Abstract:
An introducer for an expandable endovascular prosthesis having a self expanding stent has a distal prosthesis positioning mechanism and a proximal prosthesis retention mechanism. The proximal prosthesis retention mechanism includes a cylindrical sleeve adapted to retain the self expanding stent. A release mechanism extends proximally from the distal prosthesis positioning mechanism and exerts a force in the proximal direction on an interior surface of the self expanding stent to retain the self expanding stent in the cylindrical sleeve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims all benefits of Provisional Application Ser. No. 60/503,375 filed Sep. 16, 2003. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates to a medical device and, in particular, a method and means for retaining and releasing an expandable, intraluminal prosthesis for the endovascular repair of diseased or damaged vessels. 
     Throughout this specification the terms proximal and proximally are used for a position or direction towards the patient&#39;s heart and the terms distal and distally are used for a position or direction away the patient&#39;s heart. 
     2. Related Art 
     The deployment of intraluminal prostheses into the lumen of a patient from a remote location by the use of a deployment device or introducer has been disclosed in a number of earlier patents and patent applications. U.S. Pat. No. 4,562,596 entitled “Aortic Graft, Device and Method for Performing an Intraluminal Abdominal Aortic Aneurysm Repair”, which is herein incorporated by reference, proposes the retention of a self expanding graft within a sleeve until it is to be deployed, at which time the sleeve is withdrawn and the graft is allowed to expand. U.S. Pat. No. 4,665,918 entitled “Prosthesis System and Method”, which is herein incorporated by reference, proposes a system and method for the deployment of a prosthesis in a blood vessel. The prosthesis is positioned between a delivery catheter and an outer sheath and expands outwardly upon removal of the sheath. 
     U.S. Pat. No. 4,950,227 entitled “Stent Delivery System”, which is herein incorporated by reference, proposes the delivery of a stent by mounting the stent to the outside of an inflatable catheter and retaining the ends of an unexpanded stent by fitting a sleeve over either end of the stent. Expansion of the stent is caused by inflation of the catheter between the sleeves so that the ends of the stent are withdrawn from the respective sleeves and the stent released and expanded into position. 
     U.S. Pat. No. 5,387,235 entitled “Expandable Transluminal Graft Prosthesis for Repair of Aneurysm”, discloses apparatus and methods of retaining grafts onto deployment devices. These features and other features disclosed in U.S. Pat. No. 5,387,235 could be used with the present invention, and the disclosure of U.S. Pat. No. 5,387,235 is herein incorporated by reference. 
     U.S. Pat. No. 5,720,776 entitled “Barb and Expandable Transluminal Graft Prosthesis for Repair of Aneurysm” discloses improved barbs with various forms of mechanical attachment to a stent. These features and other features disclosed in U.S. Pat. No. 5,720,776 could be used with the present invention, and the disclosure of U.S. Pat. No. 5,720,776 is herein incorporated by reference. 
     U.S. Pat. No. 6,206,931 entitled “Graft Prosthesis Materials” discloses graft prosthesis materials and a method for implanting, transplanting replacing and repairing a part of a patient and particularly the manufacture and use of a purified, collagen based matrix structure removed from a submucosa tissue source. These features and other features disclosed in U.S. Pat. No. 6,206,931 could be used with the present invention, and the disclosure of U.S. Pat. No. 6,206,931 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO99/29262 entitled “Endoluminal Aortic Stents” discloses a fenestrated prosthesis for placement where there are intersecting arteries. This feature and other features disclosed in PCT Patent Publication Number No. WO99/29262 could be used with the present invention, and the disclosure of PCT Patent Publication Number No. WO99/29262 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO03/034948 entitled “Prostheses for Curved Lumens” discloses prostheses with arrangements for bending the prosthesis for placement into curved lumens. This feature and other features disclosed in PCT Patent Publication Number No. WO03/034948 could be used with the present invention, and the disclosure of PCT Patent Publication Number No. WO03/034948 is herein incorporated by reference. 
