Patent Publication Number: US-2015088172-A1

Title: Vascular anastomosis device and vascular anastomosis method

Description:
TECHNICAL FIELD 
     The present invention relates to a vascular anastomosis device, which is a device for connecting and conglutinating two blood vessels with different diameters. 
     BACKGROUND ART 
     Conventionally, for connecting and conglutinating two blood vessels, suturing or anastomosis using an anastomosis device has been performed. In the cases where the two blood vessels have different diameters, however, the only option is suturing. For anastomosis of blood vessels with different diameters, it is necessary that the two end surfaces to be coupled be made identical in size. For the purpose, as shown in  FIG. 1A , an incision  2  is made in the longitudinal direction from the end surface of the small-diameter blood vessel  1 . Then, as shown in  FIG. 1B , the small-diameter blood vessel  1  is opened so as to fit the size of the end surface of the large-diameter blood vessel  3 . After that, as shown in  FIG. 1C , the blood vessels  1  and  3  are sutured in the state where the end surfaces are joined together. However, connecting and conglutinating blood vessels by suturing has a disadvantage of taking immense amount of time and effort. 
     To overcome the disadvantage, an anastomosis device for anastomosing blood vessels by separately inserting blood vessels through truly circular rings with pins, pulling outward the end portion of each vessel and impaling it on the pins, and joining the two rings together was developed (refer to Non Patent Literature 1). Referring to  FIG. 2 , anastomosis using a conventional vascular anastomosis device will be described. After a blood vessel end portion  4   a  held with forceps  9  is inserted through a truly circular ring  5  as shown in  FIG. 2A , a vascular wall  6  is extended outward 90 degrees and impaled on pins  7  as shown in  FIG. 2B . The other blood vessel is also treated in the same manner. Next, as shown in  FIG. 2C , while the two rings  5  are moved closer to each other, the knob (not shown) of the anastomosis device is turned to introduce the two rings  5  into the guide slit  8 . Thus the rings  5  are joined together as shown in  FIG. 2D . Further, as shown in  FIG. 2E , the rings  5  are tightly clamped with forceps  9  so that the rings are completely joined. After that, further turning the knob allows a protrusion  8   a  (refer to  FIG. 2C ) to advance into the guide groove  10   b  provided on the guide plate  10   a  shown in  FIG. 2B  (refer to the arrow direction AD in  FIG. 2E ) and push the rings  5  so that the rings  5  are released from the anastomosis device  10 . A pair of tweezers  9   a  is used for holding the blood vessel  4 . 
     In the cases where blood vessels with almost the same diameters are subjected to anastomosis, the anastomosis device shown in  FIG. 2  can be used satisfactorily. However, since the conventional anastomosis device as shown in  FIG. 2  uses two truly circular rings, the device has disadvantages shown below in connecting blood vessels with different diameters. That is, if rings suitable for the large diameter blood vessel are used, the small-diameter blood vessel needs to be forcibly adapted to the large ring, which can result in unsuccessful anastomosis due to wall tearing of the small-diameter blood vessel. Conversely, if rings suitable for the small-diameter blood vessel are used, anastomosis will be impossible due to too loose fitting for the large-diameter blood vessel. 
     CITATION LIST 
     Non Patent Literature 
     Non Patent Literature 1: 
     
         
         Kiso to Rinsho (The Clinical Report) “ Bishoukekkann hunngouki ‘Precise’ shiyousha no shugiteki tekiou ni kannsuru ichi kousatsu  (Technical Indications for Surgeons of Microvascular Anastomotic Device ‘Precise’)”, 27(13): 5393-5397, 1993, 319-323 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The present invention was made in view of such a problem of the prior art, and an objective thereof is to provide a vascular anastomosis device and a vascular anastomosis method which enable favorable anastomosis of blood vessels with different diameters. 
