Lessons from the real bench: non-BRS

Abstract

Bench testing of stents used in bifurcations can provide information on the general properties that influence performance including crossing profile, radial strength, recoil, flexibility and radiopacity. Problems with device delivery can be clarified. Bench testing identified that side branch dilatation caused stent distortion and elucidated correction strategies. Bench testing led to a stent design change adding connectors between hoops to help overcome the clinical problem of longitudinal distortion. Testing on the bench can determine best deployment strategies and showed that a two-step post-dilatation strategy produced the best deployment with "crush" stenting. Scanning electron microscopy showed that withdrawal of a coronary guidewire trapped between a stent (or scaffold) and a mock arterial wall during a provisional side branch stenting strategy caused only mild linear polymer coating damage. Stent fracture can cause adverse clinical events and our repetitive bend test identified the stents most resistant to fracture. Causes of obstruction of the passage of a balloon over a wire through the side of a stent include damage to the catheter tip, complex cell geometry and inadvertent passage of a wire behind a strut. Bench testing plays a major role in validation of computer modelling of bifurcation treatments and flow alterations.

Branch ostial optimization treatment and optimized provisional t-stenting with polymeric bioresorbable scaffolds

“…BVSs offers an opportunity but also poses a challenge for PCI of CBLs because BVSs differ from the conventional metal stent platforms in many ways, such as the thicker struts and more fragile structure of the currently available BVS (PLLA-BVS). [ 31 ] In this way, the previous stenting techniques and associated procedural steps developed for metal stent platforms should be re-examined until they can be safely used with BVS.…”

Coronary balloon catheter tip damage. A bench study of a clinical problem

“…The damage is one explanation for a balloon failing to cross through the side of a stent into a side‐branch. Other explanations include a wire exiting then re‐entering the stent lumen outside a strut . In addition, a lack of proximal optimization treatment (POT) may hinder crossing.…”

“…We believe that some stent designs such as those with small cells (the space between struts defined by hoops and connectors) or with complicated cell shape are more difficult to cross than those with larger cells . The more connectors there are between hoops, the smaller the cells and the more difficult they are to cross .…”

“…We have observed that one cause of obstructed passage of a balloon between stent struts to the side‐branch is damage to the balloon catheter tip (Figure ) . A damaged, flared tip can catch on a stent or scaffold strut preventing passage to the side‐branch and in addition may lead to displacement of stent struts and stent distortion .…”

The Proximal Optimisation Technique for Intervention of Coronary Bifurcations

“…When a provisional strategy is used, re-cross should ideally be performed through a distal stent cell. 12 This ensures that balloon inflation will produce better clearance of struts from the side branch ostium.…”