as shown in the exemplary drawings wherein like reference numerals indicate like or corresponding elements among the figures , the present invention includes a bifurcated stent delivery system for treating bifurcated vessels in , for example , the coronary arteries , veins , arteries , and other vessels in the body . prior art attempts at implanting intravascular stents in a bifurcation have proved less than satisfactory . for example , fig1 - 4 depict prior art devices which include multiple stents being implanted in both the main vessel and a side branch vessel . in fig1 a prior art “ t ” stent is implanted such that a first stent is implanted in the side branch near the ostium of the bifurcation , and a second stent is implanted in the main vessel , across the side branch ostium . with this approach , portions of the side branch vessel are left uncovered , and blood flow to the side branch vessel must necessarily pass through the main vessel stent , causing possible obstructions or thrombosis . referring to fig2 three prior art stents are required to stent the bifurcation . in fig3 the prior art method includes implanting two stents side by side , such that one stent extends into the side branch vessel and the main vessel , and the second stent is implanted in the main vessel . this results in a double - barreled lumen which can present problems such as thrombosis , and turbulence in blood flow . referring to the fig4 prior art device , a first stent is implanted in the side branch vessel , a second stent is implanted in a proximal portion of the main vessel , and a third stent is implanted distal to the bifurcation , thereby leaving a small gap between the stents and an uncovered lumenal area . referring to fig5 a and 5b , a prior art stent is configured for deployment in side branch vessel 5 . in treating side branch vessel 5 , if a prior art stent is used , a condition as depicted will occur . that is , a stent deployed in side branch vessel 5 will leave a portion of the side branch vessel exposed , or as depicted in 5 b , a portion of the stent will extend into main vessel 6 . turning to fig6 - 12 , in one embodiment of the present invention , stent delivery assembly 10 is provided for treating bifurcated vessels . in this embodiment , a y - shaped stent is implanted to cover the bifurcation . catheter 12 can be configured as a dual balloon y - shaped catheter having a proximal end and a distal end . the catheter includes first expandable member 14 and second expandable member 16 that are configured to reside side - by - side ( y - shaped ) for low profile delivery and to spring apart for implanting y - shaped stent 18 . each of the expandable members has a proximal end and a distal end . the stent is removably mounted on the first and second expandable members . a first guide wire lumen 20 is provided for receiving first guide wire 22 . the first guide wire lumen extends through at least a portion of catheter 12 including first expandable member 14 . a second guide wire lumen 24 is provided for receiving second guide wire 26 . the second guide wire lumen extends through at least a portion of the catheter including second expandable member 16 . the expandable members can be inflatable non - distensible balloons . the guide wires 22 , 26 preferably are stiff wires each having a diameter of 0 . 014 inch , but can have different diameters and degrees of stiffness as required for a particular application . a particularly suitable guide wire can include those manufactured and sold under the tradenames sport ® and ironman ®, manufactured by advanced cardiovascular systems , incorporated , santa clara , calif . a tubular member , such as sheath 28 , is provided , wherein the first expandable member and the second expandable member are normally biased apart , but are restrained and held together by the sheath to provide a low profile during delivery of y - shaped stent 18 . the sheath can be formed from a polymer such as polyethylene , polyurethane , and nylons , although other similar polymeric material may also be suitable , such as polyetheretherketone ( peek ), polytetrafluoroethylene ( ptfe ), polyethylene terephthalate ( pet ), and the like . other suitable materials can be used as are known to those skilled in the art . the catheter 12 further includes an inflation lumen ( not shown ) for inflating first and second expandable members 14 , 16 simultaneously . the expandable members can be inflated by delivering a suitable inflation media , such as saline , to the expandable members via the inflation lumen . in one embodiment , the second expandable member is longer than the first expandable member so that distal portion 30 of the second expandable member protrudes from sheath 28 during delivery to facilitate tracking . in one method of stenting a bifurcated vessel , as shown in fig9 - 12 , y - shaped stent 18 is mounted on first and second expandable members 14 , 16 . the second guide wire 26 is positioned distal of the bifurcation in first vessel branch 6 . the second guide wire is then back loaded into second guide wire lumen 24 . the catheter 12 and sheath 28 are advanced over the second guide wire so that the catheter is advanced distally of the bifurcation in the first vessel branch . during the advancement of the catheter , the first and second expandable members are restrained and held together by sheath . consequently , the sheath helps to provide a low profile during delivery of the stent . in keeping with the invention , sheath 28 is withdrawn proximally until first expandable member 14 and second expandable member 16 are released and spring apart . the catheter 12 is then withdrawn proximally to a position proximal of the bifurcation . in one embodiment , first guide wire 22 has been contained as an integrated guide wire within first guide wire