1、Designation: F2081 06 (Reapproved 2013)Standard Guide forCharacterization and Presentation of the DimensionalAttributes of Vascular Stents1This standard is issued under the fixed designation F2081; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 dime
3、nsional attributesof 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 characteri
4、s-tics of stents. 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 charact
5、eristics may beslightly 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, althou
6、gh the application 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. Likew
7、ise, thisguide 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 gui
8、de does not include 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 a
9、nd ISO 10555-4.1.6 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-c
10、onformancewith the standard.1.6.1 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
11、 selection of devices by clinicalusers, 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,Gen
12、eral Requirements2ISO 10555-4, 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
13、by the balloon expansion such 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.
14、1.3 crimp, vto secure the stent 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 t
15、he delivery system.1This guide is under the jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devicesand is the direct responsibility of SubcommitteeF04.30 on Cardiovascular Standards.Current edition approved March 1, 2013. Published March 2013. Originallyapproved in 2001. Last
16、 previous edition approved in 2006 as F2081 06. DOI:10.1520/F2081-06R13.2Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. U
17、nited States13.1.5 delivery system, na system that is used to deliver anddeploy 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 th
18、estent unless otherwise noted.3.1.7 diameter, labeled, 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
19、 solid area, nthat percentage of the projectedcylindrical side surface area ( 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
20、 delivery system.3.1.10 self-expanding stent, na 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 con
21、struction or thestructural geometry, or both.3.1.11 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 b
22、etween the undeployed mounted condition and theexpanded labeled-diameter condition.3.1.13 stent, vascular, na synthetic tubular structure that ispermanently implanted in the native or grafted vasculature andthat is intended to provide mechanical radial support toenhance vessel patency. For the purpo
23、ses of this guide, a stentis metallic and not covered 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 th
24、at is not crimped on adelivery system as supplied 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 ofm
25、aintaining vessel patency. The dimensional attributes 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 the
26、se devices, alongwith recommendations for consistent 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 cha
27、racter-istics. It may have use in the regulation 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, bec
28、ause of the myriad patient andmedical factors that 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.
29、Classification5.1 Stents may be classified by the 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 measu
30、ring the attributes described in this guideshould 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 thatsteriliza
31、tion has no affect on the attribute being assessed.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 mu
32、st beappropriately selected for each design and attribute. 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 fina
33、l deployeddiameter for stents made from shape memory 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
34、number of specimens evaluated for each diameterfor 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 bedeplo
35、yed over a broad range of diameters by use on differentsize 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 diame
36、ter, reported inmillimetres to the nearest 0.1 mm, after balloon deflation (forballoon-expandable stents).F2081 06 (2013)27.1.1 MeasurementThe outside diameter of deployedstents should be measured by noncontacting instruments (pro-file projector, laser micrometer, and so forth) with a resolutionof 0
37、.05 mm or better. Inside diameter can then be calculated bysubtracting 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, forexampl
38、e, 3.0 mm or 3.5 mm, and must be clearly identified asinside or outside diameter (ID or OD). ID is preferred. Thelabeled diameter is usually rounded to the nearest 0.25 or 0.5mm.7.1.3 Stent System ComplianceFor balloon-expandablestents, a table or graph of inflation pressure versus expandeddiameter
39、should be developed and included in the labeling. Aminimum 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
40、 stents at that pressure. The inflation pressureshould be 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
41、 to its labeleddiameter. Uniformity of expansion is not intended 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 c
42、lose to each end) ateach of two circumferential orientations 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 mounte
43、d or expandedstents should be measured by noncontacting instruments (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
44、of ten replicatedevices and should be reported to the nearest 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)
45、 LengthThis attribute has nosignificance in and of itself. 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 percentag
46、echange in length between the undeployed mounted conditionand 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
47、 delivery system in accordance with the instruc-tions for 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
48、instrument should be either noncontacting (opti-cal profilometer, 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 Bri
49、dge Thickness:7.4.1 MeasurementStrut and bridge thicknesses 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 micrometers. 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 b
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