Abstract:
The present invention provides an anastomosis device which includes an elongate center pin having proximal and distal ends. The proximal end is configured to be graspable using a grasping tool. A grip mechanism is located at the distal end for crimping a suture. The device includes an outer sleeve having a passageway therethrough to receive therein the elongate center pin. A suture having a suture needle is attached to a first end of the center pin and a second end of the suture is formed into a pre-formed knot mounted on the sleeve. The device includes a suture release mechanism having a passageway extending therethrough to receive the outer sleeve therein. The suture release mechanism slides along the sleeve between a first position in which the suture release mechanism is spaced from the distal end and a second position such that movement of the suture release mechanism from the first position to the second position dislodges the pre-formed knot off the sleeve. A free end of the suture, which was attached to a suture needle but cut lose after the suture has been passed through the tissue being sutured, is crimped by the crimp mechanism. The pre-formed knot is dislodged such that the crimped end of the suture is located within the pre-formed knot and pulling the suture through the knot tightens the pre-formed knot on the suture.

Description:
CROSS REFERENCE TO RELATED U.S PATENT APPLICATION 
       [0001]    This patent application relates to U.S. provisional patent application Ser. No. 61/353,993 filed on Jun. 11, 2010, entitled ANASTOMOSIS DEVICE AND METHOD OF USING THE SAME, filed in English, which is incorporated herein in its entirety by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a device for accomplishing the surgical process of anastomosis i.e. connecting two structures (commonly tubular structures) to restore continuity after resection or to bypass an unresectable disease process. More particularly the present invention relates to an anastomosis device for performing the process of connecting the structures in an end-to-end, side-to-side or an end-to-side fashion. 
       BACKGROUND OF THE INVENTION 
       [0003]    A common requirement in many surgical procedures is the resection or bypass of a diseased organ. Often the diseased section is a part of a tubular structure i.e. artery, bowel, esophagus and therefore after the resection it is required to reattach the resulting two healthy ends. This procedure is termed as anastomosis and is a fairly easy task to perform in the setting of an open surgery. However, in minimally invasive surgery where the procedure is performed through small incisions in the patient&#39;s skin, anastomosis is an extremely difficult skill to learn and execute. Typically, anastomosis time in a MIS procedure range between half an hour up to two hours. Needless to say, the long anastomosis time has a negative impact on the patient due to increased anesthesia requirement. For the surgeon, laparoscopic anastomosis is extremely difficult to learn and perform and is very fatiguing in nature. Increased anastomosis time is also a burden on the healthcare provider as it takes up valuable operating room time and adds to the personnel cost. 
         [0004]    U.S. Pat. No. 6,358,258 issued to Arcia et al. discloses an anastomosis device that utilizes multiple flexible needles (designed of Nitinol material) that are deployed through multiple curved guide channels. The design utilizes multiple push rods for actuation and is suitable for end-side type anastomosis. 
         [0005]    U.S. Pat. No. 7,029,481 issued to Burdulis et al. discloses an anastomosis device that utilizes multiple needles that are simultaneously is pierced through the tissue using a pneumatic cylinder. The needles latch onto small crimps on the opposite end and pull the sutures through the tissue upon retraction. The other end of the device utilizes multiple flexible needles deployed using curved channels and multiple push rods. The design needs custom needles as the sutures are attached to the distal tip of the needle as opposed to the proximal end found in conventional sutures. 
         [0006]    U.S. Patent Application US2008/0275472, to Yossepowitch et al. discloses an anastomosis device that utilizes multiple needle deployment through the use of flexible needle and curved guide channels. The design utilizes multiple push rods and requires custom needles to function. Even though the two ends of the design are attached through a flexible coupler, the design lacks a good suture management scheme and will suffer from suture tangling. Similar to U.S. Pat. No. 7,029,481, the design needs custom needles as the sutures are attached to the distal tip of the needle as opposed to the proximal end found in conventional sutures. 
