Abstract:
Defibrillator lead designs and methods for improved attachment strength between a fibrosis-limiting material covering, a shocking coil electrode, and an implantable lead body are disclosed herein. In certain examples, a portion of the fibrosis-limiting material extends proximal or distal to a shocking coil end and is disposed between a first and a second lead component. In certain examples, a length of compression tubing is utilized. A chronically implanted lead is often encapsulated by a body&#39;s fibrotic reaction, which in turn causes future lead explantation to be exceedingly difficult. To reduce fibrotic entanglement, the fibrosis-limiting material covering surrounds strategic portions of the lead. Improving the attachment between the fibrosis-limiting material covering, the shocking coil electrode, and the lead body will allow for improved performance, durability, and extractability of the lead. This disclosure describes several defibrillator lead designs and methods to create these improved joints.

Description:
TECHNICAL FIELD 
       [0001]    This patent document pertains generally to implantable defibrillator leads. More particularly, but not by way of limitation, this patent document pertains to the attachment of fibrosis-limiting material to one or more portions of an implantable defibrillator lead. 
       BACKGROUND 
       [0002]    Cardiac and other defibrillation systems typically include an implantable medical device (IMD), such as a pulse generator, electrically connected to the heart by at least one implantable defibrillator lead. More specifically, an implantable defibrillator lead provides an electrical pathway between the IMD, connected to a proximal end of the lead, and cardiac tissue, in contact with a distal end of the lead. In such a manner, electrical stimulation (e.g., in the form of one or more shocks or countershocks) emitted by the IMD may travel through the implantable defibrillator lead and stimulate the heart via one or more exposed, helically wound shocking coil electrodes located at or near the lead distal end portion. Once implanted, the exposed shocking coil electrodes often become entangled with fibrosis (i.e., a capsule of inactive tissue which grows into the exposed coils) with the end result being that a chronically implanted lead can be extremely difficult to remove by the application of tensile force to the lead proximal end. 
         [0003]    Over time, situations may arise which require the removal and replacement of an implanted defibrillator lead. As one example, an implanted defibrillator lead may need to be replaced when it has failed, or if a new type of cardiac device is being implanted which requires a different type of lead system. As another example, bodily infection or shocking coil electrode dislodgement may require the replacement of an implanted defibrillator lead. In such situations, the implanted defibrillator lead may be removed and replaced with one or more different implantable leads. 
         [0004]    To allow for easier removal, some implantable defibrillator leads include a fibrosis-limiting material covering a portion of the one or more otherwise exposed shocking coil electrodes thereon. Unfortunately, current fibrosis-limiting materials are applied to the shocking coil electrodes in ways that lack sufficient attachment strength. As a result, when subjected to shear loads, such as during lead implantation procedures, the fibrosis-limiting material may separate from the associated shocking coil electrode or the shocking coil electrodes themselves may separate from the lead body or deform, thereby leaving uncovered coils that are subject to future fibrotic entanglement. 
       SUMMARY 
       [0005]    Certain examples of the present subject matter include a lead comprising a lead body, at least one shocking coil electrode, and a fibrosis-limiting material. The lead body extends from a lead proximal end portion to a lead distal end portion and may optionally include an inner insulating layer and an outer insulating layer. At least one shocking coil electrode is disposed at one or both of the lead intermediate portion or the lead distal end portion. The fibrosis-limiting material coaxially surrounds, at least in part, the at least one shocking coil electrode and a portion thereof extends proximal or distal to a shocking coil electrode end. This extending portion of the fibrosis-limiting material can be disposed between a first lead component and a second lead component, such as the inner insulating layer and the outer insulating layer of the lead body, for example. 
         [0006]    Certain examples of the present subject matter include a lead comprising a lead body, at least one shocking coil electrode, a fibrosis-limiting material, and a length of compression tubing. The lead body optionally includes an inner insulating layer and an outer insulating layer. The at least one shocking coil electrode is disposed on the lead body and is surrounded, at least in part, by the fibrosis-limiting material. The length of compression tubing extends from a tubing first portion to a tubing second portion. The tubing first portion is disposed over a shocking coil electrode end and the tubing second portion is disposed between a first lead component and a second lead component. 
