ES2662408T3 - Métodos de engarce de stent - Google Patents

Métodos de engarce de stent Download PDF

Info

Publication number
ES2662408T3
ES2662408T3 ES15194138.2T ES15194138T ES2662408T3 ES 2662408 T3 ES2662408 T3 ES 2662408T3 ES 15194138 T ES15194138 T ES 15194138T ES 2662408 T3 ES2662408 T3 ES 2662408T3
Authority
ES
Spain
Prior art keywords
stent
diameter
balloon
approximately
crimping
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
ES15194138.2T
Other languages
English (en)
Spanish (es)
Inventor
Boyd V. Knott
Samit R. Kadakia
Leopoldo Ortega
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Abbott Cardiovascular Systems Inc
Original Assignee
Abbott Cardiovascular Systems Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abbott Cardiovascular Systems Inc filed Critical Abbott Cardiovascular Systems Inc
Application granted granted Critical
Publication of ES2662408T3 publication Critical patent/ES2662408T3/es
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
    • A61F2/9522—Means for mounting a stent or stent-graft onto or into a placement instrument
    • A61F2/9524—Iris-type crimpers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
    • A61F2/9522—Means for mounting a stent or stent-graft onto or into a placement instrument
    • A61F2/9526—Means for mounting a stent or stent-graft onto or into a placement instrument using a mandrel
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
    • A61F2/958—Inflatable balloons for placing stents or stent-grafts
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
    • A61F2/9522—Means for mounting a stent or stent-graft onto or into a placement instrument
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49826—Assembling or joining
    • Y10T29/49908—Joining by deforming
    • Y10T29/49925—Inward deformation of aperture or hollow body wall
    • Y10T29/49927—Hollow body is axially joined cup or tube
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/53—Means to assemble or disassemble
    • Y10T29/53909—Means comprising hand manipulatable tool
    • Y10T29/53943—Hand gripper for direct push or pull
    • Y10T29/53952—Tube sleeve or ferrule applying or removing

Landscapes

  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Cardiology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Media Introduction/Drainage Providing Device (AREA)
  • Materials For Medical Uses (AREA)
ES15194138.2T 2010-09-30 2011-09-12 Métodos de engarce de stent Active ES2662408T3 (es)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US895646 1978-04-12
US12/895,646 US8595913B2 (en) 2010-09-30 2010-09-30 Stent crimping methods

Publications (1)

Publication Number Publication Date
ES2662408T3 true ES2662408T3 (es) 2018-04-06

Family

ID=44674897

Family Applications (2)

Application Number Title Priority Date Filing Date
ES15194138.2T Active ES2662408T3 (es) 2010-09-30 2011-09-12 Métodos de engarce de stent
ES11760634.3T Active ES2567677T3 (es) 2010-09-30 2011-09-12 Métodos de engarce de stent

Family Applications After (1)

Application Number Title Priority Date Filing Date
ES11760634.3T Active ES2567677T3 (es) 2010-09-30 2011-09-12 Métodos de engarce de stent

Country Status (5)

Country Link
US (2) US8595913B2 (enExample)
EP (2) EP3009109B1 (enExample)
JP (2) JP6068346B2 (enExample)
ES (2) ES2662408T3 (enExample)
WO (1) WO2012044454A1 (enExample)

