Patent Publication Number: US-7914493-B2

Title: Wire guide with engaging portion

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application claims the benefit under 35 U.S.C. §119(e) of U.S. provisional patent application Ser. No. 60/741,626, filed Dec. 2, 2005 and entitled WIRE GUIDE WITH EXTENDABLE CORE WIRE, and of U.S. provisional patent application Ser. No. 60/790,117, filed Apr. 7, 2006 and entitled WIRE GUIDE WITH ENGAGING PORTION, the entire contents of each of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to wire guides used in diagnostic and interventional medical procedures. More specifically, this invention relates to wire guides used for access to complex distal anatomy for diagnostic and interventional procedures. 
     2. Related Technology 
     Wire guides (also known as guide wires) have been used in percutaneous entry procedures for diagnostic X-Ray studies and interventional procedures since about the 1950&#39;s when the idea of percutaneous, wire guided entry into the vasculature was conceived. As shown in  FIGS. 18   a  and  18   b , a wire guide U known in the prior art is typically inserted percutaneously into a body vessel V and advanced or manipulated within the body vessel V until reaching a desired location W. A catheter X (or other insertable device) is then positioned over the wire guide U, inserted percutaneously into the body vessel V, and advanced along the wire guide U to a desired location to perform a desired treatment, diagnosis, investigation, or medical intervention. 
     Therefore, wire guides typically have particular characteristics to improve the pushability of the wire guide U within the body vessel V. For example, the wire guide U is preferably generally radially flexible to negotiate the potentially-winding path of the body vessel V and to reduce potential damage to the body vessel walls while the wire guide U is being advanced. More specifically, wire guides U typically include a distal tip Y that is generally radially flexible. As another example, the wire guide shaft Z preferably has a relatively high axial stiffness to improve the pushability and control of the wire guide U along the body vessel V. The relatively high axial stiffness reduces kinking and bending so that the wire guide U will not become stuck or obstructed during the advancement thereof along the body vessel V. The axial stiffness of the wire guide shaft Z is preferably sufficient to prevent the wire guide U from folding over itself and becoming obstructed within the body vessel V when the distal tip Y encounters a bend in the body vessel V. 
     However, after being positioned as desired in the body vessel V, currently known wire guides may become tangled or obstructed during the advancement of the catheter X over the wire guide U. For example, the advancing catheter X may encounter a slightly curved portion of the wire guide U and undesirably exaggerate the curve of the wire guide U. More specifically, the curved wire portion may bend around the rim of the catheter X and bend the wire guide U into S-shaped curve Z, thereby resisting or preventing advancement of the catheter X. 
     It may be undesirable or difficult to improve the advanceability of the catheter along the wire guide by increasing the diameter or the axial stiffness of the wire guide because such a design change may decrease the pushability of the wire guide within the body vessel. For example, a wire guide with increased axial stiffness may not have enough radial flexibility to negotiate the winding path of the body vessel or may damage the body vessel while doing so. As another example, an increased-diameter wire guide may not be small enough to be received by the catheter or may be undesirably invasive to the body vessel. 
     Another disadvantage to the current design is that it may be difficult for the physician to keep the distal end of the wire guide properly positioned at the target site. For example, once the physician positions the wire guide at the desired location, the wire guide may migrate to another position within the body vessel. More specifically, the advancing catheter may bend the wire guide and cause the distal end of the wire guide to move from its desired position, as discussed above. 
     It is therefore desirous to provide a wire guide with a relatively small diameter that is able to be effectively pushed into a desired position, that is able to be received by a catheter, that is able to permit advancement of a catheter there along, and that is able to maintain its position at a desired location. 
     SUMMARY 
     In overcoming the limitations and drawbacks of the prior art, one aspect of the present invention provides a wire guide for percutaneous guidance within a body vessel. The wire guide includes an outer component for insertion into the body vessel and a core wire disposed in the outer component and movable between first and second positions. The core wire includes an engaging portion that extends from the outer component to engage the body vessel when the core wire is in the second position. 
     In one aspect of the invention, the engaging portion is an anchoring portion for extending into a wall of the body vessel and anchoring the wire guide thereto when the core wire is in the second position. The engaging portion may also be a drug delivery portion for delivering a drug to the body vessel. The drug delivery portion may be located at a distal tip of the core wire, or it may be proximal of the distal tip. 
