Abstract:
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.

Description:
RELATIONSHIP TO EXISTING APPLICATIONS 
     This application is a continuation-in-part of PCT Patent Application No. PCT/IB2006/051874 filed May 24, 2006, which in turn claims the benefit of U.S. Provisional Patent Applications Nos. 60/683,788 filed May 24, 2005; 60/716,100 filed Sep. 12, 2005; and 60/742,460 filed Dec. 5, 2005. 
     This application is also a continuation-in-part of pending U.S. patent application Ser. No. 11/582,354 filed Oct. 18, 2006. 
     In addition, this application claims priority from U.S. Provisional Patent Applications Nos. 60/852,392 filed Oct. 18, 2006, 60/860,485 filed Nov. 22, 2006, 60/860,486 filed Nov. 22, 2006 and 60/877,162 filed Dec. 27, 2006. 
     The contents of the above Applications are hereby incorporated by reference as if fully disclosed herein. 
    
    
     FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates generally to stent assemblies that are deployed in bifurcated vessels. 
     While mono-tubular stents have resulted in improved long-term blood flow, stents are associated with severe problems when deployed in a bifurcated lumen, meaning a parent lumen from which a branch vessel splits. It is estimated that 15% to 20% of all stents are deployed at bifurcations. 
     Treatment of stenotic lesions at bifurcations is associated with increased early complications including compromise of either the branch vessel or the parent vessel and increased potential for restenosis. 
     One method for stenting a bifurcating vessel includes placing a first stent having a substantially circular side opening in a parent vessel and a second stent having a flared end for stenting the branch vessel. 
     The first stent is positioned in the lumen of the parent vessel and expanded, after which the second, flared stent is pressed through the side opening of the first stent and expanded in the branch vessel. 
     One drawback of this method is the difficulty of properly aligning the side opening of the first stent with the branch vessel bifurcation so that the branch vessel stent passes into the branch vessel. Another drawback of this system is that the second, flared, stent is difficult to position properly, and may protrude into the blood stream causing thrombosis. 
     Another method of treating bifurcations is called the crush method, an example of which is seen in U.S. Patent application 20050049680 (Fischell et al), the entirety of which is hereby incorporated by reference as if fully disclosed herein. 
     In this method, a first stent is placed into the branch vessel and expanded so that a portion of the stent protrudes into the parent vessel. A second stent is expanded in the parent vessel, crushing the protruding portion of the first stent against the parent vessel wall around the branch vessel opening. 
     If the first stent is not properly crushed, however, the end of the stent will protrude into the bloodstream, often resulting in thrombosis. Additionally, during crushing, the first stent may pull away from the branch vessel so that there is no support of the branch vessel where support is needed most. Finally, the crush method deposits a large amount of metal at the entrance to the branch vessel lumen, where the tissue is thin and often incapable of supporting the metallic bulk, resulting in restenosis. 
     SUMMARY OF THE INVENTION 
     In view of the drawbacks of the prior art stent systems for deployment in bifurcated vessels, it would be advantageous to have a bifurcation stent system that is easy to position, creates minimal resistance to flow, and maintains a minimal amount of metal bulk at the entrance to a branch vessel. 
     Some embodiments of the present invention successfully address at least some of the shortcomings of the prior art by providing a stent assembly comprising two radially expandable mesh stents separated by a distance with a common stent jacket spanning the distance therebetween. 
     In embodiments, the assembly is configured to be positioned so the mesh stents are located in a parent vessel on either side of a branch vessel bifurcation and the jacket spans the lumen associated with a bifurcation. A third contracted mesh stent is passed through an aperture in the jacket into the branch vessel and expanded. The aperture expands so that the third stent remains at least partially covered by the stent jacket and, in addition to the support provided by the stents, the stent jacket spanning between the first, second and third stents supports the stenotic tissue of the bifurcation therebetween. 
     In this manner, the bifurcation is opened without the bulk of more than one layer of metal as may be the case with bifurcation metal stents that are currently in use. 