         [0007]    Thus, there is a need for an automated/assisted laparoscopic anastomosis device that can reduce procedure time and operating costs. The device will also be of interest to the surgeons as it would minimize the dependence on a surgeon&#39;s dexterity and experience and will reduce the learning curve of this complex task. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides an anastomosis device, comprising: 
         [0009]    a) an elongate center pin having proximal and distal ends, said is proximal end structured to be manipulatable by a manipulation tool, a grip mechanism located at said distal end for gripping a suture; 
         [0010]    b) an outer sleeve having a passageway therethrough to receive therein the elongate center pin, said sleeve being mountable by a pre-formed knot formed in a suture; and 
         [0011]    c) a suture release mechanism having a passageway extending therethrough to receive the outer sleeve therein, said suture release mechanism being reciprocally translatable on said sleeve between a first position and a second position, and movement of said suture release mechanism from said first position to said second position dislodges said pre-formed knot off said sleeve, and with a free end of said suture being gripped by said grip mechanism, said pre-formed knot is dislodged such that said suture is located within said pre-formed knot and pulling said free end tightens said pre-formed knot on said suture. 
         [0012]    In another aspect of the present invention there is provided an anastomosis device, comprising: 
         [0013]    a) an elongate center pin having proximal and distal ends, said proximal end structured to be manipulatable by a manipulation tool; 
         [0014]    b) an outer sleeve having a passageway therethrough to receive therein the elongate center pin, said sleeve being mountable by a pre-formed knot formed in a suture; 
         [0015]    c) a suture release mechanism having a passageway extending therethrough to receive the outer sleeve therein, said suture release mechanism being reciprocally translatable on said sleeve between a first position and a second position, and movement of said suture release mechanism from said first position to said second position dislodges said pre-formed knot off said sleeve, and with a free end of said suture being gripped by said grip mechanism, said pre-formed knot is dislodged such that said suture is located within said pre-formed knot and pulling said free end tightens said pre-formed knot on said suture; and 
         [0016]    d) a grip mechanism located at said distal end for gripping a suture, the grip mechanism comprising a head section attached to the distal end of said elongate center pin, and a groove disposed on the head section comprising an elongate channel having a width and length and an opening thereto, wherein the opening has a width less than that of the elongate channel, thereby allowing a suture to be inserted into the channel through the opening and to remain firmly held in place in the channel. 
         [0017]    A further understanding of the functional and advantageous aspects of the invention can be realized by reference to the following detailed description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which: 
           [0019]      FIG. 1  shows an exemplary embodiment of two tubular structures after the anastomosis has been performed; 
           [0020]      FIG. 2  is a perspective view of an embodiment of an anastomosis device constructed in accordance with the present invention; 
           [0021]      FIG. 3  is a side view of the anastomosis device of  FIG. 2 ; 
           [0022]      FIG. 4  shows an exploded perspective view of the device of  FIG. 2 ; 
           [0023]      FIG. 5  shows a perspective view of a laparoscopic tool that combines grasping and cutting functionality into a single tool used with the anastomosis device; 
           [0024]      FIG. 6  shows a close up view of a portion of the grasping and cutting laparoscopic tool of  FIG. 5  used with the anastomosis device; 
           [0025]      FIG. 7  shows the close up view of a scissor actuation mechanism forming part of the grasping and cutting laparoscopic tool 
           [0026]      FIG. 8  shows the preferred embodiment of a laparoscopic tool  200  that combines grasping functionality with a sliding push-rod tool. 
           [0027]      FIG. 9  is a close-up view of the distal end of the combined grasper and push-rod tool according to the disclosed invention. 
           [0028]      FIG. 10  is a perspective view showing the anastomosis tool with a pre-formed knot; 
           [0029]      FIGS. 11 to 14  show various steps carried out by a surgeon using the present anastomosis tool to suturing, in which: 
           [0030]      FIG. 11  is a perspective view showing the needle and the suture after they have been manually passed through both sides of the target vessel by the anastomosis device; 
           [0031]      FIG. 12  is a perspective view showing the anastomosis device with a combined laparoscopic grasper and push-rod tool, with this configuration the surgeon wraps the trimmed end of the suture around a center pin head forming part of the anastomosis device preferably one or more revolutions; 
           [0032]      FIG. 13  is a perspective view showing the pre-formed knot after it has been released from the anastomosis device onto the trimmed end of the suture; 
           [0033]      FIG. 14  is a perspective view showing the target vessel after the knot shown released in  FIG. 13  has been tightened and trimmed; and 
           [0034]      FIG. 15  is a perspective view of a second embodiment in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Without limitation, the majority of the systems described herein are directed to an anastomosis device for performing the process of connecting the structures in an end-to-end, side-to-side or an end-to-side fashion, and method of using the same. As required, embodiments of the present invention are disclosed herein. However, the disclosed embodiments are merely exemplary, and it should be understood that the invention may be embodied in many various and alternative forms. 
