Abstract:
The present invention relates to a medical device, for pancreas, equipped with drainage feature. The medical device includes a stent having an exterior surface, a proximal end and a distal end. The medical device further includes a drainage tube helically wrapped around the stent. The drainage tube includes an external surface, an internal surface, a proximal end, and a distal end. The external surface of the drainage tube is designed with a plurality of holes. The pluralities of holes are connected to the internal surface via a lumen. The plurality of holes can be configured to direct the fluid from side walls of pancreas and bring it out through lumen to avoid occlusion of the side walls in pancreas.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Application No. 61/779,848, filed Mar. 13, 2013, the entire contents of which are herein incorporated by reference. 
     
    
     FIELD 
       [0002]    The present invention relates to bodily fluid drainage, more particularly, to a pancreatic stent drainage system. 
       BACKGROUND 
       [0003]    Pancreatic endotherapy has been used for years for treatment of several types of pancreatic disorders including but not limited to chronic pancreatitis, idiopathic acute recurrent pancreatitis, and many such others. 
         [0004]    Normally, inside the human body the pancreas is connected to the duodenum via the pancreatic duct. The pancreatic duct abuts the sphincter of Oddi, which connects the pancreatic duct to the duodenum. The pancreatic duct delivers to the duodenum pancreatic fluids required for metabolism. In various pancreatic disorders, pancreatic tissues may swell or increase abnormally thereby constricting the pancreatic duct and obstructing flow of pancreatic fluids into the duodenum. Such obstructions could lead to various complications including those arising from the accumulation of pancreatic fluids inside the pancreatic tissue or the pancreatic duct. In such cases, an intraluminary prosthesis, such as a stent, may be used for treatment of the obstructed pancreatic duct. The stent provides an outwardly-directed radial force that opens the constriction of the pancreatic duct thereby allowing pancreatic fluid to flow into the duodenum. In some cases, at least a portion of the stent is placed proximal to the sphincter of Oddi and adjacent to ampulla of Vater near and inside head region of the pancreas in a patient&#39;s body. 
         [0005]    Intraluminal stents within the pancreatic duct are associated with several drawbacks including stent migration and blockage of side branches of the pancreatic duct. Blockage of pancreatic duct side branches can impede flow of pancreatic fluids and result in chronic pancreatitis. Some pancreatic stents are polymer tubes that have side holes helically placed along a length of the stent. The side holes allow pancreatic fluid to flow into the lumen of the stent thereby reducing the incidence of side branch occlusion while still allowing for stent removal at a future time. An example of a intraluminal pancreatic stent is provided in U.S. Pat. No. 6,132,471, which is incorporated herein by reference. 
         [0006]    Recently physicians are looking to metal stents for use in the pancreas. Expandable metal stents provide substantially consistent outward radial force over time, which allows the stent to expand as duct constriction is relieved. In this way, metal stents avoid the need to exchange the stents multiple times, each time for a progressively larger diameter stent, until the desired dilation of the pancreatic duct is achieved. Another benefit of metal stents is a greater patency rate. 
         [0007]    A concern with metal stents is that surrounding tissue may grow into the stent, complicating stent removal and compromising the stent lumen. For this reason metal stents are often coated with a polymeric covering that reduces growth of host tissue into the interstices of the metal stent. Coated metal stents allow for easier and less traumatic stent removal. Unfortunately, coated stents are more susceptible to stent migration, which can result in the stent exiting the treatment site. 
         [0008]    Coated stents are also more likely to occlude pancreatic fluid flow within side branches of the pancreatic duct. Pancreatic fluid flows to the duodenum through a network of branching upstream ducts that converge into a central pancreatic duct. Coated stents placed in a downstream pancreatic duct may block the mouth of an upstream tributary duct that empties into the downstream duct. In this way, a coated stent could dam an upstream network of ducts. Impeding the flow of pancreatic fluid can harm the pancreas and result in pancreatitis. 
         [0009]    Thus, there exists a need for a stent with an additional drainage system to avoid occlusion of upstream ducts while reducing the likelihood of stent migration. 
         [0010]    Without limiting the scope of the invention, a brief summary of some of the claimed embodiments of the invention is provided below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention can be found in the detailed description of the invention. 
