proximal portion26 includes a stainless steel wire about 0.013 inches in diameter and has a polytetrafluoroethylene (PTFE) coating. In one embodiment,proximal portion26 is less lubricous thanintermediate portion24. In another embodiment,proximal portion26 is more lubricous thanintermediate portion24 but less lubricous thandistal portion22.
• FIG. 2 illustrates another embodiment of the invention,guide wire120, having aproximal portion126, anintermediate portion124, and adistal portion122.Distal portion122 is preferably about ½ to 7 centimeters in length, andintermediate portion124 can be 1 to 15 inches in length and is preferably about 8 to 12 inches in length. Withinguide wire120 is a core128 having aconstant diameter portion130, a taperedportion132 and a reduceddiameter portion134.Core128 can be substantially similar tocore28 discussed with respect toFIG. 1.Guide wire120 has a lubricousdistal portion122 and a less lubricousintermediate portion124. In the embodiment depicted inFIG. 2,distal portion122 includes adistal tip136.Distal tip136 can be similar todistal tip36 inFIG. 1. In some embodiments,distal tip136 is formed of polyurethane, and coated with hydrophilic coatings as discussed above with respect toFIG. 1.Distal tip136 is preferably radiopaque to allow for tracking the tip position using fluoroscopy. In one embodiment,tip136 includes polyurethane and is loaded with tungsten, 85 to 90 percent by weight, for radiopacity.Distal tip136 is preferably more radiopaque thanintermediate portion124.
• Intermediate portion124 provides a less lubricous portion proximal to lubricousdistal portion122, as in the embodiment ofFIG. 1, but without requiring a coil. The lower lubricity is provided by having a hydrophobic surface. This can be provided with both hydrophobic sleeves and hydrophobic coatings over sleeves that are not necessarily hydrophobic.Sleeve142, illustrated encasing taperedcore portion132, can be formed of a hydrophobic polymer. Hydrophobic polymers include fluorinatedethylenepropylene (FEP) and polytetrafluoroethylene (PTFE).Intermediate portion124 can also be formed of a material such as polyether block amide (PEBAX) or polyethylene coated with a low friction, hydrophobic coating such as silicone, paralene, PTFE, or FEP.Guide wire120 can be formed bysleeving tube142 overcore128, bonding the tube in place at its proximal end with adhesive, shrinking a suitable distal tip material over reduceddiameter core portion134, and bonding the distal portion ofsleeve142 to the proximal portion of the distal tip. Another suitable method includes heat shrinking a polymeric tube overcore128, grinding the tube to an approximate diameter of about 0.0130 to 0.0135 inches, then selectively coatingintermediate portion124 and possiblydistal portion122 also, with one of the hydrophobic coatings, and then coatingdistal portion122 with one of the previously described hydrophilic coatings.
• FIG. 3 illustrates yet another embodiment of the invention, aguide wire220, havingproximal portion226 followed distally byintermediate portion224 followed distally bydistal portion222. A core228 proceeds distally from aconstant diameter portion230 to a taperedportion232 to a reduceddiameter portion234.Intermediate portion224 includes acoil242 surrounding the tapered portion of the core, withcoil242 proceeding distally from aconstant diameter portion241 to a taperedportion243 to a reduceddiameter portion244.Core228 is preferably flattened into a ribbon shape in reduceddiameter portion244. Reduceddiameter portion244 is embedded withindistal tip238 when the polymer tip is shrunk onto the wire. In this embodiment, neither solder nor adhesive are required to secure the distal end ofcoil242 tocore228. The proximal end ofcoil242 can be secured tocore228 by soldering.Distal tip238 can be coated with ahydrophilic layer236 as discussed above with respect to the embodiment ofFIG. 1. The materials ofdistal tip238 andlayer236 can be similar to those ofdistal tip38 andlayer36.
