ISO/FDIS 25539-2

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 25539-2
ISO/TC 150/SC 2
Cardiovascular implants —
Secretariat: ANSI
Endovascular devices —
Voting begins on:
2020-05-22
Part 2:
Voting terminates on:
Vascular stents
2020-07-17
Implants cardiovasculaires — Dispositifs endovasculaires —
Partie 2: Endoprothèses vasculaires
ISO/CEN PARALLEL PROCESSING
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DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 25539-2:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2020
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ISO/FDIS 25539-2:2020(E)
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© ISO 2020

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Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 2

3 Terms and definitions ..................................................................................................................................................................................... 2

4 General requirements for stent systems ..................................................................................................................................... 6

4.1 General ........................................................................................................................................................................................................... 6

4.2 Type of stent .............................................................................................................................................................................................. 6

4.3 Materials of construction for stent system ..................................................................................................................... 6

4.4 Configuration and size designation for stents and stent systems ............................................................... 6

4.5 Intended clinical use designation ........................................................................................................................................... 7

4.6 Balloon designation ............................................................................................................................................................................ 8

5 Intended performance ................................................................................................................................................................................... 8

6 Design attributes .................................................................................................................................................................................................. 8

6.1 General ........................................................................................................................................................................................................... 8

6.2 Stent system .............................................................................................................................................................................................. 8

6.3 Stent.................................................................................................................................................................................................................. 8

6.4 Stent system and stent ..................................................................................................................................................................... 9

6.5 Coating on delivery system or stent ..................................................................................................................................... 9

6.6 Coating on stent ..................................................................................................................................................................................... 9

6.7 Absorbable stent or coating ......................................................................................................................................................... 9

6.8 Drug-eluting stent .............................................................................................................................................................................10

7 Materials ....................................................................................................................................................................................................................10

8 Design evaluation .............................................................................................................................................................................................10

8.1 General ........................................................................................................................................................................................................10

8.2 Sampling ....................................................................................................................................................................................................11

8.3 Conditioning of test samples ....................................................................................................................................................12

8.4 Reporting ..................................................................................................................................................................................................12

8.5 Bench and analytical tests ..........................................................................................................................................................13

8.5.1 Stent system and delivery system ..................................................................................................................13

8.5.2 Stent .........................................................................................................................................................................................16

8.5.3 Absorbable stents and stents containing an absorbable coating ........................................22

8.5.4 Coating on a delivery system ..............................................................................................................................22

8.5.5 Coating on a stent .........................................................................................................................................................22

8.5.6 Drug-containing stent...............................................................................................................................................22

8.6 Preclinical in vivo evaluation ..................................................................................................................................................23

8.6.1 Purpose .................................................................................................................................................................................23

8.6.2 Specific aims .....................................................................................................................................................................23

8.6.3 Protocol considerations ..........................................................................................................................................24

8.6.4 Data acquisition .............................................................................................................................................................24

8.6.5 Test report and additional information ....................................................................................................26

8.7 Clinical evaluation .............................................................................................................................................................................27

8.7.1 Purpose .................................................................................................................................................................................27

8.7.2 Specific aims .....................................................................................................................................................................27

8.7.3 Protocol considerations ..........................................................................................................................................28

8.7.4 Data acquisition .............................................................................................................................................................29

8.7.5 Final report ........................................................................................................................................................................31

9 Post-market surveillance ..........................................................................................................................................................................32

10 Manufacturing ......................................................................................................................................................................................................32

11 Sterilization ............................................................................................................................................................................................................32

11.1 Products supplied sterile ............................................................................................................................................................32

11.2 Sterilization residuals ....................................................................................................................................................................33

12 Packaging ..................................................................................................................................................................................................................33

12.1 General ....................................................................................................................................................................................................33

12.1.1 General...................................................................................................................................................................................33

12.1.2 Unit container ..................................................................................................................................................................33

12.1.3 Outer container ..............................................................................................................................................................33

12.1.4 Shipping container ......................................................................................................................................................33

12.1.5 Maintenance of sterility in transit ..................................................................................................................33

12.2 Labelling ....................................................................................................................................................................................................33

