Abstract:
A method and system for shrinking dilatations of a body, removing excess, weak or diseased tissue, and strengthening remaining tissues of the lumen walls. A catheter is disposed near the dilatation and fixed in position by inflatable occlusion balloons. Body fluids present in the occluded dilatation are evacuated and treatment fluid is exuded under pressure into the dilatation. Pressure is maintained by the treatment fluid while energy is applied by the catheter to heat the treatment fluid, causing the lumen walls to absorb the treatment fluid. Additional energy is then applied so as to preferentially heat the lumen wall tissues which have absorbed the treatment fluid, while at the same time treatment fluid is circulated to cool the inner surface of the lumen walls. The dilatation is occluded, a saline solution is introduced and absorbed into the lumen-wall tissue in the occluded region of the dilatation and then heated by application of radio frequency (“RF”) or other energy in order to soften only the lumen-wall tissue of the dilatation, the dilatation is shrunk by application of a chilled saline solution and a vacuum, and additional RF or other energy is emitted to ablate, further shrink, and harden only the lumen-wall tissue of the dilatation, without destroying the inner surface of the lumen or other tissues of the body beyond the lumen walls, thereby promoting growth of epithelial cells.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to techniques for shrinking dilatations in the body by localized tissue modification. 
     2. Related Art 
     A dilatation is an abnormally enlarged or distended segment of an otherwise patent biological lumen or conduit, such as the gastrointestinal, genito-urinary, pulmonary, vascular, or other systems in the body. Dilatations may also occur at other places within the body, such as in the nervous system, the eyes, or the skin. The degree of enlargement, the length, and the significance of the dilatation may differ greatly between particular dilatations, and is responsive to the nature of the lumen subject to the dilatation. Various etiological factors might be responsible for the development or exacerbation of any particular dilatation; these may include, for example, blockage, stenosis, infection, inflammation, trauma (whether external, internal, or surgical), or cancer. One or more of these factors causes the affected lumen to enlarge, expand or distend, with consequential compromise of the function of the lumen and increased danger of rupture of the lumen. 
     Treatment of dilatations is aimed at restoration of normal intraluminal diameter and strengthening of the lumen walls. Because of the presence of abnormal or diseased tissue at the dilatation, surgical treatment by endoscopic or by open surgical techniques often poses extra difficulties and has significant morbidity. Moreover, because the tissue of the lumen wall at the dilatation is already diseased, it often generates further scarring and fibrosis when it heals after surgery, which can lead to recurrence of the dilatation. 
     Accordingly, it would be advantageous to provide a method and system for treatment of dilatations, such as for example vascular aneurysms, which uses existing tissue, which promotes healing of existing tissue, and which helps to prevent recurrence of the dilatation. This advantage is achieved in an embodiment of the invention whereby the dilatation is occluded, a saline solution is introduced into the occluded region and perfused into the lumen-wall tissue of the occluded region, radio frequency (“RF”) or other energy is emitted controllably to heat and soften only the lumen-wall tissue perfused with saline solution in the occluded region of the dilatation, the dilatation is shrunk by application of a chilled saline solution and a vacuum, additional RF or other energy is emitted to ablate, further shrink, and harden only the lumen-wall tissue perfused with saline solution in the occluded region of the dilatation, all without destroying the inner surface of the lumen or other tissues of the body beyond the lumen wall and thereby promoting growth of epithelial cells in the lumen wall. 
     It would be further advantageous to provide a method and system for treatment of distended, engorged, inflamed or infected tissue such as cysts, gangrenous tissue, necrotic tissue or tumors, including shrinking, reducing, destroying and removing such tissue, from any system of the body including the cardiovascular system, the lymphatic system, the cardiopulmonary system, the gastrointestinal system (head and neck, esophagus, stomach, intestines, colon, rectum), the urogenital system, the nervous system, particular organs such as the kidney or prostate, retinal lesions and skin lesions. 