     Solution to Problem 
     To solve the above problem, the present invention utilizes the suturing shown in  FIG. 1B . That is, the present inventor focused attention on the fact that, in the suturing where the small-diameter blood vessel  1  is opened so as to fit the size of the end surface of the large-diameter blood vessel  3 , the end surface of the small-diameter blood vessel becomes elliptical in shape. In the present invention, in the cases where blood vessels are anastomosed using the rings as shown in  FIG. 2 , a flexible material is employed as the material for the ring through which the small-diameter blood vessel is inserted and the ring through which the large-diameter blood vessel is inserted. Hereinafter, the concept of the vascular anastomosis method using the vascular anastomosis device of the present invention will be described referring to  FIGS. 3A to 3F . 
     First, as shown in  FIG. 3A , a ring  11   a , which has pins and is suitable for the large-diameter blood vessel, is selected and the end portion of the large-diameter blood vessel  12  is inserted through the ring. Then, as shown in  FIG. 3B , the vascular wall  13  is extended outward 90 degrees and impaled on the pins  14 . Next, as shown in  FIG. 3C , the end portion of the small-diameter blood vessel  15  is inserted through the ring  11   b , which has pins and is of the same size as the above ring  11   a . As shown in  FIG. 3D , the ring  11   b  is elliptically deformed so that the minor axis agrees with the diameter of the small-diameter blood vessel, and an incision  16  is made in the longitudinal direction from the end surface of the small-diameter blood vessel  15 . Further, the ring  11   a  shown in  FIG. 3B  is deformed into the elliptical shape of the ring  11   b  shown in  FIG. 3D . Then, as shown in  FIG. 3E , the small-diameter blood vessel  15  is elliptically opened, and the vascular wall  17  is extended outward 90 degrees and impaled on pins  18 . Subsequently, the two rings  11   a  and  11   b  are joined together as shown in  FIG. 3F  so that the large diameter blood vessel  12  and the small-diameter blood vessel  15  are anastomosed. 
     That is, the vascular anastomosis device of the present invention is a vascular anastomosis device for anastomosing two blood vessels with different diameters, characterized in that the device comprises a first ring with pins and a second ring with pins both made of a material which is deformable by an external force and allows the pins to stick thereinto, and an openable ring holder, which is made of a pair of components, detachably holds the first ring and the second ring, and has a means for deforming the rings with pins, and that vascular anastomosis can be achieved in the following manner: the ring holder holding the rings is opened, the end portion of the large-diameter blood vessel is inserted through the first ring and the vascular wall is extended outward 90 degrees and impaled on the pins, the end portion of the small-diameter blood vessel is inserted through the second ring, an incision is made in a longitudinal direction from the end surface of the small-diameter blood vessel, the first ring and the second ring are deformed into a same elliptical shape by the means for deforming the rings so that the minor axis agrees with the diameter of the small-diameter blood vessel, the small-diameter blood vessel is elliptically opened and the vascular wall is extended outward 90 degrees and impaled on the pins, and the first ring and the second ring are joined together to allow the pins provided on the ring in one component to stick into the ring in the other component and anastomose the large-diameter blood vessel and the small diameter blood vessel. 
     In addition, the vascular anastomosis method of the present invention is a vascular anastomosis method for anastomosing two blood vessels with different diameters, characterized in that a first ring with pins and a second ring with pins both made of a material which is deformable by an external force and allows the pins to stick thereinto are provided, and that the end portion of the large-diameter blood vessel is inserted through the first ring and the vascular wall is extended outward 90 degrees and impaled on the pins, the end portion of the small-diameter blood vessel is inserted through the second ring, an incision is made in a longitudinal direction from the end surface of the small-diameter blood vessel, the first ring and the second ring are deformed into a same elliptical shape by a means for deforming the rings so that the minor axis agrees with the diameter of the small-diameter blood vessel, the small-diameter blood vessel is elliptically opened and the vascular wall is extended outward 90 degrees and impaled on the pins, and the first ring and the second ring are joined together to allow the pins provided on the ring in one component to stick into the ring in the other component and anastomose the large-diameter blood vessel and the small diameter blood vessel. 
