Patent Publication Number: US-2007106245-A1

Title: Infusion guidewire

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates generally to catheters and guidewires of the type used in the medical profession for infusion of fluids and/or medicaments to a tissue site within the body and, more specifically, the present invention provides an improved infusion guidewire that can be used both in the infusion of a fluid at desired location within body lumen of a patient and can function to facilitate placement of catheters and other devices into a body lumen of a patient.  
      Medical guidewires and catheters are devices that can be introduced into and navigated through blood vessels and other narrow passages in the body. These devices can be navigated through the blood vessels until the distal end of the device is positioned in the desired location. Guidewires are typically used for introduction of a catheter over the guidewire.  
      One of the purposes for a guidewire is the positioning of a catheter used to infuse a liquid at a given location in a patient&#39;s blood vessel (i.e., infusion catheter). Cardiovascular guidewires used for this purpose are typically constructed to have a solid core wire and are dimensioned such that they are capable of being received within a catheter lumen as the catheter is advanced over the guidewire. Thus, a guidewire is typically first inserted into a blood vessel and an operator (e.g., physician) controls the advancement and resulting position of the distal end of the guidewire by manipulations performed at the proximal end outside the body. Then, when the guidewire is positioned in the desired location, a catheter is advanced over the guidewire, and the guidewire may either be left in place or withdrawn to leave only the catheter in the blood vessel. One distinct advantage of guidewires in general, is their ability to go into small lumens at distal locations. They allow access to remote areas with the ability to guide larger devices into place. Additionally, they can also pass through very narrow openings, such as severely stenosed vessels.  
      Infusion catheters generally include a hollow lumen that functions both to receive a guidewire and to allow passage of fluid therefrom and a fluid outlet for delivery of fluid at a distal portion of the catheter. An exemplary perfusion catheter is described in U.S. Pat. No. 6,669,662, wherein the catheter includes a shaft having a lumen and a plurality of ports through the shaft. The catheter further includes a rotatable core with a core groove disposed within the lumen. The plurality of ports can be exposed by retraction of the core and the core can be rotated within the shaft. U.S. Pat. No. 6,063,069 describes an infusion catheter used for power lysis of thrombus. The infusion catheter is formed with a catheter lumen extending from a proximal end connector assembly to a distal end valve that is normally closed but is penetrable to allow introduction of a guidewire through the catheter lumen and a distal end valve to allow advancement of the infusion catheter over the guidewire, thereby allowing access of the distal infusion segment to the desired location.  
      Infusion catheters, however, typically do not possess the requisite rigidity necessary for unaided advancement in a blood vessel and, therefore, must be used in conjunction with a guidewire. Because the multiple steps of using an infusion catheter in conjunction with a guidewire have disadvantages (e.g., increased procedure time, increased invasiveness, etc.), attempts have been made to fabricate a device that can be advanced in a patient&#39;s blood vessel without the use of an additional guidewire and which also functions for infusing a liquid. As a result, infusion devices have been produced having the rigidity required for advancement through a patient&#39;s blood vessel and include a hollow lumen for carrying and infusing a liquid. Such devices often are a hybrid of multiple components that are found in standard guidewires and catheters. In particular, the devices typically include a wire coil portion and a sheath portion either surrounding the wire coil or positioned within the wire coil, with the two portions defining a lumen therein. Illustrative examples are provided as follows:  
      U.S. Pat. No. 5,211,636 teaches an infusion guidewire with a guidewire body having a helical coil with a flexible nonporous sheath within the lumen. The helical coil is close wound along the majority of its length, but the distal end of the helical coil has spaced windings to permit infusion of the fluid.  
      U.S. Pat. No. 6,027,461 discloses an infusion guidewire/catheter having an integral, tapered core wire within an infusion lumen formed of the aligned lumens of the conduit of a proximal connector housing, a proximal inner sheath in a proximal guidewire portion of a distal coil wire in a distal guidewire portion. A plurality of infusion side holes are formed in a distal infusion segment of the outer sheath in fluid communication with the infusion lumen. A similar device is taught in U.S. Pat. No. 5,997,487.  
      U.S. Pat. No. 4,932,419 teaches a flexible catheter-like guidewire which has a multi-filar, cross-wound coil body terminating in a distal ball tip element. The body has an inner coil and an outer coil, each formed by multiple coil wires, that define an elongated lumen, which can hold a fluid for deliver to the distal tip of the device.  
      U.S. Pat. No. 6,059,767 teaches medical guidewires and catheters that include tubular bodies having coils at their distal ends to permit steering through the vasculature, where the devices are used for delivering fluids to a target site, draining fluids, and infusing medicaments.  
