Patent Publication Number: US-11648003-B2

Title: Biological tissue access and closure apparatus, systems and methods

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 16/418,463, filed on May 21, 2019, which is a continuation-in-part of U.S. application Ser. No. 15/991,441, now U.S. Pat. No. 10,702,263, filed on May 29, 2018, which claims the benefit of U.S. Provisional Application No. 62/512,180, filed on May 30, 2017, U.S. Provisional Application No. 62/618,634, filed on Jan. 18, 2018, and U.S. Provisional Application No. 62/655,151, filed on Apr. 9, 2018. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to apparatus, systems and methods for accessing internal structures and closing biological tissue. More particularly, the present invention relates to apparatus, systems and methods for accessing internal structures; particularly, intra-abdominal structures, and approximation, ligation, fixation and closure of openings in biological tissue; particularly, laparoscopic ports or incisions in biological tissue. 
     BACKGROUND OF THE INVENTION 
     As reported in a Jan. 31, 2017 iData Research press release, approximately 3.5 million laparoscopic surgical procedures are performed each year in the U.S and more than 7.5 million worldwide. The most common laparoscopic surgical procedures include a cholecystectomy, appendectomy, gastric bypass, nephrectomy and hernia repair. 
     As illustrated in  FIG.  1   , a laparoscopic surgical procedure generally comprises insertion of a trocar/cannula system  10 , such as shown in  FIGS.  2 - 4   , through layers of body tissue, such as the tissue  16  of an abdominal wall  12 , to a desired position proximate an internal organ of interest, such as the gallbladder. 
     As illustrated in  FIG.  2 - 4   , the conventional trocar/cannula system  10  comprises two seminal components: (i) a central obturator  20 , which comprises a handle  22 , shaft  23  and a puncturing tip  24 , and a cannula port  26 . The puncturing tip  24  is configured pierce through tissue and provide an incision for insertion of the cannula port  26 . As discussed below, the cannula port  26  is configured to receive surgical instruments, e.g., endoscopes, and the like, therein, and, hence, facilitate surgical procedures to be performed inside a body cavity, such as an abdomen cavity  14 . 
     After the puncturing tip  24  and, hence, obturator  20  are disposed in a desired position within the body cavity, the obturator  20  is removed from the cannula port  26 . The cannula port  26  then provides an access or working portal through the tissue for surgical instruments to perform a desired surgical procedure inside the body cavity, e.g., a gastric bypass. 
     As is well known in the art, numerous laparoscopy methods currently exist for performing laparoscopic surgical procedures. One of the more commonly used laparoscopy methods is known as closed laparoscopy. Referring back to  FIG.  1   , closed laparoscopy employs a sharp needle (e.g., Veress™ needle) to pierce through tissue, such as abdominal wall tissue  16 , and insufflate the body cavity, e.g., abdominal cavity  14 , with an inert gas, such as carbon dioxide (CO 2 ). The process of insufflating the body cavity separates the cavity tissue and associated structure, e.g., abdominal wall  12 , from the underlying organ(s), thus, creating a space or gap  18  for a surgeon to work within. A trocar/cannula system is then employed to maintain the insufflated space or cavity  18  and provide a working portal through which surgical instruments can be passed into and out of the insufflated cavity  18  to perform a desired surgical procedure. 
     As is also well known in the art, one of the most common post-operative complication associated with a laparoscopic surgical procedure is the incidence of trocar-site hernias, where a portion of an organ or fatty tissue protrudes through the opening in the tissue created by a trocar access portal. It is believed that inadequate closure of the trocar access portal is the primary cause of trocar-site hernias. 
     Various methods for closing a trocar access portal have thus been developed and employed. Although the noted methods can, in most instances, be employed to successfully close a trocar access portal, there are several significant drawbacks and disadvantages associated with the methods. Indeed, as discussed below, most, if not all, current trocar access portal closing methods are typically difficult to perform, require considerable time to execute and do not provide for a simple, reproducible and reliable means of closing the trocar access portal. Illustrative are the trocar access portal closing methods disclosed in U.S. Pat. Nos. 919,138, 3,946,740, 4,621,640, 8,109,943, and Pub. No. 2016/0228107. 
     U.S. Pat. Nos. 919,138, 3,946,740 and 4,621,640 disclose similar conventional methods for closing trocar access portals that comprise guiding a suture engaged to a needle through the trasversalis fascia with needle-nosed forceps or other specialized apparatus. A major drawback and disadvantage associated with the disclosed methods is that the apparatus and methods are primarily dependent on the dexterity of the surgeon operating the apparatus and executing the associated methods. 
     A further disadvantage associated with the methods disclosed in U.S. Pat. Nos. 919,138, 3,946,740 and 4,621,640 is that the surgeon operating the apparatus associated with the methods must either perform the trocar access portal closure “blind”, i.e., without visual access to interior body tissues, e.g., intra-abdominal fascia, or with the assistance of an endoscope inserted into the body cavity from an additional access portal. 
     A further disadvantage is that an exposed needle must be handled by a surgeon inside of a body cavity with limited visual access, thus, which increases the risk of injury to the local structures inside of a patient, e.g., organs. 
     A further disadvantage associated with the apparatus and methods disclosed in U.S. Pat. No. 919,138, 3,946,740 and 4,621,640 is that, if the surgeon desires to place more than one suture throw through the tissue, the surgeon must reload the needle into a needle driver apparatus. This can be done extracorporeally, i.e., outside the body, in a manner similar to the initial loading of the suture device, or it can be done intracorporeally, i.e., inside the body. This process is time consuming and oftentimes a frustrating exercise in hand-to-eye coordination. The apparatus and methods are thus configured and, hence, primarily employed for use in open surgical procedures where there is room for the surgeon to manipulate the instrument(s). 
     Another drawback associated with the apparatus and associated methods disclosed in U.S. Pat. Nos. 919,138, 3,946,740 and 4,621,640 is that the apparatus can, and often times will, fail to effectively close tissue that is disposed proximate the trocar access portal, which greatly increases the patients risk of trocar-site herniation at the closure site. The seminal complications associated with trocar-site herniation include organ necrosis and closed loop intestinal obstruction, which can be life-threating. 
     A further drawback is that patients with relatively thick body tissues increase the difficulty, time and risk of trocar access portal closure complications, such as a misplaced suture and/or penetration of a patient&#39;s organs with the suture needle. 
     U.S. Pat. No. 8,109,943 and Pub. No. 2016/0228107 disclose further apparatus and methods for closing trocar access portals. The disclosed apparatus generally comprises a trocar device that is loaded with operator actuated injectors. The injectors are configured and positioned to insert suture anchors with sutures attached thereto into the tissue of a patient, such as an abdominal wall. 
     A major drawback and disadvantage associated with the methods disclosed in U.S. Pat. No. 8,109,943 and Pub. No. 2016/0228107 is that the stitch produced does not encompass the anterior fascia and peritoneum and, hence, does not fully close the defect in a traditional manner. The efficacy of closing only the anterior fascia is often questioned by surgeons. 
     Further, the surgeon operating the trocar must again either perform the trocar access portal closure “blind”, i.e., with limited visual access to interior body tissues, or with the assistance of an endoscope inserted into the body cavity from an additional access portal. 
     A further drawback associated with the methods disclosed in U.S. Pat. No. 8,109,943 and Pub. No. 2016/0228107 is that, even if the trocar device is appropriately positioned in a patient, there is no means to ensure that the anchors will completely penetrate the targeted body tissues and successfully close the trocar access portal. 
     A further drawback is that at least two (2) exposed suture needles must be handled by a surgeon inside of a patient&#39;s body cavity with limited visual aid, which, as indicated above, greatly increases the risk of injury to the local structures, e.g., organs. 
     Another drawback associated with the apparatus and methods disclosed in U.S. Pat. No. 8,109,943 and Pub. No. 2016/0228107 is that the suture anchors are formed from polymeric and/or metallic materials, i.e., non-endogenous material structures, which, after the laparoscopic procedure, remain anchored in the body tissue of the patient. The suture anchors thus can, and often times will, elicit an adverse inflammatory response in the patient. There is also a substantial risk of dislodgment of the suture anchors from body tissue, which can also cause serious postoperative complications. 
     A further method for closing a trocar access portal comprises use of a trocar device manufactured and distributed by Medtronic® under the tradename VersaOne™ All-in-One (AIO) trocar and closure device. 
     The Medtronic® device, which is illustrated in  FIGS.  2 - 4   , employs a guide component that is configured to be positioned in the trocar cannula. The guide component includes two (2) diagonally oriented channels that are configured to guide a suture through two (2) contra-laterally opposed regions of body tissue, e.g., intra-abdominal fascia. The suture is guided through the two (2) contra-laterally opposed regions of body tissue using a specialized grasper needle that can traverse the diagonally oriented channels and a secondary grasper tool controlled from an additional trocar access portal that is disposed proximate the trocar device. 
     Several drawbacks and disadvantages are similarly associated with the Medtronic® device and associated method. A major drawback and disadvantage is that there is no reliable means associated with the Medtronic® device for a surgeon to assess whether the device is properly positioned in (or through) the body tissue of a patient. The device merely employs fixed circumferential bands on the device housing to indicate and, hence, ensure desired tissue approximation positioning. It is, however, very difficult, if not impossible to achieve proper trocar device positioning for every patient via the fixed circumferential bands due to varying body tissue thicknesses encountered from patient-to-patient. As a result of inaccurate positioning of the Medtronic® device, the associated method can cause unintended damage or trauma to local tissues. The Medtronic® method can also fail to successfully close a trocar access portal, which can lead to the above noted complications, e.g., trocar-site herniation. 
     A further drawback associated with the Medtronic® method is that the method requires a secondary grasper tool controlled from an additional trocar access portal in order to guide a suture through the two (2) contra-laterally opposed regions of body tissue. A surgeon is thus required to induce further tissue trauma by deploying a second trocar in a patient&#39;s body tissue to generate an additional trocar access portal for the grasper tool. 
     A further drawback associated with the Medtronic® method is that it is extremely difficult and cumbersome to manipulate and engage the intra-cavity suture with the grasper tool. 
     Another drawback associated with the Medtronic® method is that the method also requires that at least one (1) sharp instrument be introduced to and manipulated within a body cavity with limited visual access to interior body tissues, which as indicated above, substantially increases the risk of injury to the local structures inside of a patient, e.g., organs. 
