Abstract:
A device for forming an anastomosis of blood vessels or ducts comprises: first and second engagement structures ( 7, 10; 35 ) for respectively engaging a first end portion ( 2 ) of a blood vessel ( 1 ) or of a prosthesis and a second end or side portion ( 4, 4 ′) of the blood vessel ( 1 ) or prosthesis; and a mechanism ( 14, 14 ′) for reciprocally connecting the first and second engagement structures. The first engagement structure ( 7, 10 ) comprise one or more piercing elements ( 6 ) adapted to only partially penetrate the side wall of the blood vessel ( 1 ) so as to avoid direct contact between the elements ( 6 ) and the blood inside the vessel or prosthesis.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a device and method for anastomosis.  
         [0002]     In surgery, the term “anastomosis” is used to mean a connection made surgically between two hollow structures.  
         [0003]     In particular, when the structures connected are the two ends of a blood vessel, a lymphatic vessel or other type of duct, the operation is called end-to-end anastomosis and its purpose is to restore flow to the vessel or duct.  
         [0004]     The surgical connection between an end portion of a blood vessel to a side portion of a vessel wall, on the other hand, is termed “end-to-side anastomosis”.  
         [0005]     This specification expressly refers to vascular anastomosis applied to the human body, without thereby restricting the scope of the invention.  
         [0006]     The earliest method of anastomosing two parts of a blood vessel or lymphatic vessel consists in suturing the free ends of the vessel with thread.  
         [0007]     This method, commonly known as suture anastomosis, has several disadvantages, the main one being that the suture produces a scar which, however small, prevents original flow from being perfectly restored to the vessel.  
         [0008]     In this connection, it should be stressed that blood vessels are made up of several layers. The first, innermost layer, called endothelium, is covered by a second, middle layer called tunica media. The tunica media is in turn covered by a third layer, known as tunica adventitia.  
         [0009]     It is therefore relatively easy for suturing to cause misalignment of some kind between the layers of one end of the vessel and the corresponding layers of the end of the other vessel. This is also a drawback in the case of lymphatic vessels, which have a similar layered structure.  
         [0010]     A second drawback is due to the fact that blood vessel suturing must be done by hand by a specialized surgeon because it is a complex operation that cannot be left to surgeons who are not highly skilled in this specific art.  
         [0011]     Another known method of anastomosing two parts of a blood or lymphatic vessel is to use mechanical clamping devices designed to turn the ends to be connected inside out and to then join the inside walls of the vessel ends to each other.  
         [0012]     This surgical technique (mechanical anastomosis by eversion), although simpler than suture anastomosis, is even less effective in restoring flow to the vessel.  
         [0013]     For example, in the specific case of blood vessels, only the intimal layers are in contact with each other.  
         [0014]     Besides this, mechanical anastomosis by eversion has other serious drawbacks which may be dangerous to the patients.  
         [0015]     One drawback is due to the fact that everting the vessel ends may cause the ends to break, especially in the case of vessels larger than 3 mm in diameter whose walls are stiffened by arteriosclerosis.  
         [0016]     Another complication, specific to blood vessels, is caused by the fact that the inside layers of the vessel ends, after being turned inside out and placed side by side, are no longer exposed to blood flow and therefore tend to atrophy, which in turn leads to narrowing of the blood vessel and reduction of the blood flow through it. The smaller the diameter of the vessel being operated on is, the more serious this problem is.  
         [0017]     In other mechanical anastomosis methods (such as the one described in U.S. Pat. No. 6,652,540) the two ends of the vessels to be joined are not placed in contact and, instead, metallic components are left in contact with the blood flowing through the vessel. This produces an extremely dangerous condition which exposes the anastomosis to risk of immediate occlusion caused by the formation of a blood clot.  
         [0018]     The prior patent application BO2000A000169, in the name of the same Applicant, describes an apparatus for end-to-end anastomosis in which the means for mutually connecting the vessel portions to be anastomosed enable the ends of the vessel to be held in place exactly so that the edges of the vessel match perfectly.  
         [0019]     This solution solves many of the above mentioned problems thanks to its simple construction and to the fact that, once implanted, it enables the vessel to be reconstructed completely.  
         [0020]     Although contamination of the blood due to contact with the connecting parts of the apparatus is less serious than in earlier solutions, the problem has not been totally solved, especially when the connecting parts are made of metal.  
         [0021]     Indeed, it has been found that contact between metal and blood tends to cause stenosis, that is to say, abnormal narrowing of the blood vessel, which may lead to total occlusion of the vessel in a period of 6 months to 1 year.  
         [0022]     Those in the art have proposed to overcome the problem by chemically coating the metals with anti-stenosis substances, that is to say, substances that inhibit occlusions.  
