Abstract:
A disposable electrode paddle assembly is provided and includes a shaft having a proximal end and a distal end; a handle assembly supported at the proximal end of the shaft; a spoon supported at the distal end of the shaft; an electrical conductor extending from the handle assembly and establishing an electrical connection at the spoon; and an electrode assembly selectively, electrically connectable to the electrical connection provided at the spoon; wherein the electrode assembly includes a layer of silver/silver-chloride (Ag/AgCl) having one of an increasing and decreasing density extending in a radially outward direction.

Description:
BACKGROUND 
       [0001]    1. Field of Invention 
         [0002]    The present disclosure relates to electrodes and, inure particularly, to disposable internal defibrillation electrode/lead paddle assemblies configured for external transthorasic defibrillation, pacing, and electrocardiogram acquisition. 
         [0003]    2. Background 
         [0004]    Electrodes, which are typically used in medical applications, generally include a conductor and a connector. The connector is attached at one end to the conductor and includes a plug at the other end to be plugged into a defibrillator or other device. The conductor is often covered or coated in a conductive gel, which enhances its ability to adhere to a patient&#39;s skin. 
         [0005]    During open-heart surgery, a pair of internal defibrillation paddles is used to restart the patient&#39;s heart. In use, each paddle is held in direct contact against the myocardium (heart muscle). An electric discharge is passed from one electrode through the patient&#39;s heart to a second electrode in an effort to restart the patient&#39;s heart. 
         [0006]    However, prior to use, electrodes must be sterilized to eliminate patient infection. Modern sterilization methods use heat or chemical agents, such as ethylene oxide. The methods and materials used degrade the electrodes, thus limiting their useful life. Most manufacturers specify a maximum service life for electrodes. However, there is no convenient mechanism for users to measure and track the number of sterilization cycles an electrode experiences. Therefore, there is no easy way to determine if the service life of the electrodes has been exceeded. 
         [0007]    Therefore, a need exists for electrodes that may used on a patient once and then disposed of. 
       SUMMARY 
       [0008]    According to an aspect of the present disclosure, a disposable electrode paddle assembly is provided and includes a shaft having a proximal end and a distal end; a handle assembly supported at the proximal end of the shaft; a spoon supported at the distal end of the shaft; an electrical conductor extending from the handle assembly and establishing an electrical connection at the spoon; and an electrode assembly selectively, electrically connectable to the electrical connection provided at the spoon. The electrode assembly includes a layer of silver/silver-chloride (Ag/AgCl) having one of an increasing and decreasing density extending in a radially outward direction. 
         [0009]    The layer of silver/silver-chloride (Ag/AgCl) may include a first area having a first density and a second area having a second density, greater than the first density, and may be disposed radially inward or radially outward of the first area. 
         [0010]    The second area may be substantially centrally located within an outer diameter of the electrode assembly. The first area may be substantially circular. The second area may be spaced a radial distance inward from an outer edge of the electrode. 
         [0011]    The silver/silver-chloride (Ag/AgCl) layer may be composed of about 62% silver (Ag) and about 38% chloride (Cl). The silver/silver-chloride (Ag/AgCl) layer may have a thickness of less than 10 μm. 
         [0012]    The first area may have a higher impedance than the second area. The second area may have a higher impedance than the first area. 
         [0013]    An outer edge of the first area may include an annular array of spikes extending at least partially therearound; and an outer edge of the second area may include an annular array of spikes extending at least partially therearound. 
         [0014]    The electrode assembly may further include at least one lead wire in electrical communication with the layer of silver/silver-chloride (Ag/AgCl). The at least one lead wire may be in operative communication with the electrical connection at the spoon. 
         [0015]    According to another aspect of the present disclosure, a disposable electrode paddle assembly is provided and includes a shaft having a proximal end and a distal end; a handle assembly supported at the proximal end of the shaft; a spoon supported at the distal end of the shaft; an electrical conductor extending from the handle assembly and establishing an electrical connection at the spoon; and an electrode assembly selectively, electrically connectable to the electrical connection provided at the spoon. The electrode assembly includes a first substrate constructed from an electrically insulative material; a second substrate constructed, at least partially, from a conductive material; a third substrate being a carbon/vinyl film; a fourth substrate being a conductive hydrogel; and a single layer of silver/silver-chloride (Ag/AgCl) interposed between adjacent substrates. The layer of silver/silver-chloride (Ag/AgCl) has one of an increasing and decreasing density extending in a radially outward direction. 
         [0016]    The first substrate may be constructed from an X-ray transparent material. 
         [0017]    The layer of silver/silver-chloride (Ag/AgCl) may be disposed between the second substrate and the third substrate. The layer of silver/silver-chloride (Ag/AgCl) may be disposed between the third substrate and the fourth substrate. 
         [0018]    The third substrate may be constructed from a flexible sheet of graphite filled polyvinyl chloride film having a thickness from about 2 mils to about 4 mils. 
