Abstract:
Method and apparatus for treating obesity by an energy delivery device, such as a high focus ultrasound transducer, mounted for movement along two or three axes relative to the esophagus to deliver transesophageal energy to interrupt the function of vagal nerves. Preferably, movement along a longitudinal axis of the esophagus changes the site to which the energy is directed and movement transversely along a radius of the esophagus focuses the energy on a vagal nerve. The third degree of freedom relative to the esophagus is to rotate the transducer about the longitudinal axis of the esophagus.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/389,236, titled “Methods and Apparatus for Treatment of Obesity,” filed Mar. 14, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The field of the present invention is methods and devices for treating obesity, and more particularly, methods and devices for treating obesity by disrupting the vagal nerve.  
       BACKGROUND OF THE INVENTION  
       [0003]     Obesity has become an ever-increasing health problem. While such voluntary weight reduction programs as dieting and exercise have been helpful for some, many obese persons have required surgery to address their obesity problem. Two such surgical procedures are vertical banded gastroplasty (VBG) and the Roux-en-Y gastric bypass procedure. Both such procedures are now well known, but they are invasive in nature and involve reducing the size of the stomach. While these procedures have demonstrated a reasonable level of efficacy, there is a need for an improvement in the treatment of obesity that would avoid invasive surgery and providing an effective treatment of obesity.  
       SUMMARY OF THE INVENTION  
       [0004]     The invention is, in general, directed to the treatment of obesity by creating an interruption of the vagal nerve, preferably in the region of the esophagus, by minimally or noninvasive means. While the present invention is not to be tied to any particular theory of operation, it appears that a hunger signal is expressed by ghrelin, a peptide primarily produced in the stomach, and transmitted to the brain through the vagal nerve. The literature e.g., “The Role of the Gastric Afferent Vagal Nerve in Ghrelin-Induced Feeding and Growth Hormone Secretion in Rats,”  Gastroenterology  2002:123:1120-1128 (October 2002) by Yukari Date et al. and “Gastroplasty for Obesity: Long-term Weight Loss Improved by Vagotomy,”  World Journal of Surgery , Vol. 17, No. 1, January/February 1993, by Kral et al., supports this theory. The Date et al. article concluded that blockade of the gastric vagal afferent abolished ghrelin-induced feeding in rats and the Kral et al. article concluded that vagotomy combined with gastroplasty was more effective in controlling weight loss than gastroplasty alone. These articles are incorporated by reference herein.  
         [0005]     More specifically, the preferred embodiment of the invention uses an ultrasound device that is movable along up to three axes. In particular, the preferred embodiment has an ultrasound device may be moved longitudinally along the axis of the esophagus to a further or closer distal position, transversely along the radius of the esophagus, and rotationally about the axis of the esophagus. These three degrees of freedom are relative to the esophagus. Because the ultrasound device is movable along the radial axis, the device is better able to focus its energy output on the vagal nerve in the region of the esophagus to interrupt the function of the vagal nerve, while avoiding injury to the esophagus. After an ablating or other nerve dysfunction causing device installed in the esophagus is properly positioned, it may be used to deliver ablating energy to one or more vagal nerve branches in a transesophageal manner. The anatomy of the vagal nerve complex varies somewhat from person to person, but, common to all is a structure comprising multiple vagal nerve branches located on the outer wall of the esophagus which run generally longitudinally along the esophagus wall. The preferred embodiment contemplates interrupting the function of one or more vagal nerve branches in a transesophageal manner by using various types of energy including radio frequency (RF) energy, high intensity ultrasound, high intensity focused ultrasound, and other types of energy as described in more detail below.  
         [0006]     Typically, there are two main branches, or trunks, of the vagal nerve which are located approximately 180° from each other on the outer wall of the esophagus. Depending on patient needs, it may be sufficient to interrupt only a portion of the fibers in the nerve. In this regard, it is to be noted that, in general, myelinated vagal nerve fibers, i.e., fibers that have an outer coating, are efferent. In contrast, afferent vagal nerves are unmyelinated and have no outer covering. For some patients, it may be sufficient to interrupt the function of only the afferent vagal fibers. However, the invention can be used to disrupt the vagal nerve at other locations, such as at the diaphragm.  
