Abstract:
An intervention is performed on a target anatomic structure of a patient body by first altering the configuration of the diaphragm through displacement or puncturing of the latter, in order to create a passageway leading into the thoracic cavity. An implement is introduced into the thoracic cavity through the passageway. The implement is then used while extending through the passageway to alter a biological tissue of the target structure or manipulate the latter. Optionally, a separating component having a peripheral wall encompassing a component channel is introduced into the passageway for receiving the implement and separating the latter from the non-target anatomic structure.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to a surgical apparatus and method for performing less-invasive surgical procedures, and more specifically, to a surgical apparatus and method for performing a surgical procedure on the beating heart, such as stabilizing a portion of a beating heart during a coronary artery revascularization, wherein said surgical procedure is performed through a percutaneous transabdominal approach.  
         BACKGROUND OF THE INVENTION  
         [0002]    Cardiac surgery, and more specifically traditional coronary artery bypass graft (CABG) surgery, has been performed since the 1970&#39;s on a regular basis with the advent of the cardio-pulmonary machine. In traditional CABG, the patient&#39;s heart is exposed by cutting through the patient&#39;s sternum and retracting the two halves of the ribcage. The heart is subsequently stopped while the blood continues to be pumped and oxygenated outside the body through extracorporeal circulation (ECC). The development of the cardio-pulmonary machine for ECC enables surgical interventions to take place on an arrested heart. This allows the surgeon to manipulate and operate on a perfectly still heart. As such, the arrested heart may be positioned to expose and provide the best access to the target artery requiring a bypass grafting.  
           [0003]    However, there are two main invasive aspects associated to traditional CABG—the sternotomy incision and the ECC. Even with the constant technological improvements achieved during the last twenty-five years, the advantages offered with ECC have been at times offset by the morbidity (complications) and mortality related to the ECC itself. ECC has been documented to produce some well-known complications. Adverse effects associated with its use continue to be discovered and as such, ECC represents one of the most invasive clinical aspect associated with traditional CABG surgery. The inflammatory response, as well as the systemic microembolisms generated by ECC, induce to some extent a dysfunctional state of the brain, lungs, and kidneys, which tends to increase with the aging of the patient. Furthermore, evidence suggests that when ECC can be avoided, the left ventricular function (pumping efficiency) of the heart is better preserved, thereby also reducing the risks of postoperative complications and the need for ventricular assist devices to wean the arrested heart back to normal function. In addition to being one of the most invasive aspects of traditional CABG, ECC is also responsible for a large percentage of the initial procedure cost of traditional CABG. If ECC-related complications develop, ECC is also responsible for the post-operative costs incurred to treat these complications.  
           [0004]    A median sternotomy, although less clinically-invasive than ECC, has the perception of being more invasive due to the surgical scaring that results from the surgery. A full median sternotomy may result in a temporary disturbance in the respiratory mechanism, an increased risk of operative shock or dehiscence, and re-operation surgery from bleeding complications. Moreover, prolonged exposure to air of the exposed mediastinum may lead to hypothermia, infection or compromise of the neuro-endocrine response. Patients with severe chronic obstructive pulmonary disease (COPD), severe emphysema or severe pulmonary insufficiency are therefore at a higher risk of developing complications when exposed to a sternotomy incision.  
           [0005]    Port access surgery, developed largely by Heartport Inc. of Redwood City, Calif., consists of replacing the full median sternotomy by a series of intercostal port incisions in the patient&#39;s chest, through which coronary artery revascularization is performed. However, the most invasive aspect, ECC, is retained in this type of surgery. The patient&#39;s heart is arrested by occluding the patient&#39;s aorta preferably between the coronary arteries and the brachiocephalic artery with an expandable balloon on the distal end of an endovascular catheter which may be introduced via a femoral artery. Cardioplegic fluid is then delivered to the patient&#39;s myocardium through a lumen in the same catheter or through a separate catheter positioned in the coronary sinus. A series of cannulae and catheters are usually employed to divert the patient&#39;s blood flow to the cardiopulmonary machine and to return the oxygenated blood to the circulatory system while the aorta remains occluded to avoid backflow into the heart chambers and surgical field. The port access approach most often also requires lung deflation in order to improve the access to remote territories of the heart, such as the posterior coronary territory. Unlike traditional CABG, the longitudinal axis and apex of the heart cannot be “verticalized” with respect to the surgical table and retracted chest cavity tending to facilitate access to the posterior territory. Performing port access surgery remotely through a number of small ports tends to be difficult, at times leading to unwanted tissue dissection that requires the conversion to a full sternotomy in order to complete the surgical procedure.  
           [0006]    In recent years, the drive for less-invasive and cost-effective surgical approaches and apparatus has placed emphasis on cardiac surgery as well. However, unlike other organ surgeries, gall bladder for instance, the beating motion of the heart tends to complicate the surgical intervention.  
           [0007]    In minimally invasive direct coronary artery bypass graft surgery (MIDCAB), ECC is avoided and coronary artery revascularization is performed directly on the beating heart with the help of a mechanical coronary artery stabilizer, through a mini-sternotomy or mini-thoracotomy incision. This surgical approach allows access to only one or two of the anterior arteries of the heart, most commonly the left anterior descending artery (LAD). Demographically, only 5-15% of the cardiac surgery population is afflicted with single vessel disease; the majority of cardiac patients (70%) suffer from triple vessel disease, whereby at least one artery on each of the anterior, inferior and posterior territories of the heart requires a bypass graft. As a result, this approach has also been referred to as “limited access bypass surgery”. Moreover, the MIDCAB thoracotomy incision to access the beating heart has been discovered to be more painful and less tolerated by patients than originally anticipated, especially in younger patients.  
           [0008]    More recently, the beating heart approach through a sternotomy incision has been adopted tending to facilitate positioning of the beating heart within the retracted chest cavity and tending to facilitate grafting of the difficult to access posterior arteries. Mechanical coronary artery stabilizers have been developed to immobilize a portion of the beating heart surface proximate to the target artery during the distal anastomosis phase of the surgery. A median sternotomy is desirable since it tends to allow the apex of the beating heart to clear the retracted ribcage as the heart&#39;s longitudinal axis is “verticalized” in order to expose the posterior coronary territory. In some patients, verticalization of a beating heart is not well tolerated and may lead to hemodynamic instability during the surgical procedure. At times, this unnatural “verticalized” orientation of the beating heart may be attained with some degree of atrial or ventricular distortion, and even some degree of valvular dysfunction and regurgitation. Moreover, although the beating heart approach achieves the elimination of the cardiopulmonary machine, the sternotomy incision with its associated complications is retained in this approach.  
           [0009]    Percutaneous transluminal angioplasty (PCTA) or Coronary Stenting are intraluminal surgical procedures which achieve coronary artery revascularization through the enlarging of restricted vessels by balloon angioplasty (PTCA) and in some cases also supplemented by the scaffolding effect of the tubular mesh stent. Sternotomy incisions and ECC are avoided since the entire procedure takes place through the patient&#39;s artery. However, the high incidence of restenosis associated with PTCA, and its generally low endorsement in the treatment of triple vessel disease does not make this procedure suitable to the majority of cardiac surgery patients that require coronary artery revascularization. Other emerging technologies, such as Transmyocardial Revascularization (TMR) or Percutaneous Myocardial Revascularization (PMR) are reserved for surgically non-reconstructible coronary artery disease.  
           [0010]    It would therefore be advantageous to have a surgical apparatus and associated surgical approach which maintains, as much as possible, the normal anatomic position and orientation of the heart during a surgical intervention. One aspect of the present invention aims to provide access to the posterior coronary territory of a beating heart during CABG surgery, without the need for a sternotomy incision, and while the longitudinal axis of the beating heart is maintained as much as possible in its natural, substantially-horizontal anatomic orientation. The combination of the beating heart approach with a surgical approach attempting to access all coronary territories without the need for either a sternotomy or thoracotomy incision would therefore offer distinct advantages in reducing the risk of complications and minimizing the surgical scaring normally associated with current CABG surgeries.  
           [0011]    A percutaneous incision in the abdominal region below the patient&#39;s ribcage, and the subsequent creation of a trans-abdominal, trans-diaphragmatic tunnel may provide a suitable surgical approach to attain the patient&#39;s thoracic cavity. The patient&#39;s heart and internal cardiac tissue may then be accessed by a variety of surgical instruments extending through an access cannula placed in said trans-abdominal tunnel and extending beyond an anatomic barrier, such as the patient&#39;s diaphragm. A number of surgical manipulations and interventions may then be performed by selected surgical instruments on the target tissue such as the patient&#39;s heart or other internal cardiac tissue. Internal cardiac tissue includes but is not limited to the pericardium, epicardium, myocardium, endocardium, apex of the heart, ascending and descending aorta, vena cava, coronary arteries and veins, internal thoracic arteries, pleurae, endothoracic fascia, and other like anatomic tissue.  
           [0012]    One aspect of the present invention describes a surgical apparatus that allows the manipulation and positioning of a beating heart within the patient&#39;s thoracic cavity, along with the deployment within the patient&#39;s thoracic cavity of coronary stabilizers that serve to immobilize a portion of said beating heart proximate to a target coronary artery, through a trans-abdominal tunnel. This aims to allow at least some surgical interventions associated with coronary artery revascularization to be performed without the invasiveness of ECC and without having to perform bone-cutting or bone splitting incisions such as sternotomy, intercostal thoracotomy with spreading of adjacent ribs, or other like surgical incisions. This tends to provide a closed chest surgical approach to perform cardiac interventions. The arteriotomy and distal coronary anastomosis, although may be performed through a number of intercostal ports not requiring the bone splitting or bone spreading incisions, are also preferably performed through the trans-abdominal, trans-diaphragmatic tunnel. In the present invention, the term “closed chest” will refer to surgical procedures which keep the patient&#39;s thoracic structure intact.  
           [0013]    It is therefore an object of the present invention to provide a surgical apparatus and method that enable coronary artery revascularization on the beating heart without the need for ECC, and without having to spread apart the patient&#39;s thoracic bone structure through a sternotomy, thoracotomy or other like incision.  
           [0014]    It is a another object of the present invention to provide a surgical apparatus and method that enable cardiac surgical interventions, not restricted to only beating heart CABG, to be performed without having to spread apart the patient&#39;s thoracic bone structure through a sternotomy, thoracotomy or other like incision.  
           [0015]    Some of the aspects of the present invention may also apply to other types of surgery, such as laparoscopic, endoscopic, or thoracoscopic surgery, whereby surgery is performed on target tissue contained within an internal body cavity that is accessed by surgical instrument disposed through an access cannula. Here the manipulation of surgical instruments during a surgical intervention performed through an access cannula may be better effectuated if said instruments are engaged with an internal joint within said cannula. Also it may be desirable in such surgical procedures to be able to secure said joint and maintain engaged instrument in a desired fixed position and orientation relative to the access cannula, at least for a part of the surgical procedure. The surgical procedure may also be further improved if the access cannula is also engaged with a movable joint connected to a stable surgical platform, whereby said joint may also be secured by a tightening means to maintain access cannula in a desired fixed position and orientation relative to patient and surgical table. The access cannula may also serve to introduce into the internal cavity surgical aids which may not engage target tissue during a surgical intervention, but help facilitate a surgery through their installation. For example, a camera lens or a fiber-optic bundle to provide light.  
           [0016]    It is a further object of the present invention to provide a surgical apparatus and method that tends to facilitate endoscopic surgery, more specifically endoscopic surgery where a surgical procedure is to be performed within an internal body cavity beyond an anatomic barrier, through the use of surgical instruments introduced therein through an access cannula.  
           [0017]    These and other objects of the present invention will become apparent from the description of the present invention and its preferred embodiments which follows.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention provides an access cannula with a substantially open proximal end and a substantially open distal end, and at least one substantially hollow passageway extending from said open proximal end to said open distal end. The outer surface of the access cannula is preferably engaged with at least one anatomic barrier. Target tissue is located in an internal body cavity or region downstream of an anatomic barrier and generally beyond the distal end of access cannula. The access cannula provides access, beyond at least one anatomic barrier, to a variety of surgical instruments which are able to extend beyond the distal end of access cannula. Some instruments will engage target tissue during at least a part of the surgical procedure they are intended for.  
           [0019]    Instruments are preferably engaged with access cannula through an internal joint which may provide a number of motion degrees of freedom to said instrument when they are engaged with access cannula. Surgical instruments may be demountably engaged with access cannula, or permanently engaged with respect to access cannula, or may even be engaged with access cannula via a cartridge in which they are disposed. Surgical instruments may be secured in a desired position and orientation relative to access cannula and relative to a target tissue through a tightening element.  
           [0020]    Proximal end of surgical instruments extend beyond proximal open end of access cannula, thereby allowing the surgeon to manipulate said proximal ends. Proximal manipulations on a proximal end of a surgical instrument, usually applied extracorporeally by the surgeon, are linked through an engagement with an internal joint to distal movements of a distal end of said instrument within an internal body cavity.  
