Radial Force Evaluation of Stent Grafts

Stent grafts are used to treat a wide variety of peripheral arterial issues, as well as abdominal and aortic pathologic conditions like abdominal aortic aneurysms (AAA). The success of endovascular stent grafts for AAA’s has provided motivation to adapt similar technology for descending thoracic aortic aneurysms (TAA’s). Survival rates for untreated and traditionally treated (through complex thoracic surgeries) aneurysms are typically quite poor.

Advantages of stent grafts include shorter operative time, avoidance of major thoracic or thoracoabdominal incisions, and significant reductions in morbidity and mortality. Successful surgery requires the accurate placement of the stent graft to ensure it does not move, especially in upper descending thoracic aorta cases.

Typically, secure placement for stent grafts is a function of the proper selection and sizing since physiological movements of the aorta can be significant. Additionally, stent grafts have much larger diameters than coronary stents (30+ mm versus 2-3 mm). Evaluating the radial strength of a stent graft helps manufacturers to ensure efficacy and reliability of the medical device when implanted in vivo.

Instron partners with Machine Solutions Inc. (MSI) to utilize either a RX575 or RX675 stent iris on an Instron system. The fixture can also be customized and used for special specimen types to provide radial strength and stiffness over the entire graft or the securing graft ends. The control software to operate MSI’s RX fixture on an Instron system is standard Bluehill^® 3 and TestProfiler. Although room-temperature testing provides excellent comparative results, the system can also be configured with a chamber to provide simulation of body temperature.