     United States Published Patent Application No. 20030233140 entitled “Trigger Wire System” discloses release wire systems for the release of stent grafts retained on introducer devices. This feature and other features disclosed in United States Published Patent Application No. 20030233140 could be used with the present invention, and the disclosure of United States Published Patent Application No. 20030233140 is herein incorporated by reference. 
     United States Published Patent Application No. 20040098079 entitled “Thoracic Aortic Stent Graft Deployment Device” discloses introducer devices adapted for deployment of stent grafts particularly in the thoracic arch. This feature and other features disclosed in United States Published Patent Application No. 20040098079 could be used with the present invention and the disclosure of United States Published Patent Application No. 20040098079 is herein incorporated by reference. 
     United States Published Patent Application No. 20040054396 entitled “Stent-Graft Fastening” discloses arrangements for fastening stents onto grafts particularly for exposed stents. This feature and other features disclosed in United States Published Patent Application No. 20040054396 could be used with the present invention, and the disclosure of United States Published Patent Application No. 20040054396 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO03/053287 entitled “Stent Graft with Improved Graft Adhesion” discloses arrangements on stent grafts for enhancing the adhesion of such stent grafts into walls of vessels in which they are deployed. This feature and other features disclosed in PCT Patent Publication Number No. WO03/053287 could be used with the present invention, and the disclosure of PCT Patent Publication Number No. WO03/053287 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO98/53761 entitled “A Prosthesis and a Method and Means of Deploying a Prosthesis”, which is herein incorporated by reference, discloses various embodiments of an introducer for positioning an expandable endovascular prosthesis in a lumen of a patient. In one disclosed embodiment, the introducer includes a trigger wire mechanism to control the release of a proximal portion of the prosthesis. It would be desirable to provide a method and apparatus to deploy a graft prosthesis that provides a controlled release of a proximal portion of the prosthesis without the need for a trigger wire. 
     SUMMARY 
     An introducer for an expandable, endovascular prosthesis with a self expanding stent has proximal and distal prosthesis positioning mechanisms. The proximal prosthesis positioning mechanism has a cylindrical sleeve and a first control member to selectively disengage the cylindrical sleeve from the prosthesis. The distal prosthesis positioning mechanism has a distal retention section and a second control member to selectively disengage the distal retention section from the prosthesis. The first control member includes a first region coupled to the distal prosthesis positioning mechanism that extends longitudinally therefrom. The first control member also includes a second region that is coupled to the first region. The second region selectively and proximally disengages the self expanding stent to retain the self expanding stent in the cylindrical sleeve. 
     A method of placing a prosthesis into an internal lumen with an insertion assembly includes a step of inserting the insertion assembly including the prosthesis into the internal lumen and withdrawing a sheath from the insertion assembly to expose the prosthesis. A force is exerted on the prosthesis in a proximal direction by a release mechanism to retain the prosthesis in a prosthesis retention mechanism of the insertion assembly. The prosthesis retention mechanism is moved proximally away from the release mechanism to release the prosthesis from the insertion assembly. The sheath is replaced onto the insertion assembly, and the insertion assembly is retracted. 
     The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an introducer with a prosthesis partially deployed. 
         FIG. 2  is a sectional detail view of a portion of the introducer around the distal end of the prosthesis. 
         FIG. 3  is a sectional detail view of a portion of the introducer around the proximal end of the prosthesis. 
         FIG. 4  is a sectional detail view of a portion of the introducer around the haemostatic seal. 
         FIG. 5  is a sectional detail view of a portion of the introducer around the trigger wire release mechanism. 
         FIG. 6  is a sectional detail view of the introducer around the pin vise clamp and the medical reagent introduction tube. 
         FIG. 7  is a sectional view of the introducer of  FIG. 1  fully loaded and ready for introduction into a patient. 
         FIG. 8  is a side elevation view, partially in section, of the introducer of  FIG. 7  in a first stage of deployment of the prosthesis. 
         FIG. 9  is a side elevation view, partially in section, of the introducer of  FIG. 7  at the release of the proximal end stage of deployment. 
