Abstract:
The present invention provides a guidewire placement system for delivery of an aneurysm graft limb. The invention is directed toward placement of grafts in abdominal aortic aneurysms where delivery of a contra-lateral limb is heretofore particularly difficult. The present invention provides external tubing which may be steered along with guide tubing having wire loops at the distal end thereof. The design of the external tubing and the guide tubing allow a contra-lateral guidewire to be directed toward and placed within a graft of the aneurysm. This allows for subsequent placement of a contra-lateral limb in an efficient and minimally invasive manner.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the placement of aneurysm grafts and the instruments necessary to accomplish such placement. In particular, the present invention provides a guide steering device having exposable wire loops and a steering system for placement of an aneurysm graft limb. 
     BACKGROUND OF THE INVENTION 
     As shown in FIG. 1, an abdominal aneurysm graft  80  is used to allow blood to bypass the site of an abdominal aortic aneurysm  61  and pass to iliac vascular branches  62  there from without obstruction or backflow. The abdominal aneurysm graft  80  has a main body  64  and is bifurcated into ipsilateral  66  and contra-lateral  67  limbs at its proximal end. The limbs ( 66 ,  67 ) are meant for placement within iliac vascular branches  62  which branch off from the abdominal aorta  69 . 
     In the last several years, the field of minimally invasive surgery has grown exponentially. As a result, even stent and graft placement has been affected. Presently, placement of an abdominal aneurysm graft  80  is accomplished by way of a minimally invasive catheterization technique. A guidewire  68  is inserted through a patient&#39;s vasculature and eventually through an iliac vascular branch  62  to the site of the aortic aneurysm  61 . A balloon catheter (not shown) equipped with a capsule containing the aneurysm graft to be placed is delivered to the site of the aneurysm via the guidewire  68 . The balloon portion of the catheter and the capsule are separable in order to deploy the main body  64 . 
     Once the main body  64  is deployed, the balloon portion of the catheter may be positioned within the deployed main body  64 . The balloon may then be inflated in order to anchor the main body  64  against the walls of the abdominal aorta  69  above the iliac bifurcation  71 . Surgical hooks (not shown) may be provided at an outer portion of the main body  64  to promote its anchoring against the walls of the abdominal aorta  69  during this inflation. 
     As the main body  64  is deployed, an ipsilateral limb  66  may be exposed as attached to the main body  64 . If this is the case, only a contra-lateral limb  67  will need to be added to the main body  64  in order to complete bypass of the aortic aneurysm  61  through the opposite (i.e. contra-lateral) iliac vascular branch  62 . On the other hand, if the ipsilateral limb  66  is not initially provided as attached to the main body  64 , it may be desirable to add it once the main body  64  is secured within the aortic aneurysm  61 . Again, placement of the ipsilateral limb  66  is necessary to complete bypass of the aortic aneurysm  61  via the iliac vascular branch  62  through which the catheter has initially been introduced to the site. 
     If complete bypass via iliac vascular branches  62  is desired at this point, there is still a need to attach at least one graft limb subsequent to deployment of the main body  64 . As indicated above, placement of the ipsilateral limb  66  is accomplished by either providing the ipsilateral limb  66  simultaneous with the main body  64  or by subsequently advancing the ipsilateral limb  66  to the site of the main body  64  via the guidewire  68  which has already been delivered. However, neither of these options is available for placement of the contra-lateral limb  67 . Rather, it is necessary to have a separate guide for a separate advancement of the contra-lateral limb  67  to the site of the main body  64 . Unfortunately, it is very difficult to reach an implanted main body  64  in order to guide and subsequently attach the contra-lateral limb  67 . This is because the aortic aneurysm  61  has a width which is much greater than either of the iliac vascular branches  62 . Thus, once a limb delivering mechanism, such as a catheter adapted therefore, is advanced through an iliac vascular branch  62  to the site of the aortic aneurysm  61 , it must traverse the aortic aneurysm  61  in an unguided manner and enter the main body  64  in order to subsequently deliver the contra-lateral limb  67 . 
