Abstract:
The stent graft system in accordance with the present invention has a trunk, a left subclavian tube, a left common carotid tube and a brachiocephalic tube. The trunk is tubular and expandable and has a descending end, an ascending end, a left subclavian mount, a left common carotid mount and a brachiocephalic mount, for receiving the aforementioned branch tubes that are elastic and self-expandable for respectively connecting the left subclavian artery, the left common carotid artery and the brachiocephalic artery to the trunk. With the above-described structure, the present invention allows fast determination of a suitable trunk and branch tubes for a patient and allows a medical institute to prepare compatible branch tubes and trunks for a composite stent graft system instead of numerous stent grafts of various combinations of differently sized tubular bodies and branches, wherein the former requires significantly less warehousing cost than the latter.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a stent graft system, especially to a composite branched stent graft system. 
         [0003]    2. Description of the Prior Art 
         [0004]    With reference to  FIG. 18 , a first conventional stent graft or prosthesis for open aortic arch surgery is used to support inner wall thereof as a treatment for aortic dissection or aortic arch aneurysm and comprises a tubular trunk  91 , a left subclavian arterial branch  911 , a left common carotid arterial branch  912  and a brachiocephalic arterial branch  913 . The tubular trunk  91  is made of self-expandable elastic material with expandable stents and comprises two ends  914 ,  915  for connecting to portions of the aortic arch. The two ends  914 ,  915  of the tubular trunk  91 , when mounted in the aortic arch, self-expand and thus attach themselves to the inner walls of the portions of aortic arch. The portion of the vicinity of the end  915  also comprises the expandable stents so as to mount the trunk  91  in the ascending aorta by the expanding stents. However, the tightening made possible by the expanding stents is observed to be insufficient to endure the pressure of the blood steam from ascending aorta and fails to sustain the trunk  91 . Furthermore, the expandable stents are embedded in or attached to the portions of the vicinities of the ends  914 ,  915  for mounting the trunk  91  in the aorta, while the rest portion of the trunk  91  are free from stents. Not being wholly embedded with reinforcing stents, the trunk  91  of the first conventional stent graft or prosthesis fails to keep the shapes of its original curves and can be forced straight when passing the blood streams. 
         [0005]    The left subclavian arterial branch  911 , the left common carotid arterial branch  912  and the brachiocephalic arterial branch  913 , made of the same self-expandable elastic material with expandable stents, are irremovably originated from and communicated with the tubular trunk  91 , and are respectively connected to and communicate with the left subclavian artery, the left common carotid artery and the brachiocephalic artery (innominate artery) by means of self-expansion therein. 
         [0006]    With reference to  FIG. 19 , a second conventional stent graft is similar to the foregoing stent graft, except that the self-expandable elastic tubular trunk  92  is made of longitudinally interleaved mesh and spring materials. The left subclavian arterial branch  921 , the left common carotid arterial branch  922  and the brachiocephalic arterial branch  923  of the second conventional stent graft are irremovably originated from a spring-material portion of the tubular trunk  92 . The second conventional stent graft attaches itself to the inner walls of the aortic arch and the branches by means of self-expansion. 
         [0007]    With further reference to  FIGS. 18 and 19 , the structure of each of the aforementioned conventional stent grafts provides a tubular trunk  91 ,  92  and irremovable branches  911 - 913 ,  921 - 923 . There are chances that even though the tubular trunk  91 ,  92  is suitable for the aortic arch of the patient, all or one of the branches  911 - 913 ,  921 - 923  may be ill fitting for the left subclavian artery, the left common carotid artery and/or the brachiocephalic artery. 
         [0008]    However, the diameters of aortae treated in a medical institution vary, so do the diameters of the left subclavian artery, the left common carotid artery and the brachiocephalic artery. A conventional stent graft whose trunk and all branches respectively compatible to the aorta and arteries being treated is indispensable in a surgery for aortic dissection or aortic arch aneurysm. This structural nature of the conventional stent grafts costs medical institutions a burden of preparing readily available stent grafts that come with various combinations of different sized tubular trunks  91 ,  92  and irremovable branches  911 - 913 ,  921 - 923 , so to satisfy the surgical need for engaging aortae and arteries of various diameters. 
