ASTM F2081-06(2017)
(Guide)Standard Guide for Characterization and Presentation of the Dimensional Attributes of Vascular Stents
Standard Guide for Characterization and Presentation of the Dimensional Attributes of Vascular Stents
SIGNIFICANCE AND USE
4.1 Vascular stents are intended for permanent implant in the human vasculature (native or graft) for the purposes of maintaining vessel patency. The dimensional attributes of vascular stents are critical parameters that aid clinicians in the selection of devices for individual patients. This guide contains a listing of those dimensional attributes that are directly related to the clinical utility and performance of these devices, along with recommendations for consistent methods of measuring these attributes and presenting the information for use in clinical decision making. This guide can be used by the manufacturers and researchers of stents to provide consistency of measurement and labeling of these dimensional characteristics. It may have use in the regulation of these devices by appropriate authorities.
4.2 The dimensional attributes included in this guide are those that are deemed related to or possibly predictive of successful clinical performance of the stent, based on prior clinical experience; however, because of the myriad patient and medical factors that influence the clinical outcome of any individual treatment, conformance of a stent and delivery system with the recommendations in this guide should not be interpreted as a guarantee of clinical success in any individual patient or group of patients.
SCOPE
1.1 This guide covers the identification of and recommended measurement methods for those dimensional attributes of vascular stents that are deemed relevant to successful clinical performance. The delivery system packaged with and labeled specifically for use during the placement of the stent is also included within the scope of this guide.
1.2 This guide addresses only the dimensional characteristics of stents. Material property and stent functional characteristics are not addressed herein. All dimensional characteristics described in this guide refer to in vitro (“bench-top”) characterization. Because of variable patient factors, for example, vessel compliance, the actual in vivo characteristics may be slightly different.
1.3 This guide includes recommendations generally applicable to balloon-expandable and self-expanding stents fabricated from metals and metal alloys. It does not specifically address any attributes unique to coated stents or polymeric or biodegradable stents, although the application of this guide to those products is not precluded.
1.4 While they are not specifically included within the scope of this guide, stents indicated for placement in nonvascular locations, such as the esophagus or bile duct, also might be characterized by the methods contained herein. Likewise, this guide does not include recommendations for endovascular grafts (“stent-grafts”) or other conduit devices commonly used to treat aneurysmal disease or peripheral vessel trauma or to provide vascular access, although some information included herein may be applicable to those devices.
1.5 This guide does not include recommendations for balloon catheters sold as stand-alone angioplasty catheters, even though some of those catheters may be used for the delivery of unmounted stents supplied without a delivery system. Requirements for angioplasty catheters are contained in standards ISO 10555-1 and ISO 10555-4.
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.6.1 The units of measurements used throughout this guide reflect the hybrid system in common clinical use in the United States as of the time of the original approval of this guide. Since a primary purpose of this guide is to promote uniformity of labeling to facilitate the selection of devices by clinical users, the units most preferred by users wer...
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Designation: F2081 − 06 (Reapproved 2017)
Standard Guide for
Characterization and Presentation of the Dimensional
Attributes of Vascular Stents
This standard is issued under the fixed designation F2081; 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 1.6 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in
1.1 This guide covers the identification of and recom-
each system may not be exact equivalents; therefore, each
mended measurement methods for those dimensional attributes
system shall be used independently of the other. Combining
of vascular stents that are deemed relevant to successful
values from the two systems may result in non-conformance
clinical performance. The delivery system packaged with and
with the standard.
labeled specifically for use during the placement of the stent is
1.6.1 The units of measurements used throughout this guide
also included within the scope of this guide.
reflect the hybrid system in common clinical use in the United
1.2 This guide addresses only the dimensional characteris-
States as of the time of the original approval of this guide.
tics of stents. Material property and stent functional character-
Since a primary purpose of this guide is to promote uniformity
istics are not addressed herein. All dimensional characteristics
of labeling to facilitate the selection of devices by clinical
described in this guide refer to in vitro (“bench-top”) charac-
users, the units most preferred by users were selected for this
terization. Because of variable patient factors, for example,
guide. Where those units are not SI units, or derivatives
vessel compliance, the actual in vivo characteristics may be
thereof, SI units are provided in parentheses.
slightly different.