     It is thus desirable to provide an improved tissue closure system and method that substantially reduces or eliminates the disadvantages and drawbacks associated with conventional, known tissue closure and associated methods. 
     It is therefore an object of the present invention to provide tissue closure systems and associated methods that substantially reduce or eliminate the disadvantages and drawbacks associated with conventional, known tissue closure apparatus and associated methods. 
     It is a further object of the present invention to provide tissue access and closure systems that can be readily employed to facilitate various laparoscopic surgical procedures in a simple and economical manner. 
     It is a further object of the present invention to provide tissue access and closure systems that can be readily employed to access internal structures; particularly, intra-abdominal structures in a minimally invasive manner. 
     It is a further object of the present invention to provide tissue access and closure systems that can be readily employed to effectively approximate, ligate, fixate and close biological tissue; particularly, laparoscopic ports or incisions in biological tissue. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to apparatus, systems and methods that are configured to (i) pierce through tissue and provide access to internal structures; particularly, intra-abdominal structures, and (ii) close openings in biological tissue, more preferably, approximate and/or ligate and/or fixate and close openings in biological tissue; particularly, laparoscopic ports or incisions in biological tissue. 
     In one embodiment of the invention there is thus provided a method for closing an opening in biological tissue, comprising the steps of:
         (i) providing a tissue closure system comprising a suture guide sub-system and suture passer sub-system, the suture guide sub-system comprising an elongated housing comprising a distal region and an open internal region disposed in the distal region, the distal region being configured to transition into and through a tissue structure,   the suture guide sub-system housing further comprising a suture passer lumen that is sized and configured to receive the suture passer sub-system therein and an open tissue positioning region proximate a distal region of the suture guide sub-system housing that is adapted to receive tissue therein,   the suture guide sub-system housing further comprising adjustable tissue capture means disposed proximate the open tissue positioning region that is configured and positioned to linearly translate from a first guide shaft position to a second guide shaft position, wherein the adjustable tissue capture means is capable of engaging tissue disposed in the open tissue positioning region,   the distal region of the suture guide sub-system housing further comprising suture engagement means comprising a suture capture door that is configured to obstruct passage of the suture passer sub-system through the suture guide sub-system housing when in a closed position,   the suture capture door is further configured to transition from the closed position to an open position, wherein passage of the suture passer sub-system through the suture guide sub-system housing is allowed,   the suture capture door is further configured to engage and retain a suture that is releasably secured to the suture passer sub-system when the suture passer sub-system and engaged suture are inserted through and subsequently withdrawn from the suture capture door,   the suture passer sub-system comprising an actuator, a suture passer cannula and a suture deployment shaft, the suture passer cannula being configured to slidably receive the suture deployment shaft therein,   the suture deployment shaft comprising suture deployment and capture means for delivering a suture to biological tissue and capturing and releasably securing the suture therewith;   (ii) inserting the suture guide sub-system into and through a tissue opening in a biological tissue structure;   (iii) positioning the open tissue positioning region of the suture guide sub-system proximate a first tissue region of the biological structure, wherein the first tissue region is disposed in the open tissue positioning region of the suture guide sub-system;   (iv) engaging a first section of a suture with the suture passer sub-system;   (v) inserting the suture passer sub-system and the engaged first section of the suture into the suture guide sub-system, wherein the suture passer cannula is disposed proximate the first tissue region of the biological structure;   (vi) inserting the suture passer cannula of the suture passer sub-system and the engaged first section of the suture into and through the first tissue region of the biological structure and through the suture capture door of the suture guide sub-system;   (vii) withdrawing the suture passer cannula through the suture capture door and out of the first tissue region of the biological structure, wherein the first section of the suture is ensnared by the suture capture door and routed through the first tissue region of the biological structure;   (viii) withdrawing the suture passer sub-system out of the suture guide sub-system;   (ix) rotating the suture guide sub-system circumferentially, wherein a contralateral second tissue region of the biological structure is disposed in the open tissue positioning region of the suture guide sub-system;   (x) engaging a second section of the suture with the suture passer sub-system;   (xi) inserting the suture passer sub-system and engaged second section of the suture into and through the second tissue region of the biological structure and through the suture capture door of the suture guide sub-system;   (xii) withdrawing the first suture passer cannula through the suture capture door and out of the second tissue region of the biological structure, wherein the second section of the suture is ensnared by the suture capture door and routed through the second tissue region of the biological structure;   (xiii) withdrawing the suture passer sub-system out of the suture guide sub-system;   (xiv) withdrawing the suture guide sub-system from the first biological structure;   (xv) releasing the first and second sections of the suture that is ensnared by the suture capture door; and   (xvi) drawing the first and second sections of the suture together, wherein first and second tissue regions of the biological structure are drawn together and, thereby, the tissue opening in the biological tissue structure is closed.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages will become apparent from the following and ma particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings, and in which like referenced characters generally refer to the same parts or elements throughout the views, and in which: 
         FIG.  1    is an illustration of a prior art laparoscopic surgical procedure employing a conventional trocar apparatus; 
         FIG.  2    is a front plan view of a prior art cannula port; 
         FIG.  3    is a front plan view of a prior art obturator that is configured to cooperate with the cannula port shown in  FIG.  2   ; 
         FIG.  4    is a front plan view of a prior art trocar assembly comprising the cannula port and obturator shown in  FIGS.  2  and  3   ; 
         FIG.  5    is an exploded view of one embodiment of a tissue access and closure system, illustrating a cannula, suture guide and suture passer sub-system thereof according to the invention; 
         FIG.  6    is a front plan view of one embodiment of cannula sub-system, according to the invention; 
         FIG.  7 A  is a front plan view of one embodiment of a suture guide sub-system with a cooperating suture passer sub-system, according to the invention; 
         FIG.  7 B  is a perspective view of one embodiment of adjustable tissue capture means, according to the invention; 
         FIGS.  7 C and  7 D  are front plan views of the suture guide sub-system shown in  FIG.  7 A , employing the adjustable tissue capture means shown in  FIG.  7 B , according to the invention; 
         FIG.  7 E  is a front sectional view of another embodiment of adjustable tissue capture means, according to the invention; 
         FIG.  7 F  is a partial perspective view of the adjustable tissue capture means shown in  FIG.  7 E , according to the invention; 
         FIGS.  70  and  7 H  are front plan views of the suture guide sub-system shown in  FIG.  7 A , employing the adjustable tissue capture means shown in  FIGS.  7 E and  7 F , according to the invention; 
         FIGS.  5 A- 5 C  are partial perspective views of the suture guide sub-system shown in  FIG.  7 A , illustrating one embodiment of a tissue positioning sub-system, according to the invention; 
         FIG.  9    is a perspective view of another embodiment of suture guide sub-system with a cooperating suture passer sub-system, according to the invention; 
         FIG.  10    is a partial perspective view of the suture guide sub-system shown in  FIG.  9   , illustrating another embodiment of a tissue positioning sub-system, according to the invention; 
         FIG.  11    is a partial perspective, sectional view of the suture guide sub-system shown in  FIG.  9   , illustrating one embodiment of a continuous internal lumen therein, according to the invention; 
         FIGS.  12 A and  12 B  are partial perspective views of the suture guide sub-system shown in  FIG.  9   , illustrating the suture capture clip of the suture capture door system of the suture guide sub-system that is shown in  FIG.  10   , according to the invention; 
         FIG.  13    is a perspective view of one embodiment of a suture capture clip that is configured to cooperate with the suture capture door system shown in  FIGS.  12 A and  12 B , according to the invention; 
         FIG.  14    is a perspective view of one embodiment of a suture passer sub-system, according to the invention; 
         FIG.  15    is a partial front plan view of the suture passer sub-system shown in  FIG.  14   , illustrating the housing thereof, according to the invention; 
         FIG.  16    is a partial front plan sectional view of the suture passer sub-system shown in  FIG.  14   , according to the invention; 
         FIG.  17 A  is a partial perspective view of one embodiment of a suture passer sub-system cannula shaft, according to the invention; 
         FIGS.  17 B and  17 C  are partial perspective views of another embodiment of a suture passer sub-system cannula shaft, according to the invention; 
         FIG.  18    is a partial perspective view of the cannula shaft shown in  FIG.  17 A , illustrating one embodiment of suture capture means, i.e., a tong member, extended out of the cannula shaft in an extended state, according to the invention; 
         FIGS.  19 A- 19 C  are perspective views of the cannula shaft shown in  FIGS.  17 A and  18   , illustrating a suture connected to the suture capture means and the suture capture means in several stages of retraction in the cannula shaft, according to the invention; 
         FIG.  19 D  is a further perspective view of the cannula shaft shown in  FIGS.  17 A and  18   , illustrating the release of the suture from the suture capture means when the suture capture means is in a fully retracted state in the cannula shaft, according to the invention; 
         FIGS.  20 A and  20 B  are perspective views of the cannula shaft shown in  FIGS.  17 B and  17 C , illustrating the release of a suture from the suture capture means when the suture capture means is in a fully retracted state in the cannula shaft, according to the invention; 
         FIG.  21    is a flow chart, illustrating one embodiment of a method for accessing biological tissue and closing an opening in the tissue, according to the invention; 
         FIG.  22    is a front plan view of the assembled cannula and suture guide sub-systems shown in  FIGS.  5 , 6  and  7   , according to the invention; 
         FIGS.  23 A and  23 B  are front plan views of the assembled cannula, suture guide and suture passer sub-systems shown in  FIGS.  5 , 6  and  7   , illustrating the engagement of biological tissue with a tissue positioning sub-system, according to the invention; 
         FIG.  24    is a front plan view of the assembled cannula and suture guide sub-systems shown in  FIGS.  5 , 6  and  7    withdrawn from biological tissue, illustrating the placement of a suture by a suture passer sub-system, according to the invention; 
         FIG.  25    is a perspective view of one embodiment of a tissue closure system, according to the invention; 
         FIG.  26    is an exploded perspective view of the tissue closure system shown in  FIG.  25   , according to the invention; 
         FIG.  27    is a flow chart, illustrating one embodiment of a method for closing an opening in biological tissue using the tissue closure system shown in  FIG.  25   , according to the invention; 
         FIG.  28    is a partial perspective view of cannula shafts of the tissue closure system shown in  FIG.  25    with ends of a suture operatively connected thereto, according to the invention; 
         FIG.  29 A  is a partial perspective view of the tissue closure system shown in  FIG.  25    with an actuator in a fully retracted position, according to the invention; 
         FIG.  29 B  is another partial perspective view of the tissue closure system shown in  FIG.  25    with the actuator shown in  FIG.  29 A  in an advanced position, according to the invention; 
         FIG.  29 C  is another partial perspective view of the tissue closure system shown in  FIG.  25    with the actuator shown in  FIG.  29 A  in a partially retracted position, according to the invention; 
         FIG.  30 A  is another partial perspective view of the tissue closure system shown in  FIG.  25    with the actuator shown in  FIG.  29 A  engaged to a suture snare member, according to the invention; 
         FIG.  30 B  is another partial perspective view of the tissue closure system shown in  FIG.  25   , illustrating the position of the cannula shaft in the tissue positioning region, when the actuator shown in  FIG.  29 A  is in an advanced position, according to the invention; and 
         FIGS.  31 A and  31 B  are front plan views of the tissue closure system shown in  FIG.  25    positioned in a biological tissue structure, according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified apparatus, systems, structures or methods as such may, of course, vary. Thus, although a number of apparatus, systems and methods similar or equivalent to those described herein can be used in the practice of the present invention, the preferred apparatus, systems, structures and methods are described herein. 
