ASTM F2079-09
(Test Method)Standard Test Method for Measuring Intrinsic Elastic Recoil of Balloon-Expandable Stents
Standard Test Method for Measuring Intrinsic Elastic Recoil of Balloon-Expandable Stents
SIGNIFICANCE AND USE
Minimal stent recoil is a desirable feature of a stent because it minimizes the maximum diameter to which a stent must be expanded to achieve its final relaxed diameter. A stent having a high recoil must be expanded to a greater diameter to achieve its final relaxed diameter than a stent having low recoil. Practically, excessive expansion of the vessel into which the stent is to be implanted may cause tissue damage resulting in a poor immediate result or poor long-term outcome. Stent recoil is affected by intrinsic properties of the material used to construct the stent and the specific geometric design of the stent; therefore, measuring stent recoil is an essential part of evaluating the design.
SCOPE
1.1 The purpose of this test method is to quantify the percentage by which the diameter of a stent decreases from its expanded diameter while still on the delivery balloon to its relaxed diameter after deflating the balloon. This test method is appropriate for stents manufactured from a material that is plastically deformed when the stent's diameter is increased from its predeployed size to its postdeployed size by mechanical means. This test method may be performed in air at room temperature unless there is a known temperature dependence of the material, in which case, the temperature at which the test is conducted shall be stated in the report.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: F2079 − 09
StandardTest Method for
Measuring Intrinsic Elastic Recoil of Balloon-Expandable
1
Stents
This standard is issued under the fixed designation F2079; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope The outer diameter of the stent is measured in at least three
axial locations while the stent is still on the inflated delivery
1.1 The purpose of this test method is to quantify the
balloon.At each axial location, measurements are taken in two
percentage by which the diameter of a stent decreases from its
approximately orthogonal rotational positions. The balloon is
expanded diameter while still on the delivery balloon to its
deflated and the outer diameter of the stent is remeasured in the
relaxed diameter after deflating the balloon.This test method is
same positions at approximately the same locations.
appropriate for stents manufactured from a material that is
plastically deformed when the stent’s diameter is increased
4. Significance and Use
from its predeployed size to its postdeployed size by mechani-
cal means. This test method may be performed in air at room
4.1 Minimal stent recoil is a desirable feature of a stent
temperatureunlessthereisaknowntemperaturedependenceof
because it minimizes the maximum diameter to which a stent
the material, in which case, the temperature at which the test is
must be expanded to achieve its final relaxed diameter.Astent
conducted shall be stated in the report.
having a high recoil must be expanded to a greater diameter to
achieve its final relaxed diameter than a stent having low
1.2 The values stated in SI units are to be regarded as
recoil. Practically, excessive expansion of the vessel into which
standard. No other units of measurement are included in this
the stent is to be implanted may cause tissue damage resulting
standard.
in a poor immediate result or poor long-term outcome. Stent
1.3 This standard does not purport to address all of the
recoil is affected by intrinsic properties of the material used to
safety concerns, if any, associated with its use. It is the
construct the stent and the specific geometric design of the
responsibility of the user of this standard to establish appro-
stent; therefore, measuring stent recoil is an essential part of
priate safety and health practices and determine the applica-
evaluating the design.
bility of regulatory limitations prior to use.
5. Apparatus
2. Terminology
5.1 Ameans to inflate with noncompressible fluid, typically
2.1 Definitions:
water, the delivery balloon on which the stent is mounted. The
2.1.1 labeled diameter, n—the nominal deployed size of a
means used must be capable of achieving the pressure required
stent as indicated on its manufacturer’s label.
to maintain the expanded diameter of the stent until it can be
2.1.2 stent recoil, n—the amount, expressed as a percentage,
measured and may include a device to monitor pressure.
by which the diameter of a stent changes from the expanded
diameter measured with the stent on the inflated delivery
5.2 A means to measure the outer diameter of the stent
balloon to the final value measured after deflating the balloon.
without deforming the stent. Typically, a calibrated optical
system, which does not require contact with the stent, is used.
