Abstract:
A method for installing a stent graft in therapeutic relation to an abdominal artery aneurysm includes the steps of advancing the stent graft over a guide wire and an introducer sheath, followed by advancing a main catheter over the guide wire and the introducer sheath. An inner catheter in the lumen of the main catheter is pulled to cause a magnet-carrying extended arm to encounter a kick plate in the main catheter lumen and to exit that lumen through an exit opening formed in the main catheter. A mating catheter having a magnetic tip is advanced over a contralateral guide wire and manipulated until the respective magnets engage. After specific positioning of the contralateral guide wire, the magnets are decoupled, the mating catheter is retracted, the inner catheter is pushed to return the extended arm into the main catheter lumen through the exit opening and the main catheter is withdrawn.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to surgical tools and methods. More specifically, it relates to a tool and method for installing a stent graft in an abdominal artery to prevent rupturing of the artery due to an aneurysm. 
         [0003]    2. Brief Description of the Related Art 
         [0004]    When stents for the abdominal artery were first introduced, the patient&#39;s torso was opened in a major operation, known as abdominal aortic aneurysm (AAA) repair. The abdominal artery lies in front of the spine but behind the major organs, several of which had to be moved out of the way so that the stent graft could be installed. Accordingly, AAA surgery could last six to eight hours, and was followed by a long and painful recovery period. 
         [0005]    Modern stent grafts, however, are introduced into the abdominal artery through a small incision made in each of the common iliac arteries, thereby avoiding the complications often associated with AAA and greatly reducing the time required to complete the operation, post-operative pain and recovery time. 
         [0006]    Since the patient&#39;s torso is not opened, the stent graft and the tool or tools used to position it in the desired position must be viewed through suitable imaging means. 
         [0007]    The placement of guide wires and catheters needed to control stent graft placement can be difficult. In a worst-case scenario, the placement procedure may not work and the surgeon must resort to conventional AAA. 
         [0008]    Thus there is a need for an improved tool and method for installing a stent graft in therapeutic relation to a diseased section of an abdominal artery. The improved tool and method would simplify stent graft placement and reduce the number of times that minimally invasive surgery must be abandoned in favor of prior art surgery. 
         [0009]    However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how such an improved tool and method could be provided. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The long-standing but heretofore unfulfilled need for an improved tool for installing a stent graft in a diseased artery and a method for its use is now met by a new, useful, and nonobvious invention. 
         [0011]    The novel structure has utility in facilitating the installation of a stent graft having an elongate limb and a truncate limb in an abdominal artery for treatment of an abdominal aortic aneurysm. 
         [0012]    The novel method includes the now conventional step of advancing a main body of the stent graft over a main body guide wire and a first introducer sheath to deliver and deploy the main body where needed without blocking the renal arteries. This insertion is made through a first common iliac artery. 
         [0013]    The term “proximal” as used hereinafter is defined as the end of the guide wire, catheter, cannula, or other mechanical structure that is nearest to the surgeon. The term “distal” will therefore refer to the end furthest from the surgeon. The alternative definition where “proximal” refers to nearest the heart and “distal” refers to furthest from the heart is not used. 
         [0014]    The novel structure includes a main catheter having a non-round lumen that houses an inner cannula. The inner cannula is slideably received within the non-round lumen of the main catheter and can be pushed by a surgeon in a proximal-to-distal direction or pulled by the surgeon in a distal-to-proximal direction. 
         [0015]    The inner cannula is defined as a first cannula that slideably receives a main guide wire and a second cannula that includes an extended arm. However, in a second embodiment, the extended arm is the only part of the second cannula. 
         [0016]    The lumen is oval or some other suitable non-round shape to prevent relative rotation between the inner cannula and the main catheter. Accordingly, rotation of the main catheter about its longitudinal axis of symmetry effects simultaneous and corresponding rotation of the inner cannula. 
         [0017]    The inner cannula is non-round because it is formed by first and second parallel cannulas that are secured to one another at their respective distal ends. A first cannula is dedicated to slideably receiving a main guide wire as aforesaid and a second cannula provides an extended arm that, like the main guide wire, has utility in placement of the stent graft. In end view or transverse section the first and second cannulas produce a figure eight profile. 
         [0018]    The first and second cannulas are provided in two (2) embodiments but they are interconnected to one another at their respective distal ends in both embodiments. 
         [0019]    In the first embodiment, the first and second cannulas are secured to one another at their respective distal ends and also along their respective lengths. The second cannula is cut a few inches from its distal end and is separated from the first cannula from the cut to the point where its distal end is connected to the distal end of the first cannula. 