     SUMMARY OF THE INVENTION 
     The invention provides a method and system for treatment of dilatations using a catheter for precise application of RF energy to subsurface lumen-wall tissue to reduce the diameter of an enlarged portion of any sphincter or lumen of the body. The catheter is introduced into a lumen of the body and directed to the vicinity of the dilatation to be treated, the position of the catheter is fixed and the dilatation is occluded between two inflatable balloons, and a first saline solution is introduced into the occluded region at a temperature and pressure sufficient to perfuse the saline solution into tissue of the lumen wall in the occluded region; the first saline solution is then exchanged for a chilled saline solution, a vacuum is applied, and RF energy is emitted at a frequency which is absorbed more readily by the lumen-wall tissue which has absorbed the first saline solution, thereby shrinking, ablating and hardening the lumen-wall tissue of the dilatation without effecting either the mucosal surface of the lumen or other tissues of the body beyond the lumen walls, to modify the lumen to within the range of normal and maintain the normal diameter of the lumen and prevent reformation of the dilatation during a healing period. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a catheter inserted into a lumen of the body and located in a dilatation of that lumen, with two occluding balloons and an optional intermediate treatment balloon inflated. 
         FIG. 2  is a cross-section of the catheter with the sides of the three inflated balloons cut away, showing additional features of the catheter tip assembly. 
         FIG. 3  shows a mesh of direct contact bipolar electrodes that have been expanded by and about the optional intermediate treatment balloon. 
         FIG. 4  shows a catheter tip assembly with monopolar ring electrodes that can be used with or without the optional intermediate treatment balloon. 
         FIG. 5  shows a catheter tip assembly with bipolar ring electrodes that can be used with or without the optional intermediate treatment balloon. 
         FIG. 6  shows a flow chart of a method of operation for the catheter. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, a preferred embodiment of the invention is described with regard to preferred structures and process steps. Those skilled in the art would recognize after perusal of this application that embodiments of the invention can be implemented using structures and process steps adapted for treatment of particular regions of the body, and that implementation of the process steps and structures described herein would not require undue experimentation or further invention. 
     System Elements 
     Catheter and Tip Assembly 
     A catheter  100  includes a tip assembly  101  and a multi-lumen tube  102  coupled thereto. The tip assembly  101  comprises a generally prolate spheroid with a long axis  103 . The tip assembly  101  includes a proximal end  109  and a distal end  110 , with the proximal end  109  coupled to the multi-lumen tube  102  for coupling control signals, energy and fluids between the tip assembly  101  and a control system (not shown). The tip assembly  101  is disposed in a dilatation  113  of a lumen  104  of the body of a patient with the long axis  103  approximately parallel to lumen walls  105 . 
     In a preferred embodiment, the dilatation  113  in the lumen  104  may comprise an aneurysm in a blood vessel. However, in alternative embodiments, the dilatation  113  may comprise any sphincter or lumen of the body. 
     In alternative embodiments, the tip assembly  101  may comprise another shape, such as curved or needle-like disposed for fitting within a particular body cavity, for avoiding a particular body structure, or for adaptation to a particular body structure. For example, the tip assembly  11  may comprise a curved, needle-like shape adapted to a surface curvature of an eyeball so that the tip assembly  101  can be inserted under an eyelid. 
     In a preferred embodiment, the catheter tube  102  comprises a relatively inert and nonconducting substance such as woven dacron. However, in alternative embodiments, the catheter tube  102  may comprise other relatively inert and nonconducting materials such as kevlar, nylon, or plastic, or combinations thereof. 
     In a preferred embodiment, the tip assembly  101  may include one or more marker elements preferably disposed at or near the distal end  110  of the tip assembly  101  and/or at or near the proximal end  109  of the tip assembly  101 , which are noticeable using fluoroscopy or ultrasound or other suitable means. With appropriate x-ray or fluoroscopy equipment, a radiologist or surgeon can position the catheter  100  relative to the dilatation  113  without any requirement for a camera or other optical equipment disposed in or near the dilatation  113 . However, in alternative embodiments, such a camera or other optical equipment may be included. 
     The tip assembly  101  includes at least one port  111 , from which a treatment fluid  112  may flow out of the tip assembly  101  and into or near the dilatation  113 , and at least one suction port  114 . In a preferred embodiment, the port  111  and suction port  114  are further disposed to comprise a fluid circulation system, wherein at least one port  111  is a fluid outlet port and at least one suction port  114  is a fluid inlet port. The fluid circulation system is disposed for circulating fluid in the region of the dilatation  113  near the catheter  100 , such as for delivering fluid for cooling the region and for removing other fluid for aspirating the region. 
