Abstract:
A multiple-component expandable endoluminal system for treating a lesion at a bifurcation including a self expandable tubular root member having a side-looking engagement aperture, a self expandable tubular trunk member comprising a substantially blood impervious polymeric liner secured therealong; both having a radially compressed state adapted for percutaneous intraluminal delivery and a radially expanded state adapted for endoluminal support.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is continuation of U.S. application Ser. No. 12/529,936, filed Sep. 4, 2009, which is the US National Stage of International Patent Application PCT/IL2008/000287, filed Mar. 5, 2008, which published as WO 08/107,885, and which claims the benefit of U.S. Provisional Applications 60/892,885, filed Mar. 5, 2007, and 60/991,726, filed Dec. 2, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to endoluminal grafts, and particularly to bifurcated endoluminal grafts. 
       BACKGROUND OF THE INVENTION 
       [0003]    For a few decades, conventional treatment of abdominal aortic aneurysms (AAA) was limited either to a sit-and-wait strategy, or in cases with too high a risk for aneurysm rupture, a surgical operation using vascular grafts introduced in major open abdominal surgery. 
         [0004]    While long term clinical results of the surgical approach were favorable and the treated patients did not need frequent follow-ups, nevertheless the short-term morbidity, including complication rate, hospitalization time, out-of-work period and related expenses warranted continued search for a less invasive, but still definitive, solution of the problem. 
         [0005]    Numerous attempts have been made to introduce such definitive treatments to AAA that involve less morbidity, a shorter hospitalization period and lower related costs, and enable the patient to return to routine life sooner. These initiatives resulted in various endovascular stent-grafts that are commercially available or are being clinically and pre-clinically evaluated. A major advantage in these newer devices is that their implantation involves a significantly less invasive procedure, including creating an endovascular working channel—usually via an incision in the groin area—to the diseased abdominal aorta, through which a self expandable stent-graft is typically introduced. In most cases, a bifurcated device is employed, either in one piece, or in some cases, smaller caliber iliac-grafts are deployed subsequently after the main aortic devices have been well positioned. 
         [0006]    Nonetheless, the relatively new endovascular approach has its share of problems and limitations. Some of the major outstanding problems include:
       The implantation is complicated because most AAA stent grafts are implanted via two working channels, one in each side of the groin. The interventional radiologist typically has to introduce one main piece of the device via one working channel and an extension piece through the other side in a non trivial manner.   There is a prolonged implantation procedure caused by a difficulty to correctly position the stent-graft and the inability to correct its position once deployed, usually due to barbs that penetrate the aortic wall and anchor the graft thereto. This also involves relatively high doses of X-ray radiation, to which the patient and the staff are exposed during the prolonged endovascular procedure.   In earlier AAA stent grafts, device migration was a major issue, sometimes leading to obstruction of blood flow into the neighboring renal arteries or in other cases exposing the aneurysm to renewed blood penetration. Conventional AAA stent-grafts were typically prone to migration since they are essentially built along a single longitudinal axis and they may migrate along the same axis.   Endovascular leaks (in short—endoleaks) are another problem. Two types of endoleaks are defined: A type I endoleak is leakage of blood around the stent-graft and into the aneurismal sac, which may lead to rupturing the aneurysm. A Type II endoleak occurs when blood/plasma leaks through the graft wall and into the aneurismal space. Type II endoleaks have been mostly resolved by the introduction of finer-woven graft fabrics, performing pre-clotting procedures and/or incorporation of collagen or other procoagulation materials into the graft wall. Type I endoleaks are nonetheless more difficult to prevent and treat.   The device cost is very high. Current self-expandable AAA stent-grafts are usually bifurcated grafts, one piece or multi-piece devices. The connection with the graft fabric is typically achieved by hand stitching to a metallic, self-expandable frame. Hand labor related issues together with the critical QA/QC standards with which these devices have to comply make these devices quite expensive to manufacture.   There are the necessary follow-ups which are time consuming.       
