1、Designation: F 2081 06Standard Guide forCharacterization and Presentation of the DimensionalAttributes of Vascular Stents1This standard is issued under the fixed designation F 2081; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the identification of and recom-mended measurement methods for those dimensional attribu
3、tesof vascular stents that are deemed relevant to successfulclinical performance. The delivery system packaged with andlabeled specifically for use during the placement of the stent isalso included within the scope of this guide.1.2 This guide addresses only the dimensional characteris-tics of stent
4、s. Material property and stent functional character-istics are not addressed herein. All dimensional characteristicsdescribed in this guide refer to in vitro (“bench-top”) charac-terization. Because of variable patient factors, for example,vessel compliance, the actual in vivo characteristics may be
5、slightly different.1.3 This guide includes recommendations generally appli-cable to balloon-expandable and self-expanding stents fabri-cated from metals and metal alloys. It does not specificallyaddress any attributes unique to coated stents or polymeric orbiodegradable stents, although the applicat
6、ion of this guide tothose products is not precluded.1.4 While they are not specifically included within the scopeof this guide, stents indicated for placement in nonvascularlocations, such as the esophagus or bile duct, also might becharacterized by the methods contained herein. Likewise, thisguide
7、does not include recommendations for endovasculargrafts (“stent-grafts”) or other conduit devices commonly usedto treat aneurysmal disease or peripheral vessel trauma or toprovide vascular access, although some information includedherein may be applicable to those devices.1.5 This guide does not inc
8、lude recommendations for bal-loon catheters sold as stand-alone angioplasty catheters, eventhough some of those catheters may be used for the delivery ofunmounted stents supplied without a delivery system. Require-ments for angioplasty catheters are contained in standards ISO10555-1 and ISO 10555-4.
9、1.6 The units of measurements used throughout this guidereflect the hybrid system in common clinical use in the UnitedStates as of the time of the original approval of this guide.Since a primary purpose of this guide is to promote uniformityof labeling to facilitate the selection of devices by clini
10、calusers, the units most preferred by users were selected for thisguide. Where those units are not SI units, or derivativesthereof, SI units are provided in parentheses.2. Referenced Documents2.1 ISO Standards:ISO 10555-1, Sterile, Single-Use Intravascular Catheters,General Requirements2ISO 10555-4,
11、 Sterile, Single-Use Intravascular CathetersBalloon Dilation Catheters23. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 balloon-expandable stent, na stent that is expandedat the treatment site by a balloon catheter. The stent is alteredpermanently by the balloon expansion such
12、that the stentremains expanded after deflation of the balloon.3.1.2 bridge, na connecting element between the radialsupport aspects of a stent. A bridge may have unique designfeatures, as compared to a strut, to enhance longitudinalflexibility and minimize shortening.3.1.3 crimp, vto secure the sten
13、t on the delivery system bycompressing the stent onto the balloon. Stents sold unmountedmust be crimped manually by the clinical staff before use.3.1.4 crossing profile, na linear measure of the maximumbreadth of the stent/delivery system over the distal-most regionof the delivery system.3.1.5 deliv
14、ery system, na system that is used to deliverand deploy a stent at the target site. A delivery system may besimilar to a balloon dilatation catheter; a delivery system for aself-expanding stent might not have a balloon.3.1.6 diameter, nrefers to the inside diameter (ID) of thestent unless otherwise
15、noted.1This guide is under the jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.30 on Cardiovascular Devices.Current edition approved Sept. 1, 2006. Published September 2006. Originallyapproved in 2001. Last previous
16、edition approved in 2001 as F 2081 01.2Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 diameter, labe
17、led, nsingle value representation ofintended-use diameters, typically rounded to nearest 0.25 or0.5 mm. The labeled diameter is within the range recom-mended in the Instructions for Use (IFU) for that particularstent and delivery system.3.1.8 percent solid area, nthat percentage of the projectedcyli
18、ndrical side surface area (p times outside diameter timeslength at labeled diameter) that is covered by stent material,when the stent is expanded to its labeled diameter.3.1.9 premounted stent, na stent supplied by a manufac-turer already mounted on a delivery system.3.1.10 self-expanding stent, na
19、stent that expands withoutextrinsic force or pressure, to a size and shape close to thedesired final size and shape, when released from the deliverysystem. The self-expanding nature of some stents is a designfeature resulting from the materials of construction or thestructural geometry, or both.3.1.
