Abstract:
An adjustable multi-bladed tissue retractor capable of producing an incrementally variable or fine-tunable retracted opening in a surgical incision, or a body cavity. The adjustable tissue retractor comprises an actuator coupled to a retractor housing and a movable linkage arrangement capable of moving the plurality of tissue-engaging blades attached thereto, between a closed-blade configuration and an open-blade configuration. Through the application of a predetermined input to the actuator, a controlled, or selectable spaced apart spatial relationship of the plurality of tissue retracting blades results, and whereby, in use, the tissue retractor may be customized, or individually tailored to suit the specific anatomy of the patient.

Description:
[0001]    This application claims the benefits of U.S. Provisional Patent Application 61/213,075 filed May 5, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of surgical instruments to retract a body tissue and more specifically, to adaptable tissue retractors that may be adjusted in use to comply with a specific anatomy of a patient, or specific geometry of a surgical incision, body cavity or opening. 
       BACKGROUND OF THE INVENTION 
       [0003]    Current tissue retractors, especially in cardiac surgery, are typically of a fixed geometry. They are most commonly configured at the tissue-retracting end with either a “basket” type configuration made from spaced apart wire frame members, or with an uninterrupted and shaped tissue contacting surface or blade that engages the body tissue to be retracted. Consequently, the tissue-retracting end of these existing retractors is not adjustable or adaptable to suite the specific anatomy of the patient, but it is the patient&#39;s anatomy that is urged to adapt to the fixed geometry configuration of such existing tissue retractors. Tissue retractors with malleable tissue-retracting ends may be manually bent by the user, prior to engaging same with the body tissue to be retracted, but such manipulation is not selectively fine-tunable a predetermined amount while the tissue retractor is deployed in use, and the tissue-retracting end thereof is in contact with the body tissue being retracted. Usually, such malleable tissue retractors may only be grossly configured to approximate the most desirable configuration required. Increasing the malleability of the tissue-retracting end may result in insufficient retractor stiffness to be able to positively retract the body tissue under load. 
         [0004]    In cardiac surgery requiring the retraction of heart tissue, for instance in a mitral valve surgery practiced via a left atrial approach, commonly used retractor platforms include the “Cosgrove-type” and “Carpentier-type” retractor platforms. In using the “Cosgrove-type” retractor platform (see  FIG. 1 ), generally three fixed geometry basket-type tissue retractors are deployed to retract the incised cardiac tissue. Each of these tissue retractors is independently mounted or secured to a sternal retractor, or stable surgical platform, to achieve the desired retraction of the atrial incision and to obtain surgical access to the target mitral valve. In using the “Carpentier-type” retractor platform (see  FIG. 2 ), generally two tissue retractors with fixed shape tissue contacting surface are deployed and mounted to a sternal retractor. The lack of adaptability with these current tissue retractors, and their inability to spread or retract a body tissue in more than one traction direction, results in the need to deploy a plurality of tissue retractors each independently mounted to the surgical platform generally in a different traction direction. Consequently, the associated surgical set-up is time-consuming given the high part count, and the ergonomics of the surgical worksite is compromised given the plurality of individually-mounted tissue retractors to the sternal retractor. 
         [0005]    In-process re-adjustments of the plurality of tissue retractors with known valve surgery platforms may at times prove fastidious. For example, in a typical set-up with a Cosgrove-type retractor platform, two tissue retractors are generally mounted on a left sternal retractor spreader arm to retract cardiac tissue towards the patient&#39;s left side. A third tissue retractor is mounted on an extension rod or member to retract cardiac tissue towards the patient&#39;s feet. The extension rod is also mounted to the left sternal retractor spreader arm in a substantially perpendicular and generally horizontal orientation. If the surgeon wants to modify the orientation of the tissue-engaging or tissue-retracting end of the middle tissue retractor, for instance, the mounting clamp of the middle tissue retractor must be repositioned along the left sternal retractor spreader arm. Larger re-orientations generally require more translation of the mounting clamp along the left sternal retractor spreader arm. In certain cases, the re-orientation required is sufficiently great that the mounting clamp of the middle tissue retractor must be translated considerably along the left sternal retractor arm that it may interfere with the mounting clamp of an adjacent tissue retractor. This may lead to a major take town of the surgical set-up. 
