Trackability, crossability, and pushability of coronary stent systems--an experimental approach

Trackability, crossability and pushability are essential properties determining the handling characteristics and deliverability of stent systems. We present objective test methods to assess these parameters quantitatively in an in vitro model. The model consisted of a 6F guiding catheter, a guide wire (0.014") and a coronary vessel model (HD-PE tubing, I.D. 2.5 mm), all immersed in 37 degrees C water. Two attached sensors measured the reactive forces occurring at the proximal catheter shaft and the distal catheter and stent segments during model passage. For crossability assessment, the setup was completed by a stenosis model, mimicking two types of eccentric circular stenoses. A comparative study provided distinctive differences in trackability, stenosis crossability, and pushability. Analyzing the proximal and distal force measurements, these differences were quantified and the qualification of a particular stent system to be successfully delivered to a model target stenosis could be rated.