         [0019]    The silver/silver-chloride (Ag/AgCl) layer may be composed of 62% silver (Ag) and 38% chloride (Cl). The silver/silver-chloride (Ag/AgCl) layer may have a thickness of less than 10 μm. 
         [0020]    The layer of silver/silver-chloride (Ag/AgCl) may include a first area having a first density and a second area having a second density, greater than the first density, and may be disposed one of radially inward and radially outward of the first area. 
         [0021]    The second area may be substantially centrally located within an outer diameter of the electrode assembly. The first area may be substantially circular. The second area may be spaced a radial distance inward from an outer edge of the electrode. 
         [0022]    The first area may have a higher impedance than the second area. The second area may have a higher impedance than the first area. 
         [0023]    An outer edge of the first area may include an annular array of spikes extending at least partially therearound; and an outer edge of the second area may include an annular array of spikes extending at least partially therearound. 
         [0024]    The electrode assembly may further include at least one lead wire in electrical communication with the layer of silver/silver-chloride (Ag/AgCl). 
         [0025]    The at least one lead wire may be in operative communication with the electrical connection at the spoon. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Various embodiments of the disposable internal defibrillation electrode paddle assembly are described herein with reference to the drawings wherein: 
           [0027]      FIG. 1  is a perspective view of an internal defibrillation electrode paddle assembly, according to an embodiment of the present disclosure; 
           [0028]      FIG. 2  is a perspective view, with layers separated, of an electrode, according to an embodiment of the present disclosure, for use with the internal defibrillation electrode paddle assembly; 
           [0029]      FIG. 3  is a perspective view, with layers separated, of an electrode, according to another embodiment of the present disclosure, for use with the internal defibrillation electrode paddle assembly; 
           [0030]      FIG. 4  is a perspective view, with layers separated, of an electrode, according to yet another embodiment of the present disclosure, for use with the internal defibrillation electrode paddle assembly; and 
           [0031]      FIG. 5  is a perspective view, with layers separated, of an electrode, according to still another embodiment of the present disclosure, for use with the internal defibrillation electrode paddle assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Embodiments of the presently disclosed disposable internal defibrillation electrode paddle assembly will now be described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical elements. 
         [0033]    As illustrated in  FIG. 1 , a pair of defibrillator electrode paddle assemblies, according to an embodiment of the present disclosure, is illustrated with each electrode paddle assembly being generally designated as  10 . Each defibrillation electrode paddle assembly  10  includes a handle  12 , a shaft  14  extending from the handle  12 , and a spoon  16  supported on an end of the shaft  14 . Each defibrillation electrode paddle assembly  10  includes a cable  20  extending from handle  12  and including a plug  22  for connection with a defibrillator monitor (not shown). Each cable  20  extends through shaft  14  to spoon  16  and provides an electrical contact region for spoon  16 . Each spoon  16  is configured to selectively support/connect an electrode assembly  100  thereto and electrically contact the end of cable  20 . 
         [0034]    Electrode  100 , and alternate embodiments thereof, will be further described with reference to  FIGS. 2-5 . It is noted that the electrodes described in  FIGS. 2 ,  3 , and  6  are constructed to have a higher impedance near the edges thereof as compared to a center thereof. 
         [0035]    Referring to  FIG. 2 , a first embodiment of the electrode assembly is generally designated as  100 . Electrode assembly  100  includes a backing substrate or cover  110  defining a first or front side  110   a  facing a subject (not shown) and a second or back side  110   b , opposite first side  110   a  and facing away from the subject. 
         [0036]    Cover  110  is fabricated from an electrically insulative and X-ray transparent material having sufficient strength and rigidity to support an electrode. Cover  110  may be clear in order to enable a user to see through the cover  110 . Cover  110  is circular or disc-shaped although other shapes such as square, rectangular, and triangular are contemplated. Cover  110  may have any regular or irregular shape according to a desired use. One skilled in the art may contemplate fabricating cover  110  from a plurality of suitable materials in accordance with desired applications. In one embodiment, the backing may be a low cost material so that disposal after single patient use is not cost prohibitive. In one embodiment, cover  110  is a nonconductive foam, such as polyethylene foam having a thickness of about 1/16 of an inch. 
         [0037]    Electrode assembly  100  includes a conductive layer  150  defining a first or front side  150   a  facing a subject (not shown) and a second or back side  150   b , opposite first side  150   a  and facing away from the subject. Conductive layer  150  may be any conductive material such as carbon/vinyl film, conductive rubber, a metallic foil such as aluminum foil, tin foil, silver foil, and copper foil and may be dimensioned to have a first diameter that is smaller than a diameter of cover  110 . Carbon/vinyl film  150  is in contact with Ag/AgCl coating  160  and with first side  110   a  of cover  110  located radially outward of perimetrical region  164  of Ag/AgCl coating  160 . 
