Abstract:
The present disclosure relates to an apparatus and method for deployment of a modular stent-graft system. In one embodiment, a modular system comprises a first stent graft having a tapered zone, a second stent graft configured for insertion within the first stent graft, the second stent graft comprising a tapered zone, wherein each tapered zone has an angle of taper and the angle of taper of the tapered zone of the second stent graft is substantially the same as the angle of taper of the tapered zone of the first stent graft, and wherein when the second stent graft is disposed within the first stent graft, the tapered zone of the second stent graft conforms precisely to the tapered zone of the first stent graft.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Application Ser. No. 62/365,103 filed Jul. 21, 2016, which us incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to medical devices and more particularly to endovascular devices. 
       BACKGROUND 
       [0003]    Endoluminal prostheses may be inserted into a body lumen such as an anatomical vessel or duct for various purposes. Prostheses may maintain or restore patency in a formerly blocked or constricted passageway or they may be used for different procedures. For example, a prosthesis may include one or more stents disposed in or about a graft, and the stents may hold the graft in an open configuration to treat an aneurysm. Additionally, stents coupled to one or both ends of a graft may extend proximally or distally away from the graft to engage a healthy portion of a vessel wall away from a diseased portion of an aneurysm to provide endovascular graft fixation. 
         [0004]    Modular stent graft pieces can be deployed in stages to form a combined stent graft assembly. First, a central or main stent graft body can be deployed. Subsequently, secondary or attachment stent graft body can be deployed and positioned within the main stent graft body. 
         [0005]    One of the most common complications associated with endoluminal grafting for abdominal aortic aneurysms (“AAA”) is the stove piping effect that can occur in the overlap length into the proximal taper of a main stent graft body. It is desirable to create a stent graft assembly that reducing the stove piping effect and reduces the chance of turbulent flow of blood and possible thrombotic buildup through the main stent graft body. 
       SUMMARY 
       [0006]    According to a first aspect of the present disclosure, there is provided a modular stent graft system comprising a first stent graft having a first open end, a first cylindrical zone extending from the first open end for a first length, a tapered zone extending from the cylindrical zone for a second length, the tapered zone tapering from a first diameter to a second diameter smaller than the first diameter, and a second cylindrical zone extending from the tapered zone for a third length to a second open end, wherein the third length is greater than both the first length and the second length and the first length is greater than the second length; a second stent graft configured for insertion within the first stent graft, the second stent graft comprising a first open end, a tapered zone extending from the first open end for a first length, the tapered zone tapering from a first diameter to a second diameter smaller than the first diameter, and a cylindrical zone extending from the tapered zone to a second open end for a second length longer than the first length; wherein the first diameter of the tapered zone of the second stent graft is substantially the same as the first diameter of the tapered zone of the first stent graft, the second diameter of the tapered zone of the second stent graft is substantially the same as the second diameter of the tapered zone of the first stent graft, wherein each tapered zone has an angle of taper and the angle of taper of the tapered zone of the second stent graft is substantially the same as the angle of taper of the tapered zone of the first stent graft, wherein the second stent graft cylindrical zone is longer than the first stent graft second cylindrical zone such that when the second stent graft is disposed within the first stent graft and the tapered zones are mated, the second stent graft cylindrical zone extends beyond the second open end of the first stent graft, wherein the second stent graft comprises a first internal seal stent at the first open end of the second stent graft, the first seal stent having X proximal apices and a length, and a second internal seal stent directly adjacent and partially nesting with the first internal stent, the second seal stent having ½ X top apices and a length greater than the first seal stent; and wherein when the second stent graft is disposed within the first stent graft, the tapered zone of the second stent graft conforms precisely to the tapered zone of the first stent graft. 
