Orbital atherectomy system (OAS) has been more common device for calcified lesion in Japan. However, the effect of OAS in bending artery have been remained unclear. The aim of this study is to make clear how OAS do work by bench test.

We performed bench test by bending plaster model. Rotablator (ROTA PRO; Boston Scientific, Japan) was performed with Rotafloppy (Boston scientific, Japan), by 200 Krpm. OAS (Diamondback; Medikit, Japan) was performed with both pullback and push manner with ViperWire with FlexTip (Medikit, Japan) by both low-speed (80 Krpm) or high-speed (120 Krpm). Each procedure was assessed by imaging modality with both IVUS (OptiCross HD; Boston scientific, Japan) and OCT (Dragonfly OpStar; Abbott, Japan). We assessed push-OAS, pull-OAS and rotablator by assessing cross-sectional images of IVUS or OCT with each 5 mm length. Moreover, and compared the site of debulking effect and device bias in each cross-sectional images.

Push-OAS (2.83 ± 0.39 mm2) have larger lumen compared pull-OAS (1.98 ± 0.35 mm2) or 1.5mm rotablator (1.82 ± 0.20 mm2), however, it was smaller than 2.0mm rotablator (3.82 ± 0.80 mm2) (p < 0.05). Moreover, Push-OAS have more orval shape than pull-OAS or rotablator (r/R = 0.75 ± 0.06 vs 0.83 ± 0.05 vs 0.88 ± 0.08, p < 0.05). Correlation between debulking effects and bias in both pull-OAS and push-OAS were less compared with those in rotablator (21 ± 31° vs 96 ± 51° vs 84 ± 39°, p < 0.01). Moreover, debulking effect of pull-OAS localized at inner side of curve (84%), since those of push-OAS did at outer side of curve(85%). 

OAS have quite different from rotablator concerned about debulking site, and this outcome could contribute for understanding the way of motion of OAS and reduction of procedural complication in bending artery.