      Despite these advances, a need remains for improved infusion guidewire assemblies and methods that allow rapid, controlled, and efficacious infusion of a liquid to a desired location in a body lumen or vessel. For example, the multiple sheath and coil layer construction of the existing devices can restrict the cross-sectional lumen area available for fluid deliver. Furthermore, coiled layers making up large portions the guidewire shafts, including the infusion segments, can limit controlled infusion due to bending, contraction and expansion of the coils. Therefore, there is a need for improved infusion assemblies that are dimensioned such that they are suitable for use as a traditional guidewire (e.g., introduction and positioning of other devices, such as a catheter) as well as for infusion of a liquid at a desired location in a body lumen, and wherein the infusion assembly does not require a guidewire shaft having multiple sheath and coil layers.  
     BRIEF SUMMARY OF THE INVENTION  
      In one aspect of the invention, an infusion guidewire assembly is provided. The infusion guidewire assembly includes a guidewire shaft having a distal end, a proximal end and a fluid delivery lumen therethrough. The guidewire assembly further includes an infusion hub adapted to be removably mounted on the proximal end of the guidewire shaft, wherein the hub provides fluid connection to the fluid delivery lumen; and a guidewire coil attached to the distal end of the guidewire shaft. The guidewire coil may be shapeable or may have a preformed deflection, and in either case will usually be isolated from the fluid delivery lumen of the guidewire shaft. The guidewire shaft of the assembly includes a plurality of infusion ports formed over a distal region proximal to the guidewire coil.  
      The guidewire shaft, according to the present invention, is dimensioned as to maintain the general functionality of a guidewire as understood in the medical arts. In particular, the guidewire shaft of the assembly can be advanced or positioned in a body lumen of a patient (e.g., blood vessel), for example, by application of manual compression, tension and torque to the proximal end of the guidewire which remains outside the patient. Furthermore, once the guidewire is positioned in the desired location within a body lumen, a catheter or other device can optionally be advanced over the guidewire shaft.  
      In one embodiment, for example, the guidewire shaft has an outer diameter in the range of about 0.25 mm to about 1.25 mm. The guidewire shaft further includes a fluid delivery lumen therethrough which is dimensioned to fluidically connect the proximal end of the guidewire shaft (typically via the hub) with the infusion ports. The size of the fluid delivery lumen of a shaft can vary, for example, according to the desired application of the guidewire assembly, as well as the properties of a fluid (e.g., viscosity) to be disposed in the delivery lumen in a particular application of the assembly. In one embodiment, for example, the guidewire shaft includes a fluid delivery lumen with a diameter in the range of about 0.15 mm to about 1 mm.  
      The fluid infusion ports are formed over a distal region of the guidewire shaft and will be dimensioned such that a fluid disposed in the fluid delivery lumen can be infused from the fluid delivery lumen through the ports and infused into an area outside the guidewire shaft. The size of the infusion ports can vary and the port size selected may depend, for example, on the intended application of the guidewire assembly and/or the properties of a fluid (e.g., viscosity) to be disposed in the guidewire of the invention and infused through the ports. In one embodiment, for example, the infusion ports can have a width in the range from about 0.05 mm to about 0.4 mm. The geometry of the infusion ports can vary. Often, the ports will have a generally circular shape so that the width is equal to the diameter. In other cases, however, they may have an ovoid or other regular non-circular geometry. In other instances, the ports could be asymmetric and/or have irregular geometries. The range of widths set forth above will generally refer to the maximum width across the center or centroid of the infusion port.  
      The plurality of infusion ports are formed over a distal region of the guidewire shaft that is proximate to the guidewire coil. Both the orientation of the ports and the pattern of distribution over a region of the guidewire shaft can vary, for example, based on the intended use of the assembly. The infusion ports, for example, can be in the form of slots, holes, or any geometrical configuration suitable for infusing a liquid from the lumen of the guidewire shaft to an area adjacent to the ports. The infusion ports can be densely formed over a relatively short segment (e.g., 0.2 cm to 5 cm) of the distal region or can be more sparsely populated over a longer segment including, for example, up to the entire length of the guidewire shaft. In one embodiment, the plurality of ports can include 1 to 50 infusion ports spaced over a distal length in the range from about 0.5 cm to about 15 cm. Ports can be oriented and distributed circumferentially and/or in a longitudinal fashion on the shaft of the wire or oriented in a spiral configuration on the guidewire shaft.  