         [0007]    According to a second aspect of the present disclosure, there is provided a modular stent graft system comprising: a first stent graft having a first open end, a first cylindrical zone extending from the first open end for a first length, a tapered zone extending from the cylindrical zone for a second length, the tapered zone tapering from a first diameter to a second diameter smaller than the first diameter, and a second cylindrical zone extending from the tapered zone for a third length to a second open end, wherein the third length is greater than both the first length and the second length and the first length is greater than the second length; a second stent graft configured for insertion within the first stent graft, the second stent graft comprising a first open end, a tapered zone extending from the first open end for a first length, the tapered zone tapering from a first diameter to a second diameter smaller than the first diameter, and a cylindrical zone extending from the tapered zone to a second open end for a second length longer than the first length; wherein the first diameter of the tapered zone of the second stent graft is substantially the same as the first diameter of the tapered zone of the first stent graft, the second diameter of the tapered zone of the second stent graft is substantially the same as the second diameter of the tapered zone of the first stent graft; wherein each tapered zone has an angle of taper and the angle of taper of the tapered zone of the second stent graft is substantially the same as the angle of taper of the tapered zone of the first stent graft; and wherein the second stent graft cylindrical zone is longer than the first stent graft second cylindrical zone such that when the second stent graft is disposed within the first stent graft and the tapered zones are mated, the second stent graft cylindrical zone extends beyond the second open end of the first stent graft, and wherein when the second stent graft is disposed within the first stent graft, the tapered zone of the second stent graft conforms precisely to the tapered zone of the first stent graft. 
         [0008]    According to a third aspect of the present disclosure, there is disclosed a method of deploying a modular stent graft system, the method comprising: inserting into the body a first stent graft having a first open end, a first cylindrical zone extending from the first open end for a first length, a tapered zone extending from the cylindrical zone for a second length, the tapered zone tapering from a first diameter to a second diameter smaller than the first diameter, and a second cylindrical zone extending from the tapered zone for a third length to a second open end, wherein the third length is greater than both the first length and the second length and the first length is greater than the second length; inserting into the body a second stent graft within the first stent graft, the second stent graft comprising a first open end, a tapered zone extending from the first open end for a first length, the tapered zone tapering from a first diameter to a second diameter smaller than the first diameter, and a cylindrical zone extending from the tapered zone to a second open end for a second length longer than the first length; wherein the first diameter of the tapered zone of the second stent graft is substantially the same as the first diameter of the tapered zone of the first stent graft, the second diameter of the tapered zone of the second stent graft is substantially the same as the second diameter of the tapered zone of the first stent graft, wherein each tapered zone has an angle of taper and the angle of taper of the tapered zone of the second stent graft is substantially the same as the angle of taper of the tapered zone of the first stent graft, wherein the second stent graft cylindrical zone is longer than the first stent graft second cylindrical zone such that when the second stent graft is disposed within the first stent graft and the tapered zones are mated, the second stent graft cylindrical zone extends beyond the second open end of the first stent graft, wherein when the second stent graft is disposed within the first stent graft, the tapered zone of the second stent graft conforms precisely to the tapered zone of the first stent graft. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0009]    An embodiment of the present invention will not be described by way of example with reference to the accompanying drawings, in which: 
           [0010]      FIG. 1  illustrates one example of a main stent graft body or device. 
           [0011]      FIG. 2  illustrates one example of an attachment stent graft having a flared proximal end. 
           [0012]      FIG. 3  illustrates the proximal end of the attachment stent graft shown in  FIG. 2 . 
           [0013]      FIG. 4  illustrates one example of a main stent graft body coupled to an attachment stent graft at a tapered mating area. 
           [0014]      FIG. 5  illustrates one example of a main stent graft body coupled to an attachment stent graft at a distal mating area. 
           [0015]      FIG. 6  illustrates a detailed view of the tapered mating area shown in  FIG. 4 . 
           [0016]      FIG. 7  illustrates a perspective view of the assembly of  FIG. 6 . 
           [0017]      FIG. 8  illustrates a detailed view of the distal mating area shown in  FIG. 5 . 
           [0018]      FIG. 9  illustrates a perspective view of the assembly of  FIG. 8 . 
           [0019]      FIG. 10  illustrates the flow of blood through a known stent graft assembly. 
           [0020]      FIG. 11  illustrates the flow of blood through a stent graft assembly. 
           [0021]      FIG. 12  illustrates the flow of blood through a known stent graft assembly. 
           [0022]      FIG. 13  illustrates the flow of blood through a stent graft assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    In the present application, the term “proximal” when referring to a delivery device refers to a direction that is farthest away from the operator using a delivery device, while the term “distal” refers to a direction that is generally closest to the operator using the delivery device. The proximal and distal ends of a delivery device can also be referred to as the introduction end of the delivery device and the operator end of the delivery device. The operator end of the delivery device is that portion of the device that is intended to remain outside of a patient during a procedure. When referring to the prosthesis itself relative to the delivery device, the proximal end of the prosthesis is that part of the prosthesis nearest the delivery end of the delivery device and the distal end of the prosthesis is that end that is closest to the operator end of the delivery device. When referring to the prosthesis relative to placement in the human body, the ends of the various devices and parts of devices may be referred to as the inflow end (that end that receives fluid first, and the outflow end (that end from which the fluid exits). 
