the present invention , which relates to stent assemblies configured for assembling in bifurcating vessels , is herein described , by way of example only , with reference to the accompanying drawings . the principles and operation of the present invention may be better understood with reference to the drawings and accompanying descriptions . before explaining at least one embodiment of the invention in detail , it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings . the invention is capable of other embodiments or of being practiced or carried out in various ways . also , it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting . in fig1 a , arteries 127 form an upper branch vessel lumen 151 , a proximal parent vessel lumen 129 and a distal parent vessel lumen 125 . fig1 b - 1 d show the crush method , noted above , for treating a bifurcation . as seen in fig1 b , a crush stent assembly 100 comprises a branch stent 206 configured for expansion in upper branch lumen 151 . branch stent 206 , shown herein without a jacket , comprises a metal or polymer tubular structure having mesh - like , apertures 270 . branch stent 206 is shown encircling a balloon 260 and , upon expansion of balloon 260 , branch stent 206 expands radially outward . as seen in fig1 c , branch stent 206 has expanded radially in upper branch lumen 151 so that branch stent 206 presses against a stenotic area of tissue 240 , thereby compressing and cracking stenotic area 240 radially outward within upper branch lumen 151 . to further ensure flow of blood , a second balloon ( not shown ) is expanded against a flange 102 to crush flange 102 into proximal lumen 129 and into distal lumen 125 . deployed stent assembly 100 crushes stenotic tissue 240 in lumens 151 , 129 and 125 , thereby allowing better circulation through arteries 127 . however , as noted above and seen in fig1 d , branch stent 206 creates a significant amount of metal related to flange 102 that may subject artery walls 127 to restenosis , in addition to causing turbulence and thrombosis formation . referring to fig2 a , in an embodiment of the present invention , a stent system 200 , comprises a proximal parent vessel stent 202 and a distal parent vessel stent 208 that are covered by an external jacket 204 . assembly 200 is positioned in artery 127 so that proximal stent 202 is positioned in proximal lumen 129 and distal stent 208 is positioned in distal lumen 125 . in embodiments , for example for use in a coronary vessel , proximal stent 202 is positioned between at least one millimeter and not more than about 20 millimeters from distal stent 208 . in other embodiments , proximal stent 202 is positioned about three millimeters from distal stent 208 . optionally , proximal stent 202 and distal stent 208 are placed in positions that stretches external jacket 204 therebetween . in alternative embodiments proximal stent 202 and distal stent 208 are configured and appropriately sized as cardiovascular stents , peripheral stents , abdominal aortic aneurysm stents , cerebral stents , carotid stents , endovascular stents , aortic valve stents , and pulmonary valve stents . as seen in fig2 b , balloon 260 has been inflated , thereby expanding stents 202 and 208 so that stent jacket 204 spans upper branch lumen 151 . optionally , balloon 260 is inflated in a manner that crushes stent jacket 204 to aid in opening in lumens 151 , 129 and 125 and to avoid jailing of upper branch lumen 151 by stent jacket 204 . as seen in fig2 c , balloon 260 has been removed and the structure of stent jacket 204 can be appreciated . stent jacket 204 typically comprises a knitted material having large apertures 103 . as seen in fig2 d , branch stent 206 positioned on balloon 260 has been pressed into stent jacket 204 , through one of apertures 103 . as seen in fig2 e , branch stent 206 has been expanded , thereby expanding aperture 103 and causing an encircling portion of jacket 231 to encircle branch stent 206 . in addition to the support provided by stents 202 , 206 and 208 , stent jacket 204 spanning therebetween , supports stenotic tissue 240 at the bifurcation of upper branch lumen 151 . using stent jacket 204 as a support along the bifurcation of upper branch lumen 151 results in low bifurcation - related bulk that could cause restenosis and / or thrombosis noted above . in alternative embodiments , balloon 260 ( fig2 d ) is first used alone to predilate one of apertures 103 , after which unexpanded branch stent 206 is pressed through predilated aperture 103 and expanded in upper branch lumen 151 . in embodiments , stents 202 , 206 and 208 comprise any metallic base including , inter alia : stainless steel , nitinol , tantalum , mp35n alloy , a cobalt - based alloy , a cobalt - chromium alloy , platinum , titanium , or other biocompatible metal alloys . in further embodiments , stents 202 , 206 and 208 are deployed in any vessel comprising , inter alia : cardiovascular tissue , peripheral tissue , an abdominal aortic aneurysm , cerebral tissue , carotid tissue , endovascular tissue , aortic valves , and / or pulmonary tissue . in still further embodiments , stent jacket 204 comprises any material manufactured by a process including , inter alia : interlacing knitting , interlocked knitting , braiding , interlacing , and / or dipping a porous mold into one or more reagents . as used herein , any reference to a “ knitted material ” includes any material that is manufactured by a knitting process , including , inter alia : a material knitted from a single fiber , similar to the process used in pantyhose nylon ; a double fiber knit , referred to as a “ double knit material ”; and includes fibers , either mono filament or multi filament fiber of , inter alia : polyethylene , polyvinyl chloride , polyurethane , nylon , a biocompatible polymer fiber , and stainless steal nitinol , or any other metal . in embodiments , proximal stent 202 , distal stent 208 and branch stent 206 comprise a metallic base from the group consisting of : stainless steel , nitinol , tantalum , mp35n alloy , a cobalt - based alloy , a cobalt - chromium alloy , platinum , titanium , or other biocompatible metal alloys . in embodiments , proximal stent 202 , distal stent 208 and branch stent 206 are manufactured with sufficient diameters to press at least a portion of the inner walls of artery 127 with a pressure of at least one atmosphere and no more than about 50 atmospheres . in embodiments , proximal stent 202 , distal stent 208 and branch stent 206 are manufactured with sufficient diameters to press at least a portion of the inner walls of artery 127 with a pressure of about 15 atmospheres . fig3 a shows a stent system 300 in which proximal stent 202 has been deployed in proximal lumen 129 , and branch stent 206 has been deployed in upper branch lumen 151 , while stent jacket 204 spans across distal lumen 125 . typically , upper branch lumen 151 has a smaller diameter than proximal lumen 129 and first balloon ( not shown ) having a smaller expanded diameter is used to expand branch stent 206 . as seen in fig3 b , following expansion of stent 206 , a second balloon 260 having a large expanded diameter is used to expand proximal lumen stent 202 . as seen in fig3 b , distal parent vessel stent 208 is pushed through apertures 103 . as seen in fig3 c and distal parent vessel stent 208 has been expanded in distal lumen 125 . referring to fig4 a , arteries 127 include a lower side branch lumen 152 . as seen in fig4 b , a dual branch stent assembly 400 comprises stent jacket 204 having an upper sleeve 406 that is partially inside - out and surrounding upper branch stent 206 . stent jacket 204 further comprises a lower sleeve 412 that is inside out and surrounding a lower branch stent 212 . dual branch stent assembly 400 has been positioned so that distal stent 208 , upon expansion with a balloon ( not shown ), opens distal lumen 125 . proximal stent 202 is then expanded with balloon 260 to open proximal lumen 129 . as seen in fig4 c , balloon 260 has been positioned inside lower branch stent 212 and during expansion , balloon 260 is used to push lower branch stent 212 into lower branch lumen 152 , thereby straightening lower jacket 204 so that sleeve 412 is no longer inside - out . balloon 260 then expands lower branch stent 212 to open lower branch lumen 152 . as seen in fig4 d , balloon 260 has been positioned inside upper branch stent 206 and , during expansion , balloon 260 is used to push upper branch stent 206 into upper branch lumen 151 , thereby straightening upper branch sleeve 406 . balloon 260 then expands upper branch stent 206 to open upper branch lumen 151 . as seen in fig4 e , an encircling portion 271 of lower branch sleeve 412 , partially covers lower branch stent 212 while an encircling portion 281 of upper branch sleeve 406 partially covers upper branch stent 206 , thereby providing support of stenotic tissue 240 therebetween . referring to fig5 a , a stent assembly 500 has been positioned and expanded so that proximal stent 202 is positioned in proximal lumen 129 and distal stent 208 is positioned in distal lumen 125 . stent jacket 204 , positioned between stents 202 and 208 , includes a stretchable material 510 . as seen in fig5 b , balloon 260 , surrounded by unexpanded upper branch stent 206 has been pressed into stretchable material 510 , causing stent jacket 204 to bulge into upper branch lumen 151 . in fig5 c , balloon 260 has been expanded , thereby causing a partial expansion of upper branch stent 206 . partially expanded upper branch stent 206 stretches stretchable material 510 , creating considerable tension on the portion of stent jacket 204 that spans upper branch lumen 151 . in fig5 d , balloon 260 has been partially deflated and pressed in an upward direction 512 , thereby puncturing material 510 and creating an opening 518 . partially deflated balloon 260 is then moved in a downward direction 514 and partially inflated to expand and be secured within upper branch stent 206 . balloon 260 and upper branch stent 206 are then moved in upward direction 514 causing upper branch stent 206 to pass through opening 518 and into upper branch lumen 151 . balloon 260 is then fully expanded to cause upper branch stent 206 to fully expand . as seen in fig5 e , upper branch stent 206 is partially covered by stretchable material 510 , fully expanded in upper branch lumen 151 while balloon 260 has been deflated and is being moved in direction 514 to be removed percutaneously from artery 127 . referring to fig6 a , a stretch stent assembly 600 has been positioned and expanded so that proximal stent 202 is positioned in proximal lumen 129 and distal stent 208 is positioned in distal lumen 125 . as seen in fig6 b , balloon 260 , has been pressed into stretchable material 510 , causing stent jacket 204 to bulge into upper branch lumen 151 . in fig6 c , balloon 260 has been fully expanded , thereby puncturing material 510 and creating opening 518 . in fig6 d , balloon 260 has been partially deflated and pulled downward in direction 514 . following loading of upper branch stent 206 , as seen in fig6 e , balloon 260 is partially inflated to move upper branch stent 206 through opening 518 . with upper branch stent 206 properly positioned in upper lumen 151 , balloon 260 is then fully expanded so that upper branch stent 206 expands to fully open upper branch lumen 151 . balloon 260 is then deflated and pulled percutaneously in proximal direction 514 and removed from arteries 127 . fig6 f shows branch stent 206 fully expanded in branch lumen 151 and balloon 260 being removed in direction 514 . referring to fig7 a , assembly 700 has been positioned and expanded so that proximal stent 202 is positioned in proximal lumen 129 and distal stent 208 is positioned in distal lumen 125 . a catheter 262 spans from distal lumen 125 through proximal lumen 129 and is positioned adjacent to upper branch lumen 151 with upper branch stent 206 surrounding balloon 260 . in embodiments , as seen in fig7 b , catheter 262 is pulled in a proximal direction 710 until the distal portion of catheter 262 is fully contained within balloon 260 . catheter 262 is then moved in a distal direction 712 to cause stretchable material 510 to bulge into upper branch lumen 151 . as seen in fig7 c , balloon 260 has been expanded , thereby expanding upper branch stent 206 , piercing material 510 and creating opening 518 . as seen in fig7 d , balloon 260 has been deflated , leaving upper branch stent 206 partially covered by stent jacket 204 . referring to fig8 a , stent system 800 comprises a jacket having billowing walls 812 that include an upper billowing wall potion 810 . in embodiments , billing walls include a biocompatible adhesive so that upon inflation , balloon 260 presses billowing wall 812 against artery 127 , thereby creating folds in billowing walls 812 . as balloon 260 continues to expand , folds in billowing wall 812 are compressing to adhere to each other and compressed against artery 127 . in distinct contrast , as seen in fig8 c , upper billowing wall portion 810 is adjacent to upper branch lumen 151 , is pressed into branch lumen 151 and does not form adherent folds . as seen in fig8 d further expansion of upper branch stent 206 punctures stent jacket 204 , creating a punctured opening 840 and upper branch stent 206 has opened upper branch lumen 151 . as used herein , the terms proximal and proximally refer to a position and a movement in an upstream direction from lumen 129 toward vessel lumen 151 . as used herein , the terms distal and distally refer to a position and a movement , respectively , in a downstream direction from lumen 151 toward lumen 129 . in embodiments , stent jacket 204 has a thickness of at least about 20 microns and no more than about 200 microns . additional objects , advantages , and novel features of the present invention will become apparent to one ordinarily skilled in the art upon examination of the following examples , which are not intended to be limiting . additionally , each of the various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below finds experimental support in the following examples . it is appreciated that certain features of the invention , which are , for clarity , described in the context of separate embodiments , may also be provided in combination in a single embodiment . conversely , various features of the invention , which are , for brevity , described in the context of a single embodiment , may also be provided separately or in any suitable subcombination . although the invention has been described in conjunction with specific embodiments thereof , it is evident that many alternatives , modifications and variations will be apparent to those skilled in the art . accordingly , it is intended to embrace all such alternatives , modifications and variations that fall within the spirit and broad scope of the appended claims . all publications , patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification , to the same extent as if each individual publication , patent or patent application was specifically and individually indicated to be incorporated herein by reference . in addition , citation or identification of any reference in this application shall not be construed as an admission hat such reference is available as prior art to the present invention .
disclosed is a stent assembly for expanding in vivo vessels , the assembly comprising first and second radially expandable mesh stents , wherein the first stent is separated by a predetermined distance from the second stent and a stent jacket spans the predetermined distance such that a first end of the jacket is operatively associated with the first stent and a second end of the jacket is operatively associated with the second stent .