           [0021]    The hollow passageway through an access cannula may be partitioned to create additional segregated passageways. Alternatively, substantially longitudinal access lumens extending generally from proximal end to the distal end may also be provided for engagement with surgical aids. Seal members may be provided across hollow passageways in order to maintain an internal body cavity, situated downstream of an anatomic barrier, at a different ambient condition than an extracorporeal region.  
           [0022]    Vision ports such as stereoscopic camera lenses, that transmit images to the surgeon so that closed chest interventions may be remotely performed, are deployed within an internal body cavity either through a transabdominal tunnel or through additional intercostal port incisions in the patient&#39;s chest. Carbon dioxide is used to displace abdominal organs during the deployment of surgical instruments used to create a transabdominal tunnel. Passages in the access cannula are also provided for the channeling of carbon dioxide gas into the pleural space.  
           [0023]    Access cannula may be manipulated and held by hand, but it is preferable to have it engaged with a stable support such as a surgical table. A surgical arm enables access cannula to be reoriented and repositioned relative to a surgical table and also the patient&#39;s body. Once a desired position is achieved, access cannula is secured into position.  
           [0024]    In performing a beating heart surgery, a variety of different surgical instruments may be engaged with access cannula, some are deployed alone while others may be deployed in combination. In one aspect of the invention aimed to perform coronary artery revascularization on a beating heart, a surgical apparatus is provided comprising an access cannula which is inserted through the diaphragm of the patient such that the distal end of cannula attains the pleural space. A heart manipulator, engaged with an internal joint inside the hollow passageway of access cannula engages the surface of the beating heart, preferably the apex, when said distal end of heart manipulator extends beyond the distal end of access cannula. Once a desired orientation and position of the beating heart is achieved, its position is secured relative to access cannula by an internal joint. A coronary stabilizer, also engaged with an internal joint inside the hollow passageway of the access cannula is then subsequently deployed. Coronary stabilizer is placed on a portion of the surface of a beating heart proximal to a target artery in need of anastomosis. The invention allows the surgeon to position a contact face on the surface of the beating heart and apply a gradual mechanical force until the portion of myocardium around the target artery is stabilized and rendered substantially motionless relative to cannula, while the rest of the heart continues to beat. The coronary stabilizer is subsequently secured. In approaching other vessels of the heart, as in multi-vessel CABG surgery, the access cannula may be rotated about its centerline relative to the heart and body in order to optimize the position of the heart manipulator and coronary stabilizer relative to the target heart tissue. The surgical apparatus aims to provide a way of accessing all territories of the heart by the deployment of an access cannula, and subsequent deployment of a heart manipulator and a coronary stabilizer relative to access cannula and to each other.  
           [0025]    Another aspect of the invention describes a surgical method in which the surgical apparatus may be used to perform coronary artery revascularization on the beating heart through an access cannula inserted through a transabdominal approach. This surgical method avoids the ECC and is less invasive for the patient. This surgical method also avoids the need for cutting the patient&#39;s ribcage, or spreading apart ribcage or removing part of patient&#39;s rib in order to access the patient&#39;s heart such as is the case with conventional CABG surgery or beating heart surgery performed through a sternotomy, thoracotomy, or other like incisions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    For better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of illustration and not of limitation to the accompanying drawings, which show an apparatus according to the preferred embodiments of the present invention, and in which:  
         [0027]    [0027]FIG. 1 is a perspective view of a first embodiment according to the present invention illustrating a surgical apparatus for performing beating heart CABG through a transabdominal tunnel;  
         [0028]    [0028]FIG. 2 is a perspective partial cutaway view of the patient illustrating the insertion of a laparoscopic cannula into the abdominal incision to access the pleural space, according to the present invention;  
         [0029]    [0029]FIGS. 3A and 3B are perspective views of the thoracic cavity illustrating the deployment of the access cannula of FIG. 1;  
         [0030]    [0030]FIG. 4 is a lateral section view of a diaphragm tissue retractor in a closed position engaged with the diaphragm according to an aspect of the present invention;  
         [0031]    [0031]FIGS. 5A and 5B are sectional views illustrating a method of engagement of the access cannula of FIG. 1 with an anatomic barrier;  
         [0032]    [0032]FIG. 6 is a partial lateral section view illustrating the mechanical arm of FIG. 1;  
         [0033]    [0033]FIG. 7 is a lateral cross section view illustrating the heart manipulator, coronary stabilizer, and access cannula of FIG. 1 engaged with the beating heart and the diaphragm;  
         [0034]    [0034]FIGS. 8A and 8B are end views illustrating several variants of access cannulae and variants of the internal joints according to the present invention;  
         [0035]    [0035]FIG. 9 is a lateral cross section view through the heart manipulator of FIG. 1;  
         [0036]    [0036]FIG. 10 is a perspective view of the coronary stabilizer of FIG. 1 illustrating the motion degrees of freedom;  
         [0037]    [0037]FIGS. 11A and 11B illustrate the cooperation of the access cannula, the heart manipulator and the coronary stabilizer of FIG. 1 in gaining access to the different coronary territories;  
         [0038]    [0038]FIG. 12 is a lateral section view of the thorax illustrating the deployment of a pericardium retraction device according to an aspect of the present invention;  
         [0039]    [0039]FIG. 13 is a lateral section view illustrating a variant of the diaphragm engagement means of the access cannula of FIG. 1;  
         [0040]    [0040]FIGS. 14A to  14 C illustrate variants of internal joints and seal means in the nature of a radial bellows according to an aspect of the present invention;  
         [0041]    [0041]FIGS. 15A to  15 D illustrate the positional relationship between the heart manipulator and the access cannula of FIG. 1;  
         [0042]    [0042]FIGS. 16A and 16B illustrate an access cannula with a variant seal means in the nature of compliant leaflets according to an aspect of the present invention;  
         [0043]    [0043]FIGS. 17A to  17 D illustrate the range of motion available to a variant of a heart manipulator engaged with an access cannula according to an aspect of the present invention;  
         [0044]    [0044]FIGS. 18A and 18B illustrate variants of a heart contacting member of the heart manipulator of FIG. 1;  
         [0045]    [0045]FIG. 19 is a schematic representation of the range of motion afforded to a surgical instrument within an access cannula according to the present invention;  
         [0046]    [0046]FIG. 20 is a perspective view of a second embodiment according to the present invention illustrating a surgical apparatus comprised of an access cannula, a heart manipulator, a coronary stabilizer, and a variety of endoscopic surgical instruments according to the present invention;.  
         [0047]    [0047]FIGS. 21A to  21 C illustrate a variant of an access cannula in the nature of a removable cartridge comprising internal joints and endoscopic surgical instruments, according to an aspect of the present invention;  
         [0048]    [0048]FIGS. 22A to  22 G illustrates a variety of endoscopic surgical instruments engaged with an access cannula and performing a variety of surgical procedures on a beating heart according to an aspect of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0049]    The features and principles of this invention may be applied, in whole or in part, to other types of cardiac surgery preferably performed through a closed chest approach, and where the patients internal cardiac tissue is attained through a trans-abdominal or trans-diaphragmatic tunnel. Also, the features and principles of this invention may also be applied, in whole or in part, to other endoscopic types of surgery which require access to a target tissue or target organ contained within an internal body cavity, beyond an anatomic barrier, through an access cannula engaged with said anatomic barrier. By way of illustration, the description of the embodiments and variants that follows herebelow will however focus on applying the features and principles of the present invention to cardiac surgery performed on a beating heart, and more specifically, to beating heart CABG surgery.  
         [0050]    In the present invention, the term “thoracic cavity” will generally refer to the volume enclosed by the inner surface of the patient&#39;s thorax and diaphragm. The term “pleural space” will generally refer to the volume of a thoracic cavity less the space occupied by the mediastinum and the lungs. The lungs normally occupy a large portion of the thoracic cavity. However, deflating a lung during a surgical procedure will augment the pleural space available, within which surgical instruments may be deployed.  
         [0051]    By way of a general overview and with reference to FIG. 2, a surgical incision is performed in the patient&#39;s abdomen (labelled AI), preferably in the left upper quadrant of the abdomen. A laparoscopic cannula  499  is subsequently inserted into the abdominal incision AI, and directed into the underlying extra-peritoneal space (labelled EPS), generally in the direction towards the patient&#39;s head. To facilitate the displacement of laparoscopic cannula  499  through the extra-peritoneal space, carbon dioxide gas (CO2) may be channeled through a hollow longitudinal passage in laparoscopic cannula  499  (not shown) and introduced into the extra-peritoneal space through its distal tip  4 . This tends to assist the dissection of the extra-peritoneal space and laterally displace the visceral organs (labelled VO) contained within the peritoneom (labelled PER) as the said cannula  499  is advanced within the patient&#39;s body. Proceeding in this manner, a sagittal tunnel is created spanning from the site of the abdominal incision to the patient&#39;s diaphragm, preferably at the left leaflet location. The diaphragm (labelled DG) constitutes an anatomic barrier that must be traversed in order eventually obtain access to the patient&#39;s heart. A guide wire  400  is then inserted through the center of laparoscopic cannula  499  and directed along said cannula  499  through the length of the sagittal tunnel. Once the guide wire  400  exits from the tip  4  of cannula  499 , it will be further advanced to pierce the diaphragm and attain the pleural space beyond the diaphragm. The laparoscopic cannula  499  is at this point retrieved from the patient&#39;s body leaving behind a guidewire that extends from outside the patient&#39;s body, into the abdominal incision, along the sagittal tunnel and beyond the pierced diaphragm into the pleural space (labelled PLS). An enlarging cannula  402  with conical tip  401  and hollow longitudinal passage (not shown) is then channeled over the guide wire  400 , through the abdominal incision, through the sagittal tunnel, to attain the diaphragm at the location where said guide wire  400  pierced through the diaphragm. Continuing to advance the enlarging cannula  402  over guide wire  400  will result in conical tip  401  progressively distending and enlarging the hole in the diaphragm initially pierced by guide wire  400 , up to a point when the cylindrical surface  403  of cannula  402  becomes engaged with the diaphragm (FIG. 4). Progressively enlarging a hole in body tissue by advancing a cannula configured with a conical tip is usually referred to in the art as a Seldinger Approach.  
         [0052]    According to one aspect of the present invention and with reference to FIG. 4, an anatomic barrier tissue retractor in the nature of diaphragm tissue retractor  40  is subsequently inserted over the enlarging cannula  402 . The diaphragm tissue retractor  40  is comprised of a substantially cylindrical hollow inner body  460 , a plurality of tissue-retracting petals  410 , a substantially cylindrical translating sleeve  440 , and a deployment lever  430  activated outside the patient&#39;s body. The proximal end of inner body  460  is configured with a handle portion  461  extending outwardly away from the longitudinal axis of said inner body  460 . The distal end of inner body  460  is configured with a plurality of circumferential slots  463 , which provide an opening into which a lug  412  of a retracting petal  410  may pivot when said petal  410  is deployed in the manner described below. Generally one lug  412  is required per petal  410 , and one slot  463  is required for each lug  412 .  
         [0053]    In their closed, non-deployed configuration, the plurality of tissue retracting petals  410  form a conical leading end profile  413  with a hollow substantially cylindrical tip  411 . Tip  411  is well-suited to being insertable and slidable over enlarging cannula  402 . Moreover, the conical profile  413  tends to facilitate the advancement of diaphragm tissue retractor  40  through the sagittal tunnel. When the diaphragm tissue retractor  40  is advanced through the patient&#39;s diaphragm, hollow tip  411  becomes inserted between the perimeter defining the pierced opening in the diaphragm and the cylindrical surface  403  of enlarging cannula  402 . Each petal  410  is rotatingly engaged with the distal end of inner body  460  through a hinge  420  disposed in lug  412 . Hinge  420  extends through lug  412  across its circumferential width, and also extends past said circumferential width into the lateral, faces defining circumferential slot  463  in inner body  460 . Petals  410 , along with their distal end which form a part of said cylindrical tip  411 , are then simultaneously deployed through the action of lever  430 . Lever  430  is engaged with handle  461  through a hinge  462 . A spring element (not shown) may be installed between lever  430  and handle  461  in order to maintain said lever and said handle apart. This minimizes the axial load applied to sleeve  440  thereby biasing tissue retractor  40  in its non-deployed, closed configuration. Deployment is achieved by depressing lever  430  sufficiently to overcome the spring load exerted from said spring element, thereby causing sleeve  440  to axially translate through a sliding fit  441  over the outer surface of inner body  460  and towards the distal end of retractor  40 . This entrains the engagement between cam-like surface  445  on translating sleeve  440  and cam-like profile  415  on lug  412  on each of the retracting petals  410 . As a result, the translation of sleeve  440  induces a radially inward force on each lug  412  and causes each petal to rotate about hinge  420 . The distal ends of retracting petals  410  which are engaged with the diaphragm will consequently be entrained to move outwardly away from the axis of inner body  460  and from one another, thereby retracting the diaphragm tissue in the process (FIG. 5A). The starting aperture in the diaphragm as illustrated in FIG. 4 is enlarged to a desired opening suitable for engagement with the distal end of an access cannula  10 .  