         [0011]    A brief abstract of the technical disclosure in the specification is provided as well for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims. 
         [0012]    All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. 
       SUMMARY 
       [0013]    In at least one embodiment, the present invention relates to a medical device equipped with a drainage feature. The medical device includes a stent having an outer surface, a proximal end, and a distal end. The medical device further includes a drainage tube. The drainage tube includes an internal surface, an external surface, a distal end, and a proximal end. In an embodiment, the drainage tube is configured to be attached to the outer surface of the stent. The medical device is configured such that the proximal end of the drainage tube is positioned adjacent to the proximal end of the stent. Further, the external surface of the drainage tube is configured to include a plurality of holes. The holes on the outer surface of the drainage tube are connected to the internal surface of the drainage tube. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0014]    The invention and the following detailed description of certain embodiments thereof can be understood with reference to the following figures: 
           [0015]      FIG. 1A  is an anatomical view of the inventive medical device operationally positioned in a body of a patient. 
           [0016]      FIG. 1B  is an enlarged view of the medical device in  FIG. 1A  positioned in the body of the patient. 
           [0017]      FIG. 2  is a perspective view of an embodiment of the inventive medical device comprising a stent and a drainage tube. 
           [0018]      FIG. 3  is a perspective view of an embodiment of the inventive medical device comprising a stent, a drainage tube, and a covering disposed on the outer surface of the stent. 
           [0019]      FIG. 4A  is a perspective view of an embodiment of the inventive medical device comprising a stent, a drainage tube, and a covering disposed on an inner surface of the stent. 
           [0020]      FIG. 4B  is an end view of the drainage tube of  FIG. 4A . 
           [0021]      FIG. 5A  is a perspective view of a portion of an embodiment of a drainage tube with a circular cross-section. 
           [0022]      FIG. 5B  is an end view of the drainage tube of  FIG. 5A . 
           [0023]      FIG. 6A  is a perspective view of a portion of an embodiment of a drainage tube with an oval cross-section. 
           [0024]      FIG. 6B  is an end view of the drainage tube of  FIG. 6A . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    While this invention can be embodied in many different forms, specific embodiments of the invention are described in detail herein. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
         [0026]    The invention can be used in humans and used in non-human animals. This invention is suitable for use in the pancreas and for use in other organs and tissues. Although, illustrated embodiments refer to a stent being placed in the pancreatic duct, the inventive medical device can be used for performing a medical procedure in any body passageway including but not limited to gastrointestinal tract, the biliary tract, the urinary tract, the respiratory tract, the arteries and veins. Those skilled in the pertinent art will recognize that the use of the inventive medical device as described herein is not limited to the pancreas, but can be used in vascular conduits and other ductal systems such as a bile duct, a urinary tract, and the like in the human body. One aspect of the inventive medical device is to expand or open a passageway to allow flow of materials or air inside the body of a patient 
         [0027]    Various aspects of the invention are depicted in the figures. For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated. 
         [0028]    As used in the specification, the terms proximal and distal should be understood as being in terms of a physician delivering the medical device to a patient. The term “proximal” refers to an area or portion of the medical device or patient that is closest to the physician during a placement procedure. The term “distal” refers to an area or portion that is farthest from the physician. 
         [0029]      FIG. 1A  is an anatomical elevational view of a pancreas  1 , duodenum  2 , gall bladder  3 , and adjacent portions of the alimentary canal. In one embodiment, the inventive medical device  100  is used to treat a narrowing or constriction of the pancreatic duct  4 . The site of treatment is herein referred to as the target site  110 . 
         [0030]      FIG. 1B  shows an enlarged view of the region where pancreatic duct  4  abuts duodenum  2 . In at least one embodiment, medical device  100  is delivered to target site  110  by an endoscopic delivery catheter  102  that has been advanced from the esophagus (not shown) into duodenum  2 . In some embodiments, medical device  100  is implanted using a delivery catheter  102  having a guide wire  104  that aids in placement of medical device  100 . Guide wire  104  is advanced past the sphincter of Oddi  5  and along the pancreatic duct  4  to reach target site  110 . Medical device  100  is shuttled from delivery catheter  102  along guide wire  104  to target site  110 . In at least one embodiment, an introducer catheter (not shown) maintains medical device  100  in an unexpanded conformation and delivers unexpanded medical device  100  to target site  110 . Once medical device  100  is properly positioned adjacent target site  110 , medical device  100  is radially expanded so as to support and reinforce the vessel at target site  110 . In some embodiments, medical device  100  is self-expanding and will radially expand once deployed. In some embodiments, the introducer catheter comprises an outer sheath that keeps medical device  100  in an unexpanded conformation. Once the introducer catheter reaches target site  110 , the outer sheath of the introducer catheter is retracted, allowing medical device  100  to expand and engage the lumen wall of target site  110 . In some embodiments, radial expansion of medical device  100  is accomplished by inflation of a balloon (not shown) attached to the introducer catheter. 
