Patent Publication Number: US-2015073207-A1

Title: Single-pass endoscopic vessel harvesting

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to harvesting of living vessels for use in grafting, and, more specifically, to a harvesting device for endoscopically removing a vessel in a “no touch” condition with surrounding pedicle of fat and connective tissue. 
     Blood vessels are often dissected from one portion of a living body to be implanted in another portion of the body by a surgical procedure, such as in a coronary artery bypass graft (CABG) or other cardiovascular procedure. An artery or vein is “harvested” (i.e., removed) from its natural location in a patient&#39;s body and reconnected to provide blood circulation elsewhere in the body. Among the preferred sources for the vessels to be used as the bypass graft are the saphenous vein in the leg and the radial artery in the arm. 
     Endoscopic surgical procedures for harvesting a section of a blood vessel (e.g., the saphenous vein) subcutaneously have been developed in order to avoid disadvantages and potential complications of harvesting of the blood vessel by exposing the desired vein section externally through a continuous incision along the leg. The continuous incision for exposing the vein and for introducing the surgical instruments to seal and sever adjoining tissue and side branches of the vessel results in a significant healing process and associated risks. 
     The known minimally-invasive endoscopic techniques employ a small incision for locating the desired vessel and for introducing one or more endoscopic devices into the small incision. For example, typical commercially available products for performing the endoscopic blood vessel harvesting procedure include a number of separate endoscopic devices that are each inserted into the patient. These endoscopic devices include, for example, an insufflation mechanism having plastic tubing to supply air or CO 2  to insufflate the subcutaneous area; an endoscope having a camera and light cables in order to visualize both the dissection and harvesting procedures; a dissector mechanism to dissect or separate the vessel from connective tissues in the body; and a cutting mechanism to sever and seal any side branches from the vessel and then remove the vessel from the body. In certain instances, the combination of mechanisms can be bulky and cumbersome for the clinician performing the vessel harvesting. Also, in certain instances, these mechanisms require that a relatively large diameter wound and cavity be formed within the patient in order to accommodate all the separate mechanisms. 
     Existing harvesting devices have required an intricate and physically demanding procedure to isolate a vessel from surrounding tissue and to cut and coagulate side branches. This required a high level of skill and practice for the person performing the harvesting procedure. Even with good expertise, several potential sources of damage to the harvested vessel remain. Harvesting typically requires multiple passes of one or more separate devices resulting in much contact with the vessel, potentially leading to endothelial damage. To create a sufficient working space and to allow visualization for tissue separation and side branch cutting, significant insufflation is often used. The CO 2  insufflation gas can lead to tissue acidosis, CO 2  embolism, and other complications. The common use of electrocauterization for cutting and coagulating the side branches can result in thermal spreading to the harvested vessel and sometimes also results in side branch stubs that are too short for obtaining a good, leak-proof seal. 
     It has been discovered that improved patency can be obtained for a vein graph if some surrounding tissue is left intact around the desired vessel. However, conventional endoscopic devices have not been capable of maintaining a layer of surrounding tissue over the harvested vessel. 
     SUMMARY OF THE INVENTION 
     The present invention provides a user-friendly device and procedure for endoscopically harvesting a vessel with a surrounding pedicle for use in grafting. Patency of the vessel is improved and trauma is reduced as a result of harvesting with no direct contact with the vessel. The simplified device and procedure achieve successful harvesting with less need for training or specialized skills. 
     In one aspect of the invention, an apparatus is provided for endoscopic harvesting of a vessel from a body. The vessel has an anterior side closest to the skin. A sheath extends in a longitudinal direction with a dissector tip for advancing along the vessel substantially along the anterior side to create a flanking tunnel spaced away from the vessel. A ring-shaped blade is mounted to the sheath and is disposed in a plane substantially perpendicular to the longitudinal direction and proximal of the dissector tip. The blade forms a lateral loop to encircle the vessel from the flanking tunnel and to make a vasiform cut including a pedicle around the vessel as the sheath advances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view of a saphenous vein being harvested from a leg. 
         FIG. 2  shows a prior art dissector isolating a saphenous vein in an endoscopic procedure. 
         FIG. 3  is a partial cross section showing one embodiment of a harvesting device of the invention. 
         FIG. 4  is a side view of a blade member. 
         FIG. 5  is an end view of a blade member. 
         FIG. 6  is a perspective view of a blade member. 
         FIG. 7  is a perspective view of another blade member. 
         FIG. 8  depicts a blade ring about to be put in place around a vessel at an initial incision. 
         FIG. 9  depicts the blade ring after inserting it around a vessel at the initial incision and ready to make a vasiform cut. 
         FIG. 10  is a cross-sectional, subcutaneous view showing a harvested vessel with surrounding pedicle and flanking tunnel during harvesting. 
         FIG. 11  is a longitudinal cross section showing the harvesting of a vessel according to the present invention. 
