Determining a position of a member within a sheath

A system for determining a location of an instrument within an anatomy comprising:

• a first electrode patch in contact with the anatomy;
• a second electrode patch in contact with the anatomy and spaced apart from the first electrode patch;
• a first instrument navigable within the anatomy relative to the first electrode patch and the second electrode patch that defines at least one lumen, and includes a distal end;
• a second instrument received through the at least one lumen and navigable within the anatomy relative to the first instrument, the first electrode patch and the second electrode patch;
• at least one electrode coupled to the distal end of the first instrument, the at least one electrode responsive to electrical activity to generate at least one signal;
• a sensing unit in communication with the first electrode patch and the second electrode patch to generate voltages between the first electrode patch and the second electrode patch, the sensing unit in communication with the at least one electrode of the first instrument to receive the at least one signal and to determine at least one impedance of the at least one electrode of the first instrument based on the at least one signal;
• and
• a control module that determines, based on the at least one impedance of the at least one electrode of the first instrument, the location of the first instrument within the anatomy.

A method for determining a location of an instrument within an anatomy comprising:

• providing a first instrument that includes at least one lumen;
• inserting a second instrument into the at least one lumen;
• inserting the second instrument and at least a portion of the first instrument into the anatomy;
• sensing electrical activity within the anatomy near the portion of the first instrument;
• determining, based on the sensed electrical activity, the location of the first instrument;
• and
• slitting the at least one electrode to remove the first instrument from the anatomy without removing the second instrument.