Micro-robot for cardiovascular treatment: Study on Chronic Total Occlusions (CTO) removal

Most developed countries face high and increasing rates of cardiovascular disease (CVD). Even in Korea, the ratio of death from CVD is increasing as well. Angioplasty or atherectomy treatments have been invented to achieve revascularization but, nevertheless, the failure rate is rather high for chronic total occlusions (CTO). Micro-robot surgery which has the benefits of precision and miniaturization is emerging as one of the CTO treatments. The micro-robot for CTO treatment should contain effective CTO removal tool. The mechanism of rotational atherectomy was applied to the robot because the Rotablator™ has been reported that it is effective for the calcified lesion. Although the micro-robot is designed to remove hard calcified lesion by rotational drill tool, miniaturized actuation system would not provide enough forces or torques for removal of the lesion. Therefore, the tool should be designed to require least forces and torques during drilling. In the present study a three-axis micro milling machine and dynamometer were used to characterize reaction torque and forces with three different tool shapes. The experimental results were examined to find correlations between torque/force and cutting speeds or tool shapes. Furthermore, the design of the burr which satisfies the least torque/force condition was derived in conclusion.