         [0024]    The stent graft assembly  10  of the present invention (shown for example in  FIGS. 4-5 ) may include a main stent graft body or device  12  and a second graft body or attachment stent graft  14 . In one example, the main stent graft body  12  may be a Cook Medical Zenith Pivoting Branch Graft showing pivoting fenestrations as disclosed in U.S. Pat. Nos. 8,702,786, 8,795,349, 9,351,822, 8,870,939 and US Patent Publication No. 2014/0277335, incorporated herein in their entirety. In one example, the main stent graft body  12  or attachment stent graft  14  may be a fenestrated graft such as those shown in U.S. Pat. Nos. 9,072,621, 9,072,621, 8,523,934, 9,060,887, 8,172,895, 7,833,259, 7,413,573, 9,149,382, and US Publication Nos. 2015-0112420, 2016-0022411, incorporated herein in their entirety. In one example, the attachment stent graft  14  may be a Cook Medical Zenith AAA Stent Graft. 
         [0025]    The main stent graft body  12  and attachment stent graft  14  will now be described in greater detail.  FIG. 1  illustrates one example of a main stent graft body or device  12 .  FIG. 2  illustrates one example of an attachment stent graft  14  having a flared proximal end. In this embodiment, the main stent graft body  12  and attachment stent graft  14  may comprise a tubular body  16  of a biocompatible graft material  18  with a lumen  19  running therethrough. 
         [0026]    The main stent graft body  12  and attachment stent graft  14  may be supported with one or more stents  20  that are secured to and along the graft material  18  either along the outer surface  22  or inner surface  24  of the graft material  18  such as by sutures  26 . In one example, stent  20  may be a Z-stent. For example, stent  20  may have a distal end with a series of distal apices  28  and a proximal end with a series of proximal apices  30 . Stent  20  may also have one or more elongate struts  32  connecting the distal apices  28  to the proximal apices  30 . 
         [0027]    Suitable stents  20  for use in connection with the main stent graft body  12  or the attachment stent graft  14  described herein may be self-expanding or mechanically-expandable stents or both, and may be deployed according to conventional methodology. A self-expanding stent may be manufactured from a shape-memory alloy, such as nickel titanium alloy (Nitinol). If the stent comprises a self-expanding material such as Nitinol, the stent may be heat-set into the desired expanded state whereby the stent can assume a relaxed radially expanded configuration. The stent may be made from other metals and alloys that allow the stent to return to its original expanded configuration upon deployment, such as, for example, stainless steel, cobalt-chrome alloys, amorphous metals, and/or non-metallic materials as would be recognized by one of skill in the art. Additionally or alternatively, the main stent graft body  12  and the attachment stent graft  14  may be mechanically expanded, such as through the use of an expandable balloon placed within the lumen  19  of the stent graft and then radially outwardly expanded. 
         [0028]    The main stent graft body  12  may have a proximal end portion  34  and a distal end portion  36 , with a tapered transition portion  38  that interconnects the proximal end portion  34  and the distal end portion  36 . The distal end portion  36  may have a constant diameter and the proximal end portion  34  may have a selected larger diameter. An attachment stent  40  may be secured to the proximal end portion  34 , with the attachment stent  40  extending proximally from the graft material  18 . The attachment stent  40  may and have one or more barbs  42  configured to secure the main stent graft body  12  to a vessel wall. 
         [0029]    The main stent graft body  12  may have several additional stents  44 ,  46 ,  48 ,  50 ,  52  and  54  adjacent to the attachment stent  40 . In one example, stent  44  may be secured to the inner surface  24  of the graft material  18  in the proximal end portion  34  of the main stent graft body  12 . Stents  46 ,  48 ,  50 ,  52 , and  54  may be secured about the outer surface  22  of the graft material  18  along the length thereof. In one example, stents  46 ,  48 ,  50 ,  52 , and  54  are located distal to the attachment stent  40  and stent  44 . 
         [0030]    The proximal end portion  34  may contain a plurality of radiopaque markers (not shown) such as gold marker members for facilitating fluoroscopic visualization of the proximal end of the graft material  18 . For example, radiopaque markers may be used to place the main body stent graft  12  distal to the renal arteries (not shown). 
