Abstract:
A stent graft delivery device ( 10 ) has an indwelling catheter ( 26 ) extending from a handle ( 12 ) through a pusher lumen and a stent graft lumen outside the guide wire catheter ( 32 ) of the delivery device towards the nose cone dilator ( 16 ). The indwelling catheter comprises a material able to transmit rotational and longitudinal movement (advancement and withdrawal) from the distal end to the proximal end thereof and a more flexible tip ( 24 ). The indwelling catheter facilitates catheterization of a branch artery.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of provisional application Ser. No. 61/000,019, filed Oct. 23, 2007. 
    
    
     TECHNICAL FIELD 
     This invention relates to a device for delivery of a stent graft into the human or animal vasculature by endovascular techniques and more particularly to an arrangement by which better control of delivery can be achieved. 
     BACKGROUND OF THE INVENTION 
     This invention will be generally discussed in relation to deployment of a stent graft where it is desirable to catheterize a side branch from a main vessel such as to catheterize an iliac artery from a contralateral iliac artery but it is to be understood that the invention is not so limited and may relate to any body lumen in which such a deployment is required. It may, for instance, be used for catheterization of one of the great vessels of the thoracic arch or the renal arteries. 
     Throughout this specification the term distal with respect to a portion of the aorta, a deployment device or a stent graft means the end of the aorta, deployment device or stent graft further away in the direction of blood flow away from the heart and the term proximal means the portion of the aorta, deployment device or end of the stent graft nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be understood. 
     Stent grafts are used for treatment of vasculature in the human or animal body to bypass a repair or defect in the vasculature. For instance, a stent graft may be used to span an aneurism which has occurred in or associated with the iliac artery. In many cases, however, such a damaged or defective portion of the vasculature may include a branch vessel such as an internal iliac artery. Bypassing such a branch vessel without providing blood flow into it can cause problems and hence it has been proposed to provide a side branch or fenestration on a stent graft which when deployed is positioned over the opening to the side vessel and then another stent graft can be deployed through the side branch or fenestration into the side vessel to provide a blood flow path to the side vessel from the stent graft. 
     There have been proposals, for instance, to deploy a branched stent graft into the common iliac artery via a femoral artery from a femoral incision using the Seldinger technique. Such a branched stent graft has a side arm which is placed to extend into or at least adjacent the internal iliac artery and then a leg extension can be placed through the side arm into the internal iliac artery, however, the use of such devices is very dependent upon favorable layout of the arteries and the ability to obtain access over the aortic bifurcation and in many cases, access is extremely difficult. 
     It has been proposed to use an indwelling auxiliary catheter positioned in the introducer. To do this it is necessary to snare a guide wire extended from the indwelling auxiliary catheter into or towards the contralateral iliac artery. Snaring can be a problem because of the nature of the prior art indwelling catheters. Prior art indwelling catheters have been constructed from a plastics material which cannot transfer rotational or longitudinal movement from one end to the other. In such a situation the position of the proximal end of the indwelling auxiliary catheter from which guide wire being snared is extended cannot be rotated or extended to direct the auxiliary guide wire in a selected direction and hence the guide wire can become entangled around the nose cone of the introducer or the guide wire of the introducer. This can be a particular problem in the thoracic arch because the great vessels extend off the thoracic arch at a range of angles and it is difficult to rotate the delivery device accurately so high up in the vasculature from the entry point in the groin (for instance). 
     This invention proposes an alternative method for enabling access for snaring of an indwelling auxiliary guide wire and a deployment device to enable such a method to be practiced. 
     It is the object of this invention therefore to provide an improved deployment device or at least to provide a physician with a useful alternative. 
     SUMMARY OF THE INVENTION 
     In one form therefore the invention comprises a stent graft delivery device comprising a handle at a distal end, a nose cone dilator at a proximal end, the nose cone dilator including a distal end, a guide wire catheter extending from the handle to and through the nose cone dilator at the proximal end, a pusher catheter extending from the handle towards the proximal end of the delivery device, a stent graft retained on the delivery device between the distal end of the nose cone dilator and the pusher catheter, the stent graft having a graft lumen therethrough and the guide wire catheter extending through the graft lumen, a pusher lumen through the pusher catheter, the guide wire catheter extending through the pusher lumen and able to move longitudinally and rotationally with respect to the pusher, an indwelling catheter extending from the handle through the pusher lumen and the stent graft lumen outside the guide wire catheter towards the nose cone dilator, the indwelling catheter comprising a distal end adjacent the handle and a proximal end adjacent the nose cone dilator, the indwelling catheter being formed from a material able to transmit rotational and longitudinal movement (advancement and withdrawal) from the distal end to the proximal end thereof. 
     Preferably the indwelling catheter is formed from a material which is both flexible and resilient but able to transmit the rotational and longitudinal movement (advancement and withdrawal) from the distal end to the proximal end thereof as discussed above. 
     The indwelling catheter can comprise a material selected from Nitinol™, a nickel titanium alloy, or stainless steel. The indwelling catheter can have a diameter of from 1.2185 mm to 1.2195 mm and a wall thickness of from 0.12275 mm to 0.12125 mm. 
