Abstract:
An electrode for use in an electrosurgical procedure for treating entropion by excising a wedge-shaped portion of the tarsus at the underside of a patient&#39;s eyelid. In a preferred embodiment, the electrode is uniquely configured to form a diamond-shaped support terminating in an active wire, generally V-shaped, whose width controls the width of the excised wedge, and the length of whose arms controls the thickness of the excised wedge. The active wire is supported by structure that is completely electrically-insulated to ensure excision only of the desired tissue while avoiding damage to surrounding tissue. The tissue incising is effected with the bare active wire at a depth stopped by a shoulder between the bare wire arms and the adjacent portions of the electrode support.

Description:
This invention relates to an electrosurgical instrument for wedge resection, and in particular, an electrosurgical electrode for use in treating entropion. 
     BACKGROUND OF THE INVENTION 
     Entropion is an inward rotation of the eyelid margin resulting in contact between the eyelashes and the cornea, which can cause inflammation and other disorders. A known procedure for treating this condition is to resect a tissue wedge from the underside of the upper eyelid using a traditional scalpel. Closing of the resultant incision tends to rotate the eyelid margin outwardly which sufficiently alters the shape of the eyelid margin as to effectively eliminate the problem. 
     The procedure is costly and difficult to control, especially the width and thickness of tissue removal, which ideally should be limited to the tarsal width and thickness, the tarsal being the dense connective tissue forming the support of the eyelid. 
     SUMMARY OF THE INVENTION 
     An object of the invention is an improved wedge resection surgical procedure using an electrosurgical instrument. 
     We have invented a novel electrode for use in an electrosurgical wedge resection procedure. This electrosurgical procedure using our novel electrode enables physicians to offer to patients a treatment that properly removes the correct amount of tarsal tissue, is easily learned and thus performed at a significantly reduced price, and with less tissue damage and bleeding compared to procedures done with a knife or blade. 
     The electrosurgical procedure using our novel electrode is based on performing essentially the same kind of wedge resection as was used heretofore but, in accordance with a feature of our invention, the structure of our novel electrosurgical electrode used to make the excision prevents the excision depth and width from exceeding a safe value. 
     In accordance with another feature of our invention, the electrode of the invention is uniquely configured to form an active thin wire, generally V-shaped, whose width controls the width of a V-shaped tissue groove, and the length of whose arms controls the thickness of the V-shaped tissue groove. The active wire is supported by structure that is completely electrically-insulated to ensure excision only of the desired tissue while avoiding damage to surrounding tissue, and to allow the physician to use these inactive insulated parts to help position and guide the active wire portion, which is the only part capable of incising tissue, and also serves as a stop during the surgical procedure. The electrosurgical procedure has the important advantage of being able to cut the tissue with minimum surgeon pressure while at the same time coagulating the cut tissue causing minimum bleeding. It is preferred that the electrosurgical currents used be above 2 MHz, and preferably above 3 MHz. At these high frequencies, commonly referred to as radiosurgery, cutting is accomplished by volatilizing intracellular fluids at the point of the transmitting electrode contact which is primarily responsible for only small lateral heat spread and thus less damage to neighboring cell layers. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described the preferred embodiments of the invention, like reference numerals or letters signifying the same or similar components. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a plan view of one form of electrosurgical instrument in accordance with the invention, shown connected to electrosurgical apparatus; 
     FIG. 2 is a partial plan view of the electrosurgical instrument of FIG. 1 showing interior structure, 
     FIG. 3 is a schematic view illustrating the wedge resection procedure. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 illustrate a preferred form of the novel electrosurgical instrument  10  of the invention. It comprises an elongated conventional handpiece  12  (only the collet end is shown in phantom) of electrically-insulating material having a central electrically-conductive brass tube or conductor  14  extending throughout its length and connected at its end to a cable  16  which is connected in the conventional manner to conventional electrosurgical apparatus  18 . As an example only, the electrosurgical apparatus can be any radiosurgical instrument available from Elhman International, Inc. of Hewlett, N.Y. The Elhman equipment is preferred due to its high operating frequency, typically above 3 MHz, preferably from about 3.5-4 MHz. This particular apparatus provides electrosurgical currents at approximately 3.8 MHz. 
     At the opposite end of the handpiece  12  is mounted an electrosurgical electrode  20  which comprises the electrically-conductive straight axial brass rod  14  running lengthwise through it and mounted at its end nearest the handpiece  12  in the handpiece collet and thus electrically connected to the cable  16 . The distal end of the electrode comprises an electrically-conductive, generally partial diamond-shaped support  24  comprising two stiff support arms  26 ,  28 , such as metal bent tubes, for example of stainless steel, supporting a very fine metal wire, for example, of tungsten,  30 . The metal wire  30  forms a closed V having a peak  32  at the distal end and its free ends encased in the support arms  26 ,  28  extend together with the latter into the interior of the brass tube  14  to which they are solidly anchored in a good electrically conductive manner. Also connected to the electrosurgical apparatus  18  is the usual indifferent plate (not shown) which during use is in contact with a patient&#39;s body. When the electrosurgical apparatus  18  is energized, high frequency electrosurgical currents are generated which are coupled by way of the cable  16 , electrically-conductive tube  14 , and electrically-conductive tubes  26 ,  28  to the active, bare V-shaped bare wire  30 . The physician, in the usual way, holds the handpiece  12  while applying the active working end  30  of the electrode to the desired area of the patient to be treated. 
