ASTM F3575-24

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.
Designation: F3575 − 24
Standard Guide for
Model Development for Particulate Generation Testing of
Endovascular Devices
This standard is issued under the fixed designation F3575; 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 responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This standard provides recommendations regarding the
mine the applicability of regulatory limitations prior to use.
development of a simulated use model for particulate genera-
1.8 This international standard was developed in accor-
tion testing of endovascular devices.
dance with internationally recognized principles on standard-
1.2 Corresponding recommendations will be provided for
ization established in the Decision on Principles for the
the coronary, peripheral, and neurovascular anatomy
Development of International Standards, Guides and Recom-
respectively, as these different environments each have unique
mendations issued by the World Trade Organization Technical
challenges and considerations that should be incorporated into
Barriers to Trade (TBT) Committee.
the model development.
2. Referenced Documents
1.3 Considerations include, but are not limited to: anatomi-
cal considerations (for example, tortuosity, dimensions, disease
2.1 Other Standards:
state), working path length of the human vasculature, model/
Guidance for Industry and FDA Staff Non-Clinical Engi-
device interactions (for example, material properties, vessel
neering Tests and Recommended Labeling for Intravascu-
straightening due to device placement), and device/device
lar Stents and Associated Delivery Systems, April 18,
interactions (for example, use of delivery catheters and/or
guide wires).
Guidance for Industry and FDA Staff Coronary, Peripheral,
and Neurovascular Guidewires—Performance Tests and
1.4 Standardizing the model development allows for better
Recommended Labeling, October 10, 2019
interpretation of the test results and comparison of performance
AAMI TIR 42:2021 Evaluation of Particulates Associated
of similar medical devices.
with Vascular Medical Devices
1.5 Explicit models for devices (or groups of devices) are
not provided in this document as specific device attributes (for
3. Terminology
example, device flexibility, device material), anatomical target
3.1 Definitions:
locations, and intended patient population can strongly impact
3.1.1 context of use (COU)—defines the specific role and
model design. This document enables the development of a
scope of the model used to address a question of interest.
model that appropriately and sufficiently challenges the subject
3.1.2 model credibility—the trust, obtained through the
device with respect to particulate generation.
collection of evidence, in the capability of a model for a COU.
1.6 While this document is intended to aid in the develop-
3.1.3 question of interest—the specific question, decision, or
ment and design of the simulated use model for the assessment
concern that is being addressed.
of particulate generation, additional information regarding the
3.1.4 risk—combination of the probability of occurrence of
evaluation of the particulate matter and particulate measure-
harm and the severity of that harm.
ments can be found in AAMI TIR 42. Similarly, this document
is not intended to address testing associated with the use of the
3.1.5 simulated use model—a model that simulates or rep-
model.
licates the vasculature path through which the vascular device
will be navigated (that is, access site, tracking length, target
1.7 This standard does not purport to address all of the
location).
safety concerns, if any, associated with its use. It is the
1 2
This guide is under the jurisdiction of ASTM Committee F04 on Medical and Available from U.S. Food and Drug Administration (FDA), 10903 New
Surgical Materials and Devices and is the direct responsibility of Subcommittee Hampshire Ave., Silver Spring, MD 20993, http://www.fda.gov.
F04.30 on Cardiovascular Standards. Available from Association for the Advancement of Medical Instrumentation
Current edition approved March 1, 2024. Published April 2024. DOI: 10.1520/ (AAMI), 4301 N. Fairfax Dr., Suite 301, Arlington, VA 22203-1633, http://
F3575-24. www.aami.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3575 − 24
4. Summary of Guide device in challenging anatomy associated with a reasonably
high percentage of the expected patient population. Once the
4.1 This guide covers the development and design of a
question of interest and context of use are defined, the embolic
simulated use model for the purpose of evaluating particulate
risk from particulate generation, as measured by simulated use
generation for endovascular devices.
testing in the model, may be assessed and evaluated for the
4.2 As part of model development, this guide discusses
specified vasculature. For example, a device intended for use in
elements regarding model credibility such as model geometry,
the neurovascular arteries may carry more patient risk for
physical parameters, and historical comparators all relevant to
embolic or neurological complications with particulate genera-
the device’s intended use.
tion than a device intended for use in the peripheral vascula-
ture. Based on the risks associated with a device’s use,
5. Significance and Use
increased model credibility may be needed. Model credibility
5.1 The evaluation of particulates from endovascular de-
can be enhanced by inclusion of multiple credibility factors in
vices is a critical parameter to help ensure that the devices can
the design a single model. For example, in addition to potential
be delivered to and from the treatment site with minimal
in vitro testing with the model, animal testing may also be
unintended effects due to particulate generation.
completed to assess the effects and establish the safety of
5.2 This guide is intended for the development and design particulate generation from the device under question. The
of a simulated use model for the evaluation of particulate
level of model credibility established should be commensurate
generation by those manufacturing and/or evaluating endovas- with the associated risk of particulate generation. Model
cular devices.
credibility should be established using a rationale that consid-
ers credibility factor(s). A list of possible credibility factors is
5.3 This guide may be useful for establishment of credibility
provided in Table 1.
of a simulated use model as part of development testing and
6.2.1 Material and Manufacturing Considerations for
regulatory submission testing and filings.
Model Development—There are many materials that are
6. Procedure
available, each with its strengths and weaknesses. Proper
selection of the model materials may impact the number of
6.1 General Considerations—Construction of the model
particles collected in multiple ways. Some materials may be
should consider the clinically relevant and appropriately chal-
more challenging to clean and may retain particles from prior
lenging pathway with tortuosity reflective of the intended use.
testing or may be prone to generate additional particles.