     Preferably the indwelling catheter comprises a more flexible proximal tip, the proximal tip being pre-formed into a curved shape. 
     The more flexible proximal tip of the indwelling catheter can be formed from a biocompatible plastics material selected from polyurethane and PTFE. 
     The more flexible proximal tip when formed from polyurethane or PTFE can have a length of from 2 to 10 cm, a diameter of from 1.455 mm to 1.445 mm and a wall thickness of from 0.235 mm to 0.225 mm. 
     Alternatively the more flexible proximal tip can comprise the same material as the main part of the indwelling catheter and there may be a wall thickness transition between the more flexible proximal tip and the main part of the indwelling catheter to give the more flexible tip. The more flexible proximal tip can have a preformed curve heat set into it so that after it is released from the groove in the nose cone dilator sheath as discussed below it will regain its curved shape. 
     The Nitinol™ or stainless steel indwelling catheter can have a diameter for its entire length of from 1.2 mm to 1.3 mm and a wall thickness along a majority of its length of from 0.13 mm to 0.14 mm and in the tip portion a wall thickness of from 0.10 mm to 0.12 mm. 
     The nose cone dilator can comprise a longitudinal groove on its outer surface and the proximal end of the indwelling catheter can be received in the longitudinal groove. 
     There can be further included a sheath extending to the nose cone dilator and the sheath retaining the indwelling catheter in the longitudinal groove and retraction of the sheath allowing the proximal tip to regain its curved shape. 
     The distal end of the indwelling catheter can comprise a haemostatic seal. 
     In an alternative form the invention comprises a stent graft delivery device comprising a handle at a distal end, a nose cone dilator at a proximal end, the nose cone dilator including a distal end, a guide wire catheter extending from the handle to and through the nose cone dilator at the proximal end, a pusher catheter extending from the handle towards the proximal end of the delivery device, a stent graft retained on the delivery device between the distal end of the nose cone dilator and the pusher catheter, the stent graft having a graft lumen therethrough and the guide wire catheter extending through the graft lumen, a pusher lumen through the pusher catheter, the guide wire catheter extending through the pusher lumen and able to move longitudinally and rotationally with respect to the pusher, an indwelling catheter extending from the handle through the pusher lumen and the stent graft lumen outside the guide wire catheter towards the nose cone dilator, the indwelling catheter comprising a distal end adjacent the handle and a proximal end adjacent the nose cone dilator, the indwelling catheter comprising a main portion being a Nitinol hypotube and a proximal tip portion formed from a more flexible polyurethane tube, the proximal tip portion comprising a pre-formed curve whereby the indwelling catheter is able to transmit rotational and longitudinal movement (advancement and withdrawal) from the distal end to the proximal end thereof. 
     Preferably the nose cone dilator includes an outer surface and the nose cone dilator comprises a longitudinal groove on the outer surface and the flexible proximal end of the indwelling catheter is received in the longitudinal groove and thereby straightens out the pre-formed curve. 
     There may be further included a sheath extending to the nose cone dilator, wherein the sheath retains the indwelling catheter in the longitudinal groove during introduction of the delivery device and retraction of the sheath allows the proximal tip to regain its pre-curved shape. 
     It will be seen that by this invention an introducer device is provided in which the indwelling catheter can be controlled in its rotational position with respect to the delivery device so that a guide wire extending through the indwelling catheter can be snared from a side arm or a branch vessel from a main vessel and can then be catheterized. This is achieved by forming the indwelling catheter from a material which enables rotational forces to be transmitted along the full length of the indwelling catheter to its proximal end where a flexible tip can be rotated by action from outside the patient to direct the tip of the indwelling catheter towards the side vessel. The tip has preferably a pre-formed curve. Retraction or the sheath or advancement of the indwelling catheter from the sheath and rotation can enable accurate deployment of the indwelling guide wire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       This then generally describes the invention but to assist with understanding reference will now be made to the accompanying drawings which show a preferred embodiment of the invention. 
       In the drawings: 
         FIG. 1  shows an introducer device incorporating an auxiliary catheter according to one embodiment of the present invention; 
         FIG. 2  shows detail of the handle portion of the delivery device shown in  FIG. 1 ; 
         FIG. 3  shows detail of the connection between one portion of the indwelling catheter and its tip portion; 
         FIG. 4  shows detail of the proximal end of the indwelling catheter; 
         FIGS. 5 and 6  show various stages of deployment of the indwelling catheter at the proximal end of a stent graft delivery device; and 
         FIG. 7  shows an alternative embodiment of indwelling catheter according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Now looking more closely at the drawings it will be seen that the delivery device  10  includes a handle portion  12  and a portion  14  which is deployed into a patient during the endovascular procedure. The portion to be entered in the patient comprises a nose cone dilator  16  with a longitudinal groove  18  on its outer surface. A sheath  20  extends from a sheath hub  22  to the nose cone dilator  16 . As shown in  FIG. 1  the sheath  20  has been partially retracted by retraction of the hub  22  to show a curved tip  24  of an indwelling catheter  26 . The indwelling catheter  26  is formed partially from a Nitinol hypotube and extends from the curved tip  24  to a haemostatic seal  28  adjacent to the handle  12  of the delivery device  10 . The curved tip  24  is formed from a softer more flexible material which preferably will retain a set curvature as discussed below in relation to  FIG. 4 . The indwelling catheter extends through a hemostatic seal  40  in the handle and the lumen  31  of the pusher  30 . 