20、11 sheath, na movable cover that constrains a self-expanding stent on the delivery system until its desired releaseor protects a balloon-expandable stent during delivery beforedeployment.3.1.12 shortening/lengthening, nthe percentage change inlength between the undeployed mounted condition and theex
21、panded labeled-diameter condition.3.1.13 stent, vascular, na synthetic tubular structure thatis permanently implanted in the native or grafted vasculatureand that is intended to provide mechanical radial support toenhance vessel patency. For the purposes of this guide, a stentis metallic and not cov
22、ered by synthetic textile or tissue graftmaterial.3.1.14 strut, nthe smallest individual element of the radialsupport aspect of a stent that has a solid cross section in boththe radial and circumferential directions.3.1.15 unmounted stent, na stent that is not crimped on adelivery system as supplied
23、 by the manufacturer. Before use,the clinical staff must manually crimp unmounted stents onto adelivery device.4. Significance and Use4.1 Vascular stents are intended for permanent implant inthe human vasculature (native or graft) for the purposes ofmaintaining vessel patency. The dimensional attrib
24、utes ofvascular stents are critical parameters that aid clinicians in theselection of devices for individual patients. This guide containsa listing of those dimensional attributes that are directly relatedto the clinical utility and performance of these devices, alongwith recommendations for consist
25、ent methods of measuringthese attributes and presenting the information for use inclinical decision making. This guide can be used by themanufacturers and researchers of stents to provide consistencyof measurement and labeling of these dimensional character-istics. It may have use in the regulation
26、of these devices byappropriate authorities.4.2 The dimensional attributes included in this guide arethose that are deemed related to or possibly predictive ofsuccessful clinical performance of the stent, based on priorclinical experience; however, because of the myriad patient andmedical factors tha
27、t influence the clinical outcome of anyindividual treatment, conformance of a stent and deliverysystem with the recommendations in this guide should not beinterpreted as a guarantee of clinical success in any individualpatient or group of patients.5. Classification5.1 Stents may be classified by the
28、 following characteristics,as defined in Section 3.5.1.1 MountingPremounted or unmounted.5.1.2 ExpansionBalloon expandable or self-expanding.6. Test Devices and General Procedures6.1 Unless otherwise justified, all samples selected fortesting or measuring the attributes described in this guideshould
29、 be taken from finished, clinical-quality product. Cos-metic rejects or other nonclinical samples may be used if thecause for rejection is not related to the attribute being assessed.Sterilization can be omitted if it can be demonstrated thatsterilization has no affect on the attribute being assesse
30、d.6.2 When specimen preparation (for example, manualcrimping onto a delivery system, balloon expansion), is re-quired before testing, this should be done in accordance withthe Instructions for Use (IFU).6.3 The preconditioning and test environments must beappropriately selected for each design and a
31、ttribute. Tempera-ture and fluid immersion may have a significant effect on someattributes but a negligible affect on others. For example, fluidsorption may swell catheters and affect the measurement ofcrossing profile. Temperature may affect the final deployeddiameter for stents made from shape mem
32、ory materials. Formeasurements for which deployment, or measurement, or both,is to be made in a controlled environment, the stent or deliverysystem, or both, should be immersed in a water bath main-tained at 37 6 2C and allowed to equilibrate.6.4 The number of specimens evaluated for each diameterfo
33、r each stent design should be sufficient to meet the samplingrequirements for the desired labeling. In general, a minimum often replicate test devices of each size to be measured or testedis recommended. If a single stent design is intended to bedeployed over a broad range of diameters by use on dif
34、ferentsize delivery systems, the dimensional attributes should beevaluated for each stent/delivery system combination.7. Dimensions and Measurement Methods7.1 Deployed DiameterUnless otherwise specified, alldeployed diameters refer to the inside diameter, reported inmillimetres to the nearest 0.1 mm
