A magnetically navigable
catheter includes a sheath having a proximal end and a distal end, and an extension member having a proximal end and a distal end, slidably mounted in the sheath so that the distal end portion of the extension member telescopes from the distal end of the sheath. The distal end portion of the extension member being relatively more flexible than the distal end of the sheath. There may be one or more electrodes on the distal end of the extension member. There is also at least one
magnet, and preferably more than one
magnet, on the distal end portion of the extension member to allow the distal end of extension member to be oriented by the application of an externally applied
magnetic field. The
catheter preferably also includes a sleeve, having a proximal end and a distal end, the sleeve being slidably mounted in the sheath so that the distal end portion of the sleeve telescopes from the distal end of the sheath, so that the sleeve can be selectively extended and retracted relative to the sheath, and the extension member can be selectively extended and retracted relative to the sleeve. According to the method of this invention, the distal end of the
electrode catheter is introduced into the part of the body where the
electrode will be used to contact the specific body structures, and the
electrode is moved into contact with the body structure by applying an external
magnetic field and selectively telescoping the extension member relative to the sheath to bring the electrode on the distal end of the extension member into contact with the specific body structure.