Abstract:
An endoluminal prosthesis for treatment of a condition in a lumen in the vicinity of a branch lumen, the lumen being adapted to resist migration, is provided. In one embodiment, the prosthesis includes a substantially tubular main stent adapted for placement in the main lumen. A substantially tubular anchor stent is connected to the main stent and adapted for placement in the branch lumen.

Description:
BACKGROUND OF THE INVENTION 
   Endoluminal graft prostheses adapted to be placed in a lumen in the vicinity of a branch lumen are typically used, for example, in the treatment of abdominal aortic aneurysms (AAAs). Once placed, such prostheses may experience changing lumen morphology. More specifically, a prosthesis deployed for treatment of an AAA may be subjected to downward forces, thereby causing the prosthesis to migrate distally (away from the heart). 
   Accordingly, there remains a need for a prosthesis suitable for placement in a lumen, in the vicinity of a branch lumen, that improves fixation and resists migration. 
   SUMMARY OF THE INVENTION 
   An endoluminal prosthesis for treatment of a condition in a body lumen near a branch lumen is adapted to resist migration. In one embodiment, the prosthesis includes a substantially tubular self-expandable main stent adapted for placement in the main lumen, or the aorta in the case of a device for treatment of an AAA. A substantially tubular anchor stent is pivotally connected to the main stent and adapted for placement in the branch lumen, or a renal artery in the case of an AAA device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates an embodiment of a deployed endovascular prosthesis (shown without a graft) comprised of a main stent and an anchor stent pivotally connected to the main stent, showing the anchor stent placed within a renal artery; 
       FIG. 2A  is a detail view of the embodiment illustrated in  FIG. 1 , showing the anchor stent in a pre-deployment configuration; 
       FIG. 2B  is detail view similar to that of  FIG. 2A , showing the anchor stent in a post-deployment configuration; 
       FIG. 3  is an expanded detail view of  FIG. 2B  in the direction of arrow “V,” showing a collar of the anchor stent slideably mounted on a substantially elbow-shaped shaft of the main stent; 
       FIG. 4A  is a representation of a delivery device comprised of a tip and a sheath for deployment of the endovascular prosthesis illustrated in  FIG. 1 ; 
       FIG. 4B  shows the delivery device illustrated in  FIG. 4A  during an early stage of deployment with the anchor stent in a pre-deployment configuration; 
       FIG. 4C  shows the delivery device illustrated in  FIG. 4A  during a later stage of deployment with the anchor stent in a post-deployment configuration; 
       FIG. 5A  illustrates a guide wire for the anchor stent advanced from an iliac artery through a renal artery; 
       FIG. 5B  illustrates a guide wire for the main stent advanced from the iliac artery through the aorta; 
       FIG. 5C  shows the delivery device represented in  FIG. 4A  advanced over the guide wires illustrated in  FIGS. 5A and 5B ; 
       FIG. 6A  shows the cone of the delivery device represented in  FIG. 4A  advanced to the supra-renal region, and the sheath partially withdrawn to partially release the main stent and the anchor stent of the endovascular prosthesis illustrated in  FIG. 1 ; 
       FIG. 6B  is a view similar to that of  FIG. 6A , showing the sheath further withdrawn and the anchor stent (in a compressed state around a balloon catheter) fully released from the sheath; 
       FIG. 6C  is a view similar to that of  FIG. 6B , showing the anchor stent advanced toward the renal artery; 
       FIG. 7A  shows the anchor stent (in a compressed state around the balloon catheter) positioned within the renal artery; 
       FIG. 7B  is a view similar to that of  FIG. 7A , showing the balloon inflated and the anchor stent in an expanded state; 
       FIG. 7C  is view similar to that of  FIG. 7B , showing the balloon deflated; 
       FIG. 8A  shows the sheath further withdrawn and the proximal portion of the main stent fully released and expanded; 
       FIG. 8B  illustrates the endovascular prosthesis (shown with a graft) deployed with the sheath fully withdrawn and the guide wires removed; and 
       FIG. 9  illustrates another embodiment of an endovascular prosthesis (shown with a graft) comprised of a main stent and an anchor stent pivotally connected to the main stent, showing the anchor stent in a pre-deployment configuration. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention. 
   Referring generally to  FIGS. 1-3  and  8 B, there is shown an embodiment of an endovascular prosthesis  10  for treatment of an abdominal aortic aneurysm (AAA) “A,” wherein the prosthesis  10  is adapted to resist migration. Prosthesis  10  includes a substantially tubular, self-expandable, bifurcated main stent  12  adapted for placement below the renal arteries “R,” the main stent  12  having a graft  14  (not shown in  FIGS. 1 and 3 ). A substantially tubular anchor stent  16  is pivotally connected to main stent  12  and adapted for placement in a renal artery “R.” 
   Anchor stent  16  is oriented substantially coaxially to main stent  12  in a pre-deployment configuration (as illustrated in  FIG. 2A ), and substantially perpendicular to main stent  12  in a post-deployment configuration (as illustrated in  FIGS. 1 ,  2 B,  3 , and  7 A- 8 B). 