         [0007]    Certain examples of the present subject matter include a method comprising coaxially fitting a fibrosis-limiting material over at least one shocking coil electrode, forming the fibrosis-limiting material onto an outer surface of the at least one shocking coil electrode, coupling one or more portions of the at least one shocking coil electrode to a lead body or component, and disposing an extending portion of the fibrosis-limiting material between a first lead component and a second lead component. The coaxial fitting of the fibrosis-limiting material over the at least one shocking coil electrode includes positioning the extending portion of the fibrosis-limiting material proximal or distal to a shocking coil electrode end. 
         [0008]    Advantageously, the present leads and methods decrease the likelihood of moving or shifting between a shocking coil electrode and a fibrosis-limiting material covering thereon or between the shocking coil electrode and adjacent portions of a lead body, such as during the lead implantation process. In this way, there is a reduction or elimination of uncovered, implanted shocking coil electrodes that are subject to future fibrotic entanglement, thereby improving the ease of chronic lead extraction should it become necessary. Additionally, the present leads and methods provide smooth transitions at the lead body-shocking coil electrode interface, which also facilitate lead implantation and extractability. These and other examples, advantages, and features of the present leads and methods will be set forth in part in the detailed description, which follows, and in part will become apparent to those skilled in the art by reference to the following description of the present leads, methods, and drawings or by practice of the same. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    In the drawings, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document. 
           [0010]      FIG. 1  illustrates a schematic view of a cardiac defibrillator system, including an IMD and an implantable defibrillator lead, as constructed in accordance with at least one embodiment. 
           [0011]      FIG. 2  illustrates a plan view of an implantable defibrillator lead, as constructed in accordance with at least one embodiment. 
           [0012]      FIG. 3  illustrates an enlarged cross-sectional view of a portion of an implantable defibrillator lead, such as along line  3 - 3  of  FIG. 2 , and an implanted environment, as constructed in accordance with at least one embodiment. 
           [0013]      FIGS. 4A-4C  illustrate an enlarged cross-sectional view of a portion of an implantable defibrillator lead, such as along line  4 - 4  of  FIG. 2 , as constructed in accordance with various embodiments. 
           [0014]      FIG. 5A  illustrates an exploded view of a portion of an implantable defibrillator lead, such as portion  5 A of  FIG. 2 , as constructed in accordance with at least one embodiment. 
           [0015]      FIG. 5B  illustrates an enlarged cross-section view of a portion of an implantable defibrillator lead, such as along line  5 B- 5 B of  FIG. 5A , as constructed in accordance with at least one embodiment. 
           [0016]      FIG. 6  illustrates a schematic view of an implantable defibrillator lead being advanced through an introducer sheath (shown in cross-section), as constructed in accordance with at least one embodiment. 
           [0017]      FIG. 7  illustrates a schematic view of an implanted defibrillator lead being extracted from a patient, as constructed in accordance with at least one embodiment. 
           [0018]      FIG. 8  illustrates a method of attaching a fibrosis-limiting material to one or more portions of an implantable defibrillator lead, as constructed in accordance with at least one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the present leads and methods may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the present leads and methods. The embodiments may be combined, other embodiments may be utilized or structural or logical changes may be made without departing from the scope of the present leads and methods. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present leads and methods is defined by the appended claims and their legal equivalents. 
         [0020]    In this document, the terms “a” or “an” are used to include one or more than one, and the term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. 
         [0021]    Fibrosis-limiting material coverings for shocking coil electrodes facilitate the extractability ease of chronically implanted defibrillator leads. Unfortunately, the nature of fibrosis-limiting materials and previous manufacturing methods to attach such materials to the shocking coil electrodes lack in physical strength. As one example, certain fibrosis-limiting materials, such as expanded polytetrafluoroethylene (ePTFE), resist adhesion due to their chemical nature and require extremely high heat to sinter to a shocking coil electrode. This high heat exceeds temperatures that many lead body materials can withstand. For at least this reason, previous shocking coil electrodes that are partially surrounded by a fibrosis-limiting material are typically attached to a lead body solely at their very ends using, for example, a medical adhesive. 