     In another aspect of the present invention, the outer component is a coiled wire. More particularly, the outer component may be defined by a multiple filament, helically wound row of wires. When in the second position, the core wire extends between adjacent coils of the coiled wire. Alternatively, the core wire extends from a distal tip of the outer component when in the second position. 
     The engaging portion may be a tapered tine, a spiral-shaped portion, a barb portion, or any other suitable shaped portion. The core wire may also include a second engaging portion extending from the outer component when the core wire is in the second position. The engaging portion may be completely within the outer component when the core wire is in the first position. 
     In yet another aspect of the present invention, a wire guide is provided for guidance within a body vessel, the wire guide including a distal portion, a proximal portion, and a body portion. The distal portion includes an end portion for insertion into a wall of the body vessel and a stop portion having an effective diameter substantially greater than that of the end portion so as to resist insertion of the end portion into the wall beyond a maximum insertion distance. 
     In one design, the stop portion is a protrusion extending from the distal portion of the wire guide in a direction generally perpendicular a longitudinal axis of the wire guide. The stop portion is preferably more flexible when urged towards the distal end than when urged towards the proximal end. In another design, the stop portion is a loop portion having first and second ends attached to the wire guide. 
     During the initial percutaneous delivery of the wire guide to the body vessel, a sheath may be disposed over the distal portion to radially constrain the stop portion and facilitate delivery of the wire guide. 
     In another aspect of the present invention, a method of engaging a wire guide with a body vessel is provided, including the steps of: inserting the wire guide into the body vessel, extending an engaging portion of the wire guide into an engaging position, and engaging the body vessel with the engaging portion to anchor the wire guide thereto. 
     The method may also include the step of applying a desired force to the wire guide in a direction extending away from the body vessel. The method may also include the step of advancing a catheter along the wire guide and into the body vessel. 
     In yet another aspect of the present invention, an assembly for insertion within a body vessel is provided, including a wire guide and a catheter having a receiving portion configured to receive the wire guide and to be advanced there along into the body vessel. 
     The present invention may be used in a blood vessel for various procedures, such as the treatment of stenotic lesions. Alternatively, the present invention may be used in a nonvascular system, such as the urinary tract or the biliary system, for the advancement of medical instruments, such as a laparoscope. 
     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a wire guide embodying the principles of the present invention and being used for percutaneous guidance within a body vessel; 
         FIG. 2   a  is an enlarged cross-sectional view of the wire guide shown in  FIG. 1 , where the core wire of the wire guide is in a retracted position; 
         FIG. 2   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 2   a , with the core wire in an extended position; 
         FIG. 3  is a environmental view of the wire guide from  FIG. 1  being inserted into a body vessel, where the core wire is in the retracted position; 
         FIG. 4  is an environmental view of the wire guide from  FIG. 3  engaging the body vessel, where the core wire is in the extended position; 
         FIG. 5   a  is an environmental view of the wire guide from  FIG. 4 , where the core wire extends into the body vessel wall and the catheter is being advanced along the wire guide; 
         FIG. 5   b  is an environmental view of the wire guide from  FIG. 4 , where the core wire extends through the body vessel wall and the catheter is being advanced along the wire guide; 
         FIG. 6   a  is an enlarged cross-sectional view of a wire guide having an alternative design embodying the principles of the present invention, with the core wire in a retracted position; 
         FIG. 6   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 6   a , with the core wire in an extended position; 
         FIG. 7   a  is an enlarged cross-sectional view of a wire guide having another alternative design embodying the principles of the present invention, with the core wire in a retracted position; 
         FIG. 7   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 7   a , with the core wire in an extended position; 
         FIG. 8   a  is an enlarged cross-sectional view of a wire guide having yet another alternative design embodying the principles of the present invention, with the core wire in a retracted position; 
         FIG. 8   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 8   a , with the core wire in an extended position; 
         FIG. 9   a  is an enlarged cross-sectional view of a wire guide having yet another alternative design embodying the principles of the present invention, with the core wire in a retracted position; 