     The pusher  30  extends from the handle  12  through the hub  22  and terminates distally of the nose cone dilator  16 . A guide wire catheter  32  extends from a syringe hub  34  through a pin vice  36  at the rear of the handle  12  through the lumen  31  of the pusher  30  to the nose cone dilator  16 . 
     As can also be seen in detail in  FIGS. 3 and 4  the indwelling catheter  26  includes a more rigid portion of tube  26  which is flexible and resilient and can transfer rotational and longitudinal movement and a tip portion  24  connected at a connection  25 . In this embodiment the portion  26  is formed from Nitinol and the tip portion  24  is formed from polyurethane and preferably a radiopaque polyurethane so that the position of the curved tip  24  can be visualized. The connection  25  is shown as a push fit but can be any other convenient form of connection. The tip portion  24  has a pre-formed curve  24   a  which can be straightened out by being engaged under the sheath  20  but will resume its curved shape when released from the sheath  20 . When straightened out by the sheath  20  the curved portion  24   a  of the tip portion  24  is received in the longitudinal groove  18  (see  FIG. 1 ). 
     The main portion of the indwelling catheter of the present invention is flexible so that it can track through the vasculature of a patient along with the delivery device but sufficiently rigid such that it can transfer rotation or longitudinal pushing and pulling. The tip portion is flexible so that it can be straightened out to be received in the groove in the outer surface of the nose cone dilator but sufficiently rigid that it can be rotated to enable direction of the pre-formed curved tip as desired by a physician during an endovascular operation. Both portions are hollow so that an auxiliary guide wire can be deployed through them. 
     Along the length of the delivery device the auxiliary catheter  26  extends through a lumen  38  in the pusher  24  and in the handle extends through a haemostatic seal  40  and then extends out of the rear of the handle. An auxiliary guide wire  42  extends through the indwelling catheter  26  and can be manipulated to extend out of the proximal end of the auxiliary catheter. 
       FIGS. 5 and 6  show the proximal end of a delivery device according to one embodiment of the present invention. 
     In  FIG. 5  a cross-sectional view is shown of the proximal end of the introducer device. In this embodiment the sheath  20  is advanced to cover the stent graft  44  which is retained around the guide wire catheter  32  just distal of the nose cone dilator  16 . The more flexible tip portion  24  of the indwelling catheter  26  is received in the longitudinal groove  18  in the nose cone dilator  16  and the curved portion has been straightened out to lie flat in the groove  18 . The indwelling catheter  26  extends through the lumen of the stent graft  44 . 
     As shown in  FIG. 6  the sheath  20  has been retracted so that it still covers the stent graft  44  but has released the curved tip end  24   a  of the tip portion  24  of the indwelling catheter  26  so that it has regained its original curved shape. At this stage rotation of the indwelling catheter  26  by gripping and rotating the haemostatic seal  28  (see  FIG. 1 ) will transfer the rotation as indicated by arrow  26   a  along the length of the delivery device due to the more rigid nature of the Nitinol portion of the indwelling catheter and this will cause the tip to rotate, as shown by arrow  24   b , enabling the end of the indwelling catheter to more accurately aimed at a side vessel such that the indwelling guide wire  42  can be extended to catheterize the side vessel. Similarly the rigid nature of the Nitinol portion of the indwelling catheter enables longitudinal movement (advancement and withdrawal) of the indwelling catheter  26  as shown by the arrow  26   b . This enables fine positioning of the curved tip longitudinally in the vasculature of a patient without a physician having to move then entire delivery device. 
       FIG. 7  shows an alternative embodiment of indwelling catheter according to the present invention. In this embodiment the indwelling catheter  50  includes a more rigid portion of tube  52  which is flexible and resilient and can transfer rotational and longitudinal movement and a tip portion  54 . In this embodiment the entire indwelling catheter is formed from Nitinol™ or stainless steel. The tip portion  54  is formed with a lesser wall thickness produced by a wall thickness transition at  56 . The tip portion  54  has a pre-formed curve which can be straightened out by being engaged under the sheath  20  (see  FIG. 5 , for instance) but will resume its curved shape when released from the sheath  20 . When straightened out by the sheath  20  the curved portion  56  is received in the longitudinal groove  18  on the outer surface of the nose cone dilator (see  FIG. 5 ). 
     In this embodiment the indwelling catheter can have a diameter for its entire length of from 1.2 mm to 1.3 mm and a wall thickness along a majority of its length of from 0.13 mm to 0.14 mm and in the tip portion a wall thickness of from 0.10 mm to 0.12 mm. 
     Throughout this specification various indications have been given as to the scope of the invention but the invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration only and not for limitation.