     Advantageous Effects of Invention 
     By using the vascular anastomosis device and the vascular anastomosis method of the present invention, blood vessels with different diameters can be anastomosed. Since the rings with pins are made of a material which is deformable by an external force and allows the pins to stick thereinto, vascular obstruction due to collapse can be prevented and flexible expansion can be achieved when blood flow is increased. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A to 1C  are figures for illustrating a vascular anastomosis method by hand suturing. 
         FIGS. 2A to 2E  are figures for illustrating a vascular anastomosis method using a conventional vascular anastomosis device. 
         FIGS. 3A to 3F  are figures for illustrating the concept of the vascular anastomosis method using the vascular anastomosis device of the present invention. 
         FIG. 4  is a perspective view showing an embodiment of the vascular anastomosis device of the present invention. 
         FIG. 5  is a perspective view for illustrating uncapping of the cartridge at the tip of the vascular anastomosis device of the present invention. 
         FIG. 6A  is a perspective view showing Example 1 of the vascular anastomosis device of the present invention, and  FIG. 6B  is a partial plan view showing the connection diagram of the shaft portion as the rotation center of the cartridge of  FIG. 6A . 
         FIG. 7A  is a perspective view showing Example 2 of the vascular anastomosis device of the present invention, and  FIG. 7B  is a partial plan view showing the connection diagram of the shaft portion as the center of the cartridge of  FIG. 7A . 
         FIG. 8A  is a perspective view showing Example 3 of the vascular anastomosis device of the present invention, and  FIG. 8B  is a partial plan view showing the connection diagram of the shaft portion as the rotation center of the cartridge of FIG.  8 A. 
         FIGS. 9A and 9B  are views showing a modification example of  FIGS. 8A-8C . 
         FIG. 10A  is a front view showing the pin shape in a conventional ring with pins, and  FIGS. 10B and 10C  are front views showing separate examples of the ring with pins of the present invention. 
         FIG. 11A  is a plan view of an example of the ring with pins of the present invention, and  FIG. 11B  is a sectional view along arrows B-B in  FIG. 11A . 
         FIG. 12  is a perspective view showing another example of the ring with pins of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described. Needless to say, other embodiments can also be used without departing from the scope of the invention. 
     (1) Shape of Ring 
     The ring before deformation may be truly circular or elliptical, and needs to be flexible. When two blood vessels with different diameters are anastomosed, the diameter of the rings needs to fit the larger blood vessel. If the diameter of the rings is smaller than that of the larger blood vessel, anastomosis will be impossible due to too loose fitting for the large-diameter blood vessel. Conversely, if the diameter of the rings is too large, the small-diameter blood vessel needs to be forcibly adapted to the large ring, which can result in wall tearing of the small-diameter blood vessel. As mentioned above, the rings are deformed into an elliptical shape. As will be described later in the section of Deformation Mechanism, there is a possibility that efficient joining of the two rings cannot be achieved due to ring slippage that can occur while a predetermined force for elliptical deformation is transmitted to the ring. For efficient force transmission to both sides of each ring, and for the prevention of slippage or falling of the ring during the deformation, it is recommended that the flat surface  74  perpendicular to the direction of the force is provided on the outer side surface of the ring, as shown in  FIG. 12 . In the present invention, the term ellipse includes not only mathematically defined ellipses (the set of points such that the sum of the distances to two fixed points (the foci) is constant) but also wide variety of ovals (shapes like a circle, but wider in one direction than the other). 