     In further embodiments, portions of the stent, and/or stent jacket are coated and/or imbued with active pharmaceutical ingredients (APIs) for the purpose of preventing infection, inflammation, coagulation and/or thrombus formation. 
     Optionally, the two separated stents are covered by the jacket and mounted on a single angioplasty balloon and expand simultaneously within the vessel. Additionally, the two stents optionally positioned to stretch the jacket therebetween during expansion so that the jacket remains taut following removal of the balloon. 
     In embodiments in to order to easily form an opening in the stent jacket for passage of the third stent, the jacket is predilated with a balloon or multiple balloons via the “kissing” technique, or through direct dilation of the stents. 
     Additionally, the stents are optionally deployed using any one of several techniques, including inter alia pre dilatation angioplasty, post angioplasty, and the above noted “kissing technique” and direct dilation stenting techniques. 
     In other embodiments an end of the third stent, in an unexpanded state, is pressed into the jacket and the third stent is expanded, thereby stretching a portion of the stent jacket. Thereafter, the expanded jacket portion is punctured by a puncturing instrument, for example an expanding balloon, and the third stent is passed into the branch vessel and expanded. 
     In still other embodiments, a first mesh stent is placed in the parent vessel and the second mesh stent is placed in the branch vessel with a stent jacket passing therebetween. A third stent is passed through the jacket into the parent vessel, distal to the branch vessel, and expanded. 
     In still further embodiments, a stent assembly comprises two radially expandable mesh parent vessel stents separated by a distance with a common stent jacket spanning the distance therebetween; and includes one or more branch vessel stents that are transported, together with the parent vessel stents, to a bifurcation. 
     According to an aspect of the invention, there is provided 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. 
     In embodiments, for example for use in a coronary vessel, the first stent is positioned between at least one millimeter and not more than about 20 millimeters from the second stent. 
     In other embodiments, the first stent is positioned about three millimeters from the second stent  208 . Optionally, the first stent and second stent are placed in positions that stretch the jacket therebetween. 
     In embodiments, upon radial expansion of the first and second stents, the first jacket end expands radially and encircles at least a portion of the first stent and the second end of the jacket expands radially and encircles at least a portion of the second stent. 
     In embodiments, the stent jacket spanning the distance is configured to encircle an axially disposed third stent in a contracted state, the third stent being axially disposed and movably set on a guide wire while the first stent is contracted and the second stent is contracted. 
     In embodiments, the stent jacket spanning the distance is configured to encircle an axially disposed third stent in a contracted state while the assembly is being delivered to an in situ location. 
     In embodiments, the stent jacket spanning the distance is configured to encircle an axially disposed third stent in a contracted state following delivery of the first and second stents to an in situ location. 
     In embodiments, the stent jacket spanning the distance comprises at least one aperture configured to allow passage of the guide wire and the guide wire is configured to be manipulated through the aperture while the third stent is contracted. 
     In embodiments, the at least one aperture is additionally configured to encircle an outer surface of the third stent while the third stent is contracted. 
     In embodiments, the third stent is configured move along the guide wire through the aperture at an angle to an axis running between the first and second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, the mean diameter of the at least one aperture is configured to expand when the contracted third stent is expanded while encircled by the aperture. 
     In embodiments, upon expansion of the third stent, at least a portion of the stent jacket spanning the distance is configured to encircle at least a portion of an outer surface of the third stent. 
     In embodiments, during expansion, the first stent and the second stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the first stent and the second stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of about 15 atmospheres. 
     In embodiments, during expansion, the third stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the third stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of about 15 atmospheres. 
     In embodiments, during expansion, the first stent and the third stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the first stent and the third stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of about 15 atmospheres. 
     In embodiments, during expansion, the second stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the second stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of about 15 atmospheres. 
     In embodiments, the third stent, while contracted, is configured to move along the guide wire and, following expansion of the first stent and the second stent, to have an end pressed into a portion of the stent jacket. 
     In embodiments, pressed portion of the stent jacket is configured to stretch when the third stent is expanded during the pressing. 
     In embodiments, the stretched portion of the stent jacket is configured to be punctured by a puncturing tool, wherein the resulting puncture is of a sufficient diameter to allow the third stent to pass through the puncture. 
