This study was performed to assess the influence of the cryoinjury on the dynamics of wavefronts and to determine whether they can convert ventricular fibrillation (VF) to ventricular tachycardia (VT) in fibrillating right ventricular (RV) of swines using an optical mapping system. A cryoinjury with a diameter of 12 mm was created on the epicardium of perfused RV of swines (n = 6) and optical mapping were taken from baseline until 10 minutes after the cryoinjury. Out of 35 cryoinjuries, the images were possible to be interpreted in 32. The optical action potential could not be observed in either the cryoinjury or peri-injury sites at 1 and 3 minutes, was observed in only the cryoinjury site at 5 minutes, and recovered in both sites at 10 minutes. The cycle length of the tachycardia was 135.9 ± 23.6 msec at baseline, 176.2 ± 79.3 msec at 1 minute, 187.6 ± 97.9 msec at 3 minutes, 185.5 ± 19.2 msec at 5 minutes, and 152.1 ± 64.1 msec at 10 minutes. The cycle lengths at 1, 3, and 5 minutes after the cryoinjury were significantly more prolonged than that at baseline ( p = 0.001, p = 0.006, p = 0.016). After the cryoinjury, the VF changed to VT in 9 (28.0%), and terminated in 2 (6.3%). These changes were observed mainly within 5 minutes after cryoinjury. The cryoinjury had anti-fibrillatory effects on the tissue with VF. This phenomenon was related to a decreasing mass and stabilizing wavefronts.
A quadrupedal guidance robot that can guide people and avoid various obstacles, could potentially be owned by more visually impaired people at a fairly low cost. Most of the previous guiding systems treat the robot as the majority without fully considering the human response behavior and comfort, and the human is more like an appendage being dragged by the robot. This may lead to less accurate guiding of the human and the force experienced by the human may also undergo large changes. In this paper, we propose a novel guidance robot system with a comfort-based concept. We design a leash containing an elastic rope and a thin string, and use a motor to adjust the length of the string to ensure comfort. We use the force-based human motion model to plan the forces experienced by the human. Afterward, the direction and magnitude of the force are controlled by the motion of the robot, and the rotation of the motor, respectively. This allows humans to be guided safely and more comfortably to the target position in complex environments. The system has been deployed on Unitree Laikago quadrupedal platform and validated in realworld scenarios. (Video 1 ) † indicates equal contribution.
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