     Next, the dimension of the rings will be described. The dimension and the shape of the rings used in the present invention are not particularly limited and a ring of any size and shape may be used as long as vascular anastomosis can be efficiently achieved using the rings. However, since blood vessels with different diameters are anastomosed in the present invention, the rings need to have a flange-like shape and a diameter which fits the large-diameter blood vessel, as described above. In this view, commercially available standard rings can be used, but other rings than those in the standard range are also usable in principle. It is recommended that, in the cases where elliptical rings are used, the rings have such a diameter that the long-diameter blood vessel can effortlessly be inserted therethrough. In particular, regarding commercially available ordinary rings for anastomosing blood vessels of the same diameter, those having inner diameters of 1.0 to 3.0 mm are widely used, and in the present invention as well, the inner diameter (in the case of an ellipse, the inner shorter diameter; hereinafter referred to as the “inner minor axis”) may be suitably used as described above. However, the vascular anastomosis device of the present invention can also be applied to larger blood vessels, for example the human aorta, of which the diameter is 40 mm or more. Too fine blood vessels (for example, capillaries) cannot be anastomosed or do not need anastomosis in principle. Therefore, the range of the ring inner diameter (in the case of an elliptic ring, the inner minor axis) of 0.3 to 50 mm is sufficient for most human blood vessels. When applied to the anastomosis of blood vessels of large animals, further larger inner diameters may be used. The width of the ring flange (half of the difference between the outer diameter and the inner diameter) is also not particularly limited, and any ring having a similar flange width to that of a commercially available conventional ring can be used without any problem. However, it is recommended that the flange width is determined as appropriate depending on the diameter of the blood vessel to be inserted and the shape of the pins. Specifically, the generally recommended flange width of the ring is about 0.3 to 10 mm. 
     Further, the thickness of the rings used in the present invention is not particularly limited and has only to allow the pins provided on one ring to stick into the other ring when the rings are joined and to prevent the pins from being easily pulled out. Specifically, when applied to human blood vessels as described above, the recommended thickness is 0.3 to 20 mm, in particular 0.5 to 10 mm. When applied to blood vessels with larger diameters, for example to blood vessels of large animals, the thickness may be more. 
     As will be described later, the ring body of the present invention made of a flexible material may be thicker and the pins may be longer, as compared to conventional commercial rings and pins, to some degree in order that pins are more securely caught in the opposing ring in the joined state of the rings. Too long pins will stick through the opposing ring and protrude from the other side, causing problems. Too small dimensions (including the thickness) of the rings can prevent efficient vascular anastomosis and too large dimensions can cause adverse effects on the patient after operation. 
     (2) Flexible Materials 
     The rings generally used for conventional anastomosis devices are made of polyethylene resins, which are not flexible. Materials that can be used for the rings of the present invention are deformable by an external force and allow the pins to stick thereinto, and as such materials, flexible materials can be used. The materials preferably have biocompatibility as well. Specific examples of the materials that can be used for the rings of the present invention include a silicone resin, a natural rubber, a synthetic rubber, a flexible epoxy resin, a thermoplastic elastomer, an aliphatic polyurethane, a polyether block amide copolymer, and a flexible fluororesin. However, materials usable in the present invention are not limited to these. It is preferable that the ring made of such a flexible material easily deforms when a predetermined force is applied, and it is more preferable that the ring can be restored to the original shape when the force for deformation is removed. The reason is that, in the course of anastomosis of blood vessels with different diameters, even if the force for deformation is so strong that the ring deforms into an unfavorable shape, removal of the force restores the ring to the original shape, allowing another deformation. 
     (3) Ring Deformation Mechanism 
     Overall Configuration 
       FIG. 4  is a perspective view showing an embodiment of the vascular anastomosis device of the present invention. The vascular anastomosis device comprises two identical rings with pins  21  made of a flexible material, an openable ring holder  22 , which detachably holds the rings with pins  21 , and a sliding mechanism comprising a cylinder  23  for supporting the ring holder  22  so as to allow the ring holder to move back and forth, and a rotary knob  24 . The ring holder  22  may have a wide variety of means for deforming the rings as will be described later. While the two rings  21  are brought closer to each other by closing movement of the ring holder  22 , the rotary knob  24  is turned to introduce the two rings  21  into the guide slit  25   b  and join the two rings  21 . After that, further turning the rotary knob  24  allows the support bar  25  to extend so that the protrusion  25   a  advances into the guide groove  22   a  provided on the ring holder  22  and pushes the rings  21  so that the rings  21  are released from the ring holder  22 . 
