Abstract:
A ureteral bypass device and procedure suitable for performing internal urinary diversions within patients, including patients such as humans and veterinary animals (cats and dogs). The device includes a nephrostomy catheter having a proximal end, an oppositely-disposed distal end, and means for securing the distal end within the renal pelvis of a kidney of a patient, a cystostomy catheter having a proximal end, an oppositely-disposed distal end, and means for securing the distal end of the cystostomy catheter within the urinary bladder of the patient, and an adaptor fluidically connected to the proximal ends of the nephrostomy and cystostomy catheters so as to fluidically connect the nephrostomy and cystostomy catheters together through the adaptor. If implanted subcutaneously, the adaptor may include an entry site that has a self-sealing septum that can be accessed with a needle while the device remains implanted and secured under the skin to subcutaneous tissue.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/423,285, filed Dec. 15, 2010, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to devices and procedures suitable for treating patients having ureteral obstructions or the like. More particularly, this invention relates to a ureteral bypass device and procedures for implanting the device, for example, by placing the device under the skin (subcutaneously) or within the abdominal cavity (intra-abdominally) of a patient. The device utilizes catheters and locking/retention mechanisms adapted to retain distal ends of the catheters within the renal pelvis and urinary bladder to avoid inadvertent dislodgement, as well as provide a seal to the kidney and bladder tissues to prevent urine leakage after device placement. The device further includes a port adapted to enable sampling, flushing, and testing the entire device for diagnostic or therapeutic purposes, without the need for invasive and expensive diagnostic methods. 
     Ureteral obstructions are a major surgical and endourological problem in both human and veterinary medicine. These obstructions can occur for various reasons, the most common of which include but are not limited to ureterolithiasis, urinary tract (intrinsic) or extrinsic neoplasia, and ureteral strictures. The traditional treatment in human medicine has involved the use of minimally invasive endourological procedures, for example, ureteral stenting, lithotripsy, ureteroscopic laser ablation, laparoscopic ureteral resection and anastomosis, and ureteropyelotomy. Minimally invasive treatments have nearly replaced open surgical procedures. In contrast, open surgical procedures such as ureterotomy, ureteral reimplantation and ureteronephrectomy are routinely performed for most causes of ureteral obstructions in companion animals (for example, canine and feline) due to the small nature of the canine (about 1 to 2 mm) and feline (about 0.3 to 0.4 mm) ureter and the minimal options available for interventional devices in animals of this size. Recently, the development of feline and canine double-pigtail ureteral stents has occurred and interventional treatments have become progressively more available. Unfortunately situations arise, particularly in small pediatric and veterinary patients, in whom ureteral decompression is necessary but traditional surgery or endourological procedures are associated with excessive morbidity or mortality, are impossible due to the size or anatomy, or are contraindicated. 
     In human medicine, if diversion procedures fail, implantation of an externalized percutaneous nephrostomy tube is usually necessary to provide either temporary or long-term drainage of the renal collection system. Placement of an externalized percutaneous nephrostomy tube is also possible in veterinary and pediatric patients for in-hospital stabilization, but is not feasible for long-term use. Major disadvantages associated with long-term use include the need for regular exchanges, the risk of urinary tract infections, urinary leakage and catheter dislodgement, social embarrassment, and an impaired quality of life reported for patients. Subcutaneous (or intra-abdominal) urinary diversion devices can internalize a nephrostomy catheter and allow the urine to drain to the urinary bladder through a subcutaneous tunnel. This eliminates most of the major disadvantages associated with externalized nephrostomy catheters because infection, regular nursing care, leakage, dislodgement, and an impaired quality of life are no longer prominent issues. Subcutaneous (or intra-abdominal) urinary diversion (bypass) devices become a more useful solution to very complicated medical problems associated with veterinary and pediatric patients, for whom externalized catheters are not a realistic option outside of a hospital setting. 
