Relative impedance measurement
AssigneeBiosense Webster, Inc.
InventorDaniel Osadchy
Life of this patent
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Abstract
A method for calibrating impedance includes coupling at least first, second, and third electrodes at respective locations to a surface of a body of a subject. A first current passing through the body between the first and second body-surface electrodes is measured, and a second current passing through the body between the first and third body-surface electrodes is measured. From the first and second currents, a contact factor is derived that is indicative of the impedance between at least one of the body-surface electrodes and the surface of the body. Also described are methods for sensing the position of a probe and for detecting tissue contact based on a relation between currents from the probe to body-surface electrodes.
Claims6
A method for position sensing, comprising:
- inserting a probe comprising a probe electrode into a body of a subject;
- measuring a first current passing through the body between the probe electrode and a first body-surface electrode coupled to a surface of the body;
- measuring a second current passing through the body between the probe electrode and a second body-surface electrode coupled to the surface of the body;
- calculating a relation between the first and second currents, the relation being indicative of a value of relative impedance between the probe electrode and each of the body-surface electrodes, and being based on a quotient of the first current and a sum of the first and second currents;
- and
- tracking movement of the probe within the body responsively to the relation.
Apparatus for position sensing, comprising:
- a probe, comprising a probe electrode, adapted to be inserted into a body of a subject;
- a first body-surface electrode and a second body-surface electrode, each adapted to be coupled at respective locations to a surface of the body;
- and
- a control unit, adapted to measure a first current passing through the body between the probe electrode and the first body-surface electrode, to measure a second current passing through the body between the probe electrode and the second body-surface electrode, to calculate a relation between the first and second currents, and to track movement of the probe within the body responsively to the relation,
- wherein the relation is indicative of a value of relative impedance between the probe electrode and each of the body-surface electrodes, and is based on a quotient of the first current and a sum of the first and second currents.
Dependencies are inferred from the claim text.