         [0020]    In the second embodiment, the first and second inner cannulas are not secured to one another along their respective lengths proximal to the interconnected distal ends. 
         [0021]    In the second embodiment, an extended arm is formed by cutting the second cannula a few inches proximal to its distal end and discarding the extent of said second cannula that is proximal to the cut. The distal end of the extended arm is thus secured to the distal end of the first cannula, it being understood that the extended arm is the preserved, not discarded length of the second cannula. 
         [0022]    In both embodiments of the inner cannula, an exit opening is formed in the main catheter so that the free end of the extended arm exits and re-enters the exit opening as the steps of the novel method are followed. In a first embodiment of the extended arm, the free end or tip of the extended arm has a ferromagnetic material, i.e., a metallic wire extending from said extended arm for a short distance. In a second embodiment of the extended arm, a magnet supplants the wire. 
         [0023]    The operator advances and rotates the main catheter so that the exit opening and the extended arm are positioned in alignment with the gate of the stent graft, said gate being positioned in the truncate limb just below the flow divider of the stent graft as is well-known. 
         [0024]    The main catheter is then advanced over the main body guide wire and the first introducer sheath until a leading end of the main catheter is positioned distal to the distal end of the stent graft. The operator then manually pulls the inner cannula in a distal-to-proximal direction, i.e., the inner cannula is retracted relative to the main catheter to allow the extended arm of the inner cannula to advance out of the main catheter exit opening. A kick plate is provided as a part of the main catheter for that purpose, i.e., the extended arm encounters the kick plate as the inner cannula is retracted and said kick plate directs the free end of the extended arm to exit the main catheter through the exit opening. 
         [0025]    The main catheter is then manipulated until the free end of the extended arm is external to the truncate limb of the stent graft, i.e., until the free end of the extended arm has passed through the gate of the stent graft and exited the truncate limb. 
         [0026]    A mating catheter has an exit opening formed in it as well and has a magnetic tip secured to its distal end. The mating catheter is advanced over a contralateral guide wire introduced through the second common iliac artery and a second introducer sheath smaller in diameter than the first introducer sheath is introduced through said second common iliac artery. 
         [0027]    In the first embodiment of the extended arm, the operator advances the mating catheter and manipulates it until the magnetic tip of the mating catheter magnetically couples with the ferromagnetic material at the tip of the extended arm. In the second embodiment of the extended arm, the operator advances the mating catheter and manipulates it until the magnetic tip of the mating catheter magnetically couples with the magnetic tip of the extended arm, said magnetic tips being of opposite polarity. 
         [0028]    The main catheter and the mating catheter are then advanced together in a proximal-to-distal direction through the gate in order to advance the contralateral guide wire through an exit opening formed in the mating catheter. The contralateral guide wire is advanced until it is distal of the distal end of the stent graft as is the main guide wire. The gate is thus said to be cannulated. 
         [0029]    The magnetically engaged tips are then decoupled from one another by holding the main catheter in a fixed position while pulling on the mating catheter. 
         [0030]    The mating catheter is then retracted through a contralateral puncture site, leaving the contralateral guide wire in place. 
         [0031]    The inner cannula is then pushed in a proximal-to-distal direction to retrieve the extended arm into the main catheter through the exit opening formed in the main catheter. The main catheter is then withdrawn in a distal-to-proximal direction through the puncture opening formed in the ipsilateral side of the patient&#39;s body, leaving the main catheter guide wire and the contralateral guide wire in place. 
         [0032]    The contralateral wire is then used to advance the contralateral stent graft limb until it is accurately placed. 
         [0033]    The novel structure further includes a radiopaque ring that is positioned in the lumen of the main catheter. The radiopaque ring has an opening formed therein that is in registration with the exit opening formed in the main catheter. The radiopaque ring enhances the imaging of the main catheter exit opening location and structurally reinforces the main catheter in the region of the main catheter exit opening. 
         [0034]    The radiopaque ring further includes a kick plate that controls an angle of exit of the extended arm from the main catheter. 
         [0035]    An important object of the invention is to simplify the procedure required to install a stent graft in a diseased abdominal artery; 
         [0036]    A closely related object is to facilitate gate cannulation, i.e., to facilitate the introduction of a contralateral guide wire into the gate of the stent graft; 
         [0037]    A broad object is to provide improved tools that enable the procedures of stent graft introduction and placement to be simplified; and 
         [0038]    Another object is to provide a means for magnetically coupling together the free end of an extended arm that forms a part of an inner cannula and the free end of a mating catheter. 