         [0006]    Recently, with the advent of minimally invasive cardiac surgery gaining in popularity, the size of the surgical access incision and the size of the retracted surgical access thoracic opening are being progressively reduced. Vacuum-assisted venous drainage has been developed to reduce the size of venous cannulae used in cardiopulmonary bypass. The smaller sizes of these cannulae tend to prevent them from being obstructive to the surgical procedure. However, the number of traction sutures and number of tissue retractors, either hand held or chest-retractor-mounted, currently used in existing approaches tends to be obstructive in certain areas given the relatively smaller size of the surgical window. 
       SUMMARY OF THE INVENTION 
       [0007]    Thus, it is a first object of the present invention to provide a single, solitary tissue retractor configured with a plurality of tissue engaging blades (four or five blades), said tissue retractor being adaptable or adjustable in the relative positioning of the blades, and whereby, in use, the tissue retractor may be customized, or individually tailored to suit the specific anatomy of the patient or the specific geometry of a surgical incision with a desired spatial relationship of the plurality of blades. 
         [0008]    It is a further object of the present invention to be able to mount one such multi-bladed tissue retractor to a stable surgical platform and obtain the proper access to the target tissue to be operated, said target tissue being located within the perimeter of the retracted surgical incision or body cavity, without the need to deploy multiple individually bladed tissue retractors, each individually or each independently mounted to a stable surgical platform. 
         [0009]    It is a further object of the present invention to be able to retract tissue in a primary direction, and simultaneously by deploying blades from a blade closed to a blade open configuration, retract in a second retraction direction being substantially at (+90) degrees relative to this first primary direction, and also in a third retraction direction being substantially at (−90) degrees relative to this first primary direction and generally diametrically opposite to the second retraction direction. 
         [0010]    It is another object of the present invention to provide an adjustable multi-bladed tissue retractor capable of producing an incrementally variable or fine-tunable retracted opening or retraction perimeter through the application of a predetermined input to an actuator on the tissue retractor that results in a controlled, spaced apart spatial relationship of the plurality of tissue-retracting blades. 
         [0011]    It is another object of the present invention to provide an adjustable tissue retractor configurable or adaptable to achieve a desired tissue retraction with a plurality of blades that may be selectively interspaced between a closed blade configuration and an open blade configuration, said open blade configuration resulting in a substantially circular or arcuate retraction span of 200+/−20 degrees (with 4 blades) or 320+/−40 degrees (with 5 blades). 
         [0012]    These and other objects of the present invention will become apparent from the description of the present invention and its preferred embodiments which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    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 a tissue retractor apparatus according to preferred embodiments of the present invention, and in which: 
           [0014]      FIG. 1  is a perspective view of a prior art surgical platform commonly known as a “Cosgrove-type” retractor platform; 
           [0015]      FIG. 2  is a perspective view of a prior art surgical platform commonly known as a “Carpentier-type” retractor platform; 
           [0016]      FIG. 3  is a perspective view of a multi-bladed tissue retractor being configured with four tissue-retracting blades according to a preferred embodiment of the present invention; 
           [0017]      FIG. 4  is a top view of a multi-bladed tissue retractor illustrated in  FIG. 3 , with the tissue-retracting blades being in a closed-blade configuration; 
           [0018]      FIG. 5  is a top view of a multi-bladed tissue retractor illustrated in  FIG. 3 , with the tissue-retracting blades being deployed in an open-blade configuration; 
           [0019]      FIG. 6  is an enlarged bottom view of the tissue retractor in  FIG. 3  according to a preferred embodiment of the present invention; 
           [0020]      FIG. 7  is an exploded view of the tissue retractor illustrated in  FIG. 3  according to a preferred embodiment of the present invention; 
           [0021]      FIG. 8  is a cross-sectional view of a portion of the tissue retractor illustrated in  FIG. 3  according to a preferred embodiment of the present invention; 
           [0022]      FIG. 9  is a top view of a multi-bladed tissue retractor having five tissue-retracting blades according to a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    With reference to  FIGS. 3 and 7 , tissue retractor  1  is comprised of an actuator or actuating means  10 , a tubular housing  20 , a linkage mechanism, assembly or arrangement  30 , and a plurality of tissue-contacting, tissue-engaging or tissue-retracting blades, fingers or members  40 . Linkage arrangement  30  is mechanically coupled to tubular housing  20  at a first or distal end  21  thereof, through mechanical joint  22 . 
