Abstract:
Devices, methods, and systems provide a catheter-based device comprising an expandable portion that is placed distally of the obstructive or occluding mass, which substantially prevents fragments generated by ablating the occluding mass with a lithotripter, for example, a laser lithotripter, from traveling upstream, thereby improving the safety and effectiveness of lithotripsy Some embodiments of the device further comprise a through lumen through which fluid is introduced into a renal collecting system, thereby maintains positive pressure that biases the fragments generated by lithotripsy from entering the collecting system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/172,586, filed Apr. 24, 2009, the entire disclosure of which is hereby incorporated by reference as if set forth in full herein 
     
    
     BACKGROUND 
       [0002]    This disclosure is related to medical devices, and more particularly, to a renal flushing catheter useful in lithotripsy of ureteral calculi. 
         [0003]    Devices that assist in the removal or retrieval of ureteral calculi or stones generally comprise basket-like structures that are sized and configured to capture such a mass so that it can be mobilized or held in position. 
         [0004]    However, there remains a need for a device that facilitates the use of a directed energy source, such as a laser, to fragment a luminal mass, such as a urinary stone, by specifically blocking fragments from moving upstream in the ureter, that is, in the direction of the directed energy. In addition, there is a need for a device that biases a fluid flow through the ureter, thereby propelling fragments in a retrograde direction. 
       SUMMARY 
       [0005]    Devices, methods, and systems provide a catheter-based device comprising an expandable portion that is placed distally of the obstructive or occluding mass, which substantially prevents fragments generated by ablating the occluding mass with a lithotripter, for example, a laser lithotripter, from traveling upstream, thereby improving the safety and effectiveness of lithotripsy. Some embodiments of the device further comprise a through lumen through which fluid is introduced into a renal collecting system, thereby maintains positive pressure that biases the fragments generated by lithotripsy from entering the collecting system. 
         [0006]    In one embodiment, a catheter based occlusive device for use within a body lumen to maintain a gradient fluid pressure and form a luminal blockage is provided. The device comprises an elongate luminal catheter body having a lumen extending from a proximate end to a distal end of the catheter body and a plurality of expandable portions near the distal end of the catheter body. In the low-profile state, each of the expandable portions has a crossing profile sufficient to permit placement of the expandable portion distal of a ureteral mass, and in the high-profile state, each of the expandable portions substantially block fragments generated by lithotripsy of the ureteral mass from traveling distally thereof. 
         [0007]    In another embodiment, a catheter based occlusive device for use within a body lumen to maintain a gradient fluid pressure and form a luminal blockage is provided. The catheter comprises an elongate luminal catheter body having a lumen extending from a proximate end to a distal end of the catheter body and a plurality of expandable portions attached to the distal end of the catheter body. The plurality of expandable portions has a low-profile state and a high-profile state and the lumen of the catheter body provides a fluid conduit to inject irrigation fluid out the distal end of the catheter body and distally from the plurality of expandable portions. The plurality of expandable portions in the high-profile state obstructs fragments of a ureteral mass from traveling distally thereof and does not obstruct the fluid conduit. 
         [0008]    Many of the attendant features of the present invention will be more readily appreciated as the same becomes better understood by reference to the foregoing and following description and considered in connection with the accompanying drawings in which like reference symbols designate like parts throughout. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a common urinary tract, urinary bladder, ureters, and kidneys. 
           [0010]      FIG. 2A  illustrates a common urinary tract obstruction in a ureter and an embodiment of a renal flushing catheter in a low-profile state in place within the ureter.  FIG. 2B  illustrates the renal flushing catheter illustrated in  FIG. 2A  comprising a plurality of inflatable balloons in an expanded state.  FIG. 2C  is a perspective view of an embodiment of a distal end of the catheter illustrated in  FIGS. 2A and 2B  in the expanded state.  FIG. 2D  is a detailed view of the upper portion of  FIG. 2C  illustrating directing energy upon a luminal obstruction. 