         [0036]    The Figures are not to scale and some features may be exaggerated or minimized to show details of particular elements while related elements may have been eliminated to prevent obscuring novel aspects. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. For purposes of teaching and not limitation, the illustrated embodiments are directed to an anastomosis device for performing the process of connecting the structures in an end-to-end, side-to-side or an end-to-side fashion. 
         [0037]    As used herein, the term “about”, when used in conjunction with ranges of dimensions, temperatures or other physical properties or characteristics is meant to cover slight variations that may exist in the upper and lower limits of the ranges of dimensions so as to not exclude embodiments where on average most of the dimensions are satisfied but where statistically dimensions may exist outside this region. For example, in embodiments of the present invention dimensions of components of a laparoscopic anastomosis device are given but it will be understood that these are not meant to be limiting. 
         [0038]    As used herein, the process of “anastomosis” refers to the process of reattaching two healthy ends of an anatomical tubular structure (such as blood veins, arteries, intestines etc.) after a resection has been carried out to remove a diseased or injured section.  FIG. 1  shows an exemplary embodiment of two tubular structures after the anastomosis has been performed. 
         [0039]    As used herein, the phrase “anastomosis device” refers to a device for performing process of anastomosis which forms the subject matter of the present invention. 
         [0040]    The present invention discloses an anastomosis device that utilizes conventional sutures with a mechanism that holds a pre-formed knot to expedite the task of anastomosis. The workflow of the anastomosis device is similar to that of conventional suturing, however it facilitates easy anastomosis that is quick to perform and minimizes the dependence on a surgeon&#39;s dexterity. 
         [0041]      FIG. 2  shows an embodiment of the anastomosis device  10  comprising four main components: center pin  12 , outer sleeve  26 , suture release mechanism  30  and locking mechanism  40 . The center pin  12  includes a head  14  rigidly attached to it on the distal end through the use of a press fit pin  16 . The outer sleeve  26  and locking mechanism  40  are rigidly attached together and therefore act as a single entity in the mechanism. The proximal end of center pin  12  includes saw tooth profile  18  that includes one or more teeth and a proximal end  20  that can be grabbed using a grasper or a similar tool. The center pin  12  can be translated with respect to the outer sleeve  26  through the use of locking mechanism  40 . The locking mechanism  40  includes a saw-tooth profile  44  that mates with the saw-tooth profile  18  on the center pin  12 . The suture release mechanism  30  can be translated with respect to the locking mechanism  40  and is limited in its motion through the use of built in grooves  42  and a stop  34  in the locking mechanism  40 . 
         [0042]      FIG. 3  shows the side view of the embodiment of  FIG. 2 . Note that the saw-tooth profile  18  on the center pin is designed to mate with the saw-tooth profile  44  on the locking mechanism  40 . The locking mechanism  40  permits motion of the center pin  12  in the direction of arrow (as shown) and locks in the opposite direction. Since the device is a one-time use device there is no need to unlock it. At the end of its travel, the center pin  12  is butted against the outer sleeve  26  and is kept in tight contact due to the saw tooth profile  18 . In this position, the V-shaped profile on the center pin head  14  is in firm contact with the mating profile on the inside of the outer sleeve  26 . The functionality of this profile will be explained in detail later. 
         [0043]      FIG. 4  shows the exploded view of the same embodiment as that shown in  FIGS. 2-3 . As shown, the center pin includes two parts; center pin body  12  and center pin tip  14  for ease of assembly. The two parts are rigidly attached to each other through the use of a press fit steel pin  16  during assembly. 