     The difficulty associated with placement of a contra-lateral limb  67  has been addressed by simply blocking off one of the iliac vascular branches  62  and utilizing a graft which is equipped with only the ipsilateral limb  66 . However, this requires a subsequent more invasive surgical procedure to place a femoro-femoral bypass between the iliac vascular branches  62  in order to redeliver a flow of blood to the blocked iliac branch, proximal (i.e. below) the aortic aneurysm  61 . Thus, many of the advantages of minimally invasive surgery have been lost. Alternatively, a second guidewire may be inserted through a patient&#39;s vasculature distal of the aortic aneurysm  61  and through the main body  64 . Thus, once the entire abdominal aneurysm graft  80  is deployed, a guidewire will be present through both iliac branches. One or both of these guidewires may be used to aid in subsequent placement of limbs ( 66 ,  67 ). However this is a more complex procedure which requires additional incisions above (or distal) the aortic aneurysm  61  for external maintenance of the additional guidewire and introduction of the abdominal aneurysm graft  80 . Lastly, an abdominal aneurysm graft  80  may be used without limbs ( 66 ,  67 ) at all. However, such an abdominal aneurysm graft  80  is not highly stable and does not provide an efficient bypass. 
     Therefore, what is desired is a system for placement of a contra-lateral aneurysm graft limb in a minimally invasive manner via a minimal number of incisions. It may be desirable to develop a system capable of delivering a second guidewire to the site of an aneurysm to aid in subsequent placement of a graft limb without requiring additional incisions above (or distal) the aneurysm. 
     SUMMARY OF THE INVENTION 
     The present invention provides a guidewire placement system for delivery of an aneurysm graft limb. The system may include steerable external tubing with an advanced flexible region which may be directed by manipulation of a steering wire. 
     The guidewire placement system may include guide tubing. The guide tubing is equipped with wire loops at a distal end thereof to promote accessibility of an aneurysm graft during guidewire placement. 
     The present invention also provides a method of providing a contra-lateral limb to a graft. The method may involve advancement of external tubing to the site of an aneurysm and graft while manipulating a steering wire which promotes movement of a distal extension of the external tubing toward a proximal contra-lateral portion of the graft. 
     The method may involve use of guide tubing. The guide tubing is advanced to the site of an aneurysm and graft where the tubing is further advanced into the graft followed by delivery of a guidewire. 
     The present invention provides a system for graft delivery to an aneurysm. The system may include a graft and a limb deployment catheter as well as means for advancing a contra-lateral guidewire into a placed graft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross section view of an abdominal aneurysm graft of the prior art. 
     FIG. 2 is a cross sectional view of an abdominal aortic aneurysm having a graft deployed therein. 
     FIG. 3 is a side sectional view of the steerable guidewire system of one embodiment of the present invention. 
     FIG. 4A is a cross sectional view of an abdominal aortic aneurysm having a graft deployed therein and the steerable guidewire system of the present invention. 
     FIG. 4B is a cross sectional view of an abdominal aortic aneurysm having a graft deployed therein and the steerable guidewire system of the present invention. 
     FIG. 4C is a cross sectional view of an abdominal aortic aneurysm having a graft deployed therein and the steerable guidewire system of the present invention with guide tubing being deployed. 
     FIG. 4D is a cross sectional view of an abdominal aortic aneurysm and a graft deployed therein with an exposed steerable guidewire system. 
     FIG. 5 is a cross sectional view of an abdominal aortic aneurysm and a graft deployed therein with a guidewire having been advanced through a steerable guidewire system. 
     FIG. 6 is a cross sectional view of an abdominal aortic aneurysm having a graft deployed therein with extension limbs running therefrom into iliac arteries. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description makes reference to numerous specific details in order to provide a thorough understanding of the present invention. However each specific detail need not be employed to practice the present invention. Additionally, well-known details, such as particular materials or methods, have not been described in order to avoid unnecessarily obscuring the present invention. 
     Aneurysm graft placement is accomplished by way of a catheter which houses an aneurysm graft. Limbs which extend from the graft into arterial branches are often difficult to manipulate and in need of stable placement. 
     Referring to FIG. 2, an abdominal aneurysm  10  is shown. A graft  13  has been deployed within the abdominal aneurysm  10 . An ipsilateral extension limb  15  is shown extending from a main body  17  of the graft  13 . The ipsilateral extension limb  15  may have been attached to and deployed simultaneous with the main body  17 . Alternatively, the ipsilateral extension limb  15  may be separately advanced to the main body  17  of the graft  13  via the ipsilateral guidewire  30 . 
