Abstract:
Methods and systems for resecting and debulking prostatic tissue to utilize a shaft carrying an energy source. The shaft is anchored by a balloon or other structure expanded in the bladder, and the energy source is capable of directing ablative energy radially outwardly from the urethra, where the energy source will be moved in order to remove a pre-defined volume of prostatic tissue.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional application 60/883,097 (Attorney Docket No. 026918-000100US—formerly 022237-001400US), filed on Jan. 2, 2007, the full disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to medical methods and devices. In particular, the present invention relates to methods and devices for applying energy to the urethra to achieve volumetric tissue reduction. 
         [0004]    A number of medical conditions affect the male urethra causing a variety of symptoms including painful or difficult urination, a swollen prostate, blood in the urine, lower back pain, and the like. Some of these conditions, such as prostatitis, are bacterial infections which can be treated with antibiotics and other drugs. Other conditions, however, such as benign prostatic hyperplasia (BPH) and prostatic carcinoma, result in enlargement of the prostate and obstruction of the urethra, sometimes leading to complete loss of bladder function. 
         [0005]    Both BPH and prostatic cancer require treatments which remove or shrink tissue in the prostate surrounding the urethra. Common treatments include transurethral resection of the prostate (TURP) where a resectoscope is placed in the urethra and used to remove excess prostatic tissue. Another procedure, referred to as transurethral incision of the prostate (TUIP), relies on cutting muscle adjacent to the prostate to relax the bladder opening to relieve difficulty in urination. More recently, a procedure referred to as transurethral needle ablation (TUNA) has been introduced where a needle is advanced through the urethra into the prostate and used to deliver energy, such as microwave, radiofrequency, or ultrasound energy, to reduce the size of the prostate, again relieving pressure on the urethra. Laser ablation using transurethral optical fibers also finds use. 
         [0006]    While generally successful, none of these methods are adequate to treat all patients and all conditions. In particular, patients having severe tissue intrusion into the urethral lumen resulting from BPH or prostatic cancer are difficult to treat with minimally invasive protocols which rely on tissue shrinkage rather than resection. Thus, many of these patients will eventually require conventional surgical resection. 
         [0007]    For these reasons, it would be desirable to provide minimally invasive methods and devices which provide for enlarging the luminal area and/or volumetric resection of tissue surrounding the urethra. It would be particularly desirable if such methods and devices provided for removal or destruction of such tissues surrounding the urethra where the removal or destruction products can be removed from the lumen to relieve pressure on the urethra, even where large volumes of tissue have been removed. Alternatively or additionally, the methods and devices should provide for anchoring of the treatment device relative to the urethra in order to provide a stable platform for treatment protocols which do not require visualization. Methods and devices for performing such protocols should present minimal risk to the patient, should be relatively easy to perform by the treating physician, and should allow for alleviation of symptoms with minimal complications even in patients with severe disease. At least some of these objectives will be met by the inventions described below. 
         [0008]    2. Description of the Background Art 
         [0009]    Use of a transurethral endoscope for bipolar radiofrequency prostate vaporization is described in Boffo et al. (2001)  J. Endourol.  15:313-316. Radiofrequency discharge in saline solutions to produce tissue-ablative plasmas is discussed in Woloszko et al. (2002)  IEEE Trans. Plasma Sci.  30:1376-1383 and Stalder et al. (2001)  Appl. Phys. Lett.  79:4503-4505. Air/water jets for resecting tissue are described in Jian and Jiajun (2001)  Trans. ASME  246-248. US2005/0288639 described a needle injector on a catheter based system which can be anchored in a urethra by a balloon in the bladder. U.S. Pat. Nos. 6,890,332; 6,821,275; and 6,413,256 each describe catheters for producing an RF plasma for tissue ablation. Other patents and published applications of interest include: U.S. Pat. Nos. 7,015,253; 6,890,332; 6,821,275; 6,413,256; 6,378,525; 6,296,639; 6,231,591; 6,217,860; 6,200,573; 6,179,831; 6,142,991; 6,022,860; 5,994,362; 5,872,150; 5,861,002; 5,817,649; 5,770,603; 5,753,641; 5,672,171; 5,630,794; 5,562,703; 5,322,503; 5,116,615; 4,760,071; 4,636,505; 4,461,283; 4,386,080; 4,377,584; 4,239,776; 4,220,735; 4,097,578; 3,875,229; 3,847,988; US2002/0040220; US2001/0048942; WO 93/15664; and WO 92/10142. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Methods, devices, and systems according to the present invention provide for intraluminal delivery of energy, to ablate or resect tissue surrounding a urethra. The present invention is particularly intended for treating benign prostatic hyperplasia (BPH) and prostatic carcinoma, both of which can result in compression and partial or total occlusion of the urethra. Treatments comprise positioning an energy source within the urethra and directing energy radially outwardly from the energy source toward the urethral wall within the prostate. The energy source will usually be moved relative to the urethra to remove a pre-defined volume of prostate tissue surrounding the urethral lumen in order to partially or fully relieve the compression and/or obstruction. In other embodiments, however, the therapy may comprise mechanical, thermal, acoustic or vibrational, cryotherapy or other forms of treatment for BPH and other conditions. Optionally, the treatments of the present invention may be combined with chemotherapy and other forms of drug delivery, as well as treatment with external X-ray and other radiation sources and administration of radiopharmaceuticals comprising therapeutic radioisotopes. For example, one or more drugs may be combined with the saline or other fluid which is used for energy delivery. The combination liquid/gas delivery can be used to both resect tissue and wash the tissue away while leaving intra-prostatic blood vessels, capsule, and sphincter muscle undamaged. Thus, benefits of the high pressure liquid/gas energy source include limited bleeding with reduced or no need for cauterization and decreased risk of perforating or otherwise damaging the capsule of sphincter muscles. Alternatively, the device which is used to position the energy source can be utilized to separately deliver a desired chemotherapeutic or other drug (as just set forth), either before, during, or after energy treatment according to the present invention. While the present invention is specifically directed at transurethral treatment of the prostate, certain aspects of the invention may also find use in the treatment of other body lumens, organs, passages, tissues, and the like, such as the ureter, colon, esophagus, lung passages, bone marrow, and blood vessels. 
         [0011]    Thus, in a first aspect of the present invention, methods for resecting and removing prostate tissue comprise positioning an energy source within the urethra and directing energy radially outwardly from the energy source toward a wall of the urethra within the prostate. The energy source is then moved relative to the urethra to remove a pre-defined volume of tissue surrounding the lumen. In a particular aspect of the present invention, the method further comprises expanding an anchor within the bladder at the distal end of the urethra. The energy source is then positioned and moved relative to the anchor to assure that the treatment is properly directed to prostatic tissue. The use of the anchor is particularly advantageous since it allows the procedures to be performed without endoscopic, fluoroscopic, or other imaging. The methods of the present invention, of course, do not exclude such imaging, but rather permit the methods to be performed when desired without further imaging. 
         [0012]    Usually, the energy source and the anchor will be mounted on a common catheter assembly, more typically on a single shaft. Thus, the catheter assembly or shaft may be maintained in a fixed or immobilized position within the urethra by either applying a tension which engages the anchor against the bladder wall, or preferably by expanding the anchor fully within the bladder to reduce the risk that the catheter assembly or shaft can be accidentally dislodged. 
         [0013]    The energy source can be any one or a combination of various conventional energy sources which can be used to resect or ablate tissues. A first exemplary energy source comprises high pressure fluids, such as water, saline, liquid therapeutic agent, or the like. The high pressure fluid is often a combination of a liquid and gas, such as water and air, and can be delivered radially outwardly in one or more fluid streams which impinge directly against the urethral wall and prostatic tissue to resect or debulk the tissue. The fluid stream(s) may be directed at a generally perpendicular or normal angle relative to a catheter assembly or shaft, and may also be directed at other angle(s), typically in the range from 10° to 90°, more typically from 45° to 90°, relative to the shaft or catheter assembly which carries the port or ejector used to deliver the fluid(s) including, for example, anesthetics, antibiotics, anti-inflammatories, anti-neoplastics, tissue-specific growth factors, anti-growth factors, hormones, anti-hormones, vasodilators, vitamins, proteins, and the like. 
         [0014]    The energy source may also deliver laser energy used to ablate tissue. The laser energy will usually be delivered by an optical waveguide or fiber bundle carried within a catheter assembly or shaft which is introduced through the urethra. The laser energy can then be directed radially outwardly either by deflecting the shaft and/or by using a mirror to reflect the energy. The mirror may optionally have a surface which focuses or defocuses the energy in a desired manner as it is delivered to the prostatic tissue. 
         [0015]    A third suitable energy source comprises an electrically conductive fluid which carries radiofrequency current, optionally generating a plasma of the conductive fluid. One or more streams of such electrically conductive fluids may be directed outwardly through ceramic nozzles or other distribution elements. 
