CATHETER WITH ELECTRODES FOR IMPEDANCE AND/OR CONDUCTION VELOCITY MEASUREMENT

• US 20090177069A1
• Filed: 01/05/2009
• Published: 07/09/2009
• Est. Priority Date: 01/04/2008
• Status: Active Grant

• Current Assignee: Texas Heart Institute
• Original Assignee: Texas Heart Institute
• Inventors: RAZAVI, Mehdi
• Granted Patent: US 8,961,417 B2
• Time in Patent Office: Days
• US Class Current: 600/371
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/283 Invasive

Abstract

An apparatus comprises a catheter comprising a first electrode. The apparatus also comprises a second electrode electrically attached to a person and coupled to the first electrode via the person'"'"'s tissue. Logic is coupled to the electrodes and generates an electrical signal that is provided through the electrodes and computes an impedance or conduction velocity associated with the electrodes based on the electrical signal. The logic stores a threshold against which said computed impedance or conduction velocity is compared by said logic

Claims

1. An apparatus, comprising:

a catheter comprising a first electrode;

a second electrode electrically attached to a person and coupled to said first electrode via the person'"'"'s tissue; and

logic coupled to said electrodes, said logic generates an electrical signal that is provided through said electrodes and computes an impedance or conduction velocity associated with said electrodes based on said electrical signal;

wherein said logic stores a threshold against which said computed impedance or conduction velocity is compared by said logic.

2. The apparatus of claim 1 comprising a third electrode and said logic computes impedances between said first and third electrodes and said second and third electrodes, said logic also stores separate thresholds against which said impedances are compared.

3. The apparatus of claim 2 wherein the logic implements a calibration mode in which said thresholds are determined, said calibration mode initiated before a medical procedure is begun.

4. The apparatus of claim 3 wherein, while in the calibration mode, the logic determines an impedance between each pair of the first, second, and third electrodes.

5. The apparatus of claim 1 wherein the logic implements a calibration mode in which said threshold is determined, said calibration mode initiated before a medical procedure is begun.

6. The apparatus of claim 1 wherein the threshold comprises an impedance amplitude value.

7. The apparatus of claim 1 wherein the threshold comprises an impedance phase value.

8. The apparatus of claim 1 wherein the threshold comprises an impedance phase value and an impedance amplitude value.

9. The apparatus of claim 1 wherein said logic computes said impedance with the catheter inserted into the coronary sinus of the person.

10. The apparatus of claim 1 wherein the second electrode is at a site selected from a group consisting of the person'"'"'s skin, the person'"'"'s esophagus, and the person'"'"'s heart.

11. A method, comprising:

coupling a first electrode to a person;

coupling a second electrode to the person;

injecting, by a current source, an electrical current that runs through said electrodes;

computing, by logic, an impedance or conduction velocity based on said injected current; and

determining, by said logic, whether said impedance or conduction velocity is at a level indicative of bleeding or a clot;

wherein the first and second electrodes, respectively, are placed at sites selected from a group consisting of coronary sinus and esophagus, heart and esophagus, skin and esophagus, coronary sinus and skin, heart and skin, skin and skin, femoral artery and skin, guide wire and skin.

12. The method of claim 11 wherein determining, by said logic, whether said impedance is at a level indicative of bleeding comprises determining whether the impedance is at a level indicative of pericardial effusion or a hemothorax.

13. The method of claim 11 further comprising performing a calibration in which a threshold is computed for impedance between said first and second electrodes.

14. The method of claim 13 wherein the computed threshold comprises a phase threshold.

15. The method of claim 13 wherein the computed threshold comprises a phase threshold and an amplitude threshold.

16. The method of claim 11 further comprising coupling a third electrode to the person and computing impedance associated with said first and third electrodes and said second and third electrodes.

17. The method of claim 16 further comprising determining a threshold for the impedance computed for the first and second electrodes, the first and third electrodes, and the second and third electrodes.

18. An apparatus, comprising:

a catheter comprising a first electrode;

a second electrode electrically attached to a person and coupled to said first electrode via the person'"'"'s tissue; and

a signal generator coupled to said electrodes, said signal generator generates an electrical signal that is provided through said electrodes and computes an impedance associated with said electrodes based on said electrical signal.

19. The apparatus of claim 18 wherein the signal generator annunciates an alert if the computed impedance devices from a target impedance.

20. The apparatus of claim 18 wherein the catheter comprises a plurality of electrodes which are selectable by the signal generator to compute impedance.