Real-Time Wear Testing (RWT)

Real-time wear testing (RWT) is intended to match physiological loading conditions as closely as possible as to what would be obtained in a real patient. Due to the viscoelastic nature of some materials, Accelerated Wear Testing may actually under test devices, so RWT can be used to identify frequency dependent failure modes.

Test Procedure

Testing durations of 50 million cycles or greater will be performed.

Testing at physiologic conditions (beat rates < 200 BPM).

The target differential pressure shall be maintained across the closed valve for 20 % of the cycle.

A detailed description of valve appearance (photographs and videos)  along with  hydrodynamic functional evaluations shall be made at 0, 25, and 50 millions cycles. These results should be compared to results achieved during Accelerated Wear Testing (AWT). Note this may require an additional inspection point during AWT at 25 million cycles, as this is not typically performed.

Equipment

• ViVitro Labs Real Time Wear Tester
• Durability Pressure Data Acquisition System
• High speed video recording system
• Manometer
• Thermometer
• Stroboscope

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

• Critical for viscoelastic materials
• Required for devices without established clinical history
• Recommended for devices which may not survive the severe loading typically imparted by accelerated testing
• 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

• Standard Service
• Full Service

Applicable Standards

• ISO 5840-1:2021
  Cardiovascular implants — Cardiac valve prostheses — Part 1: General requirements

• 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

• ISO 5910:2018
  Cardiovascular implants and extracorporeal systems — Cardiac valve repair devices

Related Tests

• Durability Testing (Integrated Durability Assessment)
• Accelerated Wear Testing (AWT)
• Dynamic Failure Mode (DFM)
• Simulated Use Pre-conditioning

QV-502