         [0016]    A fourth energy source comprises an electrode adapted to deliver radiofrequency energy. The electrode will have a deflected or deflectable distal end which can be directed radially outwardly from a catheter assembly or shaft which carries the electrode into the urethra. The tip or other surface of the electrode can thus be engaged against the urethral wall and prostatic tissue in order to deliver ablative radiofrequency energy into the tissue. 
         [0017]    The methods of the present invention may further comprise associated steps and processes to assist in the tissue resection and ablation. In order to gain a working space within the urethra, the methods may further comprise introducing a pressurized gas to expand (insufflate) the urethra lumen prior to or while directing the energy radially outwardly into the prostatic tissue. Further optionally, the ablation or resection products may be aspirated from the urethra, typically through a lumen in the catheter assembly or shaft used to deliver the energy source. In combination with aspiration, the urethra may also be flushed with saline or other fluid to assist in removing the ablation or resection products. Usually, both flushing and aspiration will be performed using lumens in the same catheter assembly or shaft which has been used to position the energy source. 
         [0018]    The energy source will be moved in a pre-defined manner relative to the anchored shaft or urethra in order to selectively treat the prostatic tissue. Typically, the energy source will be moved to cover and treat a cylindrical volume of prostatic tissue surrounding the urethra. In such cases, the energy source will typically be rotated and/or axially translated within the urethra so that the energy is uniformly delivered into the urethral wall. Alternatively, the energy source may be scanned to a non-cylindrical and optionally non-symmetric region within the urethra which has been targeted for treatment. Various combinations of rotation, axial translation, rotational oscillation, and axial oscillation may be used. 
         [0019]    In a separate aspect of the present invention, methods for treating a prostate comprise advancing a shaft through a urethra. An anchor on the shaft is expanded in a bladder to stabilize the shaft in the urethra, that is to fix the position relative to the urethral wall. The treatment device on the shaft is then activated to enlarge the urethra and/or debulk the prostate, where the position of the treatment device is fixed by the anchor. Usually, the anchor comprises a balloon which is inflated within the bladder, typically being inflated to fully occupy the entire volume of the urethra so that the risk of dislodgement is reduced. Actuating the treatment device may comprise use of any one of the energy sources described above, broadly including applying mechanical, vibrational, thermal, optical, and/or electrical energy to the prostatic tissue from the stabilized shaft. Usually, the treatment device will be moved relative to the shaft to treat a pre-defined surface region of the urethra, where the pre-defined surface region is usually cylindrical but may be non-cylindrical and non-symmetric as also described above. Typically, the treatment device emits a stream or circumferential band of energy, where movement comprises at least axial translation and/or axial oscillation. Usually, movement will further comprise rotation and/or rotational oscillation. 
         [0020]    In addition to the methods described above, the present invention also provides prostate resection devices comprising a shaft, an expandable anchor, and at least one energy source. The shaft has a proximal end and a distal end. The expandable anchor is positioned on the shaft near its distal end and is adapted for anchoring within the bladder. The at least one energy source is also on the shaft and is spaced proximally of the anchor by a distance selected to position the energy source within a desired region of the urethra, typically within the prostate, when the anchor is positioned in the bladder. Thus, the energy may be delivered radially outwardly from the energy source selectively into the target prostate tissue without the need for imaging or other positioning methods or apparatus. 
         [0021]    The prostate resection devices of the present invention may further comprise various lumens in the shaft for performing supplemental portions of the procedure. For example, the shaft may comprise one or more lumens for delivering a gas or fluid to pressurize and enlarge (insufflate) the urethra surrounding the energy source. One or more additional lumens may be provided for aspirating the urethra to remove ablation products and/or for delivering fluids to flush the urethra to remove ablation or resection products. The shaft will be adapted for delivery in a retrograde direction into the male urethra, typically having a width in the range from 1 mm to 10 mm and a length in the range from 15 cm to 25 cm. 
         [0022]    The prostate resection devices of the present invention may comprise any of the various energy sources described above. Usually, the energy source will be movable relative to the shaft to allow for selectively directing energy at different regions of the prostate. More typically, the energy source may be translated, rotated, translationally oscillated, and/or rotationally oscillated relative to the shaft. Exemplary energy sources comprise a high pressure fluid ejector, such as a nozzle or other port connected to additional lumen(s) in the shaft, a laser energy source, such as an optical fiber optionally combined with a mirror for reflecting the laser energy, a conductive fluid source in combination with a radiofrequency energy source, and/or an electrode that can be positioned against the urethral wall to deliver radiofrequency energy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a schematic illustration of a device suitable for performing intraurethral prostatic tissue debulking in accordance with the principles of the present invention. 
