Defective Stent

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Stents are integral for maintaining blood flow in some people’s bodies. A defective stent could cause serious complications or even death. If you or someone you know has been injured or believed to have been injured by a defective or recalled stent, contact RepresentYou.com now. We will do what we can to find you the best stent attorney who may be able to help you with your case. Call us, 24 hours a day, 7 days a week.

Does Boston Scientific Corp. and Johnson & Johnson Have Recalled Stent’s?

A stent is an artificial tube made out of a wire mesh that is used to widen an artery during an angioplasty, a technique in which a narrowed or blocked vessel is widened. The stent is put over a balloon catheter in a collapsed state and moved to the point of blockage, at which point the balloon is inflated. The stent expands and widens the artery, restoring blood flow. Two types of stents have proven possibly defective: Boston Scientific Corp.’s drug-eluting stents and the Johnson & Johnson and the Ancure endograft. The drug-coated stents carry a risk of blood clots that emerge around a year after the stents are inserted. The Ancure endografts are not defective in themselves, but the equipment used to insert the grafts could become lodged and sometimes emergency surgery is necessary to remove them.

FDA Stent Information

Document issued on: April 18, 2010

This document supersedes the guidance “Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems” dated January 13, 2005.

Guidance for Industry and FDA Staff

Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems

This guidance represents the Food and Drug Administration’s (FDA’s) current thinking on this topic. It does not create or confer any rights for or on any person and does not operate to bind FDA or the public. You can use an alternative approach if the approach satisfies the requirements of the applicable statutes and regulations. If you want to discuss an alternative approach, contact the FDA staff responsible for implementing this guidance. If you cannot identify the appropriate FDA staff, call the appropriate number listed on the title page of this guidance.

I. Introduction

This guidance provides FDA’s current thinking on non-clinical engineering tests that are submitted in investigational device exemption applications (IDEs) and premarket approval applications (PMAs) to support the safety and effectiveness of intravascular stents and their associated delivery systems. This guidance also provides recommendations for labeling for these devices.

FDA’s guidance documents, including this guidance, do not establish legally enforceable responsibilities. Instead, guidances describe the Agency’s current thinking on a topic and should be viewed only as recommendations, unless specific regulatory or statutory requirements are cited. The use of the word should in Agency guidances means that something is suggested or recommended, but not required.

Definition of Terms Used in this Guidance

Intravascular Stent

Intravascular stents are also known as endovascular stents or vascular stents. This document uses the term “intravascular stent” to refer to intravascular, endovascular, and vascular stents.

An intravascular stent is a synthetic tubular structure intended for permanent implant in native or graft vasculature. The stent is designed to provide mechanical radial support after deployment; this support is meant to enhance vessel patency over the life of the device. Once the stent reaches the intended location, it is expanded by a balloon or self-expanding mechanisms defined below.

Balloon Expandable Stent

A balloon expandable stent is expanded by a balloon catheter. The diameter of the stent increases as the balloon diameter increases. The stent remains expanded after deflation of the balloon.

Self-expanding Stent

A self-expanding stent’s diameter increases from its pre-deployed size to its post-deployed size in the absence of balloon inflation or other mechanical assistance. The self-expanding quality can result from material properties or geometry or both.

Stent Delivery System

A stent delivery system delivers a stent to a target site and then deploys the stent.

A stent delivery system for a balloon expandable stent consists of a balloon catheter. Self-expanding stent delivery systems may or may not include a balloon.

II. Scope

This guidance document addresses self-expanding and balloon expandable extracranial intravascular stents and their associated delivery systems. The scope includes extracranial intravascular stents placed in coronary or peripheral arteries and saphenous vein grafts but is not limited to stents used in these locations; other vascular indications outside of the intracranial vasculature are also included.

Intravascular stents, including balloon expandable and self-expanding stents, are class III devices whose product codes are given in the table below.

Table 1: Product Codes for Stents Addressed in this Guidance

Product Code Device
MAF Stent, Coronary
NIM Stent, Carotid
NIN Stent, Renal
NIO Stent, Iliac
NIP Stent, Superficial Femoral Artery

These devices require a premarket approval (PMA) application before marketing. See sections 513(a) and 515 of the Federal Food, Drug, and Cosmetic Act (the Act) and 21 CFR Part 814.

