Accelerated Wear Testing (AWT)

Stress artifacts caused by high frequencies testing of heart valve prosthesis have been reported in various versions of ISO 5840 and discussed in standardization committees for years. It is known that Accelerated Wear Testing (AWT) imposes unrealistically severe conditions not seen in normal physiologic conditions. It is common knowledge that the inertial forces on heart valve prosthesis increase significantly when exposed to accelerated wear testing conditions. To avoid unwanted in-vitro test artifacts resulting in premature failure of perfectly sound heart valve prosthesis designs, ViVitro’s AWT System with Dual Control Technology (DCT)™ maintains constant leaflet closing velocities across the entire AWT cycling period. With its proprietary and patented Dual Control Technology (DCT)™, the ViVitro’s AWT System uses two separate position feedback sensors and algorithms to control piston displacement and bypass valve independently to meet differential pressure requirements while preserving initial leaflet closing velocities, and optimizing passing cycles.

ViVitro uses its new AWT System with Dual Control Technology (DCT)™ to study the durability (repeated opening and closing) of a heart valve prosthesis under accelerated conditions. The ViVitro AWT System with Dual Control Technology (DCT)™ minimizes the probability of test artifacts resulting in false negative events during Accelerated Wear Testing, and avoid costly R&D iterations on perfectly sound heart valve prosthesis designs.

Test Procedure

For devices which may experience an immediate total loss of function, testing is performed to a minimum of  400 million cycles. For devices with demonstrated gradual degradation function, testing is performed to a minimum of 200 million cycles. For devices without established clinical history or for submissions to certain regulatory bodies additional cycles may be required.

Specified differential pressure is maintained across the closed valve  for 5 % or more of a single cycle. Using ViVitro’s expertise and equipment the maximum pressure across the valve is minimized to avoid over testing the device.

Samples experience full range of leaflet/occluder motion  as measured under normotensive conditions under pulsatile flow. This determines the maximum speed at which a sample can run.

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

Equipment

Measured Parameters

  • Number of Cycles conforming to loading conditions (target pressures across the closed valve were attained for at least 5 % of each cycle)
  • 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

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

ViVitro Labs Heart Valve Durability Tester with ADC™ technology

ViVitro Labs Heart Valve Durability Tester with ADC™ technology


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