Abstract:
A catheter is described for use in cannulating a bile duct in ERCP or sphincterotomy procedures. The catheter has a continuous compound curve that has first and second curves. The first and second curves have radii of curvature and lengths that orient the tip of the catheter selectively toward a bile duct.

Description:
RELATED APPLICATIONS 
       [0001]    The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 61/863,591, filed Aug. 8, 2013, which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to an endoscopic device having a continuous compound curve for selective cannulation of the bile duct. 
       BACKGROUND OF THE INVENTION 
       [0003]    Gastrointestinal endoscopy is commonly used to gain access to the digestive tract for the purpose of incising and cauterizing tissue. Many common endoscopy procedures exist for achieving this purpose. 
         [0004]    Endoscopic retrograde cholangiopancreatography (ERCP) is a technique that uses both endoscopy and fluoroscopy for the diagnosis and treatment of medical conditions of the biliary or pancreatic ductal systems such as gallstones, strictures, blocked bile ducts, or the placement of a stent. In an ERCP procedure, a physician employs an endoscope with an ERCP cannula to gain access to the area of the biliary tree. One of the most significant challenges in ERCP is directing a wire guide into the appropriate duct. In bile duct cannulation, the primary concern is to access the bile duct, while avoiding the pancreatic duct due to the potential for post-ERCP pancreatitis. Pancreatitis is the most common complication of ERCP. If a physician has to attempt to cannulate the bile duct multiple times, the risk of pancreatitis increases. 
         [0005]    Endoscopic sphincterotomy is a specific procedure in which a sphincterotome is used in combination with an endoscope to surgically cut a patient&#39;s sphincter. As one example, the sphincterotome may be used to partially cut open the duodenum at the Papilla of Vater to access the common bile duct and remove bile duct stones which form an obstruction therewithin. Conventional sphincterotomes utilized in this technique can create major complications, including bleeding, pancreatitis, perforation, and cholangitis. 
         [0006]    In view of these drawbacks of current technology, there is an unmet need for bile duct cannulas that can controllably and reliably access the bile duct while avoiding the pancreatic duct. 
       SUMMARY OF THE INVENTION 
       [0007]    This invention provides a catheter having a distal end portion with a continuous compound curve in order to assist in cannulation of the bile duct during ERCP procedures or sphincterotomies. The second curve of the compound curve has a more acute angle so that a wire guide may exit the catheter at the proper angle to point towards the bile duct and away from the pancreatic duct. One of the most significant challenges in ERCP is directing the wire guide into the appropriate duct. This invention aims to mitigate some of the challenges associated with cannulation. This compound curved tip may also give a better angle for going through the papilla. 
         [0008]    In one aspect of the invention is provided an endoscopic device for cannulation of a bile duct having a continuous compound curved tip. The device includes a tubular member having a shaft, a distal end portion, and optionally a lumen extending through at least a portion of the tubular member. The distal end portion has a continuous compound curve portion, where the compound curve has a first curved portion and a second curved portion. The first curved portion lies proximal to the second curved portion with the two portions being connected to form a continuous compound curve. The radius of curvature of the first curved portion is greater than the radius of curvature of the second curved portion. In certain embodiments, the first curved portion has a radius of curvature of about 0.7 to about 1.5 inches. In other embodiments, the second curved portion has a radius of curvature of about 0.15 to about 0.5 inches. In certain embodiments, the distal end portion includes a substantially straight end segment. The radii of curvature and the lengths of the first and second curved portions, together, are adapted to position the distal end portion in a patient&#39;s duodenum through the papilla of Vater with the tip of the distal end portion oriented toward the patient&#39;s bile duct and away from the pancreatic duct. 
         [0009]    In one embodiment, the invention provides an ERCP catheter having a distal end portion with a continuous compound curve portion. In another embodiment, the invention provides a sphincterotome having a cutting wire and a distal end portion with a continuous compound curve portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows an exemplary embodiment of an endoscopic device with a distal end having a continuous compound curved tip. 
           [0011]      FIG. 1A  shows an exemplary embodiment of an endoscopic device of the invention having a co-planar arrangement of the shaft  20  and the first curved portion  32  with the curve of the distal end portion shown facing forward in the plane of the device. 
           [0012]      FIG. 1B  shows an exemplary embodiment of an endoscopic device of the invention with the curve of the distal end portion shown facing forward where the first curved portion  32  has a deflection  35  out of the plane of the shaft. 
           [0013]      FIG. 2  is a cross-sectional view of  FIG. 1  taken along line a-a′ showing a wire guide extending through one of the lumens of the sphincterotome and an electrical conductor extending through the other lumen. 