1.7 This international standard was developed in accor-
1.3 This guide includes recommendations generally appli-
dance with internationally recognized principles on standard-
cable to balloon-expandable and self-expanding stents fabri-
ization established in the Decision on Principles for the
cated from metals and metal alloys. It does not specifically
Development of International Standards, Guides and Recom-
address any attributes unique to coated stents or polymeric or
mendations issued by the World Trade Organization Technical
biodegradable stents, although the application of this guide to
Barriers to Trade (TBT) Committee.
those products is not precluded.
2. Referenced Documents
1.4 Whiletheyarenotspecificallyincludedwithinthescope
of this guide, stents indicated for placement in nonvascular
2.1 ISO Standards:
locations, such as the esophagus or bile duct, also might be
ISO 10555-1, Sterile, Single-Use Intravascular Catheters,
characterized by the methods contained herein. Likewise, this
General Requirements
guide does not include recommendations for endovascular
ISO 10555-4, Sterile, Single-Use Intravascular Catheters—
grafts (“stent-grafts”) or other conduit devices commonly used
Balloon Dilation Catheters
to treat aneurysmal disease or peripheral vessel trauma or to
provide vascular access, although some information included
3. Terminology
herein may be applicable to those devices.
3.1 Definitions of Terms Specific to This Standard:
1.5 This guide does not include recommendations for bal-
3.1.1 balloon-expandable stent, n—a stent that is expanded
loon catheters sold as stand-alone angioplasty catheters, even
at the treatment site by a balloon catheter. The stent is altered
though some of those catheters may be used for the delivery of
permanently by the balloon expansion such that the stent
unmounted stents supplied without a delivery system. Require-
remains expanded after deflation of the balloon.
ments for angioplasty catheters are contained in standards ISO
3.1.2 bridge, n—a connecting element between the radial
10555-1 and ISO 10555-4.
support aspects of a stent. A bridge may have unique design
features, as compared to a strut, to enhance longitudinal
This guide is under the jurisdiction of ASTM Committee F04 on Medical and
flexibility and minimize shortening.
Surgical Materials and Devicesand is the direct responsibility of Subcommittee
F04.30 on Cardiovascular Standards.
Current edition approved Sept. 1, 2017. Published September 2017. Originally
approved in 2001. Last previous edition approved in 2013 as F2081 – 06 (2013). Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/F2081-06R17. 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. United States
F2081 − 06 (2017)
3.1.3 crimp, v—tosecurethestentonthedeliverysystemby selection of devices for individual patients.This guide contains
compressing the stent onto the balloon. Stents sold unmounted a listing of those dimensional attributes that are directly related
must be crimped manually by the clinical staff before use. to the clinical utility and performance of these devices, along
with recommendations for consistent methods of measuring
3.1.4 crossing profile, n—a linear measure of the maximum
these attributes and presenting the information for use in
breadth of the stent/delivery system over the distal-most region
clinical decision making. This guide can be used by the
of the delivery system.
manufacturers and researchers of stents to provide consistency
3.1.5 delivery system,n—asystemthatisusedtodeliverand
of measurement and labeling of these dimensional character-
deploy a stent at the target site. A delivery system may be
istics. It may have use in the regulation of these devices by
similar to a balloon dilatation catheter; a delivery system for a
appropriate authorities.
self-expanding stent might not have a balloon.
4.2 The dimensional attributes included in this guide are
3.1.6 diameter, n—refers to the inside diameter (ID) of the
those that are deemed related to or possibly predictive of
stent unless otherwise noted.
successful clinical performance of the stent, based on prior
3.1.7 diameter, labeled, n—single value representation of
clinicalexperience;however,becauseofthemyriadpatientand
intended-use diameters, typically rounded to nearest 0.25 or
medical factors that influence the clinical outcome of any
0.5 mm. The labeled diameter is within the range recom-
individual treatment, conformance of a stent and delivery
mended in the Instructions for Use (IFU) for that particular
system with the recommendations in this guide should not be
stent and delivery system.
interpreted as a guarantee of clinical success in any individual
patient or group of patients.
3.1.8 percent solid area, n—that percentage of the projected
cylindrical side surface area (π times outside diameter times
5. Classification
length at labeled diameter) that is covered by stent material,
when the stent is expanded to its labeled diameter.
5.1 Stentsmaybeclassifiedbythefollowingcharacteristics,
as defined in Section 3.
3.1.9 premounted stent, n—a stent supplied by a manufac-
5.1.1 Mounting—Premounted or unmounted.
turer already mounted on a delivery system.