         FIG. 12  illustrates a dissected pedicle ready for extraction from the body. 
         FIG. 13  is a cross section of a vessel illustrating the typical locations of side branches. 
         FIG. 14  illustrates a turning maneuver for severing and cauterizing a side branch being encountered near an anterior side of the harvested vessel. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , a patient  10  has a saphenous vein  11  within a lower limb  12 . An incision  13  is made directly above vein  11 , and tissue is peeled back from incision  13  to access the vein. Endoscopic instruments have been inserted through incision  13  to separate vein  11  from connective tissue and then to sever and cauterize side branches that extend from vein  11 . A second incision or stab wound  14  is created at a second position on limb  12  so that a second end of vein  11  can be severed. Vein  11  is then extracted through one of the incisions. The entry point or second incision can be placed at various locations along vein  11  as shown at  15 . 
       FIG. 2  shows a prior art dissector rod  20  inserted into a body through a trocar  21  which maintains an opening at incision  13  and provides a seal for insufflation gas. Trocar  21  may be adhesively attached to skin  22 . Subcutaneous tissue  23  is peeled opened using a transparent tip  24  on dissector rod  20  to create an interior cavity  25  around saphenous vein  11 . Insufflation gas may be introduced into cavity  25  (e.g., via appropriate tubing to trocar  21  or via a channel within rod  20 ) in order to maintain visualization of vein  11  via an endoscopic camera provided within dissector  20  as is known in the art. Dissector rod  20  may be removed after exposing vein  11  so that a cutting instrument can be reinserted for cutting and coagulating the side branches. By the time the section of vein  11  is removed, it has been subjected to handling that potentially causes endothelial and/or thermal injury. 
     An improved endoscopic surgical instrument for harvesting a vessel in a single pass and with an intact pedicle around the vessel is shown in  FIG. 3 . A device body or sheath  30  has a handle  31  at one end and a dissector tip  32  at the other end. An endoscope element  33  is contained within a receptacle  34  within sheath  30  having a forward view through tip  32  (i.e., at least a portion of tip  32  is preferably made of a transparent material). Endoscope element  33  has an end connection  35  connected to a monitor and light source as is known in the art. 
     A cutter element  36  assembles into a corresponding groove(s) on sheath  30 . Element  36  has an intermediate section  38  connected at one end to a cutting blade  37  which is positioned proximally of tip  32 . Blade  37  is disposed in a plane substantially perpendicular to the longitudinal direction of sheath  30 , and is the only ultrasonically-active portion of cutter element  36 . At the other end of intermediate section  38 , a connector  39  is provided for coupling to a power source which may preferably be an ultrasonic generator, for example. Other energy sources could also be used. Intermediate section  38  nests together with sheath body  30  in order to provide a generally smooth outer surface of the combined instrument. Preferably, no insufflation port is constructed in the harvester since no CO 2  insufflation is necessary. 
     Blade  37  is ring-shaped and may perform any type of cutting, such as electro-cautery or ultrasonic. In a preferred embodiment, ultrasonic cutting and cauterization may be used. As shown in  FIG. 4 , ring-shaped blade  37  may have a leading edge  40  and a terminal edge  41  made of a piezoelectric material of the type conventionally used in ultrasonic surgical instruments. Signal transmission lines  42  are preferably disposed on intermediate element  38  to couple a desired oscillating signal to the piezoelectric material when cutting is to be performed. By avoiding the generation of any significant heat, thermal spreading to the target vessel is avoided. As shown in the end view of  FIG. 5 , blade  37  preferably forms an incomplete ring resulting in a gap  43  between terminal end  41  and intermediate section  38 . The ring is not complete around the circumference so that the vessel can be loaded within the ring as a first step, resulting in the vessel and surrounding pedicle being centered in the ring. Then the ring and its support/power supply section can be attached to the harvester rod, forming one integral piece that can be manually guided to dissect the vessel/pedicle. 
       FIG. 6  illustrates another embodiment of a ring-shaped blade  45  having an intermediate section  46  transitioning to a curved end  47 . Only curved end  47  is ultrasonically active. Preferably, a variety of sizes and shapes are made available to the user in order to adapt an instrument to the size and/or location of a target vessel being harvested from a particular patient. 
       FIG. 7  shows yet another embodiment of a cutting element  50  having an intermediate section  51  supporting a ring blade  52 . A narrow leading edge of ring blade  52  is comprised of an ultrasonic material  53 A, while an open end  53 B likewise contains the ultrasonic material for performing tissue cutting during initial placement of ring blade  52  around a vessel as described below. 
