A medical instrument includes a flexible catheter and a catheter accessorydevice. Thecatheter has a distal end insertable within a body lumen of a patient. Thedevice isslidably engagable with the catheter. One of the catheter and the deviceincludesmagnetic material, and the other of the catheter and the device includeselectrically-energizablewindings. The catheter and the device are adapted to operate as a linearmotor wherein controllably electrically energizing the windings whileimmobilizing oneof the catheter and the device slidingly moves the other of the catheter andthe device. Amethod for using the medical instrument, wherein the medical instrument alsoincludes acontroller operatively connected to the windings, includes inserting thedistal end withinthe body lumen, immobilizing one of the catheter and the device, andactivating thecontroller to advance the other of the catheter and the device within the bodylumen.
