Abstract:
An electrocautery instrument is disclosed comprising: a handle having a handle axis; a first electrode assembly, the first electrode assembly having a first handle electrode section retained in the handle, a first oblique electrode section extending from the handle, and a first ablation electrode section disposed at an offset distance from the handle axis; and a second electrode assembly, the second electrode assembly having a second handle electrode section retained in the handle, a second oblique electrode section extending from the handle, and a second ablation electrode section disposed at the offset distance from the handle axis, the second electrode assembly being generally congruent to the first electrode assembly, the handle being configured to retain the first ablation electrode section in generally parallel relationship to the second ablation electrode section.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to surgical instruments and, more particularly, to a bipolar radio frequency ablation device for use in the removal of malignant organ tumors. 
       BACKGROUND OF THE INVENTION 
       [0002]    A common treatment for malignant tumors in human organs, such as nodules on the thyroid or renal masses on the kidney, is surgical removal of most of the respective organ tissue. For example, a thyroidectomy may be performed to deal with malignant thyroid tumors, a procedure which unfortunately results in removal of most of the thyroid tissue. Moreover, undergoing thyroid surgery often poses risks, such as nerve damage or damage to parathyroid glands, and may require that the patient take thyroid hormone supplements following surgery. Alternatives to thyroidectomy are known in the art, including radio frequency (RF) ablation techniques in which the temperature of the target tissue may be raised to a temperature of 50° C. or higher. 
         [0003]    For example, Holmer et al. have evaluated ablation methods, as reported in “Bipolar Radiofrequency Ablation for Nodular Thyroid Disease—ex Vivo and in Vivo Evaluation of a Dose-Response Relationship,”  J. Surg. Res.  2009 Oct. 29. A study in percutaneous RF ablation for benign thyroid nodules was also described by Kim et al. in “Radiofrequency Ablation of Benign Cold Thyroid Nodules: Initial Clinical Experience,”  Thyroid,  2006 April, 16(4):361-7. Kim et al. reported that the ablation electrode used was internally cooled, and that a majority of the patients required conscious sedation when undergoing the ablation procedure. 
         [0004]    While there are known in the art RF devices suitable for use in the ablation of liver tumors, for example, most such devices require an extended period of use of from five to ten minutes per session. This length of time makes it impractical to use a conventional RF device on thyroid nodules, in particular, as the thyroid will move with the swallowing motions of the patient. What is needed is an electrocautery or percutaneous ablation instrument that will allow for relatively quick excision of a malignant tissue or tumor. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    In one aspect of the present invention, an electrocautery instrument comprises: a handle having a handle axis; a first electrode assembly, the first electrode assembly having a first handle electrode section retained in the handle, a first oblique electrode section extending from the handle, and a first ablation electrode section disposed at an offset distance from the handle axis; and a second electrode assembly, the second electrode assembly having a second handle electrode section retained in the handle, a second oblique electrode section extending from the handle, and a second ablation electrode section disposed at the offset distance from the handle axis, the second electrode assembly being generally congruent to the first electrode assembly, the handle being configured to retain the first ablation electrode section in generally parallel relationship to the second ablation electrode section. 
         [0006]    In another aspect of the present invention, an electrocautery system comprises: a handle having a handle axis; a first electrode assembly partially retained in the handle, the first electrode assembly including a first active electrode distal from the handle; a second electrode assembly partially retained in the handle, the second electrode assembly including a second active electrode distal from the handle, the first active electrode retained in generally parallel relationship with the second active electrode so as to define a bipolar ablation zone therebetween, the bipolar ablation zone being in an offset and substantially parallel alignment with the handle axis; and an RF power supply electrically connected to the first electrode assembly and to the second electrode assembly, the RF power supply functioning to produce a predefined level of ablative RF power in the bipolar ablation zone. 
         [0007]    In still another aspect of the present invention, a method for ablating a tissue in a patient comprises the steps of: obtaining an instrument having both a first electrode assembly and a second electrode assembly retained in a handle, the handle retaining the first electrode section in a generally parallel relationship with the second electrode section so as to define a substantially linear bipolar ablation zone between a portion of the first electrode assembly and a portion of the second electrode assembly, the bipolar ablation zone being in an offset and substantially parallel alignment with an axis of the handle; inserting the bipolar ablation zone into a patient proximate a region containing the tissue; determining that a portion of the tissue has been positioned within the bipolar ablation zone; powering the first electrode assembly and the second electrode assembly for a predetermined time period so as to produce a predefined level of ablative RF power in the bipolar ablation zone; and removing the bipolar ablation zone from the patient. 