5.1.2 Expansion—Balloon expandable or self-expanding.
3.1.10 self-expanding stent, n—a stent that expands without
extrinsic force or pressure, to a size and shape close to the
6. Test Devices and General Procedures
desired final size and shape, when released from the delivery
6.1 Unless otherwise justified, all samples selected for
system. The self-expanding nature of some stents is a design
testing or measuring the attributes described in this guide
feature resulting from the materials of construction or the
should be taken from finished, clinical-quality product. Cos-
structural geometry, or both.
metic rejects or other nonclinical samples may be used if the
3.1.11 sheath, n—a movable cover that constrains a self-
cause for rejection is not related to the attribute being assessed.
expanding stent on the delivery system until its desired release
Sterilization can be omitted if it can be demonstrated that
or protects a balloon-expandable stent during delivery before
sterilization has no affect on the attribute being assessed.
deployment.
6.2 When specimen preparation (for example, manual
3.1.12 shortening/lengthening, n—the percentage change in
crimping onto a delivery system, balloon expansion), is re-
length between the undeployed mounted condition and the
quired before testing, this should be done in accordance with
expanded labeled-diameter condition.
the Instructions for Use (IFU).
3.1.13 stent, vascular, n—asynthetictubularstructurethatis
6.3 The preconditioning and test environments must be
permanently implanted in the native or grafted vasculature and
appropriately selected for each design and attribute. Tempera-
that is intended to provide mechanical radial support to
ture and fluid immersion may have a significant effect on some
enhance vessel patency. For the purposes of this guide, a stent
attributes but a negligible affect on others. For example, fluid
is metallic and not covered by synthetic textile or tissue graft
sorption may swell catheters and affect the measurement of
material.
crossing profile. Temperature may affect the final deployed
3.1.14 strut, n—the smallest individual element of the radial
diameter for stents made from shape memory materials. For
support aspect of a stent that has a solid cross section in both
measurementsforwhichdeployment,ormeasurement,orboth,
the radial and circumferential directions.
is to be made in a controlled environment, the stent or delivery
3.1.15 unmounted stent, n—a stent that is not crimped on a
system, or both, should be immersed in a water bath main-
delivery system as supplied by the manufacturer. Before use,
tained at 37 6 2°C and allowed to equilibrate.
the clinical staff must manually crimp unmounted stents onto a
6.4 The number of specimens evaluated for each diameter
delivery device.
for each stent design should be sufficient to meet the sampling
requirementsforthedesiredlabeling.Ingeneral,aminimumof
4. Significance and Use
ten replicate test devices of each size to be measured or tested
4.1 Vascular stents are intended for permanent implant in is recommended. If a single stent design is intended to be
the human vasculature (native or graft) for the purposes of deployed over a broad range of diameters by use on different
maintaining vessel patency. The dimensional attributes of size delivery systems, the dimensional attributes should be
vascular stents are critical parameters that aid clinicians in the evaluated for each stent/delivery system combination.
F2081 − 06 (2017)
7. Dimensions and Measurement Methods and the expanded labeled-diameter condition. Shortening/
lengthening should be reported as a percentage of the mounted
7.1 Deployed Diameter—Unless otherwise specified, all
(undeployed) length to the nearest 1 %.
deployed diameters refer to the inside diameter, reported in
millimetres to the nearest 0.1 mm, after balloon deflation (for
7.3 Crossing Profile:
balloon-expandable stents).
7.3.1 Measurement—With the stent premounted or hand-
7.1.1 Measurement—The outside diameter of deployed
crimped on the delivery system in accordance with the instruc-
stents should be measured by noncontacting instruments (pro-
tions for use, and the sheath (if any) in place, measure the
file projector, laser micrometer, and so forth) with a resolution
maximum diameter over the length from the proximal end of
of 0.05 mm or better. Inside diameter can then be calculated by
the mounted stent to the distal tip of the delivery system. A
subtracting twice the wall thickness (7.4). Alternatively, the
minimum of ten replicate test articles should be measured. The
inside diameter can be measured by calibrated gauges.
measurement instrument should be either noncontacting (opti-
7.1.2 Labeled Diameter—The labeled diameter is that used
cal profilometer, laser micrometer, and so forth) or a ring/hole
to identify the typical deployed size of a particular device, for
gage, and should have a resolution of 0.001 in. [0.025 mm] or
example, 3.0 mm or 3.5 mm, and must be clearly identified as
better. The crossing profile should be reported as the mean
inside or outside diameter (ID or OD). ID is preferred. The
measurement result to the nearest 0.001 in. [0.025 mm].
labeled diameter is usually rounded to the nearest 0.25 or 0.5
7.4 Strut and Bridge Thickness:
mm.