         [0039]    These and other important objects, advantages, and features of the invention will become clear as this disclosure proceeds. 
         [0040]    The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the disclosure set forth hereinafter and the scope of the invention will be indicated in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0041]    For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
           [0042]      FIG. 1  is a diagrammatic representation of the renal, abdominal, femoral and iliac arteries where the abdominal and iliac arteries are diseased; 
           [0043]      FIG. 2  is the first animation in a series of eleven (11) animations depicting how the abdominal aneurysm of  FIG. 1  is treated with a stent graft; 
           [0044]      FIG. 3  is the second animation of said series of animations; 
           [0045]      FIG. 4  is the third animation of said series of animations; 
           [0046]      FIG. 5  is the fourth animation of said series of animations; 
           [0047]      FIG. 6  is the fifth animation of said series of animations; 
           [0048]      FIG. 7  is the sixth animation of said series of animations; 
           [0049]      FIG. 8  is the seventh animation of said series of animations; 
           [0050]      FIG. 9  is the eighth animation of said series of animations; 
           [0051]      FIG. 10  is the ninth animation of said series of animations; 
           [0052]      FIG. 11  is the tenth animation of said series of animations; 
           [0053]      FIG. 12  is the eleventh and final animation of said series of animations; 
           [0054]      FIG. 13A  is a longitudinal sectional view of the main catheter of this invention; 
           [0055]      FIG. 13B  is an end view of the structure depicted in  FIG. 13A ; 
           [0056]      FIG. 14A  is a longitudinal sectional view of the inner tubing of this invention; 
           [0057]      FIG. 14B  is an end view of the structure depicted in  FIG. 14A ; 
           [0058]      FIG. 15  is a longitudinal sectional view depicting the inner tubing and the extended arm in the lumen of the main catheter; 
           [0059]      FIG. 16  is a longitudinal sectional view of the structure depicted in  FIG. 15  but with the extended arm extending through the exit hole formed in the main catheter; and 
           [0060]      FIG. 17  is a perspective view of an additional embodiment of the main catheter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0061]    A system of renal, abdominal, and iliac arteries is denoted in  FIG. 1  as a whole by the reference numeral  10 . Healthy renal arteries are denoted  12 ,  14 , an abdominal artery having a diseased section  16   a  where an aneurysm has formed is denoted  16 , a first common iliac artery having a diseased section  18   b  where an aneurysm has formed is denoted  18 , and a second, healthy common iliac artery is denoted  20 .  18   a  indicates where first common iliac artery  18  is cut down for insertion of guide wires, insertion sheaths, and catheters, and  20   a  indicates where second common iliac artery  20  is cut down for the same reason. 
         [0062]      FIG. 2  depicts arterial system  10  when the main body of stent graft  22  is advanced over guide wire  24  and introducer sheath  26 . The delivery system used to deliver and deploy the main body of a stent graft is not depicted;  FIG. 2  is a post deployment depiction. 
         [0063]    Stent graft  22  has elongate limb  22   a  and truncate limb  22   b  and is deployed so that it does not interfere with renal arteries  12 ,  14 . Wires  28  are known in the industry as the bare stent because no graft covers the bare wires. Wires  28  have no significant effect on blood flow through said renal arteries. In  FIG. 2 , guide wire  24  and introducer sheath  26  are in position for advancing a novel main catheter, not depicted in  FIG. 2 . 
         [0064]    As depicted in  FIG. 3 , novel main catheter  30 , having exit opening  31  formed therein, is then advanced over guide wire  24  and introducer sheath  26  until leading or distal end  30   a  of said main catheter is positioned beyond the distal end of stent graft  22 . Distal end  30   a  is clearly visible under fluoroscopic imaging. 
         [0065]    Reference numeral  32  at the lower left corner of  FIG. 3  indicates the inner cannula that is slideably mounted within the non-round lumen of main catheter  30 . The lumen of the main catheter may be round, like the external surface of the main catheter, if the inner cannula extends through a non-round structure that is added to the round lumen. One example of a non-round lumen is denoted  29  in  FIG. 13B . 
         [0066]    Inner cannula  32  is formed by two cannulas that are secured to one another at their respective distal ends. 
         [0067]    In a first embodiment of the inner cannula, the two cannulas are secured to one another along their respective lengths, thereby forming a figure eight configuration in transverse section or end view. The second cannula is cut a few inches from its distal end and separated from the first cannula along those few inches except at its distal end which is joined to the distal end of the first cannula. 