         [0022]    It has been found that when implanting such previously manufactured defibrillator leads, high drag forces are created along the lead body (e.g., due to an introducer seal of a hemostatic introducer). As a result, several lead component interfaces, including the fibrosis-limiting material to shocking coil electrode and the shocking coil electrode to lead body, have a tendency to separate or shift relative to one another leaving one or more uncovered coils. Advantageously, the present leads and methods provide improved attachment strength between the fibrosis-limiting material, the shocking coil electrodes, and the lead body, and as a result, reduce or eliminate the presence of uncovered, implanted shocking coil electrodes which are subject to future fibrotic entanglement. 
         [0023]      FIG. 1  illustrates a schematic view of a cardiac defibrillator system  100 , which is useful for the correction of tachycardia or fibrillation, among other things. The system  100  includes an IMD  102  and at least one implantable defibrillator lead  104 . As shown, the implantable defibrillator lead  104  includes a lead body  120  extending from a lead proximal end portion  106 , coupled with the IMD  102 , to a lead distal end portion  108  implanted within, on, or near a heart  114 , with a lead intermediate portion  116  therebetween. The lead intermediate portion  116  or the lead distal end portion  108  includes at least one shocking coil electrode  110  thereon. In this example, the at least one shocking coil electrode  110  is surrounded by a fibrosis-limiting material  112 . In various examples, the fibrosis-limiting material  112  comprises a thin, polymeric layer coaxially surrounding and contacting an outer surface  370  ( FIG. 3 ) of the helically wound shocking coil electrode  110 . 
         [0024]    The implantable defibrillator lead  104  transmits electrical signals between a selected location within, on, or about the heart  114  and the IMD  102 , such as to monitor the heart&#39;s  114  electrical activity at the selected location or to carry stimulation signals (e.g., one or more shocks or countershocks) to the selected location from the IMD  102 . The implantable defibrillator lead  104  may include a fixation assembly, such as one or more tines  118  or a helical coil, to anchor the lead distal end portion  118  at the selected located. The one or more tines  118  may be formed as part of the lead body  120 , and thus may include a biocompatible lead body material, such as silicone rubber, polyurethane, polyimide, or a non-porous fluoropolymer. 
         [0025]      FIG. 2  illustrates a plan view of an implantable defibrillator lead  104 . As shown, the implantable defibrillator lead  104  includes a lead body  120  extending from a lead proximal end portion  106  to a lead distal end portion  108  and having a lead intermediate portion  116  therebetween. In various examples, the lead body  120  includes an inner insulator layer  202 , such as silicone rubber or other layer of impermeable polymeric electrically insulating material, and an outer insulator layer  204 , such as polyurethane which provides high abrasion resistance. 
         [0026]    In this example, the lead intermediate portion  116  and the lead distal end portion  108  include a first and a second shocking coil electrode  110 . The first and second shocking coil electrodes  110  comprise an uninsulated, helically wound shocking coil formed of a non-corrosive, bio-compatible metal, such as platinum, titanium, or alloys (e.g., platinum/iridium). The shocking coil electrodes  110  are covered by a pliable fibrosis-limiting material  112  (e.g., polytetrafluoroethylene (PTFE) or expanded PTFE (ePTFE)) in direct contact with an outer surface  370  ( FIG. 3 ) of the shocking coil electrode  110 . The implantable defibrillator lead  104  of this example further comprises a distal tip electrode  210 . The distal tip electrode  210  may be porous and include a metallic mesh. One or more conductors in the lead body  120  electrically and mechanically couple the electrodes  110 ,  210  to the lead proximal end portion  106 . The conductors may be of any structure or combination of structures, such as coaxial or coradial coils separated by an insulating tube, or side-by-side cables or coils separated by a polymer, such as fluoropolymer, silicone, polyimide, or polyurethane. 