         [0031]    As shown in  FIG. 1 , one or more fenestrations  56  may be placed on the biocompatible graft material  18 . These fenestrations  56  may substantially align with the expected position of a branch vessel in the patient. There is, however, some variation both circumferentially and longitudinally in the position of the vessels. 
         [0032]      FIG. 2  illustrates one example of an attachment stent graft  14  having a flared proximal end  58 . The attachment stent graft  14  may be configured to pair with the main stent graft body  12 . In one example, the main stent graft body  12  is configured to receive the attachment stent graft  14  as described in greater detail below. 
         [0033]    The attachment stent graft  14  shown in  FIG. 2  may have a flared proximal end portion  58  and a distal end portion  62 . The distal end portion  62  may have a constant diameter and the flared proximal end portion  58  may have a selected larger diameter. The distal end portion  62  may be a unibody tube (as shown), or it may be a bifurcated stent graft having a body portion and two or more legs. In one example, the bifurcated stent graft comprises a shorter leg and a longer leg. 
         [0034]    The attachment stent graft  14  may have several stents  66 ,  68 ,  70 ,  72 ,  74 , and  76  which may be secured to the graft material  18  along the length of the attachment stent graft  14 . In one example, a first stent  66  and a second stent  68  may be secured to the inner surface  24  of the graft material  18  near the flared proximal end portion  58 . In one example, additional stents  70 ,  72 ,  74 , and  76  may be secured about the outer surface  22  of the graft material  18 . 
         [0035]    Importantly, the proximal end of the attachment stent graft  14  may have a flared proximal end portion  58 . In one example, the flared portion  58  may complement or conform to the transition portion  36  on the interior of the main stent graft body  12 . For example, as seen comparing  FIGS. 1 and 2  side by side, the flared proximal end  58  of the attachment stent graft  14  and the transition portion  36  of the main stent graft body  12  are similar in shape. The complementary flared proximal end  58  of the attachment stent graft  14  and the transition portion  36  of the main stent graft body  12  may allow a better mating area between the main stent graft body  12  and the attachment stent graft  14  (as described below and shown in  FIGS. 4-9 ). 
         [0036]      FIG. 3  illustrates the proximal end of the attachment stent graft shown in  FIG. 2 . In one example, the flared proximal end portion  58  of the attachment stent graft  14  may have a stacked stent arrangement  78 . The stacked stent arrangement  78  may be located in the flared proximal end  58  of the attachment stent graft  14 . The stacked stent arrangement  78  may allow for a tighter seal when the attachment stent graft  14  is placed into a lumen  19  in the main stent graft body  12 . 
         [0037]    In one example of a stacked stent arrangement  78 , a first stent  66  and a second stent  68  are mounted on an interior surface  24  of the graft material  18  in the attachment stent graft  14 . The first stent  66  and second stent  68  may be formed as a wire ring that has proximal and distal generally curved apex portions (apices)  30 ,  28  separated from each other by intermediate generally straight portions called struts  32 . 
         [0038]    First stent  66  and second stent  68  may not have the same proximal to distal length. For example, as illustrated in  FIG. 3  the second stent  68  has a shorter proximal-distal length than the first stent  66 . In another embodiment (not shown), the first stent  66  and the second stent  68  may have the same proximal to distal length. 
         [0039]    In one embodiment the first stent  66  and second stent  68  may overlap axially such that the stents apices of the second stent  68  nest within the apices of the first stent  66 . In another embodiment the first stent  66  and second stent  68  do not overlap or nest. For example, the first stent  66  and second stent  68  do not overlap axially, but are very close together. In one example, the first stent  66  is located slightly distal to the second stent  68 . 
         [0040]    In one embodiment (not shown), each of the proximal apices  30  of the first stent  66  may be circumferentially offset from each of the proximal apices  30  of the second stent  68 . In another example, each of the distal apices  30  of the first stent  66  may be circumferentially offset from each of the distal apices  30  of the second stent  68 . In another example, the first stent  66  and the second stent  68  comprise identical geometries. The two stents  66  and  68  may be arranged in an out-of-phase alignment or may be in-phase alignment. The first stent  66  and second stent  68  may have any configuration and geometry as disclosed in U.S. Pat. No. 8,728,145, which is incorporated by reference herein. 
         [0041]    The attachment stent graft  14  and the main stent graft body  12  may be coupled or connected.  FIGS. 4 and 5  illustrate two examples of a main stent graft body  12  coupled to an attachment stent graft  14 . 
