Abstract:
An intraluminal cutter having an expandable, rotary cutter with a plurality of cutting blades designed to cut and remove tissue proliferation within a stent and also to reopen stents. The intraluminal cutter is placed within the lumen of the clogged stent and expanded. By rotary movement of the expanded cutter blades, the device cuts and removes the material within the lumen. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to limit the scope or meaning of the claims.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to an intraluminal cutter for trimming ingrowth from the inside of stents or other shunts.  
         BACKGROUND OF THE INVENTION  
         [0002]    Current ways of dealing with tumor ingrowth into a lumen of a metallic stent include putting a second stent within the stent, or placing a catheter across or placing a covered stent within the stent. The covered stents are not readily available in the United States, and may become crimped by the tumor mass within the primary stent. Cleaning the lumen of the stent from the tumoral ingrowth may be a better alternative, even when a second stent is planned to be inserted.  
           [0003]    Accordingly, there is a need for intraluminal cutters for many applications including, but not limited to, biliary stents and TIPS shunts.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention meets the above-described need by providing an expandable, rotary cutter having a plurality of cutting blades designed to cut and remove tissue proliferation within stents, and reopen stents. The intraluminal cutter is placed within the lumen of the clogged stent and expanded. By rotary movement of the expanded cutter blades, the device cuts and removes the material within the lumen. Cleaning out the lumen of the stent/shunt with the cutter is superior to prior art methods and devices for reintroducing flow through the stent.  
           [0005]    These and other features and advantages of the present invention will become more apparent to those skilled in the art by reference to the following description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which:  
         [0007]    [0007]FIG. 1A shows a bile duct tumor with a metal stent within the tumor;  
         [0008]    [0008]FIG. 1B shows the bile duct tumor of FIG. 1A with the metal stent within the tumor but with ingrowth within the lumen of the stent;  
         [0009]    [0009]FIG. 1C shows the intraluminal cutter in action, through a percutaneous access, debulking the tumor ingrowth with the lumen of the stent, with particles of removed tissue migrating distally;  
         [0010]    [0010]FIG. 2A shows a metal stent after removal of the guide wire;  
         [0011]    [0011]FIG. 2B depicts ingrowth of tissue along the inner surface of the shunt;  
         [0012]    [0012]FIG. 2C shows balloon angioplasty in the area of the ingrowth tissue;  
         [0013]    [0013]FIG. 2D shows the removal of the tissue growth within the stent with the current invention cutter device;  
         [0014]    [0014]FIG. 3 is a sectioned side elevation of the intraluminal cutter of the present invention;  
         [0015]    [0015]FIG. 4 is a partial view of the intraluminal cutter, showing the rotary cutter blades in the contracted or closed position;  
         [0016]    [0016]FIG. 5 is an end view of the device showing the cutter blades in the closed position;  
         [0017]    [0017]FIG. 6 is an end view of the device showing the cutter blades in the open position; and,  
         [0018]    [0018]FIG. 7 is a sectioned lumen in which a stent is present, demonstrating the rotational action of the device in removing the ingrown tissue. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    The present invention is disclosed in connection with biliary stents and TIPS shunts, however, it is to be understood that the present invention may be used for stents and shunts used in other vessels.  
         [0020]    Referring to FIGS.  1 A-C, palliation of obstructive, unresectable tumors causing occlusion of the bile flow through the bile ducts  2 , is a major indication for percutaneous biliary drainage in patients with malignant lesions  3 . Biliary drainage is initially performed with a catheter, followed by an endoprosthesis implant, if indicated. The rationale for using a catheter or metal stent is to improve bile flow and counteract the complications caused by the biliary obstructive process and cholestasis (stasis of bile within the liver). Major symptoms and complications of biliary duct obstruction include jaundice (accumulation of bile salts in the body), pain, pruritis, anorexia and weight loss.  
         [0021]    Biliary catheters are effective drainage devices, but are left hanging out of the patient skin, connected or not to a bag. Catheters need to be exchanged every four to six weeks, because they become clogged up by bile debris and accumulation of bile salts and proteins in the lumen and walls. Catheters are, therefore, considered to be temporary means of bile duct drainage.  