         [0038]    Carbon/vinyl film  150  is formed of a thin flexible sheet of graphite filled polyvinyl chloride film having a thickness of the order of about two to four mils. Carbon/vinyl film  150  is a commercial product available and purchased from Exopack™, LLC, 345 Cedar Springs Ave., Spartanburg, S.C. Carbon/vinyl film  150 , including coating  160  of Ag/AgCl ink, is inherently radiolucent. One skilled in the art may contemplate fabricating carbon/vinyl film  150  from a plurality of suitable materials in accordance with desired applications. 
         [0039]    Electrode assembly  100  includes a coating of silver/silver-chloride (Ag/AgCl) ink  160  disposed on second or back side  150   b  of carbon/vinyl film  150 . Ag/AgCl coating  160  is printed on second or back side  150   b  of carbon/vinyl film  150 . Ag/AgCl coating  160  includes a central region  162  of continuous 100% or substantially continuous coverage and a perimetrical region  164  having less than substantially continuous coverage. In one embodiment, the silver/silver-chloride ink coverage in the perimetrical region  164  may be about 50%. Silver/silver-chloride ink may be deposited in the perimetrical region  164  by conventional methods in a desired pattern which may be regular, irregular, random and combinations thereof. In one embodiment, the ink in the perimetrical region  164  may be a speckle or spray pattern. In another embodiment, the ink in the perimetrical region may be a regular pattern such as squares, triangles, stripes of similar or varying thickness. The density of the ink applied to the perimetrical region may vary throughout the region and may form a gradient. For example, the density of the ink may be higher in the portion of the perimetrical region  164  adjacent the central region  162  and lower at one or more locations further from the central region  162 . Alternatively, the density of the ink may be lower in the portion of the perimetrical region  164  adjacent the central region  162  and higher at one or more locations further from the central region  162 . The embodiment of  FIG. 2  illustrates a solid silver portion  162  surrounded by the perimetrical region  164  having a substantially uniform silver/silver chloride coverage of about 50% silver, both deposited on the unprinted conductive layer. 
         [0040]    Central region  162  of Ag/AgCl coating  160  is shown as substantially circular including an array of spikes  162   a  therearound extending radially outward, although it is understood that other shapes and cross sectional areas are contemplated depending on a desired use. The spikes may be sized and shaped for a particular purpose and may, but need not be identical. The spikes may, but need not be spaced equidistantly about the outer periphery of the central region  162 . Although the spikes are shown to originate from a V-Shape and culminate in a point, the spikes may have a variety of shapes, for example originating from a U shape and/or culminating in a rounded or blunt tip. Central region  162  of Ag/AgCl coating  160  defines a second diameter that is smaller than the first diameter of carbon/vinyl film  150 . 
         [0041]    Perimetrical region  164  of Ag/AgCl coating  160  is shown as substantially circular including an array of spikes  164   a  therearound extending radially outward, although it is understood that other shapes and cross sectional areas are contemplated depending on a desired use. The spikes may, but need not be spaced equidistantly about the outer periphery. Although the spikes are shown to originate from a V-Shape and culminate in a point, the spikes may have a variety of shapes, for example originating from a U-Shape and/or culminating in a rounded or blunt tip. The overall shape of the perimetrical region may, but need, not have the same general shape as the central region. For example, the location of the spikes in the perimetrical region may, but need not, align with the spikes extending from the central region. Perimetrical region  164  of Ag/AgCl coating  160  defines a third diameter that is smaller than the first diameter of carbon/vinyl film  150  and larger than the second diameter of central region  162 . Perimetrical region  164  is sized to define an area between the outer edge thereof and the outer edge of carbon/vinyl film  150  that is free from any coating of Ag/AgCl ink. 
         [0042]    Ag/AgCl ink is applied in a coating to second or back side  150   b  of carbon/vinyl film  150  by conventional methods such as silk screening, flexographic printing, spray coating, transfer coating, rotogravure, and off set letter press. The thickness of the Ag/AgCl coating  160  may be any desired thickness suitable for a particular purpose and sufficient to provide good electrical conductivity without substantially impairing the X-ray transparency of the electrode member. Additionally, Ag/AgCl coating  160  has a thickness which does not noticeably effect or change the flexibility of electrode assembly  100 . In one embodiment, the Ag/AgCl coating has a thickness of about ten microns. 
         [0043]    Ag/AgCl coating  160  may be composed of about 62% Ag and about 38% AgCl. In one embodiment, the Ag/AgCl coating may be composed of about 50% Ag and about 50% Cl. In yet another embodiment, the Ag/AgCl coating may be comprised of about 83% AG and about 17% Cl. Such a composition of Ag/AgCl may result in a coating of Ag/AgCl having no or insufficient structural integrity on its own and thus is conventionally applied to a backing layer in order to form any pattern. As such, Ag/AgCl coating  160  is not typically an independent layer. One skilled in the art may contemplate using any types of conductive materials in any number of different compositions to achieve desired results. For example, the conductive silver coating may be formed as a free standing film and could replace the carbon/vinyl film. 