     It is also to be understood that, although the present invention is described and illustrated in connection with laparoscopic procedures, the invention is not limited to such procedures. According to the invention, the apparatus, systems and methods of the invention can also be employed in connection with a multitude of other surgical procedures, including, without limitation, patent foramen ovale (PFO) closure, left ventricular closure and vascular, i.e., artery and vein, closure. 
     It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the invention pertains. 
     Further, all publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety. 
     As used in this specification and the appended claims, the singular forms “a, “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “an incision” includes two or more incisions and the like. 
     Further, ranges can be expressed herein as from “about” or “approximately” one particular value, and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about” or “approximately”, it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. 
     It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” or “approximately” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “approximately 10” is also disclosed. It is also understood that when a value is disclosed that “less than or equal to” the value, “greater than or equal to the value” and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value “10” is disclosed then “less than or equal to 10” as well as “greater than or equal to 10” is also disclosed. 
     DEFINITIONS 
     The terms “tissue” and “biological tissue” are used interchangeably herein, and mean and include mammalian biological tissue, such as, by way of example, human abdominal tissue. 
     The term “biological cavity”, as used herein, means and includes any cavity or space in a mammalian tissue structure. 
     The terms “patient” and “subject” are used interchangeably herein, and mean and include warm blooded mammals, humans and primates; avians; domestic household or farm animals, such as cats, dogs, sheep, goats, cattle, horses and pigs; laboratory animals, such as mice, rats and guinea pigs; fish; reptiles; zoo and wild animals; and the like. 
     The terms “one configuration,” “one embodiment,” “one aspect,” and “a configuration,” “an embodiment” and “an aspect,” as used herein, means that a particular feature, structure, or characteristic described in connection with the configuration may be included in at least one configuration and not that any particular configuration is required to have a particular feature, structure or characteristic described herein unless set forth in the claim. 
     The phrase “in one configuration” or similar phrases employed herein do not necessarily refer to the same configuration and, unless specifically stated, do not limit the inclusion of a particular element of the invention to a single configuration. The element may thus be included in other or all configurations discussed herein. 
     The term “substantially”, as used herein, means and includes the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result to function as indicated. For example, an object that is “substantially” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context, such that enclosing nearly all of the length of a lumen would be substantially enclosed, even if the distal end of the structure enclosing the lumen had a slit or channel formed along a portion thereof. 
     Use of the term “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, structure which is “substantially free of” a bottom would either completely lack a bottom or so nearly completely lack a bottom that the effect would be effectively the same as if it completely lacked a bottom. 
     The term “comprise” and variations of the term, such as “comprising” and “comprises,” means “including, but not limited to” and is not intended to exclude, for example, other components, elements or steps. 
     The following disclosure is provided to further explain in an enabling fashion the best modes of performing one or more embodiments of the present invention. The disclosure is further offered to enhance the understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the invention. The invention is defined solely by the appended claims, including any amendments made during the pendency of this application, and all equivalents of those claims as issued. 
     As indicated above, the present disclosure is directed to tissue access and closure apparatus, systems and methods for accessing internal structures; particularly, intra-abdominal structures, and closing openings in biological tissue; particularly, laparoscopic ports or incisions in biological tissue. 
     In a preferred embodiment of the invention, the tissue access and closure (“TAC”) systems are configured to (i) pierce through biological tissue and provide access to internal structures; particularly, intra-abdominal structures, and (ii) close openings in biological tissue, more preferably, approximate and/or ligate and/or fixate and close openings in biological tissue; particularly, laparoscopic ports or incisions in biological tissue. 
     As discussed in detail below, in a preferred embodiment of the invention, the TAC systems of the invention comprise the following sub-systems: (i) a cannula sub-system, (ii) suture guide sub-system, (ii) tissue positioning sub-system, and (iv) suture passer sub-system. 
     Referring now to  FIG.  5   , there is shown an exploded view of one embodiment of a TAC system (denoted “ 100 ”) of the invention comprising a cannula sub-system  200 , suture guide sub-system  300 , tissue positioning subsystem  400 , and suture passer sub-system  500 . 
     Referring now to  FIGS.  6 - 20   , each of the noted sub-systems will now be described in detail. 
     Cannula Sub-System 
     Referring first to  FIG.  6   , there is shown one embodiment of a cannula sub-system  200   a  of the invention. As illustrated in  FIG.  6   , the cannula sub-system  200   a  comprises a cannula base member  202 , comprising proximal and distal ends  212 ,  214 , and a cannula shaft  204 , which also comprises proximal and distal ends  216 ,  218 . In a preferred embodiment, the cannula shaft proximal end  216  is in direct communication with, i.e., secured to, the base member distal end  214 . 
     As further illustrated in  FIG.  6   , the cannula base member  202  includes a first cannula lumen  208   a , which extends from the proximal end  212  to the distal end  214  of the base member  202 , and the cannula shaft  204  includes a second cannula lumen  208   b , which extends from the proximal end  216  to the distal end  218  of the cannula shaft  204 . 
     In a preferred embodiment of the invention, the first and second cannula lumens  208   a ,  208   b  comprise the same diameter and are in an aligned relationship (forming a continuous, preferably, unobstructed cannula lumen  208   c ) when the cannula base member  202  is engaged to the cannula shaft  204 , i.e., the cannula shaft proximal end  216  is in direct communication with, i.e., secured to, the base member distal end  214 . 
     As discussed in detail below, the first and second cannula lumens  208   a ,  208   b  and, hence, continuous cannula lumen  208  are sized and configured to receive a suture guide sub-system  300  of the invention therein. According to the invention, the continuous cannula lumen  208   c  also defines an access port for surgical instruments that facilitates entry thereof into a body cavity when the cannula sub-system  200  is positioned therein. 
     In a preferred embodiment of the invention, the diameter of the first and second cannula lumens  208   a ,  208   b  and, hence, continuous cannula lumen  208   c  is in the range of 8-20 mm. 
     According to the invention, the cannula shaft distal end  210  can comprise various configurations, including, but not limited to, a beveled, curved and serrated edge, which is configured to pierce through biological tissue. 
     As illustrated in  FIG.  6   , in a preferred embodiment, the cannula shaft distal end  210  comprises a beveled edge having an angle “a” in the range of approximately 1-90° with respect to the longitudinal axis  215  of the cannula shaft  204 . More preferably, the angle “d” of the beveled cannula end  210  is in the range of approximately 45°-90°. 
     According to the invention, the cannula shaft  204  can also comprise various conventional materials, including, but not limited to, metal and polymeric materials. Thus, in some embodiments, the cannula shaft  204  comprises stainless steel. In some embodiments, the cannula shaft  204  comprises a shape memory alloy, such as a nickel titanium alloy (Nitinol™). 
     In some embodiments, the cannula shaft  204  comprises a polymeric material. According to the invention, suitable polymeric materials comprise polyethylene, polyester, polypropylene, acrylic, polycarbonate, and like polymeric materials. 
     In some embodiments, the cannula shaft  204  comprises textured features on at least a portion of the cannula shaft exterior surface  220  to reduce the risk of accidental dislodgment of the cannula sub-system  200  from a biological tissue structure. According to the invention, suitable textured features include, but are not limited to, grooves and ribs. 
     According to the invention, the cannula shaft exterior surface  220  can also comprise an outer coating that facilitates or eases entry into and through body tissue or stabilizes the cannula shaft  204  when positioned in body tissue and/or a body cavity. Suitable coatings comprise, without limitation, polytetrafluoroethylene (FE) and parylene coatings. 
     According to the invention, the cannula shaft  204  can comprise various diameters and lengths. In some embodiments, the cannula shaft  204  comprises an outer diameter in the range of approximately 5-30 mm. More preferably, the outer diameter of the cannula shaft  204  is in the range of approximately 10-20 mm. 
     In some embodiments, the cannula shaft  204  comprises a length in the range of approximately 1-500 mm. More preferably, the length of the cannula shaft  204  is in the range of approximately 75-200 mm. 
     In some embodiments, the cannula shaft wall  222  comprises a thickness in the range of 1-10 mm. More preferably, the thickness of the cannula shaft wall  222  is in the range of approximately 0.25-4 mm. 
     In some embodiments of the invention, the cannula sub-system  200   a  is further configured to insufflate a cavity in a biological tissue structure, e.g., an intra-abdominal cavity. In the noted embodiments, the cannula subsystem  200   a  includes an insufflation sub-system  224  (shown in phantom) that is configured to receive an insufflation management system. 
     In some embodiments, the cannula insufflation sub-system  224  is configured to receive and operate in conjunction with a CONMED® AirSeal® iFS insufflation management system. 
     As illustrated in  FIG.  6   , in one embodiment of the invention, the cannula sub-system  200   a  includes a cannula spacer  230 , which, as discussed in detail below, is configured to receive and position a suture guide sub-system  300  of the invention in a “tissue access configuration.” 
     As further illustrated in  FIG.  6   , the cannular spacer  230  comprises an internal lumen  232  and proximal and distal ends  234 ,  236 . 
     According to the invention, the cannula spacer  230  is preferably configured to engage the proximal end  212  of the cannula base member  202 , wherein the longitudinal axis of the cannula spacer  230  (denoted “ 240 ”) and longitudinal axis  215  of the cannula shaft  204  are coincident. More preferably, the spacer lumen  232  is in an aligned relationship with the cannula continuous lumen  208   c  when the cannula spacer  230  is engaged to the cannula base member  202 . 
