Abstract:
A surgical retractor includes a “swivel” having a string extending from one end and a string extending from the midpoint between the two ends. The swivel is delivered by pushing it out of a tube which is inserted through a small incision between the ribs of the patient. After the swivel is deployed, the tube is removed and the string which is attached to the center of the swivel is pulled to lift the pericardium. When the procedure is complete, the swivel is removed from the patient by pulling the string attached to the end of the swivel. According to one embodiment, the swivel is a cylinder with a blunt conical end. According to another embodiment, the swivel has a sharp end which is covered by a spring loaded collar.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 10/666,707, filed Sep. 19, 2003, to be issued as U.S. Pat. No. 7,341,558, on Mar. 11, 2008, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to minimally invasive surgery. More particularly, the invention relates to a pericardial retractor for use in endoscopic heart surgery. 
     2. State of the Art 
     When performing surgery it is sometimes necessary to open and retract soft tissues that envelop or block access to the organs or structures to be operated on. For example, in endoscopic heart surgery it is necessary to suspend the pericardium in order to access the heart. However, tissue retraction is difficult in minimally invasive or endoscopic surgery because of the limits of space and the small number of entry sites. 
     Several devices exist for the retraction of tissue during endoscopic and laparoscopic surgery. These devices are designed to be delivered into the body through a small incision or through an introduction tube which passes through a small incision. Typically, the retraction devices include a deployable member which is attached to a string or cable. After the device is deployed on the distal side of soft tissue, the string is pulled out of the body, thereby lifting the tissue. (As used herein, the term “distal” means farther from the practitioner and the term “proximal” means closer to the practitioner.) When the tissue is sufficiently retracted, the device is held in place by clamping the string with a hemostat or other type of clamp. 
     U.S. Pat. No. 5,613,939 to Failla discloses several complex deployable devices. Some of them are difficult to deploy and most of them are difficult to remove when surgery is complete. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a surgical retractor. 
     It is also an object of the invention to provide a surgical retractor which is suitable for use in endoscopic surgery. 
     It is another object of the invention to provide an endoscopic surgical retractor which is suitable for lifting the pericardium during endoscopic heart surgery. 
     It is still another object of the invention to provide an endoscopic surgical retractor which is simple in its construction and its use. 
     It is yet another object of the invention to provide an endoscopic surgical retractor which is easily deployed and equally easy to remove from the body when surgery is complete. 
     In accord with these objects which will be discussed in detail below, the surgical retractor of the present invention includes a “swivel” having a string extending from one end and a string extending from the midpoint between the two ends. As used herein, the term “string” is meant to include any suitable string-like member, e.g. a cable, filament, suture, etc. Moreover, the two strings may actually be a single length of string which is looped through the swivel or which has opposite ends attached to the swivel. The swivel is delivered by pushing it out of a tube which, when used in endoscopic heart surgery, is inserted through a small incision between the ribs of the patient. When the swivel member is deployed, the tube is removed and the string which is attached to the center of the swivel is pulled to lift the pericardium. When the procedure is complete, the swivel is removed from the patient by pulling the string attached to the end of the swivel. 
     According to one embodiment, the swivel is a cylinder with a blunt conical end and an opposite keyed end. The keyed second end is engaged by the distal end of a pushrod which is movable through a delivery tube. The tube and/or pushrod may be hereinafter referred to as a “deployment tool”. The proximal end of the delivery tube is coupled to a housing and the proximal end of the push rod is coupled to a push button in the housing. The push button has a locking ring which locks the pushrod in the deployed position when the push button is pushed. The strings attached to the swivel pass through the hollow pushrod and out of the housing. The strings are preferably different colors so that they can be distinguished one from the other. Alternatively, the strings may be labeled. 
     According to a second embodiment of the invention, the swivel has a sharp end which is covered by a spring loaded collar (safety shield). The swivel is coaxially mounted on the distal end of the delivery tube. The sharp end of the swivel is used to puncture the patient&#39;s chest and pericardium in order to introduce the device. Once introduced, the spring loaded collar slides over the sharp point so that it does not damage any tissues. A pushrod inside the delivery tube is used to deploy the swivel. 
     Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a first embodiment of a pericardial retractor according to the invention prior to insertion into the patient; 
         FIG. 2  is a broken perspective view of the retractor at initial insertion through the chest but prior to piercing the pericardium wall; 
         FIG. 3  is a perspective view of the retractor with the swivel partially deployed; 
         FIG. 4  is a broken perspective view of the retractor after piercing the pericardium with the swivel partially deployed; 
         FIG. 5  is a perspective view of the retractor with the swivel fully deployed; 
         FIG. 6  is a broken perspective view of the retractor after piercing the pericardium with the swivel fully deployed; 
         FIG. 7  is a perspective view of the retractor with the swivel fully deployed and released to perform retraction; 
         FIG. 8  is a broken perspective view of the retractor after piercing the pericardium with the swivel fully deployed and performing retraction; 
         FIG. 9  is a broken side elevation view illustrating removal of the swivel after surgery; 
         FIG. 10  is a broken longitudinal sectional view of the handle portion of the retractor; 
         FIG. 11  is a broken perspective view of the distal end of the retractor with the swivel detached from the pushrod; 
         FIG. 12  is an exploded perspective view of the proximal handle portion of the retractor; 
         FIG. 13  is a broken perspective view of the distal portion of a second embodiment of the invention; 
         FIG. 14  is a broken sectional view of the distal end of the retractor of the second embodiment; 
         FIG. 15  is a view similar to  FIG. 13  showing the swivel partially deployed; 
         FIG. 16  is a view similar to  FIG. 14  showing the swivel partially deployed; 
         FIG. 17  is a view similar to  FIG. 13  showing the swivel fully deployed; 
         FIG. 18  is a view similar to  FIG. 14  showing the swivel fully deployed; 
         FIG. 19  is a view similar to  FIG. 13  showing the swivel in position for removal from the surgical site; 
         FIG. 20  is a view similar to  FIG. 14  showing the swivel in position for removal from the surgical site; and 
         FIG. 21  is an exploded perspective view of the distal portion of the retractor. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIGS. 1-12 , a first embodiment of a surgical retractor  10  includes a hollow tube  12  having a proximal end  14  and a distal end  16 . A hollow pushrod  18  extends through the hollow tube  12 . The proximal end  14  of the tube  12  is coupled to a housing  20  which contains a push-button  22  which is coupled to the proximal end of the pushrod  18 . 
     A bullet shaped “swivel”  24  is removably mounted in the distal end  16  of the tube  12 . Two strings  26 ,  28  extend from the swivel  24  through the hollow tube  12  (preferably through the hollow pushrod  18 ) and exit through one or more holes  30  in the push-button  22 . As used herein, the term “string” can mean cable or suture or filament or wire or other similar structure. 
     As seen best in  FIGS. 9 and 11 , one of the strings  26  extends from substantially the midpoint along the length of the swivel  24  and the other string  28  extends from the proximal end of the swivel  24 . According to this embodiment, the swivel  24  has a blunt conical end  24   a , an axial bore  24   b , a radial bore  24   c , a shoulder  24   d , a T-shaped keyway  24   e , and a surface groove  24   f  which extends from the bore  24   c  to the proximal end of the swivel  24 . As seen best in  FIG. 11 , the strings  26 ,  28  are knotted together in the radial bore  24   c . If the strings  26 ,  28  are a single length of string, a knot or similar structure is provided at  24   c  to prevent the string from detaching from the swivel. 
     As seen best in  FIG. 11 , the distal end of the pushrod  18  is provided with a T-shaped key  18   a . This key is adapted to engage the keyway  24   e  in the proximal end of the swivel  24  prior to deployment of the swivel. This coupling is suggested in  FIGS. 4 and 6 . When the pushrod and swivel are coupled in this way, the proximal end of the swivel  24  up to the shoulder  24   d  is received by the distal end of the tube  12 . 
     Turning now to  FIGS. 10 and 12 , the housing  20  has two parts: a distal ferrule  20   a  and a proximal cover  20   b . The distal ferrule  20   a  is force fit onto annular ridges  14   a  at the proximal end  14  of the hollow tube  12  and the cover  20   b  is force fit or sonically welded to the ferrule  20   a . The proximal cover  20   b  includes an interior locking groove  20   c  and a proximal opening  20   d . The push-button  22  has a T-shaped profile with an annular groove  22   a  at the wider distal end and a central bore  22   b  which extends from the distal end to the string hole(s)  30 . A locking ring  21  is placed in the annular groove  22   a . The proximal end of the pushrod  18  is provided with an annular groove  18   b  which receives a thrust washer  23 . 
