Patent Application
20070185478
The invention entails devices for selectively ablating unwanted body tissues, such as excess tissue in the male prostate gland without damaging adjoining tissues.
Benign prostatic hyperplasia, or BPH, commonly referred to as an enlarged prostate, affects more than 50% of men over age 55 and is a worldwide problem. Approximately 200,000 surgeries to treat this condition are presently performed each year in the United States at a cost estimated at $1.6 billion annually. While pharmaceuticals, such as terazosin, may limit prostate growth for a period of time, eventually a surgical solution may be required.
The long-standing surgical procedure for treating BPH is transurethral resection of the prostate or TURP, in which an electrosurgical loop heated by radiofrequency, RF, energy is moved to and from within the prostate to resect, or cut out, troughs of prostate tissue. While a TURP produces satisfactory voiding of urine, it requires general anesthesia and an hour or more of costly operating room time and entails up to 15% impotence, 5 to 10% permanent incontinence, and bleeding requiring a transfusion in up to 10% of the patients. In addition, most TURP patients suffer from retrograde ejaculation, and up to 30% or more of TURP patients experience an infection or other adverse effect.
Recently, high-powered RF roller ball devices have been introduced, which have somewhat reduced the bleeding and other adverse effects of a TURP. However, the use of RF roller ball devices requires general anesthesia and an hour or more of costly operating room time. Holmium lasers can be used for resection of the prostate, producing urine flow results equal to a TURP, while eliminating bleeding and most of the other adverse effects of the above described procedures using RF energy. However, Holmium laser resection typically requires one hour or more of expensive operating room time and general anesthesia.
The interstitial, within tissue, use of microwave, laser, or RF energy to thermally coagulate a portion of the prostate, while taking less time and avoiding general anesthesia, does not significantly reduce the prostate's volume and thus produces less urine voiding relief than a TURP, high power RF roller ball, or Holmium laser resection procedure. In addition, the patients treated with interstitial coagulating devices experience dysuria and discomfort for weeks after the procedure. If the tissue immediately underlying the urethra, which constitutes the exterior surface of the lobes of the prostate, is coagulated, the urethra dies, due to loss of its blood supply, leaving an open, irritating wound. The coagulated tissue then sloughs off and is excreted in the urine over a period of 3-6 weeks.
Laser or RF energy can be used to coagulate a tumor, but coagulation occurs irregularly, as conduction of heat through tissue of differing densities and water content is not uniform. Consequently, it is necessary to closely observe the coagulation procedure to avoid damaging nearby blood vessels, nerves and other vital tissues. While a vaporization zone can be distinguished from normal tissue by ultrasound imaging, coagulated tissue cannot be differentiated from normal tissue by ultrasound imaging. As a result, expensive magnetic resonance imaging, MRI, equipment would be required to visually monitor the coagulation procedure, so that the process can be halted if the coagulation zone approaches important blood vessels, ducts, nerves or other tissues. Unhappily, the use of MRI equipment would increase the cost of an already expensive procedure.
It would be desirable to be able to remove a sufficient amount of prostate tissue to provide immediate voiding and relief of BPH symptoms, while protecting the urethra and the immediately underlying tissue from damage, in a short outpatient procedure, preferably in an outpatient treatment facility or a physician's office under local anesthesia and/or sedation.
The present invention provides for the removal of unwanted tissue in a mammalian body, without producing excessive coagulation of surrounding tissues and avoiding thermal damage to a nearby mucosal surface or an adjacent, important blood vessel, duct, nerve or other structure.
This is achieved by a catheter device adapted to deliver thermal energy from a source local to the body tissue to be ablated, adapted for connection to a thermal heat source at its proximal end, a fluid conduit for passing a fluid into ports for anchoring and filling the proximal cuff of the thermal energy device, a separate conduit for placement of necessary connective lines to the thermal energy element and monitoring device, and a separate conduit for the drainage of bladder fluids during treatment.
The fluid can be passed through the ports by positive pressure, and can be withdrawn by vacuum, i.e., negative pressure. The distal end of the flexible energy conduit is adapted to emit energy to a predetermined tissue site so as to ablate the tissue.
In one embodiment of the present invention, energy, such as thermal energy, is transmitted through a coil element comprised of NiCr60 alloy material, whose proximal radial end is coiled about the catheter shaft, encased within a silicone or comparable tube forming an enclosed cuff about the catheter shaft. Encasing the thermal coil in a tube provides a significant holding vessel for liquid to be heated and utilized as a thermal heat transfer media to the prostate wall. A second tube, cuff, is attached directly over the coil tube and is utilized in the placement of a temperature sensing device within the boundary layer between the two tube materials, allowing measurement and subsequent control of the thermal heat energy at the point of contact with the prostate gland via a control device exterior of the subject.
In use, the present invention is inserted into tissue and oriented to produce thermal energy in a desired pattern, away from a region or tissue to be preserved, such as the mucosa or endothelial surface of an organ or an important blood vessel, duct, nerve or other structure, to prevent thermal damage thereto. The device can be orientated in a lineal direction while delivering thermal energy, or advanced and/or withdrawn while delivering thermal energy, or both. Such a device, for example, could be used to ablate a portion of the lobes of the prostate, without damaging the sensitive urethra, or its immediately underlying, supportive tissue, or without damaging surrounding normal tissue or a nearby major blood vessel, duct, nerve or other structure.
Other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment, and the accompanying drawings, wherein corresponding reference characters indicate corresponding members in which:
While this invention is susceptible of embodiment in many different forms, specific embodiments are shown in the drawings and are described herein in detail, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments illustrated.
Referring again to
Thermal welding or a comparable attachment technique such as adhesive bonding, at one or more points on the outer surface of shaft 40 around heating element 1, attaches dual-layered balloon 52 to the outer surface of shaft 40 near proximal end, preferably. Dual-layered balloon 52 is wrapped around shaft 40. The construction and operation of dual-layered balloon 52 is described in more detail below.
In this embodiment dual-layered balloon 52, wherein the dual-layered balloon 52 is constructed of one balloon around the outer surface of the catheter shaft 40 and a balloon around the outer surface of the balloon around the outer surface of the catheter shaft forming dual-layered balloon 52, attached to catheter shaft 40 by thermal welding or a comparable attachment technique such as adhesive bonding.
An apparatus aspect of the present invention is a medical catheter device for delivering localized energy to a tissue in a patient's body in an amount sufficient to ablate or vaporize the tissue. In use, the catheter device is suitably positioned within a patient's body by insertion through a body lumen, cavity or surgically created passageway, and advanced to a predetermined site within the body. The device of the present invention is particularly suited for the vaporization of prostate tissue and involves the use of thermal energy.
Numerous variations and modifications of the embodiments described above may be effected without departing from the spirit and scope of the novel features of the invention. No limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. The above description is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.