         [0044]      FIG. 5  shows an embodiment of a laparoscopic tool  100  that combines grasping and cutting functionality into a single tool. The tool  100  includes a slender grasping/cutting end  102  that is inserted into the patient&#39;s body cavity and a proximal end  104  that includes two levers  110  and  112  for the grasping action and a cutting (scissor) actuation mechanism  124 . As with a conventional laparoscopic grasper, the opening and closing of the grasper levers  110  and  112  causes either one or both grasper tips  106  and  108  to open and close, respectively. The scissor actuation mechanism  124  is preferably utilized while the grasper tips  106  and  108  are in its closed position. The forward motion (towards the distal end) of the scissor actuation mechanism  124  causes the outer sleeve  120  of the instrument to move in a forward direction and vice versa. 
         [0045]      FIG. 6  shows the close up view of the embodiment of a combined grasping and cutting laparoscopic tool  100 . Utilizing this tool, the suture can be grasped using the graspers  106  and  108  in a conventional manner. The scissor actuation mechanism  124  can then be translated that will result in the translation of sleeve  120  and therefore scissor edge  122  along the grasper surface, resulting in cutting of the suture. 
         [0046]      FIG. 7  shows the close up view of the scissor actuation mechanism  124 . The forward (towards the distal end of the laparoscopic instrument) motion of the lever  124  causes the scissor tip  122  to translate forward against the grasper surface and results in cutting of the suture. 
         [0047]      FIG. 8  shows an embodiment of a laparoscopic tool  200  that combines grasping functionality with a sliding push-rod tool. The tool  200  includes a slender end  202  that is inserted into the patient&#39;s body cavity and a proximal end  204  that includes two levers  210  and  212  for grasping action and an actuation mechanism  224  for the push-rod. As with a conventional laparoscopic grasper, opening and closing of the grasper levers  210  and  212  causes one or both grasper tips  206  and  208  to open and close, respectively. The push-rod actuation mechanism  224  is utilized while the grasper tips  206  and  208  are in its closed position. The forward motion (towards the distal end) of the push-rod actuation mechanism  224  causes the outer sleeve  220  (and push-rod tip  222 ) of the instrument to move in a forward direction. The preferred method of use for this tool will be described in details later. 
         [0048]      FIG. 9  shows a close-up view of the distal end  202  of the combined grasper and push-rod tool  200 . 
         [0049]      FIG. 10  shows the anastomosis tool  10  with a suture  52  and a pre-formed knot  50  formed on the proximal end  52   b  of the suture. Knot  50  is preferably a type of slip knot that once slid on suture  52 , is prone to unwinding. It can be seen that the anastomosis device  10  is designed as a one-time-use disposable device and is supplied with the needle  54  and suture  52  with a pre-formed knot  50 . Various means can be provided on the device to ensure that knot does not accidently slip from the device during handling. One preferred method will be to provide a groove on the suture release mechanism  30  and the proximal end  52   b  of the suture  52  can be latched in this groove to avoid accidental slippage of the knot. The suture can then be removed from this groove by the surgeon using the laparoscopic grasper after the needle has been passed through both ends of the target anatomy and the anastomosis device is ready to be deployed. Other means of constraining the knot can be utilized without changing the scope of the invention. The preferred method of performing an anastomosis according to disclosed invention will now be described in detail. 
         [0050]    One method of performing anastomosis using the disclosed embodiments herein requires the use of two laparoscopic ports on the patient&#39;s body. A third laparoscopic port is utilized to obtain images of the target anatomy using an endoscope that is connected to an external monitor for visualization. As a first step, the surgeon introduces the anastomosis device  10  (including the suture  52  and needle  54 ) into the patient&#39;s body cavity through one of the ports. For this task, the surgeon can utilize a laparoscopic tool  100  or  200  to aid in easy insertion. As a next step, the surgeon introduces the combined laparoscopic grasping and cutting tool  100  ( FIG. 5 ) and the combined laparoscopic grasping and push-rod tool  200  ( FIG. 8 ) through the two ports into the patient&#39;s body cavity. In a manner similar to conventional anastomosis, the surgeon then utilizes both hands and left and right graspers  100  and  200  to pass the needle through two ends of the organs to be connected. 