         [0044]    Electrode assembly  100  is electrically connectable with a first end  192  of a lead wire  190  interposed between cover  110  and Ag/AgCl coating  160 . A second end  194  of lead wire  190  extends from a side of electrode assembly  100  and is configured to electrical connection to cable  20 , via a plug, a contact pad/tab or the like. 
         [0045]    Electrode assembly  100  includes a conductive hydrogel  170  defining a first or front side  170   a  facing a subject (not shown) and a second or back side  170   b , opposite first side  170   a  and facing away from the subject, wherein back side  170   b  of hydrogel  170  is in contact with first side  150   a  of conductive/vinyl film  150 . Hydrogel  170  provides an electromechanical interface between electrode assembly  100  and the subject (not shown). Hydrogel  170  may also adhesively connect electrode assembly  100  to the subject. 
         [0046]    Additionally, electrode assembly  100  may include a release liner  180  underlying hydrogel  170  to protect hydrogel  170  prior to use. 
         [0047]    Referring to  FIG. 3 , a second embodiment of an electrode assembly is generally designated as  200 . Electrode assembly  200  includes a backing substrate or cover  210  defining a first or front side  210   a  facing a subject (not shown) and a second or back side  210   b , opposite first side  210   a  and facing away from the subject. 
         [0048]    Cover  210  is fabricated from an electrically insulative substrate and may be an X-ray transparent material and may have sufficient strength and rigidity to support an electrode. Cover  210  may be clear in order to enable a user to see through the cover  210 . Cover  210  may have any regular or irregular shape suitable for a particular use. Cover  210  is circular or disc-shaped first diameter although other shapes such as square, rectangular, and triangular are contemplated. One skilled in the art may contemplate fabricating cover  210  from a plurality of suitable materials in accordance with desired applications. In one embodiment, the backing may be a low cost material so that disposal after single patient use is not cost prohibitive. In one embodiment, cover  110  is a nonconductive foam, such as polyethylene foam having a thickness of about 1/16 of an inch. 
         [0049]    Electrode assembly  200  includes a conductive layer  250  defining a first or front side  250   a  facing a subject (not shown) and a second or back side  250   b , opposite first side  250   a  and facing away from the subject. The conductive layer may be formed of any conductive material such as carbon/vinyl conductive rubber, a metallic foil such as aluminum foil, silver foil, tin foil and copper foil and may be dimensioned to have a diameter that is smaller than a diameter of cover  210 . In one embodiment a carbon/vinyl film  250  is in contact with front side  210   a  of cover  210 . 
         [0050]    Carbon/vinyl film  250  is formed of a thin flexible sheet of graphite filled polyvinyl chloride film having a thickness of the order of about two to four mils. Carbon/vinyl film  250  is a commercial product available and purchased from Exopack™, LLC, 345 Cedar Springs Ave., Spartanburg, S.C. One skilled in the art may contemplate fabricating carbon/vinyl film  250  from a plurality of suitable materials in accordance with desired applications. 
         [0051]    Electrode assembly  200  is electrically connectable with a first end  292  of a lead wire  290  interposed between cover  210  and carbon/vinyl film  250 . A second end  294  of lead wire  290  extends from a side of electrode assembly  200  and is configured to electrical connection to cable  20 , via a plug, a contact pad/tab or the like. 
         [0052]    Electrode assembly  200  includes a coating of silver/silver-chloride (Ag/AgCl) ink  260  disposed on first or front side  250   a  of carbon/vinyl film  250 . Ag/AgCl coating  260  is screen printed on front side  250   a  of carbon/vinyl film  250 . Ag/AgCl coating  260  includes a central region  262  of continuous 100% coverage, or substantially continuous, and a perimetrical region  264  having less than substantially continuous coverage. In one embodiment, the silver/silver-chloride ink coverage in the perimetrical region  264  may be about 50%. Silver/silver-chloride ink may be deposited in the perimetrical region  264  by conventional methods in a desired pattern which may be regular, irregular, random and combinations thereof. In one embodiment, the ink in the perimetrical region  264  may be a speckle or spray pattern. In another embodiment, the ink in the perimetrical region may be a regular pattern such as squares, triangles, stripes of similar or varying thickness. The density of the ink applied to the perimetrical region may vary throughout the region and may form a gradient. For example, the density of the ink may be higher in the portion of the perimetrical region  264  adjacent the central region  262  and lower at one or more locations further from the central region  262 . Alternatively, the density of the ink may be lower in the portion of the perimetrical region  264  adjacent the central region  262  and higher at one or more locations further from the central region  262 . 
         [0053]    Central region  262  of Ag/AgCl coating  260  is substantially circular and includes an array of spikes  262   a  therearound extending radially outward. Central region  262  of Ag/AgCl coating  260  defines a second diameter that is smaller than a first diameter of carbon/vinyl film  250 . 