     Example 1 
     A locking hook (not shown) provided on the cylinder  23  is engaged in the slot  27  of the cap  26 , and thereby the cartridge at the tip of the vascular anastomosis device is protected with the cap  26 , as shown in  FIG. 5 . The cap  26  is pinched between fingers and removed.  FIG. 4  shows the state where the cap  26  has been removed in this way. The arrows AR in  FIG. 5  show the insertion direction of the cartridge at the tip of the vascular anastomosis device into the cap  26 . 
     As shown in  FIG. 6A , the cartridge comprises a pair of right and left components  28   a  and  28   b . The components  28   a  and  28   b  are held around the shaft with use of a spring  29 , and therefore, when the cap  26  is removed, the spring force opens the cartridge. The ring  31  held by the ring holder  30  in the cartridge component  28   a  is, as shown in  FIG. 6B , subjected to a force in the direction toward the fixed retainer plate  35  due to the resilience of the spring  34  held between the outer frame  32  and the movable retainer plate  33 . Inside the movable retainer plate  33 , a tapered threaded portion  36  is provided. There is no intention to provide detailed description, but the other cartridge component  28   b  has the same configuration, that is, comprises the ring holder  30 , the ring with pins  31 , the outer frame  32 , the movable retainer plate  33 , the spring  34 , the fixed retainer plate  35 , and the tapered threaded portion  36 . 
     The diameter of the rings  31  fits the large-diameter blood vessel. The large-diameter blood vessel is inserted through either of the right and left rings  31  and the vascular wall is impaled on the pins of the ring, as shown in  FIG. 3B . 
     The shaft as the rotation center of the cartridge is, as shown in  FIG. 6B , provided with a tapered threaded portion  38  which screws with the tapered threaded portion  36 . The tip of the rotatable driver  39 , which passes through the bar  37  (refer to  FIG. 6A ) held by the cylinder  23  (refer to  FIG. 4 ), is capable of engaging with the protrusion  40  provided at the end of the threaded portion  38 . 
     Next, the small-diameter blood vessel is inserted through the other ring  31 , and the tip of the driver  39  is rotated in an engaged state with the protrusion  40  to move the threaded portion  38  in the upward direction in the figure. As a result, the movable retainer plate  33  is subjected to a force in the direction toward the fixed retainer plate  35  due to the resilience of the spring  34 , and the ring  31  is deformed into an elliptical shape. The driver  39  is continuously moved until the minor axis of the deformed rings  31  corresponds to the diameter of the small-diameter blood vessel. Since the deformation of the rings  31  by the operation of the driver  39  occurs in the same manner in both the right and left cartridge components, the two rings  31  are deformed into the same elliptical shape. Then, an incision is made in a longitudinal direction from the end surface of the small-diameter blood vessel, the small-diameter blood vessel is elliptically opened, and the vascular wall is extended outward 90 degrees and impaled on the pins (refer to  FIGS. 3C to 3E ). In this case, the operation of the driver deforms the two rings simultaneously and to the same degree. 
     The right and left cartridge components  28   a  and  28   b  are joined to allow the pins provided on the ring in one component to stick into the ring in the other component. Thus, the vascular anastomosis is completed (refer to  FIG. 3F ). After that, the driver  39  is moved in the downward direction in the figure to reduce the resilience of the spring  34  until the driver is returned to its original position. Further, as described in paragraph [0018], turning the rotary knob  24  shown in  FIG. 4  allows the support bar  25  to extend so that the protrusion  25   a  advances into the guide groove  30   a  provided on the ring holder  30  shown in  FIG. 6A  and pushes the rings  31  so that the rings  31  are released from the ring holder  30 . In order that the amount of movement of the driver  39  could be checked from the outside, an appropriate scale mark is preferably provided on the outside of the cylinder  23  (refer to  FIG. 4 ). It is preferable that the screws or the like, which will be described later, are also provided with something equivalent to the scale mark. 
     Example 2 
     As described above, the cartridge at the tip of the vascular anastomosis device is protected with a cap, which is to be removed in the same manner as above. 