         [0009]    One possible solution to the above-described shortcoming due to warehousing a large stock of various sized stent grafts is applying custom-made stent grafts. One apparent problem of the solution is its unacceptable expensiveness. In a clinical aspect of the custom-made stent grafts a more significant problem arises: custom-made stent grafts usually fail to provide clinically realistic readiness, especially in an emergent surgery. 
         [0010]    Said structural nature of conventional stent grafts also costs the surgeon considerable time for selecting a stent graft with specifically suitable tubular trunks  91 ,  92  and suitable branches  911 - 913 ,  921 - 923 , prior to or during an emergent surgery, such as acute aortic dissection or ruptured aortic aneurysm, in which the customized branched stent graft cannot be available timely. 
         [0011]    To overcome the shortcomings, the present invention provides a stent graft system to mitigate or obviate the aforementioned problems. 
       SUMMARY OF THE INVENTION 
       [0012]    The main objective of the invention is to provide a stent graft system. 
         [0013]    The stent graft system in accordance with the present invention has a trunk, a left subclavian tube, a left common carotid tube and a brachiocephalic tube. 
         [0014]    The trunk is tubular and expandable, preferably balloon-expandable or self-expandable, and has a descending end, an ascending end, a left subclavian mount, a left common carotid mount and a brachiocephalic mount. The mounts are for receiving the aforementioned branch tubes, i.e., the left subclavian tube, the left common carotid tube and the brachiocephalic tube. The branch tubes are made of various blood-impermeable materials, especially polyesteror polytetrafluoroethylene, where expandable, preferably self-expandable or balloon-expandable, stents are mounted on their inner or outer surfaces. The stents are also embedded in a portion of the branch tube for mounting in the trunk. Said expandable stents may be made of Nitinol, stainless steel, Co—Cr alloy, or other clinically acceptable material enabling the functionality of the stents. The branch tubes are used for respectively connecting the left subclavian artery, the left common carotid artery and the brachiocephalic artery to the trunk. 
         [0015]    With the above-described structure, the present invention allows a surgeon to separately select a suitable trunk, a left subclavian tube, a left common carotid tube and a brachiocephalic tube in the aortic arch surgery, which takes far less time than selecting a complete stent graft that coincidentally fits the aortic arch as well as the arteries of the patient. Furthermore, the structure of the stent graft system allows a medical institute to prepare compatible branch tubes and trunks for a composite stent graft system instead of numerous stent grafts of various combinations of differently sized tubular bodies and branches, wherein the former requires significantly less warehousing cost than the latter. 
         [0016]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a first embodiment of the trunk of the stent graft system in accordance with the present invention; 
           [0018]      FIG. 2  is a perspective view of a second embodiment of the trunk of the stent graft system in accordance with the present invention; 
           [0019]      FIG. 3  is a perspective view of a modified second embodiment of the trunk of the stent graft system in accordance with the present invention; 
           [0020]      FIG. 4  is a perspective view of a third embodiment of the trunk of the stent graft system in accordance with the present invention; 
           [0021]      FIG. 5  is a side view of a first embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0022]      FIG. 6  is a side view of a second embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0023]      FIG. 7  is a side view of a third embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0024]      FIG. 8  is a side view of a forth embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0025]      FIG. 9  is a side view of a fifth embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0026]      FIG. 10  is a side view of a sixth embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0027]      FIG. 11  is a side view of a seventh embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0028]      FIG. 12  is a side view of an eighth embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0029]      FIG. 13  is a side view of a ninth embodiment of a branch tube for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention; 
           [0030]      FIG. 14  is an exploded operational perspective view of a second example of the stent graft system in accordance with the present invention; 
           [0031]      FIG. 15  is an exploded operational perspective view of a first example of the stent graft system in accordance with the present invention; 
           [0032]      FIG. 16  is an operational perspective view of a trunk in  FIG. 1  connected to the aorta with a fastening belt; 
           [0033]      FIG. 17  is an operational perspective view of a trunk in  FIG. 1  connected to the aorta with another fastening belt; 
           [0034]      FIG. 18  is a perspective view of a conventional stent graft in accordance with the prior art; and 
           [0035]      FIG. 19  is a side view of another conventional stent graft in accordance with the prior art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    With reference to  FIGS. 1 ,  5 ,  7 ,  8  and  15 , a first example of the stent graft system in accordance with the present invention has a trunk  10 , a left subclavian tube  41 , a left common carotid tube  43  and a brachiocephalic tube  46 . 
