Abstract:
A stent assembly including a catheter formed with a side aperture, and a deflector positioned near the side aperture adapted to deflect a guidewire pushed thereagainst to pass through the side aperture.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to stents, and particularly to a catheter with structure to redirect a guidewire that facilitates implanting bifurcated stents in a body.  
       BACKGROUND OF THE INVENTION  
       [0002]     A stent is a well known device used to support an intraluminal wall, used in procedures, such as but not limited to, percutaneous transluminal coronary angioplasty (PTCA). Various types of stent architectures are known in the art, including braided stents (filaments or wires, wound or braided into a particular configuration), or mesh stents (metal mesh bent or formed into a particular shape), among others.  
         [0003]     Typically, a stent may be restrained in a radially compressed configuration by a sheath or catheter, and delivered by an introducer to the site where it is required. The introducer may pass over a guidewire (like a monorail) that has been entered through the patient&#39;s skin, or through a blood vessel exposed by minor surgical means. When the introducer has been threaded into the body lumen to the stent deployment location, the introducer is manipulated to cause the stent to be released. The stent expands to a predetermined diameter at the deployment location, and the introducer is withdrawn. Stent expansion may be effected by spring elasticity, balloon expansion, or by the self-expansion of a thermally or stress-induced return of a shape memory alloy (such as a nickel-titanium alloy, e.g., NITINOL) to a pre-conditioned expanded configuration.  
         [0004]     There are bifurcated lumens, such as but not limited to, the carotid artery, which may need support with a bifurcated stent. A bifurcated lumen (also called bifurcation) is an area of the vasculature where a first vessel is bifurcated into two or more branch vessels. Stenotic lesions may form in or around such bifurcations, that is, in or around one or more of the vessels.  
         [0005]     However, delivering and deploying a stent to support a bifurcated lumen is a difficult challenge. Some of the problems include the difficulty of properly orienting the stent with respect to the bifurcation and the difficulty of providing a stent that supports the main trunk and branches of the bifurcation without blocking the passageways or causing turbulence or other flow disruptions.  
         [0006]     PCT patent application PCT/IL03/00814 to Henry Israel, describes a bifurcated stent assembly with a stent sheath that includes two individually removable portions, one removable in a distal direction and the other in a proximal direction.  
         [0007]     U.S. Pat. No. 6,494,905 to Zedler et al. describes a balloon catheter for use in the region of a vessel branching and, in particular, in coronary vessels. The catheter comprising a catheter stem disposed at the distal end of which are provided at least one balloon and at least one first guide means arranged in the region thereof for positioning the balloon in the region of a vessel branching. The first guide means is adapted to be introduced into the lateral branch of the vessel transversely with respect to the longitudinal direction of the balloon catheter. The balloon comprises at least two chambers which are spaced from each other in the longitudinal direction of the balloon catheter and between which the first guide means is arranged  
         [0008]     U.S. Pat. No. 6,761,734 to Suhr describes a segmented balloon catheter for use in treating a condition of a blood vessel occurring near a bifurcation. The catheter comprises a shaft which includes a proximal end, a distal end and a longitudinal passageway that extends therethrough from the proximal end to the distal end. A first balloon portion is mounted on the shaft adjacent the distal end, and a second balloon portion is mounted on the shaft adjacent the first balloon portion. The shaft also comprises a transverse port which extends between the longitudinal passageway and the exterior of the segmented balloon catheter from between the first and second balloon portions. In this manner, a proximal end of a first guide wire which is pre-positioned in the main vessel may be inserted into the distal end of the shaft and threaded through the longitudinal passageway and out the proximal end of the shaft, and a proximal end of a second guide wire which is pre-positioned in the side branch vessel may be inserted into the transverse port and threaded through the longitudinal passageway and out the proximal end of the shaft.  