Clinical studies conducted in the United States in support of a PMA approval must be conducted under the Investigational Device Exemptions (IDE) regulation, 21 CFR Part 812. FDA believes that the intravascular stents addressed by this guidance document are significant risk devices as defined in 21 CFR 812.3(m),1 and as such, are not exempt from the requirement to submit an investigational device exemption (IDE) application (21 CFR 812.2(b), 812.20(a)(1). When an IDE application is required, a sponsor must not begin a clinical trial in humans in the United States until FDA has approved the application (21 CFR 812.20(a)(2), 812.42). Sponsors of such studies must comply with the following:

  • IDE regulations (21 CFR 812)
  • Regulations governing institutional review boards (IRB) (21 CFR 56)
  • Informed consent (21 CFR 50).2

After FDA has approved a device, clinical studies conducted in accordance with the indications in the approved PMA, including clinical design validation studies conducted in accordance with the quality systems regulation, are exempt from the investigational device exemptions (IDE) requirements. However, such studies must be performed in conformance with the regulations governing institutional review boards (21 CFR Part 56) and informed consent (21 CFR Part 50).

Non-vascular stents meant for use outside the vasculature are not included in the scope of this document. This document also does not include stents used in the intracranial vasculature. You should contact the Division of Reproductive, Abdominal, and Radiological Devices for information about biliary stents, the Division of Anesthesiology, General Hospital, and Infection Control Devices for information about non-vascular stents, or the Division of Ophthalmic, Neurological, and Ear, Nose, and Throat Devices for information about stents used in the intracranial vasculature.

Some of the tests (and labeling recommendations) in this guidance are relevant to covered (NIV), drug-eluting (NIQ), and biodegradable stents, and stents used to treat aneurysms or dissections. However, FDA recommends additional testing to fully characterize these devices. For drug-eluting stents, please refer to the draft document Coronary Drug-Eluting Stents— Nonclinical and Clinical Studies. For other coated stents, FDA recommends that you assess the need for additional testing to address coating characterization, coating integrity, and coating durability. The Interventional Cardiology Devices Branch and the Peripheral Vascular Devices Branch are available to discuss additional testing details for these stents and indications.

III. Content and Format of Test Data

A. Summary Reports

We recommend that you present test data in a summary that includes the elements described below.

Table of Contents

You should place a table of contents at the front of the document. Each line listing in the table of contents should refer to major section titles and the page numbers where each section can be found.

Test Summaries

You should briefly describe all tests performed.

Test Data Summaries

You should include test data summaries for all tests. The summaries should contain:

  • minimum measured value (min)
  • maximum measured value (max)
  • mean
  • standard deviation of the test data (std. dev.).
Summary of Conclusions

You should summarize your conclusions regarding whether the results support the safety and effectiveness of your device for each test.

B. Test Reports

You should include full test reports for all tests performed. Your test reports should include the sections described below.

Test Specimen Information

Your test specimen description should include:

  • number of test specimens
  • size (diameter, length, or other relevant dimensions) of all test specimens
  • rationale for the number of test specimens and sizes tested
  • whether the specimens represent the finished product
  • sterilization parameters and number of sterilization cycles applied to the test specimens.
Test Protocol

You should submit your test method or protocol. It should contain enough detail that an individual familiar with intravascular stent testing will be able to interpret the test results.

Protocol Deviations

You should describe any protocol deviations and their effect on the ability of the test data to support the safety and effectiveness of the device.

Test Parameters and Acceptance Criteria

You should report the test parameters and acceptance criteria that you use, including:

  • an explanation of and rationale for critical test parameters
  • specifications or acceptance and rejection criteria
  • a rationale for the specification or acceptance and rejection criteria based on the clinical requirements of the device.
Raw Data

We recommend that you include all raw data in appendices or on a CD-ROM, or make the raw data available for our review upon request.

Test Results

You should summarize your test results and include statistical analysis when it is appropriate.

Data Analysis

You should analyze the data, including any outlying points and anomalous results, and explain whether the data meet the given acceptance criteria.

Conclusions

We recommend that you describe the conclusions drawn from the test results, and the clinical significance of the conclusions.

C. Test Protocols

You should establish protocols for all experiments or computational analyses, including acceptance criteria when applicable, before you perform the tests. Established test protocols help to ensure consistent repetition of tests and allow comparison of data between test runs.