      In one embodiment of the invention, the infusion guidewire assembly can further include an injection device which may be removably connected to the infusion hub. The infusion hub, according to the current invention, typically includes a distal end that can be removably connected to and in fluid communication with the guidewire shaft, for example, at the proximal end of the guidewire shaft. The proximal end of the infusion hub can be removably connected to an injection device. The infusion hub can further include a fluid input port located between the proximal and distal ends of the infusion hub. In operation, fluid may be introduced into the infusion hub via the fluid input port or the injection device through the proximal end of the infusion hub. The injection device may include, for example, a fitting or fluid port for connection of a reservoir or fluid source to the infusion guidewire assembly. In one embodiment, the injection device includes a syringe. In other embodiments, the injection device may include an indaflator, a pump, an infusion pouch, or the like.  
      In another aspect, the invention includes a method treating a body lumen, typically a blood vessel. The method includes providing an infusion guidewire assembly, positioning a shaft of the assembly in a body lumen, introducing an interventional catheter over the guidewire while the guidewire remains positioned within the body lumen, and infusing an agent through infusion ports in a shaft of the guidewire proximal to a distal guidewire coil.  
      A fluid introduced into a body lumen of a patient can comprises a variety of agents, including, for example, pharmaceutically active agents or medicaments suitable for treating a body lumen or ameliorating a condition in the body lumen. In one embodiment, the agent is a thrombolyitc agent. In other embodiments, the fluid can include agents that inhibit, e.g. prevent or ameliorate or conditions such restenosis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view of a guidewire infusion assembly according to one embodiment of the present invention.  
       FIGS. 2A through 2C  illustrate different arrangements of the infusion ports over the distal end of the guidewire shaft.  
       FIG. 3  illustrates use of the infusion guidewire for delivering an agent into a blood vessel in accordance with the methods of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  is a cross-sectional view of a guidewire infusion assembly  10  according to an embodiment of the present invention. The assembly includes a guidewire shaft  12  having a distal end  14 , a proximal end  16 , and a fluid delivery lumen  18 . An infusion hub  20  can be adapted to be removably mounted on the proximal end  16  of the guidewire shaft  12 . The infusion hub  20  provides a fluid connection to the fluid delivery lumen  18 . A guidewire coil  22  additionally is attached to the distal end  14  of the guidewire shaft  12 . The shaft  12  of the guidewire includes a plurality of ports  24  formed over a distal region of the shaft  12  that is proximal to the guidewire coil  22 . Usually, but not necessarily, the fluid delivery lumen  18  will be isolated from the guidewire coil  22 , for example by a barrier  23  at the distal end of the guidewire shaft  12 . In this way, all fluid delivered through the fluid delivery lumen  18  will be infused into the target body lumen via the plurality of ports  24 .  
      The guidewire shaft  12  is of a composition and design such that the guidewire shaft  12  of the assembly  10  can be advanced or positioned in a body lumen of a patient, for example, by application of manual compression, tension and/or torque to the proximal end of the guidewire, e.g. by manually manipulating the hub  20 . The guidewire shaft  12  can be composed of any material having flexibility and torqueability suitable for use of the guidewire as described herein, while maintaining a small cross sectional diameter (e.g., less than about 1.5 mm). In one embodiment, the guidewire shaft  12  is composed of a nickel titanium alloy material marketed under the trademark “NITINOL”. In other embodiments, the guidewire shaft  12  may be composed of a spring stainless steel.  
      The shaft  12  of the guidewire is dimensioned as to permit use of the guidewire assembly  10  for advancement and positioning, as described above, and for delivery of a fluid through the fluid delivery lumen  18 . In one embodiment, the guidewire shaft  12  has an outer diameter in the range from about 0.25 mm to about 1.25 mm. The diameter of the fluid deliver lumen  18  of the guidewire shaft  12  can vary and may be selected, for example based on the intended application of the device and/or the properties of the fluid utilized (e.g., viscosity). In one embodiment, the fluid delivery lumen  18  is in the range of about 0.15 mm to about 1 mm. The length of the guidewire will depend on its intended use. For vascular uses, the length may vary in the range from 50 cm to 300 cm, typically being in the range from 60 cm to 190 cm.  
      In one embodiment, the distal end of the assembly includes a guidewire coil  22 , which can aid the positioning of the guidewire through a body lumen of a patient. The guidewire coil  22  is constructed of a flexible coil segment  28 , wherein the distal end of the coil segment  28  terminates in a tip  30 . The tip  30  can be rounded in order to allow the tip  30  to more easily slide past a contacted surface, such as an interior wall of a patient&#39;s body lumen (e.g., blood vessel wall). The coil segment  28  is flexible and capable of bending laterally. In some instances, the coil segment  28  may be shapeable so that a user may pre-shape the tip into the desired non-linear configuration. In other instances, the coil segment  28  may have a permanent preformed bend or deformation to prevent steering of the guidewire through the vasculature or other body lumens.  