     As discussed in detail below, in a preferred embodiment, the cannula spacer lumen  232  and continuous cannula lumen  208   c  are sized and configured to receive a guide sub-system  300  of the invention therein. 
     In some embodiments, the spacer lumen wall  242  comprises at least one continuous groove or notch (not shown) that is in a parallel relationship with longitudinal axis  215  of the cannula shaft  204 . In a preferred embodiment, the groove or notch is configured to receive a cooperating protruding element (not shown) disposed on a guide sub-system  300  when the guide sub-system  300  is positioned in the cannula spacer  230  and sub-system  200 , whereby rotational movement of the suture guide sub-system  300  with respect to the cannula spacer  230  and cannula sub-system  200   a  is constrained. 
     Suture Guide Sub-System 
     Referring now to  FIG.  7 A , there is shown one embodiment of a suture guide sub-system  300   a  of the invention. As illustrated in  FIG.  7 A , the suture guide sub-system  300   a  comprises a guide base  302 , comprising proximal and distal ends  312 ,  314  and a guide shaft  304 , which comprises proximal and distal ends  316 ,  310 , and one embodiment of a tissue positioning sub-system  400   a  of the invention. 
     As further illustrated in  FIG.  7 A , the guide base  302  includes a first suture lumen  306   a  and a first access lumen  308   a , which extend from the proximal end  312  to the distal end  314  of the guide base  302 , and the guide shaft  304  includes a second suture lumen  306   b  and a second access lumen  308   b , which extend from the proximal end  316  of the guide shaft  304  to the proximal end  412  of the notch  410 . 
     In a preferred embodiment of the invention, the first and second suture lumens  306   a ,  306   b  comprise the same diameter and are in an aligned relationship (forming a continuous suture lumen  306   c ) when the guide base  302  is engaged to the guide shaft  304 , i.e., the guide shaft proximal end  316  is in direct communication with, i.e., secured to, the base distal end  314 . 
     As discussed in detail below, the first and second suture lumens  306   a ,  306   b  and, hence, continuous suture lumen  306   c  are sized and configured to receive a suture passer sub-system  500  of the invention therein. 
     In some envisioned embodiments of the invention, continuous suture lumen  306   c  includes at least one continuous suture track or relief (not shown) that is contiguous with the continuous suture lumen  306   c . According to the invention, the suture track facilitates smooth movement of a suture  102  engaged to a suture passer sub-system of the invention, e.g., suture passer sub-system  500 , discussed below, through the continuous suture lumen  306   c , when the suture passer sub-system is inserted in the continuous suture lumen  306   c.    
     In a preferred embodiment of the invention, the it and second access lumens  308   a ,  308   b  also comprise the same diameter and are in an aligned relationship (forming a continuous access lumen  308   c ) when the guide base  302  is engaged to the guide shaft  304 , i.e., the guide shaft proximal end  316  is in direct communication with, i.e., secured to, the base distal end  314 . 
     As discussed in detail herein, the first and second access lumens  3084 ,  308   b  and, hence, continuous access lumen  308  are sized and configured to provide an access port for surgical instruments, e.g., endoscope, that facilitates entry thereof into a body cavity when a guide sub-system  300  of the invention is positioned therein. 
     As further illustrated in  FIG.  7 A , in some embodiments of the invention, the suture guide sub-system  300   a  also comprises a dilating tip  318  that is disposed on the distal end  310  of the guide shaft  304 . According to the invention, the dilating tip  318  can comprise various configurations, including, but not limited to, conical, arrow-tipped and unibit shapes. 
     In some embodiments, the dilating tip  318  comprises a bladed tip. In a preferred embodiment, the dilating tip  318  comprises a bladeless tip to reduce trauma or damage to biological tissue when the guide sub-system  300   a  is deployed therein. 
     In some embodiments, the dilating tip  318  is removeably secured to the distal end  310  of the guide shaft  304 . In some embodiments, dilating tip  318  is permanently secured to the distal end  310  of the guide shaft  304 . 
     According to the invention, the dilating tip  318  can also comprise various conventional materials, including, but not limited to, any of the aforementioned metal and polymeric materials. 
     In some embodiments, the dilating tip  318  comprises a transparent or translucent material that allows an endoscope or other optical device to conduct imaging therethrough. 
     According to the invention, the guide shaft  304  can similarly comprise various diameters and lengths. In a preferred embodiment, the outer diameter of the guide shaft  304  is slightly less than the diameter of the continuous cannula lumen  208   c , whereby the guide shaft  304  can be inserted therein. More preferably, the tolerance or clearance between the guide shaft  304  and continuous cannula lumen  208   c  when the guide shaft  304  is disposed therein is in the range of approximately 0.1-0.5 mm. 
     In some embodiments, the guide shaft  304  preferably comprises a length in the range of approximately 1-500 mm. In a preferred embodiment, the length of the guide shaft  304  is in the range of approximately 75-200 mm. 
     In some embodiments of the invention, the guide shaft  304  similarly comprises textured features on at least a portion of the guide shaft exterior surface  320  to reduce the risk of accidental dislodgment of the suture guide sub-system  300   a  from biological tissue or a tissue structure. 
     In some embodiments, at least a portion of the guide shaft exterior surface  320  comprises an outer coating that cases entry into and through body tissue or stabilizes the guide shaft  304  when positioned in body tissue and/or a body cavity, i.e., restricts translation of the guide shaft  304  when positioned in body tissue. Suitable coatings similarly comprise, without limitation, PTFE and parylene coatings. 
     Referring now to  FIGS.  7 B- 7 H , in some envisioned embodiments, the suture guide sub-system  300   a , i.e., guide shaft  304 , comprises adjustable tissue capture means  405 , which, as discussed in detail below, is configured and positioned to facilitate and enhance tissue capture by the tissue positioning sub-system  400   a.    
     In some embodiments, the distal end  314  of the suture guide sub-system  300   a  is configured to releasably engage the proximal end  212  of the cannula sub-system base member  20 . 
     In some embodiments, the suture guide sub-system  300   a  further comprises an operator actuated lock and release mechanism that operates in conjunction with cannula sub-system  200   a  to removeably secure the suture guide sub-system  300   a  to the cannula sub-system  200   a . According to the invention, the lock and release mechanism can comprise any conventional lock and release mechanism applicable to a TAC system  100  of the invention, including, without limitation, a disengageable push lock or plunger lock. 
     As indicated above, in a preferred embodiment of the invention, the suture guide sub-systems  300  of the invention further comprise a tissue positioning sub-system  400 , which is a seminal feature of the suture guide sub-systems  400  and, hence, TAC systems  100  of the invention. 
     Referring now to  FIGS.  8 A- 8 C , one embodiment of the tissue positioning sub-system  400   a  of the invention will be described in detail. 
     As illustrated in  FIGS.  8 A- 8 C , in a preferred embodiment of the invention, the tissue positioning sub-system  400   a  comprises a tissue positioning notch  410  that comprises proximal and distal ends  412 ,  414 . In some embodiments, the notch  410  preferably has a length from the proximal and distal ends  412 ,  414  thereof in the range of approximately 1-15 mm. 
     As discussed in detail below, during operation of a TAC system  100  that includes suture guide sub-system  300   a , the tissue positioning notch  410  is configured to engage and retain at least a portion of biological tissue between the proximal and distal ends  412 ,  414  of the notch  410 , when the suture guide sub-system  300   a  is at least partially withdrawn from a biological tissue structure, e.g., an abdominal cavity. 
     As indicated above, in some embodiments, the suture guide sub-system  300   a  further comprises adjustable tissue capture means  405  that is configured and positioned to facilitate and enhance engagement of biological tissue by the tissue positioning sub-system  400   a , i.e., within tissue positioning notch  410 . 
     Referring now to  FIGS.  7 B- 7 D , there is shown one embodiment of an adjustable tissue capture means  405  of the invention. As illustrated in  FIGS.  7 B- 7 D , the adjustable tissue capture means  405  comprises an outer sleeve member  405   a  (shown in phantom in  FIGS.  7 C and  7 D ) that is sized and configured to be slidably positioned over guide shaft  304  and translate linearly along the central axis of the guide shaft  304 , as shown by arrow LA, whereby the outer sleeve member  405   a  modulates the size of the opening of the tissue positioning notch  410 , as shown in  FIG.  7 D . 
     As further illustrated in  FIG.  7 B , the outer sleeve member  405   a  comprises proximal and distal ends  407   a ,  407   b . In a preferred embodiment, the distal end  407   b  of the outer sleeve member  405  comprises a shape that substantially corresponds to the shape of notch distal end  414 . 
     In a preferred embodiment, the outer sleeve member  405   a  and the guide shaft  304  further comprise cooperating lock and release engagement means that is configured to position and maintain the outer sleeve member  405   a  in pre-determined pre-release and actuation, e.g., tissue engagement, positions on the suture guide sub-system  300   a.    
     In some embodiments, the cooperating lock and release engagement means comprises a cooperating dimple and recess system, wherein at least one dimple member  409  is disposed on the outer sleeve member  405   a  luminal (or interior) surface, as shown in  FIG.  7 B , which is configured and positioned to engage at least one pre-formed recess disposed on the exterior surface  320  of the guide shaft  304 . 
     In a preferred embodiment of the invention, the outer sleeve member  405  is adapted to be manually released from and positioned by the dimple and recess system. 
     Referring now to  FIGS.  7 E- 7 H , there is shown another embodiment of an adjustable tissue capture means  405  of the invention. As illustrated in  FIGS.  7 E- 7 H , the adjustable tissue capture means  405  comprises a jaw member  405   b  that is sized and configured to be slidably positioned within notch  400   a  and translate linearly along the central axis of the guide shaft  304 , as shown by arrow LA, whereby the proximal jaw member  405   b  similarly modulates the size of the opening of the tissue positioning notch  410 , as shown in  FIG.  7 H . 
     Referring now to  FIGS.  7 E and  7 F , in a preferred embodiment of the invention, the jaw member  405   b  comprises an outer shape that corresponds with the outer shape of the guide shaft  304 . 
     As illustrated in  FIGS.  7 E and  7 F , the jaw member  405   b  further comprises proximal and distal ends  420   a ,  420   b , a lumen  306   c , which is in alignment with continuous suture lumen  306   c , and a drive shaft  424 . 