     The graft  13  is equipped with an anchoring region  20  having hooks (not shown) capable of circumferentially anchoring the graft  13  above the site of the aneurysm  10 . The anchoring region  20  is disposed above the aneurysm  10  and below renal arteries  24 . The ipsilateral extension limb  15  may have an attachment region  21  equipped with small hooks (not shown) capable of circumferentially attaching the ipsilateral limb  15  to a proximal ipsilateral portion  23  of the main body  17 . However, small hooks will not be necessary where the ipsilateral extension limb  15  has been attached to and deployed simultaneous with the main body  17 . 
     As shown in FIG. 2, a graft  13  has been delivered to the site of an abdominal aneurysm  10  with a bypass of the ipsilateral iliac artery  11  complete. This degree of bypass may be completed by advancement of such a graft  13  and ipsilateral limb  15  simultaneously to the site of the aneurysm  10  with a graft deployment balloon catheter capable of delivering such (not shown). Alternatively, this degree of bypass maybe completed by advancement of the ipsilateral limb  15  subsequent to the delivery of the main body  17 . The graft deployment balloon catheter is advanced to the site of the aneurysm  10  by way of an ipsilateral guidewire  30 . The ipsilateral guidewire  30  has been advanced to the site of the aneurysm  10  and into the aorta  33  via a femoral portion of the ipsilateral iliac artery  11 . 
     A balloon of the graft deployment balloon catheter (not shown) may aid in the placement of the graft  13  and ipsilateral limb  15 . That is, the balloon may be positioned within the main body  17 , inflated, and advanced proximally to within the ipsilateral limb  15 . This inflation and advancement forces open the main body  17  and the ipsilateral limb  15  and helps secure these features in place. 
     If the ipsilateral limb  15  is to be delivered and deployed separate from the graft  13 , this may be done by a separate advancement of a limb deployment balloon catheter (not shown) along the same ipsilateral guidewire  30 . Such a separate delivery and deployment may be desirable in order to maintain a low profile and ease advancement of the graft deployment balloon catheter. That is, the graft deployment balloon catheter would have less to deliver and thus be capable of having a smaller diameter, which would ease its advancement through the ipsilateral iliac artery  11 . 
     As shown in FIG. 2, bypass of the aneurysm  10  is not complete. In order to complete the bypass, a contra-lateral limb  16  (see FIG. 6) must still be delivered to the graft  13  and into the contra-lateral iliac artery  12 . 
     FIG. 3 reveals a side sectional view of the steerable guidewire placement system  25  of one embodiment of the present invention. The guidewire placement system  25  is capable of delivering a contra-lateral guidewire  26  to a proximal contra-lateral portion  28  of the graft  13  is shown (see also FIG.  6 ). Delivery of this contra-lateral guidewire  26  allows subsequent advancement of a limb deployment balloon catheter (not shown) to the graft  13  and deployment of a contra-lateral limb  16  thereat (see also FIG.  6 ). The proximal contra-lateral portion  28  may have a length different from that of the proximal ipsilateral portion  23 . Different lengths of the proximal portions ( 28 ,  23 ) may be desired for various reasons such as for ease of packing of the graft  13  prior to deployment. 
     The guidewire placement system  25  is equipped with external tubing  34 . In one embodiment, the external tubing  34  has a diameter in a range of approximately 0.120 to 0.156 inches and has a length of approximately 112 centimeters. The external tubing  34  may be of a thermoplastic elastomer resin such as PEBAX®. 
     The guidewire placement system  25  may also include an advanced flexible region  40 . The advanced flexible region  40  may be located near the distal end of the external tubing  34 . The advanced flexible region  40  is more flexible than its immediately surrounding portions of the external tubing  34 . The advanced flexible region  40  may be a portion of the external tubing  34  which utilizes a compression spring in place of PEBAX® or a like material which makes up surrounding portions of the external tubing  34 . In one embodiment, a compression spring having about five coils may be used. The advanced flexible region  40  may have an accordion configuration. In another embodiment, the advanced flexible region  40  may be a thinner portion of the external tubing  34  (i.e. in comparison to proximal tubing  60  proximal thereto), with or without a compression spring disposed therein. In yet another embodiment, the advanced flexible region  40  may have a diameter in the range of approximately 0.021 to 0.206 inches and a length of approximately 0.940 inches long. 