         [0031]      FIG. 2  is a perspective view of one embodiment of inventive medical device  100 , wherein a drainage tube  204  wraps around at least a portion of the outer surface  220  of a stent  202 . In some embodiments, drainage tube  204  is of similar design to a 3 French plastic stent made of a polyethylene material. 
         [0032]    An outer surface  220  of stent  202  defines an outer diameter  224  of stent  202 . An inner surface  222  of stent  202  defines a lumen  226  of stent  202 . Stent  202  has a proximal end  230 , a distal end  234 , and a central region  232  located between proximal end  230  and distal end  234 . Central region  232  has a mid-plane  233 , which is equidistant from proximal end  230  and distal end  234 . Stent  202  has a proximal region  231  and a distal region  235 , wherein proximal region  231  is the region of stent  202  located between mid-plane  233  and proximal end  230 , and distal region  235  is the region of stent  202  located between mid-plane  233  and distal end  234 . In some embodiments, stent  202  is flared at at least one end so that outer diameter  224  in central region  232  is smaller compared to outer diameter  224  at proximal end  230  and/or distal end  234 . Proximal flare  254  and distal flare  252  increase the anti-migratory ability of stent  202 , thereby facilitating stent fixation. Proximal flare  254  resists migration of stent  202  in the proximal direction. Similarly, distal flare  252  resists migration of stent  202  in the distal direction. In some embodiments, proximal flare  254  and the distal flare  252  are constructed to readily conform to changes in body lumen walls during transmittal of bodily fluids or food. In some embodiments, stent  202  is self expanding and able to conform to changes in the body lumen walls thereby mitigating the need to replace stent  202  with another stent having a larger outer diameter  224 . 
         [0033]    In some embodiments, distal end  244  of drainage tube  204  is located at base  250  of distal flare  252 , wherein base  250  of distal flare  252  is the portion of the distal flare  252  that is contiguous with central region  232  of stent  202 . In some embodiments, stent  202  facilitates treatment of blockages present in the pancreatic duct. In at least one embodiment, stent  202  can be placed so that the proximal end  230  of stent  202  is proximate the ampulla of Vater so that the pancreatic fluid from the pancreatic duct can unite with the bile juices to form a mixture, which proceeds toward the sphincter of Oddi  5  and into the duodenum  2  to facilitate digestion of food. In at least one embodiment, proximal end  240  of drainage tube  204  is positioned adjacent to proximal end  230  of stent  202 , allowing proximal end  240  of drainage tube  204  to empty into the duodenum when proximal end  230  of stent  202  is positioned proximal to the sphincter of Oddi  5 . In some embodiments, stent  202  includes radiopaque markers made of gold or any other radiopaque material suitable for implantation. The radiopaque markers aid fluoroscopic imaging of stent  202  during placement of stent  202 . In some embodiments, the radiopaque markers are incorporated at the proximal flare  254  and/or the distal flare  252  of stent  202 . 
         [0034]    In some embodiments, stent  202  is flexible and elastomeric in nature, allowing stent  202  to be radially compressed for intraluminary catheter implantation. Stent  202  can be any type of expandable stent, such as laser cut or braided designs. In some embodiments, outer surface  220  of stent  202  has a substantially uneven structure. The uneven structure increases the amount of frictional force between the body lumen walls and the outer surface  220  of the stent  202  thereby increasing anti-migratory properties of stent  202 . In at least one embodiment, stent  202  is cylindrical. In some embodiments, stent  202  has an annular transverse cross-section. The transverse cross-section of stent  202  may be circular or non-circular, having a uniform bore or non-uniform bore. 