     As seen best in  FIG. 10 , the narrow proximal part of the push-button  22  extends out of the proximal opening  20   d  of the cover  20   b  and the locking ring  21  frictionally engages the interior wall of the cover  20   b . The proximal end of the pushrod extends into the central bore  22   b  of the push-button  22  and is prevented from passing through the push-button by the thrust washer  23 . From the foregoing, it will be appreciated that the push-button may be moved from the position shown in  FIG. 10  downward until it reaches the top of the ferrule  20   a  which prevents further downward movement. When the push-button  22  is fully depressed, the locking ring  21  engages the locking groove  20   c  and prevents the button from moving proximally. 
     Turning now to  FIGS. 1 and 2 , the initial state of the retractor  10  has the push-button  22  in the proximalmost position with the swivel  24  coupled to the pushrod as previously described and the proximal end of the swivel embraced by (i.e. inside) the distal end  16  of the tube  12 . It will be appreciated that in this state, the string  26  lies in the surface groove  24   f  of the swivel so that the string is not pressed between the swivel and the tube  12 . 
     According to this embodiment, the conical tip  24   a  of the swivel  24  is not sharp enough to pierce the skin. Therefore, the first step in using the retractor is to make a small incision in the chest wall  1  ( FIG. 2 ) between ribs  2 . The retractor  10  is then inserted through the incision as shown in  FIG. 2 . The conical tip  24   a  of the swivel is sharp enough to puncture the pericardium  3  as shown in  FIG. 4 . 
     After the pericardium is pierced, the push-button  22  is depressed as shown in  FIGS. 3 and 4 . This causes the pushrod  18  to move distally out of the tube  12  causing the swivel to move out of the tube as well. At this point, the key  18   a  of the push-rod  18  is still engaging the keyway  24   e  of the swivel  24 . With the instrument configured in this manner, the string  26  which is attached to the middle of the swivel is pulled as shown in  FIGS. 5 and 6 . Because the string  26  extends on the opposite side of the swivel  24  from the T-shaped key  18 , this causes the swivel  24  to “swivel” off the T-shaped key  18   a  at the distal end of the pushrod  18 . When the string  26  has been pulled tight, the keyway  24   e  of the swivel  24  is no longer coupled to the key  18   a  of the pushrod  18 . 
     Preferably, the tube  12  and pushrod  18  are then lifted out of the pericardium, away from the swivel  24  as shown in  FIGS. 7 and 8 . When this is done the swivel  24  remains inside the pericardium  3  as shown in  FIG. 8 . Pulling on the string  26  will retract the pericardium  3  because the swivel will remain substantially perpendicular to the string  26  and the axis of the incision in the pericardium  3 . The pericardium may be held in the retracted position by clamping the string  26  with a hemostat or similar clamp. 
     When surgery is complete or when it is no longer necessary to retract the pericardium, the string  26  is released and the string  28  which is attached to the proximal end of the swivel  24  is pulled as shown in  FIG. 9 . This allows the swivel to be removed from the pericardium  3  and the chest  1  because the swivel will assume a direction coaxial to the string  28  and to the axes of the incisions in the pericardium and chest wall. 
     Particular features and advantages of the first embodiment include the following. The deployment, use and removal of the swivel is very simple and effective. The keyed connection between the pushrod and the swivel prevents the separation of the two until the push-button is pressed. It also prevents the axial rotation of the pushrod relative to the swivel or vice versa, which could cause the strings to become entangled. The locking feature of the push-button assures that the practitioner will always know whether the swivel has been deployed. Unlike some known endoscopic retractors, the retractor of the invention only requires one entry site to deploy and remove. The point at the end of the swivel is sharp enough to pierce the pericardium (i.e. blunt dissection) but blunt enough to protect other tissues. 
     As mentioned above, it is preferable that the two strings  26 ,  28  be easily distinguishable from each other. This may be accomplished by color coding or by labeling. 
     A second embodiment of the invention is illustrated with no proximal actuator in  FIGS. 13-21 . From the following description, those skilled in the art will appreciate how the second embodiment can be used with the same proximal actuator  20 ,  22  shown in the previous Figures or used as shown. 