         [0007]     The objective is, of course, weight loss by the patient as a result of interruption of efferent gastric and afferent hormonal signals transmitted through the vagal nerve branches. Thus, the success of the procedure described herein will, to some extent, be patient-dependent and, in some patients, it may be necessary to interrupt both the afferent and efferent vagal fibers, both of which may be found in the posterior and anterior branches.  
         [0008]     In practicing the present invention, the energy source may be installed in the esophagus through the throat, but nasogastric access through the nose and extracorporeal application are also contemplated. The energy may be delivered to the vagal nerve through the esophagus wall, e.g., when ultrasound is used, or by causing an energy delivery device, e.g., an electrode to be passed through the wall of the esophagus.  
         [0009]     Still other energy sources can be used to interrupt the function of the vagal nerves including thermal, microwave, laser and cryogenic energy. Alternatively, the vagal nerve function can be interrupted by transesophageal delivery of a neurotoxin such as capsaicin, atropine, or botulinum toxin. Still further, mechanical means can be used to crush the vagal nerve, e.g., with a clip or pincer, or the vagal nerve can be cut transesophageally with an appropriate cutting instrument. In a preferred embodiment of the present invention, the vagal nerve will be interrupted in the vicinity of the zig-zag line, also known as the Z-line, which is generally located in the lower esophagus between the cardiac notch of the stomach and the diaphragm.  
         [0010]     Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. It is also intended that the invention is not limited to require the details of the example embodiments. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0011]     The details of the invention, including fabrication, structure and operation, may be gleaned in part by study of the accompanying figures, in which like reference numerals refer to like segments. The figures are not to scale and the size of the features in relation to each other is not intended to limit the invention in any way.  
         [0012]      FIG. 1  is a diagrammatic illustration of the general anatomy of the stomach and esophagus.  
         [0013]      FIG. 2  illustrates positioning of an ablation device using a single balloon installed above the diaphragm.  
         [0014]      FIG. 3  illustrates positioning the ablation device using a balloon which is inflated in the stomach.  
         [0015]      FIG. 4  illustrates a positioning device using radially extending feet.  
         [0016]      FIG. 5  illustrates a positioning device using a bite block.  
         [0017]      FIG. 6  is a diagrammatic illustrate of the use of needles or electrodes to detect and ablate around the circumference of the outer surface of the esophagus in a manner designed to interrupt all vagal nerve branches.  
         [0018]      FIG. 7  is an illustration of an ablating device which ablates a sector of the circumference of the outer wall of the esophagus.  
         [0019]      FIG. 8  shows ablating at multiple levels.  
         [0020]      FIG. 9  illustrates an ablation ring which can be adjusted to ablate at different angles relative to the access of the esophagus.  
         [0021]      FIG. 10  illustrates the use of still another ablation device to locate and interrupt the vagal nerve.  
         [0022]      FIG. 11  illustrates an endoluminal burge test which can be used to determine the extent of ablation accomplished.  
         [0023]      FIG. 12  shows an ultrasound ablating device which may be used according to the present invention.  
         [0024]      FIG. 13A  illustrates an ultrasound device installed in the esophagus.  
         [0025]      FIG. 13B  illustrates the stomach and esophagus with an elongate device with a D-shaped distal tip.  
         [0026]      FIG. 13C  illustrates a cross section of the esophagus of  FIG. 13B  to show the D shaped distal tip inside the esophagus.  
         [0027]      FIG. 14  illustrates an ablation device installed in the esophagus in a manner which shows the esophasgus held in its naturally relaxed configuration by a transducer device.  
         [0028]      FIGS. 15 and 16  illustrate an alternative to the device shown in  FIG. 14 .  
         [0029]      FIG. 17A  illustrates a perspective view of a preferred embodiment of the present invention when the ultrasound transducer platform is in a fully lowered position.  
         [0030]      FIG. 17B  illustrates a perspective view of a preferred embodiment of the present invention when the ultrasound transducer platform is in a fully raised position.  
         [0031]      FIG. 18  illustrates a perspective view of a preferred embodiment of the transducer platform.  
         [0032]      FIG. 19  illustrates a perspective view of a preferred embodiment of a position actuator.  