         [0027]    As shown, but as may vary, the lead proximal end portion  106  includes three terminal leg connections  206  each of which is sized and shaped to couple to respective connector cavities incorporated into a header of the IMD  102  ( FIG. 1 ). It is through the coupling between the lead proximal end portion  206  and the connector cavities that the electrodes  110 ,  210  are electrically coupled to electronic circuitry within the IMD  102 . While  FIG. 2  illustrates an implantable defibrillator lead  104  having three terminal connections  206  and three electrodes  110 ,  210 , the present leads may vary, such as by including more or less than three terminal connections  206  and electrodes  110 ,  210 . 
         [0028]      FIG. 3  illustrates an enlarged cross-sectional view, such as along line  3 - 3  of  FIG. 2 , of a shocking coil electrode  110  surrounded by a thin, fibrosis-limiting material  112 . As shown in this example, the fibrosis-limiting material  112  may be drawn into the coil gaps  302 , such as via a heat sintering process, thereby eliminating or reducing the air volume present in the gaps. This tight conformation between the fibrosis-limiting material  112  and the shocking coil electrode  110  results in good electrical energy transmission  350  from the coil  110  to surrounding cardiac tissue. The use of the fibrosis-limiting material  112  as the tissue contacting portion of the shocking coil electrode  110  prevents fibrotic tissue ingrowth (as shown), which is often seen as a disadvantage of leads relying on direct contact between an exposed portion of a coil electrode and living tissue. 
         [0029]    Options for the fibrosis-limiting material  112  are numerous. For instance, the fibrosis-limiting material  112  may include PTFE, ePTFE, or other non-biodegradable and biocompatible materials, such as expanded ultra-high molecular weight polyethylene (eUHMWPE); may either be porous or non-porous; or may be inherently conductive or rely on porosity in conjunction with bodily fluids to be conductive. In various porous examples, the pore size is adequately small to allow penetration of conductive bodily fluids while substantially precluding tissue ingrowth, thus allowing a less traumatic removal of the defibrillator lead  104  after implantation should extraction become necessary. In various other examples, electrical conductivity through the fibrosis-limiting material  112  is not based on porosity, but rather is inherent in the material  112  as described in commonly-assigned Krishnan, U.S. Pat. No. 7,013,182 titled “CONDUCTIVE POLYMER SHEATH ON DEFIBRILLATOR SHOCKING COIL,” which is hereby incorporated by reference in its entirety. 
         [0030]    Turning now to  FIGS. 4A-4C , various techniques for robustly attaching the fibrosis-limiting material  112  to one or more portions of an implantable defibrillator lead  104  are disclosed. These FIGS. illustrate an enlarged cross-sectional view of an implantable defibrillator lead  104 , such as along line  4 - 4  of  FIG. 2 , including a lead body  120 , a shocking coil electrode  110 , and a fibrosis-limiting material  112 . The lead body  120  in these examples includes an inner insulator layer  202  and an outer insulator layer  204 , the latter of which abuts an end of the helically wound shocking coil electrode  110 . As shown, the fibrosis-limiting material  112  coaxially covers portions of the shocking coil electrode  110  in a tightly conforming manner. 
         [0031]    In  FIG. 4A , a tightly-wound shocking coil electrode  110  is utilized in conjunction with a length of compression tubing  402 . The tightly-wound nature of the shocking coil electrode  110  may prevent or reduce axial movement of coil fibers which may occur with a loosely-wound shocking coil (i.e., a coil with spacing between the coil filars); however, the attachment technique of  FIG. 4A  may also be used with a loosely-wound coil. In this example, a tubing first portion  404  is placed over an end of shocking coil electrode  110 , and in some examples, the fibrosis-limiting material  112 , while a tubing second portion  406  is disposed between the first  202  and second  204  insulating layers of the lead body  120 . In certain examples, the compression tubing  402  comprises silicone or other tubing having an inner diameter smaller than an outer diameter  372  ( FIG. 3 ) of the shocking coil electrode  110  prior to being disposed therearound. In such examples, the tubing  402  is temporarily expanded and placed over the coil  110  and the fibrosis-limiting material  112  end regions, thereby mechanically holding the same in place. In this way, plastic deformation of the shocking coil electrode  110  and relative movement of the fibrosis-limiting material  112  relative to the coil  110  is reduced or eliminated, such as during lead implantation procedures. 