         [0054]    Unlike the Seldinger Approach, which generally requires a significant length of conical profile to gradually increase the opening in an anatomic barrier by progressive insertion of a conical tip cannula beyond said anatomic barrier, tissue retractor  40  tends to allow the significant enlargement of the diaphragm orifice with minimum risk of injury to the internal cardiac organs lying above and beyond the diaphragm. Significantly greater risk of injury would tend to result if a Seldinger Approach was used exclusively to create an aperture of the desired size in the diaphragm.  
         [0055]    Referring again to FIG. 5A, while the diaphragm tissue is maintained in its retracted state by tissue retractor  40 , an access cannula  10  is inserted through the center of hollow inner body  460  until its distal end  112  extends into the pleural space beyond the diaphragm. Distal end  112  is configured with an anatomic barrier engaging means in the nature of a permanent weir  130 . Permanent weir  130  is preferably rigid, but may also be made from a more flexible biocompatible polymeric material. Weir  130  preferably extends around the entire perimeter of access cannula  10 , and in this embodiment extends proudly above surface  113  of said cannula  10 . During installation of access cannula  10 , weir  130  is inserted past the end of retracting petals  410 . Deployment lever  430  is subsequently released, causing petals  410  to close slightly onto surface  113  and diaphragm tissue to contract slightly. Tissue retractor  40  is subsequently retrieved from the patient&#39;s body thereby leaving diaphragm tissue engaged with the distal end  112  of access cannula  10 , in a location upstream of permanent weir  130 .  
         [0056]    Carbon dioxide gas (CO2) may be introduced into the pleural space and thoracic cavity either through access cannula  10  (as will be described in greater detail below), or through a small intercostal trans-thoracic port incision. This trans-thoracic port incision does not necessitate the cutting or spreading apart of any of the patient&#39;s ribs which collectively form the thoracic structure (labelled TS). Pressurized CO2 tends to augment the pleural space and thoracic cavity by pushing down on the dome of the diaphragm. As such, the apex of the heart may be rotated towards the patient&#39;s feet into this augmented pleural space (FIG. 3A, 3B). A sealing member, described in greater detail below, may be incorporated within access cannula  10  to substantially maintain the CO2 pressure within the pleural space. When the diaphragm is engaged with the access cannula  10  in a manner as described above, weir  130  acts as an axial abutment face or buttress. The pressure loads on said cannula  10  will maintain it engaged with the diaphragm through the permanent weir  130 . Consequently, access cannula  10  may be slightly pushed out of the patient&#39;s body at the abdominal incision, leaving a shorter length of access cannula  10  engaged within the sagittal tunnel. Referring to FIGS. 3A and 3B, access cannula  10  may be configured with a demountable proximal extension tube  110 . Extension tube  110  serves to facilitate the installation of access cannula  10  into the body. Extension tube  110  also serves to facilitate the positioning and orientation of access cannula  10  relative to the patient&#39;s body. Referring to FIG. 3B, extension tube  110  is preferably detached from access cannula  10  once said cannula is engaged with securing platform  50 . This tends to improve the ergonomics of the extracorporeal work space. Extension tube  110  is connected to access cannula  10  through a threaded interface  111 . Alternatively, extension tube  110  may also be demountably connected to cannula  10  through a bayonet arrangement, a detented arrangement, a wedge fit or of any other like quick assembly interface.  
         [0057]    Alternatively, in surgeries where CO2 gas is not introduced into the pleural space, the diaphragm may also be mechanically pulled towards the patient&#39;s feet through the abutment face provided by weir  130  when cannula  10  is pulled by the surgeon. Those skilled in the art will appreciate that weir  130  may also be replaced by a circumferential groove, an expandable annular bladder, or any other like means which is capable of engaging the diaphragm through an axial abutment face, preferably configured at the distal end  112  of access cannula  10 .  
         [0058]    Access cannula  10  may be manually held in position by a surgical assistant during the surgical procedure. However, it is preferable to secure said cannula in a desired substantially stable position and orientation relative to a surgical table  3  or other like fixed stationary support. Referring to FIG. 3B, proximal end  114  of access cannula  10  is secured in place by a mechanical arm  50 . Mechanical arm  50  is comprised of a channel clamp  510 , an articulation rod assembly  540 , and a surgical table clamp  570  (FIGS. 5B and 6).  
         [0059]    A preferred embodiment of channel clamp  510  comprises a set of three annular discs  511 ,  512 ,  513  whose inner diameters  501 ,  502 ,  503  are preferably equivalent. Said inner diameters are only slightly larger than outer diameter  101  of access cannula  10  which extends over a longitudinal portion of its proximal end  114 . In a non-deployed state of clamp  510 , outer diameter  101  of said cannula  10  is free to slidingly rotate and axially translate relative to inner diameters  501 ,  502 , and  503 . Discs  511 ,  512 , and  513  are operatively engaged through annular shoulders  514  and  515  which extend laterally from side faces of disc  512  and engage annular groove  506  in disc  511  and groove  505  in disc  513 , respectively. Annular shoulders  514  and  515  are produced with the same eccentricity from the centerline of diameter  502 . Annular grooves  505  and  506  are produced with the same eccentricity as annular shoulders  515  and  514 . Outer discs  511  and  513  are engaged with disc  512  and permanently connected to each other, with matched eccentricities of annular grooves  506  and  505 , through a U-shaped block  516 . Said block  516  does not come into contact with the outer surface  507  of disc  512 . At one location along its outer surface  507 , disc  512  is configured with a lever  504  which extends radially away from said surface  507 . Preferably, said lever  504  sits diametrically opposite to U-block  516  when clamp  510  is in its non-deployed state. By moving lever  504  and rotating disc  512  relative to outer discs  511  and  513  will radially offset disc  512  relative to said discs  511  and  513  by virtue of the eccentric interface between annular grooves  505 ,  506  and annular shoulders  514 ,  515 . Consequently, the three diameter  501 ,  502 , and  503  will place the engaged length of outer diameter  101  in shear, thereby achieving a desired clamping action. Outer diameter  101  will be clamped between a circumferential sector of diameter  502  and diametrically opposite circumferential sectors of diameters  501 ,  503 .  
         [0060]    Block  516  is permanently attached to a support rod  517  that has a sphere  518  at the end opposite to block  516 . Nut  541  is inserted over rod  517  before it becomes permanently axially retained by sphere  518 , once said sphere is permanently mounted to rod  517 . Sphere  518  is brought into engagement with socket  550  on threaded end  551  of articulation rod  543  and socket surface  543  within nut  541  when said nut  541  is threaded onto articulation rod  543 . When nut  541  is not fully tightened to articulation rod  542 , channel clamp  510  is free to rotate and pivot about the center point of sphere  518  within the conical limits defined by the surface  542  of nut  541 .  
         [0061]    Articulation rod  543  is configured with another socket  560  at opposite threaded end  553 . Socket  560  and socket surface  552  within nut  562  are brought into engagement with socket  571  of surgical table clamp  570  when articulation rod  543  is threaded into said nut  562 . When articulation rod  543  is not fully tightened to nut  562 , articulation rod  543  is free to pivot about the center of sphere  571  within the conical limits defined by surface  563  of nut  562 . Sphere  571  is permanently attached to clamp block  572  via rod  573 . Nut  562  is inserted over rod  573  before it becomes permanently axially retained by sphere  571 , once said sphere is permanently mounted to rod  573 .  
         [0062]    The location of hole  561  in nut  562  is suitably selected to attempt to provide optimum positioning range for articulation rod assembly  540  and channel clamp  510  with respect to the patient. Clamp block  572  is secured to a surgical table  3  by tightening at least one screw  574  with the aid of a pivoted handle  575 .  
         [0063]    Those skilled in the art will appreciate that variations of mechanical arms are possible without departing from the spirit of the invention. Alternatively, channel clamp  510  and any other suitable portion of mechanical arm  50  may also be connected to a surgical robot instead of to a surgical table  3 .  
         [0064]    In summary, mechanical arm  50  is capable of securing access cannula  10  in a desired position and orientation with respect to the patient and to the surgical table  3 . Furthermore, mechanical arm  50  enable re-positioning and re-orientation of said cannula  10  during a surgical procedure, without having to disengage said cannula  10  from channel clamp  510 . With the channel clamp  510  and nut  541  not fully tightened, the access cannula is free to rotate about its longitudinal axis, translate along its longitudinal axis, and pivot about center of sphere  518 . These following motion degrees of freedom are referred to as herein as “coarse adjustment”.  
         [0065]    In one form of coarse re-adjustment, encountered in surgery such as multi-vessel CABG, it may be desirable to re-orient cannula  10  through a rotation about its longitudinal axis, while said cannula remains engaged with channel clamp  510  at its proximal end and with the diaphragm at its distal end. As described above, placing channel clamp  510  in its non-deployed state will easily allow said cannula to slidingly rotate about its centerline at its proximal end, while engaged in said clamp  510 . Referring to FIG. 13, distal end  112  of cannula  10  may be configured with a bearing arrangement  140  to facilitate the said rotation of cannula  10  relative to the engaged diaphragm tissue DG. Bearing arrangement  140  is comprised of an annular cuff  141  which is configured with an external annular groove  145  able to engage the pierced and retracted perimeter of an anatomic barrier, in this case diaphragm tissue DG. Annular cuff  141  is also configured with an internal annular ridge  146  which engages and cooperates with external annular groove  143  in surface  142  of cannula  10 . Outer surface  142  of cannula  10  and inner surface  144  of annular cuff  141  are preferably mating cylindrical surfaces allowing annular cuff  141  to be rotatingly engaged with cannula  10 . Cuff  141  is axially retained relative to cannula  10  through ridge  146 . A desired rotation of cannula  10  about its longitudinal axis will then result in a relative rotation between cuff  141  and cannula  10  while the diaphragm tissue remains fixedly engaged within groove  145  of cuff  141 . As such, by virtue of the bearing arrangement  140 , the said rotation of cannula  10  tends to limit the torsional load placed on the diaphragm and tends to limit the amount of circumferential slip between the diaphragm and cuff  141  along the engagement perimeter of diaphragm tissue with said cuff  141 .  
         [0066]    Outer surface  113  of access cannula  10  is substantially cylindrical and preferably smooth in order to avoid damage to internal body tissue during its insertion into and removal from patient&#39;s body. Referring to FIGS. 1 and 3B, the longitudinal length of cannula  10  is sufficient so that its proximal end  114  extends from patient&#39;s body at the site of the percutaneous surgical incision while its distal end  112  is engaged with an anatomic barrier. In this manner the proximal end  114  is exposed and may be engaged with channel clamp  510 . Alternatively, an access cannula  11  may be configured with a substantially conical outer surface  12 , where preferably the external diameter progressively diminishes from its proximal end  116  towards its distal end  115  (FIG. 16A). Other like tapered configurations are also possible where the overall external dimensions diminish from a proximal end to a distal end.  
         [0067]    Substantially open distal end  112  consists of at least one distal opening  115 . Substantially open proximal end  114  consists of at least one proximal opening  116 . Access cannula  10  is configured with at least one hollow passageway  120  that extends substantially lengthwise along said cannula, from proximal opening  116  to distal opening  115 .  
         [0068]    When access cannula  10  is deployed within the patient&#39;s body, and its distal end  112  is engaged with an anatomic barrier, proximal opening  116  lies upstream of said anatomic barrier, while distal opening  115  lies downstream of said anatomic barrier. As such, hollow passageway  120  thereby communicates a region generally upstream of said anatomic barrier with an internal body cavity containing target body tissue, generally downstream of said anatomic barrier, on which a surgical intervention is intended to be performed. For example, access cannula  10  may communicate an extracorporeal region (labelled ECR) upstream of the patient&#39;s diaphragm DG, with the patient&#39;s pleural space PLS downstream of said diaphragm DG. A surgical intervention may then be performed on internal cardiac tissue which becomes accessible through hollow passageway  120  of said cannula  10 .  
         [0069]    As illustrated in FIG. 5B, access cannula  10  is preferably configured to engage the diaphragm at a location close to its distal end  112  with an aim to minimize the protrusion of said distal end into the thoracic cavity. However, in certain surgeries it may be desirable to have an access cannula  10  which engages an anatomic barrier at a location closer to its proximal end  114 , even midway between said proximal and distal ends.  