         [0023]     This solution has, however, produced serious problems because in many cases, the chemically coated metal parts in contact with the blood favor the formation of thrombi and the onset of acute thromboses that come sharply to a crisis, exposing patients to the risk of heart failure and, in some cases, leading to death.  
       SUMMARY OF THE INVENTION  
       [0024]     A first aim of the present invention is to provide a method and an apparatus for mechanical anastomosis that overcomes the problems caused by contact between the metal or artificial parts and the blood.  
         [0025]     Another aim of the invention is to propose an anastomosis device that permits flow in the blood vessel to be re-established more effectively than prior art devices.  
         [0026]     These aims are achieved by a device and method according to the main claims.  
         [0027]     A first advantage of the invention is that contact between the connecting parts and the blood vessel is limited to the vessel wall, leaving the inside surface free, and there is therefore no contact with the blood inside the vessel.  
         [0028]     Another advantage is that the layers making up the blood vessel are only partially broken which means that, after the operation, the vessel heals more quickly.  
         [0029]     Yet another advantage is that the device supports the vessel wall radially from the outside at its front edge so that it maintains the required size and is prevented from contracting.  
         [0030]     A yet further advantage is the absence of interference between the engagement means and the free front edge of the vessel, which, combined with the ability to keep the vessel at the required, measured size, permits an optimum connection between the different layers making up the anastomosed parts of the vessel.  
         [0031]     A yet further aim of the invention is to propose a simplified anastomosis apparatus whose use can be learned in a very short time and which permits the formation of anastomoses of constant quality.  
         [0032]     A still further aim of the invention is to propose an anastomosis apparatus that reduces the time required for the anastomosis operation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]     The invention will now be described with reference to the accompanying drawings which illustrate a preferred embodiment of it and in which:  
         [0034]      FIG. 1  is an exploded view of an embodiment of the device according to the present invention in an end-to-end application;  
         [0035]      FIG. 2  is a cross section of the apparatus of  FIG. 1  in a working configuration;  
         [0036]      FIG. 3  is a detail view from above showing an outer connecting cylinder of the apparatus of  FIGS. 1 and 2 ;  
         [0037]      FIGS. 4   a  and  4   b  are, respectively, a cross section similar to  FIG. 2  but showing a different embodiment of the connecting means, and a detail view from above of an outer connecting cylinder of the apparatus of  FIG. 4   a;    
         [0038]      FIGS. 5   a  and  5   b  illustrate an applicator for the device according to the invention, the applicator being shown, respectively, in the open configuration and in the closed configuration in which it applies the device to an anastomosed vessel;  
         [0039]      FIG. 6  is a cross section of a device according to the present invention in an end-to-side anastomosis application. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]     With reference to  FIG. 1 , the numerals  2  and  4  denote a first and a second end portion of a blood vessel wall to be connected by end-to-end anastomosis.  
         [0041]     In the embodiments described, the device according to the invention comprises: 
        at least one first engagement element  7  for grasping one of the end portions  2 ,  4  of the blood vessel; and     at least one second engagement element  10  designed to securely engage a first element  7  applied to a respective end portion  2 ,  4 .        
 
         [0044]     In the embodiment illustrated in FIGS.  1  to  4   a , relating to an end-to-end application, the device also comprises a second connecting element consisting of an outer cylinder  14  for reciprocally connecting two second engagement elements  10  applied to the end portions  2 ,  4  of the vessel.  
         [0045]     Looking in more detail, the first engagement element  7  consists of a substantially cylindrical body comprising an uninterrupted ring-shaped part  8  which has a plurality of longitudinal legs  6  protruding from the front of it, preferably equispaced and positioned in such a way as to form an annular protrusion or stop lip  9  on the front surface of the ring  8 .  
         [0046]     The second engagement element  10  consists of a cylindrical element whose outside diameter is equal to the uninterrupted ring-shaped portion  8  of the cylinder  7  and which preferably has an annular recess  13  made in its outside surface.  
         [0047]     Further, the inside diameter of the middle cylinder  10  is such that the latter can precisely slide over the inner cylinder  7  until it comes to a stop against the protrusion  9  and remains locked to the cylinder  7  with slight mechanical interference.  
         [0048]     Inside, the cylinder  10  has a tapered profile  28  that converges towards its front portion  26 , so that the inside diameter at the free edge of the front portion  26  substantially coincides with the inside diameter of the uninterrupted portion  8  of the inner cylinder  7 .  
         [0049]     The outer cylinder  14 , shown in more detail in  FIG. 3 , has an inside diameter that is equal to, or slightly larger than, the outside diameter of the middle cylinder  10 , and presents a substantially H-shaped cavity  29 , within which there protrude two flexible tabs  15 , which converge inwards slightly and are positioned in such a way that, when the outer cylinder is placed over the cylinder  10 , the tabs  15  are aligned with, and can snap into, the recess  13 .  