         [0033]      FIG. 20  illustrates an example of the focal point and distribution of energy emitted from the ultrasound transducer.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]     Before turning to the manner in which the present invention functions, it is believed that it will be useful to briefly review the anatomy of the stomach and the esophagus. The esophagus is a muscular tube that carries food from the throat to the stomach and which passes through the diaphragm. The top end of the esophagus is the narrowest part of the entire digestive system and is encircled by a sphincter (circular muscle) that is normally closed but can open to allow the passage of food. There is a similar sphincter at the point where the esophagus enters the stomach. The walls of the esophagus consist of strong muscle fibers arranged in bundles, some circular and others longitudinal. The inner lining of the esophagus consists of smooth squamous epithelium (flattened cells).  
         [0035]     As shown in  FIG. 1 , the esophagus  1  extends through the diaphragm  2  into the stomach  3 . Vagal nerve branches extend from the stomach along the outer wall of the esophagus to the brain. At the lower end of the esophagus, the juncture of the esophageal and gastric mucosa forms a zig-zag line  4 , usually referred to as the Z-line. In the area extending from the diaphragm to a point below the Z-line, there is a subhiatal fat ring which surrounds the outer wall of the esophagus. The vagal nerve branches run between the outer wall of the esophagus and the hiatal fat ring in this area. This anatomy is well understood by those skilled in the art and a more detailed description can readily be found in a standard work such as Gray&#39;s Anatomy.  
         [0036]      FIG. 2  illustrates in a diagrammatic manner an ablation device  5  which is held in place by balloon  6  which is inflated inside the upper portion of the esophagus.  FIG. 3  illustrates positioning the ablation device  5  with balloon  7  which is inflated inside stomach  3 .  FIG. 4  illustrates positioning the ablation device  5  with feet  6  which pass through the esophagus folded against the ablation device  5  and then are extended inside stomach  3 .  FIG. 5  illustrates the use of a bite block  7  to position the ablation device  5  in stomach  3 .  FIG. 6  is a diagrammatic transverse cross section of the esophagus showing, in diagrammatic form, the esophagus wall  1 , vagal nerve branches  8 , a detection/ablation device  9  having needle probes  10 . As shown, the needle probes  10  extend through the wall of the esophagus and can be used both to locate the vagus nerve and to ablate it. For detection purposes, the needle probes  10  are connected to an exterior control unit that detects and displays nerve activity in a manner well known to those skilled in the art. Once a vagal nerve is detected by a needle probe by sensing the activity of the nerve upon contact, the adjacent needle probes are energized and act in the manner of bipolar cautery probes which ablate the nerve and any other tissue between the needle probes. Preferably, the needle probes are designed in such a manner that they are held within the body of the ablation device until the device reaches its desired location. The needle probes can then be extended to penetrate the wall of the esophagus once the device has been positioned. Preferably, the needle probes are designed so that the electric current flows only at their tips so that the depth of the cautery can be focused to minimize damage to the esophagus. Cosman U.S. Pat. No. 4,565,200, Rydell U.S. Pat. No. 5,007,908, Edwards U.S. Pat. No. 5,370,675 and Edwards U.S. Pat. No. 6,129,726, each of which is incorporated by reference herein, disclose various types of electrode needle probe devices which can be used to deliver RF energy to tissue located within the body. Each of these patents discloses a device in which the needle probes are contained within the device until it has reached its desired location, at which time the needle probes are deployed to contact the tissue to which energy is to be delivered.  
         [0037]     In the present invention, the needle probes can irradiate around the complete circumference of the device as shown in  FIG. 6  or from only a portion of the device as shown in  FIG. 7 . If the latter, the device can be rotated sequentially to ensure complete coverage. As further shown in  FIG. 7 , when the needle probes  13  radiate from only a portion of the circumference of the device  12 , a back balloon  11  can be used to position the device  12  in the desired location.  
         [0038]      FIG. 10  illustrates an alternative sector-specific ablation device in which needle probes  13  are activated by device  12  to locate and ablate the vagal nerve in the manner described above. If a patient can obtain the desired benefit of obesity reduction by ablating the two main vagus branches  8 , the procedure is simplified and the amount of ablation necessary is reduced. On the other hand, as shown in  FIG. 8 , if multiple ablation levels  14  are found to be necessary to provide the desired benefit to the patients, more than one ablation can be performed.  