     In a preferred embodiment, the jaw member  405   b  further comprises guide shaft guides  422   a ,  422   b , which are sized and configured to seat and translate in cooperating guide shaft seats  305   a ,  305   b  to facilitate smooth translation of the jaw member  405   b  in the notch region. 
     As illustrated in  FIGS.  70  and  7 H , drive shaft  424  is connected to the proximal end  420   b  of the jaw member  405   b  and extends through the guide shaft  304 . In one embodiment, such as illustrated in  FIGS.  70  and  7 H , the drive shaft  424  extends and translates through the continuous access lumen  308   c.    
     As further illustrated in  FIGS.  7 G and  7 K  the drive shaft  424  extends out of the guide shaft  304  to facilitate actuation of the drive shaft  424  and, hence, jaw member  405   b.    
     According to the invention, the drive shaft  424  and, hence, jaw member  405   b  can be modulated via various conventional actuation means, including, without limitation, manual actuation means. 
     In a preferred embodiment, the jaw member  405   b  and the guide shaft  304  similarly further comprise cooperating lock and release engagement means that is configured to position and maintain the jaw member  405   b  in pre-determined pre-release and actuation, e.g., tissue engagement, positions. 
     According to the invention, various conventional lock and release engagement means can be employed within the scope of the invention to position and maintain the jaw member  405   b  in pre-determined pre-release and actuation positions, including, without limitation, ratchet and one-way ball or roller bearing clutch systems. 
     As further illustrated in  FIGS.  7 A and  8 A- 8 C , disposed proximate the proximal and distal ends  412 ,  414  of the notch  410  are continuous suture lumen  306   c  and suture lumen  306   d , which is in an aligned relationship with continuous suture lumen  306   c.    
     Referring now to  FIGS.  8 A- 8 C , in a preferred embodiment, the tissue positioning sub-system  400   a  comprises a capture clip  402  that is positioned at an internal location of the guide shaft  304  proximate the distal end  414  of the tissue positioning notch  410 . 
     As illustrated in  FIGS.  8 A- 8 C , the capture clip  402  includes an extended region  404  that is disposed proximate the tissue positioning notch  410  such that the extended region  404  intersects the longitudinal axis of suture lumen  306   d , where the extended region  404  forms a suture capture door (or system)  403 . According to the invention, the capture door  403  is positioned and configured to capture a suture transferred into suture lumen  306   d  of the guide shaft  304  by a tissue passer sub-system  500  during operation of a TAC system  100  of the invention, i.e., when a suture passer sub-system  500  of the invention guides a suture  102  into and through continuous suture lumen  306   c , notch  410  and suture lumen  306   d , the extended region  404  of the capture clip  402  (i.e., suture capture door  403 )transitions, i.e., is deflected or flexed, to an open position by the suture passer sub-system  500  as the distal end of the suture passer sub-system  500  (with a suture  102  engaged thereto) traverses beyond the distal end  414  of the tissue positioning notch  410 . When the suture passer sub-system  5  is withdrawn from suture lumen  306   d , the extended region  404  of the capture clip  402  (i.e., suture capture door  403 ) transitions back to a closed position and captures the suture  102 . 
     In a preferred embodiment of the invention, the capture clip  402  further comprises an open region  408  which, when the capture clip  402  is positioned in the guide shaft  304 , is in an aligned relationship with access lumen  308   d  (which is in an aligned relationship with continuous access lumen  308   c ) allows surgical instruments, such as an endoscope, to enter into and through access lumen  308   d  and guide shaft  304 . 
     According to the invention, the capture clip  402  can further comprise structural features, such as formed ribs, which are designed to enhance the structural integrity of the thin section created by the notch  410 . 
     In a preferred embodiment of the invention, the force (F) required to transition the extended region  404  of the capture clip  402  from a closed position to an open position is in the range of approximately 0.1-5.0 lbs f . 
     According to the invention, the capture clip member  402  can comprise various materials, including, without limitation, metal and polymeric materials. Thus, in some embodiments, the capture clip member  402  comprises stainless steel. In some embodiments, the capture clip  402  comprises a shape memory alloy, such as a nickel titanium alloy (e.g., Nitinol™). 
     In some embodiments, the capture clip  402  comprises a polymeric material, such as one of the aforementioned polymeric materials. 
     In some embodiments, not shown, the capture door system  403  comprises a manually operated gating mechanism. In such embodiments, the suture guide sub-system  300   a  comprises a slide mechanism that is configured to transition the extended region  404  of the capture clip  402  from a closed position to an open position. 
     Referring now to  FIGS.  9  and  10   , there is shown another embodiment of a suture guide sub-system  300   b  of the invention. As illustrated in  FIG.  9   , the guide sub-system  300   b  similarly comprises a guide base  323 , comprising proximal and distal ends  328 ,  330 , and a guide shaft  322 , which comprises proximal and distal ends  324 ,  326 , and a tissue positioning sub-system  400   b.    
     As further illustrated in  FIGS.  9  and  10   , the guide base  323  includes a first suture lumen  332   a , which extends from the proximal end  328  to the distal end  330  of the guide base  323 , and the guide shaft  322  includes a second suture lumen  332   b , which extends from the proximal end  324  of the guide shaft  322  to the proximal end  412  of the notch  410 . 
     In a preferred embodiment of the invention, the first and second suture lumens  332   a ,  332   b  similarly comprise approximately the same diameter and are in an aligned relationship (forming a continuous suture lumen  332   c ) when the guide base  323  is engaged to the guide shaft  322 , i.e., the guide shaft proximal end  324  is in direct communication with, i.e., secured to, the base distal end  330 . 
     As discussed in detail below, the first and second suture lumens  332   a ,  332   b  and, hence, continuous suture lumen  332   c  are also sized and configured to receive a suture passer sub-system  500  of the invention therein. 
     In a preferred embodiment of the invention, continuous suture lumen  332   c  includes at least one continuous suture track or relief that is contiguous with (and, hence, in a parallel relationship with) the continuous suture lumen  332   c . According to the invention, the suture track similarly facilitates smooth movement of a suture  102  engaged to a suture passer sub-system  500  of the invention through the continuous suture lumen  332   c , when the suture passer sub-system  500  is inserted in the continuous suture lumen  332   c.    
     In some embodiments, the continuous suture lumen  332   c  comprises a single suture track or relief. 
     As illustrated in  FIG.  11   , in a preferred embodiment of the invention, continuous suture lumen  332   c  comprises three (3) suture tracks or reliefs  336   a ,  336   b ,  336   c.    
     According to the invention, the distal end  326  of the guide shaft  322  can similarly comprise various configurations, including, but not limited to, conical, pyramid and unibit shapes. 
     In some embodiments, the distal end  326  comprises a bladed tip. In a preferred embodiment, the distal end  326  comprises a bladeless tip to reduce trauma or damage to biological tissue when the suture guide sub-system  300   b  is deployed therein. 
     According to the invention, the guide shaft  322  can similarly comprise various diameters and lengths. In some embodiments, the diameter of the guide shaft  322  is similarly slightly less than the diameter of the continuous cannula lumen  20 , whereby the guide shaft  322  can be inserted therein. More preferably, the tolerance or clearance between the guide shaft  322  and continuous cannula lumen  208   c  when the guide shaft  322  in disposed therein is similarly in the range of approximately 0.1-1.0 mm. 
     According to the invention, the suture guide sub-system  300   b  can also comprise a stand-alone suture guide system, i.e., the guide sub-system  300   b  can be employed to directly access and close tissue without the use of a cannula sub-system  200 . 
     In some embodiments, the guide shaft  322  similarly preferably comprises a length in the range of approximately 1-500 mm. In a preferred embodiment, the length of the guide shaft  322  is in the range of approximately 100-200 mm. 
     In some embodiments of the invention, the guide shaft  322  similarly comprises textured features on at least a portion of the guide shaft exterior surface  334  to reduce the risk of accidental dislodgment of the suture guide sub-system  300   b  from biological tissue or tissue structure. 
     In some embodiments, at least a portion of the guide shaft exterior surface  334  comprises an outer coating that eases entry into and through body tissue or stabilizes the guide shaft  322  when positioned in body tissue and/or a body cavity, i.e., restricts translation of the guide shaft  322  when positioned in body tissue. Suitable coatings similarly comprise, without limitation, PTFE and parylene coatings. 
     In some embodiments, the suture guide sub-system  300   b  further comprises an operator actuated lock and release mechanism that operates in conjunction with cannula sub-system  200  to removeably secure the suture guide sub-system  300   b  to the cannula sub-system  200 . According to the invention, the lock and release mechanism can similarly comprise any conventional lock and release mechanism applicable to a TAC system  100  of the invention, including, without limitation, a disengageable push lock or plunger lock. 
     As indicated above, in a preferred embodiment of the invention, the suture guide sub-system  300   b  also comprises a tissue positioning sub-system  400   b.    
     Referring now to  FIGS.  12 A,  12 B and  13   , the tissue positioning subsystem  400   b  will be described in detail. 
     As illustrated in  FIGS.  12 A,  12 B and  13   , in a preferred embodiment of the invention, the tissue positioning sub-system  400   b  similarly comprises tissue positioning notch  410 , which, as indicated above, is configured to engage and retain at least a portion of biological tissue between the proximal and distal ends  412 ,  414  of the notch  410  when the guide sub-system  300   b  is at least partially withdrawn from a biological tissue structure, e.g., an abdominal cavity. 
     As further illustrated in  FIGS.  9 , 10 , 12 A and  12 B , disposed proximate the proximal and distal ends  412 ,  414  of the notch  410  are continuous suture lumen  332   e  and suture lumen  332   d , which is in an aligned relationship with continuous suture lumen  332   e.    
     As illustrated in  FIG.  11   , in a preferred embodiment, suture lumen  332   d  also comprises continuous grooves or notches  336   a ,  336   b ,  336   c . In some embodiments, suture lumen  332   d  comprises a plurality of continuous grooves or notches. In some embodiments, the suture lumen  332   d  comprises a single continuous groove or notch. 
     Referring now to  FIGS.  12 A,  12 B and  13   , in a preferred embodiment, the tissue positioning subsystem  400   b  also comprises a capture clip  416  that is positioned at an internal location of the guide shaft  322  proximate the distal end  414  of the tissue positioning notch  410 . 
     As illustrated in  FIGS.  12 A,  12 B and  13   , the capture clip  416  similarly includes an extended region  420  that is disposed proximate the suture lumen  332   d , where the extended region  420  similarly forms a suture capture door (or system)  418 . 