3. Summary of Test Method
The resolution of the measurement system shall be 0.01 mm or
3.1 A sample device representative of product that will be better. The accuracy of the system shall be 2 % of reading or
marketed is either premounted or mounted on the delivery better.
balloon at the time of use. The delivery balloon is inflated to
the nominal expansion pressure indicated for the labeled stent. 6. Sampling, Test Specimens, and Test Units
6.1 Unless otherwise justified, all samples selected for
1
testing should be taken from fully processed, clinical quality
This test method is under the jurisdiction ofASTM Committee F04 on Medical
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
product. It is not required that these devices undergo terminal
F04.30 on Cardiovascular Standards.
sterilization.Cosmeticrejectsorothernonclinicalsamplesmay
Current edition approved Aug. 1, 2009. Published August 2009. Originally
be used if the cause for rejection has been shown not to affect
approved in 2001. Last previous edition approved in 2008 as F2079 – 02(2008).
DOI: 10.1520/F2079-09. stent recoil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F2079 − 09
6.2
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F2079–02 (Reapproved 2008) Designation: F 2079 – 09
Standard Test Method for
Measuring Intrinsic Elastic Recoil of Balloon-Expandable
1
Stents
This standard is issued under the fixed designation F 2079; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 The purpose of this test method is to quantify the percentage by which the diameter of a stent decreases from its expanded
diameter while still on the delivery balloon to its relaxed diameter after deflating the balloon. This test method is appropriate for
stents manufactured from a material that is plastically deformed when the stent’s diameter is increased from its predeployed size
to its postdeployed size by mechanical means. This test method may be performed in air at room temperature unless there is a
known temperature dependence of the material, in which case, the temperature at which the test is conducted shall be stated in the
report.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Terminology
2.1 Definitions:
2.1.1 labeled diameter, n—the nominal deployed size of a stent as indicated on its manufacturer’s label.
2.1.2 stent recoil, n—the amount, expressed as a percentage, by which the diameter of a stent changes from the expanded
diameter measured with the stent on the inflated delivery balloon to the final value measured after deflating the balloon.
3. Summary of Test Method
3.1 A sample device representative of product that will be marketed is either premounted or mounted on the delivery balloon
at the time of use. The delivery balloon is inflated to the nominal expansion pressure indicated for the labeled stent. The outer
diameter of the stent is measured in two approximately orthogonal rotational positionsat least three axial locations while the stent
is still on the inflated delivery balloon.At each axial location, measurements are taken in two approximately orthogonal rotational
positions.The balloon is deflated and the outer diameter of the stent is remeasured in the same positions at approximately the same
locations.
4. Significance and Use
4.1 Minimal stent recoil is a desirable feature of a stent because it minimizes the maximum diameter to which a stent must be
expanded to achieve its final relaxed diameter. A stent having a high recoil must be expanded to a greater diameter to achieve its
final relaxed diameter than a stent having low recoil. Practically, excessive expansion of the vessel into which the stent is to be
implanted may cause tissue damage resulting in a poor immediate result or poor long-term outcome. Stent recoil is affected by
intrinsic properties of the material used to construct the stent and the specific geometric design of the stent; therefore, measuring
stent recoil is an essential part of evaluating the design.
5. Apparatus
5.1 A means to inflate with noncompressible fluid, typically water, the delivery balloon on which the stent is mounted. The
means used must be capable of achieving the pressure required to maintain the expanded diameter of the stent until it can be
measured and may include a device to monitor pressure.
5.2 Ameanstomeasuretheouterdiameterofthestentwithoutdeformingthestent.Typically,acalibratedopticalsystem,which
does not require contact with the stent, is used.The resolution of the measurement system shall be 0.01 mm or better.The accuracy
1
This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.30 on Cardiovascular Standards.
Current edition approved MayAug. 1, 2008.2009. Published June 2008.August 2009. Originally approved in 2001. Last previous edition approved in 20022008 as
F 2079 – 02(2008).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
F2079–09
of the system shall be 2 % of reading or better.
6. Sampling,
...
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