         [0042]    In one example, the attachment stent graft  14  may have a reduced diameter delivery configuration (not shown) and a deployment configuration. When in the delivery configuration, the attachment stent graft  14  can be deployed into a lumen  19  in the main stent graft body  12 . 
         [0043]    The attachment stent graft  14  can be positioned and deployed to any location along the length of the main stent graft body  12 . In this way, the stent graft assembly  10  may be any suitable customizable length. For example, if the attachment stent graft  14  is placed in a more proximal location of the main stent graft  12 , the total length of the stent graft assembly  10  may be shorter. If the attachment stent graft  14  is placed in a more distal location on the main stent graft  12 , the total length of the stent graft assembly  10  may be longer. 
         [0044]    When in a deployed state, the attachment stent graft  14  may expand and conform to the shape of the interior of the main stent graft body  12 . 
         [0045]      FIG. 4  illustrates one example of a main stent graft body  12  coupled to an attachment stent graft  14  at a tapered mating area  80 . As illustrated in  FIG. 4 , the flared proximal end  58  of the attachment stent graft  14  may be coupled to the main stent graft body  12  at a tapered mating area  80 . The tapered mating area  80  may be located in the area just distal of fenestrations  56 . A portion of the tapered mating area  80  may be in the tapered transition portion  38  that interconnects the proximal end portion  34  and the distal end portion  36  of the main stent graft body  12 . The flared proximal end  58  of the attachment stent graft  14  may conform to the shape of the tapered transition portion  38  of the main stent graft body  12 . 
         [0046]    The radial force of the stacked stent arrangement  78  may hold the attachment stent graft  14  tightly against the interior of the main stent graft body  12 . In this way, there is a tight seal between the attachment stent graft  14  and the main stent graft body  12 . As described in more detail below, this tight seal can prevent turbulent vascular flow through the lumen  19  of the stent graft assembly  10 . 
         [0047]      FIG. 5  illustrates one example of a main stent graft body  12  coupled to an attachment stent graft  14  at a distal mating area  82 . As illustrated in  FIG. 5 , the flared proximal end  58  of the attachment stent graft  14  may be coupled to the main stent graft body  12  at a distal mating area  82 . The distal mating area  82  may be in the distal end portion  36  of the main stent graft body. 
         [0048]      FIG. 6  illustrates a close up of the tapered mating area  80  shown in  FIG. 4 . The attachment stent graft  14  may be disposed in the lumen  19  of the main stent graft body  12 . In this example, the flared proximal end  58  of the attachment stent graft  14  is disposed in the main stent graft body  12  in the tapered mating area  80 . The stacked stent arrangement  78  mounted on the interior graft  24  in the flared proximal end  58  of the attachment stent graft  14  may be at the same longitudinal level as stent  48  on the main stent graft body  12 . 
         [0049]      FIG. 7  illustrates a perspective view of the assembly of  FIG. 6 . The main stent graft body  12  may have a lumen  19  extending therethrough. The attachment stent graft  14  may be disposed in the lumen  19  of the main stent graft body  12 . A stacked stent arrangement  78  may be disposed on the flared proximal end  58  of the attachment stent graft  14 . 
         [0050]    As shown in  FIG. 7 , the shape of the flared proximal end  58  of the attachment stent graft  14  and the tapered transition portion  38  of the main stent graft body  12  are complimentary such that a tight seal can be created between the main stent graft body  12  and the attachment stent graft  14 . As will be described in greater detail below, a tight seal can prevent turbulent vascular flow through the lumen  19  of the assembly  10 . 
         [0051]      FIG. 8  illustrates a detailed view of the distal mating area  82  illustrated in  FIG. 5 . The attachment stent graft  14  may be disposed in the lumen  19  of the main stent graft body  12 . In this example, the flared proximal end  58  of the attachment stent graft  14  is disposed in the main stent graft body  12  in the distal mating area  82 . 
         [0052]    As shown in  FIG. 8 , a stent  54  on the distal portion  36  of the main stent graft body  12  may be located on the outer surface of the main stent graft body  12 . The attachment stent graft  14  may have a stacked stent arrangement  78  mounted on an interior surface  24  of the flared proximal end  58  of the attachment stent graft  14 . The stacked stent arrangement  78  may be at the same longitudinal level as a stent  54  on the distal portion  36  of the main stent graft body  12 . 