         [0035]    Stent  202  or portions thereof can be metal, including but not limited to shape memory metal such as nitinol. Stent  202  and drainage tube  204  or portions thereof can be fabricated using shape memory polymers, or simple elastic medical-grade polymers, or medical-grade plastically expandable materials. Examples of some suitable materials include but are not limited to expanded polytetrafluoroethylene (ePTFE), polytetrafluoroethylene which is not expanded, polyurethane olefin polymers, polyethylene, polypropylene, polyvinyl, polyvinyl chloride, fluorinated ethylene propylene copolymer, polyvinyl acetate, polystyrene, polyethylene terephthalate (PET) polyesters, naphthalene dicarboxylate derivatives, such as polyethylene naphthalate, polybutylene naphthalate, poly trimethylene naphthalate and trimethylenediol naphthalate, polyurethane, polyurea, silicone rubbers, polyamides, polycarbonates, polyaldehydes, natural rubbers, polyester copolymers, styrene-butadiene copolymers, polyethers, such as fully or partially halogenated polyethers, copolymers, polyesters, including, polyolefins, polymethyl acetates, polyamides, naphthalane dicarboxylene derivatives, natural silk, and combinations thereof. Stent  202  and drainage tube  204  can be made from biodegradable or bioabsorbable materials. Stent  202  can be formed of biocompatible materials, such as polymers which may include fillers such as metals, carbon fibers, glass fibers or ceramics. 
         [0036]    Drainage tube  204  has an external surface  212  and an internal surface  214 , which defines a lumen  216  of drainage tube  204 . Drainage tube  204  has an intermediate portion  242 , which connects proximal end  240  to distal end  244 . Drainage tube  204  includes a plurality of drainage holes  260 , which connect external surface  212  to internal surface  214 . In some embodiments, drainage holes  260  are fabricated along at least a portion of intermediate portion  242 . Drainage holes  260  facilitate flow of pancreatic fluid to the duodenum  2  by providing a pathway for the pancreatic fluid to access lumen  216  of drainage tube  204 . 
         [0037]    In at least one embodiment, drainage tube  204  wraps around stent  202  so that proximal end  240  of drainage tube  204  is positioned adjacent to the proximal end  230  of stent  202 . In some embodiments, drainage tube  204  wraps around only a portion of stent  202 . For example, in at least one embodiment drainage tube  204  wraps around stent  202  from the proximal end  230  of stent  202  to mid-plane  233  of stent  202  so that distal end  244  of the drainage tube  204  is adjacent to mid-plane  233  of stent  202 . In some embodiments, distal end  244  of drainage tube  204  lies distal of mid-plane  233  of stent  202 . In some embodiments, distal end  244  of drainage tube  204  lies proximal of mid-plane  233  of stent  202 . In some embodiments, drainage tube  204  wraps around the entire length of stent  202  so that proximal end  240  of drainage tube  204  is adjacent to proximal end  230  of stent  202 , and distal end  244  of drainage tube  204  is adjacent to distal end  234  of stent  202 . 
         [0038]    In some embodiments, drainage tube  204  wraps helically around outer surface  220  of stent  202 . External surface  212  of drainage tube  204  includes two portions—a first portion  217  that is in contact with a body lumen wall, and a second portion  219  that is in contact with outer surface  220  of stent  202 . In at least one embodiment, second portion  219  of drainage tube  204  is secured to outer surface  220  of stent  202  at one or more discrete points of contact between drainage tube  204  and outer surface  220 , allowing drainage tube  204  to slide along and maintain contact with outer surface  220  as stent  202  radially expands. In at least one embodiment, drainage tube  204  is secured to outer surface  220  by at least one of an adhesive coupling, thermal coupling, and mechanical coupling. 