     In a preferred embodiment, the suture capture door  418  similarly facilitates the capture of a suture transferred into suture lumen  332   d  of the guide shaft  322  by a tissue passer sub-system  500  in a manner that is similar to suture capture door  403  discussed above, i.e., when a suture passer sub-system  500  of the invention guides a suture  102  into and through continuous suture lumen  332   e , notch  410  and suture lumen  332   d , the extended region  420  of the capture clip  416  transitions, i.e., is deflected or flexed, to an open position by the suture passer sub-system  500  as the distal end of the suture passer sub-system  500  (with a suture  102  engaged thereto) traverses beyond the distal end  414  of the tissue positioning notch  410 . When the suture passer sub-system  500  is withdrawn from suture lumen  332   d , the extended region  420  of the capture clip  416  (i.e., suture capture door  418 )transitions back to a closed position and captures the suture  102 . 
     According to the invention, the capture clip  416  can similarly comprise structural features, such as formed ribs, that are designed to enhance the structural integrity of the notch  410  region. 
     In a preferred embodiment of the invention, the force (F) required to transition the extended region  420  of the capture clip  416  from a closed position to an open position is similarly in the range of approximately 0.1-5.0 lbs f . 
     According to the invention, the capture clip member  416  can also comprise various materials, including, without limitation, metal and polymeric materials. Thus, in some embodiments, the capture clip  416  comprises stainless steel. In some embodiments, the capture clip  416  comprises a shape memory alloy, such as a nickel titanium alloy (e.g., Nitinol™). 
     In some embodiments, the capture clip  416  comprises a polymeric material, such as one of the aforementioned polymeric materials. 
     According to the invention, the suture capture door system  418  can similarly comprise a manually operated gating mechanism. In such embodiments, the suture guide sub-system  300   b  includes a slide mechanism that is configured to transition the extended region  420  of the capture clip  416  from a closed position to an open position. 
     Suture Passer Sub-System 
     Referring now to  FIGS.  14 - 16 ,  17 A- 17 C,  18  and  19 A- 19 D , there is shown one embodiment of a suture passer sub-system  500   a  of the invention. As illustrated in  FIGS.  7  and  9   , and discussed in detail herein, in a preferred embodiment, the suture passer sub-system  500   a  is adapted to cooperate with a suture guide sub-system  300  of the invention, such as suture guide sub-systems  300   a  and  300   b.    
     As illustrated in  FIGS.  14 - 16   , in a preferred embodiment, the suture passer sub-system  500   a  comprises a housing (or handle)  510 , actuator  530 , compression spring  534 , suture deployment shaft (i.e., needle)  540  and tubular cannula shaft  560 , which is configured to receive the suture deployment shaft  540  therein. 
     As discussed in detail below and illustrated in  FIG.  18   , the suture deployment shaft  540  includes suture deployment and capture means  550  that is disposed on the distal end of the suture deployment shaft  540 . In a preferred embodiment, the suture deployment and capture means  550  is configured to capture and removably secure a suture  102  therewith. 
     In some embodiments, the housing  510  comprises proximal and distal ends,  512 ,  514  at least one, more preferably, two (2) finger contours  516   a ,  516   b  to facilitate a controlled grip and manipulation of the suture passer sub-system  500   a.    
     As illustrated in  FIGS.  14  and  15   , the actuator  530  and suture deployment shaft  540  are preferably joined (or coupled) via an actuator-deployment shaft pin  532 , whereby, when a sufficient actuation force is exerted on the actuator  530 , the suture deployment shaft  540  transitions from a retracted position (or state) to an extended position. 
     As also illustrated in  FIGS.  14  and  15   , the housing  510  further comprises a guide slot  518 , which is preferably disposed adjacent finger contours  516   a ,  516   b . According to the invention, the guide slot  518  is positioned and configured to receive the actuator-deployment shaft pin  532  and control travel of the actuator  530  and, hence, suture deployment shaft  540 . 
     Referring now to  FIG.  16   , the interior of the housing  510  (denoted generally “ 520 ”) is configured to receive, contain and provide structural support for the actuator  530 , suture deployment shaft  540  and the compression spring  534 . The distal end  514  of the housing  510  is further configured to receive and secure the cannula shaft  560  to the housing  510 . 
     According to the invention, the compression spring  534  is positioned and configured to exert a spring force (denoted by arrow F s ) on the actuator  530  and, thereby, suture capture shaft  540 , when the actuator  530  is in a static (i.e., retracted) state. 
     Preferably, the actuator  530  is able to axially advance the suture deployment shaft  540  inside of the cannula shaft  560  from a retracted position to an extended position with minimal force exerted on the actuator  530  with an operator&#39;s thumb. Thus, in a preferred embodiment, the spring force (F s ) exerted on the actuator  530  by the compression spring  534  when the actuator  530  is in a static state is in the range of approximately 0.5-4.0 lbs f . 
     As indicated above, in a preferred embodiment, the housing guide slot  518  is configured and sized to limit axial advancement of the actuator-deployment shaft pin  532  and, hence, suture deployment shaft  540 , when an actuation force is exerted on the actuator  530  by an operator. Thus, full thumb force can be exerted on the actuator  530  by an operator without concern that the suture deployment shaft  540  will overextend. 
     Referring now to  FIG.  17 A , in a preferred embodiment of the invention, the cannula shaft  560  preferably includes a beveled edge  564  on the distal end  562  thereof which is configured to pierce through tissue to facilitate suture passage. In a preferred embodiment of the invention, the angle “γ” of the beveled edge  564  with respect to the longitudinal axis of the cannula shaft  560  (denoted “C LA ”) is in the range of 10-40°. 
     According to the invention, the edge  564  of cannula shaft  560  can comprise various alternative shapes to facilitate piercing though tissue. 
     Referring now to  FIGS.  17 B and  17 C , in some embodiments of the invention, the cannula shaft (now denoted “ 561 ”) further comprises a pair of dimples  567   a ,  567   b  that are preferably disposed on opposing sides of the cannula shaft  561 . According to the invention, the dimples  567   a ,  567   b  are sized and positioned on the cannula shaft  561  to facilitate the release of a captured suture  102  by the suture deployment and capture means  550  of the suture passer sub-system  500 S, as discussed below. 
     As indicated above, the suture deployment shaft  540  includes suture deployment and capture means  550  that is configured to capture and removably secure a suture  102  therewith. As illustrated in  FIG.  1   , in a preferred embodiment, the suture deployment and capture means  550  comprises a tong member  551  having an elongated top portion  552  and a cooperating elongated bottom portion  554 . 
     In a preferred embodiment of the invention, the elongated top and bottom portions  552 ,  554  of the tong member  551  are configured or pre-shaped to transition from a restrained static or pre-deployment configuration when the suture deployment shaft  540  is in a retracted position, wherein, as illustrated in  FIG.  19 C , the tong member  551  is disposed in the cannula lumen  563 , to an expanded (or unrestrained) configuration, when the suture deployment shaft  540  is in an extended position and the tong member  551  is extending out of the cannula lumen  563 , as illustrated in  FIG.  18   . 
     As further illustrated in  FIG.  18   , when the tong member  551  is in the extended position, the elongated top portion  552  is disposed at an angle θ with respect to the elongated bottom portion  554 , whereby an open region (denoted “OR”) is provided between the elongated top and bottom portions  552 ,  554  of the tong member  551 . 
     As also illustrated in  FIG.  18   , in a preferred embodiment, the elongated top portion  552  of the tong member  551  comprises a first substantially linear segment  556   a , a second substantially linear segment  556   b , which is disposed at an angle β with respect to first segment  556   a , and a linear distal end  556   c , which is disposed at an angle λ with respect to the linear segment  556   b.    
     In a preferred embodiment, angle β is in the range of 5°-15° to, as discussed below, provide a supplemental suture engagement force upon an engaged suture  102  when the tong member  551  is being retracted into the cannula lumen  563 . 
     In a preferred embodiment, angle λ is in the range of 2°-30° to, as also discussed below, facilitate release of a suture  102  when the tong member  551  is in a restrained state, i.e., a static or pre-deployment configuration, in the cannula lumen  563 . 
     Referring now to  FIGS.  19 A- 19 D , engagement of a suture  102  with the tong member  551  and release of the suture  102  therefrom will now be described in detail. 
     According to the invention, to facilitate initial suture capture, the suture deployment shaft  540  is axially advanced from a static/retracted position in the cannula lumen  563  to an extended position shown in  FIG.  18    by exerting an actuation force on the actuator  530  in the direction denoted by arrow F A , wherein the tong member  551  is exposed. As illustrated in  FIG.  18   , a suture  102  can then be positioned in the open region “OR” (i.e., seated in the open region) of the tong member  551 . 
     After the suture  102  is seated in the open region “OR” of the tong member  551 , the actuator  530  is released and the spring force F s  exerted by the spring  534  on the actuator  530  withdraws (or retracts) the suture deployment shaft  540  and, hence, tong member  551  with the suture  102  connected thereto into the cannula shaft  560 , as shown in  FIGS.  19 A and  19 B . 
     As illustrated in  FIG.  19 A , during an initial retraction stage of the tong member  551 , the elongated top and bottom portions  552 ,  554  of the tong member  551  collapse and capture the suture  102 , and, preferably, pull the suture  102  against the beveled distal end  562  of the cannula  560 . 
     As illustrated in  FIG.  19 B , further retraction of the tong member  551  enables the elongated bottom portion  554  of the tong member  551  to release the suture  102 , while the elongated top portion  552 , due to its greater bending moment, exerts a greater force on the suture  102  to pull the suture  102  against the beveled distal end  562  of the cannula  560 . 
     As illustrated in  FIG.  19 C , further retraction of the tong member  551  enables the elongated top portion  552  of the tong member  551  to collapse and secure the suture  102  in and against the cannula shaft lumen  563 . In a preferred embodiment of the invention, the lateral gap between the elongated portion  552  of the tong member  551  and the inside diameter of the cannula  560  ranges from 0.1 mm to 1.0 mm per side. A sufficient lateral gap enables the collapse of the suture  102 , thus preventing premature release of the suture  102 . 
     According to the invention, the retention force exerted on a suture  102  by the elongated top portion  552  of the tong member  551  when the tong member  551  is withdrawn into the cannula shaft  560  and, hence, is in a static/retracted position, wherein, as shown in  FIG.  19 C , the suture  102  is disposed between the elongated top portion  552  and the surface of the cannula shaft lumen  563 , is preferably in the range of 0.01-5.0 lbs f  to, as shown in  FIG.  19 D  and discussed in detail below, allow the suture  102  to be readily released from the tong member  551  when captured by a suture capture door (i.e.,  403  or  418 ) of a suture guide sub-system  300  of the invention. 
