Experimental investigation of the abrasive crown dynamics in orbital atherectomy

• Crown dynamics in orbital atherectomy was experimentally investigated.
• Crown motion consists of high-frequency rotation and low-frequency orbiting.
• Force on the vessel oscillates at the rotational and orbital frequencies.
• Average peak force ranged from 0.1 to 0.4 N at different rotational speeds.
• Crown dynamics associates with heat dispersion and plaque softening.

Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000 rpm in a 4.8 mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1 Hz and low-frequency orbiting at 18, 38, and 40 Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4 N at different rotational speeds.

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