         [0024]    Linkage assembly  30 , as a whole, is pivotingly engaged and able to pivot relative to housing  20  about pivot axis  510 , regardless of the blade configuration assumed by tissue-engaging blades  40  and by virtue of flexible cable  11  as will be described in greater detail below. Linkage assembly  30  is able to articulate in a multitude of different linkage configurations, and consequently able to transmit a multitude of blade  40  spatial geometries, relative to said housing. As such, tissue retractor  1  is adaptable or adjustable to the desired retraction geometry or configuration. 
         [0025]    Actuator  10  is mechanically coupled to tubular housing  20 , at a second or proximal end  23  thereof. More specifically, and with reference to  FIG. 8 , actuator  10  is preferably rotatingly engaged to said housing proximal end  23  via a rolling element bearing, such as ball bearing  28 . End  23  of housing  20  is configured with an external circumferential groove  281  adequately sized to act as a bearing inner race for said bearing  28 . Actuator  10  consists of a first, knob part  19  configured with lobes  191  and assembled through a threaded interface  185  to a second, cooperating tubular part  18 . Knob part  19  is provided with a circumferential inner groove  192  and tubular part  18  with a second inner groove  182 . Grooves  192 ,  182  cooperate to form a circumferential outer race for bearing  28  when said parts  18 ,  19  are assembled together via threaded interface  185 , thereby axially retaining the rolling elements of bearing  28  within said grooves and also axially retaining said actuator  10  relative to said housing  20 . The trapped bearing now allows the free, low friction rotation of actuator  10  relative to housing  20 . 
         [0026]    Actuator tubular part or member  18  extends beyond terminal end of housing  20  to expose an internal thread  15 . Housing  20  is elongate and extends between first  21  and second  23  housing ends. Housing  20  is provided with an internal passageway or through bore  26  that extends between said first  21  and second  23  ends of tubular housing thus providing open communication therebetween. Said passageway is configured and sized to house or receive an actuating member therewithin, in the nature of a translating actuating cable  11 . Cable  11  is preferably flexible, and fabricated from surgical grade braided stainless steel wire. Cable first end  112  is provided with a spherical or ball end  12  configured to be insertable into a receiving socket or depression  301  disposed on linkage assembly  30  so as to allow for a demountable mechanical interface between actuator cable  11  and said linkage assembly, said mechanical interface secured in its mounted state through latch or clasp member  302 . Cable second proximal end  113  is provided with a threaded member or fitting  13  configured with an external thread portion  132  sized to engage internal thread  15  in actuator part  18  when said cable  11  is inserted in housing passageway  26 . Fitting  13  is also provided with an elongated tongue or key member  131  which is configured and sized to engage a longitudinal slot, groove or keyway  27  in terminal end of housing  20 . Keyway  27  communicates passageway  26  with the outer surface of tubular housing  20  and extends longitudinally along housing longitudinal axis at least as long as the length of tongue  131 . When cable  11  is inserted into passageway  26 , tongue  131  is first slidingly engaged with keyway  27 , and subsequently external thread  132  engages internal thread  15  in actuator  10 . 
         [0027]    During actuation of actuator  10 , applying an actuation input in the nature of a rotation to knob  19  results in a translation of cable  11  through housing  20  since tongue  131  and groove  27  cooperate to prevent said cable from rotating together with knob  19  as internal thread  15  urges or entrains cable external thread  132  to translate axially along with cable  11  relative to housing  20 . The resulting translation of actuation cable  11  relative to tubular housing  20  results in the extension (or retraction) of said cable beyond said housing distal end  21 , which in turn simultaneously entrains the articulation of linkage mechanism  30 , as will be described in greater detail below. 