     FIG. 1  illustrates a deployed endovascular prosthesis  10  (shown without a graft  14 , for clarity purposes) including a main stent  12  and an anchor stent  16  pivotally connected to main stent  12 , showing anchor stent  16  placed within one of the renal arteries “R.” Such placement of anchor stent  16  within renal artery “R” improves fixation of prosthesis  10  and resists migration. More specifically, due to changing vessel morphology, prosthesis  10  will typically be subjected to downward forces that may cause a conventional prosthesis to migrate distally (away from the heart). As represented in  FIG. 1 , axial movement of prosthesis  10  is limited by the fit of anchor stent  16  within renal artery “R.” 
   The exemplary embodiment of main stent  12  illustrated in  FIG. 1  includes a leg  18  extending within each iliac artery “I.” The construction of main stent  12  may be of any type of self-expanding stent, and the construction of anchor stent  16  is preferably of any type of balloon-expandable stent. Main stent  12  may be formed from, for example, an expandable wire structure or a laser cut metallic structure. Similarly anchor stent  16  may be formed from, for example, an expandable wire structure or a laser cut metallic structure. The structures of main stent  12  and anchor stent  16  of this embodiment may be the same or they may be different, depending upon the specific application. 
     FIG. 2A  is a detail view of prosthesis  10  showing anchor stent  16  in a pre-deployment configuration. More specifically, anchor stent  16  is oriented substantially coaxially to main stent  12  in the pre-deployment configuration. Graft  14  is represented covering a portion of main stent  12 . In the pre-deployment configuration of prosthesis  10 , main stent  12  and anchor stent  16  are each in a compressed state. However, for clarity purposes, main stent  12  and anchor stent  16  are each shown in an expanded state in  FIG. 2A . The deployment method of prosthesis  10  will be described in detail below. 
   As shown in  FIG. 2A , main stent  12  includes a substantially elbow-shaped shaft  20 , and anchor stent  16  includes a collar  22  adapted to slide along shaft  20  to effect the pivotal connection. A stopper  24  is fixed to an end of shaft  20  to limit the movement of collar  22 , and consequentially prevent anchor stent  16  from becoming detached from main stent  12 . 
   The exemplary construction of shaft  20  includes two parallel cylindrical members. Shaft  20 , however, is not limited to such an arrangement, and may include any number of members of any cross section suitable for pivotal cooperation with collar  22 . The exemplary shape of stopper  24  is spherical. Stopper  24 , however, is not limited to such a shape, and may be formed of any shape that offers the desired stopping feature. 
     FIG. 2B  is detail view similar to that of  FIG. 2A , showing anchor stent  16  in a post-deployment configuration. More specifically, anchor stent  16  is oriented substantially perpendicular to main stent  12  in the post-deployment configuration (as illustrated in  FIGS. 1 ,  2 B,  3 , and  7 A- 8 B). In the fully post-deployment configuration of prosthesis  10 , main stent  12  and anchor stent  16  are each in an expanded state. During the deployment method of prosthesis  10  (described in detail below) collar  22  slides along shaft  20  from the configuration illustrated in  FIG. 2A  to the configuration illustrated in  FIG. 2B  to effect the pivotal connection. As represented in  FIG. 2B , stopper  24  limits the movement of collar  22 , and consequentially prevents anchor stent  16  from becoming detached from main stent  12 . 
     FIG. 3  is an expanded detail view of the same area shown in  FIG. 2B , taken in the direction of arrow “V” in  FIG. 2B .  FIG. 3  shows collar  22  of anchor stent  16  slideably mounted on substantially elbow-shaped shaft  20  of main stent  12 . 
     FIGS. 4A-4C  show a delivery device  26  during various stages of deployment of prosthesis  10 . The deployment method itself will be described in detail below with reference to  FIGS. 5A-8B . 
     FIG. 4A  is a representation of delivery device  26  comprised of a tip  28  and a sheath  30  for deployment of endovascular prosthesis  10 . Sheath  30  contains prosthesis  10  (not shown), keeping self-expandable main stent  12  (not shown) in its compressed state. Delivery device  26  includes a main stent guide wire port  32 , an anchor stent guide wire port  34 , and a balloon inflation port  36 . Tip  28  of delivery device  26  includes a main stent guide wire lumen  38  in the form of an axial through-hole, and an anchor stent guide wire lumen  40  in the form of a surface groove. 
     FIG. 4B  shows delivery device  26  illustrated in  FIG. 4A  during an early stage of deployment with anchor stent  16  in a pre-deployment configuration. As in  FIG. 2A , anchor stent  16  is oriented substantially coaxially to main stent  12 . Unlike  FIG. 2A , however, main stent  12  and anchor stent  16  are each represented in a compressed state in  FIG. 4B . Sheath  30  is partially withdrawn to partially release main stent  12  and anchor stent  16  of endovascular prosthesis  10 . Balloon-expandable anchor stent  16  is in its compressed state around a balloon catheter  42 .  FIG. 4B  further illustrates the main stent guide wire  44  extending through main stent  12  and main stent guide wire lumen  38 , and the anchor stent guide wire  46  extending through anchor stent  16 . 
