a system of renal , abdominal , and iliac arteries is denoted in fig1 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 . fig2 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 ; fig2 is a post deployment depiction . 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 fig2 , guide wire 24 and introducer sheath 26 are in position for advancing a novel main catheter , not depicted in fig2 . as depicted in fig3 , 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 . reference numeral 32 at the lower left corner of fig3 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 fig1 b . inner cannula 32 is formed by two cannulas that are secured to one another at their respective distal ends . 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 . 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 . 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 . the lower left corner of fig4 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 fig4 ) 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 fig1 a . 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 . 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 fig4 . 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 . fig5 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 . 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 fig6 . the guide wire referred to but not depicted in connection with fig5 is depicted in the lower right corner of fig6 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 . 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 . 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 fig7 . magnetic tips 40 and 44 are then separated from one another . fig8 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 . fig9 depicts contralateral guide wire 46 in its fig8 position , i . e ., with mating catheter 42 removed . inner cannula 32 , depicted in the lower left corner of fig1 , 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 . fig1 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 . fig1 depicts site 10 when main catheter 30 is fully withdrawn through puncture opening 18 a . guide wires 24 and 46 remain in their respective fig1 positions . contralateral guide wire 46 is used to advance the contralateral limb of the stent graft for accurate placement . fig1 a 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 . radiopaque ring 58 is also depicted in said fig1 a , 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 . fig1 a 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 fig1 . fig1 b 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 . fig1 a 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 . in both embodiments of inner cannula 32 , the first cannula having lumen 32 a receives main guide wire 24 as best depicted in fig1 and the second cannula having lumen 32 b is cut near its distal end to form extended arm 36 , as also best depicted in fig1 . 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 . fig1 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 . extended arm 36 and hence magnetic tip 40 have exited exit opening 31 in fig1 because inner cannula 32 has been pulled in the distal - to - proximal direction indicated by directional arrow 34 as disclosed above in connection with fig4 . the function of kick plate 62 in controlling the angle of extended arm 36 is made clear by said fig1 . in a third embodiment of extended arm 36 , depicted in fig1 , 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 . in an additional embodiment of the inventive structure as a whole , also depicted in fig1 , 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 . in still another embodiment of the novel structure as a whole , also depicted in fig1 , 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 . 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 fig1 . 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 . 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 .
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 .