 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention seeks to provide novel bifurcated endoluminal grafts that overcome the abovementioned problems of the prior art, as described more in detail hereinbelow. The present invention seeks to reduce the laborious and complicated multi-step medical procedures and related cost of the device. The present invention involves significantly fewer, simpler, quicker and more definitive medical steps. The present invention uses simpler device modules, which make the endovascular treatment of AAA quicker, safer for the patient and the treating staff, more reliable and cheaper. 
         [0014]    The present invention can reduce the number of vascular access sites from two femoral arteries in both sides of the groin to a single vascular access site. The present invention can reduce the risk of device migration in AAA stent grafts. 
         [0015]    There is provided in accordance with an embodiment of the invention a stent graft system including a first component  60  including a tubular structure having a support element  63  and a covering element  62  attached thereto, the first component  60  being positionable in first and second branches that bridge a main trunk of a subject and wherein the first and second elements have an opening  61  arranged to face the main trunk, and a second component  70  having a generally cylindrical form with a support element  72  and a covering element  71  attached thereto, the second component  70  configured to be at least partially disposed within the first component  60 , outwardly extending from the opening  61  in the first component  60 . 
         [0016]    One or both of the first and second components may be adapted for transluminal delivery for transport to a site within a body lumen by being radially compressed from a larger cross-section to a smaller cross-section. 
         [0017]    In accordance with an embodiment of the invention the covering element of the first component only partially covers the support element of the first component. 
         [0018]    In accordance with an embodiment of the invention the covering element of the second component only partially covers the support element of the second component. 
         [0019]    Further in accordance with an embodiment of the invention the first and second components are radially compressible from a larger cross-section to a smaller cross-section, and wherein the first and second components are adapted for transluminal delivery for transport to a site within a body lumen, and wherein the second component is adapted for transluminal delivery through the first component in its larger cross-section and to outwardly extend from the opening in the first component. For example, the first component in its larger cross-section may be dimensioned to intraluminally fit iliac arteries of a subject and the second component in its larger cross-section may be dimensioned to intraluminally fit an abdominal aorta of the subject. 
         [0020]    In accordance with an embodiment of the invention the second component includes a proximal segment and a distal segment, and wherein the covering element substantially spans the distal segment but does not generally span the proximal segment. The proximal segment may be dimensioned to be anchorably disposed within the first component. The proximal segment of the second component may be substantially disposed within the first component. The distal segment of the second component may outwardly extend from the opening in the first component. 
         [0021]    There is provided in accordance with an embodiment of the invention a method including implanting a stent graft system into a bifurcation in a body lumen, the bifurcation including a main trunk and first and second branches, wherein a first component of the system is disposed within the first and second branches bridging the main trunk and wherein the first and second elements have an opening aligned to face the main trunk, and implanting a second component in the main trunk such that at least a portion of the second component is located within the main trunk and at least a portion of the second component is located within the first component. 