     As shown in  FIG. 7A , the cartridge comprises a pair of right and left components  41   a  and  41   b . The components  41   a  and  41   b  are held around the shaft with use of a spring  42 , and therefore, when the cap is removed, the spring force opens the cartridge. The ring  44  held by the ring holder  43  in the cartridge component  41   a  is, as shown in  FIG. 7B , subjected to a force in the direction toward the fixed retainer plate  49  against the resilience of the spring  48  when the thread  46  passing through the outer frame  45  presses the movable retainer plate  47 . There is no intention to provide detailed description, but the other cartridge component  41   b  has the same configuration, that is, comprises the ring holder  43 , the ring with pins  44 , the outer frame  45 , the thread  46 , the movable retainer plate  47 , the spring  48 , and the fixed retainer plate  49 . 
     The diameter of the rings  44  fits the large-diameter blood vessel. The large-diameter blood vessel is inserted through either of the right and left rings  44  and the vascular wall is impaled on the pins of the ring, as shown in  FIG. 3B . 
     Next, the small-diameter blood vessel is inserted through the other ring  44 , and the movable retainer plate  47  is pressed by the thread  46 . As a result, a force in the direction from the movable retainer plate  47  toward the fixed retainer plate  49  against the resilience of the spring  48  generates, and allows the ring  44  to be deformed into an elliptical shape. The thread  46  is screwed until the minor axis of the deformed rings  44  corresponds to the diameter of the small-diameter blood vessel. Then, an incision is made in a longitudinal direction from the end surface of the small-diameter blood vessel, the small-diameter blood vessel is elliptically opened, and the vascular wall is extended outward 90 degrees and impaled on the pins (refer to  FIGS. 3C to 3E ). 
     The ring  44  through which the large-diameter blood vessel is inserted is pressed by screwing the thread  46  to the same degree as above, and thereby the two rings are deformed into the same elliptical shape. In this example, in order to equalize the deformation amounts of the two rings, it is recommended that scale marks be provided on the outer frame  45  so that the amount of pushed-in of the thread (or the amount of movement of the movable retainer plate  47 ) could be checked. 
     The right and left cartridge components  41   a  and  41   b  are joined to allow the pins provided on the ring in one component to stick into the ring in the other component. Thus, the vascular anastomosis is completed (refer to  FIG. 3F ). After that, the thread  46  is pulled back outward so that the resilience of the spring  48  releases the movable retainer plate  47  from the pressed state and returns it to its original position. Further, as described in paragraph [0018], turning the rotary knob  24  shown in  FIG. 4  allows the support bar  25  to extend so that the protrusion  25   a  advances into the guide groove  43   a  provided on the ring holder  43  shown in  FIG. 7A  and pushes the rings  44  so that the rings  44  are released from the ring holder  43 . 
     Example 3 
     Here, the means for moving the movable retainer plate in Example 1 is replaced by bevel gears. 
     As described above, the cartridge at the tip of the vascular anastomosis device is housed in a cap, which is to be removed in the same manner as above. 
     As shown in  FIG. 8A , the cartridge comprises a pair of right and left components  50   a  and  50   b . The components  50   a  and  50   b  are held around the shaft with use of a spring  51 , and therefore, when the cap is removed, the spring force opens the cartridge. 
     The shaft as the rotation center of the cartridge is, as shown in  FIG. 8B , provided with a bevel gear  52 . From the tip of the rotatable driver  54 , which passes through the bar  53  (refer to  FIG. 8A ) held by the cylinder  23  (refer to  FIG. 4 ), an operation shaft  55  for the bevel gear  52  is protruded. In the cartridge component  50   a , another bevel gear  56 , which meshes with the bevel gear  52 , is provided. A rod  57  is protruded from the bevel gear  56 , and the rod  57  is provided with a threaded portion  58 . The cartridge component  50   a  comprises a movable retainer plate  59 , which comprises a threaded portion capable of meshing with the threaded portion  58  of the rod  57 . The rod  57  is in contact with the outer frame  60 , and the movement of the rod  57  to the right is prevented by the outer frame  60 . The outer frame  60  and a fixed retainer plate designated by  61  have stoppers  62  for preventing the movable retainer plate  59  from rotating. 