         [0068]    In a second embodiment of the inner cannula, the two cannulas are not secured to one another along their respective lengths proximal to the interconnected distal ends. In this second embodiment, the second cannula is cut a few inches from its distal end and the extent of the cannula proximal to the cut is discarded. The remaining extent of the second cannula forms the extended arm. 
         [0069]    The two cannulas that collectively form the inner cannula are joined to one another at their respective distal ends in both embodiments. First cannula  32   a  of said two cannulas slideably receives guide wire  24  and second cannula  32   b  forms extended arm  36 . Extended arm  36  is held against first inner cannula  32   a  by main catheter  30  when extended arm  36  is disposed within the lumen of main cannula  30 . 
         [0070]    The lower left corner of  FIG. 4  depicts manually pulling inner cannula  32  in the distal-to-proximal direction indicated by directional arrow  34  when the first or second embodiment of inner cannula  32  is used, i.e., both embodiments include extended arm  36 . Retraction of inner cannula  32  relative to stationary main catheter  30  therefore enables extended arm  36  (center of  FIG. 4 ) to travel through exit opening  31  formed in main catheter  30 . Exit opening  31  and its associated kick plate  62  that guides extended arm  36  out said exit opening is best depicted in  FIG. 13A . 
         [0071]    Main catheter  30  is then advanced and rotated so that exit opening  31  and therefore extended arm  36  are aligned with but spaced apart from the gate of the stent graft. As is well-known, the gate is located in truncate leg  22   b  slightly below the flow divider of the stent graft. 
         [0072]    When it is clear that extended arm  36  will pass through the gate and enter into the lumen of truncate leg  22   b  when inner catheter  32  is retracted relative to stationary main catheter  30 , i.e., pulled in a distal-to-proximal direction, inner catheter  32  is retracted until the distal end of extended arm  36  is external to truncate limb  22   b  of main stent graft  22  as depicted in  FIG. 4 . In a first embodiment of extended arm  36 , the free end of extended arm  36  is formed of a ferromagnetic material such as a wire and in a second embodiment, a magnetic tip is secured to said free end when main catheter  30  is manufactured. 
         [0073]      FIG. 5  depicts the next step of the novel method. Mating catheter  42  is advanced over a guide wire, not depicted, through surgical incision  20   a  in common iliac artery  20 . An introducer sheath, not depicted, smaller in diameter than introducer sheath  26 , is also introduced through said incision  20   a.  The leading end of mating catheter  42  carries magnetic tip  44  which has a magnetic polarity opposite to the magnetic polarity of magnetic tip  40  if the second embodiment of the extended arm is in use. 
         [0074]    Mating catheter  42  is then advanced and manipulated until magnetic tip  44  magnetically couples with magnetic tip  40  (or the ferromagnetic wire if the first embodiment of extended arm  36  is used) as illustrated in  FIG. 6 . 
         [0075]    The guide wire referred to but not depicted in connection with  FIG. 5  is depicted in the lower right corner of  FIG. 6  and is denoted  46 . It is hereinafter referred to as the contralateral guide wire. Reference numeral  48  denotes an exit opening formed in mating catheter  42  near its distal end for said contralateral guide wire  46 . 
         [0076]    Both catheters, i.e., main catheter  30  and mating catheter  42 , are advanced together in order to advance contralateral guide wire  46  through exit opening  48  in a proximal-to-distal direction. 
         [0077]    After contralateral guide wire  46  is successfully extended through exit opening  48 , it is extended until it is positioned distal to the distal end of the stent graft, just like the distal end of first guide wire  24 , as indicated in said  FIG. 7 . 
         [0078]    Magnetic tips  40  and  44  are then separated from one another. 
         [0079]      FIG. 8  depicts the respective positions of the parts after magnetic tips  40  and  44  are decoupled. The separation is accomplished by holding main catheter  30  in a fixed position while pulling on mating catheter  42 . Mating catheter  42  is then retracted through contralateral puncture site  20   a.  Contralateral guide wire  46  is left in place. 
         [0080]      FIG. 9  depicts contralateral guide wire  46  in its FIG. 8 position, i.e., with mating catheter  42  removed. 
         [0081]    Inner cannula  32 , depicted in the lower left corner of  FIG. 10 , is then pushed in the proximal-to-distal direction of directional arrow  52  to retrieve extended arm  36  through exit opening  31  into main catheter  30 . 
         [0082]      FIG. 11  depicts withdrawal of main catheter  30  and inner cannula  32 , including extended arm  36 , through puncture opening  18   a  in the ipsilateral side of the patient&#39;s body. 
