J. C. Conti, E. R. Strope, R. Ramesh, C. S. Conti, A. E. Watkins, Dynatek Dalta Scientific Instruments, Galena, MO
The American Society for Testing and Materials (ASTM) and Association for the Advancement of Medical Instrumentation (AAMI)/ International Organization for Standardization (ISO) committees have drafted or passed standards to address the release of particulates into the vasculature by drug eluting stents during deployment and implantation. A new AAMI committee addresses these issues for all implantable medical products. This paper focuses on the concerns of these committees as well as those of stent manufacturers and academicians. A comprehensive approach to the experimental evaluation of particle shedding includes considerations that address equipment choice, system sterilization, test frequency, monitoring of stent deflection, establishment of baseline or background levels of particulates before stent deployment, deployment mechanisms into mock arteries, system hydrodynamics including overall impedance, calibration of all systems including laser counters, filtration of shed particles, and approaches to data analysis. One of the most important decisions that an investigator must make is how often the sampling is done for particulate shedding. In general, there are three temporally linked approaches. The first is simplest and yet the least informative with respect to the time course of shedding. In this case, a sample is taken from the bulk solution at the end of the acute or chronic (durability) test. The second involves the sequential sampling of the bulk solution throughout the test. The last and most informative approach is a continuous monitoring approach. This paper will focus on each step in the generation of the protocol and give pros and cons to each option. Throughout this paper, data from an actual experiment will be presented.
Summary: A comprehensive protocol has been created that allows a researcher to reliably evaluate particulate shedding from drug eluting stents. A discussion of all options that were considered will be included. Data from an actual experiment will be reviewed.