         [0028]    As illustrated in  FIG. 6 , the center of socket  301 , that demountably engages terminal ball end  12  of actuator cable  11 , is generally aligned with pivot axis  520  of mechanical joint  52 . Joint  52  is configured to pivotingly engage linkage members  31  and  32  to each other, as well as blade  42  which is also pivotingly engaged thereto via its through-hole  421 . Linkage member  33  is pivotingly engaged, at a first end, to housing  20  through mechanical joint  51 , and it pivots about linkage pivot axis  510 . Blade  41  is pivotingly engaged to linkage member  33  at a blade mount location in the nature of mechanical joint  55 , and it pivots about blade pivot axis  550 . Approximately at the mid length location of linkage member  33 , linkage members  31  and  33  are pivotingly engaged through mechanical joint  53 . Linkage member  31  pivots relative to linkage member  33  about linkage pivot axis  530 . Linkage member  34  is pivotingly engaged, at a first end, to housing  20  through mechanical joint  51 , and it pivots about linkage pivot axis  510 . Approximately at the mid length location of linkage member  34 , linkage members  32  and  34  are pivotingly engaged through mechanical joint  54 . Linkage member  33  pivots relative to linkage member  34  about linkage pivot axis  540 . At a second end, linkage member  34  is pivotingly engaged to cross linkage member  36  at mechanical joint  58  located generally at the mid-span of member  36 . Cross linkage member  36  is pivotingly engaged to blade carrier linkage member  37  through mechanical joint  59 . Linkage member  37  is able to pivot relative to cross member  36  about pivot axis  590 , said pivot range being limited by mechanical stop feature or pin  71  extending proudly from surface of cross member  36  to limit the pivoting range of carrier member  37  relative to member  36 . Blades  43  and  44  are each pivotingly coupled to a respective free end of linkage member  37  via blade mounts or mechanical joints  62  and  61 , respectively. Said blades  43 ,  44  are able to pivot about blade pivot axes  620  and  610 , respectively. The pivoting range of cross member  36 , relative to linkage member  34 , is set by coupling linkage member  35  which is pivotingly engaged to a second terminal end of cross member  36  at mechanical joint  57 , and pivotingly engaged to linkage member  33  at mechanical joint  56 . Coupling linkage member  35  pivots relative to member  33 , about pivot axis  560 . Cross member  36  pivots relative to member  35  about pivot axis  570 . 
         [0029]    When actuator  10  is actuated by applying a rotational actuation input  100 , the extended portion of actuating cable  11  ( FIG. 6 ) is progressively retracted into passageway  26  of housing  10 . This moves blade  42  generally along a first movement direction “Y” towards tubular housing end  21 . Said translation of blade  42  entrains linkage members  31  and  32  to pivot in generally opposed directions relative to mechanical joint  52  where the latter are coupled, and simultaneously linkage members  33  and  34  to also pivot in generally opposed directions relative to housing  20  where the latter are coupled or connected at mechanical joint  51  on said housing. Consequently, blade  41  moves or swings in an arcuate trajectory about pivot axis  51 , said trajectory corresponding to movement or a change in position along both “X” and “Y” directions. Similarly, mechanical joint  58  moves in a generally opposed arcuate trajectory to blade  41 , also about pivot axis  51 . The resulting differential change in position along “X” and “Y” of mechanical joint end  57  relative to mechanical joint  58  for a given translation of cable  11  (and blade  42 ) along direction “Y”, establishes the amount that cross linkage member  36  pivots about axis  580 , and consequently also the position along “X” and “Y” of mechanical joint  59 . 
         [0030]    Pivot joint  59  acts as a fulcrum for carrier linkage member  37  which carries spaced apart blades  44 ,  43  from each other and from a fulcrum coincident with pivot axis  59 . This spacing between the fulcrum  59  and each of the respective blade pivot axes  610 ,  620  may be designed such that the orientation assumed by said carrier linkage  37  relative to the rest of linkage mechanism  30  will be determined by the relative force exerted on each of blades  43 ,  44  by the body tissue being retracted, said latter forces being magnified as a function of the moment arm (or spacing) between fulcrum  59  and respective blade pivot axes  610 ,  620  to reach equilibrium of the force couple exerted on blades  43 ,  44 . As such, the position of blades  43 ,  44  is set along direction “X” and “Y” as a function of the magnitude of translation of cable  11  along direction “Y”. The spacing between fulcrum  59  and each of respective blade pivot axes  610 ,  620  may be advantageously designed according to the type of incision or body cavity being retracted. 