         [0070]    In some current endoscopic surgeries, the distal end of an endoscopic surgical instrument is generally manipulated through its proximal handle portion which remains accessible to the surgeon while said endoscopic instrument is inserted into a laparoscopy cannula. Delicate surgical procedures tend to be difficult to master, primarily due to the large unsupported overhang that exists between distal end and proximal end that is grasped by the surgeon&#39;s hand. Often times, a compromised tactile sense also tends to result.  
         [0071]    Although it is also possible to introduce surgical instrument through access cannula  10  in a similar fashion to a laparoscopy cannula, according to one aspect of the present invention it is preferable to have a surgical instrument engaged with an internal joint  180  disposed within hollow passageway  120  of cannula  10 . Internal joint  180  acts as a lateral support member and serves to minimize the overhang between the proximal end and the distal end of a surgical instrument engaged therein. Internal joint  180  is free to move when engaged with a surgical instrument prior to being secured into a fixed position through a tightening member  181 . When said internal joint is secured, it may serve to retain a surgical instrument engaged therein in a fixed position and orientation relative to access cannula  10 . As will be explained further below, internal joint  180  may also act as a fulcrum member. By virtue of the fulcrum member, a surgeon input applied to a surgical instrument at its proximal end will be transferred to its distal end, whereby the resulting movement of the distal end may be of an equal magnitude, greater magnitude, or a lesser magnitude relative to said surgeon input.  
         [0072]    Referring to FIGS. 14A and 14B, at least one internal joint is provided within the at least one hollow passageway  120  in access cannula  10 . Internal joint  180  protrudes away from the internal surface of hollow passageway  120  so that it may become engaged with a portion of a surgical instrument. Internal joint  180  is comprised of a substantially spherical collet  182 , a yoke  186 , and a tightening member  181 . Said collet  182  is configured with a cylindrical bore  184  whose centerline coincides with the center of spherical collet  182 . Said collet  182  is configured with at least one split gap  183  extending from its outer spherical surface to inner cylindrical surface defining bore  184 . Said split gap  183  preferably extends throughout the entire longitudinal length of said bore  184 . Alternatively, collet  182  may be configured with a plurality of like split gaps as those skilled in the art will appreciate. Collet  182  is preferably made from a substantially elastic material.  
         [0073]    A surgical instrument may first be inserted into bore  184  of spherical collet  182 , and the resulting assembly thereof transversely installed into yoke  186 . In this respect, internal joint  180  is considered an “open-ended design” since it permits a surgical instrument to be transversely mounted into engagement with inner joint  180 . Alternatively, spherical collet  182  may first be engaged into yoke  186  and a surgical instrument subsequently installed axially through bore  184  thereof. Yoke  186  is configured with a spherical seat  185 . Extension rod  189  is provided with an anti-rotation flat  187  which cooperate with opening  118  when said rod is inserted through said opening. Tightening member  181  engages with thread  188  on the distal end of extension rod  189 .  
         [0074]    Collet  182  simultaneously cooperates with socket surface  119  of access cannula  10  and spherical seat  185  of yoke  186 , when internal joint is fully assembled. Applying a torque to tightening member  181  will entrain seat  185  into light contact with spherical collet  182 , and spherical collet  182  into light contact with socket surface  119 . At this point, a surgeon manipulation (input) applied to the proximal end of surgical instrument will be easily sufficient to set into relative motion spherical collet  182  relative to socket surfaces  185  and  119  (free state). Applying a greater torque to tightening member  181  will augment the friction between external surface of collet  182  and said spherical surfaces  185  and  119 , thereby providing a greater resistance to the surgeon input (constrained state). Increasing the tightening torque still further will compress spherical collet  182 . The resulting compression force is transferred to the portion of a surgical instrument engaged within bore  184  as a clamping load by virtue of split gap  183 , thereby securing the entire assembly of components defining internal joint  180  (locked state). Relieving the tightening torque on tightening member  181  will relieve said clamping load on said surgical instrument and relieve the friction between socket surfaces  119 ,  185  and spherical collet  182 . The internal joint  180  resumes its free state, aided in part by the elastic nature of collet  182 . At this point, said surgical instrument is once again free to be re-positioned and reoriented with respect to access cannula  10  through internal joint  180 .  
         [0075]    The portion of a surgical instrument engaged within bore  184  is preferably of circular cross-section. The internal joint  180  provides the following motion degrees of freedom when engaged in “free state” with a surgical instrument: translation of said surgical instrument along centerline of bore  184 , rotation of said surgical instrument about centerline of bore  184 , pivoting of said surgical instrument about a longitudinal axis through extension rod  189 , pivoting of said surgical instrument about an axis perpendicular to longitudinal axis through extension rod  189  and simultaneously perpendicular to centerline of bore  184 . Open-ended internal joint  180  allows  4  motion degrees of freedom and may be secured through tightening member  181  which is situated on the exterior of access cannula  10 . These motion degrees of freedom between a surgical instrument and access cannula  10  are referred to herein as “fine adjustments”. Alternatively, a surgical instrument with one or more integral spherical bosses along its longitudinal axis may be inserted into internal joint  180  in place of spherical collet  182 .  
         [0076]    Open-ended internal joints permit the substitution of surgical instruments engaged with said joints, without having to disrupt the coarse adjustment of the surgical set-up.  
         [0077]    Other variations of internal joints may be configured as those skilled in the art will appreciate, some with fewer motion degrees of freedom. For instance, a joint that only allows translation along the longitudinal axis of a surgical instrument, a joint that only allows rotation of a surgical instrument about its centerline, a joint that only allows pivoting about one axis, and any combination thereof represent potential embodiments.  
         [0078]    A close-ended variant of the internal joint  180  is illustrated in FIGS. 14A and 14B. Close-ended joint  150  is preferably employed to engage surgical instruments that form an integral permanent assembly with an access cannula. Alternatively, in non-permanent assemblies, close-ended joints may also be employed with surgical instruments having cross-sectional dimensions inferior to bore  151 , which are therefore capable of being axially inserted through said bore.  
         [0079]    [0079]FIG. 8A illustrates another variant of an open-ended internal joint  170 . Internal joint  170  is comprised of two jaws  174 ,  175  which are pivotingly engaged through hinge member  173 . Said jaws cooperate to clamp a surgical instrument at open-ended bore  176  when wedge  172  is retracted through hollow boss  171  through its connection to threaded rod  177 . Applying a tightening torque to tightening member  181  will entrain threaded end  177  to move axially through hollow boss  171 . Prior to applying a securing torque to said member  181 , jaws  174 , 175  are free to rotate about the centerline of threaded rod  177 . Inner joint  170  provides the following motion degrees of freedom: translation of a surgical instrument along the longitudinal axis of bore  176 , rotation of a surgical instrument about centerline of bore  176 , and rotation about centerline axis of rod  177 .  
         [0080]    Another close-ended, multi-degree of freedom variant of an internal joint is illustrated in FIG. 8B. Internal joint  190  is comprised of two C-shaped jaws  191  and an articulation cylinder  194 . Each jaw  191  has a threaded rod  197  extending along its longitudinal axis. Each jaw  191  has a substantially hemi-cylindrical surface  193  defined by an axis perpendicular to its longitudinal axis. Each jaw has a lateral member  165 , offset from longitudinal axis of said jaw, connecting threaded rod  197  to surface  193 . When jaws  193  are assembled with articulation cylinder  194 , threaded rods  197  extend in opposing directions through a common centerline, each of surfaces  193  lie diametrically opposed, and each of lateral members  165  are laterally opposed. Articulation cylinder  194  is laterally trapped between said lateral members  165  and radially engaged with each of the hemi-cylindrical surfaces  193 . A cylindrical bore  195 , perpendicular to the centerline of cylindrical outer surface of articulation cylinder  194 , is provided to receive a portion of a surgical instrument axially inserted therein. The inner surface of cylindrical bore  195  is interrupted by at least one substantially longitudinal split  196 .  
         [0081]    When assembled jaws  193  are assembled, outboard surfaces of lateral members  165  form a partial interrupted cylinder whose centerline is coincident with centerline of threaded rods  197 . The assembly comprised of jaws  191  and articulation cylinder  194  is transversally inserted into bore  192  of access cannula  10 . Threaded rod  197  of one of the jaws  191  is sufficiently threaded into boss  199  of cannula  10  such that centerline of bore  195  is substantially aligned with longitudinal axis of access cannula  10 . At least a portion of said cylinder formed by outboard surfaces of lateral members  165  cooperates with bore  192  as internal joint  190  rotates within said bore  192 . As internal joint  190  rotates within bore  192  threaded rod threads or unthreads itself into boss  199 . Said bore  192  is mostly open towards the center of access cannula  10  providing substantially unrestricted motion to a surgical instrument engaged in bore  195  of articulation cylinder  194 . Washer  198  is inserted between access cannula  10  and tightening member  181 . A tightening torque applied to tightening member  181 , will entrain into contact said hemi-cylindrical surfaces  193  with outer diameter of articulation cylinder  194 . A substantially diametrical clamping load will be applied to outer diameter of articulation cylinder  194 . The resulting compression force is transferred to the portion of a surgical instrument engaged within bore  195  by virtue of split  196 , thereby securing the entire assembly of components defining internal joint  190 .  
         [0082]    Internal joint  190  allows the following motion degrees of freedom: translation of a surgical instrument along centerline of bore  195 , rotation of a surgical instrument about centerline of bore  195 , pivoting of a surgical instrument about centerline through bore  192 , pivoting of a surgical instrument about an axis perpendicular to centerline through bore  192  and simultaneously perpendicular to centerline of bore  195 . Once the desired position and orientation of a surgical instrument is achieved, this fine adjustment is secured through tightening member  181  situated on the exterior of access cannula  10 .  
         [0083]    Internal joints  150 ,  170 ,  180 , and  190  may engage the particular surgical instruments according to the present invention, and also existing endoscopic instruments, laparoscopic instruments, cardiac surgery instruments and other like instruments.  
         [0084]    Internal joint  180  acts as a fulcrum point allowing the movement at the proximal end of a surgical instrument (surgeon input) to be transferred through internal joint  180  to a corresponding linked movement at the distal end of said surgical instrument. For the purposes of illustration, FIG. 20 schematically represents access cannula  10  as a cylinder. An internal joint is located within access cannula  10  at a distance X from proximal open end  116  and at a distance Y from the center line of access cannula  10 . A surgical instrument is schematically represented as a line (labelled “SI”). PS 1  represents the surface area within which a surgeon may position a proximal point P of a surgical instrument, when said point P is held at a fixed distance from the center of the internal joint. When point P is held at a closer distance from the center of internal joint, PS 2  is generated. DS 1  and DS 2  represent the surface areas within which the distal point D of a surgical instrument is maintained during proximal manipulations of point P within PS 1  and PS 2 , respectively. The size and geometry of proximal surfaces PS 1  and PS 2  and of distal surfaces DS 1  and DS 2  are a function of the specific geometry of access cannula  10 , the number of motion degrees of freedom offered by the internal joint, the range of motion of said offered motion degrees of freedom, the length of surgical instrument SI, and the distance between proximal point P on surgical instrument SI and internal joint. If a surgeon&#39;s input is applied to proximal point P and is limited to the confines of proximal surface PS 1 , distal point D will then be limited to the confines of distal surface DS 1 . As illustrated in FIG. 20, since proximal surface PS 1  is larger than corresponding distal surface DS 1 , a surgeon input applied at point P will result in a scaled down output at point D. Alternatively, if a surgeon&#39;s input is applied to proximal point P and is limited to the confines of proximal surface PS 2 , distal point D will then be limited to the confines of distal surface DS 2 . Since proximal surface PS 2  is smaller than distal surface DS 2 , a surgeon input applied at point P will result in a scaled up output at point D. Therefore, a surgeon input applied extracorporeally to a proximal end of a surgical instrument will entrain a linked movement of a distal end within an internal body cavity, downstream of an anatomic barrier by virtue of an internal joint.  
         [0085]    Hollow passageway  120  may be partitioned to define at least one other hollow passageway extending from proximal open end  116  to distal open end  115 . Two such hollow passageways  121 ,  122  are illustrated in FIG. 8A. At least one such passageway will be configured with an internal joint such as  150 ,  170   180 ,  190  or other like joint or variant thereof. In other surgical set-ups, it may be preferable to have at least one internal joint in each of the said hollow passage ways  121 ,  122 . The relative cross-sectional areas and cross-sectional geometries of partitioned hollow passageways may be tailored for the specific surgical instrument said passageway will be engaged with, or the specific surgical procedure that will take place in said passageway. In general, a hollow passageway is intended to be engaged with a surgical instrument. In configurations of access cannulas comprising more than one internal joint, said internal joints may each be disposed at a different location along the longitudinal axis of said cannula, and each be disposed at a different angular orientation relative center of longitudinal axis.  
         [0086]    In addition to hollow passageways, access cannula  10  may be configured with one or more access lumens  125  (FIGS. 8A, 8B,  14 A). Access lumens provide a substantially confined channel into which a surgical aid, fluid, or gas may be engaged or introduced.  