     In embodiments, the third stent is configured to pass through the puncture at an angle to an axis running between the first and second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, a portion of the stent jacket spanning the distance remains substantially intact following the puncturing. 
     In embodiments, portions of the intact portion form at least one fold as a result of at least one of: 
     prior to the puncturing, 
     during the puncturing, and 
     following the puncturing. 
     In embodiments, at least a portion of the intact portion includes a pressure-sensitive self-adhering adhesive. 
     In embodiments, the adhesive is an adhesive from the group of adhesives comprising: fibrin, biological glue, collagen, hydrogel, hydrocolloid, collagen alginate, and methylcellulose. 
     In embodiments, at least a portion of the at least one fold is configured to adhere in response to pressure of at least about one atmosphere and no more than about 20 atmospheres. 
     In embodiments, the puncturing tool comprises an expandable balloon. 
     In embodiments, the stent jacket spanning the distance comprises at least one aperture configured to encircle the expandable balloon in a contracted state. 
     In embodiments, the at least one aperture is configured and to rip as the expandable balloon is inflated. 
     In embodiments, upon passage of the third stent through the puncture, at least a portion of the jacket is configured to encircle at least a portion of an outer surface of the third stent. 
     In embodiments, during expansion, the first stent and the second stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the first stent and the second stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of about 15 atmospheres. 
     In embodiments, during expansion, the third stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the third stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of about 15 atmospheres. 
     In embodiments, during expansion, the first stent and the third stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the first stent and the third stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of about 15 atmospheres. 
     In embodiments, during expansion, the second stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the second stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of about 15 atmospheres. 
     In embodiments, a first portion of the stent jacket spanning the distance is configured to encircle an axially disposed third stent in a contracted state while the assembly is being delivered to an in situ location. 
     In embodiments, the third stent is set at an angle to an axis passing through the first stent and the second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, during expansion, the third stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the third stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of about 15 atmospheres. 
     In embodiments, upon expansion, the third stent is configured to assume an angle to an axis passing through the first stent and the second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, a second portion of the stent jacket spanning the distance is configured to additionally encircle an axially disposed fourth stent in a contracted state while the assembly is being delivered to an in situ location. 
     In embodiments, the fourth stent is set at an angle to an axis passing through the first stent and the second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, the third stent is positioned to expand substantially outward and substantially radially opposite to the expansion of the fourth stent. 
     In embodiments, during expansion, the fourth stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the fourth stent is of a sufficient diameter to press at least a portion of the inner walls of a branch vessel with a pressure of about 15 atmospheres. 
     In embodiments, upon expansion, the fourth stent is configured to assume an angle to an axis passing through the first stent and the second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, during expansion, the first stent and the second stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of at least one atmosphere and no more than about 50 atmospheres. 
     In embodiments, during expansion, the first stent and the second stent are of a sufficient diameter to press at least a portion of the inner walls of a parent vessel with a pressure of about 15 atmospheres. 
     In embodiments, the stents 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, the stents are selected from the group consisting of: a cardiovascular stent, a coronary stent, a peripheral stent, an abdominal aortic aneurysm stent, a cerebral stent, a carotid stent, an endovascular stent, an aortic valve stent, and a pulmonary valve stent. 
     In embodiments, the stent jacket comprises a material manufactured by a process from the group consisting of: interlacing knitting, interlocked knitting, braiding, interlacing, and/or dipping a porous mold into one or more reagents. 
     In embodiments, during expansion said stents are configured to expand in a manner that dilates the adjacent lumens. 
     In embodiments, following expansion the lumens are supported by one layer of stent metal. 
     According to an aspect of the present invention, there is provided a method for manufacturing a stent assembly for expanding in vivo vessel lumens, the method comprising: providing two axially aligned radially expandable mesh stents, comprising a first stent and a second stent, at a distance from each other, attaching a first end of a stent jacket to the first stent, and attaching a second end of the stent jacket to the second stent, such that an intermediate portion of the jacket spans the distance. 
