Abstract:
An endovascular device tip assembly and method of making the same, incorporating a radiopaque marker usable with catheters and other suitable endovascular devices is provided. The tip assembly incorporates a radiopaque marker device by providing a counterbore within a primary bore of a tubular tip of an endovascular device. The marker device is fitted securely within the counterbore and the tubular tip is further deformed distally of the marker in order to secure the marker within the device.

Description:
BACKGROUND  
       [0001]     This application claims priority to U.S. Provisional Application 60/792,779, filed on Apr. 17, 2006.  
         [0002]     The present application relates to an endovascular device tip assembly incorporating a marker and the method of making the same. Moreover, this application relates to the use of a radiopaque marker that is fixed within a medical device, such as a catheter, by counterboring the distal end of a tubular device and placing the marker within.  
         [0003]     Endovascular devices have long been known which can be surgically inserted into a body lumen, such as an artery, to reinforce, support, repair, or otherwise enhance the performance of the lumen. For example, catheters generally include a hollow tubular portion, usually formed of resilient plastic, for insertion through the skin of a patient into a cavity, duct or vessel to permit injection or withdrawal of fluids, or to deliver medications to patients for therapeutic reasons. Regardless of the instrument, the accurate placement of the instrument in the patient&#39;s body is often critical to its successful use.  
         [0004]     As a result, different methods have been developed to help the physician “see” inside of the patient&#39;s body and help determine exactly where the endovascular device is being positioned. For example, X-ray, MRI, CT, and ultrasound devices and techniques have been employed. The endovascular devices may still be difficult to position without some enhancement of the device. Medical devices which incorporate radiopaque materials may more accurately position the various medical implements.  
         [0005]     Typically, the distal tip of an endovascular device consists of a hollow metal or polymer cylinder which is tapered along the outer surface. The inside diameter of the tip is typically sized to allow the smooth passage of a guidewire of a given diameter. Preferably, the inside diameter remains constant. Therefore, it is desirable to develop a method of incorporating a marker into the tip of an endovascular device without changing the inner diameter of the tip, which would make it more difficult to pass a guidewire therethrough. This invention addresses such a method for incorporating a marker into the tip of an endovascular device.  
       BRIEF SUMMARY  
       [0006]     The endovascular tip device described below may overcome the aforementioned problems and relates to a medical device, and more particularly, to an endovascular tip device assembly and method of making the same that incorporates a radiopaque marker device within the tip assembly.  
         [0007]     A method of incorporating a marker into an endovascular device tip is disclosed. This method comprises providing a tubular tip of an endovascular device comprising a distal end portion and at least one longitudinal bore extending therethrough, the distal end portion comprising at least one outlet opening and the at least one longitudinal bore having an internal diameter; creating a counterbore through the distal end portion of the tubular tip, thereby increasing the internal diameter of the at least one longitudinal bore; providing a marker device; positioning the marker device within the counterbore, the marker device having a first end and a second end; and deforming a portion of the tubular tip extending distally beyond the second end of the marker device to retain the marker device within the counterbore.  
         [0008]     The method described above wherein the internal diameter of the at least one longitudinal bore is approximately equal to an internal diameter of the marker device.  
         [0009]     The method described above wherein the marker device is cylindrically shaped.  
         [0010]     The method described above wherein the cylindrical marker device comprises radiopaque material.  
         [0011]     The method described above wherein the marker device is about 0.01 to about 0.125 inches in length.  
         [0012]     The method as described above, wherein the internal diameter of the counterbore is approximately from about 0.001 inches to about 0.125 inches larger than the internal diameter of the at least one longitudinal bore.  
         [0013]     The method described above wherein the internal diameter of the counterbore is approximately 0.004 inches larger than the internal diameter of the at least one longitudinal bore.  
         [0014]     The method described above wherein the at least one longitudinal bore is further defined by an outer radial surface and an inner radial surface; and wherein the counterbore is further defined by a first end and a second end defining a ledge between the inner surface of the at least one longitudinal bore and an inner radial surface of the counterbore; and wherein the first end of the marker device is adjacent the ledge.  
         [0015]     The method described above, wherein the ledge is approximately 0.0005 to about 0.0625 inches thick and the marker device has a thickness approximately equal to the ledge.  
         [0016]     The method described above wherein the ledge is approximately 0.002 inches thick and wherein the marker device has a thickness approximately equal to the ledge.  
         [0017]     An endovascular tip device manufactured according to the method as described above.  