         [0008]    The additional features and advantage of the disclosed invention is set forth in the detailed description which follows, and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described, together with the claims and appended drawings. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0009]      FIG. 1  is an isometric illustration of an electrocautery instrument comprising a handle and a pair of electrode assemblies, in accordance with an aspect of the present invention; 
           [0010]      FIG. 2  is a partial-cutaway of the electrocautery instrument of  FIG. 1  showing blade contacts, handle electronic sections, and an electronic support insulator secured in the handle; 
           [0011]      FIG. 3  is an enlarged view of an ablation electrode section in the electrocautery instrument of  FIG. 1 ; 
           [0012]      FIG. 4  is a flow diagram illustrating operation of the electrocautery instrument of  FIG. 1 ; 
           [0013]      FIG. 5  is diagrammatical illustration of an ablating system utilizing the electrocautery instrument of  FIG. 1 ; 
           [0014]      FIG. 6  is a side view diagram of an exemplary embodiment of an electrocautery instrument, in accordance with the prior art; and 
           [0015]      FIG. 7  is a top view diagrammatical illustration of the electrocautery instrument of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0017]    The present invention comprises a bipolar radio frequency (RF) ablation or electrocautery instrument designed for percutaneous ablation of tissue in a human cavity, such as thyroid nodules or renal masses. The instrument may be inserted through a patient&#39;s skin to thyroid nodules or to renal cell carcinomas under ultrasound guidance. Activation of the instrument serves to quickly destroy the malignant tissue. The bipolar configuration provides for the ability to localize the region of ablation and to thus minimize peripheral damage to surrounding, healthy tissue. 
         [0018]    There is shown in  FIG. 1  an exemplary embodiment of an electrocautery instrument  10  comprising a handle  12  retaining a first electrode assembly  22  and a second electrode assembly  24 . The handle  12  may be fabricated from a nonconductive material, such as a plastic or dielectric. The first electrode assembly  22  and the second electrode assembly  24  are electrically connected to a first blade contact  14  and a second blade contact  16 , respectively. 
         [0019]    A blade insulation spacer  18  may be disposed between the first electrode assembly  22  and the second electrode assembly  24  so as to electrically isolate the first electrode assembly  22  from the second electrode assembly  24 . The first electrode assembly  22  and the second electrode assembly  24  may thus be powered by applying RF power to the first blade contact  14  and the second blade contact  16 . 
         [0020]    As shown in the diagram, the portions of the first electrode assembly  22  and the second electrode assembly  24  distal from the handle  12  are in an offset configuration. These distal electrode assembly portions lie along an ablator axis  34  that is offset from a handle axis  32  that lies along a centerline of the handle  12 . As can be appreciated by one skilled in the art, the offset configuration shown is particularly advantageous providing a clear view of the skin puncture site before insertion of the distal electrode assembly portions into the patient. 
         [0021]    As shown in  FIG. 2 , the first electrode assembly  22  comprises a first handle electrode section  42 , a first oblique electrode section  44 , and a first ablation electrode section  46 . The first handle electrode section  42  may be electrically connected to the first blade contact  14  at an electrical attachment  48 , such as by brazing or welding. The second electrode assembly  24  is similar in configuration to the first electrode assembly  22 . Accordingly, the second electrode assembly comprises a second handle electrode section  52 , a second oblique electrode section  54 , and a second ablation electrode section  56 . 
         [0022]    The handle  12  is configured to retain the first blade contact  14  and the second blade contact  16  at the rear of the handle  12 . An electrode support insulator  26  may be provided at the front of the handle  12  to retain the first handle electrode section  42  and the second handle electrode section  52  in a spaced apart, substantially parallel relationship. 
         [0023]    As best shown in  FIG. 3 , the first ablation electrode section  46  may be partially covered with the insulating sleeve  36  to form an insulated ablation electrode  62  for part of the length of the first ablation electrode section  46 , and a first active electrode  64  without the insulating sleeve  36  for the remaining length of the first ablation electrode section  46 . Similarly, the second ablation electrode section  56  may be partially covered with the insulating sleeve  36  to form a second active electrode  66 , where a bipolar ablation zone  68  may be defined as the region between the first active electrode  64  and the second active electrode  66 . This configuration serves to restrict any electrical discharge between the first electrode assembly  22  and the second electrode assembly  24  to the bipolar ablation zone  68 . 