           [0011]      FIG. 3  illustrates an embodiment of a collection vessel. 
           [0012]      FIG. 4A  is a perspective view of an expandable portion of another embodiment of a renal flushing catheter comprising a radially expandable mesh expandable portion in a low-profile state.  FIG. 4B  is a perspective view of the expandable portion illustrated in  FIG. 4A  in a high-profile state  FIG. 4C  illustrates the renal flushing catheter illustrated in  FIGS. 4A and 4B  with the expandable portion in the expanded state placed distally of a occluding mass. 
           [0013]      FIG. 5A  is perspective view of an expandable portion of another embodiment of a renal flushing catheter comprising a plurality of cone-shaped members in a low-profile state.  FIG. 5B  is perspective view of the expandable portion illustrated in  FIG. 5A  in a high-profile state.  FIG. 5C  illustrates the renal flushing catheter illustrated in  FIGS. 5A and 5B  with the expandable portion in the expanded state placed distally of a occluding mass. 
           [0014]      FIG. 6  illustrates another embodiment of a renal flushing catheter comprising an expandable portion that is cone-shaped in an expanded state. 
           [0015]      FIG. 7A  is a perspective view of an expandable portion of another embodiment of a renal flushing catheter comprising a convoluted mesh expandable portion in a low-profile state.  FIG. 7B  is a perspective view of the expandable portion illustrated in  FIG. 7A  in a high-profile state.  FIG. 7C  illustrates another embodiment of a renal flushing catheter comprising a convoluted mesh structure.  FIG. 7D  is a detailed view of the upper portion of  FIG. 7C  illustrating directing energy upon a luminal obstruction. 
           [0016]      FIG. 8  illustrates another embodiment of a renal flushing catheter in which an expandable portion comprises a linearly compressible woven fabric. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  illustrates a urinary tract  10  comprising a urinary bladder  40 , a pair of ureters  30 , and a pair of kidneys  20 . As shown in  FIG. 2A , occasionally, a mass  80  forms within the urinary tract  10  and becomes lodged within the lumen of the ureter  30 , thereby obstructing or occluding the ureter  30 . The mass  80  may be very solid and tractive within the lumen. Because the mass  80  will continue to grow and eventually completely block the ureter  80 , it is necessary to remove or dissolve such a mass. The mass  80  is fragmented or ablated using a lithotripter, which comprises an energy source that emits directed energy suitable for fragmenting the mass  80 . The resulting fragments are then removed from the lumen of the ureter  30 . Suitable energy sources typically generate a localized shock wave that mechanically fragments the mass, for example, at least one of ultrasonic sound waves, electrically-generated shock waves, or laser energy. Those skilled in the art will appreciate that delivering strong, focused energy to the mass  80  within a ureteral lumen  30  can move the mass  80  and/or fragments thereof upstream, that is, back toward the renal collecting system  60 , which is a very undesirable outcome. Fragments in the collecting system  60  are not typically flushed therefrom and seed additional calculi. 
         [0018]    In some cases, a physician deploys a holding device that can capture or contain the mass  80  and hold it securely while it is fragmented by the lithotripter. Such procedures are sometimes problematic, however, especially using laser lithotripsy, because the holding device may be damaged and/or destroyed in the lithotripsy process. For example, where the holding device comprises a metallic wire “basket”, portions of the basket surviving the lithotripsy may present a serious problem for removal of the device. An inflatable balloon placed behind the mass may provide a better option; however, the lithotripsy energy can rupture the balloon, after which fragments thereof may then move upstream. 
         [0019]      FIG. 2A  illustrates an embodiment of a renal flushing catheter  200  in a low-profile state positioned in a urinary tract  10 . The renal flushing catheter  200  comprises an elongate body  210  comprising a proximal end  212  and a distal end  214 . The distal end  214  is sized and configured to easily pass alongside the ureteral mass  80  in the undeployed, low-profile state when the catheter  200  is positioned, as illustrated in  FIG. 2A . The distal end  214  comprises an expandable occluding portion  230 . The proximal end  212  comprises an activation member, the use of which is discussed below. 