We are willing to informally review and provide comments on test protocols prior to conduct of a test, if there are aspects of a particular test that you feel might benefit from FDA input. While FDA does not approve test protocols, our input before testing may improve your ability to demonstrate the performance characteristics of your device.

Your test protocols should assess device performance when exposed to the most extreme clinical conditions that your device is likely to experience. Both device configuration and physiologic conditions affect the performance of devices in the human body. We recommend that you evaluate extreme device dimensions, tolerances, sizes, and any other important device parameters in your testing program. We also recommend that you examine the outer limits of physiologic variables such as blood pressure, vascular compliance, and anatomic types. You should clearly state all test conditions in the test protocol and support them with references to applicable literature, standards, or both.

Occasionally, the worst performing combination of device configuration and physiologic conditions occurs in the mid-range of the relevant variables. You should check for this situation when developing your protocols to ensure that you test the worst performing combination.

Several of the tests listed in this guidance do not apply to all intravascular stents and delivery systems. The designs or clinical indications to which these tests do apply are noted in their descriptions. We believe that each test helps to support the safety and effectiveness of intravascular stents for their stated indication. Each test’s clinical or engineering significance is described in Section V.

If you believe a test recommended in this guidance does not apply to your device, you should include a heading for the test in your test summary, followed by an explanation of why the test is not applicable. We will then be aware that you did not inadvertently omit it from your application.

Your explanation should include a rationale for why you do not think the test should be performed in order to support the safety and effectiveness of your device. Your rationale should clearly demonstrate, by reference to a Failure Modes and Effects Analysis (FMEA) or other risk analysis method, that the particular test or data set is not necessary or appropriate to support the safety and effectiveness of your device. Alternatively, you may identify measures you have taken to mitigate the risks associated with the device in the failure mode that would usually be evaluated using the test that you have not performed.

Intravascular stents have been in clinical use for over a decade and some designs are in their fourth or fifth generation. Some attributes may not be modified when changes are made in the design of a next-generation device. For a particular attribute, rather than providing original data for a next-generation design, it may be appropriate to reference previously tested stents in the same device family. However, a reference to previous generic device experience, for example, “alloy X has been used in stents,” generally is not adequate. If you choose to reference testing previously performed on already marketed stents, you should explain why the previous testing is relevant. If a particular attribute of the next-generation device is re-evaluated, a comparison of the results to those of the previous generation may be helpful.

Sample Selection

You should use a statistically significant sample size whenever possible. When using a statistically significant number of samples is not possible, you should provide a scientific rationale to support the number of samples tested in your test summary and test protocols, and provide reasonable assurance that the test results support the safety and effectiveness of the device.

All test samples should represent the finished product. Your devices should be sterilized by the final production process, including repeat sterilization cycles. You should note any tests that use samples that are not finished, sterilized product in the test summary and test protocols, and explain why doing so does not affect the applicability of the test results to the evaluation of safety and effectiveness of the device.

You should test the full range of sizes that you intend to commercially distribute. The recommended default paradigm is a 2 x 2 factorial of the largest and smallest diameters and lengths, also known as the “four corners” paradigm for each different stent design. We recommend a different set of sizes for some of the tests in Section V. Table 2 illustrates the four corners concept for a typical coronary stent. If you do not test a device using the four corners paradigm or the recommended sizes for a particular test, you should provide a scientific rationale to support the sizes that you do test in the test summary and test protocols. For some tests, we may recommend that you perform an analysis to identify the size or sizes that represent the worst case.

Table 2: Four Corners Test Paradigm Example

Stent
Diameter
(mm)
Stent Length
(mm)
8 12 18 24
2.5 X X
3.0
3.5
4.0 X X

X = Recommended sizes for testing

You can read additional information here: The Food and Drug Administration

How Can I find a Stent Recall Lawyer

If you or a loved one has suffered injury or death due to a defective or damaged stent you need a stent attorney, RepresentYou.com may be able to help you find the right one. There has been stent recalls and defective medical product recalls. RepresentYou.com product liability and personal injury lawyers can potentially take cases on a contingency fee basis. This means your lawyer cmay pay all the costs and a fee charged for a lawyer’s services only if the lawsuit is successful or is favorably settled out of court. Contingent fees are usually calculated as a percentage of the client’s net recovery. No Win, No Fee.

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