• FIG. 4 illustrates yet another embodiment of the invention, aguide wire320, having aproximal portion326, followed by anintermediate portion324, followed distally by adistal portion322. A core328 proceeds distally from aconstant diameter portion330 to a taperedportion332, to a reduceddiameter portion334. Acoil342 surroundscore328 over the intermediate and distal portions. In the embodiment shown,coil342 is formed of aproximal coil323 and adistal coil325 soldered together at340.Proximal coil323 is preferably formed from a less radiopaque material such as stainless steel. This coil can be coated with a hydrophobic coating such as PTFE.Distal coil325 is preferably formed of a more radiopaque material such as platinum. Combinedcoil342 is attached tocore328 proximally with solder at341 and distally with either solder or welding at338. Ahydrophilic coating336 is applied to the distal portion ofdistal coil325 in one embodiment by first applying a Tie layer polymer such as polyurethane by dip or spray coating, followed by applying a hydrophilic coating over the Tie layer coating. The hydrophilic coating can be one of the coatings described previously with respect to guide wire20 inFIG. 1.
• FIG. 5 illustrates yet another embodiment of the invention, aguide wire420 having aproximal portion426, followed by anintermediate portion424, followed distally by adistal portion422. A core428 proceeds distally from acontact diameter portion430 to a taperedportion432, to a reduceddiameter portion434. Adistal tip436, preferably formed of a polymeric substance, surrounds core reduced diameterdistal portion434.Distal tip436 includes a taperedportion437, which tapers proximally toward core taperedportion432.Guide wire420 includes acoil442 which extends distally over core taperedportion432.Coil442 has adistal end443 which contacts and terminates within distal tip taperedportion437.Coil442 is thus always centered oncore428, as transverse movement of coildistal end443 is opposed by distal tip taperedportion437.Tip436 can be heated to embedend443 therein.
• While use of the present invention can be described with reference to any of the embodiments, the embodiment ofFIG. 1 is selected for further illustration. In use, core reduceddiameter portion34 can be bent by the treating physician, prior to insertion into the patient. Having a bent distal tip allows orienting the tip for insertion into arteries by rotating the proximal end of the guide wire, which rotates the bent distal tip toward arterial side branches. The guide wire can be advanced through a guide catheter or directly through the vasculature. After having advanced the guide wire into a coronary artery such as the left coronary artery, the guide wire is maneuvered into selected smaller arteries. In attempting to insinuate the distal most portion of the guide wire into smaller arteries, the lubricous tip provides easier initial advancement into the artery. When a lesion is to be crossed, lubricousdistal portion22 provides low resistance to axial movement into and through a narrow passage. Low resistance is advantageous as there is less tendency for core reduceddiameter portion34 to kink or buckle when pushed by the treating physician from the extreme proximal end.
• Oncedistal portion22 is across the lesion, it is highly preferred that the guide wire tip position not change, despite minor changes in proximal handling of the guide wire, movement of other devices over the guide wire, patient breathing, blood flow, and minor changes in frictional conditions along the guide wire length. The present invention allows a guide wire to resist these forces by havingintermediate portion24 lie against and be “anchored” to the vessel or guide catheter wall, presenting a higher quantity of static friction that must be overcome to dislodge the guide wire distal tip, than presented with wires having longer lubricous distal surfaces. The present invention thus makes it less likely that the guide wire will move inside the artery unless the physician is directly intending to move it.
• The combination of lubricous distal portion and less lubricous intermediate portion thus serves to promote ease of distal tip advancement across tight lesions while stabilizing the distal tip position once placed, allowing other devices to be accurately guided into position by the guide wire.
• Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The inventions's scope is, of course, defined in the language in which the appended claims are expressed.

Claims (1)

1. A guide wire having a distal end and a proximal end comprising:

an elongate core;

a lubricous distal portion;

an intermediate portion, proximal of said distal portion, said intermediate portion being less lubricous than said distal portion; and

a proximal portion proximal of said intermediate portion.

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