     In embodiments, the method includes encircling a third stent in a contracted state coaxially aligned within the jacket. 
     In embodiments, the method includes axially setting the third stent within the jacket at an angle to an axis running between the first and second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, the method includes encircling a fourth stent in a contracted state within the jacket. 
     In embodiments, the method includes axially setting the fourth stent within the jacket at an angle to an axis running between the first and second stent of at least about 15 degrees and no more than about 165 degrees. 
     In embodiments, the method includes positioning the third stent to expand substantially radially opposite to the expansion of the fourth stent. 
     In embodiments, the radially expandable stent comprises 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, the radially expandable stent comprises a bio degradable/bio-absorbable base from the group consisting of: PGLA, PLLA, PLA, bio-resorbable magnesium, or other bio resorbable compounds. 
     In embodiments, the jacket and the stents comprise a material selected from the group consisting of: polyethylene, polyvinyl chloride, polyurethane, nylon and a biocompatible polymer fiber. 
     In embodiments, the jacket and the stents comprise a material selected from the group consisting of: nitinol, stainless steel shape memory materials, metals, synthetic biostable polymer, a natural polymer, and an inorganic material. In embodiments, the biostable polymer comprises a material from the group consisting of: a polyolefin, a polyurethane, a fluorinated polyolefin, a chlorinated polyolefin, a polyamide, an acrylate polymer, an acrylamide polymer, a vinyl polymer, a polyacetal, a polycarbonate, a polyether, a polyester, an aromatic polyester, a polysulfone, and a silicone rubber. 
     In embodiments, the natural polymer comprises a material from the group consisting of: a polyolefin, a polyurethane, a Mylar, a silicone, and a fluorinated polyolefin. 
     In embodiments, the jacket and the stents comprise a material having a property selected from the group consisting of: compliant, flexible, plastic, and rigid. 
     In embodiments, the assembly includes an active pharmaceutical ingredient. 
     In embodiments, the API comprises a chemotherapeutic selected from the group consisting of peptides, proteins, nucleic acids, monoclonal antibodies, L-cell agonists, super oxide dismutase Interleukin-10, glucorticoids, sulphazalazine, calcitonin, insulin, 5-fluoracil, leucovorin, fluoropyrimidine S-1, 2′-deoxycytidine, analgesics, antibacterials, antibiotics, antidepressants, antihistamines, antihelminths, anti-inflammatory agents, antiirritants, antilipemics, antimicrobials, antimycotics, antioxidants, antipruritics, antiseptic, antiswelling agents, antiviral agents, antiyeast agents, astringents, topical cardiovascular agents, chemotherapeutic agents, corticosteroids, fungicides, hormones, hydroxyacids, lactams, non-steroidal anti-inflammatory agents, progestins, statines, sanatives and vasodilators and mixtures thereof. 
     In embodiments, the API comprises an analgesic selected from the group consisting of benzocaine, butamben picrate, dibucaine, dimethisoquin, dyclonine, lidocaine, pramoxine, tetracaine, salicylates and derivatives, esters, salts and mixtures thereof. 