         [0037]    The trunk  10  is tubular and expandable, preferably self-expandable or balloon-expandable. The trunk  10  comprises expandable stents embedded therein or mounted thereon, preferably made of meshes or springs or a combination thereof, wherein the material of the stents may be selected from various clinically acceptable materials, especially Nithnol, stainless steel or Co—Cr alloy. The trunk  10  comprises a descending end  15 , an ascending end  16 , a left subclavian mount  11 , a left common carotid mount  12  and a brachiocephalic mount  13 . The trunk  10  is used with its self-expanding or balloon-expandable feature to support the inner wall of the aorta as a treatment for aortic dissection or aortic arch aneurysm. The ascending and descending ends  16 ,  15  are respectively orientated to the ascending aorta and descending aorta within the aortic arch so to receive the blood flow from the ascending end  16  and distribute the same to the descending aorta through the descending end  15 , to the left subclavian artery (S) through the left subclavian mount  11 , to the left common carotid artery (L) through the left common carotid mount  12  and to the brachiocephalic artery (B) through the brachiocephalic mount  13 . 
         [0038]    The left subclavian mount  11 , the left common carotid mount  12  and the brachiocephalic mount  13  have respectively predefined diameter and are solid for receiving the left subclavian tube  41 , the left common carotid tube  43  and the brachiocephalic tube  46 . 
         [0039]    In the present example, the trunk  10  further comprises a control duct  14  originated from and communicated with the trunk  10 , allowing external access to the trunk  10 , the left subclavian tube  41 , the left common carotid tube  43  and the brachiocephalic tube  46  and switching the same into expanded status. The self-expandable branch tubes  41 ,  43 ,  46  respectively inserted in the mounts  11 - 13  firmly attach themselves therein when switched into expanded status. The control duct  14  is also used as an inlet for inducing blood to initiate a cardio-pulmonary bypass. 
         [0040]    With further reference to  FIGS. 5-12 , branch tubes  41 ,  42 ,  43 ,  46 ,  47 ,  48  of various structures are available options for forming a functional stent graft with the trunk  10  or with other embodiments of the trunk  20 ,  30  as shown in  FIGS. 2 and 4 . The aforementioned first example, though using specific branch tubes  41 ,  42 ,  43  with the trunk  10 , is for describing one of various feasible functioning embodiments of the stent graft system in accordance with the present invention, instead of for limiting the scope thereof in any aspect. 
         [0041]    With reference to  FIG. 2 , the second embodiment of the trunk  20  is structurally and functionally similar to the first embodiment and also comprises a descending end  25 , an ascending end  26 , a left subclavian mount  21 , a left common carotid mount  22 , a brachiocephalic mount  23  and a control duct  24 . The trunk  20  comprises an outer surface and multiple tabs  27 . The tabs  27  are attached to the outer surface between the left subclavian mount and the descending end of the trunk  20  for suturing the trunk  20  to the aortic arch, so to provide firm combination of the trunk  20  to the aortic arch. The trunk  20  may comprise multiple rings  28  or a combination of rings and tabs  27 . The rings  28 , through which seaming materials and apparatus are allowed to pass, are attached to the outer surface of the trunk  20  and function similarly as the tabs  27 . Both the tabs  27  and the rings  28  help to prevent slippage of the trunk  20  from the aortic arch. 
