Abstract:
An endoscopic vessel harvester includes a vessel keeper for capturing a target vessel within a tunnel that has been dissected along the target vessel. A cutter member cuts and cauterizes side branches while the target vessel is slidably captured in the vessel keeper. A spray nozzle carried by the vessel keeper delivers a preservative fluid via a manual control valve and a conduit. The preservative fluid is sprayed on the target vessel proximate a respective side branch immediately after being cauterized. Thus, a harvested vessel is bathed in preservative fluid prior to being actually removed from the body, enhancing endothelial preservation from cascading events.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates in general to endoscopic harvesting of blood vessels, and, more specifically, to reducing endothelial damage resulting from dissection, cauterizing, and handling of a target vessel. 
         [0004]    In coronary artery bypass grafting (CABG), a blood vessel or vessel section, such as an artery or vein, is “harvested” (i.e., removed) from its natural location in a patient&#39;s body for use as a graft. After removal, the section of blood vessel is joined between an arterial blood source and the coronary artery that is to be bypassed. Among the preferred sources for the vessel to be used as the bypass graft are the saphenous vein in the legs and the radial artery in the arms. 
         [0005]    Endoscopic surgical procedures for harvesting a section of a vessel (e.g., the saphenous vein) subcutaneously have been developed in order to avoid disadvantages and potential complications of older harvesting techniques wherein a continuous incision (e.g., along the leg) was made for the full length of the desired vessel section in order to provide adequate exposure for visualizing the vessel and for introducing surgical instruments to sever, cauterize, and ligate the tissue and side branches of the vessel. One such minimally-invasive technique employs a small incision for locating the desired vessel and for introducing one or more endoscopic harvesting devices. Primary dissection occurs by introduction of a dissecting instrument through the incision to create a working space and to separate the vessel from the surrounding tissue. Then a cutting instrument is introduced into the working space to sever the blood vessel from the connective tissue surrounding the section to be harvested and any side branches of the blood vessel. The branches may be clipped and/or cauterized. 
         [0006]    In one typical procedure, the endoscopic entry site is located near the midpoint of the vessel being harvested, with dissection and cutting of branches proceeding in both directions along the vessel from the entry site. In order to remove the desired section of the blood vessel, a second small incision, or stab wound, is made at one end thereof and the blood vessel section is ligated. A third small incision is made at the other end of the blood vessel section which is then ligated, thereby allowing the desired vessel section to be completely removed through the first incision. Alternatively, only the first two incisions may be necessary if the length of the endoscopic device is sufficient to obtain the desired length of the blood vessel while working in only one direction along the vessel from the entry point. 
         [0007]    An example of a commercially available product for performing the endoscopic vessel harvesting described above is the VirtuoSaph™ Endoscopic Vein Harvesting System from Terumo Cardiovascular Systems Corporation of Ann Arbor, Mich. Endoscopic vessel harvesting systems are described in U.S. Pat. No. 8,465,488 to Maeda et al and U.S. Pat. No. 7,547,314 to Kadykowski, both of which are incorporated herein by reference in their entirety. After harvesting, the vessel is inspected and prepared for surgery by checking for leaks or other defects. The prepared vessel is then stored in a preservative fluid until needed. U.S. Pat. No. 8,123,672 discloses a kit for preparing and preserving a blood vessel for bypass graft surgery. 
         [0008]    In the VirtuoSaph™ System, the cutting tool for severing and cauterizing branches has the form of a V-cutter wherein a V-shaped tip at the distal end of the cutter guides a branch to be cut into a longitudinal slit. Electrodes adjacent the slit are electrically energized with a high frequency voltage in order to cauterize and sever the branch by coagulation. Unfortunately, a cascade of biochemical events within the tissue can affect the endothelium. It would be advantageous if the cascade of events could be minimized with respect to the endothelium in order to improve the long term patency of vessels used as coronary artery bypass grafts. 