         FIG. 9   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 9   a , with the core wire in an extended position; 
         FIG. 10   a  is an enlarged cross-sectional view of a wire guide having another alternative design embodying the principles of the present invention, with the core wire in a retracted position; 
         FIG. 10   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 10   a , with the core wire in an extended position; 
         FIG. 11   a  is an enlarged cross-sectional view of a wire guide having yet another alternative design embodying the principles of the present invention, with the core wire in a retracted position; 
         FIG. 11   b  is an enlarged cross-sectional view of the wire guide shown in  FIG. 11   a , with the core wire in an extended position; 
         FIG. 12  is a side view of a distal portion of a wire guide having another alternative design embodying the principles of the present invention, where a stop portion prevents over-insertion of the wire guide into a body vessel wall; 
         FIG. 13  is an environmental view of the wire guide shown in  FIG. 12  being inserted into a body vessel wall; 
         FIG. 14  is a side view the wire guide shown in  FIG. 12  with a sheath disposed over the distal portion to radially constrain the stop portion; 
         FIG. 15  is a side view of a distal portion of a wire guide having another alternative design embodying the principles of the present invention; 
         FIG. 16  is a side view of a distal portion of a wire guide having another alternative design embodying the principles of the present invention; 
         FIG. 17  is a side view of a distal portion of a wire guide having another alternative design embodying the principles of the present invention, where the stop portion includes a loop portion; 
         FIG. 18   a  is an environmental view of a wire guide known in the prior art being inserted into a body vessel; and 
         FIG. 18   b  is an environmental view of the wire guide shown in  FIG. 18   a  having a catheter being advanced there along. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings,  FIG. 1  shows a wire guide  10  for percutaneous insertion within a body vessel. The wire guide  10  includes a proximal end  12  for controlling and advancing the wire guide  10 , a distal end  14  for engaging and disengaging inner surfaces of the body vessel, and a body portion  16  extending between the proximal and distal ends  12 ,  14 . The body portion  16  and the distal end  14  cooperate to define an effective length  24 , which is generally defined as the length of the wire guide  10  that is able to be inserted into the body vessel. The distal end  14  is preferably generally tapered and the body portion  16  has a generally constant diameter  26  to improve the ease of insertion into the body vessel. Despite being generally radially flexible, the wire guide  10  extends generally linearly along a longitudinal axis  28  when in a relaxed state  30 . 
     As shown in  FIGS. 1 and 2   a , the wire guide  10  generally includes: an outer component  18  defining the outer surface of the wire guide  10 ; a core wire  20  moveably received within the outer component  18  between a retracted position  36  and an extended position  38 ; and an actuator  40  for controlling the movement of the core wire  20 . The core wire  20  includes an engaging portion that selectively engages a wall of the body vessel when the core wire  20  is in the extended position  38 . For example, in  FIGS. 2   a  and  2   b , the engaging portion is an anchoring portion  42  configured to extend into the body vessel wall and anchor the wire guide  10  thereto. 
     The outer component  18 , preferably defined by a coiled wire  44 , defines a conduit  46  for receiving the core wire  20 . For example, the coiled wire  44  is a tightly wound helical coil having an axial stiffness and a radial flexibility that are conducive to navigation of tortuous pathways of the body vessel. The wire guide  10  preferably increases in radial stiffness from the distal end  14  towards the proximal end  12 . Additionally, the wire guide  10  may be made of any suitable material or combination of materials that are biocompatible or capable of being made biocompatible, such as stainless steel, other biologically compatible metals, polymers, plastics, alloys (including super-elastic alloys), or composite materials. In one example, the distal end  14  and the body portion  16  intermediate section  44  comprise a nickel-titanium alloy (commonly known as “nitinol,” an acronym of Nickel Titanium Naval Ordnance Laboratory, where the alloy&#39;s properties were discovered). Nitinol is an alloy containing nearly equal numbers of nickel and titanium atoms, and the relative amounts of nickel and titanium can be varied by a few percent. 
     The outer component  18  shown in  FIG. 2   a  has a single coiled wire wound at a pitch angle  48  suitable for a desired flexibility. A relatively steep pitch angle  48 , where a steep pitch angle  48  is defined as being generally close to 90 degrees, is typically more flexible than a generally shallow pitch angle. The pitch angle  48  of the coiled wire  44  may vary along the length of the wire guide  10  to affect the radial stiffness thereof. For example, the pitch angle  48  is typically steeper at the distal end  14  of the wire guide  10  where radial flexibility is generally desirable. 
