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ISO 25539-2 Test methods endovascular devices - vascular stents

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ISO 25539‑2:2020 Cardiovascular implants - Endovascular devices - Part 2: Vascular stents

ISO 25539-2 specifies mechanical performance tests as core bench evaluations for stent systems (stent + delivery system + integrated balloon), plus supplementary tests for materials, biology, clinical, sterilization, and packaging. Include the Axial, bending, torsional, Pulsatile Durability, Radial Loading test etc., Below is the details mechanical testing introduction, UnitedTest offer most of the testing equipment required, contact with our engineer today for more details at export@unitedtest.com. 


Mechanical tests verify short-term operability (delivery, deployment, withdrawal) and long-term structural stability (fatigue, patency) of vascular stents. 

All tests are performed at 37±2 °C (physiological temperature) with sterilized, clinically conditioned samples.


1, Fatigue & Durability Tests 

Evaluate long-term structural integrity under cyclic physiological loads (10-year design life simulation).

ItemDetails
Test TypesRadial loading, axial, bending, torsional, compressive fatigue & durability
Test EquipmentCyclic fatigue tester, load/displacement sensor, cycle counter, 37 °C PBS fluid bath, mock vessels (silicone), microscope/SEM/radiography
Test SampleFull stent or justified segments; worst-case failure-risk size; pre-conditioned (tracked through tortuous anatomy, deployed); overlapping stents/stent+endovascular prosthesis
Test Procedure

1.Sterilize and condition samples (simulate clinical delivery/deployment)

2.Mount stent in mock vessel/test fixture (anti-migration)

3.Apply physiological cyclic load: radial (pulsatile pressure), axial (stretch/shorten), bending (radius of curvature), torsion (angle/length), compression (perpendicular to axis) 

4.Cyclic loading: ≥380 million cycles (pulsatile, 10-year life); non-pulsatile cycles justified

5.Periodic inspection (deformation, migration); post-test inspection (fracture, wear, delamination) with SEM for fracture analysis

FeaturesMulti-directional load simulation; accelerated cyclic testing; not applicable to absorbable stents
ImportancePrevent in-vivo fracture, embolism, or occlusion; validate long-term mechanical reliability
ApplicationAll vascular stents, especially stents near joints/moving anatomy (superficial femoral, venous stents)


2. Stent System Mechanical Tests

Evaluate delivery system-stent mechanical interaction (delivery, deployment, withdrawal safety).

ItemDetails
Test ItemsDislodgement force (pre-mounted balloon-expandable), deployment force (self-expandable), tensile/torsional bond strength, profile effect/flaring
Test EquipmentUniversal mechanical tester, torque tester, tortuous anatomical model, diameter measuring device.
Test SampleSterilized stent systems (stent + delivery system)
Test Procedure

Dislodgement force: Fix stent → pull delivery system → record peak proximal/distal force 

Deployment force: Simulate anatomy → measure force for all deployment steps

Bond strength: Tension/torsion delivery system joints → test failure load/torque

Profile effect: Track through tortuous path → measure stent-balloon outer diameter difference.

FeaturesFocus on delivery system performance; simulate clinical operating forces
ImportancePrevent intra-procedural dislodgement, bond failure, or vessel injury
ApplicationAll stent delivery systems


3. Integrated Balloon Mechanical Tests

Validate performance of balloons integrated with stent systems.

ItemDetails
Test ItemsBalloon deflation time, rated burst pressure (RBP), balloon fatigue, dogboning
Test Equipment37 °C water bath, inflation device, pressure gauge, timer, diameter measuring tool
Test SampleStent system-integrated balloons
Test Procedure

Deflation time: Inflate → deflate → record time to deflated stat

RBP: Incremental inflation → measure burst pressure → calculate RBP (99.9% reliability, 95% confidence)

Fatigue: Cyclic inflation to RBP → test tolerated cycles

Dogboning: Inflate to max pressure → measure balloon diameter beyond stent ends

FeaturesSpecific to stent-integrated balloons (not standard angioplasty balloons)
ImportancePrevent balloon rupture, slow deflation, or vessel overstretch injury
ApplicationBalloon-expandable stent systems


4. Patency-Related Mechanical Tests

Verify lumen patency (resistance to collapse, kink, deformation).

ItemDetails
Test ItemsPerpendicular load compression resistance (self-expandable), perpendicular/radial crush resistance (balloon-expandable), radial force (self-expandable), kink resistance, stent-free/outer surface area
Test EquipmentUniversal mechanical tester (flat plate/cylindrical compression fixtures), radial force tester (iris tester), kink test gauge/bending model, laser micrometer, CAD software (surface area)
Test SampleDeployed stents (full size); overlapping stents (if clinically applicable)
Test Procedure

Compression/crush: Apply perpendicular/radial load → measure force at specified displacement/permanent deformation → check shape recovery

Radial force: Constrict/expand self-expandable stent → record outward force at target diameters

Kink resistance: Bend stent → measure minimum kink-free radius; check recovery (self-expandable)

Surface area: Calculate free surface area (%) and outer contact area (mm²) via CAD

FeaturesDifferentiate self-expandable/balloon-expandable and implant sites; direct patency correlation
ImportanceMaintain lumen patency; avoid collapse, kink, or branch vessel obstruction
ApplicationVenous stents, peripheral artery stents, stents in non-aortic/non-coronary/non-renal locations


Related products and device

ASTM F2942 Vascular Stent Uniaxial Tension Durability Testing Machine

Vascular Stent Uniaxial Tension Durability Testing Machine is designed to perform accelerated axial fatigue and durability testing on vascular stents in accordance with ISO 25539 and ASTM F2942 standards, evaluating their long-term structural integrity under cyclic axial loading.