         [0020]    Some embodiments of the elongate body  210  comprise two coaxial, tubular members that are relatively slidable Relatively sliding the coaxial, tubular members applies or releases tension on the expandable member  230 , thereby converting the expandable portion  230  between the low-profile state illustrated in  FIG. 2A  and a high-profile state illustrated in  FIG. 2B . In other embodiments, the elongate body  210  comprises an inflation lumen through which applying or releasing pressure converts the expandable member  230  between the low-profile state and the high-profile state. Some embodiments of the elongate body  210  comprise one or more additional lumens, in which, for example, at least a portion of a visualization system is disposed, which is used during placement of the catheter  200  and/or fragmentation of the mass  80 . In some embodiments, at least a portion of a lithotripsy or energy delivery system is disposed in the one or more additional lumens. 
         [0021]    The expandable portion  230  is characterized by a “crossing profile”, which is defined as a largest diameter of the expandable portion  230  in the low-profile state. A smaller crossing profile facilitates positioning the distal end  214  of the catheter around the mass  80 , particularly, in cases in which the mass  80  is large, and/or the lumen of the ureter  30  has a small diameter. In some embodiments, the crossing profile of the expandable portion  230  is not greater than about 2 mm, 1.6 mm, 1.35 mm, 1 mm, or 0.65 mm (about 0.025″) In some embodiments, the crossing profile of the expandable portion  230  is not greater than about 4 French, 3 French, or 2 French. In some embodiments, the expandable portion  230  comprises one or more expandable features that have diameters greater than the crossing profile when the expandable portion  230  is in the high-profile state. In some embodiments, a diameter of an expandable feature in the high-profile state is at least about 0.9 mm (about 0.035″), 5 mm, 6 mm, or 7 mm. In some embodiments, the diameter of an expandable feature in the high-profile state is at least about 6 French, 8 French, 15 French, or 17 French. Embodiments of the expandable portion  230  resist failure during ablation of the mass  80 , for example, using a laser. For example, embodiments of the expandable portion  230  are configured and constructed such that laser energy incident on the expandable portion  230  in the high-profile state affects only relatively small portions thereof, thereby maintaining an occluding “backstop” upstream of any portion of the expandable portion  230  that are ablated by the directed energy. 
         [0022]      FIG. 2C  is a perspective view of the distal end  110  of the catheter  200  illustrated in  FIG. 2B  in which the expandable portion  230  is in the high-profile state In the illustrated embodiment, the expandable feature of the expandable portion  230  comprises a plurality of inflatable balloons  232   a - 232   d.  In the low-profile state, for example, as shown in  FIG. 2A , the balloons  232   a - 232   d  present a low crossing profile. A through lumen  220  opens at the extreme distal end  214  of the catheter body  210  in the illustrated embodiment. The balloons  232   a - 232   d  are distensible. Some embodiments of the balloons comprise at least one of an elastomeric polymer, polyurethane, polyisoprene, styrene-butadiene, silicone, ethylene-propylene rubber, and the like. Some embodiments of the balloons are fenestrated. 
         [0023]    In use, the catheter  200  is positioned in the urinary tract  10  with the expandable portion  230  in the low profile state, as illustrated in  FIG. 2A . In some embodiments, the progress of the distal end  214  relative to the ureteral mass  80  is monitored using a visualization system. After the expandable portion  230  has been advanced past the mass  80 , the expandable portion  230  is converted into the high profile state using the activation member. 