         [0051]      FIG. 11  shows the needle and the suture after they have been manually passed through both sides of the target vessel  60 .  FIG. 11  also shows an exemplary opening  62  in vessel  60 . The objective of anastomosis is to approximate vessel  60  such that the two sides  64   a  and  64   b  of the opening  62  are in firm contact with each other and form a leak-proof seal after the anastomosis has been completed. After passing the needle through two sides  64   a  and  64   b , the surgeon utilizes the laparoscopic tools  100  and  200  and the scissor mechanism  122  (on the combined grasper and cutting tool  200 ) to cut needle  54  from the distal end  52   a  of suture  52 . Optionally, the surgeon can remove needle  54  from the body through one of the laparoscopic ports at this time. 
         [0052]    Referring now to  FIG. 12 , the next step requires the surgeon to grasp the disclosed anastomosis device  10  (from the proximal end  20 ) using the combined laparoscopic grasper and push-rod tool  200 . Using the other hand and the laparoscopic grasper/cutter  100 , the surgeon wraps the trimmed end of the suture  52  around the center pin head  14  preferably one or more revolution. With the wrapped suture in its place around the center pin head  14 , the surgeon actuates the push-rod mechanism  222  that grips the trimmed end of the suture between the center pin head  14  and the outer sleeve  26 . The locking action of the saw-tooth profile  18  and  44  on the center pin  12  and the locking mechanism  40  ensures that the suture  52  stays tightly gripped between the center pin head  14  and the outer sleeve  26 . With the center pin  12  firmly held by the laparoscopic grasper and push-rod tool  200 , the surgeon utilizes the other laparoscopic tool  100  to actuate the suture release mechanism  30  (by applying a sliding force towards the distal end of the disclosed anastomosis device  10 ). The suture release mechanism  30  can have notched profile on its surface to aid in application of the proper sliding force. This step essentially slides the pre-formed knot  50  from the outer sleeve  26  on to the trimmed section of the suture  52  (that has already been passed through the target vessel  60 ). 
         [0053]      FIG. 13  shows the pre-formed knot  50  after it has been released onto the trimmed end  52   a  of the suture  52 . The surgeon can now release the anastomosis device  10  from the laparoscopic grasper/push-rod tool  200 . The surgeon can then utilize both graspers  100  and  200  to tighten the knot  50  on the trimmed section  52   a  of the suture. The diameter of the outer sleeve  26  is preferably twice the diameter of the suture  52  and therefore knot  50  is fairly well formed as it is released from the outer sleeve  26 . From this point onwards, the surgeon can utilize one grasper (for example  200 ) to hold the trimmed end  52   a  of the suture  52  and the other grasper  100  to slide the knot  50  towards the target vessel  60  to tighten the knot and complete the anastomosis. Once the wound closure is tight enough (as judged by the surgeon), the surgeon can utilize the cutting tool  122  to trim the suture  52  to the desired length and remove the disclosed anastomosis device  10  (which is also holding the remaining suture  52  gripped on the center pin  12 ) from the patient&#39;s body. Optionally, the surgeon may remove needle  54  from the body through one of the laparoscopic ports at this time. 
         [0054]      FIG. 14  shows the target vessel  60  after the knot  50  has been tightened and trimmed. These steps are repeated with a new anastomosis device  10  introduced each time and a new knot  50  being applied until a proper anastomosis of the anatomy is achieved. A typical end-to-end anastomosis could require 6 to 8 sutures for proper approximation of the anatomy. In embodiments herein, the task of releasing pre-formed knot from the outer sleeve requires the surgeon to use both hands. However, this task can also be completed with one hand through redesign of the laparoscopic grasper/push-rod  200  through inclusion of another concentric shaft to actuate suture release mechanism  30  without changing the scope of the invention. In addition to the knot  50  shown in the disclosed invention, other forms of knots can be utilized without changing the scope of the invention. 
         [0055]      FIG. 15  is a perspective view of a further embodiment of the anastomosis device  300 .  FIG. 15  shows this embodiment, which includes two components  302  (composed of profiles  302   a - 302   f  and  314 ) and  304 . Profile  302   a  on the distal end is designed to host a pre-formed knot  50  (similar to  FIG. 10 ), profile  302   c  includes two guiding grooves  314  and profile  302   d  is the flatted proximal end that can be held utilizing tool  200  ( FIG. 8 ). The distal end also includes a profile  302   b  (preferably cylindrical) that consists of an opening  302   e  and a gripping mechanism with a groove  302   f . This gripping mechanism is designed to allow a suture to be lockably placed therein. Component  304  includes two substantially narrow profiles  306 , and two end-stops  308 . Each of the end-stops  308  is designed to slidably fit inside the corresponding guiding groove  314  and can translate linearly with component  304 . 