     In embodiments, the API comprises an antibiotic selected from the group consisting of amanfadine hydrochloride, amanfadine sulfate, amikacin, amikacin sulfate, aminoglycosides, amoxicillin, ampicillin, ansamycins, bacitracin, beta-lactams, candicidin, capreomycin, carbenicillin, cephalexin, cephaloridine, cephalothin, cefazolin, cephapirin, cephradine, cephaloglycin, chloramphenicols, chlorhexidine, chlorhexidine gluconate, chlorhexidine hydrochloride, chloroxine, chlorquinaldol, chlortetracycline, chlortetracycline hydrochloride, ciprofloxacin, circulin, clindamycin, clindamycin hydrochloride, clotrimazole, cloxacillin, demeclocycline, diclosxacillin, diiodohydroxyquin, doxycycline, ethambutol, ethambutol hydrochloride, erythromycin, erythromycin estolate, erythromycin stearate, farnesol, floxacillin, gentamicin, gentamicin sulfate, gramicidin, griseofulvin, haloprogin, haloquinol, hexachlorophene, iminocylcline, iodochlorhydroxyquin, kanamycin, kanamycin sulfate, lincomycin, lineomycin, lineomycin hydrochloride, macrolides, meclocycline, methacycline, methacycline hydrochloride, methenamine, methenamine hippurate, methenamine mandelate, methicillin, metronidazole, miconazole, miconazole hydrochloride, minocycline, minocycline hydrochloride, mupirocin, nafcillin, neomycin, neomycin sulfate, netilmicin, netilmicin sulfate, nitrofurazone, norfloxacin, nystatin, octopirox, oleandomycin, orcephalosporins, oxacillin, oxytetracycline, oxytetracycline hydrochloride, parachlorometa xylenol, paromomycin, paromomycin sulfate, penicillins, penicillin G, penicillin V, pentamidine, pentamidine hydrochloride, phenethicillin, polymyxins, quinolones, streptomycin sulfate, tetracycline, tobramycin, tolnaftate, triclosan, trifampin, rifamycin, rolitetracycline, spectinomycin, spiramycin, streptomycin, sulfonamide, tetracyclines, tetracycline, tobramycin, tobramycin sulfate, triclocarbon, triclosan, trimethoprim-sulfamethoxazole, tylosin, vancomycin, yrothricin and derivatives, esters, salts and mixtures thereof 
     In embodiments, the API comprises an antihistamine selected from the group consisting of chlorcyclizine, diphenhydramine, mepyramine, methapyrilene, tripelennamine and derivatives, esters, salts and mixtures thereof. 
     In embodiments, the API comprises a corticosteroid selected from the group consisting of alclometasone dipropionate, amcinafel, amcinafide, amcinonide, beclomethasone, beclomethasone dipropionate, betamethsone, betamethasone benzoate, betamethasone dexamethasone-phosphate, dipropionate, betamethasone valerate, budesonide, chloroprednisone, chlorprednisone acetate, clescinolone, clobetasol, clobetasol propionate, clobetasol valerate, clobetasone, clobetasone butyrate, clocortelone, cortisone, cortodoxone, craposone butyrate, desonide, desoxymethasone, dexamethasone, desoxycorticosterone acetate, dichlorisone, diflorasone diacetate, diflucortolone valerate, diflurosone diacetate, diflurprednate, fluadrenolone, flucetonide, flucloronide, fluclorolone acetonide, flucortine butylesters, fludroxycortide, fludrocortisone, flumethasone, flumethasone pivalate, flumethasone pivalate, flunisolide, fluocinolone, fluocinolone acetonide, fluocinonide, fluocortin butyl, fluocortolone, fluorometholone, fluosinolone acetonide, fluperolone, fluprednidene acetate, fluprednisolone hydrocortamate, fluradrenolone, fluradrenolone acetonide, flurandrenolone, fluticasone, halcinonide, halobetasol, hydrocortisone, hydrocortisone acetate, hydrocortisone butyrate, hydrocortisone cyclopentylpropionate, hydrocortisone valerate, hydroxyltriamcinolone, medrysone, meprednisone, α-methyl dexamethasone, methylprednisolone, methylprednisolone acetate, mometasone furoate, paramethasone, prednisolone, prednisone, pregnenolone, progesterone, spironolactone, triamcinolone, triamcinolone acetonide and derivatives, esters, salts and mixtures thereof. 