7.4.1 Measurement—Strut and bridge thicknesses of the
7.1.3 Stent System Compliance—For balloon-expandable
expanded stent may be measured by subtraction of measured
stents, a table or graph of inflation pressure versus expanded
inside and outside diameters, by direct measurement with
diameter should be developed and included in the labeling. A
specialized instrumentation, by scanning electron microscopy,
minimum of ten replicate devices should be measured at each
by profile projection, or destructively by cutting, or flattening,
stent size at each labeled inflation pressure.The expanded stent
or both, a stent for access by standard micrometers. Since
inside diameter at each inflation pressure, rounded to the
polishing or other manufacturing processes may change strut
nearest 0.05 mm, should be the mean of all measurements
and bridge thickness from that of raw material, measurements
taken on all stents at that pressure. The inflation pressure
from other-than-finished product should be used judiciously.
should be expressed in atmospheres. This attribute does not
Strut and bridge thickness should be measured at the stent
apply to self-expanding stents.
mid-length and near each end, at two circumferential locations
7.1.4 Uniformity of Expansion—The uniformity of expan-
at each axial location. If strut and bridge thicknesses are
sion refers to the difference between the largest and smallest
systematically different by design, they should be measured
diameter measurement on a single stent deployed to its labeled
and reported separately. Strut and bridge thickness should be
diameter. Uniformity of expansion is not intended to charac-
reported in inches to the nearest 0.0005 in. [0.013 mm].
terize deliberate deviations from cylindricity, such as tapered
construction, end flares, antimigration barbs, and so forth. 7.5 Percent Solid Area:
Measurements for the uniformity of expansion should be taken
7.5.1 Measurement—The reference area is the full cylindri-
at three axial locations (mid-length and close to each end) at
cal side surface
...
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: F2081 − 06 (Reapproved 2013) F2081 − 06 (Reapproved 2017)
Standard Guide for
Characterization and Presentation of the Dimensional
Attributes of Vascular Stents
This standard is issued under the fixed designation F2081; 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 This guide covers the identification of and recommended measurement methods for those dimensional attributes of vascular
stents that are deemed relevant to successful clinical performance. The delivery system packaged with and labeled specifically for
use during the placement of the stent is also included within the scope of this guide.
1.2 This guide addresses only the dimensional characteristics of stents. Material property and stent functional characteristics are
not addressed herein. All dimensional characteristics described in this guide refer to in vitro (“bench-top”) characterization.
Because of variable patient factors, for example, vessel compliance, the actual in vivo characteristics may be slightly different.
1.3 This guide includes recommendations generally applicable to balloon-expandable and self-expanding stents fabricated from
metals and metal alloys. It does not specifically address any attributes unique to coated stents or polymeric or biodegradable stents,
although the application of this guide to those products is not precluded.
1.4 While they are not specifically included within the scope of this guide, stents indicated for placement in nonvascular
locations, such as the esophagus or bile duct, also might be characterized by the methods contained herein. Likewise, this guide
does not include recommendations for endovascular grafts (“stent-grafts”) or other conduit devices commonly used to treat
aneurysmal disease or peripheral vessel trauma or to provide vascular access, although some information included herein may be
applicable to those devices.
1.5 This guide does not include recommendations for balloon catheters sold as stand-alone angioplasty catheters, even though
some of those catheters may be used for the delivery of unmounted stents supplied without a delivery system. Requirements for
angioplasty catheters are contained in standards ISO 10555-1 and ISO 10555-4.
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.6.1 The units of measurements used throughout this guide reflect the hybrid system in common clinical use in the United
States as of the time of the original approval of this guide. Since a primary purpose of this guide is to promote uniformity of
labeling to facilitate the selection of devices by clinical users, the units most preferred by users were selected for this guide. Where
those units are not SI units, or derivatives thereof, SI units are provided in parentheses.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ISO Standards:
ISO 10555-1, Sterile, Single-Use Intravascular Catheters, General Requirements
ISO 10555-4, Sterile, Single-Use Intravascular Catheters—Balloon Dilation Catheters
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
This guide is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devicesand is the direct responsibility of Subcommittee F04.30
on Cardiovascular Standards.