         [0039]     If the patient&#39;s anatomy makes it desirable, an ablation device  5  can be provided with an energy delivery component  15  which is adjustable such that energy can be delivered perpendicularly to the probe or at an angle to the probe.  
         [0040]     When a needle probe is used to deliver energy according to the present invention, the device can be provided with temperature sensors such as thermocouples which are disposed in the distal region of the needle probes. The needle probes can be formed of a variety of materials including nickel-titanium alloy. The needle probes can assume a linear or curved shape when deployed. The device may also be provided with means for cooling the treatment site with a suitable fluid such as water, air, or other liquid or gas, to control the temperature at the treatment site. Thus, the temperature sensor can either cause a cooling medium to be provided or shut off the delivery of energy through one or more needle probes.  
         [0041]     In a preferred embodiment of the present invention, high intensity focused ultrasound (HIFU) is used to ablate the vagal nerve branches. The HIFU energy can be transmitted transesophageally to ablate the vagal nerves on the outer wall of the esophagus.  
         [0042]      FIG. 12  illustrates in a diagrammatic form an ultrasound device which can be used according to the present invention. As shown, the device comprises an elongated member  16  which has an ultrasound transducer  17  mounted on its distal region. The elongated member is positioned in a housing  18  which is provided with an inflatable balloon  19 . This device may be installed by passing it through the throat and down the esophagus until it reaches its desired location with the balloon  19  deflated. Xray, magnetic resonance imaging, or other known imaging techniques may be used to ascertain the positioning of the treatment device  50 , or any other device described herein, in the gastroesophageal region, including axially down the esophagus and rotationally toward the anterior vagus nerve trunk. After rotating the treatment device  50 , for example by 180 degrees to target the posterior vagus nerve trunk, the new position of the device  50  may be confirmed by xray, magnetic resonance imaging, or other known imaging techniques. The balloon  19  can then be inflated to position the device and the ultrasound transducer can be activated to transmit energy radially outwardly. Alternatively, a vacuum device can be used to position the housing.  
         [0043]     As shown in  FIGS. 17A and 17B , the preferred embodiment of the present invention uses an ultrasound device  54  in a treatment device  50  that is movable along two axes. The treatment device  50  preferably treats obesity by disrupting the gastric vagal nerve adjacent the esophagus. In this example embodiment, a movable platform  52  carries a high focus ultrasound (HIFU) transducer device  54 . The transducer  54  may be have an air-backing  55 , or other types of known transducer backing materials.  FIG. 17A  illustrates a perspective view of the preferred embodiment when the platform  52  is in a fully lowered position, while  FIG. 17B  illustrates a perspective view when the platform  52  is in a fully raised position. Of course, the ultrasound transducer  54  may move anywhere between the fully raised position and the fully lowered position. Thus, the platform  52  may move the ultrasound transducer  54  closer to or farther from a treatment window  72  so as to control the focal point of the energy output from the ultrasound transducer  54 . As the ultrasound transducer  54  moves farther from the treatment window  72 , the focal point of the energy from the ultrasound transducer  54  moves closer to the wall of the esophagus.  FIG. 20  illustrates an example of the focal point  90  and distribution  92  of energy emitted from the ultrasound transducer. Thus, the focal point  90  is adjustable. Preferably, the focal point  90  is directed at the site of a vagal nerve and away from the esophagus wall.  
         [0044]      FIG. 18  illustrates a perspective view of an example embodiment of the transducer platform  52 . The platform  52  preferably carries a high intensity focused ultrasound transducer  54  and an ultrasound imaging transducer  56 . The ultrasound imaging transducer  56  performs diagnostic imaging for monitoring the formation of lesions in the esophagus and for defining the outside of the esophagus for the purpose of locating the vagal nerve. The ultrasound imaging transducer  56  can be any known type of imaging transducer such as those that are mechanically based (e.g., rotating and pivoting transducers) or piezo electrically based phased arrays, which have, for example, 128 imaging transducers.  