     When the operation shaft  55  at the end of the rotatable driver  54  is operated to rotate the bevel gear  52 , the bevel gear  56  meshing with the bevel gear  52  rotates and tries to send the rod  57  to the right, but the frame  60  prevents the movement. The counteraction forcibly sends the movable retainer plate  59  meshing with the threaded portion  58  of the rod  57  to the left. Since the threaded portion  58  of the rod  57  protruded from the bevel gear  56  meshes with the movable retainer plate  59 , rotation of the bevel gear  56  could horizontally rotate the movable retainer plate  59 . The stoppers  62 , however, prevent the horizontal rotation. Thus, the counteraction resulting from the prevention of the movement of the rod  57  to the right, that is, the movement of the movable retainer plate  59  to the left exerts a force on the ring  64  held by the ring holder  63  in the cartridge component  50   a  in the direction toward the fixed retainer plate  61 . The rod  57  is provided with the guide member  65 . There is no intention to provide detailed description, but the other cartridge component  50   b  has the same configuration, that is, comprises the ring holder  63 , the ring with pins  64 , the bevel gear  56 , the rod  57 , the movable retainer plate  59 , the outer frame  60 , the fixed retainer plate  61 , stoppers  62 , and the guide member  65 . In this example, the right and left movable retainer plates can move simultaneously and by the same amount. 
     The diameter of the rings  64  fits the large-diameter blood vessel. The large-diameter blood vessel is inserted through either of the right and left rings  64  and the vascular wall is impaled on the pins of the ring, as shown in  FIG. 3B . 
     After the small-diameter blood vessel is inserted through the other ring  64 , the operation shaft  55  at the end of the rotatable driver  54  is operated to rotate the bevel gear  52 . The bevel gear  56  meshing with the bevel gear  52  rotates and tries to send the rod  57  to the right, but the frame  60  prevents the movement. As the counteraction, the movement of the movable retainer plate  59  meshing with the threaded portion  58  of the rod  57  to the left exerts a force on the ring  64  held by the ring holder  63  in the cartridge component  50   a  in the direction toward the fixed retainer plate  61 . Consequently, the ring  64  is deformed into an elliptical shape. The operation shaft  55  is operated until the minor axis of the deformed rings  64  corresponds to the diameter of the small-diameter blood vessel. Since the deformation of the rings  64  by the operation of the operation shaft  55  occurs in the same manner in both the right and left cartridge components, the two rings  64  are deformed into the same elliptical shape. Then, an incision is made in a longitudinal direction from the end surface of the small-diameter blood vessel, the small-diameter blood vessel is elliptically opened, and the vascular wall is extended outward 90 degrees and impaled on the pins (refer to  FIGS. 3C  to  3 E). 
     The right and left cartridge components  50   a  and  50   b  are joined to allow the pins provided on the ring in one component to stick into the ring in the other component. Thus, the vascular anastomosis is completed (refer to  FIG. 3F ). After that, the operation shaft  55  is operated so that the bevel gear  52  rotates in the opposite direction to move the movable retainer plate  59  to the right. This movement releases the movable retainer plate  59  from the pressed state and returns it to its original position. Further, as described in paragraph [0018], turning the rotary knob  24  shown in  FIG. 4  allows the support bar  25  to extend so that the protrusion  25   a  advances into the guide groove  63   a  provided on the ring holder  63  shown in  FIG. 8A  and pushes the rings  64  so that the rings  64  are released from the ring holder  63 . 
     Example 4 
     In Example 4, in order to reduce the friction at the contact site between the rod  57  and the outer frame  60  in Example 3, a ball bearing  66  is attached to the contact site between the rod  57  and the outer frame  60 , as shown in  FIG. 9B . Needless to say, other means can also be employed as long as the friction at the contact site can be reduced. 
