Abstract:
A catheter system and method are provided for delivering a substance, such as medication, to body tissue. The catheter system includes a medication delivery tube and at least one heat transfer fluid passage that at least partially surrounds the medication delivery tube. The catheter system may be used to deliver temperature-sensitive substances, such as, for example thermo-sensitive polymers, to living tissue.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention is related generally to catheters, and specifically to catheters for delivery of substances at controlled temperatures. 
       BACKGROUND 
       [0002]    Catheters are widely used in the medical field, for various procedures such as, for example, angioplasty, stent delivery, cryogenic, and drug delivery. Catheters for local drug delivery have been developed to offer regional or site-specific delivery. Site-specific catheters permit an improved delivery of a therapeutic agent to be infused at specific sites of living tissue. By using passive or active diffusion properties, catheters are able to deliver pharmaceuticals, including temperature-sensitive drugs, as well as genetic agents, to living tissues. 
         [0003]    Stimuli sensitive polymers, such as hydrogels and liposome drug carriers, respond to changes in temperature and metabolites. Thermo-sensitive polymers are water soluble below a lower critical solution temperature and are water insoluble above the lower critical solution temperature. For clinical applications, these polymers may be formulated to become insoluble (e.g., form a gel), at body temperature. Promising applications of such polymers include cellular therapy, embolization procedures, tissue sealants, and for targeted delivery of medical isotopes or chemotherapy drugs to treat problematic solid tumors, such as those associated with liver, pancreas, brain, breast, and prostate tissue. 
         [0004]    However, catheters that are currently commercially available lack an efficient temperature-controlled delivery system for such polymer-type materials. 
         [0005]    The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art. 
       SUMMARY 
       [0006]    In accordance with one aspect of the invention, a catheter system includes a medication delivery tube and at least one heat transfer fluid passage that at least partially surrounds the medication delivery tube. The medication delivery tube may terminate in a needle portion. The catheter system may further include an insulating portion that at least partially surrounds the heat transfer fluid passage. The heat transfer fluid passage and the medication delivery tube may be disposed in a coaxial configuration. The heat transfer fluid passage may include an inflow passage and an outflow passage, one or both of which may be configured, for example, as a C-shaped lumen passage. The heat transfer fluid passage may include a tube coiled around the medication delivery tube. 
         [0007]    In accordance with another aspect of the invention, a catheter system includes a medication delivery tube and at least one heat transfer fluid passage that is disposed adjacent to the medication delivery tube. An insulating portion may be provided that at least partially surrounds the heat transfer fluid passage, and the heat transfer fluid passage and the medication delivery tube may be disposed in a coaxial configuration. The heat transfer fluid passage may include an inflow passage and an outflow passage, one or both of which may be configured as a C-shaped lumen passage. 
         [0008]    In accordance with yet another aspect of the invention, a method of delivering a substance into living tissue is provided. The method includes providing a catheter that includes a delivery tube and a heat transfer fluid passage that at least partially surrounds the delivery tube, maintaining a desired delivery temperature by circulating a heat transfer fluid through the heat transfer fluid passage, and delivering the substance into living tissue through the delivery tube at the desired delivery temperature. The heat transfer fluid may be, for example, water, or, alternatively, saline solution. The substance may be delivered in liquid form and may be in gel form at a temperature approximately equal to a temperature of the living tissue. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a partially cross-sectional diagrammatic perspective view of a first embodiment of a catheter system; 
           [0010]      FIG. 2  is a partially cross-sectional diagrammatic perspective view of a second embodiment of a catheter system; and 
           [0011]      FIG. 3  is a partially cross-sectional diagrammatic perspective view of a third embodiment of a catheter system. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    A first embodiment of a catheter system in accordance with one aspect of the invention is depicted in  FIG. 1 , in which as catheter system  10  includes a medication delivery tube  12  that is at least partially surrounded in a coaxial fashion by a heat transfer fluid passage  14 . The heat transfer fluid passage  14  may be at least partially surrounded by an insulating membrane  16  that is in turn housed within an outer sheath  18 . A distal end  20  of the catheter system  10  may be unsealed, and thus heat transfer fluid may exit the catheter system  10  at the distal end  20 . The medication delivery tube  12  may terminate in a needle portion  22 . 