         [0045]     The platform  52  also may include circulation channels  58  for allowing fluid, such as saline, to flow into the device and around the ultrasound transducer  54  so as to improve the acoustic characteristics of the ultrasound transducer  54  or to cool the transducer  54 . Even though the transducer  54  is illustrated as having a curved surface, the ultrasound transducer  54  may have any geometry, size, shape and curvature as appropriate.  
         [0046]     The platform  52  has one or more guide rails or guide bosses  60 , which couple to guide slots  62  of the position actuator  64  shown in  FIG. 19 , which illustrates a perspective view of an example embodiment of the position actuator  64 . Because the guide bosses  60  ride in upward slanted guide slots  62 , movement of the distal end  88  of the position actuator  64  toward the platform  52  causes the platform  52  to rise toward the treatment window  72 . The upper limit stops  70  on the platform  52  create an upper limit of motion for the platform  52 . Of course, variations are also contemplated. For example, the guide slots  62  can be in a falling configuration so that movement of the distal end  88  of the position actuator  64  toward the platform  52  causes the platform  52  to retreat from the treatment window  72 . As another example, guide bosses  60  and guide slots  62  may be replaced by any other known mechanism, such as gears, levers or a set of guide rails, to translate the platform  52  toward and away from the treatment window. The guide bosses  60  may be on two or more sides of the platform  52 , which would require guide slots  62  on two or more corresponding sides of the position actuator  64 . The upper limit stops  70  could hang from the inner surface of the wall having the treatment window  72  instead of being on the platform  52 .  
         [0047]     As shown in  FIG. 19 , the position actuator  64  has an elongate member  66  so the physician can push the actuator  64  distally or pull the actuator  64  proximally. A forward stop  74  defines the furthest distal position that the position actuator  64  may be moved.  
         [0048]     Turning to  FIG. 17A , the platform  52  is shown in its fully lowered position. As such, the forward stop  74  of the position actuator  64  is not engaged with corresponding stop  76  in treatment device  50 .  FIG. 17A  also illustrates a nerve mapping device  80 , which is preferably a 10×10 constant current impedance grid for nerve mapping. A thermocouple  71  to monitor the mucosal layer may also be provided on the outer surface of the treatment device  50 .  
         [0049]     An inflow channel  84  and outflow channel  86  may be provided so that fluids, such as saline, may flow through the treatment device  50 . Additionally, optional micro holes  87  may be provided in the wall of the treatment device  50  to facilitate the flow of fluids into and out of the device  50 .  
         [0050]     Comparing  FIG. 17A  to  FIG. 17B , one will see that the position actuator  64  in  FIG. 17B  is fully inserted so that the forward stop  74  has engaged corresponding stop  76 , and the platform  52  is fully raised. Therefore, in this example preferred embodiment, moving the position actuator  64  distally relative to the treatment device  50  causes the platform  52  to move toward the treatment window  72 . Conversely, in this example preferred embodiment, moving the position actuator  64  proximally relative to the treatment device  50  causes the platform  52  to move away from the treatment window  72 . Thus, the treatment device  50  permits the position of the ultrasound transducer  54  relative to the treatment window  72 , and thus, the esophageal wall, to be adjusted. The adjustable positioning of the ultrasound transducer  54  along this axial axis permits control over the focusing of the energy emitted from the ultrasound transducer  54  onto the gastric vagal nerve in the region of the esophagus while minimizing damage to or burning of the esophageal wall.  
         [0051]     Besides translation along the axial axis, the platform  52  and ultrasound transducer  54  may be moved longitudinally along another axis to a further or closer distal position. Because the ultrasound transducer  54  can be moved longitudinally, e.g., closer or further from the stomach, the treatment device  50  can be more accurately positioned to ablate or otherwise disrupt the vagal nerve. Moreover, the treatment device  50  may be used to deliver ablating energy to one vagal nerve branch in a transesophageal manner, and then moved to another vagal nerve branch for further disruption of the vagal nerve system or for testing the completeness of the prior disruption of the vagal nerve.  