     An end cap  50  cooperates with the coiled wire  44  to define the conduit  46  and the distal end  14  of the wire guide  10  in  FIGS. 2   a  and  2   b . More specifically, the end cap  50  is located at a distal tip  51  of the wire guide  10  and defines an aperture  52  generally aligned with the wire guide longitudinal axis  28  so that the anchoring portion  42  extends through the aperture  52  when the core wire  20  is in the extended position  38 . The diameter of the aperture  52  is preferably smaller than the inner diameter of the coiled wire  44  to provide a controlled delivery of the anchoring portion  42  from the end cap  50  while providing an increased radial flexibility of the body portion  16  of the wire guide  10 . The end cap  50  may be connected to the coiled wire  44  by any suitable method, such as welding, or connecting the components via an adhesive or a fastener. Alternatively, the end cap and the coiled wire are a single, unitary component. For example, the end cap in this alternative design is the distal coil of the coiled wire. The end cap  50  may be made of a radiopaque material that is visible within a patient&#39;s body via a fluoroscope or a magnetic resonance (M.R.) machine, such as gold, tungsten or platinum materials, to allow the physician to track the progress of the wire guide  10  during the medical procedure. 
     The core wire  20 , when in the retracted position  36 , is preferably completely contained within the outer component  18  so as to avoid undesirable and/or premature engagement between the anchoring portion  42  and the body vessel. This configuration permits the anchoring portion  42  of the core wire  20  to be secured within the outer component  18  without the need for a sheath, thereby minimizing part complexity and reducing the outer diameter of the wire guide. As another benefit of this configuration, the anchoring portion  42  is able to be deployed into the extended position  38  without removing a component, such as a sheath, from the wire guide  10  and without changing the outer diameter of the wire guide. 
     The core wire  20 , when in the extended position  38 , preferably extends from the aperture  52  by an extension distance  54  that is between 0.1 and 20.0 millimeters. More preferably, however, the extension distance  54  is between 2.0 and 10.0 millimeters. However, any suitable extension distance  54  may be used with the present invention. 
     The extension distance  54  may have a predetermined maximum value by providing a core wire hard stop. For example, the actuator shown in  FIG. 1  includes a base  53 , a plunger shaft  55  slidably received by a passageway defined by the base  53 , and a shoulder portion  57 . The base  53  is coupled with the outer component  18  and the plunger shaft  55  is coupled with the core wire  20  such that the core wire  20  moves with respect to the outer component  18  when the plunger shaft  55  moves with respect to the base  53 . Additionally, the shoulder portion  57  has a diameter that is greater than that of the passageway defined by the base  53  so that the plunger shaft  55  has a limited travel distance in the forward direction (as oriented from the left to the right in  FIG. 1 ). The shoulder portion  57  also serves as a convenient and simple surface to be depressed by the physician. The base  53  and the shoulder portion  57  preferably have a diameter less than of equal to the outer diameter of the wire guide  10  so that the catheter  72  is able to be advanced over the wire guide  10 . 
     In an alternative design from that shown in  FIG. 1 , the actuator base includes a pair of adjacent circular rings for receiving two of the physician&#39;s fingers and the actuator shoulder portion includes a single ring for receiving the physician&#39;s thumb. In another alternative design, the position of the core wire  20  is controlled by a removable device having an actuating mechanism, not unlike a syringe. 
     Alternatively, the physician may have broad control over the extension distance  54  by feeding a desired length of the core wire  20  through the outer component  18 . When determining the extension distance  54 , several factors may be considered, such as the thickness of the body vessel walls, the position of the anchoring portion  42  with respect to the outer component  18 , the angle at which the anchoring portion  42  extends from the outer component  18 , and the shape of the anchoring portion  42 . In one example, if the physician desires to insert the tip of the anchoring portion  42  within the body vessel wall without actually extending completely through the body vessel wall, the physician may consider the thickness of the body vessel wall, the angle at which the anchoring portion  42  extends from the outer component  18 , and the shape of the anchoring portion  42  to determine the extension distance  54 . 