         [0009]     A problem of the prior art stent assemblies is that the stent/catheter must be slid over a double guidewire (i.e., a pair of guidewires). At some point along the travel over the guidewires, the stent/catheter tends to twist and bind or otherwise get snagged, hindering the travel of the stent to the desired site.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention seeks to provide a catheter configuration that facilitates implanting bifurcated stents in a body, and which may be useful in deploying a guidewire through a side aperture of a main stent into a bifurcation of a blood vessel, for example. In one embodiment, a main stent may be deployed over the guidewire, and then the same guidewire may be redirected through a side aperture of the catheter to enable deploying a branch stent through that aperture. This obviates the need for working with two guide wires or trying to push a second guidewire through the side aperture.  
         [0011]     There is provided in accordance with an embodiment of the present invention a stent assembly including a catheter formed with a side aperture, and a deflector positioned near the side aperture adapted to deflect a guidewire pushed thereagainst to pass through the side aperture.  
         [0012]     In accordance with an embodiment of the present invention, the deflector may include a flap formed in a side wall of the catheter. The deflector may be spaced from an inner side wall of the catheter by a gap. A guidewire may be disposed in the catheter, wherein pushing the guidewire against the deflector deflects the guidewire through the side aperture.  
         [0013]     In accordance with another embodiment of the present invention, the deflector may be directionally resilient to permit a guidewire to pass therethrough in one direction only. In such an embodiment, the deflector acts like a one-way valve. Main and branch stents may be assembled with the catheter and introduced over the same guidewire. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0014]     The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawing in which:  
         [0015]      FIG. 1  is a simplified pictorial illustration of a stent assembly, constructed and operative in accordance with an embodiment of the invention, including a catheter introduced into a body lumen over a guidewire, and including a deflector near a side aperture of the catheter;  
         [0016]      FIG. 2  is an enlarged illustration of the deflector of the catheter of  FIG. 1 ;  
         [0017]      FIG. 3  is a simplified pictorial illustration of the guidewire being pulled to the proximal side of the deflector;  
         [0018]      FIG. 4  is a simplified pictorial illustration of the guidewire being pushed against the deflector and being deflected into a branch lumen of the bifurcation; and  
         [0019]      FIG. 5  is a simplified illustration of introducing a branch stent over the branch guidewire and through the side aperture, in accordance with an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0020]     Reference is now made to  FIG. 1 , which illustrates a stent assembly  10 , constructed and operative in accordance with an embodiment of the invention. Stent assembly  10  may include a catheter  12 , which may be passed over a guidewire  14  to enter a body lumen  16 , such as but not limited to a blood vessel. As is well known in angioplasty, guidewire  14  may be introduced by means of an introducer sheath (not shown) inserted through some lumen (e.g., femoral artery), and guidewire  14  is manipulated through vasculature to the site of implanting the stent. Guidewire  14  may be grasped and manipulated (e.g., pushed, pulled, twirled and twisted) at its proximal end, and may be constructed of any suitable material for guidewires, as is well known in the art.  
         [0021]     A main stent  18  may be initially disposed in catheter  12  in a contracted orientation prior to deployment (this option shown in  FIG. 1 ), and slides over guidewire  14  together with catheter  12 . In such an embodiment, the main stent  18  is a self-expanding stent, which may be constructed from a suitable material, such as but not limited to, a shape memory alloy (such as a nickel-titanium alloy, e.g., NITINOL). Main stent  18  may be a wire mesh or braided stent, or any other kind of stent, but the invention is not limited to this construction or to self-expanding stents. For example, without limitation, stent  18  may be balloon-expandable, constructed from a suitable material, such as but not limited to, stainless steel 316L. In such an embodiment, the stent  18  is disposed over the catheter  12  (this option shown in  FIG. 4 ). In general, stent  18  is “assembled with” the catheter  12 , which encompasses self-expanding, balloon-expandable and any other kinds of stents. Stent  18  may be coated, such as a drug-eluting stent that has a polymer coating that emits an anti-restenosis drug. Stent  18  may be formed with a side opening  20  and catheter  12  may be formed with a side aperture  22  for placing therethrough a branch stent, as is described hereinbelow.  