           [0024]      FIGS. 2A-2D  illustrate use of the device of  FIG. 1  in performing prostatic tissue debulking. 
           [0025]      FIG. 3  illustrates a specific prostatic tissue treatment device incorporating the use of a radiofrequency saline plasma for performing prostatic tissue debulking. 
           [0026]      FIG. 4  illustrates an energy source suitable for use in the devices of the present invention, wherein the energy source delivers a high pressure fluid for tissue resection. 
           [0027]      FIG. 5  illustrates an energy source suitable for use in devices of the present invention, wherein the energy source comprises a deflected optical waveguide for delivering laser energy to the prostatic tissue. 
           [0028]      FIG. 6  illustrates a device similar to that shown in  FIG. 5 , except the optical waveguide directs laser energy at a mirror which laterally deflects the laser energy. 
           [0029]      FIG. 7  illustrates an energy source suitable for use in the devices of the present invention, wherein the energy source comprises a laterally projecting electrode which can engage the urethral wall and prostatic tissue to deliver radiofrequency energy for tissue ablation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Referring to  FIG. 1 , an exemplary prostatic tissue debulking device  10  constructed in accordance with the principles of the present invention comprises a catheter assembly generally including a shaft  12  having a distal end  14  and a proximal end  16 . The shaft  12  will typically be a polymeric extrusion including one, two, three, four, or more axial lumens extending from a hub  18  at the proximal end  16  to locations near the distal end  14 . The shaft  12  will generally have a length in the range from 15 cm to 25 cm and a diameter in the range from 1 mm to 10 mm, usually from 2 mm to 6 mm. The shaft will have sufficient column strength so that it may be introduced upwardly through the male urethra, as described in more detail below. 
         [0031]    The shaft will include an energy source positioned in the energy delivery region  20 , where the energy source can be any one of a number of specific components as discussed in more detail below. Distal to the energy delivery region, an inflatable anchoring balloon  24  will be positioned at or very close to the distal end  14  of the shaft. The balloon will be connected through one of the axial lumens to a balloon inflation source  26  connected through the hub  18 . In addition to the energy source  22  and the balloon inflation source  26 , the hub will optionally further include connections for an infusion/flushing source  28 , an aspiration (a vacuum) source  30 , and/or an insufflation (pressurized CO 2  or other gas) source  32 . In the exemplary embodiment, the infusion or flushing source  28  can be connected through an axial lumen (not shown) to one or more delivery ports  34  proximal to the balloon anchor  24  and distal to the energy delivery region  20 . The aspiration source  30  can be connected to a second port or opening  36 , usually positioned proximally of the energy delivery region  20 , while the insufflation source  32  can be connected to an additional port  38 , also usually located proximal of the energy delivery region. It will be appreciated that the locations of the ports  34 ,  36 , and  38  are not critical, and that the lumens and delivery means could be provided by additional catheters, tubes, and the like, for example including coaxial sleeves, sheathes, and the like which could be positioned over the shaft  12 . 
         [0032]    Referring now to  FIGS. 2A-2D , the prostatic tissue debulking device  10  is introduced through the male urethra U to a region within the prostate P which is located immediately distal to the bladder B. The anatomy is shown in  FIG. 2A . Once the catheter  10  has been positioned so that the anchoring balloon  24  is located just distal of the bladder neck BN ( FIG. 2B ) the balloon can be inflated, preferably to occupy substantially the entire interior of the bladder, as shown in  FIG. 2C . Once the anchoring balloon  24  is inflated, the position of the prostatic tissue debulking device  10  will be fixed and stabilized within the urethra U so that the energy delivery region  20  is positioned within the prostate P. It will be appreciated that proper positioning of the energy delivery region  20  depends only on the inflation of the anchoring balloon  24  within the bladder. As the prostate is located immediately proximal to the bladder neck BN and by spacing the distal end of the energy delivery region very close to the proximal end of the balloon, the delivery region can be properly located, typically having a length in the range from 0 mm to 5 mm, preferably from 1 mm to 3 mm. After the anchoring balloon  24  has been inflated, energy can be delivered into the prostate for debulking, as shown by the arrows in  FIG. 2 . Once the energy has been delivered for a time and over a desired surface region, the energy region can be stopped and the prostate will be debulked to relieve pressure on the urethra, as shown in  FIG. 2D . At that time, a flushing fluid may be delivered through port  34  and aspirated into port  36 , as shown in  FIG. 2D . Optionally, after the treatment, the area could be cauterized using a cauterizing balloon and/or stent which could be placed using a separate catheter device. 