         [0054]    Perimetrical region  264  of Ag/AgCl coating  260  is shown as substantially circular including an array of spikes  264   a  therearound extending radially outward, although it is understood that other shapes and cross sectional areas are contemplated depending on a desired use. The spikes may, but need not be spaced equidistantly about the outer periphery. Although the spikes are shown to originate from a V-shape and culminate in a point, the spikes may have a variety of shapes, for example of originating from a U-shape and/or culminating in a rounded or blunt tip. The overall shape of the perimetrical region may but need not have the same general shape as the central region. For example, the location of the spikes in the perimetrical region may, but need not, align with the spikes extending from the central region. Perimetrical region  264  of Ag/AgCl coating  260  defines a third diameter that is smaller than the first diameter of carbon/vinyl film  250  and larger than the second diameter of central region  262 . Perimetrical region  264  is sized to define an area between the outer edge thereof and the outer edge of carbon/vinyl film  250  that is free from any coating of Ag/AgCl ink. 
         [0055]    Ag/AgCl ink is applied in a coating to first or front side  250   a  of carbon/vinyl film  250  by silk screening, flexographic printing, spray coating, and transfer coating. The thickness of the Ag/AgCl coating  260  may be any desired thickness suitable for a particular purpose and sufficient to provide good electrical conductivity without substantially impairing the X-ray transparency of the electrode member. Additionally, Ag/AgCl coating  260  has a thickness which does not noticeably effect or change the flexibility of electrode assembly  200 . In one embodiment, the Ag/AgCl coating has a thickness of about ten microns. 
         [0056]    Ag/AgCl coating  260  is composed of about 62% Ag and about 38% AgCl. In one embodiment the Ag/AgCl coating may be composed of about 50% Ag and about 50% Cl. In yet another embodiment, the Ag/AgCl coating may be composed of about 83% Ag and about 17% Cl. Such a composition of Ag/AgCl results in a coating of Ag/AgCl having no or insufficient structural integrity on its own and thus is conventionally applied to a backing layer in order to form any pattern. As such, Ag/AgCl coating  260  is not typically an independent layer. Carbon/vinyl film  250 , including coating  260  of Ag/AgCl ink, is inherently radiolucent. One skilled in the art may contemplate using any types of conductive materials in any number of different compositions to achieve desired results. For example, the conductive silver coating may be formed as a free standing film and could replace the carbon/vinyl film. 
         [0057]    Electrode assembly  200  includes a conductive hydrogel  270  defining a first or front side  270   a  facing a subject (not shown) and a second or back side  270   b , opposite first side  270   a  and facing away from the subject, wherein back side  270   b  of hydrogel  270  is in 100% direct contact with front side  250   a  of conductive/vinyl film  250  located radially outward of perimetrical region  264  of Ag/AgCl coating  260 , in approximately 50% direct contact with skin side  250   a  of conductive/vinyl film  250  located in perimetrical region  264 , and in 100% direct contact with central region  262  of Ag/AgCl coating  260 . Hydrogel  270  provides an electromechanical interface between electrode assembly  200  and the subject (not shown). Hydrogel  270  may also adhesively connect electrode assembly  200  to the subject. 
         [0058]    Electrode assembly  200  may include a release liner  280  underlying hydrogel  270  to protect hydrogel  270  prior to use. 
         [0059]    Alternatively to electrode assemblies  100  and  200 , electrode assemblies may be constructed to have a higher impedance near a center thereof as compared to the edges thereof, as illustrated in  FIGS. 4 and 5 . 
         [0060]    With reference to  FIG. 4 , a third embodiment of an electrode assembly is generally designated as  300 . Electrode assembly  300  includes a backing substrate or cover  310  defining a first or front side  310   a  facing a subject (not shown) and a second or back side  310   b , opposite first side  310   a  and facing away from the subject. 
         [0061]    Cover  310  is fabricated from an electrically insulative substrate and may be an X-ray transparent material and have sufficient strength and rigidity to support an electrode. Cover  310  may be clear in order to enable a user to see through the cover  310 . Cover  310  may have any regular or irregular shape suitable for a particular purpose. Cover  310  is circular or disc-shaped, although other shapes such as square, rectangular, and triangular are contemplated. One skilled in the art may contemplate fabricating cover  310  from a plurality of suitable materials in accordance with desired applications. In one embodiment, the backing may be a low cost material so that disposal after a single use is not cost prohibitive. In one embodiment, cover  310  is a nonconductive foam such as polyethylene foam having a thickness of about 1/16 of an inch. 
         [0062]    Electrode assembly  300  includes a conductive layer  350  defining a first or front side  350   a  facing a subject (not shown) and a second or back side  350   b , opposite first side  350   a  and facing away from the subject. Conductive layer  350  may be formed of any conductive material, such as carbon/vinyl film, conductive rubber, a metallic foil such as aluminum foil, silver foil, tin foil and copper foil and may be dimensioned to have a first diameter that is smaller than a diameter of cover  310 . Carbon/vinyl film  350  is in contact with an Ag/AgCl coating  360  and with front side  310   a  of cover  310  located within an open central region  366  of Ag/AgCl coating  360 . 