     The anchoring portion  42  shown in  FIGS. 2   a  and  2   b  is a tine  56  having a tapered portion  58  for piercing and/or becoming embedded within the body vessel wall. The tine  56  has a generally curved shape so as to curl towards the body vessel wall to improve the ease at which the wire guide  10  becomes anchored to the body vessel. The curved shape of the tine  56  also creates a more secure connection between the core wire  20  and the body vessel to prevent undesirable movement of the wire guide  10 . 
       FIG. 3  shows the wire guide  10  being inserted into a body vessel  60  at an angle of entry  62  with respect to the body vessel longitudinal axis  64  during an initial stage of the wire guide delivery. During the initial stage, which includes piercing the wire guide  10  through a body vessel wall  66  and advancing the wire guide  10  along the body vessel  60  to the desired position, the core wire  20  is in the retracted position  36  to avoid snagging or becoming anchored to an inner wall  68  of the body vessel  60 . 
     Next, as shown in  FIG. 4 , the wire guide  10  is pushed along the body vessel  60  until reaching its desired location, where it engages the body vessel inner wall  68 . For example, once the distal end  14  of the wire guide  10  contacts the body vessel inner wall  68 , the core wire  20  is advanced into the extended position  38  to anchor itself to the body vessel  60 . Alternatively, the core wire  20  is advanced shortly before the distal end  14  engages the body vessel  60 , while the wire guide  10  is still being advanced forward. The anchoring portion  42  is shown in  FIG. 4  as being partially embedded within the body vessel wall  66 . More specifically, the anchoring portion  42  extends approximately half-way into the body vessel wall  66  to form a generally secure connection without extending through the body vessel wall  66 . 
     Once the wire guide  10  is anchored to the body vessel  60 , a tensile force  70  is applied to the proximal end  12  of the wire guide  10  to improve the axial stiffness of the wire guide  10 . For example, a slight force (generally less than 1 Newton) is applied along the wire guide  10  longitudinal axis  28  in a direction away from the body vessel  60  to cause the wire guide  10  to become generally taut. More specifically, a physician may pull the distal end  14  of the wire guide  10  away from the body vessel by pulling on the actuator base  53 . The taut nature of the wire guide  10  reduces the bends of the body portion  16 ; thereby reducing the points along the wire guide  10  at which a catheter  72  ( FIG. 5 ) is likely to become entangled with the wire guide  10 . Additionally, the taut nature of the wire guide  10  increases the radial stiffness of the wire guide; thereby reducing the ease at which the catheter  72  may become entangled with the wire guide  10 . The preferred magnitude of the force  70  depends on various factors, such as the type and the condition of the body vessel. For example, a body vessel in the patient&#39;s brain probably requires a smaller retraction force than a body vessel in the patient&#39;s leg. 
     Additionally, the taut wire guide  10  is able to provide improved travel by the catheter  72  through occluded or narrowed portions of the body vessel  60 . For example, the taut wire guide  10  reduces or minimizes radial movement of the wire guide  10  and thereby reduces or minimizes radial movement of the catheter  72  while moving there along. This is especially beneficial while moving through occluded or narrowed portions of the body vessel  60  where a radial movement of the wire guide  10  may increase resistance to the forward movement of the catheter  72 . Additionally, the taut state of the wire guide  10  provides counter-traction to the forward movement of the catheter  72  and reduces resistance thereto. 
     The anchoring portion  42  may be disengaged from the body vessel wall  66  by various methods, the implementation of which may depend on the shape of the anchoring portion  42 . For example, the wire guide  10  is preferably disengaged from the body vessel  60  by simultaneously applying a slight force in the forward direction (opposite to the direction of the force  70  shown in  FIG. 4 ) while pivoting the wire guide  10  about the entry point into the body vessel  60  to move the distal end  14  away from the body vessel wall  66 . Alternatively, or in addition to, the catheter  72  may be advanced until contacting the body vessel wall  66  and pushing the body vessel wall  66  away from the core wire  20 . 