     A few variations on ureteral bypass devices have been reported in the past, varying from non-locking pigtail catheters, non-fenestrated double-pigtail stents, and non-locking double-lumen catheters with an inner silicone tube and an outer polyester sheath. For example, such devices have been reported or offered by Coloplast A/S. These various devices have been placed with surgical approaches requiring suturing of the tube to the bladder wall and renal capsule to prevent dislodgement and leakage. Short-term and long-term complications have been reported, with the major concerns being dislodgement, occlusion (encrustation), and difficulty in placement. However these devices still remain promising when all other traditional options have failed. 
     It is clear that there is an ongoing need for devices that are capable of treating various causes of ureteral obstruction, regardless of etiology, patient species, or size, in a rapid, simple, and safe manner. In particular, there is a need for a ureteral bypass device capable of overcoming the shortcomings of the prior art, particularly, dislodgement, discomfort, the currently invasive placement of the device, the large size of the device, as well as the concern for occlusion or encrustation of the device. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides a ureteral bypass device and procedure suitable for performing internalized urinary diversions within patients, including large patients such as human adults, as well as small patients such as children and animals. 
     According to a first aspect of the invention, the procedure includes creating an incision in the skin of a patient, implanting a nephrostomy catheter through the incision and securing a distal end of the nephrostomy catheter within the renal pelvis of a patient, implanting a cystostomy catheter through the incision and securing a distal end of the cystostomy catheter within the urinary bladder of the patient, fluidically connecting proximal ends of the nephrostomy and cystostomy catheters to a shunting port, and then subcutaneously implanting the shunting port to yield a subcutaneous ureteral bypass device, in which the nephrostomy and cystostomy catheters are fluidically connected together. The incision is then closed. The shunting port has a self-sealing septum that defines an entry site of the shunting port and is accessible through the skin of the patient to provide means for performing diagnostic and therapeutic procedures. 
     According to a second aspect of the invention, a ureteral bypass device includes a nephrostomy catheter having a proximal end, an oppositely-disposed distal end, and means for securing the distal end within the renal pelvis of a kidney of a patient, a cystostomy catheter having a proximal end, an oppositely-disposed distal end, and means for securing the distal end of the cystostomy catheter within the urinary bladder of the patient, and an adaptor fluidically connected to the proximal ends of the nephrostomy and cystostomy catheters so as to fluidically connect the nephrostomy and cystostomy catheters together through the port. The adaptor may be a shunting port that includes a self-sealing septum that provides an entry site for the port. 
     Another aspect of the invention is a procedure for performing an internal urinary diversion using a ureteral bypass device comprising the elements described above. 
     A technical effect of the invention is that the device is capable of use in the treatment of many, if not all, causes of ureteral obstruction, regardless of etiology, patient size or species. If the device includes a shunting port with an entry site, the entry site is preferably configured to provide access to the port that allows for testing, sampling and flushing of the device, and therefore enables occlusions, encrustation, and the like to be cleared or avoided without necessitating the removal of the device from the patient or the need for future surgical manipulation. The device is well suited for remaining indwelling long-term within a patient, preferably for periods of at least 36 months. In young children with anatomical anomalies, this allows the time for the urinary system to grow prior to the consideration of more dramatic reconstructive surgeries that would ideally be done at an older age. 
     Other aspects and advantages of this invention will be better appreciated from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a ureteral bypass device in accordance with an embodiment of this invention. 
         FIG. 2  is a perspective view of components of the ureteral bypass device of  FIG. 1 . 
         FIGS. 3 and 4  are images showing ureteral bypass devices of the type shown in  FIG. 1 , implanted in feline patients. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following describes what will be referred to as a ureteral bypass device (UBD) that is capable of treating causes of ureteral obstruction. The device can be used in humans (children and adults) and animals, regardless of etiology, species, or patient size, and can be optimized for the patient. In addition, the UBD of this invention beneficially allows for secure and facile placement of the device within the patient, as will be evident from the following discussion. 