         [0056]    It can be seen that device  300  has substantially simplified design as compared to device  10  ( FIG. 2 ) at the same time exhibiting similar functionality. The functioning of device  300  will now be described in detail. Similar to device  10 , device  300  is also packaged as one-time use disposable with the suture  52  and is introduced into the patient&#39;s body cavity in a similar fashion. Once the distal end  52   a  of the suture (containing needle  54 ) has been passed through two ends of the anatomy, the needle  54  is trimmed using the laparoscopic tool  100 . The surgeon then utilizes tool  200  and firmly holds device  300  at profile  302   d  using graspers  206  and  208 . Once the device is firmly held, the surgeon utilizes tool  100  to hold free end  52   a  of suture  52  and inserts it into the gripping mechanism groove  302   f . The insertion of suture  52  into groove  302   f  is assisted by the chamfered profile  302   e . The gripping mechanism groove  302   f  is dimensioned to lockably contain the suture once it is positioned inside the groove. The surgeon then actuates push-rod  220  on tool  200  that causes push-rod tip  222  to linearly translate and come in contact with surface  310  (on end-stop  308 ). As the push-rod is actuated further, a distal acting force on surface  310  causes component  304  to translated with respect to component  302  and causes preformed knot  50  to slide off profile  302   a . The surgeon then releases the grasper from proximal end  302   d  and utilizes graspers on tools  100  and  200  to tighten the knot. The process is repeated for each anastomosis device  300  until a proper anastomosis is accomplished. It can be noted that various profiles and sizes for gripping mechanism groove  302   f  can be utilized without changing the scope of the invention. 
         [0057]    The disclosed embodiments herein utilize a novel mechanical device that holds a pre-formed knot for easy and quick anastomosis. The embodiments disclosed herein minimize the dependence on a surgeon&#39;s dexterity and experience in performing the anastomosis. Thus, novice surgeons will be able learn and produce quality laparoscopic anastomosis in a short time using the disclosed invention. 
         [0058]    The system design is simple and therefore it can be mass produced at low cost using existing fabrication techniques. 
         [0059]    The design utilizes conventional needles and sutures and therefore does not require custom materials as needed in some prior art. 
         [0060]    Manual suturing is still the most widely accepted method of conducting anastomosis, and the similar workflow of the disclosed embodiments will be easily adapted to by surgeons. 
         [0061]    Further, the disclosed embodiments have a good market potential that is evident from the fact that even after centuries of technological development, only a handful of automated/assisted anastomosis devices exist in the market. Most of these devices are designed for open surgery and find little or no use in a minimally invasive surgery (MIS) approach. MIS has already become a preferred surgical approach due to its benefits to the patient and it is evident that the number of procedures performed through this approach will increase exponentially in the coming years. At the same time, without any improvement to the laparoscopic anastomosis technique, present anastomosis times of the order of hours will have a huge social and financial burden. Thus an anastomosis device that can potentially reduce anastomosis time from hours to minutes has high market value. 
         [0062]    The disclosed embodiments have advantages over existing devices and technologies in terms of their simplicity, close resemblance to manual suturing and low cost. Most of the existing technologies utilize custom designed needles/sutures whereas the disclosed embodiments utilize standardized off-the-shelf needle and sutures. In addition, the mechanical components of the disclosed embodiments can be constructed using materials such as plastics and can be produced at a low cost using standardized manufacturing process (injection molding etc.). The disclosed embodiments are suitable for all types of anastomosis (end-end, end-side and side-side) for vessels with varying diameters. 
         [0063]    As used herein, the terms “comprises”, “comprising”, “includes” and “including” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in this specification including claims, the terms “comprises”, “comprising”, “includes” and “including” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components. 
         [0064]    The foregoing description of the preferred embodiments of the invention has been presented to illustrate the principles of the invention and not to limit the invention to the particular embodiment illustrated. It is intended that the scope of the invention be defined by all of the embodiments encompassed within the following claims and their to equivalents.