         [0050]     Described below with reference in particular to  FIG. 2  is the configuration of the device applied to two end portions  2 ,  4  in an end-to-end anastomosis.  
         [0051]     In the application configuration of the device, each of the end portions  2 ,  4  to be connected is inserted into a cylinder  7  with the legs  6  facing the free edge  25  of the vessel wall. To enable the inner cylinders  7  to grasp the end portions  2 ,  4  of the vessel wall  1 , the cylinders  7  are made to slide lengthwise in the middle cylinders  10  in such a way that the legs  6 , initially coaxial and parallel to the vessel wall, or slightly divergent, are made to bend inwards by contact with the tapered profile  28  so that they converge towards the inside of each cylinder  7 , pressing against the upper surface  24  of the vessel wall  1  and partially penetrating the latter close to the free edge  25 .  
         [0052]     Advantageously, the depth to which the legs  6  penetrate the vessel wall  1  is determined by the special shape of the legs  6  and of the tapered profile  28  of the cylinder  10 , which are so designed that the legs do not go right through the vessel wall, thus avoiding contact between the legs  6  and the blood inside the vessel.  
         [0053]     Once the cylinders  7  have been inserted into the cylinders  10 , both the end portions  2 ,  4  are securely fastened by the respective inner cylinder  7  whose legs  6  grasp the vessel walls  1  and which is in turn stably coupled to the middle cylinder  10  by a mechanical interference fit, although it will be understood that the stable coupling between the inner cylinder  7  and the middle cylinder  10  might also be accomplished by bayonet coupling, snap fitting, screw fastening or other suitable fastening means.  
         [0054]     At this point, to complete the connection between the portions  2  and  4 , it is sufficient to insert the middle cylinders  10  into the two ends of the outer cylinder  14  until the respective tabs  13  snap into the recesses  15  in the cylinders  10 .  
         [0055]     Under these conditions; illustrated in cross section in  FIG. 2 , the outer cylinder  14  holds together the middle cylinders  10  which are in turn locked to the inner cylinders  7  grasping the walls  1  of the end portions  2  and  4 .  
         [0056]     Further, the anastomosed blood vessel has no foreign objects protruding on the inside of it to interrupt the continuity of its lumen, with the advantage of not contaminating the blood or reducing normal blood flow.  
         [0057]     Moreover, the legs  6  keep the vessel wall  1  at a precisely measured diameter, which is the same as that of the two end portions  2  and  4  so that the free edges  25  of both coincide exactly and the different layers of the anastomosed vessel tissue are properly healed.  
         [0058]     With reference to  FIGS. 4   a  and  4   b , the connection between the components of the device may also be made, instead of or in combination with the above, by providing the outer surface of the uninterrupted ring-shaped portion  8  of the inner cylinder  7  with an annular recess  13 ′ similar to the recess  13 , combined with tabs  15 ′ (similar to the tabs  15  described above) on the cylinder  14  made at that recess.  
         [0059]     In this case, all the components are “packed” in the outer cylinder  14 , thus guaranteeing the stability of the connection even in the absence of a stable coupling between the inner cylinder  7  and the middle cylinder  10 .  
         [0060]     Described below with reference to  FIGS. 5   a ,  5   b  is an applicator apparatus for implanting a device according to the invention to the end portions  2 ,  4  of a blood vessel.  
         [0061]     The applicator comprises a rod  30  which is equipped at one end with a nosepiece  43  of measured diameter and which, by means of a threaded coupling  31 , can be screwed into a hollow piston  32  against the action of a spring  39 .  
         [0062]     The piston  32  is in turn slidable, by means of a second screw coupling  33 , inside a hollow body  34 , whose top end has a number of flexible tabs  35  normally spread outwards and extending frontally past the nosepiece  43 .  
         [0063]     A slider  36  can also move on the outside of the hollow body  34 , constrained by a tooth  37  that slides in a longitudinal groove  38  made in the body  34 .  
         [0064]     The slider  36  can adopt a first position in which the tabs are spread apart ( FIG. 5   a ) and a second end position ( FIG. 5   b ) in which the slider has moved towards the end of the body  34  and forced the tabs  35  to converge and close.  
         [0065]     To use the applicator, a cylinder  10  is inserted into it through the opening defined by the tabs  35  until the front portion  26  stops against the head  41  of the piston  32 .  
         [0066]     Next, a circular staple  7  is partially inserted into the cylinder  10  without forcing and the tabs  35  are closed and positioned at the back in such a way as to hold the ring portion  8  of the circular staple  7 .  