         [0022]    There is provided in accordance with an embodiment of the invention a multiple-component expandable endoluminal system for treating a lesion at a bifurcation including a self expandable tubular root member having a side-looking engagement aperture, a self expandable tubular trunk member including a substantially blood impervious polymeric liner secured therealong, both having a radially compressed state adapted for percutaneous intraluminal delivery and a radially expanded state adapted for endoluminal support, wherein root member and the trunk member are individually deployable, and wherein the trunk member is substantially non compressible along its longitudinal axis, and wherein the circumference of the side-looking engagement aperture is capable of having a substantially identical shape as the circumference of the body portion of the trunk member in its radially relaxed state, and wherein the trunk member is adapted to be inserted intraluminally through either ends of root member when in its deployable state and thereafter extraluminally substantially exiting through its side-looking engagement aperture and perpendicular thereto, and wherein the distal end of trunk member is adapted to be anchorably deployable through the side-looking engagement aperture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
           [0024]      FIG. 1  is a simplified pictorial illustration of one possible insertion step in the deployment of an endoluminal graft in a non-limiting embodiment of the present invention; 
           [0025]      FIG. 2  is a simplified pictorial illustration of another deployment step of the endoluminal graft in a non-limiting embodiment of the present invention; 
           [0026]      FIG. 3  is a simplified pictorial illustration of a stent graft component of the endoluminal graft free of its catheter and positioned such that it has an open end located within each bifurcation branch and an aperture is facing the main trunk; 
           [0027]      FIG. 4  is a simplified pictorial illustration of another deployment step of the endoluminal graft in a non-limiting embodiment of the present invention; 
           [0028]      FIG. 5  is a simplified pictorial illustration of another deployment step of the endoluminal graft in a non-limiting embodiment of the present invention; 
           [0029]      FIG. 6  is a simplified pictorial illustration of the stent graft system in place in accordance with an embodiment of the present invention; 
           [0030]      FIGS. 7-12  are simplified pictorial illustrations of another preferred embodiment of the present invention, wherein a catheter is inserted in a fashion similar to the embodiments of  FIGS. 4-6 ; 
           [0031]      FIG. 13  is a simplified pictorial illustration of a non-limiting embodiment of an anchoring mechanism between first and second stent graft components; 
           [0032]      FIG. 14  is a simplified pictorial illustration of another non-limiting embodiment of an anchoring mechanism between stent graft components; 
           [0033]      FIG. 15A  is a simplified pictorial illustration of a non-limiting embodiment of a stent graft component with an aperture evident in the graft material; 
           [0034]      FIGS. 15B and 15C  are simplified pictorial illustrations of a non-limiting embodiment of stent graft component wherein the component includes sections with varying diameters; and 
           [0035]      FIGS. 16A and 16B  are simplified pictorial illustrations of the flow of blood through the joined stent graft components. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0036]    Reference is now made to  FIG. 1 , which illustrates one possible insertion step in the deployment of a component of an endoluminal graft in a non-limiting embodiment of the present invention. A catheter  100  is percutaneously inserted into a bifurcation  12  (e.g., one iliac artery) extending from a main trunk  10 , using conventional transluminal methods, such as with a guidewire  50 . The catheter  100  is bent or deflected at an angle so that it passes the main lumen and is then introduced into a second bifurcation  13  (e.g., the second iliac artery) extending from the main trunk  10 .  FIG. 1  shows two branch arteries (arterial ostia)  14  and  15  branching from main trunk  10 . There is an aneurysm  11  in the main trunk  10 . Catheter  100  includes two catheter portions  101  and  102 . Bifurcations  12  and  13  may also be referred to as arterial ostia  12  and  13 . 
         [0037]    Reference is now made to  FIG. 2 , which illustrates another deployment step of a component in a non-limiting embodiment of the present invention. Both the distal and proximal ends of the catheter portions  101  and  102 , respectively, are moved in opposite directions (e.g., by suitable manipulation of guide wires attached thereto, not shown) so that a stent graft component  60  which is in a compressed state within the catheter is gradually freed. An aperture  61  in the stent graft component  60  is positioned by the operator (e.g., by suitable manipulation of a guide wire attached thereto, not shown, and assisted by imaging such as fluoroscopy) such that it faces the main trunk  10 .  FIG. 3  illustrates the stent graft component  60  free of its catheter and positioned such that it has an open end located within each bifurcation  12  and  13  respectively, while aperture  61  is facing the main trunk  10 . 
         [0038]    Reference is now made to  FIG. 4 , which illustrates another deployment step of a component in a non-limiting embodiment of the present invention. A second catheter  200  is inserted through one open end of the first stent graft component  60  so that its distal end extend through the aperture  61  in the first stent graft component and is located within the main trunk  10 . 
         [0039]    Reference is now made to  FIG. 5 , which illustrates another deployment step of a component in a non-limiting embodiment of the present invention. A second stent graft component  70  is gradually freed from its restraining catheter. Catheter outer tube  202  is withdrawn so that the stent graft component  70  is gradually free to expand in a radial direction, such that the graft component&#39;s distal end engages the walls of the main trunk  10  below arterial ostia  12  and  13 , for example, the renal artery ostia. As the second stent graft component  70  is freed from the circumferential confines of the outer catheter tube  202 , its proximal end engages the first stent graft component  60 , thus anchoring the second stent graft component  70  to the first stent graft component  60 . 