12.2.1 Container label ...............................................................................................................................................................33

12.2.2 Stents without delivery systems .....................................................................................................................33

12.2.3 Stent systems (stents with delivery system) ........................................................................................34

12.2.4 Record label ...................................................................... .................................................................................................34

12.3 Information supplied by the manufacturer .................................................................................................................34

12.3.1 General...................................................................................................................................................................................34

12.3.2 Information and instructions for use for stents and/or stent systems .........................35

Annex A (informative) Relationship between testing requirements, device attributes, and

potential failure modes and guidance for the creation of a device evaluation strategy .........36

Annex B (informative) Description of clinical effects of failure ............................................................................................53

Annex C (informative) Description of device effects of failure ...............................................................................................56

Annex D (informative) Test methods ................................................................................................................................................................58

Bibliography .........................................................................................................................................................................................................................114

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The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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This document was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee

SC 2, Cardiovascular implants and extracorporeal systems, in collaboration with the European Committee

for Standardization (CEN) Technical Committee CEN/TC 285, Non-active surgical implants, in accordance

with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This third edition cancels and replaces the second edition (ISO 25539-2:2012), which has been

The main changes compared to the previous edition are updates to the testing and clinical use of

vascular stents as well as improved consistency in nomenclature and reporting requirements.

Any feedback or questions on this document should be directed to the user’s national standards body. A

This document was prepared to provide minimum requirements for vascular stents. The rationale

for the requirements for bench tests and analyses to assess device performance, guidance on the

identification of appropriate testing to evaluate a specific device design, and guidance for developing

test methods are provided in informative annexes. Further clarification of terminology is provided in

This document has been updated to reflect current knowledge regarding the testing and clinical use of

vascular stents, reflected in modifications to the requirements in the main body and in the guidance for

developing test methods in Annex D. In addition, revisions have been made to improve consistency in

Requirements particular to the evaluation of specific characteristics of stents (e.g. coatings, drug-

elution, absorption) are incorporated by reference to appropriate standards. However, not all tests

listed in the referenced standards are applicable to vascular stents. Only tests that address the design

This revised document introduces methodology to identify appropriate testing and analyses for a

specific vascular stent, designated as the device evaluation strategy. The requirement regarding the

device evaluation strategy is in the main body. Annex A provides guidance for developing a focused

device evaluation strategy table that is specific to the unique characteristics of a device, device design

modifications, or changes in intended use. Annex A also provides guidance for the development of a

comprehensive device evaluation strategy table that may be used when it is not sufficient to focus only

NOTE ISO 25539-1:2017 includes tables that can be used to justify the testing needed for device design

modifications and changes in intended use in Annex A. In this document, this concept is called a focused device

evaluation strategy table and can be applied to a new device as well as device design modifications or changes in

The other significant modifications in the requirements include the addition of non-radial durability

testing, with guidance on the selection of appropriate testing, and specific requirements for testing

to evaluate patency-related characteristics. Guidance for the development of appropriate tests to meet

The guidance on the development of methods to address the requirement for evaluating fatigue and

durability through computational analyses has been modified significantly to include recommendations

regarding verification of the solution and validation of the computational model, as well as reporting.

The guidance on the model development for simulated use has also been significantly revised to

The specific requirements to evaluate pushability, flexibility, torquability, trackability, and deployment

accuracy of a stent system have been removed and incorporated within the simulated use evaluation

requirement to better reflect how these attributes are evaluated. Similarly, the requirement to evaluate

tubing tensile strength has been removed and incorporated within the evaluation of tensile bond

In addition to modifications to specific design evaluation requirements, guidance has been provided

regarding the assessment of the acceptability of test results. When the requirement is to quantitatively

appraise or analyse a parameter, test results generally may be compared to a quantitative value (i.e.

acceptance criteria). For characterization tests it is appropriate to provide an explanation of the

relevance of the results. Additionally, some testing may include comparison to test data or existing data

For design evaluation, requirements regarding sampling, conditioning of test samples, and reporting

have been incorporated in the main body. Guidance on these elements of testing and documentation

Annex A — A Attributes of endovascular devic- Annex A now includes the relationship between testing

es — Vascular stents — Technical and clinical requirements, device attributes, and potential failure

Annex B — Bench and analytical tests The list of tests is included in the Table D.1.

