1、Designation: F 2394 07Standard Guide forMeasuring Securement of Balloon Expandable VascularStent Mounted on Delivery System1This standard is issued under the fixed designation F 2394; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the 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 provides guidance for the design and devel-opment of pre-test treatments, tests, and test end
3、points 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 guide covers th
4、e 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 securement tests, an
5、d 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, securement test type (
6、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-test treat-ments, stent securement tests, or test endpoints. It is intended toprovide a starting point from which to select and investi
7、gatesecurement test options.1.5 This guide does not specify a method for mounting thestent onto the delivery system.1.6 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 to establish appro-priate
8、 safety and health practices and determine the applica-bility of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2E 1169 Guide for Conducting Ruggedness TestsE 1488 Guide for Statistical Procedures to Use in Develop-ing and Applying Test Methods2.2 Other Documents:ISO
9、10555-1 Sterile Sterile Sterile, Single-use IntravascularCathetersPart 1: General Requirements3Quality System Regulation, Part VII Dept. Health andHuman Services, Food and Drug Administration, 21 CFRPart 820 Medical Devices; Current Good ManufacturingPractice; Final Rule. Federal Register, October 7
10、, 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, January 13, 20056MAUDE Database7
11、3. Terminology3.1 Definitions:3.1.1 balloon expandable stent, na stent that is expandedat the treatment site by a balloon catheter. The stent material isplastically deformed by the balloon expansion such that thestent remains expanded after deflation of the balloon.1This guide is under the jurisdict
12、ion of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.30 on Cardiovascular Standards.Current edition approved July 15, 2007. Published August 2007. Originallyapproved in 2004. Last previous edition approved in 2004 as F 2394 04.2Fo
13、r referenced ASTM standards, visit the ASTM website, www.astm.org, 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
14、 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.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.,L
15、ondon W4 4AL, U.K., http:/www.bsi-.6Available from Food and Drug Administration (FDA), 5600 Fishers Ln.,Rockville, MD 20857,. Http:/www.fda.gov/cdrh/ode/guidance/1545.pdf.7Http:/www.fda.gov/cdrh/maude.html.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428
16、-2959, United States.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 and deploy a stent atthe target site and then remo
17、ved.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 two distances. The first is the distance at whic
18、h 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-ment of the stent against the vessel walls. (See
19、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. X2.1.)3.1.6 displacement force, initial peak, na s
20、tent secure-ment test endpoint characterizing the first peak in force thatoccurs during or after stent displacement with respect to theballoon. (See Fig. X2.1.)3.1.7 dislodgment force, peak, na stent securement testendpoint characterizing the peak or maximum force required tocompletely dislodge the
21、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. End flaringis a contributing factor to the pr
22、obability 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, their associated causes, and theircriticality. U
23、sed 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.3.1.11 grips, na means of applying force to the ste
24、nt 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-X2.8);tape which sticks to the stent but not th
25、e 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 target vessel.3.1.13 guide-wire, na wire design
26、ed 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 procedures.3.1.15 non-recoverable movement, na displ
27、acement 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 movementbegins is defined as the initial displace
28、ment 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 during clinical use of thedevice. Examples includ
29、e 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 fixture, see definition below).3.1.17 pre-test tre
30、atment tracking fixture, na pre-testtreatment fixture used to simulate an anatomical vasculature.Use of the fixture with a guide catheter, a guide-wire and thestent-balloon catheter delivery system is intended to simulatethe bending and frictional forces of tracking the device to thelesion site that
31、 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-test treatment lesion fixture, na pre-test treat-men
32、t 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 tracking the device across the lesion site that may
33、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. Examples include guides,rings, or shims ideally des
34、igned 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 catheter balloon. See the engineeringdiagrams in the
35、 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,protrusions or sandpaper ideally designed to engage the
36、 stentend or body but not the catheter balloon.4. 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 This guide is intended for use by researchers andmanufacturers for th
37、e development and selection of pre-testtreatments, tests and test endpoints to measure stent secure-ment (displacement distances and dislodgment forces).F23940724.3 This guide may be used to investigate which practicalcombinations of in vitro tests best characterize clinical sce-narios.4.4 This guid
38、e 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 test formeeting parts 2 and 3 of the requirements of EN 142
39、99,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 displaced or deformed on thecatheter such that balloon in
40、flation 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 track through or position in tortuous bends, fibrousor ca
41、lcified 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. Thisfailure type is usually associated with failure to c
42、ross 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 Displacement or dislodgement of the stent due toimproper cath
43、eter 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 percentage of cases where dislodgment occurs in pa-tients.6.
44、 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 modes. These test methods may vary from asimple intuitive
45、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 perspective, consider how securement challengesmay occur in clinical
46、 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 tests include the following:6.2.1.1 Review of the MAUDE dat
47、abase 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 and statistical understanding of the testreproducibility li
48、mitations 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 manufacture
49、r 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 securement test(s) must also satisfy externalregulatory body standards. For example, the FDAQSR 21 CFRPart 820, Oct. 7, 1996 states that each test used in the processof design and manufacturing of finished devices “is suitable forits intended purposes and is capable of producing validresults.” For the statistical capability evaluation, Guide E 1488is very helpfu
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