         FIG. 10  is a side elevation view, partially in section, of the introducer of  FIG. 7  at the release of the distal end stage of deployment. 
         FIG. 11  is a side elevation view, partially in section, of the introducer of  FIG. 7  showing an advancement of the distal attachment mechanism to the proximal attachment mechanism. 
         FIG. 12  is a side elevation view, partially in section, of the introducer of  FIG. 7  showing the withdrawal of the introducer from within the expanded prosthesis. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a prosthesis  20 , and an endovascular deployment system, also known as an introducer, for deploying the prosthesis  20  in a lumen of a patient during a medical procedure. The introducer includes an external manipulation section  1 , a distal positioning mechanism and attachment region  2 , and a proximal positioning mechanism and attachment region  3 . During a medical procedure to deploy the prosthesis  20 , the distal and proximal attachment regions  2  and  3  will travel through the lumen within a patient to a desired deployment site. The external manipulation section  1 , which is acted upon by a user to manipulate the introducer, remains outside of the patient throughout the procedure. 
     The prosthesis  20  comprises a tubular graft material, such as Dacron, with self expanding stents  19  attached thereto. The self expanding stents  19  cause the prosthesis  20  to expand following disengagement from the introducer. The prosthesis  20  also includes a self expanding zigzag stent  21  that extends from the prosthesis proximal end. When disengaged from the introducer, the self expanding zigzag stent  21  anchors the proximal end of the prosthesis  20  to the lumen. 
       FIG. 3  shows the proximal attachment region  3  in greater detail. The proximal attachment region  3  includes a cylindrical sleeve  10 . The cylindrical sleeve  10  has a long tapered flexible extension  11  extending from the sleeve proximal end. The flexible extension  11  has an internal longitudinal aperture  12 . The longitudinal aperture  12  facilitates advancement of the tapered flexible extension  11  along an insertion wire  13 . The aperture  12  also provides a channel for the introduction of medical reagents. For example, it may be desirable to supply a contrast agent to allow angiography to be performed during placement and deployment phases of the medical procedure. 
     A thin walled tube  15 , which can be made of metal, is fastened to the extension  11 . The thin walled tube  15  is flexible so that the introducer can be advanced along a relatively tortuous vessel, such as a femoral artery. The flexibility of the thin walled tube  15  allows manipulation longitudinally and rotationally of the proximal attachment region  3 . The thin walled tube  15  extends through the introducer to the manipulation section  1 , terminating at a connection means  16 , as shown in  FIG. 6 . 
     Regarding the introduction of reagents,  FIG. 6  shows that the connection means  16  is adapted to accept a syringe to facilitate the introduction of reagents into the thin walled tube  15 . The thin walled tube  15  is in fluid communication with the aperture  12  of the flexible extension  11 . Therefore, reagents introduced into connection means  16  can flow through the aperture  12  and emanate from the apertures  14 . 
     As shown in  FIG. 2 , a tube  41 , which can be made of a suitable plastic, is coaxial and radially outside the thin walled tube  15 . The tube  41  is “thick walled”, that is to say the thickness of the wall of tube  41  is several times that of the thin walled tube  15 . A sheath  30  is coaxial and radially outside the thick walled tube  41 . The thick walled tube  41  and the sheath  30  extend distally to the manipulation region  1 , as shown in  FIG. 4 . 
       FIGS. 2 and 3  illustrate retention, and distal and proximal release mechanisms of the introducer, respectively. During the placement phase of the medical procedure, the prosthesis  20  can be retained in a compressed condition by the sheath  30 . The sheath  30  extends distally to a gripping and haemostatic sealing means  35  of the external manipulation section  1 , shown in  FIG. 4 . 
     During assembly of the introducer, the sheath  30  can be advanced over the cylindrical sleeve  10  of the proximal attachment region  3  while the prosthesis  20  is held in a compressed state by an external force. A distal attachment (retention) section  40  is formed in the thick walled tube  41  to retain the distal end of the prosthesis  20 . Alternatively, the distal attachment section  40  can be a separate piece coupled to the thick walled tube  41 . 
