National foreword

This British Standard is the UK implementation of EN ISO 25539‑2:2020. It is identical to ISO 25539‑2:2020. It supersedes BS EN ISO 25539‑2:2012, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee CH/150/2, Cardiovascular implants.

A list of organizations represented on this committee can be obtained on request to its committee manager.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2020.

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.

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 technically revised.

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.

A list of all parts in the ISO 25539 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

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 additional informative annexes.

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 nomenclature and reporting and to enhance the utility of this document.

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 attributes specified in Clause 6 are required for compliance to this document.

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 on the unique characteristics or changes.

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 intended use.

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 these requirements is included in Annex D.

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 improve the clinical relevance of this testing.

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 strength.

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 from a previously evaluated device.

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 were previously only included in Annex D.

The revisions to the annexes to this document are as follows:

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 device that are not expected to change clinical performance.

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 Table A.1.

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) comprehensive device evaluation strategy in A.2.2.

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 European Standard was approved by CEN on 20 August 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

European foreword

This document (EN ISO 25539‑2:2020) has been prepared by Technical Committee ISO/TC 150 "Implants for surgery" in collaboration with Technical Committee CEN/TC 285 “Non-active surgical implants” the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2021, and conflicting national standards shall be withdrawn at the latest by March 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 25539‑2:2012.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 25539‑2:2020 has been approved by CEN as EN ISO 25539‑2:2020 without any modification.

1 Scope

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 general requirements for the performance of non-active surgical implants.

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 will be necessary.

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 testing are not described for these devices.

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 evaluations of such stents.

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, stents used to treat aortic aneurysms).

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 vascular stents.

This document is not applicable to procedures and devices used prior to the introduction of the vascular stent, such as balloon angioplasty devices.

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 described for these devices.

Although drug-eluting stents are within the scope of this document, this document is not comprehensive with respect to the drug-eluting properties of these devices.

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

Although absorbable stents and stents with absorbable coatings are within the scope of this document, this document is not comprehensive with respect to the absorbable properties of these devices.

NOTE 3 Absorbable implants are within the scope of ISO/TS 17137.

Although coated stents and coated stent systems are within the scope of this document, this document is not comprehensive with respect to coatings.

NOTE 4 Some coating properties are within the scope of ISO 17327‑1.

This document does not address the requirements for, and the evaluation of, viable tissues and non-viable biologic materials used in the construction of vascular stents.

2 Normative references

3 Terms and definitions

4 General requirements for stent systems

4.1 General

4.2 Type of stent

4.3 Materials of construction for stent system

4.4 Configuration and size designation for stents and stent systems

4.5 Intended clinical use designation

4.6 Balloon designation

5 Intended performance

6 Design attributes

6.1 General

6.2 Stent system

6.3 Stent

6.4 Stent system and stent

6.5 Coating on delivery system or stent

6.6 Coating on stent

6.7 Absorbable stent or coating

6.8 Drug-eluting stent

7 Materials

8 Design evaluation

8.1 General

8.2 Sampling

8.3 Conditioning of test samples

8.4 Reporting

8.5 Bench and analytical tests

8.6 Preclinical in vivo evaluation

8.7 Clinical evaluation

9 Post-market surveillance

10 Manufacturing

11 Sterilization

11.1 Products supplied sterile

11.2 Sterilization residuals

12 Packaging

12.1 General

12.2 Labelling

12.3 Information supplied by the manufacturer

Bibliography

BS EN ISO 25539-2:2020

Cardiovascular implants. Endovascular devices - Vascular stents

Current, Under Review

Published:

31 Oct 2020