       FIG. 1  represents a particular embodiment of a UBD  10  as comprising a pair of catheters  12  and  14  and a shunting adaptor  16  to which the catheters  12  and  14  are coupled. The adaptor  16  is represented in  FIGS. 1 and 2  as being configured as a shunting port, though from the following discussion it will become apparent that the certain features of a port would not be necessary in all embodiments of the invention. Distal ends  18  and  20  of the catheters  12  and  14  are adapted to be placed within, respectively, the renal pelvis and urinary bladder of a patient. As such, the catheters  12  and  14  can be referred to as nephrostomy and cystostomy catheters, respectively, though it should be evident that the catheters  12  and  14  are configured differently from prior art catheters of types used in ureteral bypass procedures. Suitable sizes for the catheters  12  and  14  will depend on the size of the patient and the drainage requirements. The diameters of the catheters  12  and  14  are preferably larger than traditional ureteral stents (limited by natural ureteral size) to provide better drainage. As nonlimiting examples, catheter sizes of 5 to 6 Fr will typically be suitable for cats, 6 Fr will typically be suitable for dogs, 5 to 8 Fr will typically be suitable for children and adults, though larger sizes (for example, 5 to 30 Fr) are possible and could be used if necessary. The lengths of the catheters  12  and  14  can also be tailored to meet the particular requirements of a patient. 
     Each catheter  12  and  14  is preferably equipped with a locking mechanism that retains its respective distal end  18  and  20  within the renal pelvis or urinary bladder of the patient, respectively. As represented in  FIG. 1 , the distal end  18  of the nephrostomy catheter  12  is configured as a locking loop (pigtail)  26 A capable of retaining the distal end  18  within the renal pelvis of a kidney for nephrostomy placement. To keep the locking loop  26 A coiled after being placed inside the renal pelvis, a string ( 22  in  FIG. 2 ) can be passed inside the catheter  12  from its locking distal end  18  and through a proximal end  24  of the catheter  12  at which the catheter  12  will be connected to the adaptor  16  ( FIG. 1 ). For example, the catheter  12  may be fluidically connected to the adaptor  16  via a male fitting  28  of the adaptor  16 , to which the catheter  12  is secured with a boot  32  formed of a biocompatible material, for example, silicone. The locking configuration shown for the distal end  18  in  FIG. 1  can be maintained by entrapping the string  22  by and between the boot  32 , the proximal end  24  of the catheter  12 , and/or the fitting  28  (represented in  FIG. 2  as a graduated barb). The distal end  20  of the bladder (cystostomy) catheter  14  can also be configured as a locking loop (pigtail) similar to the catheter  12  and its distal end  18 . In  FIG. 1 , the distal end  20  of the catheter  14  is represented as straight and equipped with a cuff  26 B adapted for adherence to the external serosal surface of a bladder. A particular example is a silicone catheter with a DACRON® cuff (or any other adhered material)  26 B for organ pexy to prevent leakage and ensure stability. As represented in  FIGS. 1 and 2 , the nephrostomy catheter  12  can also be equipped with a cuff  26 B, wherein the cuff  26 B can be provided instead of, or in addition to, the locking loop  26 A. The addition of a cuff  26 B to each catheter  12  and  14  can be advantageous, in that the cuff  26 B is able to form a secure adhesion without the need for direct attachment to the body wall for the kidney or urinary bladder (nephropexy or cystopexy), and in this manner promotes the ability of the catheters  12  and  14  to remain secure to the kidney capsule and bladder wall (serosa) and prevent leakage of urine during healing. The distal ends  18  and  20  of the catheters  12  and  14  are further represented as multi-fenestrated, in other words, having multiple fenestrations  34 . As is visible for the catheter  12  in  FIGS. 1 and 2 , a radio-opaque marker band  36  can be placed behind the last (most proximal) fenestration  34  to allow for fluoroscopic assurance that the entire loop  26 A and all fenestrations  34  are within the renal pelvis to prevent any extravasation or leakage of urine. 
