Stent Testing

An in-line continuous particulate counting system is used to assess the number and sizes of  particles generated during simulated use in real-time inside an anatomical model.

Uses the camera to evaluate the ability of the device to adequately contact the vessel wall upon deployment.

A measurement of the maximum diameter over the length of the delivery system, from the proximal end of the mounted stent to the distal tip.

The goal of the test is to determine the load required to cause clinically relevant buckling or a deflection equivalent to a diameter reduction of at least 50%, and determine the load and the displacement required to permanently deform or fully collapse the stent. The purpose of the test is to also determine whether the stent recovers from its original geometry after testing.

The goal of the test is to determine the load or deformation characteristics of the stent while a circumferentially uniform radial load is applied.

Using a constant displacement a radial load is applied to the sample. Force-diameter curves of stent like structures are determined while loading and unloading the sample according to a specified profile.

A contactless optical gauging machine is used to measure dimensional attributes of the device.

The purpose of this test is to determine the deformation of the device in response to a compressive force applied longitudinally along axis of the device.

Force required to initiate stent displacement from its initial crimped position and to completely dislodge the stent from the delivery system.

Ability of the device to bend in order to accommodate the predetermined clinically relevant radius or angle it will be required to negotiate during access and delivery.

The purpose of this test is to determine the deformation of the device in response to a localized compressive force perpendicularly applied to the longitudinal axis of the device, and to determine whether the stent recovers its original geometry after testing.

The reference area is the full cylindrical side surface area for the stent expanded to the labeled diameter (∏ X outside diameter X length at labeled diameter). The solid area is estimated by CAD software. The solid area is determined on unexpanded stents and assumed not to change significantly during expansion. The percent solid area is the ratio of the solid area to the reference area and is reported as a percentage.

Ensure the distal tip of crimped stent remains in contact with the balloon at all times, while navigating through a tortuous path. The degree of flaring of the stent away from the balloon is measured.

Determine the fatigue resistance of a stent using an in-vitro accelerated test.

The force-diameter curves of stent like structures are determined while loading and unloading the sample according to a specified profile.

Test specimens are exposed to X-Ray levels necessary for the imaging system and the product or material. Digital analysis method is used to produce the images in accordance with the equipment manufacturer’s instructions. Radiopacity of the device is determined by qualitatively comparing X-ray image(s) of a test sample and a user-defined standard with or without the use of a body mimic.

The goal of the test is to assess the elastic recoil and foreshortening of balloon expandable stents.

Before conducting other evaluations, test samples should undergo all the steps a finished device would go through before being implanted in the patient.

Devices can be subjected to various physiological pulsatile flows and pressures.

For balloon-expandable stents, a table of inflation pressure versus expanded diameter is developed and included in the labeling. The expanded stent inside diameter at each inflation pressure is the mean of all measurements taken on all stents at that pressure. The inflation pressure is expressed in atmospheres.

Strut and bridge thicknesses of the expanded finished stent are measured by direct measurement using a calibrated optical system. Strut and bridge thickness are measured at the stent mid-length and near each end, at two circumferential locations at each axial location. If strut and bridge thicknesses are systematically different by design, they will be measured and reported separately. Direct measurement may require test samples destruction by cutting, or flattening, or both.

Stent expansion uniformity: Difference between the largest and smallest diameter measurement on a single stent deployed to its labelled diameter.