Background and purpose: The Rotablator is an angioplasty device that is passed over a wire. It uses a high-speed rotational "burr" (2 mm in diameter) that is coated with microscopic diamond particles and cooled by saline. It rotates at high speed (approximately 200,000 rpm) breaking up endovascular blockage into minute (smaller than red blood cells) fragments. We investigated, in vitro and ex vivo, the possible use of the Rotablator for urinary stone disease.
Materials and methods: Human stones of different sizes and composition were used for the experiment. Stone impaction in vitro was modeled by wedging the stones into the proximal part of a 16F silicone Foley catheter. Likewise, an ex-vivo study was performed on stones placed into a freshly harvested swine ureter using a nitinol basket. Data regarding the drill time, remaining stone size, and ureteral damage were collected.
Results: Overall, 15 stones were treated (10 in vitro and 5 ex vivo). The device successfully drilled through all the stones, along the path of the guidewire, allowing complete passage of the burr. The pretreatment mean stone size for the silicone and ureteral testing was 65 mm(3) and 34 mm(3), respectively (both P < 0.01). The post-treatment size was 54 mm(3) and 24 mm(3), respectively. Average treatment time was 100 seconds. No visual macroscopic ureteral damage or perforation was observed.
Conclusions: In vitro, the Rotablator is capable of drilling through stones with minimal damage. Drilling, however, occurred alongside the stone in which the guidewire was located and, thus, stone fragmentation appears to be minimal. Further studies are necessary to investigate other burr configurations and the use of the Rotablator for the fluoroscopic-guided passage of ureteral impaction in difficult clinical settings.