Families Citing this family (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8597716B2 (en) 2009-06-23 2013-12-03 Abbott Cardiovascular Systems Inc. Methods to increase fracture resistance of a drug-eluting medical device
US8261423B2 (en) 2010-04-30 2012-09-11 Abbott Cardiovascular Systems Inc. Methods for crimping a polymeric stent onto a delivery balloon
US8752261B2 (en) * 2010-07-07 2014-06-17 Abbott Cardiovascular Systems Inc. Mounting stents on stent delivery systems
US8539663B2 (en) 2010-08-23 2013-09-24 Abbott Cardiovascular Systems Inc. Reducing crimping damage to polymer scaffold
US8595913B2 (en) * 2010-09-30 2013-12-03 Advanced Cardiovascular Systems, Inc. Stent crimping methods
US8961848B2 (en) 2011-04-18 2015-02-24 Abbott Cardiovascular Systems Inc. Methods for increasing a retention force between a polymeric scaffold and a delivery balloon
US9199408B2 (en) 2012-04-03 2015-12-01 Abbott Cardiovascular Systems Inc. Uniform crimping and deployment methods for polymer scaffold
US20120290063A1 (en) 2011-05-09 2012-11-15 Abbott Cardiovascular Systems Inc. Method of Increasing Stent Retention of Bioabsorbable Scaffolding with a Sheath
US8752265B2 (en) 2011-05-13 2014-06-17 Abbott Cardiovascular Systems Inc. Methods for crimping a polymeric scaffold to a delivery balloon and achieving stable mechanical properties in the scaffold after crimping
US8726483B2 (en) 2011-07-29 2014-05-20 Abbott Cardiovascular Systems Inc. Methods for uniform crimping and deployment of a polymer scaffold
US9283100B2 (en) 2012-05-16 2016-03-15 Abbott Cardiovascular Systems Inc. Polymer scaffold with multi-pleated balloon
JP6026776B2 (ja) * 2012-05-25 2016-11-16 株式会社グッドマン ステントデリバリカテーテルの製造方法及びステント取付装置
US9724219B2 (en) 2012-10-04 2017-08-08 Abbott Cardiovascular Systems Inc. Method of uniform crimping and expansion of medical devices
JP6267214B2 (ja) * 2012-10-25 2018-01-24 アルテリアル・ルモンドラン・テクノロジー・エス・アー 生体再吸収性ステントをクリンプする方法
US10195025B2 (en) * 2014-05-12 2019-02-05 Edwards Lifesciences Corporation Prosthetic heart valve
US9527234B2 (en) 2014-10-02 2016-12-27 Inspiremd, Ltd. Stent thermoforming apparatus and methods
US10143573B2 (en) * 2015-12-17 2018-12-04 Abbott Cardiovascular Systems Inc. Thin-walled scaffolds having flexible distal end
US9956099B2 (en) 2015-12-17 2018-05-01 Abbott Cardiovascular Systems Inc. Thin-walled scaffolds having reduced crimp profile and carrying radiopaque markers
US9861507B2 (en) * 2015-12-17 2018-01-09 Abbott Cardiovascular Systems Inc. Thin-walled scaffolds having modified marker structure near distal end
US10660773B2 (en) 2017-02-14 2020-05-26 Abbott Cardiovascular Systems Inc. Crimping methods for thin-walled scaffolds
US10555825B2 (en) 2017-11-09 2020-02-11 Abbott Cardiovascular Systems Inc. Rotation of a medical device during crimping
US10967556B2 (en) * 2018-06-11 2021-04-06 Abbott Cardiovascular Systems Inc. Uniform expansion of thin-walled scaffolds
DE102018129917A1 (de) * 2018-11-27 2020-05-28 Biotronik Ag Verfahren zum maschinellen Vorcrimpen von Stents, insbesondere medikamentenbeschichteten Stents
DE102018129919A1 (de) * 2018-11-27 2020-05-28 Biotronik Ag Verfahren zum maschinellen Repositionieren eines vorgecrimpten medikamentenbeschichteten Stents
CN117915871A (zh) * 2021-08-06 2024-04-19 高级分支系统股份有限公司 用于处理分叉的完全压接支架
CN118103009A (zh) 2021-10-12 2024-05-28 波士顿科学国际有限公司 用于压缩和加载支架的装置和方法
WO2023064362A1 (en) 2021-10-13 2023-04-20 Boston Scientific Scimed, Inc. Device and method for compressing and loading a stent
CN115137535A (zh) * 2022-06-14 2022-10-04 南京浩衍鼎业科技技术有限公司 一种用于安全压握生物可吸收支架的方法