         [0042]    With reference to  FIGS. 4 and 14 , the third embodiment of the trunk  30  is structurally and functionally similar to the first embodiment and also comprises a descending end  35 , an ascending end  36 , a left subclavian mount  31 , a left common carotid mount  32 , a brachiocephalic mount  33  and a control duct  34 . The brachiocephalic mount  33  extends within the trunk  30  and comprises an inner end  331 . The inner end  331  points to the ascending end  36  of the trunk  30  in order to reinforce the junction portion between the trunk  30  and the brachiocephalic tube  41  so to better endure the pressure brought by the strong blood flow received therein through the ascending end  36 . 
         [0043]    With reference to  FIG. 5 , a first embodiment of a branch tube  41  for use as a left subclavian tube, a left common carotid tube or a brachiocephalic tube of the stent graft system in accordance with the present invention is expandable, preferably self-expandable or balloon-expandable made from a clinically blood-impermeable material, preferably polyester or polytetrafluoroethylene, where expandable stents are mounted on inner or outer surfaces of the branch tube  41 . The expandable stents may be made of meshes, springs or a combination thereof, and comprises a proximal end and a distal end. Preferably, the material of the stents may be Nitinol, stainless steel, Co—Cr alloy, or other clinically acceptable material. With reference to  FIGS. 1-4 ,  14  and  15 , the proximal end of the branch tube  41  is for mounting the left subclavian mount  11 ,  21 ,  31 , the left common carotid mount  12 ,  22 ,  32  or the brachiocephalic mount  13 ,  23 ,  33 . The distal end is for connecting to the left subclavian artery, the left common carotid artery or the brachiocephalic artery. 
         [0044]    With reference to  FIG. 15 , when used as a left subclavian tube for instance, after inserted in the left subclavian mount  11  of the trunk  10  and in the left subclavian artery, the branch tube  41  is maneuvered to expand, especially by means of external access through the control duct  14 , so to function as a subclavian tube. The expanded tube  41  then firmly attaches itself to the inner walls of the left subclavian artery and the left subclavian mount  11 , in order to pass blood flow from the trunk  10  to the left subclavian artery. 
         [0045]    With reference to  FIG. 16 , an additional fastener may be employed to further secure the connection of the descending aorta (DA) to the trunk  10  at the descending end  15 . One example of said additional fastener is a fastening belt  51  with attached ends  511 . With reference to  FIG. 17 , another example of said additional fastener is a fastening belt  52  whose ends are pinched with a pincher  521 . 
         [0046]    With reference to  FIG. 6 , a second embodiment of a branch tube  42 , which is structurally and functionally similar to the first embodiment, comprises an outer surface and multiple barbs  421 . The barbs  421  are circumferentially attached to the outer surface around the distal end of the branch tube  42 . When attached to the inner wall of an artery, the barbs  421  further secure the connection of the branch tube  42  and the artery, wherein the artery may be the left subclavian artery, the left common carotid artery or the brachiocephalic artery. With reference to  FIG. 10 , when the branch tube  42  is used as a left subclavian tube, the barbs  421  hook the inner surface of the subclavian artery to prevent detachment thereof. 
         [0047]    With reference to  FIG. 7 , a third embodiment of a branch tube  43 , which is structurally and functionally similar to the first embodiment, comprises an outer surface and multiple tabs  431 . The tabs  431  are attached to the outer surface between the distal end and the proximal end of the left subclavian tube. When the branch tube  43  is inserted in an artery, the surgeon may suture the tabs with the artery to provide secured connection between the branch tube  43  and the artery. With reference to  FIGS. 14 and 15 , when the branch tube  43  is used as a left common carotid tube, attachment of the tabs  431  to the left common carotid artery by use of sutures is preferred. With further reference to  FIG. 4 , the branch tube  43  is also suitable for mounting in the left subclavian mount  31 , the left common carotid mount  32  or the brachiocephalic mount  33  of the trunk  30 . 
