Background-Left ventricular (LV) apical rotation and twist can be estimated noninvasively by speckle-tracking echocardiography (STE). In this study, we tested whether apical rotation is an accurate index of LV contractility. Methods and Results-We measured LV basal and apical rotation by STE in 11 open-chest anesthetized mongrel dogs under 8 different inotropic stages before and after ligation of either left anterior descending (nϭ6) or circumflex coronary artery (nϭ5). We measured LV pressure simultaneously with a high-fidelity pressure catheter and calculated LV ejection fraction (EF) with the biplane Simpson method and 2D echocardiography. Maximal positive dP/dt (dP/dt max ) was used as the gold standard measurement of LV contractility. We compared LV twist and apical rotation and EF against dP/dt max by linear mixed model. LV apical rotation and twist showed dose-dependent increases and decreases after dobutamine and esmolol infusion, respectively. However, basal rotation did not change significantly during different inotropic conditions. There was a stronger association between dP/dt max and LV twist (R 2 ϭ0.747, PϽ0.001) and apical rotation (R

As described in Part I, the Lapabot was developed considering telesurgery from the initial design stage. The robot configuration is based on the master-slave structure in which the operator can be separated spatially from the patient. The distributed control architecture communicating through high-speed network enables remote control of surgical robot manipulators. In this work, we added network communication modules using user datagram protocol/internet protocol for implementation of the telesurgical system. For a stable network environment, a dedicated research network was adopted. To characterize the network environment, a data packet sender and a repeater whose packet length and packet structure are similar to those of the real data packet were developed. The developed system was evaluated through in-vitro and in-vivo experiments. With the developed system, we have successfully performed remote control of the Lapabot. The roundtrip time delay for the control signal ranged from 1.4 to 4.1 ms. The total time delay for the operator including image signal acquisition and transmission delays was under 333 ms. It did not impede surgical procedures. Initial evaluation results demonstrate the feasibility of the developed telesurgical system.

No abstract