Impedance-based navigation of sheath

An impedance-based tracking system, comprising:

• a guiding sheath comprising a first tubular shaft comprising a lumen therethrough and a predetermined tubular wall region disposed approximate a distal end of the first tubular shaft, the predetermined tubular wall region configured to provide an electrically conductive path through the predetermined tubular wall region between the lumen of the first tubular shaft and an external environment to the first tubular shaft, the predetermined tubular wall region adjacent a second tubular wall region of the guiding sheath that is longer in length along a longitudinal axis of the guiding sheath than the predetermined tubular wall region;
• a medical probe comprising a second tubular shaft configured to be translated through the lumen of the first tubular shaft and comprising a tracking electrode coupled to the second tubular shaft, the second tubular wall region comprising a higher electrical impedance than the predetermined tubular wall region such that electrical current more readily passes radially through the predetermined tubular wall region for impedance-based tracking of the tracking electrode when the tracking electrode is in axial alignment with the predetermined tubular wall region than when the tracking electrode is out of axial alignment with the predetermined tubular wall region;
• a plurality of body patch electrodes configured to be in contact with skin of a patient;
• and
• a control unit configured to determine a position of the predetermined tubular wall region based at least in part on electrical signals between the tracking electrode and the plurality of body patch electrodes.