     A thin walled cannula  22  is also formed in the thick walled tube  41 . Alternatively, the thin walled cannula  22  can be a separate piece coupled to the thick walled tube  41 . The thin walled cannula  22  extends from the distal attachment section  40  to a conical tip  23 . The conical tip  23  can be either coupled to the end of the thin walled cannula  22  or formed in the thick walled tube  41 . The thick walled tube  41 , the thin walled cannula  22 , and the conical tip  23  are each coaxial with and radially outside the thin walled tube  15 . 
     When the prosthesis  20  is in a compressed condition, the self expanding zigzag stent  21  is retained in the cylindrical sleeve  10  by the conical tip  23 . The conical tip  23  asserts pressure on the distal end of the self expanding stent  21  in the proximal direction, holding the self expanding zigzag stent  21  in the cylindrical sleeve  10  without the need for a trigger wire. The self expanding stent  21  is disengaged by first retracting the sheath  30 , and then sliding the proximal attachment region  3 , including the cylindrical sleeve  10 , away from the conical tip  23 . Once the cylindrical sleeve  10  has cleared the self expanding stent  21 , the stent  21  will expand. The thin walled cannula  22  and the conical tip  23  form a control member to selectively disengage the cylindrical sleeve  10  from the prosthesis  20  by exerting force on (pushing) the self expanding stent  21  into the cylindrical sleeve  10  until the prosthesis  20  is positioned at a desired site in the lumen. 
     The distal end  42  of the prosthesis  20  is retained by the distal attachment section  40  of the thick walled tube  41 . The distal end  42  of the prosthesis  20  has a loop  43  through which a distal trigger wire  44  extends. The distal trigger wire  44  extends through an aperture  45  in the distal attachment section  40  into the annular region between the thin walled tube  15  and the thick walled tube  41 . As shown in  FIG. 5 , the distal trigger wire  44  extends through the annular space between the thick walled tube  41  and the thin walled tube  15  to the manipulation region  1 . The distal trigger wire  44  exits the annular space at a distal wire release mechanism  25 . The distal trigger wire  44  and the distal wire release mechanism  25  form a control member to selectively disengage the distal retention section  40  from the prosthesis  20  when it is positioned at a desired site in a lumen of a patient. 
       FIG. 4  shows the haemostatic sealing means  35  of the external manipulation section  1  shown in greater detail. The haemostatic sealing means  35  includes a haemostatic seal  27  a side tube  29 . The haemostatic seal  27  includes a clamping collar  26  that clamps the sheath  30  to the haemostatic seal  27 . The haemostatic seal  27  also includes a seal ring  28 , which can be made of silicone. The seal ring  28  forms a haemostatic seal around the thick walled tube  41 . The side tube  29  facilitates the introduction of medical reagents between the thick walled tube  41  and the sheath  30 . 
       FIG. 5  shows a proximal portion of the external manipulation section  1 . The release wire actuation section has a body  36  that is mounted onto the thick walled tube  41 . The thin walled tube  15  passes through the body  36 . The distal wire release mechanism  25  is mounted for slidable movement on the body  36 . A clamping screw  37  prevents inadvertent early disengagement of the distal end  42  of the prosthesis  20 . A haemostatic seal  38  is provided so the trigger wire  44  can extend out through the body  36  to the release mechanism  25  without unnecessary blood loss during the medical procedure. 
       FIG. 6  shows a distal portion of the external manipulation section  1 . A pin vise  39  is mounted onto the distal end of the body  36 . The pin vise  39  has a screw cap  46 . When screwed in, the vise jaws  47  clamp against and engage the thin walled tube  15 . When the vise jaws  47  are engaged, the thin walled tube  15  can only move with the body  36 , and hence the thin walled tube  15  can only move with the thick walled tube  41 . With the screw cap  46  tightened, the entire assembly, except for the external sheath  30 , can be moved as one. 