         [0022]    The biliary endoprosthesis or stents  4  are designed to be more comfortable to the patients, do not connect with the exterior and offer a much larger lumen for internal biliary drainage. The durability of a metallic stent is certainly longer than a plastic internal stent or a percutaneous drainage catheter, however, it is still limited by the almost certain tumor ingrowth through the wire mesh of the stent walls.  
         [0023]    Turning to FIGS.  2 A-D, another common problem related to stent obstruction is encountered in the TIPS procedure. TIPS (transjugular intrahepatic portosystemic shunt) in which a wire mesh stent is implanted via catheter between the portal and hepatic venous circulation, creating a new vessel within the liver, is the most recent development in the management of portal hypertension. The shunt, similar to the surgical one, relieves high portal vein pressure caused by progressive occlusion of portal vessels at the level of microcirculation, in patients with advanced liver cirrhosis. In the past, the only option was a surgical bypass that has high morbidity and mortality risks and led to a long inpatient recovery. In addition to these problems, the surgical operation was so extensive, it was rarely appropriate for the sickest patients.  
         [0024]    In contrast, TIPS has proven to be a relatively safe, well-tolerated and reliable means of palliation for portal hypertension, and it can be offered to a much wider range of patients. The typical patient is admitted with upper GI bleeding from varices that develop when circulation in their cirrhotic liver shuts down and the pressure in the portal vein goes up. Although the bleeding can be stopped with esophageal balloon catheters and endoscopic sclerosis of varices, that does not treat the portal hypertension that is causing the bleeding. The procedure is especially useful in transplant centers where a number of patients are waiting in line for an organ for transplantation. Patients that can benefit from the TIPS procedure are liver transplant candidates, reducing the complications of portal hypertension, such as controlling variceal bleeding, development of ascites and encephalopathy, gaining time as they wait for an available organ.  
         [0025]    The TIPS procedure can be briefly described as follows. After a guide wire has been passed from the jugular vein through the vena cava and into the hepatic vein  6 , a needle-tipped catheter is used to pierce the hepatic vessel wall  7  punch through about a few centimeters of liver tissue and enter the portal vein  8 . Pressure measurements are made in both veins to provide a baseline for evaluating gradient changes after stent placement. A guide wire is advanced into the portal vein. The catheter is advanced over the wire.  
         [0026]    Following balloon dilation of the new passage, a stainless steel mesh stent  9  is expanded into the opening. Contrast dye is injected to confirm patency and check for proper positioning of the stent, and the new pressure gradient is recorded for comparison with the baseline.  
         [0027]    The new mesh stent used for the shunt may develop occlusion in 20% to 50% of the patients, which will require a second intervention to open. Most commonly the occlusion will be caused by ingrowth of the tissue along the inner surface of the shunt. Interventions to open the stent are usually performed with balloon angioplasty, and new stent placement. A new way to clean the lumen of the TIPS shunt would be to remove the tissue ingrowth within the stent with the cutter of the present invention, rather than perform a balloon angioplasty or new stent placement.  
         [0028]    Referring to FIG. 2 d , a basket  200  is deployed in spaced apart relation to the distal end of the cutter  10 . The basket  200  is deployed over a guide wire by means of a sheath introducer and is deployed distally relative to the cutter  10 .  
         [0029]    Referring to FIGS.  3 - 7  and initially to FIG. 3, the intraluminal cutter  10  of the present invention is deployed to the target lumen over a guide wire  13 . The guide wire  13  passes through the inside of the cutter  10  along its longitudinal axis  14 . The cutter  10  includes a set of deformable yet resilient blades  16 . The blades  16  comprise a plurality of axially deformable cutting blades that extend in the radial direction from a closed position shown in FIG. 4 to a fully expanded position shown in FIG. 3.  
         [0030]    At the distal end  18 , the blades  16  are attached to a retaining collar  19 . At the proximal end  20  of the blades  16 , the blades  16  are attached to tubing  22 . Tubing  22  extends to an external control device  25  including a two-piece handle  26  that is operated outside of the patient by the interventionist.  
         [0031]    A fitting  28  at the end of the tubing  22  is attached to the external control device  25 . The external control device  25  includes a first portion  31  that is fixedly attached to the tubing  22  through fitting  28 . Rotation of the first portion  31  rotates the tubing  22  which results in rotation of the blades  16  on cutter  10 .  