     In embodiments, the API comprises a hormone selected from the group consisting of methyltestosterone, androsterone, androsterone acetate, androsterone propionate, androsterone benzoate, androsteronediol, androsteronediol-3-acetate, androsteronediol-17-acetate, androsteronediol 3-17-diacetate, androsteronediol-17-benzoate, androsteronedione, androstenedione, androstenediol, dehydroepiandrosterone, sodium dehydroepiandrosterone sulfate, dromostanolone, dromostanolone propionate, ethylestrenol, fluoxymesterone, nandrolone phenpropionate, nandrolone decanoate, nandrolone furylpropionate, nandrolone cyclohexane-propionate, nandrolone benzoate, nandrolone cyclohexanecarboxylate, androsteronediol-3-acetate-1-7-benzoate, oxandrolone, oxymetholone, stanozolol, testosterone, testosterone decanoate, 4-dihydrotestosterone, 5a-dihydrotestosterone, testolactone, 17a-methyl-19-nortestosterone, desogestrel, dydrogesterone, ethynodiol diacetate, medroxyprogesterone, levonorgestrel, medroxyprogesterone acetate, hydroxyprogesterone caproate; norethindrone, norethindrone acetate, norethynodrel, allylestrenol, 19-nortestosterone, lynoestrenol, quingestanol acetate, medrogestone, norgestrienone, dimethisterone, ethisterone, cyproterone acetate, chlormadinone acetate, megestrol acetate, norgestimate, norgestrel, desogrestrel, trimegestone, gestodene, nomegestrol acetate, progesterone, 5a-pregnan-3b,20a-diol sulfate, 5a-pregnan-3b,20b-diol sulfate, 5a-pregnan-3b.-ol-20-one, 16,5a-pregnen-3b-ol-20-one, 4-pregnen-20b-ol-3-one-20-sulfate, acetoxypregnenolone, anagestone acetate, cyproterone, dihydrogesterone, flurogestone acetate, gestadene, hydroxyprogesterone acetate, hydroxymethylprogesterone, hydroxymethyl progesterone acetate, 3-ketodesogestrel, megestrol, melengestrol acetate, norethisterone and derivatives, esters, salts and mixtures thereof. 
     In embodiments, the API comprises a non-steroidal anti-inflammatory agent selected from the group consisting of azelaic acid, oxicams, piroxicam, isoxicam, tenoxicam, sudoxicam, CP-14,304, salicylates, aspirin, disalcid, benorylate, trilisate, safapryn, solprin, diflunisal, fendosal, acetic acid derivatives, diclofenac, fenclofenac, indomethacin, sulindac, tolmetin, isoxepac, furofenac, tiopinac, zidometacin, acematacin, fentiazac, zomepirac, clindanac, oxepinac, felbinac, ketorolac, fenamates, mefenamic, meclofenamic, flufenamic, niflumic, tolfenamic acids, propionic acid derivatives, ibuprofen, naproxen, benoxaprofen, flurbiprofen, ketoprofen, fenoprofen, fenbufen, indopropfen, pirprofen, carprofen, oxaprozin, pranoprofen, miroprofen, tioxaprofen, suprofen, alminoprofen, tiaprofen, pyrazoles, phenylbutazone, oxyphenbutazone, feprazone, azapropazone, trimethazone and derivatives, esters, salts and mixtures thereof. 
     In embodiments, the API comprises a vasodilator selected from the group consisting of ethyl nicotinate, capsicum extract and derivatives, esters, salts and mixtures thereof. In embodiments, the stent assembly includes a low-bulk mesh jacket designed to promote a stable layer of endothelial cells. 
     In embodiments, the mesh comprises fiber having a low diameter that allows each endothelial cell to fully cover and overlap each fiber, thereby forming a layer of endothelial cells that adhere to tissue on either side of the fiber. The thus formed endothelial layer is substantially stable with a substantially reduced tendency to break away and form emboli. 
     In embodiments, the mesh fiber comprises material that encourages adherence of endothelial cells, thereby encouraging endothelial layer stability. 
     In embodiments, each mesh fiber is spaced a distance from a neighboring fiber thereby preventing a single endothelial cell from adhering to more than one fiber, thereby reducing the chance that endothelial cells will break free of the stent, for example as a result of natural stent pulsation during blood flow. 
     In embodiments, the stent jacket optionally comprises a mesh that is knitted. In accordance with some embodiments of the present invention, the stent jacket mesh is optionally formed from a single fiber or a single group of fibers. 
     In embodiments, the stent assembly includes a stent jacket comprising an expansible mesh structure, formed of fibers of a diameter between about 7 micrometers and about 18 micrometers, the diameter having a property of forming a substantially stable layer of endothelial cells, covering the fibers, thus reducing platelet aggregation, and an expansible stent, operatively associated with the stent jacket. 