         [0063]    Carbon/vinyl film  350  is formed of a thin flexible sheet of graphite filled polyvinyl chloride film having a thickness of the order of about two to four mils. Carbon/vinyl film  350  is a commercial product available and purchased from Exopack™, LLC, 345 Cedar Springs Ave., Spartanburg, S.C. Carbon/vinyl film  350 , including coating  360  of Ag/AgCl ink, is inherently radiolucent. One skilled in the art may contemplate fabricating carbon/vinyl film  350  from a plurality of suitable materials in accordance with desired applications. 
         [0064]    Electrode assembly  300  includes a coating of silver/silver-chloride (Ag/AgCl) ink  360  disposed on second or back side  350   b  of carbon/vinyl film  350 . Ag/AgCl coating  360  is deposited on second or back side  350   b  of carbon/vinyl film  350 . Ag/AgCl coating  360  includes an outer ring or region  362  of continuous 100% coverage or substantially continuous and an inner ring or region  364  having less than substantially continuous coverage. Ag/AgCl coating  360  defines an open central region  366  that is free of Ag/AgCl ink. In one embodiment, the silver/silver-chloride ink coverage in the inner ring  364  may be about 50%. Silver/silver-chloride ink may be deposited in the inner ring  364  by conventional methods in a desired pattern which may be regular, irregular, random and combinations thereof. In one embodiment, the ink in the inner ring  364  may be a speckle or spray pattern. In another embodiment, the ink in the inner ring may be a regular pattern such as squares, triangles, stripes of similar or varying thickness. The density of the ink applied to the inner ring may vary throughout the region and may form a gradient. For example, the density of the ink in the inner ring may be higher in the region adjacent the central region  366  and lower at one or more locations adjacent the outer ring  362 . Alternatively, the density of the ink may be lower in the region adjacent the central region  366  and higher at one or more locations adjacent the outer ring  362 . Outer ring  362  of Ag/AgCl coating  360  is shown as substantially circular including an array of spikes  362   a  therearound extending radially inward, although it is understood that other shapes and cross sectional areas are contemplated depending on the desired use. Outer ring  362  of Ag/AgCl coating  360  extends radially inward to a second diameter that is smaller than the first diameter of carbon/vinyl film  350 . The spikes may be sized and shaped for a particular purpose and may, but need not be identical to one another. The spikes may, but need not be spaced equidistantly about the inner periphery of the outer ring. Although the spikes are shown to originate from a V-shape and culminate in at point, the spikes may have a variety of shapes, for example, originating from a U shape and/or culminating in a rounded or blunt tip. 
         [0065]    Inner ring or region  364  of Ag/AgCl coating  360  is shown as substantially circular including an array of spikes  364   a  therearound extending radially inward, although it is understood that other shapes and cross sectional areas are contemplated depending on the desired use. Inner ring or region  364  of Ag/AgCl coating  360  extends radially inward to a third diameter that is smaller than the second inner diameter of outer ring  362  and defines the open central region  366  that is free from any coating of Ag/AgCl ink. The spikes may be sized and shaped for a particular purpose and may, but need not be identical to one another. The spikes may, but need not be spaced equidistantly about the inner periphery of the inner ring. Although the spikes are shown to originate from a V-shape and culminate in at point, the spikes may have a variety of shapes, for example, originating from a U-shape and/or culminating in a rounded or blunt tip. 
         [0066]    Ag/AgCl ink is applied in a coating to second or back side  350   b  of carbon/vinyl film  350  by conventional methods such as silk screening, flexographic printing, spray coating, transfer coating, rotogravure and off set letter press. The thickness of the Ag/AgCl coating  360  may be any desired thickness suitable for a particular purpose and sufficient to provide good electrical conductivity without substantially impairing the X-ray transparency of the electrode member. Additionally, Ag/AgCl coating  360  has a thickness which does not noticeably effect or change the flexibility of electrode assembly  300 . In one embodiment, the AG/AgCl coating has a thickness of about ten microns. 
         [0067]    Ag/AgCl coating  360  is composed of about 62% Ag and about 38% AgCl. In one embodiment, the Ag/AgCl coating may be composed of about 50% Ag and about 50% AgCl. In yet another embodiment, the Ag/AgCl coating may be composed of about 83% Ag and about 17% Cl. Such a composition of Ag/AgCl results in a coating of Ag/AgCl having no or insufficient structural integrity on its own and is conventionally applied to a backing layer in order to form any pattern. As such, Ag/AgCl coating  360  is not typically an independent layer. One skilled in the art may contemplate using any types of conductive materials in any number of different compositions to achieve desired results. For example, the conductive silver coating may be formed is a free standing film and could replace the carbon/vinyl film. 
         [0068]    Electrode assembly  300  is electrically connectable with a first end  392  of a lead wire  390  interposed between cover  310  and Ag/AgCl coating  360 . A second end  394  of lead wire  390  extends from a side of electrode assembly  300  and is configured to electrical connection to cable  20 , via a plug, a contact pad/tab or the like. 
