1. Technology Field
The present invention generally relates to intraluminal catheters, such as balloon and stent delivery catheters, used in intravascular systems. In particular, the present invention relates to a catheter tip having features that facilitate intraluminal passage of the catheter when twisted guidewires are present in the passage.
2. The Related Technology
Angioplasty and stent implantation procedures are commonly employed to treat lesions or blockages that form within the vascular anatomy of a patient. During an angioplasty, or percutaneous transluminal coronary angioplasty (“PTCA”) procedure, for instance, a guiding catheter is advanced through the vasculature of the patient to a desired point, such as the ostium of a predetermined coronary artery. A guidewire, positioned within a balloon catheter, is extended from a distal end of the guiding catheter into the patient's coronary artery until it penetrates and crosses a lesion to be dilated. The balloon catheter is then advanced through the guiding catheter and over the previously introduced guidewire, until it is properly positioned across the lesion.
Once properly positioned, the balloon is inflated to a predetermined size such that the stenosis of the lesion is compressed against the arterial wall, thereby expanding the passageway of the artery. The balloon is subsequently deflated, blood flow resumes through the dilated artery, and the balloon catheter is removed.
Occasionally, post-procedure restenosis, or reformation of the arterial blockage, occurs after the PTCA procedure has been performed. To reduce the incidence of restenosis and strengthen the dilated area, physicians frequently implant an intravascular prosthesis, generally called a stent, inside the artery at the site of the lesion. During a stent implantation procedure, a stent is delivered in a contracted state on a balloon catheter to the desired location within a coronary artery. Once properly positioned, the stent is expanded to a larger diameter via expansion of the balloon, which causes the stent to expand against the arterial wall at the lesion site. The balloon is then deflated and it and the catheter are withdrawn. The expanded stent remains in place within the artery at the site of the dilated lesion, holding the vessel open and improving the flow of blood therethrough.
Lesions are often located at or near a point of bifurcation in an artery or other body vessel. When treating such bifurcated lesions, it is common to first place a first guidewire in the main branch, then place a second guidewire, extending from the main branch, into the side branch of the vessel bifurcation. During its placement, it is often necessary to rotate, or torque, the second guidewire in order for the tip thereof to engage the ostium of the side branch. Torquing the second guidewire in this manner occasionally results in the second guidewire intertwining with the first guidewire such that twists between the two guidewires are present within the main vessel branch proximate the bifurcated lesion region.
Intertwining of the two guidewires within the vessel as described above can significantly complicate proper placement of the balloon catheter at the bifurcated lesion region. Specifically, when it is tracked over the first guidewire, the balloon catheter meets with these twists of the second guidewire about the first guidewire. If the balloon catheter is then advanced further along the first guidewire, a “plowing” effect occurs, wherein the twisted second guidewire is slid along with the balloon catheter as it proceeds distally along the first guidewire. Undesirably, this causes a tightening of the twists of the second guidewire about the first guidewire within the vessel.
Should the second guidewire twists become too tight about the first guidewire, a pinching force can be imposed by the second guidewire on the tip of the balloon catheter, thereby impeding or preventing further advancement of the balloon catheter within the vessel. The unfortunate results of this situation include compromised catheter placement, possible damage to vessel structure, etc.
In light of the above discussion, a need exists in the art for a catheter system capable of use with multiple guidewires employed in treating intravascular lesions at bifurcated regions. In particular, a catheter configuration is needed that alleviates problems occasioned by the advancement of the catheter along a first guidewire when a second guidewire is twisted thereabout. Any solution to the above need should prevent or reduce plowing of the twisted second guidewire as the catheter is advanced, so as to avoid binding of the catheter tip caused by the tightening of the second guidewire twists. Moreover, any proposed solution should be adaptable for use with a variety of catheter types and configurations.
The present invention has been developed in response to the above and other needs in the art. Briefly summarized, embodiments of the present invention are directed to a catheter tip for attachment with an intravascular balloon catheter that is used within a body lumen. The catheter tip includes a body portion having a base that is attached to the balloon catheter. The base defines a proximal end of the catheter tip. A head that is attached to the body portion defines a distal end of the catheter tip. An axial cavity, cooperatively defined by the body portion and the head, extends longitudinally from the proximal to the distal end of the catheter tip. The axial cavity receives a first guidewire along which the catheter is moved within the body lumen. An outer surface of the head is shaped in a predetermined manner to control the magnitude of deflection of a second guidewire that is often twisted about the first guidewire in the lumen so as to prevent catheter obstruction by the guidewires during catheter procedures. The outer surface of the catheter tip head can define various shapes, including rounded, tapered, and bulbous shapes.
The body portion is defined by a coiled wire having a predetermined pitch. This coiled configuration lends flexibility to the catheter tip, enabling it to ease passage of the balloon catheter through the body lumen. In one embodiment, the body portion of the tip is z encapsulated with a covering material that further optimizes passage of the balloon catheter.
These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Reference will now be made to figures wherein like structures will be provided with like reference designations. It is understood that the drawings are diagrammatic and schematic representations of exemplary embodiments of the invention, and are not limiting of the present invention nor are they necessarily drawn to scale.