     In a preferred embodiment, the port  111  is disposed for delivering substantially equal amounts of treatment fluid  112  in all directions from the tip assembly  101 . However, in alternative embodiments, the port  111  may be disposed for delivering differing amounts of treatment fluid  112  in an asymmetrical pattern near the tip assembly  101 , either by altering the shape of a single port  111  or by including a plurality of ports  111 . For a first example, while in a preferred embodiment there could be a single port  111 , alternatively there could be a plurality of ports  111  each substantially the same size but with a variable number of ports  111  located in various locations about the tip assembly  101 , and further alternatively there may be ports  111  of substantially different sizes. For a second example, while in a preferred embodiment the ports  111  are each open at all times, in alternative embodiments, they may be subject to a microscopic mechanical device or other technique for closing some or all of them at selected times. 
     Preferably, the ports  111  are also disposed for removing fluids from the lumen  104 . In some embodiments, the ports  111  may handle all fluid delivery and removal during treatment, and no suction ports  114  are needed. All of the ports  111  may be coupled to a single lumen in the catheter tube  102 , or some ports  111  may be coupled to one lumen and other ports  111  coupled to another lumen in the catheter tube  102 . Preferably, movement of treatment fluid  112  through the ports  111  is controllable so that, according to the needs of a treatment regimen, at a given time all of the ports  111  may deliver treatment fluid  112 , all of the ports  111  may remove treatment fluid  112  and/or other fluids, or some ports  111  may deliver treatment fluid  112  while other ports  111  simultaneously remove treatment fluid  112  and/or other fluids. 
     In an alternative embodiment, separately controllable suction ports  114 , coupled to a lumen in the catheter tube  102 , may also be located on an exterior surface of the tip assembly  101 , and in combination with the ports  111  may comprise a fluid circulation system. 
     The tip assembly  101  may also include at least one temperature sensor  115  and at least one pressure sensor  116 , both preferably disposed at or near the surface of the tip assembly  101 . The sensors are coupled using the catheter tube  102  to a control system (not shown) and to an operator presentation device (not shown). The sensors provide signals to the control system for feedback control, and to the operator presentation device for presenting information to an operator. 
     In a preferred embodiment, the temperature sensor  115  comprises a plurality of temperature sensors, such as thermistors or thermocouples, and the control system provides feed-back control to maintain various temperatures selected by the operator. In a preferred embodiment, the operator presentation device comprises a temperature reporting gauge. However, it would be clear to those skilled in the art that other and further sensor signals, feedback control, and presentation signals would be useful, and are within the scope and spirit of the invention. 
     In a preferred embodiment, the pressure sensor  116  comprises a plurality of pressure sensors, and the control system provides feedback control to maintain various pressures selected by the operator. In a preferred embodiment, the operator presentation device comprises a pressure reporting gauge. However, it would be clear to those skilled in the art that other and further sensor signals, feedback control, and presentation signals would be useful, and are within the scope and spirit of the invention. 
     In alternative embodiments, the tip assembly  101  may be fitted with other and further equipment. Such equipment may include a camera or other light-gathering device, either to for aiding a surgeon in manipulating the catheter  100  (e.g., maneuvering the tip assembly  101  to reach the dilatation  113 ), or for photographically recording the action of the catheter  100  and associated equipment; a laser or other device for ablating or reducing obstructions; or other equipment. Coupling cameras or other light-gathering devices, or lasers or other ablating or reducing devices, to catheters  100  is known in the art of medical devices. 
     Treatment Fluid 
     As used herein, the term “treatment fluid” is used generically to mean and refer to any fluid which can act as an electrolyte. In the preferred embodiment, the treatment fluid  112  is a saline solution. However, in alternative embodiments, the treatment fluid  112  may be collagen, a collagenous fluid, or any other fluid which is readily absorbed by the tissue of the lumen walls  104  and which readily absorbs RF energy. In further alternative embodiments, the treatment fluid  112  may comprise medicine, water, or a fluid which is relatively inert and non-bioreactive but heat conductive. 