         [0087]    Each access lumen may serve a designated purpose during at least a part of a surgical procedure or may be specifically designed to engage a particular surgical aid for the duration of the surgical process. An access lumen may be integrally produced with access cannula  10  as a cored passage in the fabrication process. Alternatively, an access lumen may be formed from a channel member which is subsequently fastened to access cannula  10 , preferably within one of its hollow passageways. Access lumen may be fastened in a demountable or permanent manner to said access cannula  10 . Access lumens have at least one entry point  126  and at least one exit point  127 . Generally, access lumens extend from proximal open end  116  to distal open end  115  of cannula  10 . However, they may extend for only a part of the longitudinal length of cannula  10 . In either case, entry point  126  is generally located upstream of anatomic barrier and  127  is generally located downstream of anatomic barrier. This provides a communicative channel from a region upstream of said anatomic barrier (most often the extracorporeal space ECS) to an internal body cavity such as the pleural space PLS.  
         [0088]    In another variant, an access lumen may extend for only a part of the longitudinal length of cannula  10 , where entry point  126  and exit point  127  are either both upstream of anatomic barrier or both downstream of an anatomic barrier.  
         [0089]    In another variant, an access lumen  129  is configured with an exit point  127  leading into the at least one hollow passageway of access cannula  10  (FIG. 16A).  
         [0090]    In another variant, access lumen does not longitudinally along length of access cannula  10 , but may be of a helical configuration along the surface of hollow passageway  120 .  
         [0091]    In yet another variant, access lumen  128  may be configured with a circumferential segment acting as a manifold for a plurality of exit holes  127  (FIGS. 16A, 16B). This configuration may be preferable for introducing a surgical gas such as CO2 into the pleural space.  
         [0092]    Designated access lumens may be provided for engaging following surgical aids, or channeling the following fluids or gases: a malleable arm with small atraumatic clip at distal end thereof, a fiber optic bundle for illumination of surgical site, a surgical camera lens, CO2 pressurized gas, saline solution, pharmacological agents, a suction line, a catheter, a cannula, a laser probe, a doppler ultrasonography probe, a sensor, or any other like surgical aid, fluid or gas.  
         [0093]    A visioning system may be housed in an access lumen to allow the surgeon to vision the substantially closed pleural space (or thoracic cavity) during the surgical procedure performed therein. A visioning system is preferably comprised of stereoscopic camera lenses. In another variant, only some of the components of the vision system may be provided in an access lumen while other complimentary components may access the substantially closed thoracic cavity through intercostal access ports. Also in this manner separate vision cameras may be configured, one in an access lumen of access cannula  10 , another in an intercostal port incision, thereby allowing the surgical procedure within the thoracic cavity to be visioned through one or more different visual perspective.  
         [0094]    Access cannula  10  may be configured with a combination of internal joints, partitioned hollow passageways, and a number of access lumens. For instance, FIG. 8A illustrates a partitioned access cannula  10  with one open-ended internal joint  170 , two hollow passageways  121 ,  122  and two access lumens  125 . FIG. 8B illustrates a partitioned access cannula  10 , with one close-ended internal joint  190 , two hollow passageways  121 , 122 , and a plurality of access lumens  125 . FIG. 14A illustrates a partitioned access cannula  10  with a plurality of close-ended internal joints  150  and a plurality of open-ended joints  180 , two hollow passageways  121 , 122  and two access lumens  125 . Other combinations are also possible.  
         [0095]    Access cannula  10  may be configured with a provision for a sealable hollow passageway. A seal member  70  may be provided to span in a substantially transverse manner across a hollow passageway. Seal member  70  will preferably span across hollow passageway at a location between proximal open end  116  and distal open end  115  of said cannula  10 . Seal member  70  may also span across proximal open end  116  or distal open end  115 .  
         [0096]    Seal member  70  provides a substantial seal and substantially confines the ambient conditions present within the internal body cavity and within a hollow passageway downstream of said seal member, from the ambient conditions present in the hollow passageway upstream of said seal member and externally beyond the proximal open end  116  of said access cannula  10 . For instance, in surgeries where CO2 gas will be introduced into the pleural space PLS, the pressurized volume present within the pleural space and within a hollow passageway of access cannula  10  downstream of seal member  70  is substantially confined from the extracorporeal ambient conditions present upstream of said seal member. Evidently, to maintain said pressurized volume all hollow passageways must be provided with a seal member  70 , and all access lumens must also be substantially sealed either with a plug member engaged at entry point  126  or exit point  127 , or by the obstruction created by a surgical aid engaged within said access lumen, or by a seal member similar to seal member  70 .  
         [0097]    Seal member  70  may also be used to shield a portion of a hollow passageway and internal joints located upstream of said seal member from blood and other like body fluids present within the internal body cavity and downstream of said seal member. In a partitioned access cannula, a seal member may be provided in just one of the hollow passageways, or in all said passageways.  
         [0098]    [0098]FIG. 7 illustrates a conformable elastic seal membrane  701 . Seal membrane  701  is provided with one or more sealable ports in the nature of elastic nipple  702  through which a variety of surgical instruments may be easily inserted either before or during surgery. Elastic membrane  701  and nipple  702  will conform to suit the angle in which the shaft portion of a surgical instrument will be oriented within said nipple. This tends to provide substantially unconstrained motion of the surgical instrument within access cannula  10 . Further, elastic nipple  702  provides a compliant through-passage that stretches and shrinks to accommodate surgical instruments with different dimensions. Elastic nipple  702  is biased towards a closed, sealed position wherein said variable size through-passage is not engaged with a surgical instrument. Said nipple  702  is movable to an open, sealed position by virtue of inserting a surgical instrument therethrough. As such, elastic nipples  702  provide a substantial seal in both closed and open position.  
         [0099]    [0099]FIGS. 14B and 14C illustrate a conformable, elastic bellows-type seal  730 . Seal  730  is comprised of a plurality of elastic nipples  732 . Nipples  732  are self-energizing in that a pressure gradient will keep nipple closed and substantially non-flowing when surgical instrument is not engaged therein. When a surgical instrument is inserted in said nipple  732 , the self-energizing effect will keep nipple perimeter  733  in contact with surgical instrument. Pressure gradient for self-energizing effect requires the pressure downstream of nipple perimeter in region  734  to be greater than pressure upstream of seal in region  735 . As illustrated, seal  730  is self-energizing when pressurized CO2 is introduced into the pleural space. Seal  730  may be reversed to cater for opposite pressure gradients. Nipple  732  provides a substantial seal.  
         [0100]    Seal  730  is configured with a plurality of substantially concentric annular folds  731  originating from the center of each nipple  732 . Said plurality of annular folds  731  act as a radial bellows. A displacement of nipple  732  entrained by a movement of a surgical instrument relative to cannula  10 , will compress annular folds  731  in the direction of said displacement of nipple  732 . By virtue of its elastic material properties and its radial bellows configuration, seal  730  tends to allow substantially unconstrained motion of a surgical instrument within access cannula  10 .  
         [0101]    [0101]FIGS. 16A and 16B illustrate an elastic membrane-type seal  720  provided with one or more sealable ports in the nature of a plurality of overlapping leaflets  724  through which a variety of surgical instruments may be inserted. Said leaflets  724  are biased in a closed, not deflected orientation  721  thereby providing a substantial seal. When instrument is inserted through said sealable port, leaflets  724  are deflected  722  but remain in substantial contact with the shaft portion  723  of a surgical instrument. As such, leaflets  724  provide a substantial seal in both closed and deflected position. Leaflets will engage with shaft portion  723  to a varying extent depending on the orientation of said shaft portion  723  through said leaflets  724 . All leaflets will be engaged to at least some extent, throughout the complete range of orientations said shaft portion  723  is capable of assuming in order to maintain a substantial seal throughout said range. By virtue of its elastic material properties and its leaflet configuration, seal  720  tends to allow substantially unconstrained motion of a surgical instrument within access cannula  10 .  
         [0102]    By way of a general overview, FIG. 1 illustrates a surgical apparatus according to a first embodiment of the present invention. The surgical apparatus is comprised of a surgical arm  50 , an access cannula  10 , a heart manipulator  20 , and a coronary stabilizer  30 . Thoracoscopic surgical instruments  60  are provided with which the invention may be used. Said instruments  60  are deployed intercostally and tend to not require spreading of the patient&#39;s ribcage. Access cannula  10  is preferably deployed and engaged with the patient&#39;s diaphragm through diaphragm tissue retractor  40  in a manner described above.  
         [0103]    Referring to FIG. 7, heart manipulator  20  and coronary stabilizer  30  are preferably engaged with access cannula  10  through an internal joint  190  (or alternatively  150 ,  170 , or  180 ), in a manner already described with general reference to a surgical instrument.  
         [0104]    Once the coarse adjustment has been performed and access cannula  10  has been secured to channel clamp  510  of surgical arm  50  in the desired position and orientation relative to the patient&#39;s body, the heart manipulator  20  is preferably deployed first.  
         [0105]    Heart manipulator  20  engages a portion of the surface of a beating heart, preferably in the vicinity of the apex, through a negative pressure suction force. Said manipulator  20  serves to position and orient the patient&#39;s heart within the thoracic cavity. While it is engaged with the apex of the patient&#39;s heart, heart manipulator  20  may be secured through internal joint  190  in a desired position and orientation relative to access cannula  10  (fine adjustment), thereby also securing a position and orientation of the patient&#39;s heart relative to said access cannula  10 .  
         [0106]    Heart manipulator  20  is comprised of a hollow shaft member  220 , a heart contacting member  200  and a handle  240 . Shaft member  220  is preferably cylindrical in cross-section and hollow thereby configuring conduit  223  along its entire length. Shaft member  220  is engaged at its distal open end  226  with heart contacting member  200  and at its proximal open end  224  with a negative pressure source  227  through barb fitting  221 . Conduit  223  communicates negative pressure suction to the heart contact member  200  through its connection with a negative pressure source at barb fitting  221 . Heart manipulator  20  is manipulated by surgeon through handle  240  which extends beyond proximal open end  116  into extracorporeal space once heart manipulator is engaged in internal joint  190 . Handle  240  is preferably detachable through a sliding fit between outer surface  225  and bore  245  in said handle. This sliding fit allows said handle to be positioned at a desired location along shaft member  220 . When detachable handle  240  is removed from heart manipulator  20 , shaft member  220  may be axially inserted into a close-ended internal joint such as  190  prior to deploying access cannula  10  into engagement with diaphragm. Alternatively, heart manipulator  20  may be transversely engaged into an open-ended internal joint such as  180 ,  170  even after the access cannula  10  has been engaged with the diaphragm.  
         [0107]    Heart contacting member  200  is comprised of a substantially conical elastic sheath  204 , detachably mounted to shaft member  220  through a barb fitting interface formed by mating members  202  and  222 . Said sheath  204  may be produced from any suitable polymeric material approved for surgical use. Sheath  204  may be designed to have variable elastic properties by virtue of its variable thickness or by virtue of its variable composition during fabrication. Reinforcement fibers or structural ribs  201  may also be used in the fabrication of sheath  204  to bias its elasticity along certain axes. This is especially beneficial where the shaft member  220  is rigid, whereby elastic sheath  204  acts as a buffer in elastic gradient between said rigid member  220  and substantially non-rigid heart surface or non-structural membrane-like pericardium tissue if said heart manipulator is engaged with pericardium tissue. This buffer in elastic gradient may encourage the said heart surface or said pericardium tissue to remain in compliant contact with tissue-engaging perimeter  205  of said sheath.  
         [0108]    The open area perimeter  205  is configured with a tapered and beveled terminal edge in the nature of a deformable skirt  203 . This deformable skirt  203  achieves a substantially compliant seal perimeter at tissue-engaging perimeter  205 , capable of engaging the surface of the heart or pericardium tissue throughout a range of spatial orientations which the said heart or said pericardium tissue may assume relative to shaft member  220 . The deformable skirt  203  provides readjustment of the substantially planar surface formed by tissue-engaging perimeter  205  depending on the direction of application of tensile retraction loads applied to and reacted by the said heart or said pericardium tissue. A tensile retraction load applied to said heart or said pericardium tissue in a direction substantially parallel to the axis of shaft member  220  distorts the beveled edge of deformable skirt  203  equally around the tissue-engaging perimeter  205 , in an inward direction towards the center of said tissue-engaging perimeter  205 . If a tensile retraction load is applied to said heart or said pericardium tissue in a skewed direction relative to the axis of shaft member  220 , the beveled edge of skirt  203  will distort unevenly around the tissue-engaging perimeter  205  in a fashion that the substantially planar surface formed by tissue-engaging perimeter  205  is now oriented substantially perpendicular to the direction of application of said manipulation force or substantially perpendicular to the heart reaction force to imposed retraction loads.  