         [0018]     An endovascular device is disclosed comprising: a tubular tip of the endovascular device having a distal end portion and a proximal end portion, the distal end portion having an internal diameter larger than an internal diameter of the proximal end portion; a radiopaque marker having a first end and a second end and being disposed within the distal end portion; and the distal end portion having a length deformed distally of the second end portion of the radiopaque marker.  
         [0019]     The endovascular device described above wherein the length extending beyond the second end of the marker is approximately 0.05 cm to about 2.0 cm.  
         [0020]     The endovascular device described above wherein the length extending beyond the second end of the marker device is deformed by heat tapering the length and gradually decreasing the internal diameter of the distal end, securely affixing the marker tubular tip.  
         [0021]     The endovascular device described above wherein the tubular tip is formed integrally on a distal end of a catheter body.  
         [0022]     The endovascular device described above wherein the tubular tip is bonded on a distal end of a catheter body. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]      FIG. 1  is side view of the tip of an endovascular device and the marker device in a final configuration of the present invention;  
         [0024]      FIG. 2  is side view an endovascular device prior to incorporation of the counterbore;  
         [0025]      FIG. 3  is side view an endovascular device prior to incorporation of the marker device; and  
         [0026]      FIG. 4  is side view of the tip of an endovascular device and the marker device in an untapered configuration. 
     
    
     DETAILED DESCRIPTION  
       [0027]     An exemplary embodiment of the present invention may be described in use with any endovascular device, but for the purposes of this application, will be referred to as a catheter. To be clear, the tip assembly will be described in accordance with the following method, but other equivalent methods are contemplated by the invention.  
         [0028]     Referring now to  FIG. 1 , the method of the present invention for incorporating a marker within a tip of an endovascular device, for example a catheter, includes providing a tubular tip  10  of any desired length having a primary bore  12  for directing fluids or mechanical devices, such as stents, to and from the body of the patient. The tubular tip  10  may be integral with the catheter body of a single lumen catheter system, such as a balloon catheter. On catheter based systems that include multiple lumens, the tip may be integral with the innermost lumen. Alternatively, the tubular tip may be glued or heat molded to the outermost catheter body. This technique may result in a larger overall profile of the distal end of the catheter-based system.  
         [0029]     As shown in  FIG. 2 , the tubular tip  10  of a catheter body includes a distal end portion  14  and a proximal end portion  16 . The distal end portion  14  may define an outlet opening  18  of the primary bore  12 . The tubular tip  10  also may include an annular side wall  20  having an outer radial surface  22  and an inner radial surface  24  further defining the bore  12  of the tip  10 . The tubular tip  10  of the catheter body may be formed of any appropriate material which may be inserted into the human body, but is preferably formed of a flexible material such as nickel-titanium alloys, polyethylene, nylon, PVC, polyurethane or silicone. The tubular tip  10  may also include various support structures, such as woven or helical reinforcements. The reinforcements may be in the form of wires or bands.  
         [0030]     The inner radial surface  24  of the side wall  20  may include a first inner diameter D 1 . The first inner diameter D 1  may generally be between about 0.010 inches to about 0.25 inches, and may desirably be about 0.017 inches wide. Generally, the side wall  20  of the catheter body may be about 0.004 inches thick, measured from the outer radial surface  22  to the inner radial surface  24  of the bore  12 . Alternatively, the side wall  20  may range from about 0.001 to about 0.125 inches thick.  
         [0031]     Referring now to  FIG. 3 , the method further includes forming a counterbore  26  within the tip  10 . The counterbore  26  is generally created within the distal end portion  14  of the tubular tip  10 . The counterbore  26  may be created in an unmodified tube in a variety of ways. Preferably, but not limited to, the inner radial surface  34  of the bore  12  may be prepared by drilling or grinding the counterbore  26  into the distal end portion  14  of the tubular tip  10 . The counterbore  26  may also be formed during the molding process of the catheter body or may be cut or reformed into the tip after the catheter is formed.  
         [0032]     Starting at or about the outlet opening  18  of the tip  10 , the counterbore  26  may be formed within the annular side wall  20  of the catheter body, lengthwise, toward the proximal end portion  16  of the tubular tip  10 . The counterbore  26  provides an enlarged inner diameter, or a secondary inner diameter D 2 , within a portion of the bore  12 . The counterbore  26  may decrease the thickness of the side wall  20  by approximately half of the original wall thickness. One embodiment of the present invention includes a wall thickness of about 0.004 inches. The resulting secondary inner diameter D 2  may be about 0.014 to about 0.254 inches, depending on the original thickness of the initial inner diameter of the tip  10 . For example, if D 1  is originally 0.017 inches, the resulting inner diameter of the bore D 2  would be approximately 0.021 inches.  