       FIGS. 7 through 12  show the various stages of the deployment of the prosthesis  20  during the medical procedure. A guide wire  13  is introduced into a lumen such as the femoral artery and advanced until its tip is beyond the region into which the prosthesis  20  is to be deployed. 
     In  FIG. 7 , the introducer assembly is shown fully assembled ready for introduction into a patient. The prosthesis  20  is retained at each of its ends by the proximal and distal retaining assemblies respectively, and compressed by the external sheath  30 . If it is an aortic aneurism which is to be grafted, the introducer assembly can be inserted through a femoral artery over the guide wire  13  in the form as shown in  FIG. 7 , and positioned by well-known radiographic techniques (not discussed here). 
     In  FIG. 8 , the introducer assembly is in a desired position for deployment of the prosthesis  20 . The external sheath  30  is withdrawn to just proximal of the distal attachment section  40 . This action disengages the middle portion of the prosthesis  20  so that it can expand radially. The proximal self expanding stent  21 , however, is still retained within the cylindrical sleeve  10 . Also, the distal end  42  of the prosthesis  20  is still retained within the external sheath  30 . 
     By release of the pin vise  39  to allow small movements of the thin walled tube  15  with respect to the thick walled tube  41 , the prosthesis  20  can be lengthened or shortened or rotated or compressed for accurate placement in the desired location within the lumen. X-ray opaque markers (not shown) can be placed along the prosthesis  20  to assist with placement of the prosthesis. 
     In  FIG. 9 , the screw cap  46  of the pin vise  39  has been loosened so that the thin walled tube  15  can been pushed in a proximal direction to move the proximal attachment sleeve  10  in a proximal direction. When the proximal attachment sleeve  10  no longer surrounds the self expanding stent  21  at the proximal end of the prosthesis  20 , the self expanding stent  21  expands. When the stent  21  expands, the hooks or barbs  24  on the self expanding stent  21  grip into the walls of the lumen of the patient to hold the proximal end of the prosthesis  20  in place. 
     At this point, the distal end  42  of the prosthesis  20  is still retained by the distal attachment section  40 , with the loop  43  retained therein. The external sheath  30  has been withdrawn to a position distal of the distal attachment section  40  to allow the distal end  42  of the prosthesis  20  to expand. At this point, the distal end  42  of the prosthesis  20  can still be moved. Consequently, the prosthesis  20  can still be rotated or lengthened or shortened or otherwise moved to for accurate positioning. Where the prosthesis  20  to be deployed is a bifurcated graft, the movement at this stage may ensure that the shorter leg is directed in the direction of the contra-iliac artery. 
     In  FIG. 10 , the distal end  42  of the prosthesis  20  has been disengaged by removal of the distal trigger wire  44 . At this stage, the distal trigger wire release mechanism  25  and the distal trigger wire  44  can be removed completely. This removal can be accomplished by passing the distal wire release mechanism  25  over the pin vise  39  and the connection means  16 . The loop  43  of the terminal distal self expanding zigzag stent  19  is thus disengaged, and the prosthesis  20  is now free to expand to the walls of the vessel. At this point, the introducer is ready to be removed. 
     In  FIG. 11 , the first stage of removal is shown. First, the distal attachment section  40  is advanced until the conical tip  23  is received in the rear of the proximal attachment sleeve  10 . Next, the proximal attachment sleeve  10 , the tapered flexible extension  11 , and the distal attachment section  40 , including the thin walled cannula  22  and the conical tip  23 , are removed together, as shown in  FIG. 12 . 
     In  FIG. 12 , the sheath  30  has been advanced to cover the join between the proximal attachment sleeve  10  and the distal attachment section  40 . The sheath  30  can be removed with the proximal attachment sleeve  10 , the tapered flexible extension  11  and the distal attachment section  40 . Alternatively, these items could be removed separately, followed by removal of the external sheath  30 . 
     Throughout this specification, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of an item or group of items, but not the exclusion of any other item or group items. 
     While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Furthermore, although various indications have been given as to the scope of this invention, the invention is not limited to any one of these but may reside in two or more of these combined together. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.