         [0040]      FIG. 6  schematically illustrates the stent graft system in place, with the second stent graft component  70  having one end engaged radially against the wall of the main trunk  10  under arterial ostia  12  and  13 , while its proximal end is concentrically located within one end of the first stent graft component  60 . 
         [0041]      FIGS. 7 through 12  illustrate another preferred embodiment of the present invention, wherein a catheter  70  is inserted in a fashion similar to the one described in  FIGS. 4 ,  5  and  6 . Stent graft component  70  is freed from its catheter  200  by retracting outer catheter tube  202  so that its distal end is free within the main trunk lumen. The distal end of said second stent graft component  70  may or may not touch the lumen walls of the main trunk. The proximal end of the second stent is located concentrically within one section of the first stent graft component  60  so that it is anchored by the first stent graft component. A catheter  300  is inserted in a similar fashion through an open end of the first stent graft component  60 , and through the proximal end of the second stent graft component  70  located concentrically within the first stent graft component  60 . Catheter  300  is inserted such that its proximal end extends beyond the open distal end of the second stent graft component  70 . A third stent graft component  80  is released from the catheter so that its distal end radially engages the lumen walls of the main trunk  10 . As the third stent graft component  80  is further released, its proximal end engages the second stent graft component  70  in a radial fashion, forming an anchoring point between the second stent graft component  70  and the third stent graft component  80 . 
         [0042]      FIG. 12  shows elements of stent graft component  80  engaging the lumen walls of main trunk  10  such that support elements  82  engage the lumen wall above arterial ostia  12  and  13 . Graft covering  81  does not extend above the arterial ostia so as not to block blood flow into the ostia  14  and  15 . 
         [0043]      FIG. 13  schematically illustrates a non-limiting embodiment of the anchoring mechanism between the first stent graft component  60  and the second stent graft component  70 . In this embodiment, engagement arms  73  and  74  are located circumferentially on the second stent graft component  70  in at least two rows above and below aperture  61  in stent graft component  60 . The rows of engagement arms  73  and  74  are formed so as to grasp both sides of aperture  61  in stent graft component  60 . The two stent graft components are joined together as a result. 
         [0044]      FIG. 14  schematically illustrates another non-limiting embodiment of the anchoring mechanism between stent graft component  60  and stent graft component  70  whereby the proximal end of stent graft component  70  is concentrically located within at least a portion of stent graft component  60  with a section of the second stent graft component  70  extending through the aperture  61  and within a portion of stent graft component  60 . The graft covering  71  does not necessarily extend throughout the length of stent graft component  70 . 
         [0045]      FIG. 15A  schematically illustrates a non-limiting embodiment of stent graft component  60  wherein aperture  61  is evident in the graft material covering component  61 . The graft covering  62  may be connected to support section  63  by means of sutures, adhesives or any suitable means. Aperture  61  in the graft covering  62  may be equal in size to the aperture affected in support structure  63 . Flaring may be introduced to component ends  65  in order to better engage a body lumen (not shown) when implanted. 
         [0046]      FIGS. 15B and 15C  schematically illustrates a non-limiting embodiment of stent graft component  70  wherein component  70  may have include sections with varying diameters, so that a portion of component  70  may be deposited within a section of component  60  (not shown).  FIG. 15C  shows another embodiment wherein circumferential engagement arms  74  may be formed so as to engage portions of component  60  (not shown) so as to anchor both components together. 
         [0047]      FIGS. 16A and 16B  show the flow of blood through the joined stent graft components  60  and  70 . It is important to allow blood flow to both sides of component  60  so as not to cause ischemia.  FIG. 16B  illustrates that component  70  is not covered throughout by a graft covering so as to allow blood flow to both sides. 
         [0048]    The scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.