       SUMMARY OF THE INVENTION 
       [0009]    In one aspect of the invention, an endoscopic vessel harvester comprises a longitudinal insertion member having a proximal end with a handle and a distal end adapted for insertion into a tunnel dissected along a target vessel within a body of a patient. A vessel keeper is extendably mounted at the distal end of the insertion member comprising a capture frame with a movable side having an opened position to admit the target vessel and having a closed position to slidably capture the target vessel. A cutter member is extendably mounted at the distal end of the insertion member having a cauterizing element adapted to contact side branches of the target vessel and to cut and cauterize the side branches while the target vessel is slidably captured in the vessel keeper. A spray nozzle is carried by the vessel keeper. A preservative distributor includes a manual control valve and a conduit between the valve and the spray nozzle adapted to deliver a preservative fluid to the target vessel proximate a respective side branch immediately after being cauterized. Thus, a harvested vessel is bathed in preservative fluid prior to being actually removed from the body, lessening endothelial damage arising from cascading biochemical events. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side view of a vessel harvester of the invention. 
           [0011]      FIG. 2  is a top view of the distal end of the vessel harvester. 
           [0012]      FIG. 3  is a perspective view of the distal end of the harvester. 
           [0013]      FIG. 4  is an endoscopic view of the harvester inside the body of a patient during harvesting of a vessel. 
           [0014]      FIG. 5  is a perspective view of the cutter member and an irrigator for flushing debris from the cutter member. 
           [0015]      FIG. 6  is an end view of the embodiment of  FIG. 5 . 
           [0016]      FIG. 7  is a block diagram showing the shared supply of preservative fluid for bathing the target vessel and flushing the cutter member. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]      FIG. 1  shows a harvester rod  10  used to grasp the target vessel being dissected and to sever any branches or connective tissue connecting to the vessel. Harvester rod  10  is inserted into a working tunnel along a target vessel that is created using a dissector rod (not shown). Harvester rod  10  has a handle  11  connected to an elongated sleeve member or insertion member  12  and to an endoscope receiver  13 . At the distal end of insertion member  12  are a vessel-keeper (V-keeper)  14  which is a capture frame for retaining the vessel being dissected and a V-cutter  15  for severing side branches and connective tissue. V-keeper  14  is manipulated by V-keeper buttons  16  on handle  11 . V-cutter  15  is extended or retracted by manipulating a V-cutter extender button  17  on handle  11 . An endoscope wiper lever  18  may be provided on handle  11  for controlling a wiper that clears the end of the endoscope when the endoscope optics become covered by material from the body cavity. An insufflator tube  20  can be connected to a source of gas such as CO 2  to deliver insufflation gas to the distal end of insert member  12 . A bipolar cord  21  has a connector  22  at one end for connecting to a source of high frequency voltage, and includes conductors for supplying the voltage to electrodes on V-cutter  15 . 
         [0018]    V-keeper  14  and V-cutter  15  are shown in greater detail in  FIG. 2 . V-keeper  14  includes a guide frame  25  mounted to a support rod  26  and a movable rod  27 . Guide frame  25  and rod  27  together form the capture frame with an internal opening  28 . The vein or other vessel to be harvested is maneuvered into opening  28 , and then the V-keeper buttons on the handle are manipulated to extend rod  27  along one side of the capture frame in order to close opening  28  and thereby retain the vessel. V-cutter  15  includes a V-tip  30  with a central slit mounted to an extendable guide  31  that is manipulated by the V-cutter button on the handle in order to place side branches into the slit. 
         [0019]      FIG. 3  shows the distal end of harvester rod  10  in greater detail. V-keeper  14  is longitudinally extendable as shown by arrow  37  while rod  27  is independently longitudinally extendable as shown by arrow  38 . In  FIG. 3 , rod  27  is in an extended position used for maintaining the vessel being harvested within opening  28  (i.e., the side of the capture frame is closed). 
         [0020]    V-cutter  15  is longitudinally extendable in the directions shown by arrow  39 . Elongated insertion member  12  has a notch  40  with a terminal edge  41  which exposes V-cutter  15  prior to being extended further than the end of insertion member  12 . A guard piece  42  is provided beneath V-cutter  15 . A lens portion  43  at the end of the endoscope is shown positioned near the distal end of member  12 . A wiper  44  is mounted for pivoting over lens  43  as controlled by lever  18  ( FIG. 1 ) to wipe away debris from lens  43 . 
         [0021]    In the illustrated embodiment of  FIGS. 1-3 , the invention provides distribution of a preservative fluid in the region of V-keeper  14  so that, after a cauterizing event, the preservative fluid can be delivered to the target vessel proximate to the cauterized area. The fluid locally bathes the target vessel, not only resulting in cooling of the vessel but also minimizing the usual cascade of biochemical events that affect the endothelium even before the vessel is removed from the body. Since the fluid would interfere with cauterization, it is only delivered after cauterization is complete at each particular position along the length of the vessel. 