           [0014]      FIG. 3  is a side view of the compound curved tip emerging from an opening at the distal end of an endoscope with the distal tip oriented toward the bile duct. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The embodiments are described with reference to the drawings in which like elements are referred to by like numerals. The relationship and functioning of the various elements of the embodiments are better understood by the following detailed description. However, the embodiments as described below are by way of example only, and the invention is not limited to the embodiments illustrated in the drawings. It should also be understood that the drawings are not to scale and in certain instances details have been omitted, which are not necessary for an understanding of the embodiments, such as conventional details of fabrication and assembly. 
         [0016]    An exemplary embodiment of a curved tip catheter  10  of the invention is shown in  FIG. 1 . The catheter  10  includes a tubular member  12  having a shaft  20  and a distal end portion  30 , which has a continuous compound curve  38 . The continuous compound curve  38  is made up of a first curved portion  32  and a second curved portion  34 . In the embodiment of  FIG. 1 , the distal end portion includes an optional substantially straight end segment  36  and a wire guide  24  extending distally from the distal tip  28 . The catheter also includes a control handle  100 . Optional radiopaque marker bands  26  may be thermally bonded or crimped about the distal end portion to enable fluoroscopic visualization of the distal end portion  30  as it is being maneuvered. The catheter, including the distal end portion, first and second curved portions, and the end segment may be tapered or non-tapered. The walls of the catheter may be of varying thickness. 
         [0017]    In certain embodiments, a wire guide lumen extends through at least a portion of the distal end portion. In general, the tubular member may have a single lumen, or multiple lumens, i.e., two or more lumens.  FIG. 2  shows a cross-sectional view of the tubular member along the line a-a′. In the embodiment in  FIG. 2 , the tubular member has two lumens. Lumen  210  is adapted to receive a wire guide  24 , that may be movably disposed within the wire guide lumen. The lumen  210  may also be configured for the passage of fluids or contrast therethrough. Lumen  170  is adapted to receive an electrical conductor wire  200 . Although the lumens  170  and  210  are shown with circular cross-sectional shapes, other lumen shapes are possible. The tubular member may also have more than two lumens. For example, a third lumen may be dedicated for the passage of fluids or contrast fluid therethrough. 
         [0018]    The electrical conductor wire  200  transmits current to the cutting wire  40 . The conductor wire  200  is a wire extending through lumen  170  ( FIG. 2 ) and is connected at its proximal end to electrical connector  120  ( FIG. 1 ) to provide a high frequency electrical current to conductor  200  and cutting wire  40  as is well known to one of ordinary skill in the art. Conductor  200  protrudes outward of the wall of tubular member  12  at the distal end portion  30  through first opening  41  to become cutting wire  40 . The cutting wire  40  is bowed between the first opening  41  and the second opening  42 , disposed outside of the wall of tubular member  12 , along an inner radius of curvature of the first curved portion  32 . The cutting wire  40  re-enters the wall of the tubular member  12  through second opening  42  and extends proximally through the lumen  170 . The second opening  42  is located proximal to the second curved portion  34 . The cutting wire may have various lengths by changing the proximal and distal openings  41  and  42 . 
         [0019]    Preferably, the conductor  200  and cutting wire  40  may be formed from a single wire. Alternatively, the cutting wire  40  and conductor  200  may be distinct components that may be connected to each other by soldering or other conventional means known in the art. 
         [0020]    The compound curved tip catheter of the invention may be made from various materials including polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), or other thermoplastic resins (e.g., polyurethane). Preferably the second curved portion, the compound curve portion and the catheter are made from PTFE. Where the compound curve portion is made from FEP, the curved tip may also be affixed to a catheter shaft made of PTFE using a standard heat bond. 
         [0021]    The compound curved tip may be formed in two steps. In the first step, the second curved portion is formed by heat setting, for example using a die or mandrel. Following insertion into a die or mandrel, suitable heat and pressure may be applied for a given duration of time to heat set the second curved portion. In general, the second curved portion is formed by heating to a temperature sufficient for it to acquire the shape of the die/mandrel and retain that shape upon cooling. For example, the second curved portion may be formed with PTFE by heat setting at a temperature sufficient to soften the PTFE (e.g., around the melting temperature). The second curved portion formed in this manner permanently retains the curved form imparted by the heat setting process. In the second step of forming the compound curved tip, the first curved portion is formed using a conventional forming/shaping wire, as is well known in the art. 
         [0022]    The first and second curved portions of the continuous compound curve have different center points and angles. The first curved portion has a larger radius of curvature than the second curved portion. In one aspect of the invention, the first curved portion has a radius of curvature of about 0.7 inch to about 1.5 inches and the second curved portion has a radius of curvature of about 0.15 to about 0.5 inch. The radii of curvature and the lengths of the first and second curved portions, together, are adapted to orient the distal tip of the distal end portion toward a bile duct and away from a pancreatic duct. In one embodiment of this aspect, the first curved portion has a length of about 1.5 inches to about 4.5 inches. In another embodiment, the second curved portion has a length of about 0.1 to about 0.35 inch. In another embodiment, the first curved portion has a radius of curvature of about 1 inch and a length of about 2.1 inches. In yet another embodiment, the second curved portion has a radius of curvature of about 0.25 inch and a length of about 0.13 inch. 