         [0069]    Electrode assembly  300  includes a conductive hydrogel  370  defining a first or front side  370   a  facing a subject (not shown) and a second or back side  370   b , opposite first side  370   a  and facing away from the subject, wherein back side  370   b  of hydrogel  370  is in contact with front side  350   a  of conductive/vinyl film  350 . Hydrogel  370  provides an electromechanical interface between electrode assembly  300  and the subject (not shown). Hydrogel  370  also adhesively connects electrode assembly  300  to the subject. 
         [0070]    Electrode assembly  300  may include a release liner  380  underlying hydrogel  370  to protect hydrogel  370  prior to use. 
         [0071]    Referring to  FIG. 5 , a fourth embodiment of an electrode assembly is generally designated as  400 . Electrode assembly  400  includes a backing substrate or cover  410  defining a first or front side  410   a  facing a subject (not shown) and a second or back side  410   b , opposite first side  410   a  and facing away from the subject. 
         [0072]    Cover  410  is fabricated from an electrically insulative and may be an X-ray transparent material and have sufficient strength and rigidity to support an electrode. Cover  410  may be clear in order to enable a user to see through the cover  410 . Cover  410  is circular or disc-shaped defining a first diameter, although other shapes such as square, rectangular, and triangular are contemplated. Cover  410  may have any regular or irregular shape suitable for a desired purpose. One skilled in the art may contemplate fabricating cover  410  from a plurality of suitable materials in accordance with desired applications. In one embodiment, the backing may be a low cost material so that disposal after single patient use is not cost prohibitive. In one embodiment, cover  410  is non conductive foam, such as polyethylene form having a thickness of about 1/16 of an inch. 
         [0073]    Electrode assembly  400  includes a conductive layer film  450  defining a first or front side  450   a  facing a subject (not shown) and a second or back side  450   b , opposite first side  450   a  and facing away from the subject. Conductive layer may be formed of any conductive material such as carbon/vinyl film, conductive rubber, a metallic foil such as aluminum foil, silver foil, tin foil and copper foil and may be dimensioned to have a diameter that is smaller than a diameter of cover  410 . In one embodiment, the carbon/vinyl film  450  is in contact with front side  410   a  of cover  410 . 
         [0074]    Carbon/vinyl film  450  is formed of a thin flexible sheet of graphite filled polyvinyl chloride film having a thickness of the order of about two to four mils. Carbon/vinyl film  450  is a commercial product available and purchased from Exopack™, LLC, 345 Cedar Springs Ave., Spartanburg, S.C. One skilled in the art may contemplate fabricating carbon/vinyl film  450  from a plurality of suitable materials in accordance with desired applications. 
         [0075]    Electrode assembly  400  is electrically connectable with a first end  492  of a lead wire  490  interposed between cover  410  and carbon/vinyl film  450 . A second end  494  of lead wire  490  extends from a side of electrode assembly  400  and is configured to electrical connection to cable  20 , via a plug, a contact pad/tab or the like. 
         [0076]    Electrode assembly  400  includes a coating of silver/silver-chloride (Ag/AgCl) ink  460  disposed on first or skin side  450   a  of carbon/vinyl film  450 . Ag/AgCl coating  460  is screen printed on skin side  450   a  of carbon/vinyl film  450 . Ag/AgCl coating  460  includes an outer ring or region  462  of continuous 100% coverage or substantially continuous and an inner ring or region  464  of having less than substantially continuous coverage. Ag/AgCl coating  460  defines an open central region  466  that is free of Ag/AgCl ink. In one embodiment, the silver/silver-chloride ink coverage in the inner ring  464  may be about 50%. Silver/silver-chloride ink may be deposited in the inner ring  464  by conventional methods in a desired pattern which may be regular, irregular, random and combinations thereof. In one embodiment, the ink in the inner ring  464  may be a speckle or spray pattern. In another embodiment, the ink in the inner ring may be a regular pattern such as squares, triangles, stripes of similar or varying thickness. The density of the ink applied to the inner ring may vary throughout the region and may form a gradient. For example, the density of the ink in the inner ring may be higher in the region adjacent the central region  466  and lower at one or more locations adjacent the outer ring  462 . Alternatively, the density of the ink may be lower in the region adjacent the central region  466  and higher at one or more locations adjacent the outer ring  462 . 
         [0077]    Outer ring  462  of Ag/AgCl coating  460  is shown as substantially circular including an array of spikes  462   a  therearound extending radially inward, although it is understood that other shapes and cross sectional areas are contemplated depending on a particular use. Outer ring  462  of Ag/AgCl coating  460  extends radially inward to a second diameter that is smaller than the first diameter of cover  410 . The spikes may be sized and shaped for a particular purpose and may, but need not be identical to one another. The spikes may, but need not be spaced equidistantly about the inner periphery of the outer ring. Although the spikes are shown to originate from a V-shape and culminate in at point, the spikes may have a variety of shapes, for example, originating from a U-shape and/or culminating in a rounded or blunt tip. 