       FIGS. 1 and 2  represent the catheters  12  and  14  and the adaptor  16  as separate components that must be assembled, though it is also within the scope of the invention that the UBD  10  could be manufactured as a single unitary component. In either case, the catheters  12  and  14  and adaptor  16  are adapted to be entirely implanted within a patient, in other words, under the skin (subcutaneously) or within the abdominal cavity (intra-abdominally) of a patient. As represented in  FIGS. 1 and 2 , each catheter  12  and  14  can be coupled to the adaptor  16  with one of the catheter boots  32 . In the embodiment of  FIGS. 1 and 2 , the boots  32  serve to prevent leaks, cover the locking string(s)  22 , and secure the catheters  12  and  14  to the fittings  28  of the adaptor  16 . The adaptor  16  can be configured to define an internal reservoir compartment (shunting port) that serves as a shunt between the catheters  12  and  14 . The fittings  28  of the adaptor  16  are represented in  FIG. 2  as male barbed fittings configured to provide male-to-male couplings with the catheters  12  and  14 , and are therefore preferably sized to correspond to the size of the catheters  12  and  14  and drainage requirements of the UBD  10 . In the embodiment of  FIGS. 1 and 2 , the adaptor  16  is equipped with two fittings  28 , one for each of the catheters  12  and  14 , so that the cystostomy catheter  14  fluidically communicates with a single nephrostomy catheter  12  through the compartment within the adaptor  16 . However, the adaptor  16  can be equipped with additional fittings, for example, a third fitting that enables a second nephrostomy catheter  12  to be coupled to the adaptor  16 , such that the UBD  10  can be implanted in the renal pelvis of each kidney of the patient and the cystostomy catheter  14  fluidically communicates with both nephrostomy catheters  12  (in the event of a bilateral ureteral obstruction). Advantageously, such a three-way design for the adaptor  16  eliminates the requirement in prior bilateral ureteral bypass procedures to implant two separate cystostomy catheters when necessary. 
     The adaptor  16  is also represented in  FIGS. 1 and 2  as being equipped with an entry site  30 , which is configured to provide an access to the adaptor  16  that allows for testing, sampling and flushing of the UBD  10 , and therefore enables occlusions, encrustation, and the like to be cleared or avoided. If the UBD  10  is to be placed intra-abdominally, the adaptor  16  would not be required to have an entry site  30 , in which case the adaptor  16  could essentially comprise two or more fittings  28  for connecting two or more nephrostomy catheters  12  to the cystostomy catheter  14 . An advantage of the entry site  30  is that it allows for the UBD  10  to be tested using contrast material and fluoroscopic guidance to ensure the patency of the system, as well as for urine sampling of the system directly, in a sterile manner. The entry site  30  is preferably configured as a septum that can be punctured by a needle, for example, a Huber point non-coring needle, which enables for multiple sampling and needle access without leakage. The adaptor  16  can be placed so that its entry site  30 , and particularly its septum, is in proximity to the patient&#39;s skin. As with ports employed with implantable venous access systems, the septum can be made of a self-sealing silicone rubber that can be punctured numerous and preferably thousands of times. Through its entry site  30 , the UBD  10  can be tested, such as with a contrast material and fluoroscopy to ensure patency and no leakage, sampled for infection, urinalysis, etc., and flushed if an occlusion is determined to exist within the catheters  12  and  14  or the adaptor  16 . If encrustation or occlusion has occurred, a needle can be used to inject a contrast material into the adaptor  16  via placing the needle through the patient&#39;s skin, through the entry site  30  of the adaptor  16 , and into the portal of the adaptor  16  to enable documentation of the occlusion site, all while the patent is awake. The entire UBD  10  can then be flushed of debris through the entry site  30  of the adaptor  16  to remove the occlusion. Access to the UBD  10  through the entry site  30  is able to promote the safety and effectiveness of long-term management of the UBD  10  without necessitating the need for testing using an invasive procedure, such as renal puncture. Furthermore, the ability to flush the entire UBD  10  of debris to remove an occlusion is not only diagnostically beneficial, but can also be potentially therapeutic for the patient. Also, since access to both the kidney and bladder catheters  12  and  14  is possible under the skin, in the event either catheter  12  and  14  needs to be exchanged, the procedure can be performed through a small skin incision at the port site and performed over a guidewire using fluoroscopic visualization without the need for further surgery. 