      The guidewire assembly  10  further includes an infusion hub  20  adapted to be removably mounted on the proximal end  16  of the guidewire shaft  12 . The infusion hub  20  provides fluid connection to the fluid delivery lumen  18  and can optionally be removed, for example, to allow the infusion guidewire to function as an ordinary guidewire to facilitate placement of other devices (e.g., catheters), though removal is not necessarily required for such use. In one embodiment, the infusion hub  20  is mounted to the proximal end  16  of the guidewire shaft  12  via a valved connection  32 , such as a hemostasis valve. The infusion hub  20  according to the invention typically includes at least one fluid port  34  suitable for the input and/or output of fluid. The fluid port  34  can further be fluidically connected with a fluid reservoir, syringe, or other fluid source.  
      As noted above, the guidewire shaft  12  includes a plurality of fluid infusion ports  24  formed over a distal region of the shaft  12  that is proximal to the guidewire coil  22 . The size, number, distribution, and shape of the plurality of infusion ports  24  is varied in alternate embodiments depending upon the intended application of the guidewire assembly, including, for example, the flow rate to be achieved and/or the properties of the fluid (e.g., viscosity) to be infused through he ports  24 . In one embodiment, the infusion ports  24  can have a width in the range of about 0.05 mm to about 0.4 mm.  
      The infusion ports  24  are of any geometrical configuration suitable for fluid flow through the ports  24 , including infusion of a liquid from the lumen  18  to an area adjacent to the ports  24  and can include, for example, slots, holes, etc. The infusion ports  24  can be formed over guidewire distal region segments of varying length, including, for example, a relatively short segment (e.g., about 0.2 cm to about 5 cm) to relatively longer segments (e.g., greater than 5 cm and up to the entire length of the guidewire shaft). The density of infusion port distribution over the guidewire shaft can vary according to the desired application of the assembly. In one embodiment, the plurality of ports can include 1 to about 50 infusion ports spaced over a distal length in the range from about 0.5 cm to about 15 cm. Ports can be oriented and distributed circumferentially and/or in a longitudinal fashion on the shaft of the wire or arranged in a spiral or helical configuration on the guidewire shaft.  
      Referring now to  FIGS. 2A through 2C , exemplary circular perfusion ports  24  on guidewire shaft  12  are illustrated in  FIG. 2A . The circular ports  24  are arranged in axial lines spaced apart by 90° on four quadrants of the shaft. While only two or three ports  24  are shown on each axial line, it will be appreciated that greater or lesser numbers could also be employed. The guidewire shaft  12  having rectangularly slotted infusion ports  24  is illustrated in  FIG. 2B . Again, the rectangular slotted ports  24  are arranged in four axial lines on 90° quadrants of the shaft. The number of ports may vary and the spacing may also vary. Referring now to  FIG. 2C , smaller circular ports  24  arranged in a spiral pattern over the distal region of the shaft  12  are illustrated.  
      In use, the distal end of the guidewire is introduced into a body lumen BL ( FIG. 3 ) of a patient (e.g., blood vessel) and the shaft  12  is positioned in the desired location. Once the shaft  12  is in position, a fluid is introduced into the fluid delivery lumen  18  and directed out of the fluid infusion ports  24 , as shown by arrows  31 , thereby delivering the fluid to an area of the body lumen proximate to the infusion ports  24 . Alternatively, it will be understood that the assembly might be utilized in removing fluid from a body lumen rather than introducing a fluid into a body lumen. In such an embodiment, fluid in the body lumen is drawn through the infusion ports  24  and into the fluid lumen  18 , for example, by application of negative pressure to the fluid lumen.  
      Fluid infusion may be achieved by a variety of conventional techniques. For example, fluid may be infused by connecting port  34  to a fluid-filled bag which is suspended sufficiently high above the patient so that the fluid will flow under gravity. Alternatively, port  34  may be connected to a peristaltic or other fluid pump which produces a positive pressure which will cause the fluid to flow through the lumen  18  and out of the infusion ports  24 . As a third alternative, the port  34  may be connected to a syringe for manual introduction of the fluid.  
      A fluid infused according to the present invention can include a variety of agents and is not intended to be limed to any particular agent or class of agents. An infused fluid can include pharmacologically active agents or medicaments suitable for treating, ameliorating, or preventing a variety of conditions, such as stenosis. An agent can include a thromolytic agent, such as plasminogen activators or heparin compounds. Alternatively, a fluid can be saline or other biologically neutral fluid and/or may be used primarily for rinsing a body lumen. Agents can include imaging agents or contrast agents used for medical imaging purposes.  
      It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. Numerous different combinations are possible, and such combinations are considered to be part of the present invention.