1、Designation: F2394 07 (Reapproved 2013)Standard Guide forMeasuring Securement of Balloon Expandable VascularStent Mounted on Delivery System1This standard is issued under the fixed designation F2394; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase 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 provides guidance for the design and devel-opment of pre-test treatments, test
3、s, and test endpoints tomeasure stent securement of pre-mounted, unsheathed,balloon-expandable stent delivery systems. This guide is in-tended to aid investigators in the design, development, and invitro characterization of pre-mounted, unsheathed, balloon-expandable stent delivery systems.1.2 This
4、guide covers the laboratory determination of theshear force required to displace or dislodge a balloon-expandable endovascular stent mounted on a delivery system.The guide proposes a set of options to consider when testingstent securement. The options cover pre-test treatments, pos-sible stent secur
5、ement tests, and relevant test endpoints. Anexample test apparatus is given in 7.1.1.3 This guide covers in vitro bench testing characterizationonly. Measured levels of securement and product design/process differentiation may be particularly influenced by selec-tions of pre-test treatments, securem
6、ent test type (for example,stent gripping method), and test endpoint. In vivo characteris-tics may also differ from in vitro results.1.4 This guide does not cover all possible pre-testtreatments, stent securement tests, or test endpoints. It isintended to provide a starting point from which to selec
7、t andinvestigate securement test options.1.5 This guide does not specify a method for mounting thestent onto the delivery system.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; theref
8、ore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard
9、 to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2E1169 Practice for Conducting Ruggedness TestsE1488 Guide for Statistical Procedures to Use in Developingand Applying Test Method
10、s2.2 Other Documents:ISO 10555-1 Sterile Sterile Sterile, Single-use IntravascularCathetersPart 1: General Requirements3Quality System Regulation, Part VII Dept. Health and Hu-man Services, Food and Drug Administration, 21 CFRPart 820 Medical Devices; Current Good ManufacturingPractice; Final Rule.
11、Federal Register, October 7, 19964EN 14299 Non Active Surgical ImplantsParticular Re-quirements for Cardiac and Vascular ImplantsSpecificRequirements For Arterial Stents, May 20045CDRH Guidance, Non-Clinical Tests and RecommendedLabeling for Intravascular Stents and Associated DeliverySystems, Janua
12、ry 13, 20056MAUDE Database73. Terminology3.1 Definitions:3.1.1 balloon expandable stent, na stent that is expandedat the treatment site by a balloon catheter. The stent material is1This guide is under the jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the dire
13、ct responsibility of SubcommitteeF04.30 on Cardiovascular Standards.Current edition approved March 1, 2013. Published March 2013. Originallyapproved in 2004. Last previous edition approved in 2007 as F2394 07. DOI:10.1520/F2394-07R13.2For referenced ASTM standards, visit the ASTM website, www.astm.o
14、rg, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.
15、4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5Available from British Standards Institute (BSI), 389 Chiswick High Rd.,London W4 4AL, U.K., http:/www.bsi-.6Available from Food and Dru
16、g Administration (FDA), 5600 Fishers Ln.,Rockville, MD 20857,. Http:/www.fda.gov/cdrh/ode/guidance/1545.pdf.7Http:/www.fda.gov/cdrh/maude.html.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1plastically deformed by the balloon expansi
17、on such that thestent remains expanded after deflation of the balloon.3.1.2 crimp, vto secure the stent on the delivery system byradially compressing and plastically deforming the stent ontothe balloon.3.1.3 delivery system, na system similar to a balloondilatation catheter that is used to deliver a
18、nd deploy a stent atthe target site and then removed.3.1.4 displacement force, critical distance peak, na stentsecurement test endpoint characterizing the maximum forcerequired to displace the stent with respect to the balloon acritical distance. This critical distance is the minimum of thefollowing
19、 two distances. The first is the distance at which theundamaged stent could overhang the balloon body resulting ina clinically significant, incomplete end deployment. The sec-ond is the length (distance) of stent compression or bucklingthat could result in a clinically significant incomplete deploy-