     Balloons 
     The tip assembly  101  also includes a first occluding balloon  106  preferably disposed at or near a proximal end  109  of the tip assembly  101 , and a second occluding balloon  107  preferably disposed at or near the distal end  110  of the tip assembly  101 . The occluding balloons  106  and  107  are disposed so that when inflated, and in combination with the body of the tip assembly  101 , they form a gas-tight or fluid-tight seal against the lumen walls  105  and seal off the portion of the dilatation  113  to be treated from other portions of the lumen  104 . The occluding balloons  106  and  107  preferably comprise ring-shaped annular balloons; however, in an alternative embodiment, the distal occluding balloon  107  may comprise a spherical or ellipsoidal balloon disposed at the distal end  110  of the tip assembly  101  in such a manner that when inflated it surrounds the catheter  100  and makes a gas-tight or fluid-tight seal against the lumen walls  104 . 
     In a preferred embodiment, both occluding balloons  106  and  107  are coupled to a single lumen in the catheter tube  102  disposed for delivery of an inflation fluid from a source (not shown). In an alternative embodiment, the occluding balloons  106  and  107  are coupled to separate lumina in the catheter tube  102  disposed for delivery of inflation fluid from sources (not shown), so that the occluding balloons  106  and  107  may be inflated independently of each other. 
     In a preferred embodiment, at least one occluding balloon  106  or  107  is disposed to anchor the catheter  100  at a selected location within the lumen  104 ; alternatively, both occluding balloons  106  and  107  may be to anchor the catheter  100 . The occluding balloons  106  and  107  when inflated prevent the catheter  100  from being expelled from the body in like manner as the operation of a Foley catheter. However, in alternative embodiments, the balloon used to anchor the catheter  100  may comprise either occluding balloon  106  or  107 , or an additional or alternative balloon which is disposed solely or primarily for the purpose of anchoring the catheter  100  into the selected location, again in like manner as the operation of a Foley catheter. 
     The tip assembly  101  may also include a third balloon  108  (hereinafter referred to as a “treatment balloon  108 ”), preferably located intermediately between the occluding balloons  106  and  107 , which is inflated using a lumen in the catheter tube  102  for delivery of treatment fluid  112  from a source (not shown) through at least one port  111 . In a preferred embodiment, the treatment balloon  108  is disposed so that when inflated its surface physically comes into contact with the tissue of the lumen walls  105  which comprise the dilatation  113 . The treatment balloon  108  may also include a porous, microporous, or semiporous membrane through which the treatment fluid  112  may flow. 
     In an embodiment wherein a treatment balloon  108  is used, the suction ports  114  are preferably located between the outside surface of intermediate treatment balloon  108  and the outside surfaces of the occluding balloons  106  and/or  107 , so that fluid is drawn into the suction ports  114  from the occluded region of the lumen  104 . Preferably, the suction ports  114  may be used either separately or at the same time that treatment fluid  112  is delivered from the ports  111  into the treatment balloon  108 . 
     Electrodes 
     The catheter  110  also includes at least one electrode, described in more detail below, preferably disposed on the tip assembly  101  between the occluding balloons  106  and  107 . The electrodes are coupled using the catheter tube  102  to a power source  120 . The power source  120  provides energy to the electrodes, which emit that energy into the lumen walls  105  of the dilatation  113  which have been perfused with the treatment fluid  112  so as to affect the lumen walls  105  of the dilatation  113 . 
       FIG. 3  shows a first aspect of the preferred embodiment using direct contact bipolar electrodes  123  to emit RF energy for heating, ablation and/or shrinkage of the dilatation  113 . In the first aspect of the preferred embodiment, a plurality of bipolar electrodes  123  are distributed more or less equidistant from each other and disposed so that when the treatment balloon  108  is inflated the electrodes  123  are put in direct contact with the inner surface of the lumen walls  105  in the occluded region of the dilatation  113 . In a preferred embodiment, the electrodes  123  are disposed on an expandable conductor mesh  122  surrounding around the treatment balloon  108 . In an alternative embodiment, the conductor mesh  122  and electrodes  123  may be disposed in or near the surface of the treatment balloon  108 . 