The catheter tip is further configured to enable the catheter to track through vessels where a second guidewire is positioned with the first guidewire in a main branch and extends into a side branch of the vessel, known as a bifurcated lumen, to treat a lesion proximate the bifurcation. As the second guidewire often twists about the first guidewire in the main vessel branch, the catheter tip is shaped and configured to enable passage of the catheter through such regions without causing a tightening of the second guidewire twisting, which can cause wedging of the catheter between the guidewires and prevent advancement of the catheter to the lesion. Further, the catheter tip is designed so as to prevent pinching of the first guidewire by the tip, another common consequence of twisting between the first and second guidewires. In addition, embodiments of the present invention provide for a flexible tip design, thereby easing advancement of the catheter through the vessel lumen.
Reference is first made to
As best shown in
The wire from which the coil 20 is formed is stainless steel in the present embodiment. In other embodiments, other suitable materials can be used to compose the wire. For instance, and not by way of limitation to the possible materials usable to form coil 20, the coil 20 can be formed from a metal, metal alloys, shape memory material, polymer, plastic, synthetic material, natural material, combinations thereof, or other material having the desired material characteristics and properties to aid with moving the catheter along the guidewire. Also, though the cross sectional shape of the wire here is circular, other cross sectional shapes can alternatively be used.
The coil 20 is further shaped such that both the body and base portions 12 and 14 of the tip 10 define a decreasing taper from the proximal end 18A to the point of attachment with the head 16. In the present embodiment the taper has a magnitude of approximately 1.5 degrees, though other taper amounts can alternatively be used. For example, and not by way of limitation to the above, the taper can have an angular orientation of from about 0 degrees to about 30 degrees, depending upon the particular application.
The tapered coil described above lends flexibility to the catheter tip 10, which in turn assists the catheter in tracking along the relatively tortuous vasculature of a patient's body during the angioplasty, stent placement, or other procedure. The taper defined by the coiled wire 20 of the body and base portions 12 and 14 further shapes the tip for relative ease in catheter advancement.
It is noted that, though separately identified above, the base portion can be integrally formed with the body portion of the catheter tip in the present embodiment. In other embodiments, however, the base portion, like the head in the above embodiment, can be separately defined then attached to the body portion of the tip. Moreover, the coiled wire shown in
The body portion 12, base portion 14, and head 16 cooperate to define an axial cavity 24 that longitudinally extends between the proximal and distal ends 18A-B of the tip 10. The cavity 24 is configured to receive a first guidewire (
The distal end 18B of the head 16 includes an annular face 30 circumscribing the opening of the cavity 24. As illustrated in
The head 16 further defines an outer surface 32. In accordance with the present embodiment, the head 16 has a hollow cylindrical shape with the outer surface 32 defining an outer head diameter of approximately 0.50 mm, and the axial cavity 24 of this portion being defined by an inner head diameter of approximately 0.42 mm. The axial length of the head outer surface 32 here is approximately 0.50 mm. Though defining a cylindrical shape here, the head outer surface in other embodiments can be shaped so as further assist catheter travel through the vessel, as will be seen further below. Further, these dimensions, of course, are exemplary, and should not be construed as limiting the present invention in any way. For example, and not by way of limitation, the outer head diameter can range from about 0.4 mm to about 10 mm, the inner head diameter can range from about 0.2 mm to about 9 mm, and the axial length of the head out surface can range from about 0.05 mm to about 50 mm.
Like the coiled wire 20, the head 16 can be formed from stainless steel or other suitable material. For instance, and not by way of limitation to the possible materials usable to form head 16, the head 16 can be formed from a metal, metal alloys, shape memory material, polymer, plastic, synthetic material, natural material, combinations thereof, or other material having the desired material characteristics and properties to aid with moving the catheter along the guidewire. A suitable material includes one whose hardness prevents deformation of the head during intravascular travel and interaction of the tip with the guidewires disposed within the vessel. This in turn enables the size of the cavity 24 defined through the tip 10 to be reduced so as to minimize the clearance between the outer diameter of the guidewire and the inner diameter of the head 16, as additional cavity clearance to compensate for deformation of the head—which otherwise would cause binding of the head on the guidewire—is not necessary.
Manufacture of the head from a relatively hard material also enables the radial thickness of the head 16 to be minimized as well. This in turn reduces the annular thickness of the annular face 30 of the head 16, which assists the tip 10 in passing through guidewire twists or penetrating obstructing lesions within the vessel, as will be explained.