         [0067]     By operating the applicator, the surgeon inserts a vessel end portion  2  through the circular staple  7  and the cylinder  10  until the edge  25  of the vessel  2  is made to touch on the head  41  of the piston  32 .  
         [0068]     Preferably, the front portion  26  of the cylinder  10  also has a set of semicircular indentations  27  which, during use, ensure that the vessel end portion  2 ,  4  to which the device is applied is correctly positioned.  
         [0069]     Advantageously, the indentations  27  of the cylinder  10  ensure that the vessel wall has stopped against the piston  32 .  
         [0070]     By operating on the grip  40  of the rod  30 , it is now possible to advance the nosepiece  43  into the vessel  2  in such a way that the vessel remains precisely clamped between the nosepiece  43  itself and the inside surface at the front of the cylinder  10 .  
         [0071]     The nosepiece is preferably variable in diameter and consists, for example, of a helical wire winding extending in the direction of the rod  30 , where the two ends of the helix are fixed to respective elements that can turn relative to each other in such a way so as to move closer together/apart and thus vary the radial dimension of the winding.  
         [0072]     By twisting the grip  41  of the piston  32 , the surgeon can now advance the piston relative to the tab body so that the tabs and the piston come into contact and clamp the circular staple  7  within the cylinder  10 .  
         [0073]     As described above, when the legs  6  come into contact with the tapered inside surface  28  of the cylinder  10 , they are forced to converge and partially penetrate the vessel wall  2 .  
         [0074]     Once clamped by the piston  32 , the staple  7  is held by interference in the cylinder  10 , whilst the vessel wall  2  is retained frontally and radially by the legs  6 , with the edge  25  flush with or just protruding from the front  26  of the cylinder  10  and with an internal diameter or lumen defined by the size of the nosepiece  43  used.  
         [0075]     At this point, it is sufficient to twist the piston  32  in the opposite direction to retract the slider  36  to open the tabs  35  and release the applicator from the vessel wall.  
         [0076]     Once the device has been applied, the vessel end portions  2 ,  4  have a desired measured diameter thanks to the hold that the legs  6  have on the edge  25 . Also, the edge  25  of each of the two end portions remains whole, completely free from external elements, and the vessel protruding elements on the inside of it.  
         [0077]     It is evident that, under these conditions, optimum flow is re-established naturally in the blood vessel without external elements or interruptions leading to the above mentioned vessel healing difficulties and to the possible formation of stenosis due to the contact of extraneous elements with the blood.  
         [0078]     For reciprocally connecting the two ends  2 ,  4 , provided by the applicator of an engagement device, it is sufficient to apply an outer cylindrical element  14  as described above.  
         [0079]     Described below with reference to  FIG. 6  is a device according to the invention used for forming an end-to-side anastomosis.  
         [0080]     For convenience, where possible, parts corresponding to those described above have assigned to them the same reference numbers as those used above.  
         [0081]     In this case, the anastomosis device according to the invention is connected to an end portion  2  of a blood vessel in the same way described above and an applicator like the one already described.  
         [0082]     Unlike the above, the outer connecting element consists, in this case, of an outer cylindrical element  14 ′ forming part of a side connecting unit, generically labeled  35  in  FIG. 6 .  
         [0083]     As described above with reference to the connection between the tabs  15  and the recess  13 , the element  14 ′ also has elastically deformable tabs  15 ′ designed to snap into the recess  13  in the cylindrical element  10 , in order to prevent the end portion  2  from being moved away.  
         [0084]     For example, the means for engaging the unit  35  with the vessel wall (which do not in themselves form part of the invention and are therefore not described in detail) may comprise a side connecting element  16  joined stably, either removably or not, to the end connection  14 ′ and designed to be placed at least partially over a side portion  4 ′ of the vessel.  
         [0085]     In the schematic example illustrated in  FIG. 6 , the side element  16  has a central hole  20  which communicates with the element  14 ′ and whose position is such that it can be aligned, during use, with a cut  24  made in the vessel wall  4 ′ by a suitable circular scalpel according to a known method.  
         [0086]     The element  16  is equipped with means for fastening it to the portion  4 ′ and consisting for example of fasteners  17 , such as metal staples, with or without shape memory, adapted to engage with the wall  4 ′.  
         [0087]     The means for fastening the element  16  to the portion  4 ′ may be of a different type such as, for example, mechanical means (clamps) or glued means.  
         [0088]     As stated above, although the invention is especially advantageous for anastomosing blood vessels, the device and the applicator described above may also be used for prosthesis applications.  
         [0089]     This invention has been described with reference to preferred embodiments of it but it will be understood that it may be modified and adapted in several ways without thereby departing from the scope of the inventive concept.