         [0039]    In some embodiments, first portion  217  includes a plurality of drainage holes  260  while second portion  219  does not contain any drainage holes  260 . Placement of drainage holes  260  on external surface  212  is defined by an angular coordinate that is referenced to a polar coordinate system located centrally within lumen  216  of drainage tube  204 . Such a coordinate system is shown in  FIGS. 5B and 6B . In the reference coordinate system, an angle of 0° refers to the mid-line of second portion  219 . Placement of drainage holes  260  is also defined by a longitudinal coordinate that specifies the distance of travel along drainage tube  204  from proximal end  240 . In at least one embodiment, all drainage holes  260  have the same angular coordinate. In some embodiments, at least two drainage holes  260  have different angular coordinates. In some embodiments, two or more drainage holes  260  have the same longitudinal coordinate and a different angular coordinate. In some embodiments, drainage holes  260  are uniformly spaced along the longitudinal coordinate direction. In some embodiments, drainage holes  260  are non-uniformly spaced along the longitudinal coordinate direction. 
         [0040]    External surface  212  of drainage tube  204  defines a transverse cross-sectional shape. The transverse cross-sectional shape of drainage tube  204  can be any geometry that can be extruded or molded and allow fluid to pass without creating permanent anchoring points of pancreatic tissue. In some embodiments, external surface  212  defines a circular transverse cross-sectional shape. In at least one embodiment, external surface  212  defines a transverse cross-sectional shape that is an oval. In some embodiments, drainage tube  204  has a variable internal and/or external diameter. In at least one embodiment, drainage tube  204  has a uniform lumen  216  and a uniform transverse cross-sectional shape. In some embodiments, lumen  216  is non-uniform. In at least one embodiment, the diameter of lumen  216  is smaller in the distal region of drainage tube  204  compared with the diameter of lumen  216  in the proximal region of drainage tube  204 . 
         [0041]    Drainage holes  260  have a width  262 . In at least one embodiment, all drainage holes  260  have the same width  262 . In some embodiments, at least two drainage holes  260  have different widths  262  from one another. In some embodiments, width  262  of each drainage hole  260  varies from 0.005 inches to 0.015 inches. In at least one embodiment, width  262  is 0.010 inches. In some embodiments, drainage holes  260  are oval shaped or circular. In some embodiments, drainage holes  260  are different shapes other than the circular shape or oval shape. For example, in some embodiments drainage holes  260  have an elliptical shape or a polygonal shape, such as a square or a rectangular cross-sectional shape. In some embodiments, all drainage holes  260  have the same shape. In some embodiments, at least two drainage holes  260  have different shapes from one another. In at least one embodiment, the shape of drainage hole  260  tapers as drainage tube  204  is traversed. For example, in at least one embodiment all drainage holes  260  are circular with the width  262  of the drainage holes  260  decreasing as the drainage tube  204  is traversed in the distal direction. 
         [0042]      FIG. 3  is a perspective view of the inventive medical device  100 , in accordance with an embodiment of the invention. In some embodiments, medical device  100  includes a covering  302  attached to stent  202 . In some embodiments, covering  302  is disposed on outer surface  220  of stent  202 . In some embodiments, covering  302  is an integral part of outer surface  220  of stent  202 . In some embodiments, covering  302  extends over the entire central region  232  of the stent  202 . In some embodiments, covering  302  extends over some but not all of central region  232 . In at least one embodiment, outer surface  220  of stent  202  is free from covering  302  at proximal flare  254  and distal flare  252  to preserve the anti-migratory ability of stent  202 . In some embodiments, covering  302  is disposed on outer surface  220  of stent  202  at proximal flare  254  and distal flare  252 . 
         [0043]    In some embodiments, covering  302  is disposed on inner surface  222  of stent  202 .  FIG. 4A  is a perspective view of one embodiment of medical device  100  having a covering  302  disposed on inner surface  222  of stent  202 .  FIG. 4B  is an end view of the embodiment of medical device  100  depicted in  FIG. 4A . In some embodiments, covering  302  is attached to inner surface  222  of stent  202 . In at least one embodiment, covering  302  is an integral part of inner surface  222  of stent  202 . In some embodiments, covering  302  extends over the entire central region  232  of stent  202 . In some embodiments, covering  302  extends over some but not all of central region  232 . In at least one embodiment, covering  302  is disposed on inner surface  220  of stent  202  at proximal flare  254  and distal flare  252 . In some embodiments, inner surface  220  of stent  202  is free from covering  302  at proximal flare  254  and distal flare  252 . 
         [0044]    In some embodiments, covering  302  is made of a material selected from the group consisting of silicone, urethane, biocompatible materials, and combinations thereof. In some embodiments, covering  302  is made of polytetrafluoroethylene (PTFE). 