         [0023]    According to any of the foregoing embodiments are still other embodiments where the radius of curvature and the length of the second curved portion form an arc of about 5 to about 60 degrees. In still other embodiments, the radius of curvature and the length of the second curved portion  34  form an arc of about about 30 degrees. 
         [0024]    The substantially straight end segment  36  extends beyond the second curved portion. The combined length of the substantially straight end segment and the second curved portion is about 0.15 to about 0.35 inch. Thus, the length of the substantially straight end portion may have any length up to about 0.25 inch. In one embodiment, the substantially straight end segment has a length of about 0.05 inch. 
         [0025]    The invention encompasses various combinations among the curvatures and lengths given above for the first curved portion, the second curved portion, and the substantially straight end segment. For example, in one embodiment, the first curved portion has a radius of curvature of about 0.7 inch to about 1.5 inches and a length of about 1.5 to about 4.5 inches and the second curved portion has a radius of curvature of about 0.15 to about 0.5 inch and a length of about 0.1 to about 0.35 inch. In another embodiment, the first curved portion has a radius of curvature of about 1 inch and a length of about 2.1 inches and the second curved portion has a radius of curvature of about 0.15 to about 0.5 inch and a length of about 0.1 to about 0.35 inch. In another embodiment, the first curved portion has a radius of curvature of about 0.7 inch to about 1.5 inches and a length of about 1.5 to about 4.5 inches and the second curved portion has a radius of curvature of about 0.25 inch and a length of about 0.13 inch. In yet another embodiment, the first curved portion has a radius of curvature of about 1 inch and a length of about 2.1 inches and the second curved portion has a radius of curvature of about 0.25 inch and a length of about 0.13 inch. 
         [0026]    The first curved portion and the second curved portion may be substantially co-planar or they may be oriented in different planes according to the needs of a particular medical procedure. Similarly, the first curved portion  32  may be substantially planar with the shaft as illustrated in  FIG. 1A . Alternatively, as shown in  FIG. 1B , the first curved portion may include a deflection  35  out of the plane formed by the shaft and any section of the first curved portion that is co-planar with the shaft. This arrangement gives the first curved portion a three-dimensional shape. The deflection may be a continuous deflection throughout the length of the first curved portion giving the first curved portion a spiral or partial spiral shape. Or, the first curved portion may have a single deflection with the more distal section of the first curved portion being substantially in one plane defined by the single deflection. Where the first curved portion includes a deflection out of the plane of the shaft, the distal tip may be deflected out of the plane formed by the shaft and any co-planar section of the first curved portion by any angle up to about 40-45 degrees. Thus, in this arrangement the distal tip, the first curved portion, and the shaft do not substantially occupy a single plane. Where the first curved portion has a three dimensional curve, the angle of deflection at the distal tip is preferably about 27 degrees. Throughout the deflection in the first curved portion, the radius of curvature of the first curved portion, as described herein, remains substantially unchanged. 
         [0027]    In each of the embodiments described above, the first curved portion is adapted to deform from the stated radius of curvature when subjected to a straightening force. Upon removal of the straightening force, the first curved portion may return to its original curved form. 
         [0028]    As illustrated in  FIG. 3 , an endoscope  50  is first positioned within a patient&#39;s duodenum  90  with the distal end of the endoscope near the duodenal papilla  80 . The distal end portion of the tubular member is advanced within an accessory channel  52  of an endoscope  50 . During advancement within the accessory channel, the first curved portion flexes into a semi-straightened shape. As the distal end portion emerges from the distal end of the accessory channel, it relaxes back to its pre-curved shape. The distal end portion is shown in  FIG. 3  advanced through the duodenal papilla  80  with the second curved portion  32  orienting the tip of the catheter toward the bile duct  60  and away from the pancreatic duct  70 . The selective orientation of the catheter tip toward the bile duct permits a wire guide to exit the tip of the catheter at an angle pointing toward the bile duct. 
         [0029]    The second curved portion provides a better angle for selective cannulation of the bile duct compared to catheters lacking a continuous compound curve. This permits a physician to more readily cannulate the bile duct with fewer attempts, thereby cutting down on procedure time and repeated attempts to cannulate the bile duct that have been linked to pancreatitis. 
         [0030]    The above figures and disclosure are intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in the art. All such variations and alternatives are intended to be encompassed within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the attached claims.