Magnetic propulsion and ultrasound tracking of endovascular devices.

In this paper a robotic means of magnetic navigation of an endovascular device a few millimeters in diameter is presented. The technique, based on traditional computer-assisted surgery adapted to intravascular medical procedures, includes a manipulator for magnetic dragging interfaced with an ultrasound system for tracking the endovascular device. The main factors affecting device propulsion are theoretically analyzed, including magnetic forces, fluidic forces, and friction forces between the endovascular device and the vessel. A dedicated set-up for measuring locomotion, and for navigation with and against the flow, has been developed and preliminary tests have been performed to derive the best configuration for controlled magnetic dragging in the vascular system. Experimental outcomes are consistent with a simple analytical model that analyzes dragging of the magnetic capsule in a tube. By means of this model, different working conditions can be considered to select the appropriate conditions, for example flow rate, coefficient of friction, or magnetic properties.