     Referring now to  FIGS. 13 and 14 , the second embodiment  110  includes a hollow tube  112  having a proximal end  114  and a distal end  116 . A pushrod  118  extends through the tube  112 . In this embodiment, the pushrod  118  is not hollow but has a pair of surface grooves  118   a ,  118   b . A swivel  124  is removably mounted on the distal end  116  of the tube  112 . A pair of strings  126 ,  128  extend from the swivel  124  through the tube  112  along the grooves  118   a ,  118   b  in the pushrod  118 . As seen in  FIG. 14 , the strings  126 ,  128  are actually a single string looped around a centrally located pin  131  in the swivel  124 . 
     The distal portion of the swivel  124  has a sharp distal end  124   a  which is shaped like the point of a trocar (seen best in  FIG. 21 ) and a shoulder  124   b . The proximal end of the swivel has a surface groove  124   c  and a throughbore  124   d  which extend substantially half way to the distal end. A safety shield  125  having a distal shoulder  125   a  and a pair of longitudinal slots  125   b ,  125   c  is mounted over the distal end of the swivel with a spring  127  biased between the shoulders  124   b  and  125   a . A diametrical pin  129  extends through the swivel proximal of the shoulder  124   b  and engages the slots  125   b ,  125   c . Those skilled in the art will appreciate that the distal end of the swivel resembles a trocar used to make incisions during endoscopic and laparoscopic surgery. The proximal portion of the swivel is dimensioned to fit partially into the distal end  116  of the tube  112  and the distal portion is dimensioned to have approximately the same outer diameter as the tube  112 . As seen best in  FIG. 16 , the distal end  118   c  of the pushrod  118  is rounded as is the proximal end  124   e  of the swivel  124  which abuts it. 
     From the foregoing, those skilled in the art will appreciate how the second embodiment of the invention is used. Starting with the instrument configured as shown in  FIGS. 13 and 14 , the distal end of the safety shield  125  is pressed against the chest wall between two ribs. The pressure causes the safety shield  125  to be pushed back against the spring  127  exposing the sharp end  124   a  of the swivel  124 . Further pressure punctures the chest wall. When the shield  125  passes into the space between the chest wall and the pericardium, the spring  127  biases the shield  125  back to the safety position shown in  FIGS. 13 and 14 . Advancing the instrument further pierces the pericardium. The function of the shield is to prevent accidental damage to other tissues and to prevent ripping of the pericardium when the swivel is retracted. 
     After the pericardium is pierced, the pushrod  118  is advanced through the tube  112  as shown in  FIGS. 15 and 16  releasing the swivel  124  from the distal end  116  of the tube  112 . With the swivel released, the string  126  is pulled. This causes the swivel to rotate as shown in  FIGS. 15 and 16 . It will be appreciated that the curved surfaces  118   c  and  124   e  facilitate the rotation. 
     When the string  126  is pulled taut, the swivel  124  will assume a position approximately perpendicular to the string  126 . The pushrod  118  may then be withdrawn as shown in  FIGS. 17 and 18 . Retraction of the pericardium is effected in the same way as described above with reference to the first embodiment. 
     When retraction is no longer needed, the swivel  124  is removed by pulling on string  128 . This returns the swivel to a direction substantially collinear with the string  128  and coaxial to the axes of the incisions in the pericardium and the chest wall. 
     Particular features and advantages of the second embodiment include the following. The deployment, use and removal of the swivel is very simple and effective. When both strings are pulled, the surface grooves on the pushrod prevent the axial rotation of the swivel relative to the pushrod, which could cause the strings to become entangled. The retractor only requires one entry site to deploy and remove. The end of the swivel acts as a trocar and thus obviates the need for an incising tool. 
     There have been described and illustrated herein several embodiments of a pericardial retractor. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while a particular proximal actuator has been disclosed, it will be appreciated that many of the advantages of the invention could be achieved without the proximal actuator or with a different proximal actuator. Also, while the tube, pushrod, and the swivel have all been illustrated and described as being substantially cylindrical, it will be recognized that other cross-sectional shapes could be used with similar results obtained. Moreover, while particular configurations have been disclosed in reference to the strings passing through the tube, it will be appreciated that many of the advantages of the invention could be obtained with one or both of the strings remaining outside the tube. In addition, while the invention was designed with the intention that it be used in endoscopic heart surgery, it may be used in other types of minimally invasive surgery. It will also be appreciated that an effective retractor could be made with the central string slightly off the midpoint of the swivel. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed.