Dynamic Failure Mode (DFM)

Dynamic Failure Mode (DFM) testing is used together with Accelerated Wear Testing (AWT) to provide a  thorough assessment of durability. Since AWT is a “test to success” approach meaning samples are intended to survive the test, DFM testing is a “test to failure” approach which is intended to characterize potential durability-related failure modes.

Test Procedure

Typically, a subset of samples that have undergone durability testing to 200 million cycles undergo continued testing until they fail. Alternatively new samples that undergo pre-conditioning (~50 million cycles of AWT) can be used.

The pressure samples experience is progressively increased at predefined time points until failure occurs.

Devices shall be inspected (microscope, photographs, and high-speed video) and functionally evaluated under pulsatile flow at each pressure increment and at least every 50M cycles.

If devices have been tested for 200 million cycles of DFM, with a minimum of 50 million cycles at the maximum pressure condition defined by ISO 5840, then testing may be discontinued. Manufactures are still required to understand the potential failure mode of a device so testing beyond this endpoint is recommended.

 

Equipment

  • ViVitro Labs HiCycle, or other Accelerated Wear Tester(s)
  • Durability Pressure Data Acquisition System
  • High speed video recording system
  • Manometer
  • Thermometer
  • Stroboscope

Measured Parameters

  • Number of Cycles conforming to loading conditions
  • Sample pressure waveforms
  • Opening and closing kinematics under highspeed video
  • Photographic documentation of the appearance of the test sample at defined inspection intervals
  • Hydrodynamic performance at defined inspection intervals
  • Detailed description of each failure

Scope

  • Surgical Valves: SAVR, SMVR, SPVR, STVR
  • Transcatheter Valves: TAVI / TAVR, TMVI / TMVR, TPVI / TPVRTMVR, TTVR / TTVI  and any other transcatheter valve
  • Biological, Polymeric, mechanical valves, tissue engineered
  • Artificial heart valves prosthesis
  • Venous valves
  • Valvular conduits
  • Any valvular prosthesis
  • Any cardiac repair device

Service Levels

Applicable Standards

  • ISO 5840-2:2021
    Cardiovascular implants — Cardiac valve prostheses — Part 2: Surgically implanted heart valve substitutes

  • ISO 5840-3:2021
    Cardiovascular implants — Cardiac valve prostheses — Part 3: Heart valve substitutes implanted by transcatheter techniques

Related Tests

OLE0909, QV-502


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