         [0013]    The medication delivery tube  12  may be in fluid communication with an injection port  24  that may be, for example, connected to a syringe (not shown) for drug delivery purposes. The heat transfer fluid passage  14  may be in fluid communication with an inlet port  26  that may be used to continuously flow a heat transfer fluid, such as, for example, chilled water, within the heat transfer fluid passage  14 , using an external pump (not shown). A plurality of spacer elements  28  may be provided to securely position the medication delivery tube  12  with respect to the insulating membrane  16 . 
         [0014]    A substance, such as a medication (not shown) may thus be injected through the injection port  24 , while heat transfer fluid is flowing through the heat transfer fluid passage  14 , thereby maintaining the medication at a regulated desired temperature (e.g., cooled below body temperature, for example, below about 98.6 degrees Fahrenheit). Other fluids, such as, for example, saline solution, may be used for the heat transfer fluid. 
         [0015]    The insulating membrane  16  may be made from polyvinyl chloride (PVC), or any other suitable material, such as polytetrafluoroethylene (PTFE) or polyimide. The outer sheath  18 , the medication delivery tube  12 , and the spacer elements  28  may also be composed of PVC, PTFE, or Polyimide material, and the needle portion  22  may be made of stainless steel hypotubing. 
         [0016]    A second embodiment of the invention is depicted in  FIG. 2 , in which a catheter system  116  includes a medication delivery tube  112  that is at least partially surrounded by a heat transfer fluid passage  114 . An insulating membrane  116  at least partially surrounds the heat transfer fluid passage  114 , and that is in turn housed within an outer sheath  118 . The medication delivery tube  112  may be in fluid communication with an injection port  124 . The heat transfer fluid passage  114  may be in fluid communication with an inlet port  120  and an outlet port  122 . The medication delivery tube  112  may terminate in a needle portion  113 . 
         [0017]    The heat transfer fluid passage  114  may be divided by a wall  130  into an inflow passage  126  and an outflow passage  128 . The wall  130  may include a plurality of openings  132  to facilitate flow of heat transfer fluid between the inflow passage  124  and the outflow passage  126 . The inflow passage  126  and the outflow passage  128  may be configured as C-shaped lumen passages. The heat transfer fluid passage  114  may be sealed at a distal end  134 . 
         [0018]    The insulating membrane  116  may be made from polyvinyl chloride (PVC), or any other suitable material, such as polytetrafluoroethylene (PTFE) or polyimide. The outer sheath  118  and the medication delivery tube  112  may also be composed of PVC, PTFE, or Polyimide material, and the needle portion  113  may be made of stainless steel hypotubing. 
         [0019]    A third embodiment of the invention is depicted in  FIG. 3 , in which a catheter system  210  includes a medication delivery tube  212  that is partially surrounded by a heat transfer fluid passage  214 , that may be, for example coiled around the medication delivery tube  212 , or otherwise placed in close proximity or adjacent to the medication delivery tube  212 . The medication delivery tube  212  may terminate in a needle portion  213 . 
         [0020]    An insulating membrane  216  may at least partially surround the heat transfer fluid passage  214  and the medication delivery tube  212 . The medication delivery tube  212  may be connected in fluid communication with an injection port  218 , and the heat transfer fluid passage  214  may be in fluid communication with an inlet port  220  and an outlet port  222 . 
         [0021]    The insulating membrane  216  may be made from polyvinyl chloride (PVC), or any other suitable material, such as polytetrafluoroethylene (PTFE) or polyimide. The medication delivery tube  212  may also be composed of PVC, PTFE, or Polyimide material, and the needle portion  213  may be made of stainless steel hypotubing. 
         [0022]    Of course, it should be understood that a range of changes and modifications can be made to the preferred embodiments described above. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it be understood that it is the following claims, including all equivalents, which are intended to define the scope of this invention.