         [0024]    It can be appreciated that the exposed lengths of the active electrodes  64 ,  66  determine the size of the resulting ablated lesion. The exposed lengths of the active electrodes  64 ,  66  are thus a function of the size of the target tumor. In an exemplary embodiment, the spacing between the first active electrode  64  and the second active electrode  66  is specified so as to be able to enclose a thyroid nodule or a renal carcinoma between the first active electrode  64  and the second active electrode  66  for cauterization by the electrocautery instrument  10 . 
         [0025]    Operation of the electrocautery instrument  10  may be described with reference to a flow diagram  70 , shown in  FIG. 4 , in which the electrocautery instrument  10  with the offset bipolar ablation zone  68  is obtained, at step  72 . With additional reference to  FIG. 5 , the first ablation electrode section  46  and the second ablation electrode section  56  are inserted into a patient  92 , at step  74 . The bipolar ablation zone  68  may be guided to a target tissue or to a region of interest, such as a thyroid or a kidney, using feedback from an ultrasound imaging unit  98 , at step  76 . 
         [0026]    It can be appreciated that, as the first ablation electrode section  46  and the second ablation electrode section  56  are formed from metal, the location of the first ablation electrode section  46  and the second ablation electrode section  56  inside the patient can be established by means of ultrasound imaging. Power may be applied to the electrocautery instrument  10 , at step  78 , using an RF power source  94  and control unit  96 . In an exemplary embodiment, the RF power source  94  may output between about ten watts and twenty watts of RF power at an operating frequency of about 800 MHz to about 6.0 GHz. 
         [0027]    The RF power source  94  may provide ablative energy to the bipolar ablation zone  68  for a predetermined period of time to complete the electrocautery or percutaneous ablation procedure, at step  80 . In an exemplary embodiment, the predetermined period of time may comprise a duration of from about ten seconds to about thirty seconds. Because the electrocautery procedure can be completed within the upper time period of thirty seconds, it may not be necessary to have the patient placed under general anesthesia. The control unit  96  may be used to power down the RF power source  94  to terminate the ablation process. The first ablation electrode section  46  and the second ablation electrode section  56  may then be removed from the patient  92 , at step  82 . 
         [0028]    In an exemplary embodiment, an electrocautery instrument  100  may be fabricated as a device having an overall length of approximately 243 mm, as shown in  FIGS. 6 and 7 . The electrocautery instrument  100  may comprise a handle  110  approximately 126 mm in length and about 12.7 mm in diameter. A first blade contact  104  and a second blade contact  106  are configured to interface with standard RF power supplies and, accordingly, may each have a width of about 7.0 mm, protrude approximately 14 mm from the handle  110 , and have outer surfaces spaced at a distance of about 4 mm. 
         [0029]    The electrocautery instrument may comprise a first active electrode  112  and a second active electrode  114 , each about 10 mm in length. The first active electrode  112  may be spaced from the second active electrode  114  by a distance of about 2.8 mm, although an alternative spacing of from about 2.2 mm to about 3.2 mm would lie within the scope of the present invention. This range of dimensions enables an optimal bipolar cautery to provide for a relatively quick ablation procedure. In addition, damage to surrounding tissue may be mitigated or eliminated by using the relatively quick procedure. 
         [0030]    The diameters of the first active electrode  112  and the second active electrode  114  may be about 0.6 mm in diameter. The configuration shown provides for a bipolar ablation zone  116  of about 10 mm by about 2.2 mm. An ablator axis  122  may be offset from a handle axis  124  by a distance of about 20 mm as shown, although an alternative offset distance of from about 10 mm to about 30 mm would also lie within the scope of the present invention. An oblique electrode section  126  may form an angle of approximately 45° with the handle axis. 
         [0031]    It is to be understood that the description herein is exemplary of the invention only and is intended to provide an overview for the understanding of the nature and character of the invention as it is defined by the claims. The accompanying drawings are included to provide a further understanding of various features and embodiments of the method and apparatus of the invention which, together with their description serve to explain the principles and operation of the invention. Thus, while the invention has been described with reference to particular embodiments, it will be understood that the present invention is by no means limited to the particular constructions and methods herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.