Traditional testing of stent and stent grafts (to standards such as ASTM F2477) involves subjecting complete devices to pressure pulsation simulating blood flow for a pre-specified number of cycles. Even if the device has not fractured, a simple pass/fail criterion is used for the test to succeed. Industry work is being undertaken to attempt to develop improved in vitro methods for characterizing and evaluating cardiovascular implant devices to provide more information about when and under what conditions fracture will take place.
To enable a representative sample of specimens to be evaluated and to reduce overall test time, multiple samples must be tested on a single system.
The multi-specimen fixture for the ElectroPuls™ E3000 All-Electric Test Instrument was developed to assist cardiovascular implant manufacturers to assess this long-term fatigue characteristics of nickel-titanium (Nitinol) and stainless-steel stent materials and structures.
Each specimen station features a fatigue-rated load cell, precision alignment adjustment and grips that are unique to the material or structure undergoing test. The entire station assembly is submerged into a temperature controlled bath to test the specimens in vitro. The test is controlled by WaveMatrix™ Dynamic Test Software that includes a number of features designed to assist users in running the test. These include integrated temperature control of the fluid bath, a live display of each load cell reading, and trend monitoring of forces to determine each specimen fracture.