         [0045]    In some embodiments, covering  302  makes stent  202  less susceptible to invasion from surrounding tissue. In at least one embodiment, covering  302  increases patency by reducing the area of stent  202  that is available as a scaffold for accumulation of undesired substances that lead to occlusion. Few exemplary situations leading to occlusion include but are not limited to sludge formation, tumor overgrowth, tumor ingrowth, food debris, or stone formation. 
         [0046]      FIG. 5A  is a perspective view of one embodiment of drainage tube  204  that has a circular cross-section.  FIG. 5B  is an end view of the drainage tube  204  of  FIG. 5A . 
         [0047]      FIG. 6A  is a perspective view of one embodiment of drainage tube  204  that has an oval cross-section.  FIG. 6B  is an end view of the drainage tube  204  of  FIG. 6A . The oval geometry can be configured to minimize the overall profile of the stent  202  and still provide a passage for the pancreatic fluid. The oval geometry of the transverse cross-section can be helpful in mechanical traction to prevent migration. In some embodiments, the transverse cross section of external surface  212  of drainage tube  204  can be of a different shape other than the circular-shape or the oval-shape. For example, the cross-sectional shape of drainage tube  204  can be an elliptical shape or polygon shape, such as a square or a rectangular cross-sectional shape. 
         [0048]    A description of some exemplary embodiments of the invention can be contained in the following numbered paragraphs: 
         [0049]    1. A medical device equipped with a drainage feature, the device comprising: 
         [0050]    a stent having a proximal end, a distal end, and an outer surface; and 
         [0051]    a drainage tube having a proximal end, a distal end, an internal surface, and an external surface, the external surface having a plurality of drainage holes, the drainage holes connecting to the internal surface, the drainage tube being attached to the outer surface of the stent. 
         [0052]    2. The medical device of claim  1  wherein the proximal end of the drainage tube is positioned adjacent to the proximal end of the stent. 
         [0053]    3. The device of claim  1  wherein the drainage tube wraps around the outer surface of the stent. 
         [0054]    4. The device of claim  3  wherein the drainage tube helically wraps around the outer surface of the stent. 
         [0055]    5. The device of claim  1  wherein the external surface of the drainage tube has a transverse cross section which is oval-shaped. 
         [0056]    6. The device of claim  1  wherein the external surface of the drainage tube has a transverse cross section which is circular. 
         [0057]    7. The device of claim  1  wherein internal surface of the drainage tube has a length and a transverse cross section, the transverse cross section varying in size along the length of the drainage tube. 
         [0058]    8. The device of claim  1  wherein at least one of the distal and proximal ends of the stent is flared. 
         [0059]    9. The device of claim  1  wherein at least a portion of the stent is made of a material selected from a group consisting of metals, polymeric materials, biodegradable materials, bioabsorbable materials, and combinations thereof. 
         [0060]    10. The device of claim  1  wherein at least a portion of the drainage tube is made of a material selected from a group consisting of polymeric materials, biodegradable materials, bioabsorbable materials, and combinations thereof. 
         [0061]    11. The device of claim  1  wherein each of the plurality of holes has a diameter of about 0.010 inch. 
         [0062]    12. The device of claim  1  wherein at least one of the plurality of holes is oval-shaped. 
         [0063]    13. The device of claim  1  wherein the plurality of holes vary in size and shape. 
         [0064]    14. The device of claim  1  wherein the stent further comprises a covering, the covering surrounding the outer surface of the stent and being made of a material selected from a group consisting of silicone, urethane, biocompatible materials, and combinations thereof. 
         [0065]    15. The medical device of claim  1 , wherein the stent is of a braided type. 
         [0066]    16. The medical device of claim  1 , wherein the drainage tube is secured over the external surface of the stent by at least one of an adhesive coupling, thermal coupling, and mechanical coupling. 
         [0067]    17. The medical device of claim  1 , wherein the drainage tube includes a first portion exposed to a body lumen wall and a second portion in contact with the stent, wherein the plurality of holes are provided along at least a portion of the drainage tube such that the plurality of holes stay at the first portion and are exposed to the body lumen wall. 
         [0068]    This completes the description of the invention. Those skilled in the art can recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.