         [0048]    With reference to  FIG. 8 , a forth embodiment of a branch tube  44  similar to the aforementioned third embodiment comprises an outer surface and multiple rings  441 . The rings  441 , attached to the outer surface of the branch tube  44  in a similar manner as the tabs  431  to the branch tube  43  in  FIG. 7 , allow seaming materials to pass through them, so to provide convenience in surgery. 
         [0049]    With further reference to  FIGS. 1-4  and  6 , a similar embodiment to the foregoing second embodiment of the branch tube  42  further comprises a reinforce ring formed on the outer surface around the proximal end of the branch tube  42 . The reinforced ring is elastic and capable of being deformed and compressed when mounted in a mount  11 - 13 ,  21 - 23 ,  31 - 33  of a trunk  10 ,  20 ,  30 . When the instant embodiment is deployed in the mount  11 - 13 ,  21 - 23 ,  31 - 33  and one of the three supra-aortic arteries, the ring is fully expanded and can be engaged on the margin of mount. 
         [0050]    With further reference to  FIGS. 1-4 ,  5  and  9 , the present invention also provides a fifth embodiment of a branch tube  45  similar to the aforementioned embodiment of the branch tube  41 , wherein no barbs as mentioned in the second embodiment of the branch tube  42 , however equipped with the above-described reinforced ring  451  formed on the outer surface around the proximal end. 
         [0051]    With reference to  FIG. 10 , a sixth embodiment of a branch tube  46 , which is structurally and functionally similar to the first embodiment, comprises a tubular wall and at least one notch  462 . Each notch  462  is indented from the proximal end allowing the proximal end of the branch tube  46  to form an efficiently receiving opening. With reference to  FIG. 15 , the branch tube  46 , suitable for using as a left subclavian arterial tube or a left common carotid arterial tube mounted in a corresponding mount, is also capable of being deployed as a brachiocephalic tube that mounted in the brachiocephalic mount  13 , so that the at least one notches  462  forms a stable and secure proximal fixation of the branch tube  46  in the trunk  10 . 
         [0052]    With reference to  FIGS. 11 and 12 , the seventh and eighth embodiments of branch tubes  47 ,  48 , both having at least one notch  472 ,  482 , and respectively multiple barbs  471  and multiple tabs  481 , are structurally and functionally similar to the sixth embodiment. The multiple barbs  471  have similar structure and arrangement as the barbs  421  of the second embodiment. The multiple tabs  481  have similar structure and arrangement as the tabs  431  of the third embodiment. 
         [0053]    With reference to  FIG. 13 , a ninth embodiment of a branch tube  49  similar to the aforementioned eighth embodiment comprises at least one notch  492 , an outer surface and multiple rings  491 . The rings  491 , attached to the outer surface of the branch tube  49  in a similar manner as the tabs  481  to the branch tube  48  in  FIG. 12 , allow seaming materials to pass through them, so to provide convenience in surgery. 
         [0054]    With further reference to  FIGS. 1-13 , each of the embodiments of the branch tubes described above, including branch tubes  41 - 49 , are capable of being mounted in any of the mounts  11 - 13 ,  21 - 23 ,  31 - 33  formed on a trunk  10 ,  20 ,  30  of the stent graft system in accordance with the present invention. A surgeon may select a suitable trunk  10 ,  20 ,  30  for a patient and determine suitable branch tubes according to the diameters and conditions of the arteries thereof in a reasonable short time. The stent graft system of the above-described structure provides a time saving means for surgeons to rapid select suitable branch tubes and trunks and is also economic and efficient for warehousing management of medical institutes.