     A preferred procedure for placing the UBD  10  within a patient is to use a modified version of the well-known modified-Seldinger technique utilizing a guidewire and preferably under fluoroscopic guidance. Alternatively, a direct-stick method can be performed without guidewire access. Using a modified-Seldinger technique, an incision is made at a sterilized site through which the components of the UBD  10  will be implanted. It is not necessary to implant the completed assembly for the UBD  10  shown in  FIG. 1 , but instead, the catheters  12  and  14  and adaptor  16  can be implanted separately (if not manufactured as a unitary component). Punctures can be made in each of the renal pelvis and the urinary bladder with separate renal access needles (not shown), suitably sized for the desired guidewire size (typically 18 gauge renal access needle with a 0.035″ guidewire), For both nephrostomy and cystostomy placement, a guidewire can then be advanced through the access needle and coiled inside the renal pelvis or urinary bladder. The access needle is then removed over the wire and the distal ends  18  and  20  of the catheters  12  and  14  can be respectively placed over the wire, inside the renal pelvis and urinary bladder. Each catheter  12  and  14  is preloaded with a hollow trocar  38  to maintain the stiffness and pushability to advance the respective catheter  12 / 14  over the wire. Whether the patient is human or animal, if the distal end  18  of the nephrostomy catheter  12  is configured as a locking loop  26 A, the renal pelvis is preferably dilated to accommodate the locking loop  26 A. An alternative is to use the hollow trocar  38  with a sharp stylette  40  (the sharp tip and cap of which are seen in  FIG. 2 ) to directly puncture the renal pelvis or urinary bladder without the use of the modified-Seldinger technique or need for a guidewire. 
     The distal end  18  of the nephrostomy catheter  12  can then be actuated with the string  22  to form the locking loop  26 A, which prevents the catheter  12  from becoming dislodged once placed within the patient. Similarly, the distal end  20  of the cystostomy catheter  14  is secured with the cuff  26 B (or, if so equipped, a locking loop  26 A) to prevent the catheter  14  from becoming dislodged from the urinary bladder. Both catheters  12  and  14  can be cut to an appropriate length, based on patient needs, prior to being fluidically connected to the adaptor  16  via the fittings  28 . The boots  32  can then be advanced onto the proximal ends  24  of the catheters  12  and  14  to connect and secure the catheters to the adaptor  16 . The locking string(s)  22  of the catheter(s)  12  and/or  14  are secured to the adaptor  16  by advancing the boots  32  over the junctions formed by the fittings  28  and the catheters  12  and  14 . The adaptor  16  is then implanted and secured under the skin to subcutaneous tissue, after which the incision can be closed. As previously noted, the incision is preferably closed so that the entry site  30  of the adaptor  16  (if so equipped) is accessible through the patient&#39;s skin with simple needle access. The completed assembly of the UBD  10  is entirely located internally of the patient, and typically located subcutaneously, on the surface of the abdominal wall, though a completely intra-abdominal option is also possible. The entry site  30  is accessible through the patient&#39;s skin to provide a leak-free access port for testing, sampling and flushing of the UBD  10  with an appropriate needle, such as a non-coring Huber needle. 
     From the above, it should be appreciated that the present invention provides for facile and secure implantation of the UBD  10  within a patient. The UBD  10  provides the capability for easy sampling of the UBD  10  for infection, urinalysis, or the like, allows for testing the entire UBD  10  with contrast material to ensure patency and no leakage. The UBD  10  can also be flushed if an occlusion is discovered within the UBD  10 , or serially to prevent an occlusion. Needle access directly into this UBD  10  (via the entry site  30 ) makes long-term management of the UBD  10  safe, non-painful, non-invasive, and effective without the requirement for risky, invasive testing procedures that provide only diagnostic utility without any therapeutic options. 