       FIG. 5   a  shows the core wire in an extended position such as to extend into the wall of the body vessel wall so the catheter can be advanced along the wire guide. Additionally,  FIG. 5   b  shows the core wire  20  in an extended position  38  further advanced than that shown in  FIGS. 4 and 5   a  so as to pin the body vessel inner wall  68 . More specifically, the core wire  20  extends through the body vessel  60  wall so as to form a potentially more secure engagement therewith than in the engagement shown in  FIGS. 4 and 5   a.    
       FIGS. 6   a  and  6   b  show an alternative wire guide  110  having a spiral-shaped anchoring portion  142  that tapers as it spirals. The spiral-shaped anchoring portion  142  may be especially useful for slowly and precisely advancing the spiral-shaped anchoring portion  142  into the body vessel wall  66 . For example, the spiral-shaped anchoring portion  142  may be rotated by the physician, thereby causing the spiral-shaped anchoring portion  142  to screw itself into the body vessel wall  66 . A reverse-direction rotation can be used to remove the spiral-shaped anchoring portion  142  from the body vessel wall  66 . 
       FIGS. 7   a  and  7   b  show another alternative wire guide  210 , where the core wire includes a pair of core wire portions  220   a ,  220   b , each having an anchoring portion  242   a ,  242   b  that is able to move between a retracted position  236  and an extended position  238 . Each of the anchoring portions  242   a ,  242   b  is positioned adjacent to, or in contact with, an engagement point between adjacent coils of the coiled wire  244 , so that the anchoring portions  242   a ,  242   b  extend between the adjacent coils upon the advancement of the core wire portions  220   a ,  220   b . The anchoring portions  242   a ,  242   b  extend from side portions  276  of the outer component  218 , rather than the distal tip  251 , which may improve the ease at which the wire guide  210  is anchored to the body vessel wall. Also, the plurality of anchoring portions  242   a ,  242   b  allows more opportunities for the wire guide  210  to be anchored to the body vessel. Additionally, the anchoring portions  242   a ,  242   b  preferably are slightly curved back toward the proximal end of the wire guide  210  so as to more securely anchor within the body vessel wall. The anchoring portions  242   a ,  242   b  are preferably disengaged from the body vessel wall by pushing forward on the actuator base and pulling back on the actuator shoulder, thereby retracting the respective portions  242   a ,  242   b  into the retracted position  236 . 
       FIGS. 8   a  and  8   b  show yet another alternative wire guide  310 , where the core wire  320  splits into a pair of anchoring portions  342   a ,  342   b  that are each able to move between a retracted position  336  and an extended position  338 . Each of the anchoring portions  342   a ,  342   b  is positioned adjacent to an opening  378  defined by the outer component  318  so that the anchoring portions  342   a ,  342   b  extend through the respective openings  378  upon the advancement of the core wire  320 . The anchoring portions  342   a ,  342   b  are biased to have a spring-type force urging radially outwardly so as to extend substantially radially outwardly once they enter the openings  378 . To provide a smooth, low friction contact between the anchoring portions  342   a ,  342   b  and the outer component inner surface, the outer component  318  is preferably a solid sleeve rather than a coiled wire as described above. The anchoring portions  342   a ,  342   b  extend from side portions  376  of the outer component  318 . Additionally, the anchoring portions  342   a ,  342   b  preferably are slightly curved back toward the proximal end of the wire guide  310  so as to more securely anchor within the body vessel wall. The anchoring portions  342   a ,  342   b  are preferably disengaged from the body vessel wall by pushing forward on the actuator base and pulling back on the actuator shoulder, thereby retracting the respective portions  342   a ,  342   b  into the retracted position  336 . 
       FIGS. 9   a  and  9   b  show another alternative wire guide  410 , where the core wire  420  is a hollow tube used for the delivery of a drug into the body vessel. For example, the core wire  420  defines a passageway  480  for storing a drug and for delivering the drug to a localized portion of the body vessel. The passageway  480  has an open distal tip  482  so that the drug can be actively injected along the passageway  480  and through the open distal tip  482  or so that the drug naturally flows into or becomes absorbed by the body vessel. The drug delivery into the body vessel is advantageous over currently known methods because the drug is more locally-delivered and locally-concentrated than a general injection into the blood stream of the body vessel. The core wire  420  may also, or alternatively, be used to scrape or cut a targeted section of the body vessel. This may be accomplished by moving the actuator shoulder with respect to the base, or by moving the entire wire guide  410  with respect to the body vessel. Additionally, the core wire  420  has a generally curved portion  284  similar to that shown in  FIGS. 2   a  and  2   b  so that the wire guide  410  can be anchored to the body vessel in addition to the drug delivery function. 