         [0024]      FIG. 2D  is a detailed view of the upper portion of the ureter and kidney illustrated in  FIG. 2B  with the catheter  200  deployed therein. In the illustrated embodiment, the activation member pressurizes the inflation lumen, thereby inflating the individual balloons  232   a - 232   e  upstream of the ureteral mass  80 . In some embodiments, the inflation is visually monitored. An irrigating fluid is then delivered under low pressure through the through-lumen  220  upstream of the balloons  232   a - 232   e,  thereby partially filling the collecting system  60  of the kidney. The balloons  232   a - 232   e  seal the ureter, thereby retaining the fluid in the collecting system  60 . In one embodiment, the balloons in a high-profile and/or low-profile state do not obstruct the through-lumen  220  and/or a fluid conduit through which the irrigating fluid is introduced. In another embodiment, the balloons obstruct or seal the through-lumen and/or fluid conduit when the balloons are in a high-profile state. A lithotripter  260 , for example, a laser lithotripter, is then be “fired” or activated, which delivers a pulse  262  of directed energy that fragments or ablates the ureteral mass  80  using the most proximal, balloon  232   a  as a “backstop”. An example of a suitable laser lithotripter includes a holmium laser lithotripter. Any energy not absorbed by the ureteral mass  80 , for example, from a misfire, is likely to pop the balloon  232   a , which deflates. The next, redundant balloon  232   b  now serves as the “backstop” for the next firing of the laser  260 . The sequence may be repeated until the ureteral mass  80  is fragmented and all of the balloons  232  are deflated and/or destroyed, thereby releasing the irrigation fluid from the renal collecting system  60 . In one embodiment, one or more of the expandable portions, e.g., the proximate balloon  232   a,  is destructible or susceptible to destruction by, for example, a laser lithotripter, and one or more of the other expandable portions, e.g., distal balloon  232   e,  is not destructible or more resistant to destruction. With the balloons  232  in a low profile state, the fluid carries the ablated fragments proximally or downstream. 
         [0025]      FIG. 3  illustrates an embodiment of a collection vessel  370  fluidly connected to the proximal end  50  of the urinary tract through a tube  372 . In the illustrated embodiment, the collection vessel  370  comprises a transparent tapered collection bag  374  comprising a bottom portion  376  dimensioned and configured as a collection reservoir. In the illustrated embodiment, the bottom portion  376  comprises calibrated indicia  378 , thereby permitting a user to assess and compare the fragment mass  80   a  with the estimated pre-operative mass of the occluding mass  80  within the ureter  30 . 
         [0026]    In some embodiments, a ureteral stent is then placed to maintain the patency of the ureter  30 . In one embodiment, the ureteral stent is removable and placed around the catheter body surrounding all or a portion of the plurality of expandable balloons or portions of the catheter. In some embodiments, the catheter  100  serves as a guidewire over which the stent is inserted. The catheter  100  is then withdrawn. 
         [0027]    In other embodiments, a guidewire is advanced through the through lumen  220  of the catheter and catheter  100  is withdrawn. The stent is then advanced over the guidewire and placed. The guidewire is then withdrawn. 
         [0028]      FIG. 4A  is a perspective view of another embodiment of an expandable portion  430  of a renal flushing catheter  400  in a low-profile state, and  FIG. 4B  is a perspective view of the expandable portion  430  in a high-profile state. The renal catheter  400  is generally similar to the embodiment discussed above and illustrated in  FIGS. 2A-2D . In the illustrated embodiment, the catheter  400  comprises a catheter body  410  comprising a proximal end  412  and a distal end  414 . A through-lumen  420  extends through the catheter body  410 , terminating at the distal end  414 . In the illustrated embodiment, the catheter body  410  comprises an inner tube  440  and an outer tube  450 , which are coaxial and relatively slidable longitudinally. In some embodiments, the inner tube  440  and outer tube  450  are also relatively rotatable. The relative positions, longitudinal and/or rotational, between the inner tube  440  and outer tube  450  are controlled by an activation member disposed at the proximal end  412  of the catheter. 