       FIG. 4  shows a second aspect of the preferred embodiment using monopolar ring electrodes  124  to emit RF energy for heating, ablation and shrinkage of the dilatation  113 . In the second aspect of the preferred embodiment, a plurality of monopolar ring electrodes  124  are disposed repeatedly on or near the surface of the tip assembly  101  between its proximal end  109  and distal end  110 . 
       FIG. 5  shows a third aspect of the preferred embodiment using bipolar ring electrodes  125  to emit RF energy for heating, ablation and shrinkage of the dilatation  113 . In the third aspect of the preferred embodiment, a plurality of bipolar ring electrodes  125  are disposed repeatedly on or near the surface of the tip assembly  101  between the proximal end  109  and the distal end  110  of the tip assembly  101 . 
     In alternative embodiments, many configurations of electrodes and sensors  116  may operate under processor control to achieve such effects. In a first example, distances between pairs of ring electrodes  124  may be adjusted, either during manufacture, dynamically before use of the catheter tip  101 , or otherwise. In a second example, the sensors  116  may be effective to measure other dynamic features of the treatment fluid  112  and lumen-wall tissue of the dilatation  113 , such as a localized electrical impedance, a localized fluid flow, or some combination thereof. In a third example, the processor may be effective to control other features of the RF energy, such as a pulse shape or duty cycle of a pulse for RF energy delivery, a frequency for RF energy delivery, a time duration for pulses or time duration between pulses, an order for selection of individual ring electrodes  120  for delivery of RF energy, or some combination thereof. 
     Energy Source 
     Electrodes, as described above, are coupled to a power source  120  using a conductor  121  in the catheter tube  102 . The conductor  121  is preferably insulated so as to avoid electrical coupling with the catheter tube  102 , the treatment fluid  112  or the lumen walls  105 . The power source  120  provides energy to the electrodes, which emit that energy into the treatment fluid  112  and tissue of the lumen walls  105  in the occluded region of the dilatation  113 . 
     As used herein, the term “RF energy” is used generically to mean and refer to any means for heating the treatment fluid  112  and/or tissue of the lumen walls  105 , broadly including the application of RF energy in a wide range of frequencies, such as the 300 to 700 MHz frequency described herein as well as other microwave frequencies and other frequencies. Those skilled in the art would recognize, after perusal of this application, that other means for heating the treatment fluid  112  and lumen walls  105  may be applied. 
     For example, where the treatment fluid  112  is a photosensitive substance, the means for heating may comprise light. In such an alternative embodiment, the light may be delivered by a laser, light-emitting diode, or other light source coupled to the tip assembly  101 . 
     The energy source  120  is preferably located outside the lumen  104  and outside the body. In a preferred embodiment, the RF energy source  120  generates a continuous or pulsed waveform, preferably a sinusoidal waveform or a square waveform, such as an RF energy generator available as a standard product from Radionics Valley Laboratories, a division of Pfizer, Inc. 
     In a preferred embodiment, the RF energy source  120  supplies about 50 watts of power, distributed to all of the electrodes  123  collectively, and pulsed in a round-robin fashion among the electrodes  123  so as to equally distribute the delivered energy to all positions along the tip assembly  101 . 
     The RF energy source  120  may comprise a processor which is responsive to signals from the sensors  116  and to a computed or expected amount of the treatment fluid  112  and lumen wall tissue  105  to be treated. The processor computes an effective amount of time and RF energy to deliver to each individual electrode, and controls delivery of RF energy to each individual electrode so as to deliver RF energy to localized points of the treatment fluid  112  and lumen wall tissues  105  which have absorbed it. 
     Method of Operation 
       FIG. 6  shows a flowchart for a method of operation of the catheter  100 . 
     A method  200  of operation for the catheter  100  comprises a sequence of steps between the flow points  201  and  220 . In the preferred embodiment, the method  200  is carried out using the catheter  100 , as well as other and further equipment which would be clearly deemed necessary or desirable by those skilled in the art. 
     At a flow point  201 , the catheter  100  is ready for use to treat dilatation  113 . 