     In one exemplary application, lytic agents are delivered to relatively small body vessels, such as blood vessels in the brain. In another exemplary application, chemotherapy agents are delivered to a body vessel. In yet another exemplary application, stem cells are delivered to a desired portion of a body vessel during a gene therapy procedure. The above applications, and other applications of the present invention as a drug delivery device, may be particular advantageous for targeting anatomic locations beyond the reach of standard catheters. 
     Referring back to  FIGS. 6   a  and  6   b , the wire guide  110  includes a drug delivery port  123  defined by a surface of the core wire  120  for delivering drugs to the body vessel. For example, the core wire  120  is a generally hollow tube defining a drug carrying-conduit for carrying a drug between a proximal portion of the wire guide  110  and the drug delivery port  123 . In  FIGS. 6   a  and  6   b  the drug delivery port  123  is proximal of the distal tip  151  so that the drug delivery port  123  is positioned within the bloodstream of the body vessel even when the anchoring portion  142  of the wire guide  110  is buried within the wall of the body vessel. 
       FIGS. 10   a  and  10   b  show a wire guide  510  with a similar design to that in  FIGS. 9   a  and  9   b , but with a generally linear, hollow core wire  520  that extends linearly from the outer component  518  to deliver a drug to the body vessel when in the extended position  538 . This wire guide  510  is used primarily for drug delivery, rather than for anchoring the wire guide  510  to the body vessel. 
       FIGS. 11   a  and  11   b  show yet another alternative wire guide  610 , where the anchoring portion  642  of the core wire  620  is positioned adjacent to, or in contact with, an engagement point between adjacent coils of the coiled wire  644 , so that the anchoring portion  642  extends between the adjacent coils upon the advancement of the core wire  620 , similar to the design shown in  FIGS. 7   a  and  7   b . However, in this design, the coiled wire  644  is defined by a multiple filament, helically wound row of wires  686 , similar to that disclosed in the U.S. patent application entitled “ENDOVASCULAR MEDICAL DEVICE WITH PLURALITY OF WIRES” having Ser. No. 10/615,314, which was filed on Jul. 7, 2003 and which is incorporated herein by reference. For example, the helically wound row of wires  686  includes a first wire  688  and a second wire  690  that are wound adjacent to each other in a helical pattern. The pair of wires  688 ,  690  improve the rotatability and the radial stiffness of the wire guide  610 , as well as preventing the core wire  620  from exiting the outer component  618  in an undesirable position, such as between the wrong pair of coils. For example, the outer component  618  in  FIGS. 11   a  and  11   b  has a discontinuation point  692  where the second wire  690  is terminated and a small gap  694  is present between the coils of the first wire  688 . Therefore, the core wire  620  tends to exit the outer component  618  at the gap  694 , thereby increasing the predictability of the location of the anchoring point. 
     In yet another aspect of the present invention, a wire guide having a distal portion, a proximal portion, and a body portion is provided for guidance within a body vessel. The distal portion includes an end portion for insertion into a wall of the body vessel and a stop portion having a diameter substantially greater than that of the end portion so as to resist insertion of the end portion into the wall beyond a maximum insertion distance. 
       FIGS. 12-14  show another alternative wire guide  710  generally including a proximal portion  712 , a distal portion  714 , and a body portion  716  extending between the proximal and distal portions  712 ,  714 . The distal portion  714  includes an end portion  718  for insertion into a body vessel wall and a stop portion  720  for limiting the distance that the distal portion  714  is able to be inserted into the body vessel wall. 
     The end portion  718  is sized and shaped so as to facilitate insertion into the body vessel wall. For example, the end portion  718  shown in  FIGS. 12-14  defines a generally tapered shape  722  and has a relatively sharp end tip  724 . More specifically, the end portion  718  has a diameter  726  that gradually increases from the end tip  724  towards the proximal end  712 . 