         [0109]    Alternatively, heart manipulator may be comprised of a plurality of conical elastic sheaths  204  configured in a manifold assembly and connected to a common hollow shaft member.  
         [0110]    Alternatively, a heart contact member comprising a substantially conical non-flowing static suction cup made from a flexible polymeric material may be utilized.  
         [0111]    Referring now to FIGS. 15A to  15 D, a portion of a beating heart containing the apex is engaged with heart contact member  200  and is schematically represented as APX. For the purposes of illustration, the different surfaces of the beating heart are identified by four arbitrary markers: “A” marks a point on the anterior surface of the heart; “R” marks a point on the right lateral surface of the heart; “P” marks a point on the posterior surface of the heart; and “L” marks a point on the left lateral side surface of the heart. Access cannula  10  is schematically illustrated as a cylinder in end view. For the purposes of illustration, three arbitrary markers “X”, “Y”, “Z” are identified on the perimeter of access cannula  10 . Heart manipulator  20 , and more specifically heart contact member  200  is represented by its tissue-engaging perimeter  205 . Internal joint  180  is reserved for coronary stabilizer  30  (not shown). Heart manipulator  20  is engaged in a similar internal joint (not shown), which for the purposes of this illustration is disposed diametrically opposite to said internal joint  180  about the centerline of access cannula  10 .  
         [0112]    [0112]FIG. 15A illustrates access cannula  10  secured in a desired position and orientation relative to surgical arm  50  (coarse adjustment), where internal joint  180  is located at top dead center (looking into cannula  10 ). When the beating heart is engaged with heart contact member  200 , and the heart manipulator  20  is engaged in internal joint  180 , said internal joint in its free state will allow the center of the heart contact member (labelled “CX” in FIG. 9) to be positionable anywhere within surface area AHC (area within circle labelled AHC). The size and shape of AHC is here only schematically represented as a circular area. AHC generally increases in size and its shape may vary as the distance from point CX to the center of spherical collet  182  of internal joint  180  increases. This is representative of a heart contacting member  200  being extended further into the pleural space PLS beyond the distal opening  115 . Now if this variable AHC area is integrated over the range that said heart contacting member  200  is capable of extending beyond the distal opening  115 , a volume results within which point CX may be positionable. The actual size and shape of AHC (and the resulting said volume) is a function of many parameters. Among these: the specific geometry of an access cannula, the number of motion degrees of freedom offered by a design of an internal joint, the range of motion of said offered motion degrees of freedom, and the distance between point CX and said internal joint. As a result of the foregoing, the apex of a beating heart when engaged with heart contacting member  200 , may also be positionable within a considerable volume.  
         [0113]    As illustrated in FIG. 15B, when access cannula  10  is re-oriented within channel clamp  510  through a 90 degree counterclockwise rotation about its centerline, surface area AHC orbits around the centerline of access cannula  10  while rotating 90 degrees counterclockwise. Nominal orbit trajectory is identified as ORB. The beating heart, represented by APX, orbits relative to the centerline of access cannula  10  but does not rotate. During this coarse readjustment, internal joint  180  is in its free state such that shaft member  220  is free to rotate about its centerline while tissue-engaging perimeter  205  remains engaged with said beating heart. By rotating access cannula  10  in the manner just described, all surfaces of the heart are generally accessible by coronary stabilizer  30  which may be deployed through the portion of hollow passageway  124  not occupied by heart manipulator  20 . FIG. 15A illustrates the surgical set-up well suited to access the anterior surface of a beating heart; FIG. 15B a surgical set-up well suited to access the right lateral surface of a beating heart, FIG. 15C a surgical set-up well suited to access the posterior surface of a heart, and FIG. 15D a surgical set-up well suited to access the left lateral surface of a beating heart.  
         [0114]    Referring to FIG. 10, the coronary stabilizer  30  is comprised of three main subassemblies: a proximal extracorporeal control section  380 ; a distal heart-contacting section  300  deployed within the thoracic cavity; and a connector section  390  for transmitting a surgeon input from said control section to said heart-contacting section.  
         [0115]    The control section  380  comprises a securing bolt  385 , a multi-socket cradle  389 , an annular brace  387 , an first adjustment dial  371 , and a second adjustment dial  331 . Cradle  389  is configured with three lobes  388 , only two of which are visible in FIG. 10. Each lobe  388  is configured with a spherical socket (not shown) that engages a spherical end (not shown) disposed on each of the three articulation transmission cables  340 . Said spherical ends may be permanently engaged with said spherical sockets in cradle  389  by flaring the socket perimeter around the spherical end. Alternatively, said spherical ends may be demountably engaged with said spherical sockets by virtue of a “snap in” design. Inner rod  386  is configured with three longitudinal channels  384  that each serve to house one of the transmission cables  340 .  
         [0116]    The cradle  389  is also configured with a central spherical socket (not shown) to engage and cooperate with a substantially spherical end (not shown) on the proximal extremity of inner rod  386 . The perimeter which defines the opening of said central spherical socket is locally flared a three locations to create a perimeter with three flared edges. Said substantially spherical end of inner rod  386  is configured with three flats that allow it to be insertable past the said three flared edges of central spherical socket in cradle  389 . Cradle  389  is subsequently rotated with respect to centerline of inner rod  386 , such that said flared edges on central spherical socket engage with a portion of the spherical end of rod  386  not interrupted by said flats. This results in cradle  389  and inner rod  386  being movably connected while being pivotingly engaged. This orientation of cradle  389  relative to inner rod  386  is maintained when the spherical ends of each of the three transmission cables  340  are engaged with the spherical sockets in lobes  388  while said cables are located in channel  384 .  
         [0117]    The center socket in cradle  389  is pierced by a threaded hole (not shown), at its topmost point, to cooperate with securing bolt  385 . Applying a torque on said bolt results in a force being exerted on the spherical end of rod  386 , thereby securing said spherical end against the three flared edges of cradle  389 . This results in a locked assembly. Loosening bolt  385  permits sliding at the spherical interface between spherical end of rod  386  and central socket of cradle  389 .  
         [0118]    Transmission cables  340  extend from a control section  380  to a heart-contacting section  300  through a connector section  390 . Said transmission cables slide in a substantially closed passage formed by longitudinal channel  384  and the inner diameter of hollow proximal shaft  360 . Said transmission cables  340  slide in a similar substantially closed passage formed by a longitudinal channel (not shown) in distal inner rod  352  and inner diameter of hollow distal shaft  350 . By pivoting the cradle  389  relative to spherical end of rod  386 , each of the articulation transmission cables  340  will slide within its respective closed passage, a variable and different amount based on the relative orientation of cradle  389  relative to inner rod  386 . By virtue of its connection with each of the transmission cables  340 , this variable and different amount of sliding experienced by each of the three cables will allow plate member  320  to assume a multitude of different spatial orientations. An annular brace  387  is inserted over inner rod  386  serving to retain cables  340  within their longitudinal channel  384  at the proximal control section  380 . A similar brace may also be installed at the distal heart-contacting section  300 .  
         [0119]    Each of the transmission cables  340  is configured with a distal spherical end  341 . Each of said spherical end  341  is engaged to a quick assembly/disassembly interface socket  321  on plate member  320 , thereby serving to connect heart-contacting section  300  with connector section  390 .  
         [0120]    Heart-contacting section  300  is comprised of at least one contact member  301 , a shaft member  323 , a plate member  320 , and a bushing  322 . Contact member  301  is configured by two elongated contact arms  302  defining therebetween an arterial window  304 . Two arms  302  are preferably substantially parallel and configure a substantially planar contact surface. Two contact arms  302  may be provided with a textured underside surface  305  to improve adherence with the surface of a beating heart when placed in contact with said heart.  
         [0121]    Contact member  301  serves to immobilize a portion of the surface of the beating heart proximate to a target coronary artery that will require a surgical intervention, such as an anastomosis. Contact arms  302  are shaped to be capable to press against the surface of a beating heart. Said arms are positioned on the said surface of a beating heart in such a manner as to straddle the target coronary artery proximate to the arteriotomy site within the arterial window  304 . Contact member  301  is rigidly connected to shaft member  323 . Bushing member  322  is rigidly connected to plate member  320  on opposite side of sockets  321 . Shaft member  323  is rotatingly engaged with bushing member  322 .  
         [0122]    Axis B is the longitudinal axis of rotation of shaft member  323 . Axis E is parallel to the plane containing plate member  320  and is normal to Axis B. Axis D is the longitudinal axis of distal shaft  350 . Axis D substantially intersects Axes B and E.  
         [0123]    The substantially planar contact surface of contact member  301  may be positioned and oriented with respect to distal shaft  350  through plate member  320  which is in turn positioned and oriented through its connection with transmission cables  340  which respond to a surgeon input applied at cradle  389 . This results in two motion degrees of freedom. The first motion degree of freedom is a rotation about Axis E which causes contact member  301  to tilt relative to distal shaft member  350 . The second motion degree of freedom is a rotation about Axis B which causes contact member  301  to yaw relative to distal shaft member  350 .  
         [0124]    The coronary stabilizer  30  may also be provided with an additional adjustment that allows distal shaft member  350  to pivot relative to proximal shaft member  360  about Axis A. Axis A is the centerline through hinge  361 . This additional adjustment allows the heart contacting member  301  to be set in a position and orientation substantially offset from the longitudinal axis of access cannula  10 , when said contact member  301  extends distally beyond the distal open end  115  of said access cannula. This additional adjustment is especially useful in adjusting the orientation and position of the contact member  301  relative to access cannula  10 , in a manner that tends to improve the presentation of said contact member on the target arteries located on the wider portions of a beating heart. This improved presentation of contact member  301  on the surface of the beating heart proximate to the target coronary artery also tends to improve the efficacy of the subsequent imposed immobilization by said contact member. The rotation of dial  371  entrains through its engagement with a sliding member (not shown) within the proximal shaft  360  the translation of elbow  370  within slot  362 . As a result, shaft  350  pivots about hinge  361  to a desired angle. The eccentricity of distal hinge  351  with respect to proximal hinge  361  results in a bias direction of pivot when a torque is applied to adjustment dial  371 . This results in a fourth motion degree of freedom namely pivoting about Axis A which is coincident with centerline of hinge  361 .  
         [0125]    Inner rod  386  is rotatingly engaged with proximal shaft  360  along its longitudinal Axis C. Inner rod  352  is rotatingly engaged with distal shaft  350 . Rotating cradle  389  relative to proximal shaft  360  about axis C entrains a rotation of plate member  320  by virtue of the simultaneous engagement of cables  340  with the sockets in lobes  388  of cradle  389 , the longitudinal channels  384  in inner rod  386 , and the interface sockets  321  in plate member  321 . This results in a fourth motion degree of freedom namely, rotation about axis D which allows contact member  301  to revolve about said axis relative to distal shaft member  350 .  
         [0126]    Coronary stabilizer  30  may also be provided with an additional adjustment enabling the rotation of contact member  301  about Axis B. This allows the angular orientation of the arterial window  304  with respect to shaft  350 , in order to more adequately access target arteries that are disposed in a diagonal orientation with respect to the long axis of the heart. Rotation of dial  331  acts on a fourth return transmission cable  330 , which in turn applies a torque on shaft  323  attached to contacting member  301 . Shaft  323  rotates within bushing  322 . This results in an increased range for the second motion degree of freedom, that is, rotation about axis B.  
         [0127]    Coronary stabilizer  30  tends to react mostly the local forces exerted by the underlying pulsating myocardium that it immobilizes. The loads associated with positioning and orienting the entire beating heart within the thoracic cavity are reacted mostly by the heart manipulator  20 .  
         [0128]    To achieve a substantially bloodless surgical field during beating a heart bypass surgery, heart contacting member  301  is configured with at least one wire attachment pedestal  310 . As illustrated in FIG. 10, four such pedestals  310  are provided, two pedestal  310  on each of contact arms  302  disposed on opposite sides of arterial window  304 . Said pedestals  310  serve to engage a vessel occluding wire  303 , preferably a silicone elastomer vascular loop. One said wire circumvents the target artery upstream of the grafting site while the other circumvents the target artery downstream of the grafting site. The two loose ends of each said wire  303  are subsequently engaged in opposing pedestals  310  located on opposite contact arms  302 . As such, the target artery is substantially snared by the deployment of said wire  303  tending to occlude said artery and create a substantially bloodless surgical field. The said pedestals  310  are each provided with at least one slit which tends to achieve a light-tight anchoring of vessel occluding wire  303 . Light-tight anchoring will retain said wire  303  engaged with said slit in pedestal  310  up until a threshold tension is applied to the occluding wire  303 . At this point, said wire will begin to slip through said slit. This tends to favor non-traumatic disengagement of said wire from said slit in the eventuality of an unwanted slippage of the coronary stabilizer  30  or an undesirable movement of the beating heart. Said slits in pedestals  310  allow a surgical wire  303  in the nature of a silicone elastomer vascular loop engaged therein to be pulled through said slit from a first engaged position to a second engaged position without having to disengage said wire from said slit.  