20、ment of the stent against the vessel walls. (See Fig. X2.1.)3.1.5 displacement force, initial, na stent securement testendpoint characterizing the initial force required to displace thestent with respect to the balloon such that the displacement isa non-recoverable movement (see 3.1.15). (See Fig. X
21、2.1.)3.1.6 displacement force, initial peak, na stent securementtest endpoint characterizing the first peak in force that occursduring or after stent displacement with respect to the balloon.(See Fig. X2.1.)3.1.7 dislodgment force, peak, na stent securement testendpoint characterizing the peak or ma
22、ximum force required tocompletely dislodge the stent from the delivery system balloon.During a test, this force will occur after or coincide with theinitial displacement force. (See Fig. X2.1.)3.1.8 end flaring, na distal or proximal outward conicalopening of the diameter of the stent on the balloon
23、. End flaringis a contributing factor to the probability that the stent maybecome caught during withdrawal into a guide catheter whiletracking through a lesion.3.1.9 failure mode effect analysis (FMEA), nan analyticalapproach to methodically determine and address all possibleproduct failure modes, t
24、heir associated causes, and theircriticality. Used to evaluate designs, prioritize testing, andtrack risk reducing improvements to the product.3.1.10 gauge length, nthe initial unstressed length ofcatheter tubing between the proximal end of the stent to thegrips which engage the catheter tubing.3.1.
25、11 grips, na means of applying force to the stent andballoon catheter to displace or dislodge the stent relative to theballoon. In particular, grips refer to the end of a device whichmakes the contact with the stent. Typical grips used to applyforce to the stent include shims (as used in Figs. X2.5-
26、X2.8);tape which sticks to the stent but not the balloon; an iris whichcan be narrowed down to allow the balloon to slip by but notthe stent; or nubs which contact the stent but not the balloon.3.1.12 guide catheter, na tube designed to transport theguide-wire and the stent delivery system into the
27、target vessel.3.1.13 guide-wire, na wire designed to aid in balloon,ultrasound, atherectomy, or stent placement during endovascu-lar procedures.3.1.14 mandrel, na wire that may be used as an alternativeto the intended guide-wire to provide support for the catheterguide-wire lumen for some test proce
28、dures.3.1.15 non-recoverable movement, na displacement of thestent relative to the balloon such that if the shearing force wasreduced to zero, the stent would remain displaced in thedirection of the shearing force relative to the initial placementon the balloon. The force at which non-recoverable mo
29、vementbegins is defined as the initial displacement force (see defini-tion above).3.1.16 pre-test treatment, na treatment of the stent deliv-ery system prior to the evaluation of securement that simulatespreparatory, environmental, mechanical or other conditionsthat may be encountered prior to or du
30、ring clinical use of thedevice. Examples include subjecting the devices to elevatedshipping temperature/humidity, catheter preparation per useinstructions, pre-soaking, bending treatments, tracking treat-ments (tracking fixture, see definition below) and trackingthrough lesion treatments (lesion fix
31、ture, see definition below).3.1.17 pre-test treatment tracking fixture, na pre-test treat-ment fixture used to simulate an anatomical vasculature. Use ofthe fixture with a guide catheter, a guide-wire and the stent-balloon catheter delivery system is intended to simulate thebending and frictional fo
32、rces of tracking the device to thelesion site that may be encountered in the clinical setting. Seethe engineering diagrams in the Appendix. Note that theseengineering diagrams simulate vessels with a moderatelydifficult degree of coronary tortuousity but do not includesimulated lesions.3.1.18 pre-te
33、st treatment lesion fixture, na pre-test treat-ment fixture used to simulate an anatomical vasculature andlesion. Use of the fixture with a guide catheter, a guide-wire,and the stent-balloon catheter delivery system is intended tosimulate the bending, frictional and mechanical resistanceforces of tr
34、acking the device across the lesion site that may beencountered in the clinical setting.3.1.19 securement test, guide-type, na stent securementtest that is similar to the clinical scenario of pulling anundeployed stent delivery system back into a guide catheter,arterial sheath or hemostasis valve. E
35、xamples include guides,rings, or shims ideally designed to engage the stent end or bodybut not the catheter balloon. The shim securement test, de-scribed in Section 7, uses complementary thin, rigid plates withrounded “V” notches that are sized to circumferentially engagethe stent end but not the ca