     The stop portion  720  defines an effective diameter  728  that is substantially greater than the diameter  726  of the end portion so as to prevent over-insertion of the wire guide  710  into the body vessel wall. For example, the stop portion  720  in  FIGS. 12-14  is a protrusion  732  extending generally perpendicularly to a longitudinal axis  730  of the wire guide  710 . The effective diameter  728  of the stop portion  720  and the diameter  726  of the end portion  718  are body measured along planes that are generally perpendicular to the longitudinal axis  730  of the wire guide  710 . In other words, the diameters  726 ,  728  measure the cross-sectional of the wire guide  710  taken along a plane that is perpendicular to the longitudinal axis  730 . 
     The protrusion  732  is configured to resist being bent or folded backwards towards the proximal end  712  of the wire guide so as to resist being advanced into a blood vessel wall. However, the protrusion is also configured to permit being bent or folded forwards towards the distal end  714  of the wire guide  710  so that the wire guide can be withdrawn from the blood vessel. More specifically, the proximal side  734  of the protrusion  732  defines a ramp-shaped transition surface extending from the wire guide body and the distal side  736  of the protrusion defines a generally abrupt transition surface extending perpendicularly from the wire guide end portion. 
     Referring now to  FIG. 13 , the wire guide  710  is shown disposed within a body vessel  60  and engaged with the body vessel wall  66 . More specifically, the body portion  716  of the wire guide  710  has been inserted percutaneously within the body vessel  60  and the end portion  718  has been inserted into the body vessel wall  66  so that the stop portion  720  abuts against the body vessel inner wall  68 . 
       FIG. 14  shows a sheath  738  disposed over the wire guide  710  to radially constrain the stop portion  720  and facilitate delivery of the wire guide  710  within the body vessel  60 . More specifically, the sheath  738  is a flexible sleeve that is selectively disposed on the wire guide  710  to apply a radial compressive force to the stop portion  720  while the wire guide  710  is being delivered within the body vessel  60 . As a result of the radial compressive force, the stop portion  720  is bent forward against the end portion  718  to minimize the diameter  740  of the stop portion  720 . Then, once the distal portion has been delivered within the body vessel  60 , the sheath  738  is removed from the wire guide  710  over the proximal portion  712  thereof and the stop portion  720  returns to its natural position as shown in  FIG. 12 . 
       FIG. 15  shows another alternative wire guide  810  having an end portion  818  for insertion into the wall of a body vessel and a stop portion  820  for preventing over-insertion of the wire guide  810 . Additionally, the end portion  818  includes an anchoring portion  844  for resisting removal of the end portion  818  from the body vessel wall. For example, the anchoring portion  844  shown in  FIG. 15  is a barbed portion having a shoulder surface  846  for engaging an outer surface of the body vessel wall and resisting retraction of the wire guide  810  in the direction generally indicated by reference  850 . Therefore, the stop portion  820  and the anchoring portion  844  cooperate to secure the wire guide  810  with respect to the body vessel  60  in two directions and to prevent both over-insertion and premature retraction. The end portion  818  of the wire guide  810  can be removed from the body vessel wall by pulling on the proximal end of the wire guide  810  with a sufficient force. Additionally, or alternatively, a sheath may be disposed over the wire guide  810  during delivery and/or removal of the wire guide  810  from the body vessel. 
       FIG. 16  shows another alternative wire guide  910  having an end portion  918  for insertion into the wall of a body vessel and a stop portion  920  for preventing over-insertion of the wire guide  910 . The end portion  918  has a generally circular cross-section so that the end portion  918  extends along the central axis of the stop portion  918 . As with the designs shown in  FIGS. 12 and 15 , the stop portion  920  has distal side  936  defining a generally abrupt transition surface extending perpendicularly from the wire guide end portion  918 . 
       FIG. 17  shows yet another alternative wire guide  1010  having an end portion  1018  for insertion into the wall of a body vessel and a stop portion  1020  for preventing over-insertion of the wire guide  1010 . The stop portion  1020  is a closed loop  1058  extending from the distal portion of the wire guide and having first and second ends  1060 ,  1062  attached thereto. More specifically, the ends  1060 ,  1062  extend from the distal portion of the wire guide towards the end tip of the end portion so that the loop expands when a force is applied to the loop from the distal end and compresses when a force is applied to the loop from the proximal end. 
     It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.