35、, after balloon deflation (forballoon-expandable stents).7.1.1 MeasurementThe outside diameter of deployedstents should be measured by noncontacting instruments (pro-file projector, laser micrometer, and so forth) with a resolutionof 0.05 mm or better. Inside diameter can then be calculated bysubtra
36、cting twice the wall thickness (7.4). Alternatively, theinside diameter can be measured by calibrated gauges.7.1.2 Labeled DiameterThe labeled diameter is that usedto identify the typical deployed size of a particular device, forexample, 3.0 mm or 3.5 mm, and must be clearly identified asinside or o
37、utside diameter (ID or OD). ID is preferred. Thelabeled diameter is usually rounded to the nearest 0.25 or 0.5mm.F20810627.1.3 Stent System ComplianceFor balloon-expandablestents, a table or graph of inflation pressure versus expandeddiameter should be developed and included in the labeling. Aminimu
38、m of ten replicate devices should be measured at eachstent size at each labeled inflation pressure. The expanded stentinside diameter at each inflation pressure, rounded to thenearest 0.05 mm, should be the mean of all measurementstaken on all stents at that pressure. The inflation pressureshould be
39、 expressed in atmospheres. This attribute does notapply to self-expanding stents.7.1.4 Uniformity of ExpansionThe uniformity of expan-sion refers to the difference between the largest and smallestdiameter measurement on a single stent deployed to its labeleddiameter. Uniformity of expansion is not i
40、ntended to charac-terize deliberate deviations from cylindricity, such as taperedconstruction, end flares, antimigration barbs, and so forth.Measurements for the uniformity of expansion should be takenat three axial locations (mid-length and close to each end) ateach of two circumferential orientati
41、ons at about 90 separa-tion. The uniformity of expansion reflects both the deviationfrom circularity of the stent cross section and unintendeddifferences in diameter along the stent length.7.2 Stent Length:7.2.1 MeasurementThe length of mounted or expandedstents should be measured by noncontacting i
42、nstruments (pro-file projection, laser micrometer, and so forth) with a resolutionof 0.1 mm or better. Measurements should be taken on eachstent in the mounted state and at the labeled diameter. Lengthsshould reflect measurements on a minimum of ten replicatedevices and should be reported to the nea
43、rest 1 mm.7.2.2 Labeled Expanded LengthThe labeled expandedlength is that used to identify the typical size of a particulardevice, for example, 20 mm. The labeled expanded length isusually rounded to the nearest 1 mm.7.2.3 Mounted (Undeployed) LengthThis attribute has nosignificance in and of itself
44、. It provides a baseline for thedetermination of shortening/lengthening. Direct measurementof the mounted length may not be possible for sheathedsystems. Other appropriate methods may be used.7.2.4 Shortening/LengtheningRefers to the percentagechange in length between the undeployed mounted conditio
45、nand the expanded labeled-diameter condition. Shortening/lengthening should be reported as a percentage of the mounted(undeployed) length to the nearest 1 %.7.3 Crossing Profile:7.3.1 MeasurementWith the stent premounted or hand-crimped on the delivery system in accordance with the instruc-tions for
46、 use, and the sheath (if any) in place, measure themaximum diameter over the length from the proximal end ofthe mounted stent to the distal tip of the delivery system. Aminimum of ten replicate test articles should be measured. Themeasurement instrument should be either noncontacting (opti-cal profi
47、lometer, laser micrometer, and so forth) or a ring/holegage, and should have a resolution of 0.001 in. (0.025 mm) orbetter. The crossing profile should be reported as the meanmeasurement result to the nearest 0.001 in. (0.025 mm).7.4 Strut and Bridge Thickness:7.4.1 MeasurementStrut and bridge thick
48、nesses of theexpanded stent may be measured by subtraction of measuredinside and outside diameters, by direct measurement withspecialized instrumentation, by scanning electron microscopy,by profile projection, or destructively by cutting, or flattening,or both, a stent for access by standard microme
49、ters. Sincepolishing or other manufacturing processes may change strutand bridge thickness from that of raw material, measurementsfrom other-than-finished product should be used judiciously.Strut and bridge thickness should be measured at the stentmid-length and near each end, at two circumferential locationsat each axial location. If strut and bridge thicknesses aresystematically different by design, they should be measuredand reported separately. Strut and bridge thickness should bereported in inches to the nearest 0.0005 in. (0.013 mm).7.5 Percent Soli