         [0032]    A second portion  34  of the external control device  25  is attached to the first portion  31 . As described in greater detail below, the second portion  34  is capable of rotating and is also capable of translational movement relative to first portion  31  along the longitudinal axis  14  of the device.  
         [0033]    A second tube  40  is fixedly attached to the second portion  34  at a first end and moves independently inside the tubing  22 . The tube  40  extends through tube  22  and through an axial passageway extending through first portion  31  and connects to second portion  34 . At the opposite or distal end of the tube  40  it is attached to collar  19 . Accordingly, tube  22  holds one end of the blades  16  and tube  40  is disposed inside tube  22  and attaches to collar  19  which holds the opposite end of the blades  16 . Tube  40  moves independently of tube  22  in the axial direction. When tube  40  is extended in the distal direction it pushes collar  19  away from the end of tube  22 . The resulting force causes the blades  16  to flatten out as shown in FIG. 4. When tube  40  is pulled inward toward the end of tube  22 , the cutting blades  16  expand radially as shown in FIG. 3.  
         [0034]    The first portion  31  and second portion  34  are disposed so that in a first position the second portion  34  cannot be moved away from the first portion  31  in the axial direction. In this configuration, the portions  31 ,  34  are held together so that the blades  16  stay in a set position, and the portions  31 ,  34  may be rotated in unison to operate the cutter  10 . In a second configuration, the first and second portion  31 ,  34  are released by rotating them relative to one another to open a mechanical interlock to allow the second portion  34  to be moved away from the first portion  31  in the axial direction to adjust the position of the blades  16 .  
         [0035]    As shown the first portion  31  carries a shaft  100  with a groove  103  disposed therein, and the second portion  34  has a bore  106  defined therein with a notch  109  extending from the inside wall. The two portions  31 ,  34  are mechanically interlocked by means of the notch  109  on the inner wall on the inside of the second portion  34 . The notch  109  engages with the groove  103  disposed along a portion of the circumference inside the shaft  100  on the first portion  31 . Rotation of the second portion  34  relative to the first portion  31  causes the notch  109  to rotate to a portion of the shaft where the groove no longer obstructs the notch  109 . At this position, the second portion  34  may be moved in the axial direction away from the first portion  31 . Additional grooves may be added so that the second portion can be moved into another position and then rotated back into locking engagement. As a result the blades  16  can be adjusted and then the two portions  31 ,  34  can be locked together. The mechanical interlock between the first and second portions  31 , and  34  is one example of a suitable interlock. The shaft  100  and bore  106  and the notches  109  and grooves  103  can be arranged on the portions  31 ,  34  in numerous-other ways to accomplish the same function as will be obvious to those of ordinary skill in the art. The important point is that the two portions  31 ,  34  are capable of coupling and then uncoupling to allow axial movement of the second portion  34  relative to the first portion  31 . The second portion  34  may be moved axially relative to the first portion  31  and then locked into a new position by means of rotation of the second portion  34  to engage the mechanical interlock.  
         [0036]    In use, the cutter  10  is inserted in the closed position through a lumen. The cutter  10  is passed over the guide wire  13  through the lumen which could be a bile duct. The cutter  10  is threaded through the lumen over the guide wire  13  to arrive at the clogged stent. The cutter  10  is then actuated by rotating the second portion  34  relative to the first portion  31  and then moving the second portion  34  away from the first portion  31  in the axial direction to open the blades  16 . After the blades  16  are opened to the appropriate diameter, the second portion  34  is rotated relative to the first portion  31  to lock the blades into position by means of the cooperating notches  109  and grooves  103 . The cutter  10  is then operated by rotating the blades  16  by means of rotating the handle  26 . The handle may be rotated manually or it may be rotated by an automatic drive (not shown). When the handle  26  is rotated to operate the blades  16 , both portions  31 ,  34  rotate in unison so that the blades  16  do not become twisted.  
         [0037]    The rotating blades  16  remove the ingrown tissue  43  from the inside of the stent. As a result and with minimal trauma, the ingrowth is removed from the stent.  
         [0038]    In the TIPS application, the particles of tissue that are removed by the cutter  10  can be captured by the basket mesh, included in the system and removed through the introducer sheath. It is not necessary to employ a protection mechanism for the biliary stent application because in the biliary application, the fragments and debris will migrate into the bowel loops of the patient without harm.  
         [0039]    While the invention has been described in connection with certain embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.