         [0022]    As shown in  FIGS. 2 and 3 , a spray nozzle  50  receives preservation fluid via a fluid conduit  51  passing through frame  24  and rod  26 . Nozzle  50  may be comprised of any suitable type of fluid exit with or without features for atomizing or otherwise dispersing an outflow of preservation fluid. By locating nozzle  50  on frame  25  (preferably oriented to spray fluid toward opening  28 ), the spray can be easily directed to a desired portion of the target vessel which is captured within opening  28 . Thus, after V-cutter  15  has been energized to cauterize a side branch, V-keeper  14  is put into a position from which the preservative fluid spraying out from nozzle  50  will bathe the target vessel in an area proximate to where the cauterization has occurred. The preservative fluid may preferably be a biocompatible aqueous solution such as an isotonic saline solution. The saline solution may be lactated (such as with a lactated Ringer&#39;s solution) or may include medications (such as with a papaverine solution). Solutions other than saline can also be used, such as a potassium-chloride solution. 
         [0023]      FIG. 4  is an endoscopic view as seen during vessel harvesting wherein a target vessel (e.g., saphenous vein)  55  is retained within opening  28  of V-keeper  14  within a cavity around vessel  55  created previously during blunt dissection. V-cutter  15  is in position for extending toward a side branch  56  for cauterizing and severing it to prepare a section of vessel  55  for removal. After cauterizing and severing branch  56 , V-keeper frame  25  is positioned to align spray nozzle  50  alongside vessel  55  proximate to cauterized branch  56 , and a supply of preservative fluid is activated in order to deliver a fluid spray  57 . Besides a cooling effect provided by the fluid, preservation of the functioning of the endothelium is initiated much sooner than in the prior art which did not apply any preservative until the target vessel was removed from the body. 
         [0024]      FIGS. 5 and 6  show a further embodiment of the invention wherein a fluid supply is simultaneously used within the harvester for the purpose of clearing debris from the V-cutter. Thus, an irrigator nozzle  61  is mounted to insertion member  12  at notch edge  41 . Nozzle  61  is in longitudinal alignment with a slit  60  in V-cutter  15  for dispensing a fluid to clean slit  60  when V-cutter  15  is moved to the inward position.  FIG. 6  shows an end view wherein nozzle  61  is located directly above slit  60 . Preferably, nozzle  61  may be oriented to direct discharged fluid slightly downward in the figure. 
         [0025]      FIG. 7  shows V-cutter  15  retracted to its inward position facilitating the flow of fluid in a jet from nozzle  61 . A fluid distribution system is provided for sharing a supply of pressurized preservative fluid from a supply tank  65 . Aqueous fluid is delivered to V-keeper spray nozzle  50  ( FIGS. 2-4 ) by fluid conduit  51  passing through insertion member  12  from a first manually-controlled valve  66  which is connected to tank  65 . In parallel, irrigation nozzle  60  receives the aqueous fluid via a fluid conduit  62  passing through insertion member  12 . Conduit  62  selectably receives fluid via a second manually-controlled valve  67  connected to tank  65 . Tank  65  may preferably include a pump (not shown) for outputting a flow of saline solution to selectably generate sprays from nozzles  50  and  61 . The pump and valves  66  and  67  are operator controlled to coordinate creation of the spray with proper positioning of the V-keeper and/or the V-cutter. 
         [0026]    During an endoscopic procedure to harvest a vessel, the endoscopic vessel harvester is inserted into the body alongside the vessel to be harvested. The cutter is extended and the electrodes are energized (e.g., by a foot pedal operated by a surgeon) to individually sever a plurality of branches. Periodically (e.g., after each cauterizing event), valve  66  is manually activated in order to bathe the target vessel with preservative fluid in the area proximate to the severed branch(es). Repeated cutting operations may result in a buildup of debris in the longitudinal slit. The cutter is then retracted to a position longitudinally inward from its cutting position while maintaining the endoscopic vessel harvester in the body so that the debris may be cleared from the longitudinal slit by manually activating valve  67  to deliver a spray that flushes away the debris.