Patent Application
20100087780
The present invention generally relates to a medical surgical device and specifically a wire guide for percutaneous placement within a body lumen. The flexibility of the wire guide may be varied while it is in place within the body lumen.
Wire guides are commonly used in vascular procedures, such as angioplasty procedures, diagnostic and interventional procedures, percutaneous access procedures, or radiological and neuroradiological procedures in general, to introduce a wide variety of medical devices into the vascular system. For example, wire guides are used for advancing intraluminal devices such as stent delivery catheters, balloon dilation catheters, atherectomy catheters, and the like within body lumens. Typically, the wire guide is positioned inside the inner lumen of an introducer catheter. The wire guide is advanced out of the distal end of the introducer catheter into the patient until the distal end of the wire guide reaches the location where the interventional procedure is to be performed. After the wire guide is inserted, another device such as a stent and stent delivery catheter is advanced over the previously introduced wire guide into the patient until the stent delivery catheter is in the desired location. After the stent has been delivered, the stent delivery catheter can then be removed from a patient by retracting the stent delivery catheter back over the wire guide. The wire guide may be left in place after the procedure is completed to ensure easy access if it is required.
Conventional wire guides include an elongated wire core with one or more tapered sections near the distal end to increase flexibility. Generally, a flexible body such as a helical coil or tubular body is disposed about the wire core. The wire core is secured to the flexible body at the distal end. In addition, a torquing means can be provided on the proximal end of the core member to rotate, and thereby steer a wire guide having a curved tip, as it is being advanced through a patient's vascular system.
A major requirement for wire guides and other intraluminal guiding members, is that they have sufficient stiffness to be pushed through the patient's vascular system or other body lumen without kinking. However, they must also be flexible enough to pass through the tortuous passageways without damaging the blood vessel or any other body lumen through which they are advanced. Efforts have been made to improve both the strength and the flexibility of wire guides to make them more suitable for their intended uses, but these two properties tend to be diametrically opposed to one another in that an increase in one usually involves a decrease in the other.
For certain procedures, such as when delivering stents around challenging take-off, tortuosities, or severe angulation, substantially more support and/or vessel straightening is frequently needed from the wire guide. Wire guides that provide improved support over conventional wire guides have been commercially available for such procedures. However, such wire guides are in some instances so stiff they can damage vessel linings when being advanced.
In other instances, extreme flexibility is required as well. For example, when branched or looped stents are to be delivered to a branched vascular region, it is beneficial to insert the wire guide from the branch where a stent is to be located. However, the stent may need to be introduced and guided from a separate branch. In this situation, the wire guide is inserted into the patient's vascular system near the desired stent location and a grasping device is inserted in the branch from which the stent will be introduced. The wire guide may be advanced back along the branch to provide the grasping device access to the distal end of the wire guide. However, the wire guide should be extremely flexible to allow grasping and manipulation of the wire guide without damaging the tissue around the bifurcation formed by the luminal branch. Further, the wire guide should be extremely kink resistant to avoid damaging the wire guide as it is grasped. After the wire guide is retrieved by the grasping device, the stent may be delivered over the wire guide to the desired location. However, available wire guides are not designed to provide the flexibility required to cross up and over the bifurcation of the luminal branch and yet also provide the stiffness required to aid in the insertion of the stent.
In view of the above, it is apparent that there exists a need for an improved design for a wire guide.
One aspect provides a wire guide having variable flexibility. In one embodiment, the wire guide includes a coil defining a lumen, a distal tip positioned at the distal end of the coil and a plurality of core members positioned side by side within the lumen. At least one of the core members is attached to the distal tip and extends from the distal tip to the proximal end of the coil. The wire guide may also include a band positioned around the core members and holding the core members together. In one embodiment, at least one of the core members can be moved axially with respect to the coil, and can move proximally and away from the distal tip. In another embodiment, the core members can have a square or rectangular cross section.
In yet another embodiment, the wire guide also includes a handle attached to the proximal end of the coil. The handle includes a plurality of adjustment members, one of which is attached to one of the core members and is movable axially to vary the axial position of that core member. The handle may also include graduated markings indicating the axial position of the core member.
In another embodiment, at least one of the core members includes stainless steel, a stainless steel alloy, platinum, palladium, a nickel-titanium alloy or combinations thereof. In yet another embodiment, the coil is a multifialar coil.
Another aspect provides a method of varying the flexibility of a wire guide positioned within a body lumen of a patient. The method includes inserting the distal end of a wire guide as disclosed above into the body lumen and varying the axial position of the one of the plurality of core members.
a)-(c) are partial cross sections along the length of illustrative wire guides.
a)-(b) are partial cross sections along the length of one embodiment of an illustrative wire guide.
In accordance with an embodiment of the present invention, a wire guide system includes a wire guide having a mechanism allowing the flexibility of the wire guide to be variable while the wire guide is in place within a body lumen of a human or animal patient (“patient”).
The terms proximal and distal are used herein to refer to portions of a wire guide. As used herein, the term “distal” is defined as that portion of the wire guide closest to the end of the wire guide inserted into the patient's body lumen. The term “proximal” is defined as that portion of the wire guide closest to the end of the wire guide that is not inserted into the patient's body lumen. The terms distally and proximally are used herein to refer to directions along an axis joining the proximal and distal portions of the wire guide (“axial direction”). For example, proximal movement is movement towards the proximal portion of the wire guide. Distal movement is movement towards the distal portion of the wire guide.
Reference is now made to
In one embodiment, core members 50 and 60 can be moved axially with respect to distal tip 20 so as to vary the position of the distal ends of these core members with respect to distal tip 20. By doing so, the flexibility of the distal portion of wire guide 10 is varied. In another embodiment, the distal end of core member 40 is attached to distal tip 20 and cannot be moved axially with respect to distal tip 20. In yet another embodiment, the distal end of core member 40 is not attached to distal tip 20. In this embodiment, core members 40, 50 and 60 can be moved axially with respect to distal tip 20. A safety wire can be included in this embodiment to prevent excessive extension of coil 30.
b) illustrates a partial view of another embodiment of wire guide 10. In this embodiment, band 70 is positioned around core members 40, 50 and 60 to hold the core members together within the lumen of coil 30 while allowing axial movement of the members in a proximal-distal direction. Of course, more than one band may be positioned along the length of the core members.
a) and 2(b) illustrate the distal portion of a wire guide including four core members 120, 130, 140 and 150 positioned within the lumen of coil 170. In
Control of the variation in flexibility of the wire guide may be increased by including additional core members within the coil of the wire guide. The present embodiments include wire guides having 2, 3, 4, 5, 6, 7 or more core members. In one embodiment, the core members are positioned side-by-side within the lumen of the wire guide coil. For the purposes of the present embodiments, core members are considered to be positioned side-by-side then they are bundled together in any configuration within the lumen of the coil.
In other embodiments, the core members have a rectangular cross section.
In another embodiment, at least one of the core members includes a protrusion shaped to engage an indentation in another core member.
In certain embodiments, the core members are manufactured from a material such as stainless steel, a stainless steel alloy, platinum, palladium, a nickel-titanium alloy, such as NITINOL®, or combinations of these materials. Inclusion of a radiopaque material, such as platinum or gold, into the core members allows for better visibility during manipulation of the wire guide within the body of the patient. In certain embodiments, a radiopaque material is included in portions of one or more core members, for example, at the distal end of a core member. Where one or more of the core members are attached to distal tip of the wire guide, the attachment may be by methods including, but not limited to, adhesive, solder or laser welding.
The coil of the wire guide may be a single filar coil or a multifilar coil. Alternatively a cable tube may be used. The use of a multifilar coil or a cable tube may eliminate the need for a safety wire, allowing all of the space within the lumen of the coil to be occupied by the core members.
The coil may be formed from any suitable material including, but not limited to stainless steel, alloys including stainless steel, a nickel-titanium alloy, such as NITINOL®, or combinations of these materials. In certain embodiments, the wire guide includes a coating on at least a portion of the surface of the coil. The coating can include a material that reduces the coefficient of friction on that surface. For example, the coating may include a polymer such as, but not limited to, a fluoropolymer.
The external diameter of the coil and the number and shape of core members may be chosen to obtain a required wire guide size and flexibility. The dimensions given below are illustrative of some typical configurations and dimensions. In one embodiment, the external diameter of the coil is between 0.040 inches and 0.010 inches. In another embodiment, the external diameter of the coil is between 0.020 inches and 0.010 inches. In yet another embodiment, the external diameter of the coil is between 0.040 inches and 0.020 inches. In one embodiment the wire guide is formed from a coil having an external diameter of approximately 0.035 inches. In another embodiment, the wire guide is formed from a coil having an external diameter of approximately 0.015 inches.
The wire guide may also include a handle attached to the proximal end of the coil. In one embodiment the handle includes a plurality of adjustment members, one of which is attached to each of the movable core members. Each of the adjustment members can be moved axially and provides a means of varying the axial position of the attached core member. The handle may also include graduated markings indicating the axial position of the core members. A stop member limiting the extent of proximal movement of at least one of the core members may also be included.
Another aspect provides a method of varying the flexibility of wire guide while it is in place within the body of a patient. Referring again to
Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope and spirit of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appended claims and equivalents thereof.