     In some embodiments of the invention, the maximum retention force exerted against a suture  102  by the elongated top portion  552  of the tong member  551  when the tong member  551  is withdrawn into the cannula shaft  560  is less than the closure force (F) of the suture capture door ( 403  and  418 ) of the suture guide sub-system  300 . 
     According to the invention, by virtue of the design of the suture capture doors  403 ,  418 , suture  102  can also be released from the tong member  551  and captured by a suture capture door  403  or  418  when the retention force exerted on a suture  102  by the elongated top portion  552  of the tong member  551  when the tong member  551  is withdrawn into the cannula shaft  560  is greater than the closure force (F) of the suture capture door ( 403  and  418 ) of the suture guide sub-system  300 . 
     In a preferred embodiment of the invention, the beveled edge  564  of the cannula shaft  560  acts as a strain relief when force is pulled on the suture  102  in a proximal direction, such as when the suture capture shaft  540  with suture  102  engaged thereto is advanced through tissue. However, due to the shallow angle λ at the distal end of the elongated top portion  552  of the tong member  551 , the force required to release the suture  102  is low, whereby the suture  102  can be readily released and captured by a suture capture door system (i.e.,  403  or  418 ) of a suture guide sub-system  300  of the invention. 
     In the embodiments of the cannula shaft  561  shown in  FIGS.  17 B and  17 C , where the cannula shaft  561  includes dimples  567   a ,  567   b , the restricted path section or region in the cannula lumen provided by the dimples  567   a ,  567   b , would allow the elongated top and bottom portions  552 ,  554  of the tong member  551  to freely traverse through the restricted path region, but would aid in the release of the suture  102  when disposed proximate the restricted region, as shown in  FIGS.  20 A and  20 B . 
     According to the invention, the suture deployment shaft  540  and tubular cannula shaft  560  can comprise various conventional materials, such as polymeric materials and metal alloys. In a preferred embodiment, the suture deployment shaft  540  and tubular cannula shaft  560  comprise stainless steel. 
     The housing  510  and actuator  530  of the suture passer sub-system  500   a  can similarly comprise various conventional materials. In a preferred embodiment, the housing  510  and actuator  530  comprise a polymeric material. According to the invention, suitable polymeric materials include, without limitation, any of the aforementioned polymeric materials. 
     TAC System Operation 
     Operation of a TAC system  100  of the invention will now be described in detail. 
     As set forth in detail herein, the TAC systems  100  are configured to (i) pierce through biological tissue and provide access to internal structures; particularly, intra-abdominal structures, to facilitate entry through the tissue with surgical instruments and interaction of the surgical instruments with internal structures, and (ii) close an openings in the biological tissue, more preferably, approximate and/or ligate and/or fixate and close openings in biological tissue; particularly, laparoscopic ports or incisions in biological tissue. The TAC systems  100  of the invention thus preferably comprise two modes: (i) a “tissue access” mode and (ii) a “tissue closure” mode. 
     Referring now to  FIG.  21   , there is shown a flow chart illustrating a preferred method  600  of the invention for (i) piercing through biological tissue and providing access to internal structures using a “tissue access” assembly of a TAC system  100  of the invention and (ii) closing an opening in the tissue using a “tissue closure” assembly of the TAC system  100 . 
     In the preferred method described herein, the “tissue access” assembly comprises cannula sub-system  200  and spacer  230 , shown in  FIGS.  5  and  6   , and suture guide sub-system  300   a , shown in  FIG.  7 A , and the “tissue closure” assembly comprises cannula sub-system  200 , suture guide sub-system  300 , and suture passer sub-system  500   a , shown in  FIG.  14   . 
     For purposes of describing the preferred method, the tissue structure pierced and closed with the TAC system  100  comprises an abdominal tissue wall  12 , comprising an adipose tissue layer  54 , a muscle/fascia layer  56  and a peritoneum layer  58 . The abdominal wall tissue (denoted collectively “ 16 ” herein) also comprises a top skin layer (not shown). 
     As stated above, the TAC systems  100  of the invention and, hence, methods employing same are not, however, limited to solely piercing and closing abdominal tissue and structures and/or surgical procedures relating thereto. Indeed, the TAC systems  100  of the invention and methods employing same can also be readily employed to pierce into and through other tissue structures (and provide access to internal structures) and close openings in other tissues and tissue structures. 
     As illustrated in  FIG.  21   , after an incision is made in the biological tissue (and, hence, tissue structure), the TAC system  100  identified above is configured in a “tissue access configuration” and inserted into (and, preferably, through) the tissue structure, i.e., the opening provided by the incision [ 601 ]. 
     As illustrated in  FIGS.  22 ,  23 A and  23 B , after the “tissue access” assembly of the TAC system  100  is inserted into the tissue structure, the TAC system  100  is re-configured into a partial “tissue closure” assembly [ 602 ], i.e., spacer  230  is removed, wherein tissue positioning sub-system  400   a  is exposed. 
     The partial “tissue closure” assembly, i.e., assembled cannula and suture guide sub-systems  200 ,  300   a , is then positioned in an opening  11  (see  FIG.  24   ) of a biological tissue structure such that the exposed tissue positioning sub-system  400   a  is disposed proximate to and engages a first portion of biological tissue  60   a  [ 603 ]. In the illustrated embodiment, the first portion of biological tissue  60   a  comprises a portion of intra-abdominal tissue, more preferably, a portion of muscle/fascia and peritoneum layers  56 ,  58 . 
     In some embodiments of the invention, wherein suture guide sub-system  300   a  is employed and the suture guide sub-system  300   a  includes adjustable tissue capture means  405 , after the first portion of biological tissue  60  is engaged by the tissue positioning sub-system  400   a , the adjustable tissue capture means  405  is actuated, wherein the first portion of biological tissue  60   a  is engaged by the adjustable tissue capture means  405 . 
     Referring back to  FIG.  21   , after the first portion of biological tissue  60   a  is engaged by the tissue positioning sub-system  400   a  [ 603 ], the suture passer sub-system  500  is inserted into the suture guide sub-system  300   a , i.e., the tubular cannula shaft  560  of the suture passer sub-system  500   a  is inserted into the continuous suture lumen  306   c  of the suture guide sub-system  300   a  [ 604 ], whereby the complete “tissue closure” assembly of the TAC system  100  referenced above is formed. 
     A first portion of suture  102  is then connected to the suture deployment shaft (or needle)  540  of the suture passer sub-system  500   a  and the cannula shaft  560  with the suture deployment shaft  540  (with the first portion of suture  102  engaged thereto) disposed therein is inserted into and through the first portion of biological tissue  60   a  and suture capture door  403  of the tissue positioning sub-system  400   a  [ 605 ]. 
     After the first portion of suture  102  is inserted into and through the first portion of biological tissue  60   a  and suture capture door  403  of the tissue positioning sub-system  400   a  with the suture passer sub-system  500   a  [ 605 ], the cannula shaft  560  (and, hence, suture deployment shaft  540 ) is withdrawn through of the suture capture door  403  and out of the first portion of biological tissue  60   a  [ 606 ], whereby the first portion of suture  102  is routed through the first portion of biological tissue  60   a  and captured or ensnared by the suture capture door  403  of the tissue positioning sub-system  400   a.    
     As illustrated in  FIGS.  23 A and  23 B , after the cannula shaft  560  of the suture passer sub-system  500   a  is withdrawn out of the first portion of biological tissue  60   a  [ 606 ], the suture passer sub-system  500 S is further withdrawn in continuous suture lumen  306   c  and, preferably, out of the tissue guide sub-system  300   a , and the “tissue closure” assembly of the TAC system  100  is rotated, preferably, rotated approximately 180° [ 607 ], whereby a contralateral second portion of biological tissue  60   b  is engaged by the tissue positioning sub-system  400   a  of the suture guide sub-system  300   a.    
     Referring to  FIG.  233   , after the “tissue closure” assembly of the TAC system  100  is rotated [ 607 ], a second portion of suture  102  is connected to the suture deployment shaft  540  of the suture passer sub-system  5006  and the cannula shaft  60  with the suture deployment shaft  540  (with the second portion of suture  102  engaged thereto) disposed therein is inserted into and through a second portion of biological tissue  60   b  and past the suture capture door  403  [ 608 ]. 
     After the second portion of suture  102  is inserted into and through the second portion of biological tissue  60   b  and suture capture door  403  with the suture passer sub-system  500   a  [ 608 ], the cannula shaft  560  is similarly withdrawn through suture capture door  403  and out of the second portion of biological tissue  60   b , whereby the second portion of suture  102  is routed through the second portion of biological tissue  60   b  and ensnared by the suture capture door  403  of the tissue positioning sub-system  400   a  [ 609 ]. Both the first and second sections of suture  102  are now ensnared by the suture capture door  403  of the tissue positioning sub-system  400   a.    
     Referring now to  FIG.  24   , after the suture passer sub-system  500   a  is withdrawn out of the second portion of biological tissue  60   b  [ 609 ], the assembled cannula and suture guide sub-systems  200 ,  300   a  (i.e., partial “suture closure” assembly) are also withdrawn from the biological tissue structure, e.g., abdominal wall  12 , with the first and second portions of suture  102  ensnared by the suture capture door system  403  of the tissue positioning sub-system  400   a  [ 610 ]. 
     After the complete “tissue closure” assembly of the TAC system  100  is withdrawn from the biological tissue structure [ 610 ], the first and second portions of the suture  102  are released from the suture door  403  and drawn together or tied, e.g., a stitch loop is formed, whereby the first and second portions of biological tissue  60   a ,  60   b  are drawn together and the opening  11  in the tissue structure is closed, more preferably, ligated, fixated and closed [ 611 ]. 
     According to the invention, a further tissue passer sub-system  500  that can also be employed with a TAC system  100  of the invention, i.e., a“tissue closure” assembly thereof, is disclosed in Applicant&#39;s U.S. Pat. No. 9,301,748, which is also expressly incorporated herein in its entirety. 
     According to the invention, the method  600  illustrated in  FIG.  21    and described above can also be performed using suture guide sub-system  300   b . The opening in the tissue structure can also be closed using suture guide sub-system  300   b  as a stand-alone tissue closure system. 
     As discussed in detail below, the opening in the tissue structure can also be closed using a further tissue closure system of the invention. 