Annex C — Definitions of reportable clinical The term “reportable” clinical events is no longer used in

Annex D — Test methods This edition incorporates the sample equations as a supple-

Annex E — Supplement to the radial fatigue and There is no longer an Annex E as the sample equations as a

durability test analytical approach supplement to the fatigue durability test have been incorpo-

It is recognized by this ISO committee that many stent systems have been shown to be safe and effective

in clinical use. This update is not intended to require additional evaluation of these devices to remain

in compliance with this document as the testing would not provide useful information regarding the

expected clinical performance of the device. Manufacturers may rely on historical data gathered under

the guidance of the previous edition of ISO 25539-2. Similarly, for device modifications or changes in

intended clinical use, this update is not intended to require additional evaluation of any aspects of the

NOTE The relationship between testing requirements, device attributes, and potential failure modes is

provided in Clause A.1. Clause A.1 also provides general information regarding device evaluation strategies.

Tables A.2 and A.3 provide the rationale for the requirements specified in this document for bench tests and

analyses to assess device performance. An explanation of the table headings for A.2 and A.3 are described in

Guidance for the creation of a device-specific evaluation strategy is provided in Clause A.2. Two approaches to

create a device-specific evaluation strategy are provided: 1) focused device evaluation strategy in A.2.1; and 2)

Annex B provides a description of the potential clinical effects of failure identified in Annex A.

Annex C provides a description of the potential device effects of failure identified in Annex A.

Additional descriptions of clinical and device effects of failure are included in Annexes B and C, respectively.

Annex D provides information to consider in developing appropriate bench test and analytical methods.

This document specifies requirements for the evaluation of stent systems (vascular stents and delivery

systems) and requirements with respect to nomenclature, design attributes and information supplied

by the manufacturer, based upon current medical knowledge. Guidance for the development of in vitro

test methods is included in Annex D. This document is supplemental to ISO 14630, which specifies

NOTE 1 Due to the variations in the design of implants covered by this document, and in some cases due to

the emergence of novel types of such implants, acceptable standardized in vitro tests and clinical results are not

always available. As further scientific and clinical data become available, appropriate revision of this document

This document is applicable to vascular stents and vascular scaffolds (e.g. absorbable vascular

scaffolds) used to treat vascular stenoses or other vascular abnormalities or pathologies. Some of

the requirements are specific to endovascular treatment of arterial stenoses. Although uses of stent

systems other than treatment of arterial stenoses (e.g. venous stenting) are within the scope of this

document, comprehensive requirements and testing are not described for these uses. Similarly, specific

stent configurations (e.g. bifurcation stents) are within the scope, but comprehensive requirements and

Stents used in combination with an endovascular prosthesis to complete the treatment of a lesion,

including bridging stents (e.g. stents placed in the renal arteries after deployment of a fenestrated

endovascular prosthesis), are within the scope of this document, but test methods are not described for

the combination. ISO 25539-1 also provides information relevant to the preclinical in vivo and clinical

Vascular stents that have surface modifications, such as drug and/or other coatings, are within the

scope of this document. Stents covered with materials that significantly modify the permeability of the

uncovered stent (e.g. by covering the stent-free-surface area) are within the scope of ISO 25539-1. The

stent design or intended use might dictate the need to address functional requirements identified in

both ISO 25539-1 and this document (e.g. stents used in combination with endovascular prostheses,

Balloons integral to the stent system are within the scope of this document. This document provides

requirements beyond the requirements of ISO 10555-4, which are specific to the use of balloons with

This document is not applicable to procedures and devices used prior to the introduction of the vascular

Tacking devices intended to spot treat post-angioplasty dissections, coil supporting devices, and flow

diverters are within the scope of this document, but comprehensive requirements and testing are not

Although drug-eluting stents are within the scope of this document, this document is not comprehensive

NOTE 2 Vascular device-drug combination products are within the scope of ISO 12417-1.