36、theter balloon. See the engineeringdiagrams in the Appendix.3.1.20 securement test, lesion-type, na stent securementtest that is similar to the clinical scenario of pushing or pullingan undeployed stent delivery system through or around afibrous or calcified lesion. Examples include tape, nubs,protr
37、usions or sandpaper ideally designed to engage the stentend or body but not the catheter balloon.F2394 07 (2013)24. Significance and Use4.1 The securement of the endovascular stent on the balloonis a critical parameter to ensure that the stent is safely deliveredto or from the treatment site.4.2 Thi
38、s guide is intended for use by researchers andmanufacturers for the development and selection of pre-testtreatments, tests and test endpoints to measure stent secure-ment (displacement distances and dislodgment forces).4.3 This guide may be used to investigate which practicalcombinations of in vitro
39、 tests best characterize clinical sce-narios.4.4 This guide should be used with discretion in choosingsecurement tests and evaluating results due to the myriadpossible combinations of clinical conditions, failure modes,and stent delivery system designs.4.5 This guide may be of use for developing a t
40、est formeeting parts 2 and 3 of the requirements of EN 14299,Section 7.3.4.4 on Trackability.4.6 This guide may be of use for developing a test to meetsection VII-C-8 of CDRH Guidance document.5. Clinical Scenarios5.1 There are two failure modesthe stent is dislodgedfrom the catheter or the stent is
41、 displaced or deformed on thecatheter such that balloon inflation delivery would not producean acceptable stent shape at the proper location. Based onreported clinical incidents, there are three causes for these twotypes of failures:5.1.1 Displacement or dislodgment of the stent while at-tempting to
42、 track through or position in tortuous bends, fibrousor calcified lesions, or previously implanted stents, or combi-nation thereof.5.1.2 Displacement or dislodgment of the stent on with-drawal of the undeployed stent delivery system back into theguide catheter, introducer sheath, or hemostasis valve
43、. Thisfailure type is usually associated with failure to cross tortuousbends, fibrous or calcified lesions, or previously implantedstents, or combination thereof. It is sometimes associated withless-than-ideal seating or angled placement of the guidecatheter tip in the ostium of the vessel.5.1.3 Dis
44、placement or dislodgement of the stent due toimproper catheter preparation including mishandling or partialballoon inflation during preparation. This has been identified ina few cases where the loose, displaced, or dislodged stent wasobserved prior to use but may conceivably play a role in asmall pe
45、rcentage of cases where dislodgment occurs in pa-tients.6. Test Method Considerations6.1 FlowchartSee Fig. 1.6.2 Development and Evaluation of Securement Tests:6.2.1 Securement test development and selection is ideallybegun through the initial use of a battery of tests measuring avariety of failure
46、modes. These test methods may vary from asimple intuitive tactile impression of the securement forcesthrough manipulation to clinically modeled situations withguide catheters and stenosis models to in vivo animal studieswith representative anatomy and physician handling. From asafety-risk perspectiv
47、e, consider how securement challengesmay occur in clinical situations, what may result from loss ofsecurement, what the severity of the outcome is to the patient,what the frequency of these situations are, and then how to testto detect these occurrences. Factors to consider in evaluatingsecurement t
48、ests include the following:6.2.1.1 Review of the MAUDE database for reported prob-lems with comparable devices.6.2.1.2 Physician surveys for clinical relevance and prob-lems with comparable devices.6.2.1.3 Mechanical understanding of the tests clinical rel-evance and limitations.6.2.1.4 Mechanical a
49、nd statistical understanding of the testreproducibility limitations due to device variation, pre-testtreatments, various grips, and test conditions.6.2.1.5 Ability to set accept/reject criteria by physicianevaluation, by historical comparisons, or by other rationalmeans.6.2.2 The final securement test(s) selected must ultimatelysatisfy internal manufacturer quality standards. These stan-dards may include clinical relevance, FMEA analysis, statisti-cal assurance of characteristics, and challenge assurance ofcharacteristics.6.2.3 The final secu
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