         [0032]      FIG. 4B  illustrates an attachment technique including a tightly-wound shocking coil electrode  110  in conjunction with a fibrosis-limiting material  112  having one or more ends which extend proximal or distal to an end of the coil  110 . While a tightly-wound shocking coil electrode  110  is illustrated, the attachment technique of  FIG. 4B  may also be used with a loosely-wound coil. The over-extension  408  of the fibrosis-limiting material  112 , in this example, is disposed between the inner  202  and outer  204  insulating layers of the lead body  120 , thereby holding the ends of the shocking coil electrode  110  and the fibrosis-limiting material  112  in place and not exposing portions of the shocking coil to future fibrotic entanglement. Additionally, stretching of the shocking coil electrode  110  is less likely to occur during lead implantation process using this technique, as an introducer sheath  600  ( FIG. 6 ), specifically an introducer seal  604  ( FIG. 6 ), is less likely to catch and pull a portion of the coil  110 . 
         [0033]    As illustrated in  FIGS. 5A and 5B , the over-extension  408  (shown in cross-section) of the fibrosis-limiting material  112  past the shocking coil electrode  110  may alternatively be disposed between two or more crimp or weld rigid (or semi-rigid) structures, such as an annular partial band or ring member  504  and an annular core member  502 . In various examples, the annular partial band or ring member  504  and the annular core member  502  are used to secure an over-extension  408  of the fibrosis-limiting material  112  at a distal end of the defibrillator lead  104  ( FIG. 2 ). 
         [0034]    In  FIG. 4C , a combination of the embodiments shown in  FIGS. 4A and 4B  is utilized as an attachment technique between the shocking coil electrode  110 , the fibrosis-limiting material  112 , and the lead body  120 . More specifically, the attachment technique of this example includes a tightly-wound shocking coil electrode  110  in conjunction with a length of compression tubing  402  and an over-extending fibrosis-limiting material  112 . While a tightly-wound shocking coil electrode  110  is illustrated, the attachment technique of  FIG. 4C  may also be used with a loosely-wound coil. As shown, a first portion  404  of the compression tubing  402  is placed over an end of shocking coil electrode  110 ; while a second portion  406  of the compression tubing  402  is disposed between the first  202  and second  204  insulating layers of the lead body  120 . The over-extension  408  of the fibrosis-limiting material  112  is disposed between the inner insulator  202  of the lead body  120  and the second portion  406  of the compression tubing, thereby holding the ends of the shocking coil electrode  110  and fibrosis-limiting material  112  in place and not exposing portions of the shocking coil electrode to future fibrotic entanglement. Although not shown, the disposition of the compression tubing  402  and the over-extension  408  of the fibrosis-limiting material  112  may be interchanged. 
         [0035]    Advantageously, the techniques shown in  FIGS. 4A-4C  provide robust mechanical attachment between the fibrosis-limiting material  112 , the shocking coil electrode  110 , and the lead body  120 , yet do not compromise the flexibility of the defibrillator lead  104 . In this way, the present attachment techniques allow for long flex life to accommodate interaction with a beating heart  114  ( FIG. 1 ). Prototypes have shown that the manufacturing of these attachment techniques may be accomplished and that the strength of the shocking coil electrode  110  and the fibrosis-limiting material  120  to lead body  120  attachment is improved relative to previously-used attachment schemes. 
         [0036]    Implantable defibrillator leads  104  are often placed in contact with cardiac tissue by passage through a venous access, such as the subclavian vein, the cephalic vein, or one of its tributaries. In such a manner, an implantable defibrillator lead  104  may advantageously be placed in contact with the heart  114  ( FIG. 1 ) without requiring major thoracic surgery. Instead, an implantable defibrillator lead  104  may be introduced into a vein and maneuvered therefrom into contact with the heart  114  or tissue thereof. A multi-step procedure is often required to introduce implantable defibrillator leads  104  within the venous system. Generally, this procedure consists of inserting a hollow needle into a blood vessel, such as the subclavian vein. A guide wire is then passed through the needle into the interior portion of the vessel and the needle is withdrawn. As illustrated in  FIG. 6 , an introducer sheath  600  with a dilator assembly  602  may be inserted over the guide wire into the vessel for lead  104  introduction. The sheath  600  is advanced to a suitable position within the vessel, such that a distal end thereof is well within the vessel, while a proximal end thereof is outside the patient. 