     In accordance with a feature of the invention, the active electrode portion  30  comprises a very fine, thin wire, for example, 0.004 inches in diameter of tungsten. FIG. 3 schematically shows a patient&#39;s eye with upper eyelid  48  retracted  50  upward exposing the tarsus on the lid underside. The wedge  52  excised has a triangular or V shape determined by the V-wire  30 . The V-wire  30  when activated penetrates into the tarsal tissue to the full depth of the bare arms  30 , indicated by the reference numeral  34 . Due to the shape of the V, the width of the tarsal wedge excised is determined by the width of the V, indicated by the reference numeral  36 . When activated, the active wire  30  cuts cleanly and easily with little pressure required through the tissue. 
     As will be observed, the portion of the diamond extending from the bare V  30 , which includes the metal tubes  26 ,  28  is covered with a thin layer  38  of an electrically-insulating material, and the adjacent portion of the brass tube is also covered with a layer  40  of electrically-insulating material. The thinner active wire arms  30  form, where each meets the wider electrically-insulated support arms  26 ,  28 , a shoulder  42  which acts as a stop when the active wire  32  is inserted into tissue during the procedure and thus controls the depth of the incision. 
     Electrically-insulated electrode sections which cannot contribute electrosurgical currents cannot cut tissue. With a size of the tungsten wire of, for example, 0.004 inches, and a typical diameter of the insulated support arms  26  of about 0.032 inches, a shoulder  42  is formed having a radius of about 0.016 inches, which is sufficient to prevent tissue penetration exceeding the axial length of the wire arms  30 . That length is preferably set at about 1.0 mm or somewhat larger so that the tissue wedge thickness excised will have a slightly smaller value, say 0.8 mm. For this embodiment, the width is preferably set at about 3-4 mm. The area designated  44  inside of the diamond loop formed by the active wire portions  30  and the arms  26 ,  28  is deliberately left empty. When the active wire end  30  of the electrode is inserted into the tissue up to the stops  42 , the cutting begins by pulling the electrode along the skin. The tissue wedge as it becomes excised passes upward through the clear loop area  44  and then is typically grasped with forceps and lifted clear so the surgeon can clearly see without any obstacles the cutting site from both sides and the manner in which the cutting is occurring to ensure a uniform excision. 
     The metal support arms  26 ,  28  function to support the fine tungsten wire in its V-shape. 
     In accordance with a further feature of the invention, the arms  26 ,  28  of the diamond support as well as the remaining part of the electrode shaft  20  up until it joins the bare end  14  is covered with the coatings  38 ,  40  of the electrically-insulating material. The coating  40  for the straight shaft part of the electrode may be one of many suitable electrically-insulating rubber or plastic materials. The coating  38  on the diamond support  24  comprises a thinner coating of an electrically-insulating material, which may be one of many suitable thin electrically-insulating plastics, baked Teflon being one example. Thus, the entire length of the electrode  20  from the bare active wire end  30  to the bare end  14  which is mounted in the handpiece  12  is electrically insulated from the patient. The handpiece  12 , too, is completely electrically-insulated. 
     The V-shape of the active wire end  30  is critical to achieve the desired object, which is to allow the physician to apply the electrode portion  30  to the tarsal tissue, activate the apparatus, and with relative ease penetrate the region with the bare wire  30  up to the dual stops  42 , and then move the instrument in the required path to make the desired wedge incision without fear of exceeding a safe depth of penetration, which preferably is up to about 90% of the tarsus thickness. The insulating coatings  38  and  40  are essential to prevent accidental burning or other tissue damage by the sides of the electrode as the instrument is manipulated over the skin of the patient. 
     As mentioned, preferably the transverse width  36  of the longitudinal active wire portion  30  is about 4 mm to obtain a 2-3 mm wide wedge. If desired, the width of the wire portions  30  can be increased to about 5 mm for a wider wedge, or reduced to about 1.5 mm for a narrower wedge. The slab thickness is determined by the axial length of the V-arms  30 . Preferably, that length is about 1.0 mm but can vary from about 0.8-3.5 mm. Preferably the angle subtended by the V-arms, indicated by reference numeral  46  is about 60°, but can vary between about 50-70° The configuration of the active end lends itself to the manufacture of a family of electrodes capable of providing wedges of various thicknesses and widths. For example, the same configuration as illustrated in FIG. 1 but with active wire portions  30  of different widths, say from 1-3 mm, will provide a first family of electrodes capable of providing excised grafts of about the same thickness but with different widths. Similarly, a second family can be provided with different axial lengths  34  of about 0.6-3 mm. 
     With the Ellman equipment, the fully rectified or cut/coag current is used at a power setting of about 3-4 with the active bare wire electrode  30 . There is very little trauma and the sore area felt by the patient at the eyelid site is easily handled by analgesia and anti-inflammatory and antibiotic drugs. 
     It will also be understood that the electrode of the invention is not limited to its use for a wedge resection procedure. To those skilled in this art, there will certainly be other uses for this novel electrode that provides a V-shaped active wire tip, with adjacent electrode sections coated with insulating material for accurately guiding and controlling the position of the active tip during a tissue incising electrosurgical procedure. 
     While the invention has been described in connection with preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modifications.