         [0031]    Additionally, mechanical stops or restraints  71  may also be included between cross linkage  36  and carrier linkage  37  to intentionally limit the range of articulation of one linkage member relative to the other, and override the equilibrium orientation that would otherwise be achieved without the implementation of said mechanical stops  71 . Similar mechanical stops may also be incorporated between blades  41 ,  42 ,  43 , and  44  and the respective linkage member pivoting coupled to said blades to limit the pivoting range of said blades about their respective pivot axes  550 ,  520 ,  620  and  610 . 
         [0032]    Cable  11  is preferably flexible so as to allow flexing of the exposed cable portion extending beyond housing  20 . When blades  41 ,  42 ,  43 , and  44  are engaged with a body tissue to be retracted, this provides adaptability by allowing the entire linkage mechanism  30  to articulate and reorient itself as an entire assembly relative to tubular housing  20 , in any given linkage configuration (i.e blade closed, blade open, or intermediately therebetween). In addition, the adaptability of each of blades  41 ,  42 ,  43 , and  44  to pivot and orient themselves optimally relative to the body tissue being retracted results in a less traumatic tissue retraction. This adaptability tends to provide substantially equal or equilibrated reaction loads being applied by each blade to the contacted portion of body tissue being retracted. 
         [0033]    Blades  41 ,  42 ,  43 , and  44  are configured and sized for a particular tissue to be retracted. For instance, as illustrated in  FIG. 3 , blades  40  are intended to retract heart tissue such as tissue of the left atrium through a left atrial incision. Accordingly, terminal blade ends  412 ,  422 ,  432 , and  442  are bent to act as hook or retracting members during left atrial tissue retraction, but are also profiled to be blunt and atraumatic so as to not pierce body tissue. 
         [0034]    During deployment of tissue retractor  1 , said actuator  10  may rotate relative to said housing  20  in order to effect or apply an actuation input  100  to said tissue retractor which will deploy, adjust, or adapt the plurality of tissue-contacting blades  40  into a desired spatial arrangement suitable for a surgical procedure. Incremental variations in the actuation input  100  will result in a similar incremental variation in said spatial arrangement of tissue-engaging blades  40 . As such, a surgeon or user of said tissue retractor  1  may apply a predetermined actuation input to said actuator  10  to achieve a desired deployment or adjustment of said tissue-engaging blades  40 , said spatial relationship of blades  40  being well suited for the retraction of a particular surgical incision, or the opening of an anatomical body cavity. Tubular housing  20  is advantageously provided with a seat  24  for mounting or engaging said tissue retractor  1  to a substantially stable surgical platform such as, for instance, a sternal retractor for cardiac surgery as described in U.S. Pat. No. 6,837,851. Mounting tissue retractor  1  to a sternal retractor for cardiac surgery as the one recited in U.S. Pat. No. 6,837,851 will tend to avoid the hereinabove described drawbacks associated with individually mounting each of a plurality of known fixed geometry, basket-type tissue retractors to a “Cosgrove-type” retractor platform, as illustrated in  FIG. 1 . 
         [0035]    We will now describe in greater detail the deployment configurations of tissue retractor  1 . In a closed-blade configuration  400  as illustrated in  FIG. 4 , tissue-retracting blades  40  are in a substantially compact, closely-spaced blade arrangement and are disposed generally about a virtual blade geometric center “VBGC”. Said closed-blade configuration is advantageous to facilitate insertion of said tissue retractor  1 , and more specifically blades  40  thereof, in a non-retracted surgical incision or facilitate placement in a non-retracted body cavity. Then, as tissue retractor  1  is deployed by actuator  10 , said tissue retractor assumes a plurality of incrementally variable blade spatial positions whereby the relative spacing between blades is adjustable. The degree of blade opening is “fine-tunable” or selectable, and may be optimally set as a result of the actuation input  100  applied by the user to actuator  10 , so as to configure the adaptable tissue retractor to best adapt to the specific incision, or specific anatomy of the patient. 