         [0029]    As discussed above, the expandable portion  430  is disposed proximate to the distal end  414  of the catheter. In the illustrated embodiment, the expandable portion  430  comprises a cylindrical, braided fabric element  432 , which comprises a proximal end  434  and a distal end  436 . The distal end  436  of the fabric element is coupled with the inner tube  440  of the catheter body, and the proximal end  434  is coupled to the outer tube  450 . Because the inner tube  440  and outer tube  450  are relatively slidable, adjusting their relative positions compresses or tensions the fabric element  432 . Those skilled in the art will understand that in other embodiments, the inner tube  440  is coupled to the proximal end  434 , and the outer tube  450  is coupled to the distal end  436 . 
         [0030]    In some embodiments, a diameter of the braided fabric element  432  varies predictably with its length. In the embodiment illustrated in  FIGS. 4A and 4B , the expandable portion  430  is maintained in a desired crossing profile by applying tension upon the braided element  430  through the inner tube  440  and the outer tube  450 . In some embodiments, the expandable portion  430  is expanded by adjusting and/or releasing the applied tension to provide a generally cylindrical portion  430  in the high-profile state with a larger diameter and a shorter length compared with the dimensions in the low profile state. In some embodiments, the expandable portion  430  is further expanded or deployed by at least one of linearly compressing, twisting, and/or otherwise deforming the braided element  432 , for example, by relatively adjusting the positions of the inner tube  440  and the outer tube  450 . In some embodiments, the degree of expansion of the braided element  432  is visually monitored.  FIG. 4C  illustrates a urinary tract in which the renal flushing catheter  400  is placed with the expandable portion  430  deployed upstream of a ureteral mass  80 . 
         [0031]    Embodiments of the braided mesh fabric comprise at least one of a polymer, polymer, polyester, polyamide, polytetrafluoroethylene, and polyurethane. The braided mesh fabric comprises a plurality of bias-woven fibers, and as such, is damage tolerant because damage to a few fibers will not cause the structure to fail. In some embodiments, the braided element  430  in the high-profile state permits a degree of fluid flow therethrough, thereby reducing the chance of over pressurizing the collection system  60 . 
         [0032]      FIG. 5A  is a perspective view of a distal end  514  of another embodiment of a renal flushing catheter  500  in a low-profile state.  FIG. 5B  is a perspective view of the distal end  514  in a high-profile state. The catheter  500  illustrated in  FIGS. 5A and 5B  is generally similar to the embodiments described above, and illustrated in  FIGS. 4A-4C . An expandable portion  530  comprises a cylindrical braided mesh element  532  in the low-profile state. In the high profile state, the expandable portion  530  comprises a proximal cone  532   a,  a distal cone  532   b,  and a cylindrical portion  532   c  disposed therebetween. In the illustrated embodiment, the proximal cone  532   a  points proximally and the distal cone  532   b  points distally. In the illustrated embodiment, the proximal cone  532   a  and the distal cone  532   b  are generally symmetrical, with similar diameters and lengths. A diameter of the cylindrical portion  532   c  is smaller than the largest diameters of the proximal cone  532   a  and the distal cone  532   b.    FIG. 5C  is a view of an upper portion of a urinary tract with the catheter  500  placed therein with the expandable portion  530  deployed distally of a ureteral mass  80 . In one embodiment, each portion can be individually or group manipulated, deformed and/or destroyed to reversibly move from a low-profile to a high-profile state. In various other embodiments, one or more portions have a different material characteristic, structure and/or placement relative to the other portions or catheter to assist in the reversible deployment or expansion of the portions to obstruct or not obstruct fluid flow and/or the ureteral mass or portion thereof. 
         [0033]      FIG. 6  is a view of an upper portion of a urinary tract with another embodiment of a catheter  600  placed therein with an expandable portion  630  deployed distally of a ureteral mass  80 . The catheter  600  is generally similar to the embodiments described above and illustrated in  FIGS. 5A and 5B  except that in the high-profile state, the expandable portion  630  comprises a braided mesh  632  in the shape of a cone pointed distally. 