Reference is now made to
Reference is now made to
A second guidewire 44 is also shown disposed within the vessel lumen. The first guidewire 42 is positioned in a main branch of the vessel, while the second guidewire—though having a portion in the main branch as shown in
To position the guidewires as described above, the first guidewire 42 is first inserted into the main vessel branch to a predetermined location. The second guidewire 44 is then introduced into the main vessel branch and advanced until it is positioned within the side branch of the vessel at the point of bifurcation. In order to maneuver the second guidewire to entry into the side branch, it is often necessary to rotate, or torque, the second guidewire as it advances through the main vessel branch. Such torquing of the second guidewire 44 typically results in the second guidewire loosely twisting about the first guidewire 42 in the main vessel branch. This situation is shown in
Once the first and second guidewires 42 and 44 are positioned in the main and side vessel branches, respectively, the catheter 40 is introduced into the vessel and tracks along the first guidewire as it is advanced through the main branch toward the point of vessel bifurcation. As it advances along the first guidewire 42, the catheter 40 encounters the twists of the second guidewire 44 about the first guidewire.
The tip 10 of the catheter 40 is configured to enable the catheter to advance through and past such guidewire twists without causing a tightening of the twists, which would otherwise progress of the catheter. Specifically, and as shown in
Advancement of a catheter having a catheter tip as described in accordance with embodiments of the present invention is further assisted by the head 16B being composed from a relatively hard material, such as stainless steel. In instances where some slight wedging of the catheter 40 between the first and second guidewires 42 and 44 occurs, the relative hardness of the tip head 16B ensures that deformation thereof will not result, which as mentioned could otherwise cause the head to bind on the first guidewire passing therethrough.
Further, the relative hardness of the tip head 16B enables it to be made with a minimized clearance for the axial cavity 24, thereby further reducing the overall profile of the tip head 16, which in turn increases the ability of the catheter 40 to pass through the second guidewire twists or to penetrate an obstructing vessel lesion. Moreover, the general flexibility of the catheter tip body and base portions 12 and 14 provided by the coiled wire 20 further assists catheter passage through the vessel lumen.
The passage process of the catheter 40 past the second guidewire twists continues during catheter advancement through the vessel until all of the twists have been passed or until the catheter is properly positioned at a lesion site. Note that, though the catheter tip head design shown in
Reference is now made to
In the present embodiment, the laser cut achieved is a cross sectionally square cut having approximate dimensions of 0.05 mm×0.05 mm. The laser cut is further made so as to impart a 0.25 mm pitch P4 to the coil 120. The coil 120 can be composed of three separate laser cut coils spirally defined adjacent one another, though in other embodiments fewer or more coils can be defined in the tip 100, including the possibility of a single continuous spiral cut to define the coil. Again, the tip 100 has a taper shape, tapering down from the proximal end 118A to the head 116. The taper, pitch, and other dimensions of the tip and laser cut of the coil can, of course, be modified from what is described herein. For example, and not by way of limitation, the cross-sectional square cut dimensions can range from about 0.01 mm×0.01 mm to about 1 mm×1 mm, while the pitch can range from about 0.01 mm to about 10 mm, depending upon the particular application. Further, it will be understood that the laser cut need not have a square cut, but can have various other cut configurations, such as rectangular for instance.
As the tip 100 is manufactured from a single stock piece, the head 116 is integrally formed with the body portion 112 and base portion 114. These components therefore integrally define an axial cavity 124 extending longitudinally between the proximal and distal ends 118A and 118B.
Reference is now made to
The body and base portions 12 and 14 of the catheter tip 10 are substantially z covered by a covering material, or encapsulant 150, composed of a suitable material such as plastics and polymers, including but not limited to PEBAX, vinyl, nylon, polyurethane or other materials suitable for use with the catheter. The head 16A can remain uncovered. The encapsulant 150 can be applied to the catheter tip 10 so as to preserve the desired dimensions of the cavity 24 and outer surface portions of the base and body portions 12 and 14. Application of the encapsulant 150 to the catheter tip 10 can occur in one of several ways, including molding, dipping, etc., and can occur either before or after the tip is attached to the catheter.
Though its use has been discussed herein in connection with its use in PTCA and stent implantation procedures, the catheter tip and associated catheter can also be modified for use in treating chronic total occlusions (“CTOs”), wherein the relatively hard head of the tip enables penetration through the fibrous cap commonly present with such occlusions—something not always possible with softer tipped catheters.
Note that a catheter tip configured in accordance with the embodiments described herein can be attached to the balloon or other suitable catheter in one or more of a variety of ways including, for example, friction fit, thermal or chemical adhesive, mechanical fasteners, circumferential connectors, etc. In the latter case, for instance, a band of wire or other suitable connector can be secured about the base portion 14 of the catheter tip 10 shown in
In those embodiments where the catheter tip is not encapsulated, the distal portion of the catheter can be softened by heating and the proximal end of the catheter tip inserted therein such that a portion of the proximal end is embedded in the distal portion of the catheter, thereby joining the two components.
Reference is now made to
In
Yet another catheter tip configuration is shown in
Though the embodiments shown herein include catheter tips composed of a metal, in one embodiment the catheter tip head and body portion can be formed from a polymeric material, such as PEEK, for instance. Such a composition could be especially applied to the braided catheter tip configuration shown in
Reference is now made to
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims the benefit of the U.S. Provisional Patent Application No. 60/780,752, filed Mar. 9, 2006, and entitled “Contoured Stent and Delivery System with Novel Tip Design,” which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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60780752 | Mar 2006 | US |