Additional information regarding the clinical pathway and
Particles generated from the model material may also impact
tortuosity information is contained in the relevant subsections
the ability to identify and attribute particles released from the
below. The model should approximate the vessels that the
interventional devices track through to reach the deployment device. Additionally, the connections of the model with the rest
of the system need to be engineered such that the connection
site / target location. The particulate model developed should
address the intended use of the device as it relates to the disease can be made/undone with ease, remains leak-free during
handling, and does not result in cracks in the model. If the
state. Depending on the device’s intended use, different access
sites (femoral, radial, and others) and relevant tracking path- model is maintained appropriately, it can last many testing
campaigns without degradation. In addition to the consider-
ways may need to be considered. Target site design features
may also need to be considered for devices intended for ations provided below, model development should also con-
specific disease states, such as vascular occlusions, or in-stent sider factors related to particulate collection, measurements,
restenosis. Similar target site considerations to those provided and quantification, as discussed in AAMI TIR 42.
in 6.5 may also need to be applied here. To support model
6.2.1.1 Glass—Glass has long been used as the material of
credibility as discussed in 6.2, how the model represents an
choice because of its transparency, formability, and ease of
appropriately challenging clinical use environment for its
cleaning. Unfortunately, its rigidity does not mimic the com-
intended use of the device should be discussed.
pliance of vasculature. However, the rigidity does allow for the
prevention of vessel straightening, which allows for a more
6.2 Model Credibility—A simulated use model that is used
challenging assessment regarding tortuosity. Manufacturing of
to assess particulate generation for endovascular devices
glass models can be challenging, especially if the geometry
should be demonstrated to be credible for the question of
includes significant helicity and/or branching. If the manufac-
interest in the context of use. For the model to have appropriate
turing process requires manual steps, repeatability of the model
credibility, it should represent appropriately challenging vessel
dimensions can include significant variability.
diameters and tortuosity, with allowances to deviate based on
the following: material properties, manufacturability, and abil- 6.2.1.2 Silicone—Silicone and other compliant materials
ity to validate (spiking and recovery). Modifications to model can be cast accurately and can provide compliance values
diameter(s) and tortuosity may impact the device path and within physiological ranges; however, the interfacial friction
should be considered. For the purpose of this standard, a can be significantly higher than anatomically relevant tissue.
typical question of interest would be: Does my device, during Interfacial friction can also limit device deliverability as well
initial clinical use, generate particulate matter at sufficiently as cause inaccurate particulate counts from both the model and
low levels that harmful embolization is unlikely to occur? A the devices being evaluated. The material properties make the
typical COU could be: The in vitro model is intended to mimic model harder to clean and harder to get an appropriate baseline
the potential particulate generation associated with use of my count before or in between testing. Depending on the types of
F3575 − 24
TABLE 1 Credibility Factors for Model Development
Attribute Credibility Factor
Model Geometry Historical use of model geometry
Applicability of anatomical data used to generate model to COU
Quality, quantity, and breadth of anatomical data
Statistical rigor of anatomical data analysis
Physician assessment of model geometry in light of COU
Model geometry and its ability to be manufactured and allow for successful completion of spiking and recovery validation
Model dimensional verification
Model Physical Characteristics Historical use of model physical characteristics
(e.g., flexibility, friction, material) Applicability of model physical characteristics to COU
Model physical characteristics and its ability to allow successful completion of spiking and recovery validation
Ability to verify the device is utilized in a simulated use environment as intended (e.g., device visibility)
A
Historical Comparator Replication using model of harmful particulate generation from a device with known particulate-related clinical failures
A
(Model Geometry + Physical Replication using model of safe particulate generation from a device with no known particulate-related clinical failures
Characteristics)
Additional Preclinical Animal and For coating that may be friable
Human Cadaver Comparator Qualitative comparative coating mass loss
A
Particulate generation from devices with known particulate-related clinical failures may add valuable information in the assessment of model credibility. However, it may
be challenging to obtain historical comparators such as devices with known particulate-related clinical failures, and this factor may not be routinely available for
assessments.
devices that will be used in the model, silicone may be the art (2022) has several limitations for model development
scratched/spalled over multiple uses (tens of experiments). The for the purposes of this guidance document:
silicone model may be clear at the time of original manufac-
(1) The methods are not able to produce appropriately
turing but may become cloudy or less transparent over time, complex inner lumen geometries with layer lines smaller than
which may impact the utility of the model. The baseline
25 μm for centimeter size models.
particle load of the model may also increase over time due to (2) It is also expected that an additional inner lumen
repeated use. If the master model is created geometrically
coating or etching step will be needed to mask/remove the
accurate, the silicone models are expected to reproduce the
layer lines.
geometry of the vessels (dimensions, branching) with a higher
(3) The methods produce the components from smaller
complexity than glass models.
building blocks through multiple levels of in-machine assem-
6.2.1.3 Poly Vinyl Acetate (PVA)—PVA is another potential
bly (cured lines or printed pixels/voxels assembled into layers,
material, however it too suffers from many drawbacks. PVA
and layers assembled into the final part). As a result, the
can also contain residual amounts of poly vinyl alcohol. The
manufactured components are generally more prone to particu-
amount of poly vinyl alcohol can change the behavior of the
late material risks (either thinner building blocks breaking off
polymer profoundly.
or through captured partially cured parts or powder) compared
6.2.1.4 Polyurethanes—Polyuretha
...