         [0036]    With reference to  FIG. 5 , tissue retractor  1  is illustrated in an open-blade configuration  401 , said open-blade configuration being set to retract a surgical incision of body cavity schematically depicted as “RSI”. The span of tissue retraction established by four spaced apart blades  41 ,  42 ,  43 , and  44  in said open-blade configuration  401  forms an arc of retraction Θ 1  approximately 200+/−20 degrees, disposed generally around or about VBGC of blade  40  arrangement. As illustrated in  FIG. 5 , said open-blade arrangement (and more specifically blades  41 ,  42 , and  43 ) may provide retraction along a first retraction direction RD 1  when said tissue retractor  1  is manipulated or displaced to apply a retraction load to RSI along a direction generally aligned with longitudinal axis of housing  20 . As well, blade  44  may also provide a simultaneous retraction along a second direction RD 2  , said RD 2  direction being offset at 90 degrees relative to RD 1 . In the context of a cardiac surgery, and more specifically, valve surgery performed on a mitral valve via left atrial approach, tissue retractor  1  may be deployed so that blades  41 ,  42 ,  43  retract a first portion of a left atrial incision upwardly along RD 1  so as to rotate and lift heart within patients thorax, while blade  44  moves laterally to said blades  41 ,  42 ,  43  to retract a second portion of said left atrial incision along RD 2  generally towards patient&#39;s abdomen to improve surgical access to diseased mitral valve. In cases where a shorter left atrial incision is made, the pivoting range of blade  44  about pivot axis  610  allows said blade  44  to reorient itself through a clockwise rotation. As such, blade  44  will impart a retraction load having at least a force component that pulls or retracts tissue downwardly (i.e. in the negative RD 1  direction), or at a generally opposed incision side relative to blades  41 ,  42 ,  43  which cooperate to support the bulk of the weight of the patient&#39;s heart. 
         [0037]    Those skilled in the art of linkage mechanisms will appreciate that offset between pivot axes  560  and  510  as well as the offset between pivot axes  570  and  580  may be varied in the design of tissue retractor  1  in order to optimize a rate of displacement of blade  44  relative to other blades  41 ,  42  (or relative to the center of the retracted opening or VBGC). For instance, linkage mechanism  30  may be designed so that blade  44  moves laterally away from center of retracted opening or VBGC at a faster rate at the beginning of range of open-blade positions relative to the end of range of open-blade positions, for a given fixed rate of translation of action cable  11  relative to housing  20 . 
         [0038]    Alternatively, carrier linkage member  37  may be configured with an additional pivot joint (shown schematically as dashed line  630  in  FIG. 6 ) so as to allow blade  44  to pivot into or out of main retracting plane X-Y (plane of page of  FIGS. 5 and 6 ), for instance +/−20 degrees out of plane X-Y. This provides yet another additional degree of adaptability to tissue retractor  1  to allow said tissue retractor to more optimally adapt to certain surgical incision geometries or specific patient&#39;s anatomies with the aim of achieving less traumatic tissue retraction. 
         [0039]      FIG. 9  illustrates a second embodiment of a tissue retractor  2  according to the present invention. Tissue retractor  2  includes five tissue-retracting blades  41 ,  42 ,  43 ,  44 , and  45 . The span of tissue retraction established by said five spaced apart blades in an open-blade configuration  402  forms an arc of retraction Θ 2  approximately 320+/−40 degrees, disposed generally around or about VBGC of blade  41 ,  42 ,  43 ,  44 ,  45  arrangement. As illustrated, said open-blade arrangement may provide retraction along a first retraction direction RD 1  (blade  42 , component of blade  41 , component of blade  43 ) when said tissue retractor  1  is manipulated or displaced to apply a retraction load to RSI along a direction generally aligned with longitudinal axis of housing  20 . As well, blade  44  may also provide a simultaneous retraction along a second direction RD 2 , said RD 2  direction being offset at 90 degrees clockwise relative to RD 1 . As well, blade  45  may also provide a simultaneous retraction along a third direction RD 3 , said RD 3  direction being offset at 90 degrees counterclockwise relative to RD 1 , or being generally in opposed direction to RD 2 . In certain types of surgical incisions or body cavity retractions, typically those smaller in size, tissue retractor  2  may be deployed so that the arc of retraction Θ 2  substantially approximates a complete circumferential span, said span being retracted by five spaced apart tissue-retracting blades.