Current edition approved March 1, 2013Sept. 1, 2017. Published March 2013September 2017. Originally approved in 2001. Last previous edition approved in 20062013
as F2081 – 06.F2081 – 06 (2013). DOI: 10.1520/F2081-06R13.10.1520/F2081-06R17.
Available 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. United States
F2081 − 06 (2017)
3.1.1 balloon-expandable stent, n—a stent that is expanded at the treatment site by a balloon catheter. The stent is altered
permanently by the balloon expansion such that the stent remains expanded after deflation of the balloon.
3.1.2 bridge, n—a connecting element between the radial support aspects of a stent. A bridge may have unique design features,
as compared to a strut, to enhance longitudinal flexibility and minimize shortening.
3.1.3 crimp, v—to secure the stent on the delivery system by compressing the stent onto the balloon. Stents sold unmounted
must be crimped manually by the clinical staff before use.
3.1.4 crossing profile, n—a linear measure of the maximum breadth of the stent/delivery system over the distal-most region of
the delivery system.
3.1.5 delivery system, n—a system that is used to deliver and deploy a stent at the target site. A delivery system may be similar
to a balloon dilatation catheter; a delivery system for a self-expanding stent might not have a balloon.
3.1.6 diameter, n—refers to the inside diameter (ID) of the stent unless otherwise noted.
3.1.7 diameter, labeled, n—single value representation of intended-use diameters, typically rounded to nearest 0.25 or 0.5 mm.
The labeled diameter is within the range recommended in the Instructions for Use (IFU) for that particular stent and delivery
system.
3.1.8 percent solid area, n—that percentage of the projected cylindrical side surface area (π times outside diameter times length
at labeled diameter) that is covered by stent material, when the stent is expanded to its labeled diameter.
3.1.9 premounted stent, n—a stent supplied by a manufacturer already mounted on a delivery system.
3.1.10 self-expanding stent, n—a stent that expands without extrinsic force or pressure, to a size and shape close to the desired
final size and shape, when released from the delivery system. The self-expanding nature of some stents is a design feature resulting
from the materials of construction or the structural geometry, or both.
3.1.11 sheath, n—a movable cover that constrains a self-expanding stent on the delivery system until its desired release or
protects a balloon-expandable stent during delivery before deployment.
3.1.12 shortening/lengthening, n—the percentage change in length between the undeployed mounted condition and the
expanded labeled-diameter condition.
3.1.13 stent, vascular, n—a synthetic tubular structure that is permanently implanted in the native or grafted vasculature and that
is intended to provide mechanical radial support to enhance vessel patency. For the purposes of this guide, a stent is metallic and
not covered by synthetic textile or tissue graft material.
3.1.14 strut, n—the smallest individual element of the radial support aspect of a stent that has a solid cross section in both the
radial and circumferential directions.
3.1.15 unmounted stent, n—a stent that is not crimped on a delivery system as supplied by the manufacturer. Before use, the
clinical staff must manually crimp unmounted stents onto a delivery device.
4. Significance and Use
4.1 Vascular stents are intended for permanent implant in the human vasculature (native or graft) for the purposes of maintaining
vessel patency. The dimensional attributes of vascular stents are critical parameters that aid clinicians in the selection of devices
for individual patients. This guide contains a listing of those dimensional attributes that are directly related to the clinical utility
and performance of these devices, along with recommendations for consistent methods of measuring these attributes and presenting
the information for use in clinical decision making. This guide can be used by the manufacturers and researchers of stents to
provide consistency of measurement and labeling of these dimensional characteristics. It may have use in the regulation of these
devices by appropriate authorities.
4.2 The dimensional attributes included in this guide are those that are deemed related to or possibly predictive of successful
clinical performance of the stent, based on prior clinical experience; however, because of the myriad patient and medical factors
that influence the clinical outcome of any individual treatment, conformance of a stent and delivery system with the
recommendations in this guide should not be interpreted as a guarantee of clinical success in any individual patient or group of
patients.
