Correction of shift and drift in impedance-based medical device navigation using measured impedances at external patch electrodes

An article of manufacture, comprising:

• a computer readable storage medium having a computer program encoded thereon that, when executed by an electronic control unit, determines one or more characteristics of a device electrode disposed on a medical device within a body, the computer program including code for:
• causing transmission of a current between a first pair of active electrodes, said first pair of active electrodes selected from among a plurality of measurements electrodes each coupled to an external surface of said body, to thereby generate a first voltage on said device electrode;
• receiving impedance signals from a plurality of passive electrodes, each of said passive electrodes comprising one of said plurality of measurement electrodes other than one of said first pair of active electrodes, each of said impedance signals indicative of an impedance at one of said plurality of passive electrodes;
• establishing a virtual reference electrode at a reference position within said body responsive to said impedance signals;
• generating a position value responsive to said first voltage on said device electrode and said reference position of said reference electrode;
• and,
• scaling said position value using a scaling value computed in response to said impedance signals.

A method for determining one or more characteristics of a device electrode disposed on a medical device within a body, the method comprising:

• causing transmission of a current between a first pair of active electrodes, said first pair of active electrodes selected from among a plurality of measurements electrodes each coupled to an external surface of said body, to thereby generate a first voltage on said device electrode;
• receiving impedance signals from a plurality of passive electrodes, each of said passive electrodes comprising one of said plurality of measurement electrodes other than one of said first pair of active electrodes, each of said impedance signals indicative of an impedance at one of said plurality of passive electrodes;
• establishing a virtual reference electrode at a reference position within said body responsive to said impedance signals;
• generating a position value responsive to said first voltage on said device electrode and said reference position of said reference electrode;
• and,
• scaling said position value using a scaling value computed in response to said impedance signals.