         [0052]     A preferred method of disrupting the vagal nerves is as follows: First, a treatment device  50 , or any other device described herein, is positioned at the appropriate location in the esophagus, preferably with the assistance of xray, magnetic resonance imaging, or other known imaging techniques. Such imaging techniques may be used to properly position the treatment device axially down the esophagus and rotationally toward the anterior vagus nerve trunk. Then the inner esophagus is cooled and the ablation depth is adjusted with an imaging crystal along a radial line of the esophagus. High level energy is emitted from the treatment device, such as from a HIFU transducer, to ablate and disrupt the anterior vagal nerve branch. Then the treatment device is rotated by 180 degrees to target the posterior vagus nerve trunk, where the new position of the treatment device may be confirmed by xray, magnetic resonance imaging, or other known imaging techniques. Once the new position of the treatment device is confirmed as being appropriate, the ablation depth is adjusted with an imaging crystal along a radial line of the esophagus and high level energy is emitted from the treatment device to ablate and disrupt the posterior vagal nerve branch.  
         [0053]      FIG. 13A  is a diagrammatic illustration of an ultrasound transducer installed in the esophagus. As shown in this figure, the transducer device  16  is installed in the esophagus  1  in the region of the Z-line  4 . The subhiatal fat ring  20  is also shown. When the transducer  17  is activated, ablating energy will be radiated through the wall of the esophagus to ablate the vagal nerve branches  21  which are also shown diagrammatically.  
         [0054]     Although the esophagus is generally illustrated anatomically as a generally cylindrical tube, in its relaxed condition it assumes a more elliptical configuration which can be characterized as floppy. In other words, somewhat like a sock before it is put upon a foot, it does not assume a generally circular configuration unless it contains food or other object, but otherwise has a configuration in which the opposing walls of the esophagus are closer together than they would be when in a circular configuration. For example,  FIG. 13B  illustrates the stomach  3  and esophagus  1  when an elongate device  28  having a D-shaped distal tip  30  is in place in the esophagus  1 . The elongate device  28  is preferably thin, flexible and torqueable. The “D” shape of the distal tip  30  causes the esophagheal wall to take on a D shape, with a flat portion  31 , as further illustrated in the cross section illustration of  FIG. 13C .  FIG. 13C  illustrates a cross section of the esophagus  1  when the D-shaped distal tip  30  is in place. A HIFU transducer  32  is preferably inside the D-shaped distal tip. By positioning the HIFU transducer  32 , which is preferably directed to focus its energy at the flat portion  31  of the D, there is an ablation zone  36  that encompasses the anterior vagal nerve  34 . By rotating the D-shaped distal tip  30 , the ablation zone can include the posterior vagal nerve  38  or a vagal nerve branch. Thus, when the treatment device  50  is inserted into the esophagus, a cross section of the esophagus would preferably be D-shaped, where the focal point of the energy would be directed in the direction of the flat portion of the “D.” 
         [0055]     In  FIG. 14 , esophagus  1  with vagal nerve branches  8  on its outer wall is provided with a transducer  22  which has radially extending struts  23 . Each of these struts  23  has a rounded portion  24  at its distal end. The struts  23  and  24  serve to hold the esophagus in its relaxed generally elliptical shape and to hold the transducer  22  in the desired location as well. In an alternative embodiment illustrated in  FIGS. 15 and 16 , balloons  25  mounted on the side of the transducer-containing device  26  are implemented to hold the esophagus in a more ellipitical shape. When these types of devices are used, the transducer device  22  or  26  could be constructed to direct ultrasound energy towards the vagal nerve branches  8  in one direction or in two directions.  FIG. 15  shows the balloons  25  in the deflated state and  FIG. 16  shows the balloons in the inflated state.  
         [0056]     Ultrasound heating technology, including high-intensity ultrasound and HIFU are well understood. For example, Chapter 12, entitled “Ultrasound heating technology,” of “Thermo-radiotherapy and Thermo-chemotherapy,” vol. 1, edited by Seegenschmiedt, Fessenden and Vernon, contains a thorough explanation of the use of ultrasound in thermal therapy. This chapter is incorporated by reference herein. In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. For example, each feature of one embodiment can be mixed and matched with other features shown in other embodiments. As another example, the order of steps of method embodiments may be changed. Features and processes known to those of ordinary skill may similarly be incorporated as desired. Additionally and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted, but rather to be given the full scope of the attached claims and their equivalents.