Impedance based anatomy generation

1. A method comprising:

inserting a catheter into a heart, the catheter comprising three or more electrodes;

causing the catheter to move to each of multiple, different positions in the heart;

for each of the multiple, different catheter positions, causing current to flow between at least some of the electrodes and in response to current flow, measuring an electrical signal at each of one or more of the electrodes; and

applying a threshold to the measured signals to select a subset of the electrode positions based on a measure indicative of a strength of influence of the cardiac chamber boundary on the measured signals; and

generating anatomical information about the heart based on positions of the catheter electrodes and the electrical signals from the electrodes at the determined subset of electrode positions.

2. The method of claim 1 , further comprising displaying at least a portion of the anatomical information.

3. The method of claim 2 , wherein displaying the at least a portion of the anatomical information comprises:

displaying a surface based on measured electrical signals from each of the multiple, different catheter positions; and

displaying a visual indicia on portions of the surface, the visual indicia being indicative of a location of a cardiac wall based and determined using the determined subset of electrode positions.

4. The method of claim 1 , wherein the measure indicative of the strength of influence of the cardiac chamber boundary comprises a measure based on field values in the presence of the inhomogeneous medium and expected field measurements in a homogeneous medium.

5. The method of claim 1 , further comprising:

determining physiological information at multiple locations of the boundary of the heart based on the determined positions of the catheter electrodes and measured cardiac signals at the different catheter positions; and

displaying at least a portion of the anatomical information and at least a portion of the physiological information, wherein generating the anatomical information comprises:

distinguishing electrical signals indicative of cardiac electrical activity from those responsive to the injected current; and

determining the anatomical information based on the electrical signals responsive to the injected current.

6. The method of claim 1 , wherein applying the threshold to the measured signals comprises calculating a magnitude of a distortion field and applying the threshold to the calculated magnitude of the distortion field.

7. The method of claim 1 , wherein the generation of the anatomical information accounts for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.

8. The method of claim 1 , wherein generating the anatomical information comprises:

generating impedance information based on the measured signals at the different catheter positions; and

determining the anatomical information based at least in part on the impedance information, the impedance information being based on a conductivity or permittivity contrast between blood and surrounding tissue.

9. The method of claim 1 , wherein generating the anatomical information comprises detecting a boundary of the heart by detecting a surface at which the conductivity changes; and the method further comprises displaying at least a portion of the anatomical information.

10. A method comprising:

inserting a catheter into a heart, the catheter comprising three or more electrodes;

causing the catheter to move to each of multiple, different positions in the heart;

for each of the multiple, different catheter positions, causing current to flow between at least some of the electrodes and in response to current flow, measuring an electrical signal at each of one or more of the electrodes; and

determining anatomical information about the heart based on positions of the catheter electrodes and a comparison between an expected field in a homogenous medium and the measured electrical signals.

11. The method of claim 10 , wherein the determination accounts for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.

12. The method of claim 10 , wherein determining the anatomical information comprises:

generating impedance information based on the measured signals at the different catheter positions; and

determining the anatomical information based at least in part on the impedance information, the impedance information being based on a conductivity or permittivity contrast between blood and surrounding tissue.

13. The method of claim 10 , wherein determining the anatomical information comprises detecting a boundary of the heart by detecting a surface at which the conductivity changes; and the method further comprises displaying at least a portion of the anatomical information.

14. The method of claim 10 , further comprising:

determining physiological information at multiple locations of the boundary of the heart based on the determined positions of the catheter electrodes and the measured cardiac signals at the different catheter positions; and

displaying at least a portion of the anatomical information and at least a portion of the physiological information, wherein determining the anatomical information comprises:

distinguishing electrical signals indicative of cardiac electrical activity from those responsive to the injected current; and

determining the anatomical information based on the electrical signals responsive to the injected current.

15. A method comprising:

inserting a catheter into a heart, the catheter comprising three or more electrodes;

causing the catheter to move to each of multiple, different positions in the heart;

for each of the multiple, different catheter positions, causing current to flow between at least some of the electrodes and in response to current flow, measuring an electrical signal at each of one or more of the electrodes; and

generating anatomical information about the heart by detecting variations in the measured signals based on an inhomogeneous distribution of material due to anatomical features of the heart.

16. The method of claim 15 , wherein the generation of the anatomical information accounts for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.

17. The method of claim 15 , wherein generating the anatomical information comprises:

generating impedance information based on the measured signals at the different catheter positions; and

determining the anatomical information based at least in part on the impedance information, the impedance information being based on a conductivity or permittivity contrast between blood and surrounding tissue.

18. The method of claim 15 , wherein generating the anatomical information comprises detecting a boundary of the heart by detecting a surface at which the conductivity changes; and the method further comprises displaying at least a portion of the anatomical information.

19. The method of claim 15 , further comprising:

determining physiological information at multiple locations of the boundary of the heart based on the determined positions of the catheter electrodes and the measured cardiac signals at the different catheter positions; and

displaying at least a portion of the anatomical information and at least a portion of the physiological information, wherein generating the anatomical information comprises:

distinguishing electrical signals indicative of cardiac electrical activity from those responsive to the injected current; and

determining the anatomical information based on the electrical signals responsive to the injected current.