ASTM F2942 Vascular Stent Bending Durability Tester

Vascular Stent Bending Durability Tester is designed to perform accelerated bending fatigue testing on vascular stents in accordance with ISO 25539 and ASTM F2942 standards, evaluating their long-term structural integrity under cyclic bending loading.

ASTM F2942 Vascular Stent Torsion Durability Tester

UTCA-VST6 Vascular Stent Torsion Durability Tester is designed to perform accelerated torsional fatigue testing on vascular stents in accordance with ISO 25539 and ASTM F2942 standards, evaluating their long-term structural integrity under cyclic torsional loading.

ASTM F3211 Multi‐Axis Fatigue Torsional & Bending testing system

Multi‐Axis Fatigue Torsional & Bending testing system understake this task, used to check the torsion and bending, tension test for the Intramedullary lengthening nail/Intramedullary leg lengthening implants nails.

ASTM F2477 Vascular Stent Radial Pulsatile Fatigue Testing System

Radial Pulsatile Accelerated Durability Tester is designed to perform accelerated pulsatile durability testing on vascular implants such as stents or valve frames, in accordance with relevant requirements of ISO 25539 and ASTM F2477.

ASTM F3036 Single column universal testing machine

A single column tensile tester is a sophisticated material testing instrument designed for measuring mechanical properties of various materials under tension, compression, bending, shear, and other loading conditions. As the name suggests, it features a single vertical column supporting a moving crosshead that applies force to test specimens.

ASTM F3067 Segmented head stent radial loading compression test fixture

Segmented head stent radial loading compression test fixture is a specialized designed to evaluate the radial mechanical properties of vascular stents, including radial strength, chronic outward force (COF), collapse pressure, and radial stiffness. Conform with ASTM F3067, ISO 25539-2

ASTM F2606 Three-Point Bending Test fixture for Vascular Stent

Three-Point Bending Test fixture for Vascular Stent is a specialized mechanical testing instrument designed to evaluate the flexural properties of balloon-expandable vascular stents and stent system. Conform with ASTM F2606, ISO 25539-2.

Related Standard

ISO 25539-1 Test methods of endovascular prostheses, vascular stents grafts

ISO 25539‑1 applies to endovascular prostheses (stent‑grafts) and their delivery systems. It defines a complete set of mechanical tests covering fatigue, fixation, patency, strength, and dimensional stability.  Mainly test include Axial, bending, torsional, Pulsatile Durability, Radial fatigue.

ASTM F2477 Test for in-vitro Pulsatile Durability Testing of Vascular Stents

ASTM F2477 designed to evaluate the long-term fatigue durability and radial cyclic deformation resistance of vascular implants under simulated physiological pulsatile loading conditions. It is crucial for simulating the cyclical stresses these medical devices endure inside human blood vessels. 

ASTM F3067 Radial Loading Test of Vascular Stents

ASTM F3067 establishes in vitro test frameworks to characterize the radial mechanical performance of balloon-expandable vascular stents and self-expanding vascular stents. It quantifies three key indicators: radial strength and collapse pressure for balloon-expandable stents, and chronic outward force (COF) for self-expanding stents.

ASTM F2606 Three-Point Bending Test for Balloon-Expandable Vascular Stents and Stent Systems

ASTM F2606 defines quantitative three-point bending procedures to characterize the bending flexibility and stiffness of balloon-expandable vascular stents and stent systems (pre-deployment and deployed states). It is a critical testing protocol in the biomedical engineering field. Since vascular anatomies are naturally curved and tortuous, a stent must be flexible enough to navigate through the delivery pathway (trackability) and conform to the vessel's curvature once deployed without causing vascular trauma . This standard provides the guidelines to measure these mechanical properties accurately.

ASTM F2942 Vascular Implants Axial, bending, torsional and compression durability testing

ASTM F2942 specifies in vitro test methodologies to evaluate the cyclic durability of vascular stents under non-radial mechanical deformations (axial, bending, and torsion) that occur in vivo due to musculoskeletal motion, breathing, or cardiac activity. 

ASTM F3036 Testing of Absorbable Stents

ASTM F2942 specifies in vitro test methodologies to evaluate the cyclic durability of vascular stents under non-radial mechanical deformations (axial, bending, and torsion) that occur in vivo due to musculoskeletal motion, breathing, or cardiac activity. include Axial, bending, torsional, Pulsatile Durability, Radial Loading etc., test. 

ISO 17137 Test Methods of cardiovascular absorbable implants

Based on the ISO/TS 17137 standard the evaluation of mechanical properties is a critical part of the design and safety validation process. Mechanical Evaluation like tension, radial force, Cyclic Fatigue Durability like constant pulsing. Because absorbable implants lose their structural integrity over time through degradation, their mechanical performance must be assessed not just at the time of implantation, but throughout their intended functional lifetime. 

ISO 12417-1 Test Methods for Cardiovascular implants and extracorporeal systems

ISO 12417-1 specifies requirements for Vascular Device-Drug Combination Products (VDDCPs) (drug-eluting stents, drug-coated balloons, drug-bearing vascular grafts, etc.). It mandates mechanical tests for the device part (DP) (to verify structural/functional integrity) and a suite of drug-related, physicochemical, biological, and clinical tests. Mechanical performance must comply with device-specific standards (ISO 25539-2, ISO 10555-4, ISO 7198) and remain unaffected by the drug-containing part (DCP). 

ISO 7198 Mechanical Tests and Other Evaluations for Vascular Implants

ISO 7198 specifies test and performance requirements for tubular vascular grafts and vascular patches (surgical vascular prostheses). It defines mechanical tests (with full method/equipment/sample details) and other physicochemical, biological, dimensional, preclinical/clinical tests.

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