Experimental Investigation of the Material Removal Rate in Grinding of Calcified Plaque by Rotational Atherectomy

Li, Xinxiao

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Experimental Investigation of the Material Removal Rate in Grinding of Calcified Plaque by Rotational Atherectomy

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Rotational atherectomy (RA) is a minimally invasive interventional procedure to remove the calcified atherosclerotic plaque from arteries, restore blood flow, and treat cardiovascular diseases. It uses a high-speed, metal-bonded diamond abrasive grinding wheel to pulverize the calcified plaque into absorbable debris via a catheter through the artery. The grinding wheel is driven by a long flexible shaft rotational up to 230,000 rpm. RA procedure has complications including peri-procedural myocardial infarction, stroke, vascular access complications, coronary dissection, abrupt vessel closure, and perforation. RA operational guidelines, including the grinding wheel size and rotational speed, have been investigated to lower complication rates. However, the guidelines are still lacking consensus, and there is confusion in the grinding mechanism of RA. Specifically, the material removing rate (MRR) of RA under different wheel sizes and rotational speeds is unclear. This study aims to investigate RA MRR over a range of grinding wheel sizes and rotational speeds based on a tissue-mimicking phantom. Three grinding wheel sizes, 1.25, 1.5, and 1.75 mm in diameter, and three-wheel rotational speeds, 120,000, 150,000, and 180,000 rpm, were investigated. A tissue phantom was 3D printed to simulate the diseased region of the artery with calcified atherosclerotic plaque. The surrogate for the calcified plague was made of gypsum plaster and inserted inside the tissue phantom. The MRR was presented as the luminal area gain and measured by microscopy and image processing. The increase of either the grinding wheel size or rotational speed leads to a higher MRR and luminal gain in RA. The highest MRR and luminal gain achieved in this study by a 1.75 mm diameter grinding wheel rotational at 180,000 rpm were 2.49 mm2/ three pass and 5.08 mm2, respectively. And the lowest MRR and luminal gain produced by the 1.25 mm diameter grinding wheel rotational at 120,000 rpm were 0.59 mm2/pass and 1.22 mm2, respectively. During RA with the same grinding wheel at a constant rotational speed, with the increase of the number of grinding passes, the MRR decreases. This study provides a thorough understanding of the wheel size and speed effects on RA MRR and engineering insights for potential improvements in RA devices and clinical operational guidelines.

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