Burr erosion in rotational ablation of metallic coronary stent: an electron microscopic study.

Background: Rotational atherectomy is used to penetrate resistant coronary lesions from standard balloon dilatation. These lesions may contain heavy calcification or metallic components from previously implanted stents. When the rotablator device is utilized to ablate an undilatable lesion containing metallic stent component, what happens to the rotablator burr after grinding through metal? Are there additional technical considerations of rotational atherectomy when used in metallic "ablation"?

Methods: A challenging case of rotational ablation of a freshly placed coronary stent is presented requiring 2 burrs to penetrate the undilatable lesion overlaid by the stent. Comparative scanning electron microscopic (SEM) evaluations of 3 rotablator burrs are presented including the 2 used burrs and 1 brand new burr as control. SEM analyses including gross observations and detailed account of the diamond chips (DC) on the burr-surfaces were performed.

Results: The results showed that the 1st used burr received most of the damage and erosion from the high-speed impact with the metallic stent struts. Significant scratch marks were observed on the surface of the 1st used burr. Also, a significant number of the DC on the surface of the 1st used burr were found missing, as compared to the 2nd used burr or the brand new burr.

Conclusions: The SEM findings of the rotablator burrs in this study suggest a mechanism for burr erosion when used in ablating metallic coronary stents. Also based on the SEM results, technical recommendations are discussed when the rotational atherectomy device is used to ablate metallic struts of coronary stents.