These benchtop tests provide empirical evidence for the continued structural integrity of the devices when subjected to mechanical fatigue. The tests are accelerated to obtain results in less time than physiological rates would allow. Two typical tests for these devices are pulsatile and axial fatigue testing.
Structural heart occluders and closure devices are used to treat congenital heart defects such as atrial septal defect, ventricular septal defect, patent ductus arteriosus and patent foramen ovale. While there are no specific standards for occluder device testing, many of the cardiovascular implant standards such as ISO 5840-1 (2015), ASTM F2477 and FDA Guidance 1545 (2010) cover aspects of occluder testing. In pulsatile fatigue tests, devices are subject to pulsatile radial fatigue for 100M cycles to simulate 2.5 years of implantation, with typical tests ranging from 40M to 600M cycles. Axial fatigue performance is evaluated through tensile and/or bending fatigue tests. A device failure is defined by the device manufacturer who will also examine the devices post-testing against the acceptance and/or failure criteria.
MDT uses ElectroForce 9100 Series Stent Testers for pulsatile fatigue and ElectroForce 3200 Test Instruments for axial fatigue testing. Specialty fixtures such as those shown on the right are often employed in the tests.
MDT tests are conducted in accordance with ANSI/ISO/IEC 17025-2005. Testing schedules and resource needs are determined during project kickoff meetings with MDT engineers and the customer. Services are performed in accordance with standard operating procedures and test protocols specific to the project. Standard tests do not begin without a protocol signed by both the customer and an MDT representative. For feasibility or non-standard tests, MDT will develop a method and protocol with customer input and will review the final process with the customer prior to initiation of the test.
The test equipment software monitors the cycle count and displacement throughout the duration of the test. MDT engineers monitor the test daily and record the temperature and pressure for the system, as well as the outside radial strain at predetermined positions for each device being tested. MDT sends weekly updates to ensure customers are apprised of the status of their test. Updates include raw data collected throughout the week for the customer's analysis.
MDT offers several inspection and monitoring methods including:
Tests are conducted in accordance with ANSI/ISO/IEC 17025-2005. In compliance with this standard, MDT test reports include comprehensive documentation and summary of the test protocol and results. Any test method deviations, additions, or exclusions are documented and reviewed with the customer prior to beginning the test. Information within the report includes the specific test conditions, statements of compliance with test protocol, and the estimated measurement uncertainty. The reported results only relate to the items tested. Any opinions and interpretations provided by MDT are clearly marked as such. Any additional information required by customer-specific methods will also be noted.
Please take a few moments to tell us more about your device and test requirements in our short questionnaire, and we will be happy to provide you with a quote.