Family Cites Families (58)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US179867A (en) 1876-07-18 Improvement in canal-banks
US5876445A (en) * 1991-10-09 1999-03-02 Boston Scientific Corporation Medical stents for body lumens exhibiting peristaltic motion
US5836965A (en) 1994-10-19 1998-11-17 Jendersee; Brad Stent delivery and deployment method
US5913871A (en) 1996-09-25 1999-06-22 Medtronic, Inc. Balloon modification for improved stent fixation and deployment
US5976181A (en) 1997-09-22 1999-11-02 Ave Connaught Balloon mounted stent and method therefor
US5992000A (en) * 1997-10-16 1999-11-30 Scimed Life Systems, Inc. Stent crimper
US6179867B1 (en) * 1998-01-16 2001-01-30 Advanced Cardiovascular Systems, Inc. Flexible stent and method of use
US6063092A (en) 1998-04-07 2000-05-16 Medtronic Inc. Heat set and crimping process to optimize stent retention
US6296655B1 (en) 1998-04-27 2001-10-02 Advanced Cardiovascular Systems, Inc. Catheter balloon with biased multiple wings
US20010014821A1 (en) 1998-11-16 2001-08-16 Mohamad Ike Juman Balloon catheter and stent delivery system having enhanced stent retention
US6312459B1 (en) * 1999-06-30 2001-11-06 Advanced Cardiovascular Systems, Inc. Stent design for use in small vessels
US6629350B2 (en) * 2000-06-08 2003-10-07 Tom Motsenbocker Stent crimping apparatus and method
AU6357501A (en) 2000-08-23 2002-02-28 Cordis Corporation Low profile mounting method for low profile balloon expandable stents
US7572270B2 (en) 2001-02-16 2009-08-11 Cordis Corporation Balloon catheter stent delivery system with ridges
WO2002066095A2 (en) 2001-02-16 2002-08-29 Cordis Corporation Method of balloon catheter stent delivery system with ridges
US6739033B2 (en) 2001-03-29 2004-05-25 Scimed Life Systems, Inc. Thermal regulation of a coated work-piece during the reconfiguration of the coated work-piece
US6666880B1 (en) 2001-06-19 2003-12-23 Advised Cardiovascular Systems, Inc. Method and system for securing a coated stent to a balloon catheter
US6863683B2 (en) 2001-09-19 2005-03-08 Abbott Laboratoris Vascular Entities Limited Cold-molding process for loading a stent onto a stent delivery system
EP1551333A4 (en) 2002-06-13 2010-01-06 Existent Inc GUIDE WIRE SYSTEM
US7343659B2 (en) * 2002-07-10 2008-03-18 Boston Scientific Scimed, Inc. Method of making a medical device
US6745445B2 (en) 2002-10-29 2004-06-08 Bard Peripheral Vascular, Inc. Stent compression method
US7156869B1 (en) * 2003-01-27 2007-01-02 Advanced Cardiovascular Systems, Inc. Drug-eluting stent and delivery system with tapered stent in shoulder region
US7487579B2 (en) 2003-03-12 2009-02-10 Boston Scientific Scimed, Inc. Methods of making medical devices
US20050118344A1 (en) 2003-12-01 2005-06-02 Pacetti Stephen D. Temperature controlled crimping
JP2007512908A (ja) * 2003-12-01 2007-05-24 アドヴァンスド カーディオヴァスキュラー システムズ, インコーポレイテッド 温度調整式圧着法
US7225518B2 (en) * 2004-02-23 2007-06-05 Boston Scientific Scimed, Inc. Apparatus for crimping a stent assembly
WO2006017057A2 (en) * 2004-07-09 2006-02-16 Conor Medsystems, Inc. Balloon catheter system for securing a stent
US8597716B2 (en) 2009-06-23 2013-12-03 Abbott Cardiovascular Systems Inc. Methods to increase fracture resistance of a drug-eluting medical device
US8012402B2 (en) 2008-08-04 2011-09-06 Abbott Cardiovascular Systems Inc. Tube expansion process for semicrystalline polymers to maximize fracture toughness
US7731890B2 (en) 2006-06-15 2010-06-08 Advanced Cardiovascular Systems, Inc. Methods of fabricating stents with enhanced fracture toughness
US9283099B2 (en) * 2004-08-25 2016-03-15 Advanced Cardiovascular Systems, Inc. Stent-catheter assembly with a releasable connection for stent retention
US7648727B2 (en) * 2004-08-26 2010-01-19 Advanced Cardiovascular Systems, Inc. Methods for manufacturing a coated stent-balloon assembly
EP1819301A4 (en) * 2004-12-08 2012-10-17 Innovational Holdings Llc MEDICAL DEVICE EXTENDABLE TO DIFFERENT ARTICULATION PERFORMANCE
US7316148B2 (en) 2005-02-15 2008-01-08 Boston Scientific Scimed, Inc. Protective sheet loader
US7947207B2 (en) 2005-04-12 2011-05-24 Abbott Cardiovascular Systems Inc. Method for retaining a vascular stent on a catheter
US7763198B2 (en) * 2005-04-12 2010-07-27 Abbott Cardiovascular Systems Inc. Method for retaining a vascular stent on a catheter
US7563400B2 (en) 2005-04-12 2009-07-21 Advanced Cardiovascular Systems, Inc. Method of stent mounting to form a balloon catheter having improved retention of a drug delivery stent
US7951185B1 (en) 2006-01-06 2011-05-31 Advanced Cardiovascular Systems, Inc. Delivery of a stent at an elevated temperature
US20090076594A1 (en) 2006-03-14 2009-03-19 Patrick Sabaria Method of monitoring positioning of polymer stents
US7761968B2 (en) 2006-05-25 2010-07-27 Advanced Cardiovascular Systems, Inc. Method of crimping a polymeric stent
US20070282433A1 (en) 2006-06-01 2007-12-06 Limon Timothy A Stent with retention protrusions formed during crimping
US8333000B2 (en) * 2006-06-19 2012-12-18 Advanced Cardiovascular Systems, Inc. Methods for improving stent retention on a balloon catheter
US20080033523A1 (en) 2006-07-10 2008-02-07 Gale David C Stent crack reduction
US20080033524A1 (en) 2006-07-11 2008-02-07 Gale David C Heated balloon assembly for delivery of polymeric stents
US7886419B2 (en) 2006-07-18 2011-02-15 Advanced Cardiovascular Systems, Inc. Stent crimping apparatus and method
US8099849B2 (en) 2006-12-13 2012-01-24 Abbott Cardiovascular Systems Inc. Optimizing fracture toughness of polymeric stent
US8002817B2 (en) 2007-05-04 2011-08-23 Abbott Cardiovascular Systems Inc. Stents with high radial strength and methods of manufacturing same
US8388673B2 (en) 2008-05-02 2013-03-05 Abbott Cardiovascular Systems Inc. Polymeric stent
US7673379B1 (en) * 2007-05-11 2010-03-09 Abbott Cardiovascular Systems Inc. Method of producing a stent-balloon assembly
US7666342B2 (en) 2007-06-29 2010-02-23 Abbott Cardiovascular Systems Inc. Method of manufacturing a stent from a polymer tube
US8046897B2 (en) * 2007-09-28 2011-11-01 Abbott Cardiovascular Systems Inc. Method and apparatus for stent retention on a balloon catheter
US8261420B2 (en) * 2008-05-13 2012-09-11 Abbott Laboratories Method and apparatus for reducing stress during stent manufacture
US8123793B2 (en) * 2008-09-10 2012-02-28 Boston Scientific Scimed, Inc. Pre-crimp balloon inflation
US8844113B2 (en) 2010-04-30 2014-09-30 Abbott Cardiovascular Systems, Inc. Methods for crimping a polymeric stent scaffold onto a delivery balloon
US8261423B2 (en) 2010-04-30 2012-09-11 Abbott Cardiovascular Systems Inc. Methods for crimping a polymeric stent onto a delivery balloon
US8752261B2 (en) 2010-07-07 2014-06-17 Abbott Cardiovascular Systems Inc. Mounting stents on stent delivery systems
US8539663B2 (en) 2010-08-23 2013-09-24 Abbott Cardiovascular Systems Inc. Reducing crimping damage to polymer scaffold
US8595913B2 (en) * 2010-09-30 2013-12-03 Advanced Cardiovascular Systems, Inc. Stent crimping methods