         [0037]    When a physician implants a defibrillator lead  104 , such as through the introducer sheath  600  and specifically an introducer seal  604 , high drag forces may be created along the lead body  120 . As a result of these high drag forces, previous lead component interfaces including the fibrosis-limiting material  112  to shocking coil electrode  110  and the shocking coil electrode  110  to the lead body  120  tended to separate or shift relative to one another leaving uncovered coil portions subjected to future fibrotic entanglement (e.g., the shocking coil electrode  110  became stretched, which in turn pulled the fibrosis-limiting material  112  away from the coil  110  and exposed a portion of the coil to fibrotic growth). Using the present attachment techniques, it has been found that such separating or shifting between the fibrosis-limiting material  112 , the shocking coil electrode  110 , and the lead body  120  is reduced or eliminated, thereby preventing fibrotic entanglement and facilitating lead extraction should it become necessary. 
         [0038]      FIG. 7  illustrates a lead extraction device  700 . In this example, the lead extraction device  700  includes a weight  702  coupled over a pulley  704  to a proximal end  106  of an implanted defibrillator lead  104  to be removed from a patient  706 . By minimizing or preventing the fibrotic entanglement with the shocking coil electrode  110  ( FIG. 3 ), the implanted defibrillator lead  104  may be removed from the patient  706  with relatively small amounts of tensile force (e.g., applied via the weight  702 ) and reduced time. The lead removal process is therefore relatively atraumatic and is considered to be easily extracted from the patient  706  within which it has been implanted. 
         [0039]      FIG. 8  illustrates a method  800  of manufacturing an implantable defibrillator lead including secure, robust attachment between a fibrosis-limiting material, a shocking coil electrode, and a lead body. At  802 , a fibrosis-limiting material is coaxially fit over at least one shocking coil electrode. In various examples, this coaxially fitting includes positioning a portion of the fibrosis-limiting material proximal or distal to a shocking coil electrode end. At  804 , the fibrosis-limiting material is formed onto an outer surface of the at least one shocking coil electrode, such as through the use of heat. At  806 , one or more portions, such as end portions, of the at least one shocking coil electrode are coupled to a lead body or component. Optionally, the coupling between the shocking coil electrode and the lead body includes the use of an adhesive. 
         [0040]    At  808 , the proximal or distal portion of the fibrosis-limiting material is disposed between a first lead component and a second lead component. In one example, this disposition between the first and the second lead component includes disposing the fibrosis-limiting material between a lead body inner insulating layer and a lead body outer insulating layer. In another example, the disposition between the first and the second lead component includes disposing the fibrosis-limiting material between a rigid or semi-rigid core member and a rigid partial band or ring member sized and shaped to couple around the rigid core member. Optionally, at  810 , a length of compression tubing is disposed between the at least one shocking coil electrode and the fibrosis-limiting material on a tubing first portion and between a lead body inner insulating layer and the fibrosis-limiting material on a tubing second portion. 
         [0041]    Leads and methods for improved attachment strength between a fibrosis-limiting material, a shocking coil electrode, and a lead body are discussed. Advantageously, the present leads and methods decrease the likelihood of moving or shifting between such components and, in this way, reduces or eliminates the presence of uncovered, implanted shocking coil electrodes subjected to future fibrotic entanglement. Additionally, the present leads and methods provide smooth transitions at the lead body-shocking coil electrode interface, which facilitate lead implantation and extractability. 
         [0042]    It is to be understood that the above description is intended to be illustrative, and not restrictive. For instance, any of the aforementioned examples may be used individually or with any of the other examples. In addition, the aforementioned examples may or may not include the use of adhesives (e.g., medical adhesives) for selected component attachment. Many other embodiments may be apparent to those of skill in the art upon reviewing the above description. The scope of the present leads and methods should, therefore, be determined with reference to the appended claims, along with the full scope of legal equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, assembly, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of such claim. 
         [0043]    The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together to streamline the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may lie in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.