From the Stereotaxis website:
Magnetic navigation is an interaction between:
— A magnetic field of specified direction and magnitude, positioned externally to the patient
— A tiny magnet in the tip of the interventional device
The end result is alignment of the distal tip of the magnet with the field direction — literally steering catheters and guidewires through the heart and the coronary vasculature.
Magnets are rotated to change field orientation as an automatic advancement system automatically controls catheter advancement and retraction — eliminating any pulling or pushing on the interventional device.
News 8 Austin has additional information and a video report on the Stereotaxis technology.