20. A system comprising:

a catheter comprising multiple, spatially distributed electrodes including one or more electrodes configured to inject a current and to measure electrical signals in response to the injected current;

a system configured to determine a position of the catheter electrodes at multiple, different catheter positions; and

a processing unit configured to apply a threshold to the measured signals to select a subset of the electrode positions based on a measure indicative of a strength of influence of the cardiac chamber boundary on the measured signals and generate anatomical information about the heart based on positions of the catheter electrodes and the signals from the electrodes at the determined subset of electrode positions.

21. The system of claim 20 , wherein the processing unit is further configured to send information to cause a display device to display at least a portion of the anatomical information.

22. The method of claim 21 , wherein configurations to cause the processing unit to send information to cause a display device to display at least a portion of the anatomical information comprise configurations to cause the processing device to send information to cause the display device to:

display a surface based on measured electrical signals from each of the multiple, different catheter positions; and

display a visual indicia on portions of the surface, the visual indicia being indicative of a location of a cardiac wall based and determined using the determined subset of electrode positions.

23. The system of claim 20 , wherein the measure indicative of the strength of influence of the cardiac chamber boundary comprises a measure based on field values in the presence of the inhomogeneous medium and expected field measurements in a homogeneous medium.

24. The system of claim 20 , wherein the processing unit is configured to apply the threshold by calculating a magnitude of a distortion field and applying the threshold to the calculated magnitude of the distortion field.

25. The system of claim 20 , wherein the processing unit is configured to generate the anatomical information by:

generating impedance information based on the measured signals at the different catheter positions; and

determining the anatomical information based at least in part on the impedance information, the impedance information being based on a conductivity or permittivity contrast between blood and surrounding tissue.

26. The system of claim 20 , wherein the processing unit is configured to generate the anatomical information by detecting a boundary of the heart by detecting a surface at which the conductivity changes; and the processing unit is further configured to send a signal to cause a display unit to display at least a portion of the anatomical information.

27. The system of claim 20 , wherein the processing unit is further configured to:

determine physiological information at multiple locations of the boundary of the heart based on the determined positions of the catheter electrodes and the measured cardiac signals at the different catheter positions; and

display at least a portion of the anatomical information and at least a portion of the physiological information, wherein the configurations to generate the anatomical information comprise configurations to:

distinguish electrical signals indicative of cardiac electrical activity from those responsive to the injected current; and

determine the anatomical information based on the electrical signals responsive to the injected current.

28. A system comprising:

a catheter comprising multiple, spatially distributed electrodes including one or more electrodes configured to inject a current and to measure electrical signals in response to the injected current;

a system configured to determine a position of the catheter electrodes at multiple, different catheter positions; and

a processing unit configured to determine anatomical information about the heart based on positions of the catheter electrodes and a difference between an expected field in a homogenous medium and the measured electrical signals.

29. The system of claim 28 , wherein the processing unit is configured to determine the anatomical information by:

generating impedance information based on the measured signals at the different catheter positions; and

determining the anatomical information based at least in part on the impedance information, the impedance information being based on a conductivity or permittivity contrast between blood and surrounding tissue.

30. The system of claim 28 , wherein the processing unit is configured to determine the anatomical information by detecting a boundary of the heart by detecting a surface at which the conductivity changes; and the processing unit is further configured to send a signal to cause a display unit to display at least a portion of the anatomical information.

31. The system of claim 28 , wherein the processing unit is further configured to:

determine physiological information at multiple locations of the boundary of the heart based on the determined positions of the catheter electrodes and the measured cardiac signals at the different catheter positions; and

display at least a portion of the anatomical information and at least a portion of the physiological information, wherein the configurations to generate the anatomical information comprise configurations to:

distinguish electrical signals indicative of cardiac electrical activity from those responsive to the injected current; and

determine the anatomical information based on the electrical signals responsive to the injected current.

32. A system comprising:

a catheter comprising multiple, spatially distributed electrodes including one or more electrodes configured to inject a current and to measure electrical signals in response to the injected current;

a system configured to determine a position of the catheter electrodes at multiple, different catheter positions; and

a processing unit configured to generate anatomical information about the heart by detecting variations in the measured signals based on an inhomogeneous distribution of material due to anatomical features of the heart.

33. The system of claim 31 , wherein the processing unit is configured to generate the anatomical information by:

generating impedance information based on the measured signals at the different catheter positions; and

determining the anatomical information based at least in part on the impedance information, the impedance information being based on a conductivity or permittivity contrast between blood and surrounding tissue.

34. The system of claim 31 , wherein the processing unit is configured to generate the anatomical information by detecting a boundary of the heart by detecting a surface at which the conductivity changes; and the processing unit is further configured to send a signal to cause a display unit to display at least a portion of the anatomical information.

35. The system of claim 31 , wherein the processing unit is further configured to:

determine physiological information at multiple locations of the boundary of the heart based on the determined positions of the catheter electrodes and the measured cardiac signals at the different catheter positions; and

display at least a portion of the anatomical information and at least a portion of the physiological information, wherein the configurations to generate the anatomical information comprise configurations to:

distinguish electrical signals indicative of cardiac electrical activity from those responsive to the injected current; and

determine the anatomical information based on the electrical signals responsive to the injected current.