     Steering wire  41  is provided to the external tubing  34 . The steering wire  41  may be stainless steel or a nickel titanium alloy (commercially referred to as “nitinol”). In one embodiment, the diameter of the steering wire  41  may be in a range of approximately 0.010 and 0.014 inches in diameter. This range of diameter allows for visualization via fluoroscopy during a surgical procedure and avoids kinking of the wire  41 . The steering wire  41  is secured at an attachment site  42  distal of the advanced flexible region  40 . The portion of the external tubing  34 , distal of the advanced flexible region  40 , is referred to here as the distal extension  50 . 
     The attachment site  42  may simply be a hole or a post through, or about, which the steering wire  41  may be secured. Additionally, the attachment site  42  may be a location at which the steering wire  41  has been bonded to the external tubing  34 , with or without use of an adhesive. A wire channel  44  is present through the external tubing  34  at a location proximal the advanced flexible region  40 . The steering wire  41  is external to the external tubing  34  between the attachment site  42  and the wire channel  44 . 
     The steering wire  41  is threaded through the wire channel  44  and travels proximally within the external tubing  34 , eventually exiting the external tubing  34  at a proximal end thereof where it may be manipulated by a physician. That is, the physician&#39;s manipulation of the steering wire  41  at a proximal end thereof is capable of causing the external tubing  34  to bend at the advanced flexible region  40 . The distal extension  50  is the portion of the external tubing  34  which moves as the advanced flexible region  40  bends in response to the physician&#39;s manipulation of the steering wire  41 . Placement of the attachment site  42  and the wire channel  44  as indicated focuses the force resulting from the manipulation of the steering wire  41  on the advanced flexible region  40  causing it to bend in this manner. 
     The external tubing  34  of FIG. 3 is shown cross sectioned and enveloping guide tubing  35 . The guide tubing  35  may allow the external tubing  34  to enter the main body  17  (see FIG.  4 D). The guide tubing  35 , having a guide lumen  48  there through may be made of various materials such as a thermoplastic elastomer or a high density polyethylene (HDPE). The guide tubing  35  may have a diameter in the range of approximately 0.050 to 0.080 inches and a length of approximately 160 centimeters. The guide tubing  35  is capable of lateral movement within the external tubing  34 . 
     Wire loops  37  are disposed at the distal end of the guide tubing  35 . The wire loops  37  may again be stainless steel or nitinol wire having a diameter in the range of approximately 0.010 to 0.014 inches in diameter. The wire loops  37  may include loops set perpendicular to one another. The wire loops  37  may play a significant role in advancement of the external tubing  34  to within the main body  17  (see also FIG.  4 D). 
     FIGS. 4A-4D and  5  illustrate how the guidewire placement system  25  may be used. As shown in FIG. 4A, the external tubing  34  is inserted through a femoral artery and advanced through the contra-lateral iliac artery  12  to the site of the abdominal aneurysm  10 . In one embodiment the external tubing  34  is advanced to this position it may be equipped with a filling wire (not shown) to block off its guidewire lumen  46  (see FIG.  3 ). Filling wire may be used to prevent accumulation of blood and bodily fluids within the guidewire placement system  25  and may also help avoid accidental coring of vasculature as the guidewire placement system  25  is advanced. Alternatively, the guide tubing  35  maybe present within the guidewire lumen  46  during insertion (see FIG.  3 ). However, in such a situation, the loops  37  should be kept entirely within the guidewire lumen  46  during insertion in order to prevent damage to vasculature as the guidewire placement system  25  is advanced. 
     The goal of the guidewire placement system  25  is to reach the proximal contra-lateral portion  28  of the graft  13  so that a contra-lateral guidewire  26  may be delivered. Referring to FIG. 4B, a manner of steering the external tubing  34  is shown. This steering capability enhances the ability of the external tubing  34  to reach the proximal contra-lateral portion  28  of the graft  13 . Without steering (or wire loops  37 ) it is very difficult for the physician to direct the external tubing  34  to the precise location of the proximal contra-lateral portion  28 . 
     Steering is accomplished by the physician&#39;s manipulation of the steering wire  41  which acts to create an angle at the advanced flexible region  40  of the external tubing. Additionally, the physician has the ability to control the direction of the angle at the advanced flexible region  40  by rotating the external tubing  34  at a proximal end thereof. Thus, if the physician&#39;s manipulation of the steering wire  41  has caused the distal extension  50  to bend toward the ipsilateral limb  15  in an undesired manner, the external tubing  34  may be rotated to cause the distal extension  50  to point toward the proximal contra-lateral portion  28  as desired. 