         [0033]    Referring now to  FIGS. 3-7 , a number of representative energy delivery regions will be described. Referring now to  FIG. 3 , a first exemplary prostate resection device  110  constructed in accordance with the principles of the present invention comprises a shaft  112  having a proximal end  114  and a distal end  116 . A plurality of nozzles  118  are mounted on the shaft  112  at a location spaced proximally from the distal end  116  by distance in the range from 1 cm to 5 cm. The nozzles, which are typically ceramic cores capable of generating a plasma or ports capable of directing a radially outward stream of electrically conductive fluid, may be mounted on structure  120 , which allows the nozzles  118  to be moved radially outwardly, as shown in broken line in  FIG. 3 . An anchor  122 , shown as an inflatable balloon is mounted on the distal end  116  of the shaft  112  at a location between the nozzles  118  and the distal tip  124 . The expandable structure  122  will be capable of being expanded within the bladder to anchor the shaft  112  so that the nozzle array  118  lies within the prostate, as described in more detail below. The shaft  112  will include lumens, passages, electrically conductive wires, and the like, in order to deliver energy and materials from the proximal end  114  to the distal end  116  of the shaft. For example, an RF energy source  126  will be connected to the shaft  112 , usually to the nozzles  118 , in order to deliver RF energy to an electrically conductive fluid delivered from source  128  to the nozzles  118 , typically through a lumen within the shaft  112 . Other lumens, channels, or conduits will be provided in order to allow aspiration to a vacuum source  130  which is typically connected to one or more aspiration ports  132 . Other conduits may be provided within the shaft  112  in order to permit introduction of a flushing fluid, such as saline, from a source  134  to ports  136 . In other instances, it will be possible to connect the aspiration and flushing sources  130  and  134  to a common port so that aspiration and flushing may be conducted sequentially rather than simultaneously. Further optionally, internal lumens, conduits, or the like, may be provided in order to connect a source of insufflation  140  to one or more insufflation ports  142  on the shaft in the region of the array  118 . Finally, internal lumens, conduits, or the like, may be provided for connecting balloon  122  to a balloon inflation source  144 . 
         [0034]    As shown in  FIG. 4 , an exemplary energy delivery region  20  can be formed by a high pressure nozzle  200  which is carried on a delivery tube  202  which is disposed within the shaft  12 . Carrier tube  202  may be axially translated as shown by arrow  204  and/or rotated as shown by arrow  206  so that the high pressure stream  208  emanating from the nozzle  200  can be scanned or rastered over all or a selected portion of the urethra within the prostate. Specific pressures and other details for such high pressure water treatment are described, for example, in Jian and Jiajun, supra. 
         [0035]    Referring now to  FIG. 5 , the energy source within the energy delivery region  20  may comprise a fiberoptic waveguide or fiber bundle  220  carried on the rotating and translating shaft  202 . The optical waveguide  220  transmits laser or other coherent optical energy in a beam  222  which may be scanned or rastered over the urethral wall and prostatic tissue by rotating and/or translating the carrier tube  202 . 
         [0036]    As shown in  FIG. 6 , laser energy from an optical waveguide or fiber bundle  230  may be directed axially against a mirror  232 , where the waveguide and mirror are both carried on the rotating and axially translating carrier tube  202 . Again, by rotating and/or translating the carrier tube  202 , the emanating beam  234  can be scanned or rastered over the urethral wall. 
         [0037]    Referring now to  FIG. 7 , in yet another embodiment, the rotating and axially translating tube  202  may carry an electrode  240  which projects laterally from the tube. The electrode  240  will be adapted for connection to a radiofrequency energy source so that, when the electrode contacts the urethral wall and prostatic tissue, radiofrequency energy can be delivered, either in a monopolar or bipolar mode. The radiofrequency energy can thus ablate the tissue over selected volumes and regions of the prostatic tissue. Optionally, by changing the nature of the radiofrequency energy, the electrode  240  could also be used to cauterize the tissue after it has been treated. 
         [0038]    While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.