Also Published As

Publication number Publication date
JP6068346B2 (ja) 2017-01-25
US8595913B2 (en) 2013-12-03
EP2621415A1 (en) 2013-08-07
ES2567677T3 (es) 2016-04-26
JP2017080460A (ja) 2017-05-18
JP6390872B2 (ja) 2018-09-19
JP2013541980A (ja) 2013-11-21
US20120079706A1 (en) 2012-04-05
US9308106B2 (en) 2016-04-12
EP3009109A1 (en) 2016-04-20
HK1187232A1 (zh) 2014-04-04
US20140059834A1 (en) 2014-03-06
EP3009109B1 (en) 2018-01-24
WO2012044454A1 (en) 2012-04-05
EP2621415B1 (en) 2016-01-13

Similar Documents

Publication Publication Date Title
ES2567677T3 (es) Métodos de engarce de stent
US7572270B2 (en) Balloon catheter stent delivery system with ridges
CN105120796B (zh) 减少外周植入支撑架中的回缩
CN104884004B (zh) 可生物再吸收支架的压握方法
US6942681B2 (en) Method of balloon catheter stent delivery system with ridges
JP2015516196A (ja) 足場の配置中にけるバルーン膨張速度の制御
CN105120806A (zh) 带有多褶球囊的聚合物支架
US12076513B2 (en) Methods of fabricating a heart valve delivery catheter
WO2019084951A1 (zh) 一种非植入式球囊导管的高强度约束支架及应用该约束支架的血管扩张装置
HK1187232B (en) Stent crimping methods
HK1200306A1 (zh) 具有非線性軸向支柱的約束結構