     For safety, a protective drape  90  may be provided over the steering wire  41 . The protective drape  90  would tightly attach to the external tubing  34  on each side of the steering wire  41 . The protective drape  90  may also be attached to the external tubing  34  distal the attachment site  42  and proximal the wire channel  44  (see also FIG.  3 ). The protective drape  90  would be flexible enough to allow flexure of the advanced flexible region  40  and loose enough to allow the external tubing  34  to remain un-flexed if desired. The protective drape  90  encases the steering wire  41  between the external tubing  34  and the protective drape  90 . This helps prevent damage to surrounding vasculature by a possibly otherwise exposed and unprotected steering wire  41 . 
     A lock (not shown) may be provided proximal of the advanced flexible region  40 . Use of the lock allows the physician to release the steering wire  41  without causing a change in the bent angle of the advanced flexible region  40 . That is, once the physician has bent the external tubing  34  to a desired angle at the advanced flexible region  40 , the lock may be used to secure the angle. Securing the angle allows the physician to release the steering wire  41  and concentrate efforts elsewhere. 
     Referring to FIG. 4C, another manner of enhancing the ability of the external tubing  34  to reach the proximal contra-lateral portion  28  of the graft  13 , is shown. Once the guidewire placement system  25  has been advanced into the aneurysm body  52 , any filling wire (not shown) will be removed, and replaced with guide tubing  35 , if not already present. The guide tubing  35  may be advanced distally forcing the wire loops  37  out of the guidewire lumen  46  and exposing them to the aneurysm body  52 . The wire loops  37  aid the advancement of the external tubing  34  into the proximal contra-lateral portion  28  in two ways. The wire loops  37  may come into contact with the wall  53  of the aneurysm  10  and prevent the guide tubing  35  from doing the same. Thus, the guide tubing  35  is kept relatively centered within the aneurysm body  52  (i.e. and in closer proximity to the proximal contra-lateral portion  28 ). The wire loops  37  are capable of catching and holding open the proximal contra-lateral portion  28 . Rotating the guide tubing  35  at a proximal end thereof may enhance this capability. The rotation of the guide tubing  35  may cause a rotation of the wire loops  35  and thus, encourage their entry into the proximal contra-lateral portion  28 . 
     Referring to FIG. 4D, a partial cross sectional view of the graft  13  is shown such that the inside of the proximal contra-lateral portion  28  can be seen. The wire loops  37  are shown within the proximal contra-lateral portion  28 . The wire loops  37  keep the proximal contra-lateral portion  28  open and not collapsed. Thus, the external tubing  34  may easily be advanced into the proximal contra-lateral portion  28 . 
     Referring to FIG. 5, another partial cross sectional view of the graft is shown such that the inside of the proximal contra-lateral portion  28  may be seen. Once the external tubing  34  has been advanced to within the proximal contra-lateral portion  28  the guide tubing  35  may be removed. The external tubing  34  may then be used as a conduit for advancing a contra-lateral guidewire  26 . The contra-lateral guidewire  26  may have a diameter of approximately 0.035 inches. The external tubing  34 , directs the contra-lateral guidewire  26  safely to the graft  13 . The guide tubing  35  (see FIG. 4D) has been replaced with the contra-lateral guidewire  26 . The contra-lateral guidewire  26  has been delivered within the contra-lateral portion of the graft  13 . 
     Referring to FIG. 6, once a contra-lateral guidewire  26  is within the contra-lateral portion of the graft  13 , a contra-lateral limb  16  may be delivered. The contra-lateral limb  16  may be delivered along with the contra-lateral guidewire  26  via conventional means such as with a balloon catheter (not shown) equipped with a capsule containing the contra-lateral limb  16 . The contra-lateral limb  16  may have small hooks (not shown) at a distal region  70  for attachment to the proximal contra-lateral portion  28 . Once the contra-lateral limb  16  is deployed, the graft  13  is complete within the abdominal aneurysm. 
     Although an exemplary embodiment of the invention has been shown and described in the form of a steerable and centering guidewire placement system, many changes, modifications, and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention. For example, the present invention would be applicable to any guidewire placement system in which the area for guidewire placement was difficult to access.