     In addition, if the UBD  10  is assembled from individual components (catheters  12  and  14  and adaptor  16 ), replacement of one of the catheters  12  or  14  or adaptor  16  can be accomplished without requiring complete removal of the entire UBD  10  or an additional invasive surgery. The catheters  12  and  14  and adaptor  16  can be segmentally exchanged over a guidewire if necessary, which can be readily accomplished using fluoroscopic guidance and a guidewire without complete removal and exchange of the entire UBD  10 . As a result, replacement of components of the UBD  10  can be accomplished through a small incision in the patient&#39;s skin covering the entry site  30  of the adaptor  16 , without requiring entry into the abdomen. This capability circumvents the need for a major surgical procedure to replace the UBD  10  in its entirety, and allows utilization of the same tunnel that was formed previously within the patient. A UBD  10  assembled from individual components also enables physicians and veterinarians to choose if he/she prefers to use catheters  12  and  14  with two locking-loops  26 A or, as represented in  FIGS. 1 and 2 , a single locking loop  26 A and a straight catheter  14  for individual patients (perhaps depending upon on completely percutaneous placement versus open surgical placement). 
     Finally, in patients that require bilateral diversion (about 10 to 20%, depending on cause), the adaptor  16  can have a three-way configuration, by which the adaptor  16  is equipped with a third fitting  28  to allow a second nephrostomy catheter to be connected to the single cystostomy catheter  14  through the adaptor  16 . As a result, only a single access point is required to the urinary bladder, and less artificial material is implanted in the patient. 
     A UBD  10  of the type shown in  FIGS. 1 and 2  has been trialed in thirty-four feline patients and two canine patients for various causes of ureteral obstruction. The trials showed the UBD  10  to be successful and patent for urinary drainage long-term (typically at least 24 months and in some cases more than three years), with very few associated complications. None of the devices developed encrustation, occlusion or dislodgement in the long-term with the practice of serial flushing (every 3-6 months when necessary on an out-patient basis). 
       FIG. 3  shows two images of feline patients in which UBDs of this invention have been implanted. In the lefthand surgical image (B), a ventrodorsal radiograph shows a UBD implanted on the left side of a feline patient. The proximal ends of each of the nephrostomy and cystostomy catheters are shown attached to a metallic adaptor (shunting port) and their distal ends are equipped with a locking loop coiled within, respectively, the renal pelvis or urinary bladder of the patient. Image (C) is a lateral fluoroscopic image of a feline patient during injection of a contrast material into the port of a UBD through its entry site using a non-coring Huber needle. The Huber needle has been inserted through a silicone rubber septum that forms the entry site under the skin, and the UBD is being flushed with the contrast material under fluoroscopic guidance. The contrast material can be seen as filling the renal pelvis, urinary bladder and ipsilateral ureter, confirming patency of the device. This particular patient also has a double-pigtail ureteral stent inside the contralateral ureter that had been placed previously. 
       FIG. 4  shows another image of a feline patient in which a UBD of this invention has been implanted. The image in  FIG. 4  is a lateral abdominal radiograph of the patient with a left-sided ureteral stent and a right-sided UBD of this invention. The nephrostomy catheter of the UBD has a locking loop within the renal pelvis and a DACRON®/silicone cuff attached to the renal capsule. The nephrostomy catheter is tunneled through the body wall of the renal pelvis to the port, which is located in the subcutaneous tissue. The cystostomy catheter is a straight, multi-fenestrated catheter that passes through the apex of the urinary bladder and is equipped with a DACRON®/silicone cuff adhered to the outside of the bladder wall (serosa) for security. In contrast to the UBDs of  FIG. 3 , the UBD in  FIG. 4  is not pexied to any internal body wall but instead to the rention cuffs. 
     While the invention has been described in terms of preferred embodiments, it is apparent that other forms could be adopted by one skilled in the art. For example, the ureteral bypass device could differ in appearance and construction from the embodiment disclosed, the functions of each component of the device could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function, and appropriate materials could be substituted for those noted. Therefore, the scope of the invention is to be limited only by the following claims.