Kinematic-model-free positional control for robot-assisted cardiac catheterization

Cardiac electrophysiology (EP) [1] is a typical example of catheter interventions for cardiovascular diseases, in which a catheter is delivered from the femoral vein to perform ablation in the heart chamber. It requires precise targeting of the catheter tip at a small region for radio-frequency (RF) ablation of tissues in order to isolate the abnormal electrophysiological signals causing the arrhythmia. This procedure is considered as an effective treatment for heart rhythm disorder (arrhythmia). However, maneuvering of such a long and flexible catheter inside the cardiac chamber is still a challenging task even for the latest advances in the robotic-assisted platforms. The continuum structure of catheter, as well as the rapid cardiac motion, make it very difficult to predict the catheter motion during an intervention. Previous research attempts [2] aim to control the catheter motion by deriving its explicit kinematic model; however, a number of assumptions, such as that the catheter shape bends as a series of connected arcs without torsion [3], are required. In the real practice, the number and length of these arcs can be changed rapidly due to numerous contacts along the vascular tissue. To avoid dependency on model based kinematic control for catheter navigation, we developed a model-free control interface capable of providing effective teleoperated control of a clinically used catheter, with the incorporation of visual-motor alignment. A sequential sampling method, particle filtering [4], is used to update the mapping from actuation input to our proposed virtual camera coordinate smoothly in order to realign the visual-motor coordinates time-by-time. It aims to provide the operator with a consistent motion reference to maneuver the catheter tip aiming at the desired target in unknown or unstructured constrained environments. Subject tests have been conducted to demonstrate how the proposed approach enhances the navigation effectiveness.