         [0129]    When proximal shaft member  360  of coronary stabilizer  30  is engaged in internal joint  190  (or like joint  180 ), said internal joint in its free state will provide four motion degrees of freedom. That is: translation of proximal shaft member  360  along centerline of bore  195 , rotation of proximal shaft member  360  about centerline of bore  195 , pivoting of proximal shaft member  360  about centerline through bore  192 , pivoting of proximal shaft member  360  about an axis perpendicular to centerline through bore  192  and simultaneously perpendicular to centerline of bore  195 . In addition, when internal joint  190  (or  180 ) is in its free state, four additional motion degrees of freedom about axes A, B, D and E are provided by virtue of the design of coronary stabilizer  30 . When internal joint  190  (or  180 ) is in its locked state the motion degrees of freedom offered by internal joint  190  (or  180 ) become locked. However, the four additional degrees of motion offered by the design of the coronary stabilizer  30  may still be exploited through a surgeon input applied at either cradle  389 , dial  331 , dial  371  or any combination thereof. A surgeon input applied at proximal control section  380  results in a linked corresponding movement of heart contact section  300  within the internal body cavity and downstream of anatomic barrier. As such, this provides an additional level of adjustment which may be exploited to tend to optimize the presentation of coronary stabilizer  30  upon the beating heart in addition to the “fine adjustment” and “coarse adjustment”. This additional level of adjustment also provides a means for readjusting the contact pressures exerted by the coronary stabilizer during a surgical procedure, without having to disrupt the “fine” and “coarse adjustments”.  
         [0130]    The design concepts described in reference to coronary stabilizer  30  may also be applied to a heart manipulator  20 , especially if heart contacting member  200  is a non-flowing static suction cup. As such, the heart contacting member  200  may be further deployed in space relative to the distal end  226  of shaft member  220 .  
         [0131]    Referring to FIGS. 7, 11A and  11 B, heart manipulator  20  and coronary stabilizer  30  are illustrated engaged with access cannula  10  and with a beating heart. Handle  240  and control section  380  extend beyond proximal opening  116  into the extracorporeal space ECS. Heart contacting member  200  and heart-contacting section  300  extend into the pleural space PLS beyond the diaphragm DG and downstream of open end  115 . Heart contacting member  200  and heart-contacting section  300  are engaged with target internal cardiac tissue, more specifically a portion of a beating heart surface. FIG. 11A illustrates a beating heart oriented and positioned relative to access cannula  10  by heart manipulator  20  so that coronary stabilizer  30  may access the posterior surface of the heart. FIG. 11B illustrates a beating heart oriented and positioned relative to access cannula  10  by heart manipulator  20  so that coronary stabilizer  30  may access the anterior surface of the heart.  
         [0132]    FIGS.  17 A- 17 D illustrate a variant to the first embodiment according to the present invention. Coronary stabilizer  31  and heart manipulator  21  are substantially fully enclosed within the at least one hollow passageway  213  of access cannula  10 , in an initial retracted state (FIGS. 17A, 17B). Hollow shaft  363  of coronary stabilizer  31  is engaged with an internal joint (not shown) within hollow passageway  213 , located upstream of seal member  211 . Coronary stabilizer  31  is comprised of a substantially fixed joint  364  between hollow shafts  363  and  366 , and a pivoting joint  365  between hollow shafts  366  and  367 . Longitudinal axes of shafts  363  is substantially parallel to longitudinal axis of access cannula  10 . Shaft  366  is substantially perpendicular to shafts  363 .  
         [0133]    Contact member  310  is engaged with distal end of hollow shaft  367 . At least three articulation cables (not shown) extend through each of hollow shafts  367 ,  366 ,  363  and serve to position and orient contact member  310  relative to shaft  367  in a similar manner to the first embodiment. In addition, contact member  310  may also revolve around the longitudinal axis of shaft  367  by virtue of a torsional cable also disposed along hollow shafts  367 ,  366 ,  363 . A proximal control section similar to  380  of the first embodiment is also provided (not shown) to tranfer the surgeon input to the heart contacting member  310 .  
         [0134]    Hollow shaft  209  of heart manipulator  21  is engaged with an internal joint (not shown) within hollow passageway  213 , located upstream of seal member  211 . Heart manipulator  21  is comprised of two hollow shafts  209 ,  208  connected through a substantially rigid joint  210  in a substantially perpendicular orientation. The centerline of shaft  209  is substantially parallel with the longitudinal axis of access cannula  10 . Heart contact member  250  is comprised of an elastic conical sheath  206  which is rotatingly engaged with shaft  208  through rotatable pneumatic joint  207 . Tissue-engaging perimeter  212  engages with the surface of the beating heart in a similar fashion to the first embodiment. Said joint  207  is rotatable in order to provide torsion free displacements to a beating heart which is engaged through sheath  206 .  
         [0135]    In the retracted state, hollow shaft  208  of heart manipulator  21  rests between the contact arms of contact member  310 . Access cannula  10  is preferably cylindrical and shafts  363 ,  209  are preferably diametrically opposed relative to the centerline of access cannula  10 . This tends to minimize the overall dimensions of access cannula  10  needed to fully enclose coronary stabilizer  31  and heart manipulator  21  in the retracted state within hollow passageway  213 .  
         [0136]    Heart manipulator  21  is deployed before coronary stabilizer  31 . Heart manipulator  21  is extended into the thoracic cavity sufficiently to be able to rotate freely about the centerline of shaft  209  without interfering with contact arms of retracted coronary stabilizer  31 . Heart manipulator  21  may extend further into thoracic cavity until it is capable of coming into contact with the target internal cardiac tissue, preferably the apex of the beating heart. The rotation of heart contact member  250  about the centerline of shaft  209  is a “fine adjustment” motion degree of freedom enabled by the internal joint. Said internal joint secures the position and orientation of heart manipulator  21  relative to access cannula  10 .  
         [0137]    When access cannula  10  is secured in a desired position and orientation relative to surgical arm  50  (coarse adjustment), and when the internal joint engaged with shaft  209  of heart manipulator  21  is in its free state, center CX of heart contact member  250  is free to assume any position along circumference CHC, for a given distance between point CX and center of said internal joint. As such, heart contact member  250  orbits around the centerline of shaft  209 . If sheath  206  is engaged with the surface of a beating heart, then said sheath  206  also rotates about point CX as it orbits, by virtue of rotatable joint  207 .  
         [0138]    When access cannula  10  is re-oriented within channel clamp  510 , thereby rotating about its centerline axis, circumference CHC orbits about the centerline of access cannula  10  along a trajectory ORB. If the apex of a beating heart is engaged with sheath  206  during this re-orientation of access cannula  10 , then the apex will also orbit about the centerline of access cannula  10  but will not rotate. By rotating access cannula  10  in the manner just described, all surfaces of the heart are generally accessible by coronary stabilizer  31  which is independently deployed relative to heart manipulator  21 .  
         [0139]    Referring to FIG. 17C, almost any point within the area ACHC may be engaged by sheath  206  through the combination of a rotation of heart contact member  250  about the centerline of shaft  209  (fine adjustment) and a rotation of access cannula  10  about its centerline (coarse adjustment). Once engaged, this point may be subsequently positioned and oriented relative to access cannula  10  by a combination of coarse and fine adjustments  
         [0140]    [0140]FIGS. 18A and 18B illustrate variants in heart contacting member  250 . FIG. 18A illustrates a heart contacting member comprising a plurality of substantially rigid finger-like protrusions  291 . FIG. 18B illustrates a heart contacting member comprising a substantially hemi-cylindrical cradle  292  with perforations  294  to allow anchoring preferably to the apex tissue of a beating heart with an associated suture  293 .  
         [0141]    By way of a general overview, FIG. 20 illustrates a surgical apparatus  2  according to a second embodiment of the present invention. The surgical apparatus  2  is comprised of a surgical arm  50 , an access cannula  10 , a heart manipulator  20 , a coronary stabilizer  30 , and a variety of endoscopic instruments  90 . Endoscopic instruments  90  represent a variety of surgical instruments well-suited to perform a surgical intervention on a beating heart while deployed through access cannula  10 . At least a portion of each of the surgical instruments comprising endoscopic instruments  90  is able to engage access cannula  10  through an internal joint such as internal joint  180 . Some of the surgical instruments comprising endoscopic instruments  90  may also be deployed through access cannula  10  during a part of a surgical procedure without being engaged in said internal joint  180 . Endoscopic instruments  90  are generally deployed while heart manipulator  20  is engaged with a beating heart and while heart manipulator  20  is securing a desired position and orientation of said beating heart with the aim of facilitating the surgical procedure performed by endoscopic instruments  90 . In other instances, endoscopic instruments  90  may be deployed while both heart manipulator  20  and coronary stabilizer  30  are engaged with a beating heart. Endoscopic instruments  90  may be comprised of some conventional endoscopic instruments capable of being engaged within said internal joint  180 .  
         [0142]    [0142]FIG. 22A illustrates a surgical method of harvesting an internal mammary artery IMA by using endoscopic instruments which are engaged with access cannula  10 . Endoscopic scissors  92  are used to section internal mammary artery IMA from the internal wall of the thoracic cavity, while endoscopic forceps  91  hold and suitably position the internal mammary artery. Alternatively, endoscopic scissors  92  may be replaced by a scalpel, a cauterizing scalpel, an ultrasonic scalpel, or other like means.  
         [0143]    [0143]FIG. 22B illustrates a surgical method for deploying a pericardial traction suture  94  through the use of endoscopic instruments  90 . Endoscopic forceps  91  pinch pericardium tissue PCT while endoscopic needle holder  93  simultaneously pierces the pericardial tissue with needle  941 .  
         [0144]    [0144]FIG. 22C illustrates a surgical method of securing a pericardial traction load by engaging traction suture  942 . A pericardial traction suture  942  is first engaged through an aperture  952  disposed on a member  951 , which extends distally away from the distal end of access cannula  10  into the pleural space. Subsequently, said suture  942  is anchored into an anchoring port  955 . Suture  942  is anchored by virtue of a wedging action produced when plug  953  is inserted into aperture  954  thereby trapping said suture  942 .  
         [0145]    [0145]FIG. 22D illustrates a surgical method of performing a proximal anastomosis of bypass graft BPG onto descending aorta DA. The method illustrated comprises the use of a shape memory alloy stent to anchor bypass graft BPG to descending aorta DA. Bypass graft BPG may be engaged with said stent extracorporeally prior to introducing said bypass graft into the thoracic cavity. Alternatively, a side biting clamp can engage a portion of descending aorta DA thus isolating a part thereof and the bypass graft can be sutured onto the aorta after opening a suitably sized hole in the isolated portion of the aorta.  
         [0146]    [0146]FIG. 22E illustrates a surgical method of performing an arteriotomy incision in a target artery. The target artery is occluded by engaging occluding wires  303  in pedestals  310 , and applying sufficient tension to occluding wire such that snaring occurs. Endoscopic scissors  92  engage the target artery to excise a portion thereof while beating heart BH is locally immobilized by engaging contact member  301  of coronary stabilizer  30  with the heart surface proximate to the target artery. Bulldog clamp  96  engages bypass graft BPG to occlude blood flow from the descending aorta. Occluding wires  303  are engaged with the target artery by using forceps  91 . Forceps  91  and scissors  92  are deployed through access cannula  10 .  
         [0147]    [0147]FIG. 22F illustrates a surgical method for performing of a distal anastomosis to a target coronary artery. Two forceps  91  engage and immobilize bypass graft BPG while endoscopic needle holder  93  engages suture  97  with bypass graft BPG. The proximal forceps  91  also function to occlude the bypass graft and thus prevent bleeding through the patent graft during surgery.  
         [0148]    [0148]FIG. 22G illustrates a surgical method of performing doppler ultrasonography with an endoscopic ultrasonic doppler probe  971  engaged with bypass graft BPG.  