     At a step  202  in a preferred embodiment, the catheter  100  is inserted into the lumen  104  of a patient at a natural body orifice such as the mouth, anus or urethra. However, in alternative embodiments the catheter  100  may be inserted into a blood vessel near a body surface, such as the jugular vein or carotid artery or other blood vessel in the neck, or may be inserted into the patient at a body structure which is made available during surgery or by virtue of a wound; the body structure may comprise a blood vessel, tubular organ, the lymphatic system, a sinus cavity or other ear/nose/throat structure, the intestines, the urethra, a mass of tissue such as a cyst or a fatty deposit, or some other body structure. 
     At a step  203 , the catheter  100  is maneuvered by an operator (not shown) to a position in the lumen  104  approximately adjacent to the dilatation  113  while the operator views the position of the catheter  100  using fluoroscopy, ultrasound, or other suitable means. 
     At a step  204 , the occluding balloons  106  and  107  are inflated and the dilatation  113  sealed off from the remainder of the lumen  104 . 
     At a step  205 , the treatment balloon  108  is inflated with treatment fluid  112  exuded from ports  111  while simultaneously any body fluids in the occluded dilatation  113  are removed by suctioning them into suction ports  114  disposed on the tip assembly  101  between the occluding balloons  106  and  107  and coupled to a suction lumen in the catheter tube  102 . Body fluids are thus removed from the occluded portion of the dilatation  113  by the dual action of suction outside the treatment balloon  108  and pressure within it. Inflation of the treatment balloon  108  and suction of body fluids continues until all body fluids have been removed from the occluded dilatation  113  and the outer surface of the treatment balloon  108  has been brought into contact with the inner surface of the lumen wall  105  of the dilatation  113 . 
     At a step  206 , RF energy is emitted by electrodes in the catheter tip assembly  101  at a selected frequency and power level effective to heat the treatment fluid  112  to a temperature at which it is readily absorbable into the tissue of the lumen walls  105 . 
     At a step  207 , the treatment fluid  112  in the treatment balloon  108  is pressurized to a selected pressure, effective to cause the treatment fluid  112  to exude through the microporous membrane of the treatment balloon and come into contact with the lumen walls  105 . 
     At a step  208 , the heated treatment fluid  112  is suffused into and absorbed by the tissues of the lumen walls  105 . 
     At a step  209 , additional RF energy is emitted by the electrodes in the catheter tip assembly  101  at a selected frequency and power level effective to preferentially heat tissues of the lumen walls  105  which have absorbed the treatment fluid  112 . Optionally, while tissues of the lumen walls  105  are being heated, cool treatment fluid  112  may be circulated in the occluded portion of the lumen  104  by exuding it from ports  111  and suctioning it into suction ports  114 , in order to minimize heating and damage of cells lining the inner surface of the lumen walls  105 . Heating of lumen wall tissues  105  continues until they have been softened. 
     At a step  210 , the heated treatment fluid  112  is removed from the occluded portion of the dilatation  113  via the suction ports  114  and the occluded portion of the dilatation is filled with chilled treatment fluid  112  via the ports  111 . 
     At a step  212 , the dilatation  113  is contracted by application of the chilled treatment fluid  112  and by application of a vacuum via the suction ports  114  so that dilatation  113  shrinks to a diameter within a normal diameter range for the lumen  104 . 
     At a step  213 , additional RF energy may be emitted by the electrodes in the catheter tip assembly  101  at a selected frequency and power level effective to ablate tissues of the lumen walls  105 , while chilled treatment fluid  112  is circulated by exuding it in via the ports  111  and suctioning it out via the suction ports  114  in order to minimize heating and damage of cells lining the inner surface of the lumen walls  105  and remove detritus of ablation. 
     At a step  214 , the tissues of the lumen walls  105  are hardened in the contracted condition by further application of RF energy and circulation of chilled treatment fluid  112 . 
     At a step  215 , the occluding balloons  106  and  107  and the treatment balloon  108  are deflated. 
     At a step  216 , the catheter  100  is removed from the body of the patient. 
     At a flow point  220 , the dilatation has been treated and should be in a condition for normal operation. 
     ALTERNATIVE EMBODIMENTS 
     Although preferred embodiments are disclosed herein, many variations are possible which remain within the concept, scope, and spirit of the invention, and these variations would become clear to those skilled in the art after perusal of this application.