     In embodiments, the fiber diameter is between about 10 micrometers and bout 15 micrometers. 
     In embodiments, the fiber diameter is between about 11 micrometers and bout 14 micrometers. 
     In embodiments, the fiber diameter is between about 12 micrometers and bout 13 micrometers. 
     In embodiments, the fiber diameter is between about 12.5 micrometers. In embodiments, the mesh is formed as a single knit. In embodiments, the fiber is formed from multiple filaments. 
     In embodiments, the mesh jacket structure comprises a retracted state and a deployed state, and further in the deployed state, the mesh structure defines apertures having a minimum center dimension, which is greater than about 180 micrometers, thus minimizing occurrences of a single endothelial cell adhering to more than one fiber, across one of the apertures, and reducing a chance of endothelial cells breaking free as a result of natural stent pulsation with blood flow. 
     In embodiments, the minimum center dimension is greater than about 200 micrometers. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
     As used herein, the terms “comprising” and “including” or grammatical variants thereof are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof. This term encompasses the terms “consisting of” and “consisting essentially of”. 
     The phrase “consisting essentially of” or grammatical variants thereof when used herein are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof but only if the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed composition, device or method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention of stent assemblies configured for assembling in bifurcating vessels is herein described, by way of example only, with reference to the accompanying drawings. 
       With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
       In the drawings: 
         FIGS. 1   a - 1   d  show deployment of prior art stents in bifurcating vessels; 
         FIGS. 2   a - 2   e  show stents and stent jackets being deployed in cross sections of bifurcating vessels, according to embodiments of the invention; and 
         FIGS. 3   a - 8   d  show alternative embodiments of the stents and stent jackets of  FIG. 2   e  being deployed in cross sections of bifurcating vessels, according to embodiments of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     Referring now to the drawings: 
     In  FIG. 1   a , arteries  127  form an upper branch vessel lumen  151 , a proximal parent vessel lumen  129  and a distal parent vessel lumen  125 . 
       FIGS. 1   b - 1   d  show the crush method, noted above, for treating a bifurcation. As seen in  FIG. 1   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  FIG. 1   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  FIG. 1   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  FIG. 2   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  FIG. 2   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  FIG. 2   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  FIG. 2   d , branch stent  206  positioned on balloon  260  has been pressed into stent jacket  204 , through one of apertures  103 . As seen in  FIG. 2   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  ( FIG. 2   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. 
       FIG. 3   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  FIG. 3   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  FIG. 3   b , distal parent vessel stent  208  is pushed through apertures  103 . As seen in  FIG. 3   c  and distal parent vessel stent  208  has been expanded in distal lumen  125 . 
     Referring to  FIG. 4   a , arteries  127  include a lower side branch lumen  152 . As seen in  FIG. 4   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  FIG. 4   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  FIG. 4   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  FIG. 4   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  FIG. 5   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  FIG. 5   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  FIG. 5   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  FIG. 5   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  FIG. 5   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  FIG. 6   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  FIG. 6   b , balloon  260 , has been pressed into stretchable material  510 , causing stent jacket  204  to bulge into upper branch lumen  151 . 
     In  FIG. 6   c , balloon  260  has been fully expanded, thereby puncturing material  510  and creating opening  518 . In  FIG. 6   d , balloon  260  has been partially deflated and pulled downward in direction  514 . Following loading of upper branch stent  206 , as seen in  FIG. 6   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 .  FIG. 6   f  shows branch stent  206  fully expanded in branch lumen  151  and balloon  260  being removed in direction  514 . 
     Referring to  FIG. 7   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  FIG. 7   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  FIG. 7   c , balloon  260  has been expanded, thereby expanding upper branch stent  206 , piercing material  510  and creating opening  518 . As seen in  FIG. 7   d , balloon  260  has been deflated, leaving upper branch stent  206  partially covered by stent jacket  204 . 
     Referring to  FIG. 8   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  FIG. 8   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  FIG. 8   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 that such reference is available as prior art to the present invention.