     Shape of Pins 
     In the cases where the rings with pins are made of a flexible material, the pin  67  having a conventional shape as shown in  FIG. 10A  and being made of a certain type of material has the risk of being pulled out after stuck into the other ring. In such a case, it is preferred to adopt the pin  68  shown in  FIG. 10B  or the pin  69  shown in  FIG. 10C  each having a harpoon-like shape, that is, having a barb. The head portions  68   a  and  69   a  of the pins  68  and  69  are straight, but they may be curved. In the pins  68  and  69 , the head diameter D must be larger than the shank diameter d, and the ratio of D to d is preferably about 1.5 or more. 
     Other Ring Features 
     In a preferable example, the pins and the inner portion of the ring are made of a hard material (for example, polyethylene), and the outer portion and other portions of the ring are made of a flexible material (see, for example, paragraph [0017]). In a recommendable example, as shown in  FIG. 11B , the head portions and the base portions of the pins  70  and the inner portion  72  (into which the pins of the other ring are to be inserted) of the ring  71  are made of a hard material, such as polyethylene, and the outer portion  73  and other portions of the ring  71  are made of a flexible material. Such a structure enables the head portions of the pin  70  made of a hard material to easily stick through the outer portion  73  made of a flexible material and to be securely caught in the inner portion  72  made of a hard material. In this way, the head portions of the pins on one of the rings facing with each other are securely caught in the inner portion of the other ring, and thereby the two rings are securely joined.  FIG. 11A  is a plan view of a ring with pins having a structure described above. 
     Further, for the prevention of slippage or falling of the ring during deformation, the outer side surface of the ring may be processed to have one or more appropriate flat surfaces. 
     INDUSTRIAL APPLICABILITY 
     The present invention is useful as a device for connecting and conglutinating two blood vessels with different diameters. 
     REFERENCE SIGNS LIST 
     
         
           1  Small-diameter blood vessel 
           2  Incision 
           3  Large-diameter blood vessel 
           4  Blood vessel 
           4   a  End portion of blood vessel 
           5  Truly circular ring 
           6  Vascular wall 
           7  Pin 
           7  Guide slit 
           8  Forceps 
           9   a  Tweezers 
           10  Anastomosis device 
           10   a  Guide plate 
           10   b  Guide groove 
           11   a , 11   b  Ring with pins 
           12  Large-diameter blood vessel 
           13  Vascular wall 
           14  Pin 
           15  Small-diameter blood vessel 
           16  Incision 
           17  Vascular wall 
           18  Pin 
           21  Ring with pins 
           22  Ring holder 
           22   a  Guide groove 
           23  Cylinder 
           24  Rotary knob 
           25  Support bar 
           25   a  Protrusion 
           25   b  Guide slit 
           26  Cap 
           27  Slot 
           28   a , 28   b  Cartridge component 
           29  Spring 
           30  Ring holder 
           30   a  Guide groove 
           31  Ring with pins 
           32  Outer frame 
           33  Movable retainer plate 
           34  Spring 
           35  Fixed retainer plate 
           36  Tapered threaded portion 
           37  Bar 
           38  Tapered threaded portion 
           39  Driver 
           40  Protrusion 
           41   a , 41   b  Cartridge component 
           42  Spring 
           43  Ring holder 
           43   a  Guide groove 
           44  Ring with pins 
           45  Outer frame 
           46  Thread 
           47  Movable retainer plate 
           48  Spring 
           49  Fixed retainer plate 
           50   a , 50   b  Cartridge component 
           51  Spring 
           52  Bevel gear 
           53  Bar 
           54  Driver 
           55  Operation shaft 
           56  Bevel gear 
           57  Rod 
           58  Threaded portion 
           59  Movable retainer plate 
           60  Outer frame 
           61  Fixed retainer plate 
           62  Stopper 
           63  Ring holder 
           63   a  Guide groove 
           64  Ring with pins 
           65  Guide member 
           66  Ball bearing 
           67 , 68 , 69 , 70  Pin 
           71  Ring 
           72  Inner portion 
           73  Outer portion 
           74  Flat surface