         [0078]    Inner ring or region  464  of Ag/AgCl coating  460  is shown as substantially circular and includes an array of spikes  464   a  therearound extending radially inward although other shapes and cross sectional areas are contemplated. Inner ring or region  464  of Ag/AgCl coating  460  extends radially inward to a third diameter that is smaller than the second inner diameter of outer ring  462  and defines the open central region  466  that is free from any coating of Ag/AgCl ink. The spikes may be sized and shaped for a particular purpose and may, but need not be identical to one another. The spikes may, but need not be spaced equidistantly about the inner periphery of the inner ring. Although the spikes are shown to originate from a V-shape and culminate in at point, the spikes may have a variety of shapes, for example, originating from a U-shape and/or culminating in a rounded or blunt tip. 
         [0079]    Ag/AgCl ink is applied in a coating to skin side  450   a  of carbon/vinyl film  450  by conventional methods such as silk screening, flexographic printing spray coating, and transfer coating. The thickness of the Ag/AgCl coating  460  may be any desired thickness suitable for a particular purpose and sufficient to provide good electrical conductivity without substantially impairing the X-ray transparency of the electrode member. Additionally, Ag/AgCl coating  460  has a thickness which does not noticeably effect or change the flexibility of electrode assembly  400 . In one embodiment, the Ag/AgCl coating as a thickness of about ten microns. 
         [0080]    Ag/AgCl coating  460  is composed of about 62% Ag and about 38% AgCl. Such a composition of Ag/AgCl results in a coating of Ag/AgCl having no or insufficient structural integrity on its own and thus is conventionally applied to a backing layer in order to form any pattern. As such, Ag/AgCl coating  460  is not typically an independent layer. Carbon/vinyl film  450 , including coating  460  of Ag/AgCl ink, is inherently radiolucent. One skilled in the art may contemplate using any types of conductive materials in any number of different compositions to achieve desired results. 
         [0081]    Electrode assembly  400  includes a conductive hydrogel  470  defining a first or front side  470   a  facing a subject (not shown) and a second or back side  470   b , opposite first side  470   a  and facing away from the subject, wherein back side  470   b  of hydrogel  470  is in 100% direct contact with front side  450   a  of conductive/vinyl film  450  disposed within open central region  466  of Ag/AgCl coating  460 , in approximately 50% direct contact with skin side  450   a  of conductive/vinyl film  450  disposed in inner ring or region  464  of Ag/AgCl coating  460 , and in 100% direct contact with outer ring or region  462  of Ag/AgCl coating  460 . Hydrogel  470  provides an electromechanical interface between electrode assembly  400  and the subject (not shown). Hydrogel  470  may also adhesively connect electrode assembly  400  to the subject. 
         [0082]    Electrode assembly  400  may include a release liner  480  underlying hydrogel  470  to protect hydrogel  470  prior to use. 
         [0083]    As discussed above, electrode assemblies  100 ,  200 ,  300  and  400  are selectively, electrically connectable to spoon  16  of defibrillation electrode paddle assembly  10 . In particular, electrode assemblies  100 ,  200 ,  300  and  400  are selectively, electrically connectable to cable  20  extending through handle  12  and shaft  14  of defibrillation electrode paddle assembly  10  for electrical connection to a defibrillator monitor (not shown). As so configured, following a surgical procedure or use, electrode assemblies  100 ,  200 ,  300  or  400  are detached from spoon  16  of defibrillation electrode paddle assembly  10  and discarded while defibrillation electrode paddle assembly  10  may be sterilized and/or re-sterilized. 
         [0084]    Additionally, it is contemplated that different combinations of electrode assemblies  100 ,  200 ,  300  and  400  may be used as electrode assembly pairs for use with the pair of defibrillation electrode paddle assemblies  10  depending on the type of effect on the heart desired during the defibrillation. 
         [0085]    In particular, electrode assemblies  100  and  200  may be used to improve conductivity to the center thereof and reduce conductivity to the edges thereof; electrode assemblies  300  and  400  may be used to improve conductivity to the edges thereof and reduce conductivity to the center thereof; or a combination of one electrode assembly  100 ,  200  and one electrode assembly  300 ,  400  in order to establish a degree of directionality to the conductivity. 
         [0086]    It is to be understood that the foregoing description is merely a disclosure of particular embodiments and is in no way intended to limit the scope of the disclosure. Other possible modifications will be apparent to those skilled in the art and are intended to be within the scope of the present disclosure. For example the cover may be formed of a treated or untreated cloth so that the structural strength is creating as the layers are formed or combined. Similarly the Ag/AgCl coating described above may include gradual, continuous density gradient or a step gradient in which each step is uniformly coated. Other configurations of the Ag/AgCl coating contemplated include a cruciform pattern as well as other patterns disclosed in U.S. Pat. No. 7,742,828 issued on Jun. 22, 2010 and entitled Medical Electrode Suitable for High-Energy Stimulation, which is incorporated herein by reference in its entirety for all purposes. Moreover, the handle configuration of the present invention may include switches and/or controls for easy access by the user.