         [0022]     Reference is now made additionally to  FIG. 2 . In accordance with an embodiment of the invention, catheter  12  may include a deflector  24  that enables deflecting guidewire  14  through side aperture  22 , as is explained further below. In one non-limiting embodiment, deflector  24  may be constructed by laser cutting or otherwise forming a flap in a side wall  26  of catheter  12 . The flap may be bent into the catheter and becomes deflector  24 . The opening left in the side wall  26  becomes side aperture  22 . The area may be heat treated as necessary. Of course, the invention is not limited to this construction and the deflector  24  may be formed in other ways from other materials. In general, deflector  24  may be constructed of any metal, plastic or other materials that are medically safe.  
         [0023]     Deflector  24  may be sized and shaped so that deflector  24  is spaced from the inner side wall  26  by a gap  28 . Guidewire  14  may initially pass through gap  28 , as seen in  FIG. 2 , wherein catheter  12  slides over guidewire  14  to the site of a bifurcation, and the main stent  18  is positioned at the bifurcation.  
         [0024]     Referring to  FIG. 3 , guidewire  14  may be pulled proximally in the direction of an arrow  30  to be on the proximal side of deflector  24 . As seen in  FIG. 4 , guidewire  14  may then be pushed distally in the direction of an arrow  32  against deflector  24 . Deflector  24  deflects the guidewire  14  so that it passes through side opening  20  of main stent  18  and through side aperture  22  of catheter  12  into a branch lumen  34  of the bifurcation.  
         [0025]     Reference is now made to  FIG. 5 . Another catheter  36  may be slid over guidewire  14 . A branch stent  38  may be initially disposed in catheter  36  in a contracted orientation prior to deployment, and slides over guidewire  14  together with catheter  36 . As described hereinabove for main stent  18 , branch stent  38  may be a wire mesh or braided stent, or any other kind of stent, e.g., balloon-expandable or self-expanding, and may be coated, such as a drug-eluting stent. The branch stent  38  may be introduced through the side opening  20  of main stent  18  into the branch lumen  34 . Upon withdrawal of catheter  36 , branch stent  38  may expand or be otherwise deployed in branch lumen  34 .  
         [0026]     It is noted that the terms “push” and “pull” are relative terms and encompass any suitable motion and are not limited to the strict sense of push or pull. Also, the terminology of “sliding” a catheter over a guidewire is meant to encompass any kind of motion of the catheter with respect to the guidewire, such as but not limited to, monorail fashion.  
         [0027]     Additionally or alternatively, deflector  24  may be directionally resilient or flexible (the terms being used interchangeably) to permit guidewire  14  to pass therethrough in one direction only, e.g., only in the proximal direction (arrow  30 ) not in the distal direction (arrow  32 ). Deflector  24  thus acts like a one-way valve (e.g., deflector  24  may be constructed as a spring-loaded flap). In such an embodiment there is no need for gap  28 , rather the guidewire  14  can move proximally through the deflector  24 , but when pushed distally against the deflector  24  gets deflected through the side aperture  22 . The directional resilience of deflector  24  may be controlled through choice of materials, heat treatment and geometry, for example. Of course, it is appreciated that the invention may alternatively be carried out wherein the deflector  24  permits guidewire  14  to pass through distally and not proximally.  
         [0028]     As another alternative, shown in  FIG. 1 , deflector  24  may be formed with a hole  40  through which guidewire  14  may originally pass. As described above, guidewire  14  may be pulled proximally to the proximal side of deflector  24  and then pushed distally against deflector  24 .  
         [0029]     The invention may be carried out with any kind of stent, such as but not limited to, the balloon catheters shown in U.S. Pat. No. 6,494,905 to Zedler et al. or U.S. Pat. No. 6,761,734 to Suhr.  
         [0030]     It is appreciated that various features of the invention which are, for clarity, described in the contexts of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.