         [0053]      FIG. 9  illustrates a perspective view of the assembly of  FIG. 8 . The main stent graft body  12  may have a lumen  19  extending therethrough. The attachment stent graft  14  may be disposed in the lumen  19  of the main stent graft body  12 . A stacked stent arrangement  78  may be disposed on the flared proximal end  58  of the attachment stent graft  14 . In this example, the attachment stent graft  14  is disposed at the distal end portion  36  of the main stent graft body  12 . 
         [0054]    As shown in  FIG. 9 , a tight seal can be created between the main stent graft body  12  and the attachment stent graft  14 . As will be described in greater detail below, a tight seal can prevent turbulent vascular flow through the lumen  19  of the stent graft assembly  10 . 
         [0055]      FIG. 10  illustrates the flow of blood through a known stent graft assembly  110  where a main stent graft body  112  is coupled to a conventional attachment stent graft  114  at a distal mating area  182 . As shown in  FIG. 10 , blood flow  84  can travel in a proximal  86  to distal  88  direction through the lumen  119  of the main stent graft body  112 . A conventional attachment graft  114  may be disposed in the lumen  119  of the main stent graft body  112 . The seal between the conventional attachment graft  114  and the main stent graft body  112  may not be very tight and stove piping may occur. When stove piping occurs, the blood flow  84  may be turbulent at the transition between the main stent graft body  112  and the conventional attachment graft  114 . As shown in  FIG. 10 , the blood flow may not take a straight path through the lumen of the stent graft assembly  10  but rather may get caught in a gap  190  in a distal mating area  182 . 
         [0056]      FIG. 11  illustrates the flow of blood  84  through a stent graft assembly  10  of the present disclosure where a main stent graft body  12  is coupled to an attachment stent graft  14  at a distal mating area  82  wherein the proximal end of the attachment stent graft has a stacked stent arrangement. As shown in  FIG. 11 , a tight seal created by the stacked stent arrangement  78  in the attachment stent graft  14  can allow for blood to flow in a relatively straight path in a proximal  86  to distal  88  direction. The tighter seal can reduce the stove piping effect that can be seen with conventional devices. It can also reduce the risk of turbulent blood flow and also reduces the risk for thrombolytic build-up at a seal area  82 . The tighter seal created by the stacked stent arrangement  78  can also allow a constant seal. The stacked stent arrangement  78  at the proximal end of the attachment stent graft  14  can be flexible and adjustable and allow for deep connection delivery of grafts. 
         [0057]      FIG. 12  illustrates the flow of blood through a known stent graft assembly  10  where a main stent graft body is coupled to an attachment stent graft at a tapered mating area. As shown in  FIG. 12 , a conventional attachment stent graft  14  may have a straight proximal end  192  (as opposed to the tapered proximal end shown in this disclosure at  FIGS. 2-4 ). As a result, a gap  190  may occur between the tapered transition area  138  on the main stent graft body  12  and the proximal end  192  of the conventional attachment stent graft  14 . Blood flowing through the assembly  10  may not take a straight path through the lumen of the stent graft assembly  10  but rather the blood may get caught in a gap  190  in a seal area  180 . This gap can create a turbulent blood flow. 
         [0058]      FIG. 13  illustrates the flow of blood through a stent graft assembly  10  where a main stent graft body  12  is coupled to an attachment stent graft  14  at a tapered mating area  80  wherein the flared proximal end  58  of the attachment stent graft  14  is tapered and has a stacked stent arrangement. In this arrangement, the tapered proximal portion  58  of the attachment stent graft  14  may create a tight seal with the tapered transition portion  38  of the main stent graft body  12 . 
         [0059]    As shown in  FIG. 13 , the tighter seal created by the stacked stent arrangement  78  and the tapered proximal portion  58  of the attachment stent graft  14  can allow for blood to flow in a relatively straight path in a proximal  86  to distal  88  direction. The tighter seal can reduce the stove piping effect that can be seen with conventional devices. It can also reduce the risk of turbulent blood flow and also reduces the risk for thrombolytic build-up at a seal area  80 . The tighter seal created by the stacked stent arrangement  78  and tapered transition portion  58  can also allow a constant seal. The stacked stent arrangement  78  and the tapered proximal portion  58  of the attachment stent graft  14  can be flexible and adjustable and allow for deep connection delivery of grafts. 
         [0060]    While various embodiments of the invention have been described, the invention is not to be restricted except in light of the attached claims and their equivalents.