         [0033]     The proximal end  28  of the counterbore  26  generally forms a ledge  30  within the tubular tip  10  of the catheter body. This ledge  30  is generally the same thickness of the marker  32  that is to be incorporated into the tip  10 . Such a marker  32  may generally be about 0.002 inches thick. The thickness of the marker and the ledge generally correspond to the size of the counterbore.  
         [0034]     Referring now to  FIG. 4 , the method further includes providing a cylindrical band, marker  32 , formed of a radiopaque, or other suitable, material having an outer diameter D 3  which generally corresponds to the secondary inner diameter D 2  of the tubular tip  10  as defined by the inner radial surface  34  of the counterbore  26 , and an inner diameter DA 4 , generally corresponding to D 1 . The marker  32  may be formed of an x-ray reflective, or radiopaque, material which may be viewed by the physician via radiography, fluoroscopy, or other usual visualization techniques. The marker may be a cylindrical metal sleeve, formed of palladium, iridium, gold, tantalum, tungsten, platinum, or other suitable radiopaque material. It is also contemplated that the marker may be a radiopaque polymer, such as radiopaque nylon. Bismuth, barium, and tungsten are examples of suitable fillers that may be used to make polymers radiopaque.  
         [0035]     Preferably, the marker is a cylindrical sleeve, but it also may be a split cylinder, a half moon shape, a radiopaque ring, or other suitable shape that would allow the marker to be friction fit or otherwise secured within the counterbore of the tubular tip.  
         [0036]     The marker  32  is incorporated into the catheter body within the distal end portion  14  of the tip  10  so as to accurately mark the position of the distal end of the catheter when exposed to x-rays. The marker  32  may be a cylindrical band having an outer radial surface  42  and an inner radial surface  40  defining a center bore which terminates at a first end  36  and at a second, opposite end  38 . The first end  36  of the marker  32  may be manually positioned adjacent the ledge  30  of the counterbore  26  so that the inner radial surface  40  of the cylindrical marker  32  extends no further radially inward than the inner radial surface  24  of the bore  12  of the tubular tip  10  of the catheter body. As a result, the inner radial surface  24  of the bore  12  is substantially constant without interruptions or inwardly extending ridges formed by the first  36  and second ends  38  of the cylindrical marker  32 . The marker may also be placed within the counterbore by use of an automated machine, and it may be molded in to the counterbore upon formation of the tip.  
         [0037]     Because the inner radial surface  24  of the tip  10  remains substantially constant, it prevents the formation of internal restrictions in the primary bore  12  thereby maintaining a constant inner diameter D 1  and D 4 .  
         [0038]     Also, because the marker  32  is positioned within the inner radial surface  24  of the tip  10 , the outer radial surface  22  may remain smooth. A smooth outer radial surface  22  is advantageous on many medical instruments that are to be inserted into a patient&#39;s body since the outer surface slides against the patient&#39;s skin and internal tissue. A smooth outer surface  22  allows the medical instrument to more easily be pushed through a patient&#39;s skin or other openings with small clearances while minimizing harm to the patient.  
         [0039]     Referring again to  FIG. 1 , in order to securely incorporate the marker  32  of the present invention into the catheter body, the method of the present invention further includes deforming or tapering the distal end portion  14  of the tip  10  that extends beyond the second end  38  of the marker  32 . One way to taper the tip  10  is by heating and/or applying pressure to the distal end portion  14 . The tip  10  may be reformed to a desired diameter, generally accommodating the diameter of the wire guide to be used with the device. The wall of the tip  10  may also be formed around the marker  32  so that a portion of the wall abuts the second end  38  of the marker  32 , further securing the marker  32  within the device.  
         [0040]     In use, the tubular tip  10  of the endovascular device is inserted into a patient&#39;s body to perform one or more of a variety of functions including the delivery and withdrawal of fluids and mechanical devices such as stents. As is apparent, the present invention may be used to incorporate radiopaque markers  32  formed of various suitable materials in to many different types of endovascular devices including delivery catheters, angioplasty balloons and other endoscopic instrumentation.  
         [0041]     When the device is positioned in the patient&#39;s body and the body is exposed to x-rays, the radiopaque marker  32  provides a clear indication to the physician as to the precise location of the marked portion of the instrument. The marker  32  may also be provided with indicia marked or etched into the outer surface of the band. These indicia may be visible when exposed to x-rays during use so as to assist the physician in the procedure by, for example, distinguishing the catheter from an adjacent catheter.  
         [0042]     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.