         [0034]      FIG. 7A  illustrates in perspective view a distal end  714  of another embodiment of a catheter  700  with an expandable portion  730  in a low-profile state.  FIG. 7B  is a perspective view of the distal end  714  with the expandable portion  730  in a high-profile state. The catheter  700  is generally similar to the embodiments described above and illustrated in  FIGS. 4A-6 . In the illustrated embodiment, the expandable portion  730  comprises a generally helical or spiral deformable-film or deformable-mesh structure  732 . Applying tension and/or torsion to the film or mesh structure  732 , for example, by adjusting the relative positions of an inner tube  740  and an outer tube  750  coupled thereto as described above, maintains or converts the expandable portion  730  to the low-profile state illustrated in  FIG. 7A . Releasing and/or reversing the tension or torsion converts the expandable portion  730  to the high-profile state illustrated in  FIG. 7B , thereby wrinkling the film or mesh structure  732 , which occludes or partially occludes the ureteral lumen  30 , as illustrated in  FIGS. 7C and 7D . Although the illustrated embodiment does not totally occlude the lumen  30 , the torturous pathway created by the convoluted expandable portion  730  prevents upstream migration of ablated fragments of the ureteral mass  80 . 
         [0035]      FIG. 8  is a view of a urinary tract with another embodiment of a catheter  800  placed therein with an expandable portion  830  in a high profile state deployed distally of a ureteral mass  80 . The catheter  800  is generally similar to the embodiments described above and illustrated in  FIGS. 4A-4C  except that the expandable portion  830  comprises a compressible fabric  832 . The expandable portion  830  is converted to the high-profile state by compressing and/or twisting the compressible fabric  832 . 
         [0036]    In another embodiment of a renal catheter (not illustrated), the expandable portion comprises a braided mesh element or a compressible fabric element, and at least one balloon disposed distally thereof. 
         [0037]    Use of the embodiments of the catheters illustrated  FIGS. 4A-8  in removing a ureteral mass is similar to the use of the embodiment illustrated in  FIGS. 2A-2D . The following description references the embodiment illustrated in  FIGS. 7C and 7D , but is applicable to all of the embodiments illustrated in  FIGS. 4A-8 . After placing the expandable portion  730  of the catheter distal of the ureteral mass  80  with the expandable portion  730  in the low profile state, the film or mesh structure  730  is deployed, thereby converting the expandable portion  730  to the high-profile state, as illustrated in  FIGS. 7C and 7D . In some embodiments, placing the catheter  700  and/or deploying the expandable portion  730  is visually monitored. A lithotripter  760 , for example, a laser lithotripter, is then activated, thereby emitting energy  762  that fragments the mass  80 . In some embodiments, the mesh or film structure  732  is not appreciably damaged by the emitted energy  762 . The deployed mesh or film structure  732  prevents fragments of the mass  80  from migrating upstream. 
         [0038]    An irrigating fluid is introduced into the through lumen  720  at the proximal end  712  of the catheter and exits at the distal end  714  of the catheter, which is upstream of the ureteral mass  80  and the deployed expandable member  730  of the catheter. The bolus of irrigation fluid is placed within the collecting system, under very low pressure. The fluid “leaks” retrograde through the expandable member  730 , which in the illustrated embodiment does not completely occlude the ureter  30 . The fluid urges ablated fragments from the ureteral mass  80  proximally towards a proximal exit path  50 . In some embodiments, the fluid and fragments are collected as described above. Adding fluid to the lumen distal of the mass  80  also helps in maintaining a safer ambient temperature, which is especially important when using a laser lithotripter. 
         [0039]    Although this invention has been described in certain specific embodiments, many additional modifications and variations would be apparent to those skilled in the art. It is therefore to be understood that this invention may be practiced otherwise than specifically described, including various changes in the size, shape and materials, without departing from the scope and spirit of the present invention. Thus, embodiments of the present invention should be considered in all respects as illustrative and not restrictive, the scope of the present invention to be determined by the appended claims and their equivalents rather than the foregoing description.