     As shown in  FIG. 8 , an incision has been made through a skin layer  56  to internal tissue  55  in order to obtain access to a tissue region  60  around a target vessel  57 . An anterior side of vessel  57  (i.e., toward the exterior or skin side) is mostly free of side branches. Thus, a side branch  58  extends deeper into tissue  55  away from the anterior side. A cutting element  61  has a ring blade  62  with an open end  63  which is used to cut beneath target vessel  57  so that ring blade  62  may be placed as a lateral loop encircling vessel  57 . Tissue  60  around vessel  57  is preferably pinched upward with a grasping tool (not shown) in order to facilitate entry of open end  63  along an incision path  64 . Initial placement of ring blade  62  into path  64  may be done prior to or after the installation of cutting element  61  onto the sheath body. 
       FIG. 9  shows ring blade  62  in its initial position around target vessel  57  with ring blade  62  installed onto dissector tip  65 . An endoscope lens  66  incorporated in tip  65  may be used to visualize the tissue around and including target vessel  57 . A tissue section  67  within the perimeter of ring blade  62  makes up a pedicle around vessel  57 . With the device in the initial position shown in  FIG. 9 , vessel  57  remains fully intact (i.e., its end has not yet been cut). By maintaining the integrity of vessel  57  and its surrounding pedicle  67  when blade  62  is advanced, a counter-traction is maintained when tip  65  performs its cutting action along vessel  57  as described below. 
     Once cutting element  61  is assembled onto the sheath body, open end  63  of blade  62  is preferably positioned in an open space inside the general profile of the sheath body. This ensures that all the tissue to be cut is contacted by the active region of the ring. Open end  63  does not actually contact tip  65 , but is instead free to vibrate ultrasonically in response to the energy source. 
     With ring blade  62  encircling target vessel  57  at the initial incision, dissector tip  65  is advanced along the vessel substantially along the anterior side in order to create a flanking tunnel  70  spaced away from vessel  57  as shown in  FIG. 10 . As an operator presses the handle forward and guides dissector tip  65  just slightly above the position of target vessel  57 , a vasiform cut  71  is made encircling a pedicle  67  and vessel  57 . The length of vasiform cut  71  progresses as dissector tip advances for a desired length of vessel to be harvested.  FIG. 11  shows a side view during the formation of a vasiform cut around target vessel  57 . As the operator advances tip  65  above target vessel  57  so as to maintain an amount of connective tissue  55  between tip  65  and vessel  57 , ring blade  67  is energized in order to make the vasiform cut that simultaneously excises pedicle  67  and vessel  57  while automatically severing and cauterizing side branches such as branches  73  and  74 . Thus, only a single pass is needed in order to form the desired pedicle with embedded vessel, thereby resulting in minimal disturbance or injury to target vessel  57 . 
     As shown in  FIG. 12 , once a sufficient length of pedicle  67  containing the target vessel has been made between an initial end  76  and a final end  77 , a second incision  78  is made through skin  56  in order to access final end  77 . A scalpel or other cutting instrument can then be used at each incision in order to sever the ends of pedicle  67  so that the harvested vessel can be removed and the remaining ends of the saphenous vein can be sealed off. Thereafter, instrument  30  may be removed from the patient. 
       FIG. 13  shows a transverse cross-section through vessel  57  and pedicle  67 . An anterior side  83  of vessel  57  is located between radial positions  81  and  82 . This anterior side  83  is generally free from side branches. Nearly all the side branches, such as side branch  58 , are encountered at a non-anterior side  80  between radial positions  81  and  82 . By configuring the ring blade to span non-anterior portion  80  and to have each end of the ring contained within the flanking tunnel, a procedure is obtained wherein most all side branches are automatically cut and cauterized without the operator taking any special actions. In the event that a side branch is encountered along the anterior side as shown in  FIG. 14 , the operator may rotate tip  65  in a direction away from a side branch  58  as shown by arrow  84  in order to avoid contact between dissector tip  65  and branch  58 . This places branch  58  in a position to be cut by the ring blade. As tip  65  advances past the position of side branch  58 , the operator restores the handle to the original orientation, thus bringing tip  65  back to the original anterior side as shown by arrow  85 . 
     Using the foregoing invention, a target vessel can be gently retracted and may be harvested together with a surrounding pedicle that provides protection and life support for the vessel. No CO 2  is needed, although a small amount of CO 2  insufflation may be used if desired, but may be performed at a significantly reduced amount as compared to the prior art. A speed of forward movement of the dissector tip and ring blade may be adjusted by the operator according to any variations in the tissue as they advance. In addition, a magnitude of ultrasonic oscillation can be adjusted by the operator to ensure adequate coagulation and ligation of a range of small to larger side branches. A passive or low suction incorporated in the harvester could also be used in order to remove any desiccation fluid created by the ring activity plus any smoke that may need to be vented. At no point in the inventive procedure is the vessel “skeletonized”. The anterior pass of the dissector tip is steered so that several cell layers of fat and connective tissue remain attached to the vessel. Visualization of the vessel through the thin layers is sufficient to steer the instrument and anticipate the vessel&#39;s path.