lumen 20 up to this point . alternatively , the first guide wire may be inserted into the proximal end of the first guide wire lumen at this time . the first guide wire is then advanced out of the first guide wire lumen and into second vessel branch 5 distally of the bifurcation . if , after withdrawal of the sheath to release the expandable members , the device is seen to be oriented such that first expandable member 14 is further away from vessel 5 than is second expandable member 16 , it may be desirable to withdraw second guide wire 26 and readvance it into vessel 5 with first guide wire 22 then advanced into vessel 6 . this reassignment of wires permits avoidance of rotation of more than 90 degrees . in situations in which there is concern about recrossing of the lumen of the side branch vessel with either wire , this wire reassignment is performed before catheter 12 is withdrawn proximal to the bifurcation . the y - shaped stent 18 is implanted by advancing distally over first and second guide wires 22 , 26 until the stent is positioned at the bifurcation in apposition with carina 32 . due to the appropriate wire selection , rotation of no more than 90 degrees will be required . the stent is implanted by inflating first and second expandable members 14 , 16 , which are designed to inflate simultaneously . then the first and second expandable members are deflated and the catheter and guide wires can be withdrawn from the patient &# 39 ; s vasculature . the novel arrangement of sheath 28 and guide wires 22 , 26 and their respective lumens permit single unit transport of a y - shaped stent to the distal target site without wire wrapping problems and it allows for minimal requirements of rotation of the device ( less than 90 degrees ) for optimal deployment ( allowing minimal twist deformity ). in a related method , y - shaped stent 18 is mounted on first and second expandable members 14 , 16 . the second guide wire 26 is positioned distal of the bifurcation in first vessel branch 6 . the second guide wire is then back loaded into second guide wire lumen 24 . the catheter 12 and sheath 28 are advanced over the second guide wire so that the catheter is advanced proximally of the bifurcation in the first vessel branch . during the advancement of the catheter , the first and second expandable members are restrained and held together by the sheath . consequently , the sheath helps to provide a low profile during delivery of the stent . in keeping with the invention , sheath 28 is withdrawn proximally until first expandable member 14 and second expandable member 16 are released and spring apart . in one embodiment , first guide wire 22 has been contained as an integrated guide wire within first guide wire lumen 20 up to this point . alternatively , the first guide wire may be inserted into the proximal end of the first guide wire lumen at this time . the first guide wire is then advanced out of the first guide wire lumen and into second vessel branch 5 distally of the bifurcation . next , catheter is advanced distally over first and second guide wires 22 , 26 until y - shaped stent 18 is positioned at the bifurcation in apposition with carina 32 . due to the appropriate wire selection , rotation of no more than 90 degrees will be required . the stent is implanted by inflating first and second expandable members 14 , 16 , which are designed to inflate simultaneously . then the first and second expandable members are deflated and the catheter and guide wires can be withdrawn from the patient &# 39 ; s vasculature . the novel arrangement of sheath 28 and guide wires 22 , 26 and their respective lumens permit single unit transport of a y - shaped stent to the distal target site without wire wrapping problems and it allows for minimal requirements of rotation of the device ( less than 90 degrees ) for optimal deployment ( allowing minimal twist deformity ). notably , it is contemplated that the methods of the present invention can be accomplished with any suitable catheter 12 . referring to fig1 and 14 , another embodiment of the dual balloon y - shaped catheter is depicted . the catheter has first stem 40 and second stem 42 . the first stem 40 is connected to first expandable member 14 . the second stem 42 is connected to second expandable member 16 having distal portion 30 for tracking . in this embodiment , the second expandable member is approximately twice as long as the first expandable member ; however , it is contemplated that the expandable members can be of varying lengths . the expandable members can be simultaneously inflated via an inflation lumen ( not shown ). the first guide wire 22 is positioned within the first expandable member and the second guide wire is positioned within the second expandable member . the first and second expandable members are normally biased apart , but are restrained and held together by sheath 28 to provide a low profile during delivery of y - shaped stent 18 . while the invention herein has been illustrated and described in terms of a catheter assembly and method of use , it will be apparent to those skilled in the art that the invention can be used in other instances . other modifications and improvements may be made without departing from the scope of the invention .
an improved catheter assembly and method are provided for treating bifurcated vessels . the catheter assembly of the present invention includes a tubular sheath for restraining dual balloons normally biased apart . withdrawal of the sheath allows the balloons to separate and deploy intravascular stents in a bifurcated vessel . the catheter assembly also includes the feature of containing two guide wire lumens in a single catheter designed to track over a single wire prior to arrival at the bifurcation , thus preventing wire wrapping and crossing of the wires .