     FIG. 4C  shows delivery device  26  during a later stage of deployment with anchor stent  16  in a post-deployment configuration. As in  FIG. 2B , anchor stent  16  is oriented substantially perpendicular to main stent  12 . Unlike  FIG. 2B , however, main stent  12  and anchor stent  16  are each represented in a compressed state in  FIG. 4C . It is not until prosthesis  10  is fully deployed that main stent  12  and anchor stent  16  are each in an expanded state (post-deployment configuration) as illustrated in  FIG. 2B . As illustrated in  FIG. 4C , sheath  30  contains prosthesis  10 , keeping self-expandable main stent  12  in its compressed state. Sheath  30  is further withdrawn and anchor stent  16  (still in its compressed state around balloon catheter  42 ) is fully released from sheath  30 . 
   The deployment method of prosthesis  10  will be described in detail below with reference to  FIGS. 5A-8B . 
     FIG. 5A  illustrates that a first guide wire (anchor stent guide wire  46 ) is advanced from an iliac artery “I” through a renal artery “R.”  FIG. 5B  illustrates that a second guide wire (main stent guide wire  44 ) is advanced from the same iliac artery “I” through the aorta “A.”  FIG. 5C  shows that delivery device  26  is advanced over guide wires  44  and  46 . Main stent guide wire  44  extends through main stent  12  (not shown) and main stent guide wire lumen  38 , and anchor stent guide wire  46  extends through anchor stent  16  (not shown) and anchor stent guide wire lumen  40 . 
     FIG. 6A  shows that cone  28  of delivery device  26  is advanced to the supra-renal region “S.” Sheath  30  is partially withdrawn to partially release main stent  12  and anchor stent  16  of endovascular prosthesis  10 . This stage of the deployment method is similar to that described above with reference to  FIG. 4B . 
     FIG. 6B  shows that sheath  30  is further withdrawn and anchor stent  16  (in a compressed state around balloon catheter  42 ) is fully released from sheath  30 . At this stage, main stent  12  is partially deployed, yet it may be repositioned as desired. 
     FIG. 6C  shows that anchor stent  16  is advanced toward the ostium of renal artery “R.” As described above with reference to  FIG. 2B , collar  22  (not shown) of anchor stent  16  slides along shaft  20  (not shown) of main stent  12  from the configuration illustrated in  FIG. 2A  to the configuration illustrated in  FIG. 2B  to effect the pivotal connection that facilitates the advancement of anchor stent  16  toward renal artery “R.” 
   For simplicity purposes, tip  28  is not represented in  FIGS. 7A-8A .  FIG. 7A  shows anchor stent  16  (in a compressed state around balloon catheter  42 ) is positioned within renal artery “R.” This stage of the deployment method is similar to that described above with reference to  FIG. 4C . 
     FIG. 7B  shows that balloon  42  is inflated utilizing balloon inflation port  36  of delivery device  26  (represented in  FIGS. 4A-4C ) and anchor stent  16  is expanded to its expanded state.  FIG. 7C  shows that balloon  42  is deflated, leaving anchor stent  16  in its expanded state within renal artery “R.” 
     FIG. 8A  shows sheath  30  further withdrawn and the proximal portion (closest to the heart) of main stent  12  fully released and expanded. Balloon catheter  42  has been removed. 
     FIG. 8B  shows that guide wires  44  and  46  and tip  28  are removed. Sheath  30  is fully withdrawn and main stent  12  is fully released and expanded within the aorta “A.” In other words,  FIG. 8  illustrates endovascular prosthesis  10  (shown with graft  14 ) fully deployed. Legs  18  of main stent  12  are deployed within iliac arteries “I” in a conventional manner such as, for example, that disclosed in U.S. Pat. No. 6,773,453 to Ravenscroft, or by extension of a short leg with a mating stent-graft introduced through iliac “I” on the right as shown in  FIG. 8B . 
     FIG. 9  illustrates another embodiment of the endovascular prosthesis  10  (shown with a graft  14 ) including a main stent  12  and an anchor stent  16  pivotally connected to the main stent  12 , showing anchor stent  16  in a pre-deployment configuration. The configuration and deployment method of this exemplary embodiment are essentially the same as those of prosthesis  10  described above with reference to  FIGS. 1-8B , with some notable differences. Main stent  12  illustrated in  FIG. 9  is formed from a tubular member  48  rigidified by a network of channels  50  inflated by a filler material. Such a prosthesis is described, for example, in U.S. Pat. No. 5,871,537 to Holman et al., and U.S. Patent Application Publication No. US 2003/0120331 to Chobotov et al. Main stent  12  also includes a connecting ring  52 , connected to an upper wire frame or laser cut frame landing section, which is mated with anchor stent  16  as in the embodiment illustrated in  FIG. 1 . 
   Anchor stent  16 , as illustrated in  FIG. 9 , may be formed from an expandable wire structure or a laser cut metallic structure. Alternatively, anchor stent  16  may also be formed from a tubular member rigidified by a network of channels inflated by a filler material. The structures of main stent  12  and anchor stent  16  of this embodiment may be the same or they may be different, depending upon the specific application. 
   While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.