5. Classification
5.1 Stents may be classified by the following characteristics, as defined in Section 3.
5.1.1 Mounting—Premounted or unmounted.
5.1.2 Expansion—Balloon expandable or self-expanding.
6. Test Devices and General Procedures
6.1 Unless otherwise justified, all samples selected for testing or measuring the attributes described in this guide should be taken
from finished, clinical-quality product. Cosmetic rejects or other nonclinical samples may be used if the cause for rejection is not
related to the attribute being assessed. Sterilization can be omitted if it can be demonstrated that sterilization has no affect on the
attribute being assessed.
F2081 − 06 (2017)
6.2 When specimen preparation (for example, manual crimping onto a delivery system, balloon expansion), is required before
testing, this should be done in accordance with the Instructions for Use (IFU).
6.3 The preconditioning and test environments must be appropriately selected for each design and attribute. Temperature and
fluid immersion may have a significant effect on some attributes but a negligible affect on others. For example, fluid sorption may
swell catheters and affect the measurement of crossing profile. Temperature may affect the final deployed diameter for stents made
from shape memory materials. For measurements for which deployment, or measurement, or both, is to be made in a controlled
environment, the stent or delivery system, or both, should be immersed in a water bath maintained at 37 6 2°C and allowed to
equilibrate.
6.4 The number of specimens evaluated for each diameter for each stent design should be sufficient to meet the sampling
requirements for the desired labeling. In general, a minimum of ten replicate test devices of each size to be measured or tested is
recommended. If a single stent design is intended to be deployed over a broad range of diameters by use on different size delivery
systems, the dimensional attributes should be evaluated for each stent/delivery system combination.
7. Dimensions and Measurement Methods
7.1 Deployed Diameter—Unless otherwise specified, all deployed diameters refer to the inside diameter, reported in millimetres
to the nearest 0.1 mm, after balloon deflation (for balloon-expandable stents).
7.1.1 Measurement—The outside diameter of deployed stents should be measured by noncontacting instruments (profile
projector, laser micrometer, and so forth) with a resolution of 0.05 mm or better. Inside diameter can then be calculated by
subtracting twice the wall thickness (7.4). Alternatively, the inside diameter can be measured by calibrated gauges.
7.1.2 Labeled Diameter—The labeled diameter is that used to identify the typical deployed size of a particular device, for
example, 3.0 mm or 3.5 mm, and must be clearly identified as inside or outside diameter (ID or OD). ID is preferred. The labeled
diameter is usually rounded to the nearest 0.25 or 0.5 mm.
7.1.3 Stent System Compliance—For balloon-expandable stents, a table or graph of inflation pressure versus expanded diameter
should be developed and included in the labeling. A minimum of ten replicate devices should be measured at each stent size at
each labeled inflation pressure. The expanded stent inside diameter at each inflation pressure, rounded to the nearest 0.05 mm,
should be the mean of all measurements taken on all stents at that pressure. The inflation pressure should be expressed in
atmospheres. This attribute does not apply to self-expanding stents.
7.1.4 Uniformity of Expansion—The uniformity of expansion refers to the difference between the largest and smallest diameter
measurement on a single stent deployed to its labeled diameter. Uniformity of expansion is not intended to characterize deliberate
deviations from cylindricity, such as tapered construction, end flares, antimigration barbs, and so forth. Measurements for the
uniformity of expansion should be taken at three axial locations (mid-length and close to each end) at each of two circumferential
orientations at about 90° separation. The uniformity of expansion reflects both the deviation from circularity of the stent cross
section and unintended differences in diameter along the stent length.
7.2 Stent Length:
7.2.1 Measurement—The length of mounted or expanded stents should be measured by noncontacting instruments (profile
projection, laser micrometer, and so forth) with a resolution of 0.1 mm or better. Measurements should be taken on each stent in
the mounted state and at the labeled diameter. Lengths should reflect measurements on a minimum of ten replicate devices and
should be reported to the nearest 1 mm.
7.2.2 Labeled Expanded Length—The labeled expanded length is that used to identify the typical size of a particular device, for
example, 20 mm. The labeled expanded length is usually rounded to the nearest 1 mm.
7.2.3 Mounted (Undeployed) Length—This attribute has no significance in and of itself. It provides a baseline for the
determination of shortening/lengthening. Direct measurement of the mounted length may not be possible for sheathed systems.
Other appropriate methods may be used.
7.2.4 Shortening/Lengthening—Refers to the percentage change in length between the undeployed mounted condition and 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 Measurement—With the stent premounted or ha
...
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