         [0083]      FIG. 12  depicts site  10  when main catheter  30  is fully withdrawn through puncture opening  18   a.  Guide wires  24  and  46  remain in their respective  FIG. 11  positions. Contralateral guide wire  46  is used to advance the contralateral limb of the stent graft for accurate placement. 
         [0084]      FIG. 13A  is a longitudinal sectional view of main catheter  30 . Exit opening  31  is formed in main catheter  30 , said opening being the exit opening for extended arm  36 . 
         [0085]    Radiopaque ring  58  is also depicted in said  FIG. 13A , said radiopaque ring being disposed in lumen  29  of main catheter  30  and having opening  60  that is in registration with exit opening  31 . In addition to enhancing the imaging of the novel tool and procedure, radiopaque ring  58  also structurally reinforces main catheter  30  in the region of exit opening  31 . 
         [0086]      FIG. 13A  also depicts kick plate  62  which is formed in ring  58  and has utility in controlling the angle of exit of extended arm  36  as disclosed more fully in connection with  FIG. 16 . 
         [0087]      FIG. 13B  is an end view of main catheter  30 . Main catheter  30  has oval lumen  29  to receive inner cannula  32  and to prevent rotation of said inner cannula in said lumen of main catheter  30 . 
         [0088]      FIG. 14A  is a longitudinal sectional view of inner cannula  32 . Inner cannula  32  may be provided in two embodiments as aforesaid, both embodiments having a non-round structure that is prevented from rotation by the mating non-round lumen of main catheter  30 . 
         [0089]    In both embodiments of inner cannula  32 , the first cannula having lumen  32   a  receives main guide wire  24  as best depicted in  FIG. 15  and the second cannula having lumen  32   b  is cut near its distal end to form extended arm  36 , as also best depicted in  FIG. 15 . In the second embodiment of inner cannula  32 , that part of lumen  32   b  proximal to the cut is removed and discarded as aforesaid. In both embodiments, the first and second inner cannulas are separated from one another for a predetermined extent on the distal end of the cut, remaining connected to one another at their respective distal ends so that extended arm  36  has a free end that extends through exit opening  31  when inner cannula  32  is retracted in a distal-to-proximal direction. 
         [0090]      FIG. 15  is a longitudinal sectional view depicting extended arm  36  inside lumen  32   b  of inner cannula  32 . Magnetic tip  40  is in open communication with exit opening  31 . 
         [0091]    Extended arm  36  and hence magnetic tip  40  have exited exit opening  31  in  FIG. 16  because inner cannula  32  has been pulled in the distal-to-proximal direction indicated by directional arrow  34  as disclosed above in connection with  FIG. 4 . The function of kick plate  62  in controlling the angle of extended arm  36  is made clear by said  FIG. 16 . 
         [0092]    In a third embodiment of extended arm  36 , depicted in  FIG. 17 , said extended arm is formed of a nickel-titanium alloy (Nitinol® memory metal) so that its deployed shape can be predetermined at the time of manufacture. 
         [0093]    In an additional embodiment of the inventive structure as a whole, also depicted in  FIG. 17 , stainless steel tubing  33  ensleeves first inner cannula having lumen  32   a  along a predetermined extent thereof. Stainless steel tubing  33  is positioned in the lumen of main catheter  30  in non-sliding relation thereto. The stainless steel tubing facilitates pushing of the first inner cannula in a proximal-to-distal direction by providing rigidity in the direction of the pushing force. It also facilitates rotation of said first inner cannula and hence of the second inner cannula to which it is connected. However, stainless steel tubing  33  has limited flexibility. 
         [0094]    In still another embodiment of the novel structure as a whole, also depicted in  FIG. 17 , elongate coiled spring  35  ensleeves the first inner cannula along a predetermined extent thereof, said elongate coiled spring being positioned in lumen  29  of main cannula  30 . Coiled spring  35  facilitates pushing of the first inner cannula in a proximal-to-distal direction by providing rigidity in the direction of the pushing force and flexibility to negotiate bends or curves within the patient&#39;s body. It also facilitates rotation of main catheter  30  and hence of the first and second inner cannulas. 
         [0095]    Instead of providing main catheter  30  with an oval or other non-round lumen, a truncate non-rotation catheter  37  may be secured to lumen  29  of main catheter  30  as depicted in  FIG. 17 . Truncate catheter  37  is cut out or slotted as depicted to receive inner cannula  32  to prevent rotation of said inner cannula relative to said main catheter lumen as said inner cannula is slidingly advanced or retracted within the lumen of the main catheter as the novel method steps are performed. 
         [0096]    The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.