         [0149]    Referring to FIGS.  21 A- 21 C, a hollow passageway  995  of an access cannula  10  may be reserved for engagement with a cartridge  99 . Cartridge  99  is configured with at least one hollow passageway  996  which extends from a proximal open end to a distal open end. At least one surgical instrument, such as a forcep  91 , is preferably permanently engaged within an internal joint disposed within said hollow passageway  996 . An internal joint such as  180  or  150  is preferable, although other internal joints with fewer motion degrees of freedom may also be used. Hollow passageway  996  may be provided with a seal member  70  (not shown) in order to preserve the ambient conditions present within the internal body cavity. A seal member  993  may also be provided within hollow passageway  995  of access cannula  10  in order to preserve the ambient conditions present within the internal body cavity during changeover of cartridges or when no cartridge is engaged with said hollow passageway  995 . Seal member  993  is displaced by cartridge  99  during installation of said cartridge into passageway  995  as illustrated in FIG. 21C. As such, during the installation and removal of cartridge  99  there is always at least one seal member,  993  or  70 , acting to seal hollow passageway  995 . When cartridge  99  is fully assembled into access cannula  10 , distal end  998  of representative surgical instrument  91  extends distally beyond distal open end  115  of said access cannula  10 , and proximal end  997  extends proximally beyond proximal open end  116  of said access cannula  10 . A handle member in the nature of a flange  991  is also provided serving to limit the amount of insertion of said cartridge  99  into said passageway  995 , and also serving to extract said cartridge  99  from access cannula  10 . Feature  992  on cartridge  99  and feature  997  on access cannula  10  cooperate to provide a locking means between said cartridge and said access cannula. For instance, a quarter turn fastener, a detented pin, a screw, a wire, or other like means may be used. Alternatively, locking may be provided by virtue of a snug fit between cartridge  99  and access cannula  10 .  
         [0150]    A variety of cartridges may be assembled, wherein each cartridge is comprised of a different surgical instrument. Each different cartridge is intended for a different surgical procedure. Used in this manner, cartridges may facilitate or accelerate the substitution of a surgical instrument engaged in a hollow passageway of access cannula  10  by a different surgical instrument to be used in a subsequent surgical intervention. A cartridge may also serve to bundle two or more different surgical instruments (or two or more similar surgical instruments), which are used in conjunction to perform a particular surgical intervention. This allows a rapid changeover in surgical set-up from a first surgical intervention to a subsequent different surgical intervention. For instance, a cartridge bundling surgical instruments for performing harvesting of an internal mammary artery may be rapidly disengaged from access cannula  10  and replaced with a cartridge bundling surgical instruments for performing a distal anastomosis.  
         [0151]    [0151]FIG. 12 illustrates a pericardium retraction device  69  may be engaged in a hollow passageway  120  of access cannula  10  through an internal joint  180 . In order to assist in the positioning and orienting of a beating heart generally during posterior artery revascularization, a suture  67  may be placed through the incised pericardium tissue  68 . A pericardium traction force may be applied to said suture through said device  69 . This helps to lift and orient the heart within the thoracic cavity. The amount of protrusion of device  69  from the distal open end  115 , along with the fine adjustment position and orientation of said device  69  within internal joint  180  will determine a vector direction in which the pericardium retraction load is applied to pericardium tissue by virtue of engaged suture  67 . Said pericardium retraction device may be used singly or may assist the heart manipulator  20  in setting the desired position and orientation of a beating heart.  
         [0152]    In broad terms, the surgical procedure for the set-up and deployment of the surgical apparatus during a beating heart CABG surgery, and relating to the present invention consists of:  
         [0153]    1. Performing a single lung deflation, preferably on the left lung, in order to augment the pleural space PLS available for subsequent deployment of surgical apparatus within a closed chest;  
         [0154]    2. Inserting one or more visioning ports into the thoracic cavity through intercostal port incisions (this step may be optional if such ports will only be deployed through an access lumen in access cannula  10 );  
         [0155]    3. Performing an abdominal incision (Al) preferably in the upper left quadrant of the patient;  
         [0156]    4. Inserting a laparoscopic cannula  499  into the abdominal incision AI and directing it into the underlying extra-peritoneal space EPS, generally in a direction towards the patient&#39;s head;  
         [0157]    5. Introducing CO2 gas through a hollow laparoscopic cannula  499  to assist in the dissection of the extra-peritoneal space EPS and the lateral displacement of viceral organs (VO) contained within the peritoneum (PER);  
         [0158]    6. Creating a sagittal tunnel spanning from the site of the abdominal incision AI to the patient&#39;s diaphragm DG, preferably in the vicinity of the left leaflet of the diaphragm;  
         [0159]    7. Inserting a guide wire  400  through the center of laparoscopic cannula  499  in order to pierce diaphragm and obtain access into the thoracic cavity and more specifically the pleural space PLS;  
         [0160]    8. Retrieving from the patient&#39;s body laparoscopic cannula  499 , leaving behind guide wire  400  extending from the extracorporeal space, through the abdominal incision, along the sagittal tunnel, through the diaphragm, and into the pleural space;  
         [0161]    9. Channeling a hollow enlarging cannula  402  (with conical tip) over guide wire  400  in order to reach the diaphragm and subsequently pierce through said diaphragm, preferably with a Seldinger technique, in order to obtain access into the pleural space;  
         [0162]    10. Inserting diaphragm tissue retractor  40  over enlarging cannula  402  in order to further pierce diaphragm;  
         [0163]    11. Retracting diaphragm tissue to obtain access into the thoracic cavity and more specifically into the pleural space;  
         [0164]    12. Once the desired retracted opening in the diaphragm is obtained, inserting access cannula  10  through the center of diaphragm retractor  40  in a manner that the distal open end  115  of said cannula extends at least partially within and communicates with the pleural space;  
         [0165]    13. Retrieving the diaphragm retractor  40  from the patient&#39;s body leaving in place access cannula  10  engaged with the retracted diaphragm at location of weir  130 ;  
         [0166]    14. Deploying a visioning port into pleural space through an access lumen in access cannula  10  (optional if only intercostal port access will be used for vision system);  
         [0167]    15. Introducing CO2 gas into the closed chest thoracic cavity of the patient either through an access lumen  125  in access cannula  10  or through an intercostal port incision, thereby augmenting the available pleural space through a displacement of the diaphragm caused by a pressure load acting on the dome of the diaphragm;  
         [0168]    16. Alternatively, if CO2 is not introduced, applying a pulling load to access cannula  10  which will also displace diaphragm by virtue of its engagement with weir  130  thereby augmenting pleural space;  
         [0169]    17. Positioning and orienting access cannula  10  relative to the patient&#39;s pleural space and target internal cardiac tissue contained therein;  
         [0170]    18. Securing access cannula  10  in the desired position and orientation through its engagement with surgical arm  50 ;  
         [0171]    19. Surgical harvesting of the internal mammary artery (IMA) if so required for a bypass graft. Deploying a forcep and cauterizing scalpel or a forcep and surgical scissor through the at least one hollow passageway  120  of access cannula  10  (FIG. 22A);  
         [0172]    20. Incising the pericardium tissue of the beating heart, at least in the vicinity of the target coronary artery, to expose the myocardium prior to a distal anastomosis (for multi-vessel CABG cases incising the pericadium along the long axis of the heart preferably with an inverted T incision) (FIG. 22E);  
         [0173]    21. Engaging a portion of the surface of the beating heart, preferably the apex, with a heart manipulator  20 . (In single vessel CABG cases the heart manipulator  20  may be engaged with the pericardium tissue if the pericardiotomy incision was substantially small);  
         [0174]    22. Deploying heart manipulator  20  in order to position and orient the beating heart within the thoracic cavity in a desired position and orientation for a surgical procedure;  
         [0175]    23. Rotating access cannula  10  with respect to its centerline in order to select the optimum path for the deployment of coronary stabilizer  30  through access cannula  10 , given the specific patient anatomy;  
         [0176]    24. If desired, engaging the pericardium tissue, preferably the incised pericardium tissue, with a suture and applying a retraction load through pericardium retraction device  69  to assist in the positioning and orientation of the beating heart;  
         [0177]    25. Deploying coronary stabilizer  30  through access cannula  10  while engaged in internal joint  180 . Position and orient the heart contact member  301  through the numerous motion degrees of freedom offered in such a manner as to align the arterial window with the target coronary artery and the heart contact plane substantially tangent to the surface of the heart proximate to the target artery.  
         [0178]    26. Compressing the heart surface gradually until pulsating effect of beating heart is substantially suppressed by virtue of the imposed immobilization load.  
         [0179]    27. Securing the position and orientation of the coronary stabilizer through internal clamp  180 , securing bolt  385 , dial  371 , and dial  331 ;  
         [0180]    28. Entering a bypass vascular conduit into the pleural space either through a hollow passageway  120  or a designated access lumen  125  of access cannula  10 . The vascular conduit may be kept engaged with a forceps  91  that is secured in a desired position and orientation relative the beating heart thereby facilitating the distal anastomosis.  
         [0181]    29. Occluding the target coronary artery, at a location upstream and downstream of the grafting site, with two occluding wires  303  that are manipulated and placed into engagement with both the beating heart and pedestals  310  of the coronary stabilizer  30 , by two forceps  91  deployed through access cannula  10 ;  
         [0182]    30. Performing an arteriotomy incision through the arterial window  304  of the coronary stabilizer  30  with a surgical scissors  92  deployed through access cannula  10 ;  
         [0183]    31. Performing a distal anastomosis through the arterial window  304  of coronary stabilizer  30  with two forceps  91  and one needle holder  93  deployed through access cannula  10 ;  
         [0184]    32. Verifying graft patency of newly grafted conduit with an endoscopic ultrasonic Doppler  97  deployed through access cannula  10 ;  
         [0185]    33. Performing a proximal anastomosis on the aorta, preferably the descending aorta, with an endoscopic surgical instrument capable of rapidly connecting a shape memory alloy stent to which a vascular conduit is affixed to said descending aorta;  
         [0186]    34. Alternatively, performing a proximal anastomosis on the aorta by deploying an endoscopic side biting clamp, an endoscopic hole punch, an endoscopic forceps  91 , and one endoscopic needle holder  93  through access cannula  10 ;  
         [0187]    35. Verifying graft patency of newly grafted conduit with an endoscopic ultrasonic Doppler  97  deployed through access cannula  10 ;  
         [0188]    36. Once the distal and proximal anastomosis is completed, disengaging coronary stabilizer  30  from the beating heart surface and retract from said surface;  
         [0189]    37. In multi-vessel CABG surgeries, repeating procedure (steps 22-36) for other target coronary arteries arteries;  
         [0190]    38. Once all diseased arteries have been revascularized, retrieving access cannula  10  from the patient&#39;s body;  
         [0191]    39. Re-inflating deflated lung, and proceed to closing all surgical incisions through standard medical practice.  
         [0192]    A variety of different coronary artery grafts may be performed with the surgical apparatus according to the present invention. These include: a venous conduit grafted proximally to the descending aorta and distally to a target coronary artery, a harvested internal mammary artery grafted distally to a target coronary artery, a venous conduit grafted proximally to the substantially non-harvested internal mammary artery and distally to a target coronary artery; a radial artery conduit grafted proximally to the descending aorta and distally to a target coronary artery;  
         [0193]    In the preferred embodiments according to the present invention, access to the thoracic cavity was achieved by piercing at least a portion of the diaphragm. Alternatively, the concepts and principles of the present invention may also be applied to a thoraco-phrenic dissociation surgical approach, whereby access to the thoracic cavity is achieved through a tunnel or passage created between the diaphragm and the patient&#39;s ribcage without piercing or penetrating the diaphragm.  
         [0194]    In the preferred embodiments according to the present invention, access to the diaphragm and subsequently the thoracic cavity was achieved via the extraperitoneal space. Alternatively, the concepts and principles of the present invention may also be applied to an intraperitoneal surgical approach, in which at least a portion of the patient&#39;s peritoneal membrane is pierced or penetrated prior to attaining the thoracic cavity beyond the diaphragm.  
         [0195]    Those skilled in the art will appreciate that the anatomic routing selected to attain the thoracic cavity according to the present invention may vary without departing from the spirit of the invention. Also, the thoracic cavity may be attained simultaneously though the deployment of one or more access cannulae  10  according to the present invention. For instance, one access cannula may be deployed to access the left pleural space, and one may be deployed to access the right pleural space.  
         [0196]    Some of the features and concepts of the surgical apparatus according to the present invention may also be used in cardiac surgery performed through an open chest approach, whereby the patient&#39;s thoracic structure is not left anatomically intact during the said cardiac procedure. For instance, open chest cardiac surgery performed through a sternotomy incision where the patient&#39;s sternum is incised the ribcage subsequently retracted, open chest cardiac surgery performed though an intercostal thoracotomy where two adjacent ribs are laterally spread apart, open chest cardiac surgery through an intercostal thoracotomy including a partial extraction of a portion of a rib, or other open chest cardiac surgeries performed through other like surgical incisions in order to access internal cardiac tissue. In these open chest cardiac surgeries, the patient&#39;s thoracic structure constitutes the anatomic barrier according to the present invention.  
         [0197]    In the same spirit, some of the features and concepts of the surgical apparatus according to the present invention may also be used in cardiac surgery performed through an intercostal access port whereby the patient&#39;s thoracic structure is left anatomically intact (closed chest) during the said cardiac procedure. Here again the patient&#39;s thoracic structure constitutes the anatomic barrier according to the present invention.  
         [0198]    A number of preferred embodiments have been described in detail and a number of alternatives have also been described. As changes in, or additions to, the above described embodiments may be made without departing from the nature, spirit or scope of the invention, the invention is not limited by or to those details, but only by the appended claims.