     Alternative Tissue Closure Systems 
     Referring now to  FIGS.  25  and  26   , there is shown an alternative suture guide system  300   c  that can be employed with a TAC system  100  of the invention, i.e., a “tissue closure” assembly of a TAC system  100 , or as a stand-alone suture guide and tissue closure system. 
     As illustrated in  FIGS.  25  and  26   , in a preferred embodiment of the invention, the suture guide system  300   c  comprises a housing  350 , having an elongated guide region  355  with proximal and distal ends  352 ,  354  and a handle  356 , a pair of sliders  360   a ,  360   b , a pair of suture snares  372   a ,  372   b  and a suture  102 . According to the invention, the distal end  354  of the housing elongated guide region (beyond the tissue positioning region  400   c , discussed below) functions as a safety shield to ensure that the suture cannula shafts  368   a ,  368   b , discussed below, do not overextend and puncture undesired tissue. 
     As illustrated in  FIG.  26   , each slider  360   a ,  360   b  includes an actuator  367   a ,  367   b  and a suture cannula shaft  368   a ,  368   b , which is operatively connected thereto. In a preferred embodiment, the actuators  367   a ,  367   b  comprise a raised top region  361   a ,  361   b , which is configured to facilitate operation of the actuators  367   a ,  367   b  by an operator&#39;s thumb (or other finger), and a curved bottom region  363   a ,  363   b  comprising a shape that cooperates with the outer shape of the system housing  350  (see also  FIG.  25   ). 
     As further illustrated in  FIG.  26   , each suture snare  370   a ,  370   b  includes an elongated shaft  371   a ,  371   b , having a flexible hooked end  374   a ,  374   b  on one end and a flexible suture capture member  372   a ,  372   b  on the opposing end. 
     As further illustrated in  FIG.  26   , the housing  350  comprises first and second housing sections  350   a ,  350   b , i.e., a two-piece structure, which, when operatively connected, form an internal region  365  that is configured to receive and guide suture snares  370   a ,  370   b  and an internal lumen  366  that is configured to receive and guide the suture cannula shafts  368   a ,  368   b . In a preferred embodiment, each housing section  350   a ,  350   b  comprises a guide slot  351   a ,  351   b  that is configured to receive a respective one of the flexible looped ends  374   a ,  374   b  of a suture snare  370   a ,  370   b.    
     Referring back to  FIG.  25   , the housing  350  two-piece structure, when operatively connected, further forms a tissue positioning (or engagement) region, i.e., notch,  400   c , which, as discussed in detail below, is similarly configured to close biological tissue, more preferably, approximate and/or ligate and/or fixate and close biological tissue; particularly, laparoscopic ports or incisions in biological tissue. 
     Operation of the suture guide system  300   c  will now be described in detail. 
     Although operation of the suture guide system  300   c  is described herein in connection with closing laparoscopic ports, the suture guide system  300   c  is not limited to merely closing laparoscopic ports. According to the invention, the suture guide system  300   c  can also be employed with or implemented in other surgical apparatus, such as a catheter or other flexible housing where flexible components of which can be used to facilitate accessing remote anatomy. 
     Referring now to  FIG.  27   , there is shown a flow chart illustrating another method  650  for closing an opening in biological tissue using the suture guide system  300   c  shown in  FIG.  25   . 
     As set forth in the flow chart, i.e.,  FIG.  27   , and illustrated in  FIG.  28   , first and second ends  102   a ,  102   b  of suture  102  are first loaded into the distal ends of  369   a ,  369   b  of cannula shafts  368   a ,  368   b , respectively [ 651 ]. 
     Referring now to  FIG.  29 A , after the first and second ends  102   a ,  102   b  of suture  102  are loaded into the distal ends of  369   a ,  369   b  of cannula shafts  368   a ,  368   b , respectively [ 651 ], the first and second actuators  367   a ,  367   b , i.e., sliders  360   a ,  360   b , are positioned in initial retracted positions [ 652 ], whereby the first and second distal ends distal ends of  369   a ,  369   b  of cannula shafts  368 ,  368   b  are positioned proximate the tissue positioning sub-system  400   c.    
     As illustrated in  FIG.  29 A , when the first and second actuators  367   a ,  367   b  are in an initial retracted position, the first and second flexible hooked ends  374   a ,  374   b  of the first and second suture snares  370   a ,  370   b  are deflected under the first and second actuators  367   a ,  367   b , respectively. 
     Referring again to  FIG.  31 A , after the first and second actuators  367   a ,  367   b  are positioned in an initial retracted position [ 652 ] and an incision is made in the biological tissue (and, hence, structure), the elongated guide region  355  of suture guide system  300   c  is inserted into (and, preferably, through) the opening in the tissue structure provided by the incision [ 653 ]. In the method embodiment described herein, the biological tissue structure similarly comprises an abdominal tissue wall  12 . 
     After the elongated guide region  355  of suture guide system  300   c  is inserted into the tissue structure [ 653 ], the elongated guide region  355  is positioned in the biological tissue structure such that the exposed tissue positioning region  400   c  is disposed proximate to and engages a first portion of biological tissue  60   a  [ 654 ]. In this instance, the first portion of biological tissue  60   a  similarly comprises a portion of intra-abdominal tissue, more preferably, a portion of muscle/fascia and peritoneum layers  56 ,  58 . 
     Referring now to  FIG.  29 B , after the first portion of biological tissue  60   a  is engaged by the tissue positioning region  400 . [ 654 ], the first actuator  367   a  is advanced along the first guide slot  351   a  toward the distal end  354  of the elongated guide region  355  of suture guide system  300   c  [ 655 ]. According to the invention, when the first actuator  367   a  is advanced toward the distal end  354  of the suture guide system  300   c , the first cannula shaft  368   a  is inserted into and through the first portion of biological tissue  60   a  engaged to the tissue positioning region  400   c . The first flexible hooked end  374   a  of the first suture snare  370   a  is also no longer defected and transitions to an extended, relaxed state. 
     Referring now to  FIG.  29 C , after the first actuator  367   a  is advanced toward the distal end  354  of the elongated guide region  355  [ 655 ], the first actuator  367   a  is partially retracted toward the proximal end  352  of suture guide system  300   c  [ 656 ]. When the first actuator  367   a  is partially retracted, the first cannula shaft  368   a  is at least partially withdrawn from the first portion of biological tissue  60   a  and the suture  102  is engaged to and restrained by the first portion of biological tissue  60   a . The first suture end  102   a  is also positioned within the first suture capture member  372   a  of the first suture snare  370   a.    
     Referring now to  FIG.  31 A , after the first actuator  367   a  is partially retracted [ 656 ], the first actuator  367   a  is then fully retracted [ 657 ], whereby the first actuator  367   a  retracts the first suture snare  370   a  and, hence, first suture end  102   a  engaged thereto into the elongated guide region  355  of the suture guide housing  350 . 
     Referring now to  FIG.  31 B , after the first actuator  367   a  is fully retracted [ 657 ], the suture guide system  300   c  is rotated, preferably, rotated approximately 180°, whereby a contralateral second portion of biological tissue  60   b  is engaged by the tissue positioning region  400   c  of the suture guide sub-system  300   a  [ 658 ]. 
     After the suture guide system  300   c  is rotated [ 658 ], the second actuator  367   b  is advanced along the second guide slot  351   b  toward the distal end  354  of the elongated guide region  355  of suture guide system  300   c  [ 659 ]. According to the invention, when the second actuator  367   b  is advanced, the second cannula shaft  368   b  is similarly inserted into and through the second portion of biological tissue  60   b  engaged to the tissue positioning region  400   c . The second flexible hooked end  374   b  of the second suture snare  370   b  is also no longer defected and similarly transitions to an extended, relaxed state. 
     The second actuator  367   b  is then similarly partially retracted toward the proximal end  352  of the elongated guide region  355  of suture guide system  300   c  [ 660 ], whereby the second cannula shaft  368   b  is similarly partially withdrawn from the second portion of biological tissue  60   b . When the second actuator  367   b  is partially retracted, the second cannula shaft  368   b  is similarly withdrawn from the second portion of biological tissue  60   b  and the suture  102  is also engaged to and restrained by the second portion of biological tissue  60   b . The second suture end  102   b  is also positioned within the second suture capture member  372   b  of the second suture snare  370   b.    
     After the second actuator  367   b  is partially retracted [ 660 ], the second actuator  367   b  is then fully retracted [ 661 ], whereby the second actuator  367   b  similarly retracts the second suture snare  370   b  and, hence, second suture end  102   b  engaged thereto into the elongated guide region  355  of the suture guide housing  350 . 
     After the second actuator  367   b  is fully retracted [ 661 ], the suture guide system  300   c  is withdrawn from the biological tissue structure, e.g., abdominal wall  12 , with the first and second suture ends  102   a ,  102   b  ensnared by the first and second suture capture members  372   a ,  372   b , respectively [ 662 ]. 
     After the suture guide system  300   c  is withdrawn from the biological tissue structure [ 662 ], the first and second suture ends  102   a ,  102   b  are released from the first and second suture capture members  372   a ,  372   b  are tied together, whereby the opening in the tissue structure is closed, more preferably, ligated, fixated and closed [ 663 ]. 
     In some envisioned embodiments of the invention, the suture guide system  300   c  further comprises a suture loading component that is adapted to load a suture into the cannula shafts  368   a ,  368   b . In the noted embodiments, the suture  102  could run outside the housing  350  instead of within the housing  350 . 
     According to the invention, a further alternative suture guide system that can be employed to close biological tissue is disclosed in Applicant&#39;s U.S. Pat. No. 9,393,011, which is expressly incorporated herein in its entirety. 
     As will readily be appreciated by one having ordinary skill in the art, the present invention provides numerous advantages compared to prior art methods and systems for accessing biological tissue (and structures) and closing openings in biological tissue. Among the advantages are the following:
         The provision of tissue access and closure systems that can be readily employed to facilitate various laparoscopic surgical procedures in a simple and economical manner.   The provision of tissue access and closure systems that can be readily employed to access internal structures; particularly, intra-abdominal structures in a minimally invasive manner.   The provision of tissue access and closure systems that can be readily employed to effectively approximate, ligate, fixate and close biological tissue; particularly, laparoscopic ports or incisions in biological tissue.       

     Without departing from the spirit and scope of this invention, one of ordinary skill can make various changes and modifications to the invention to adapt it to various usages and conditions. As such, these changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.