Source: https://patents.google.com/patent/US8571647B2/en
Timestamp: 2019-05-23 02:05:11
Document Index: 668322732

Matched Legal Cases: ['art.\n9', 'art.\n34', 'art.\n35', 'art.\n41', 'art.\n47', 'art.\n59', 'art.\n61', 'art.\n66', 'art.\n73', 'art.\n75', 'art.\n80', 'art.\n83']

US8571647B2 - Impedance based anatomy generation - Google Patents
US8571647B2
US8571647B2 US12/437,812 US43781209A US8571647B2 US 8571647 B2 US8571647 B2 US 8571647B2 US 43781209 A US43781209 A US 43781209A US 8571647 B2 US8571647 B2 US 8571647B2
US12/437,812
US20100286551A1 (en
2009-05-08 Application filed by Rhythmia Medical Inc filed Critical Rhythmia Medical Inc
2009-06-11 Assigned to RHYTHMIA MEDICAL, INC. reassignment RHYTHMIA MEDICAL, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BADICS, ZSOLT, CSENDES, ALPAR, HARLEV, DORON
2010-03-16 Priority claimed from PCT/US2010/027436 external-priority patent/WO2010129095A2/en
2010-11-11 Publication of US20100286551A1 publication Critical patent/US20100286551A1/en
2013-10-29 Publication of US8571647B2 publication Critical patent/US8571647B2/en
Methods and systems for determining anatomical information based on signals measured by multiple, spatially distributed electrodes on a catheter are disclosed herein. In some examples, methods and systems disclosed herein can include causing current to flow between at least some of the electrodes, measuring an electrical signal at each of one or more measuring electrodes, and determining anatomical information based on the measured signals.
FIGS. 2 a-c show different views for one embodiment of the catheter 110, which includes a base sleeve 112, a central retractable inner member 114, and multiple splines 116 connected to base sleeve 112 at one end and inner member 114 at the other end. When inner member 114 is in an extended configuration (not shown), splines 116 are pulled tight to the inner member so that catheter 110 has a narrow profile for guiding it through blood vessels. When inner member 114 is retracted (as shown in FIGS. 2 a-b), splines 116 are deployed and pushed into an outward “olive” shaped configuration for use in the heart cavity. As explained in more detail below, the splines 116 each carry electrodes, so when the inner member is in the retracted configurations the electrode are deployed in the sense that they are distributed over a greater volume.
The MEA catheter is connected to electronics hardware capable of driving the necessary current and detecting both signals originating from the heart as well as those used for anatomy construction. There is a need to distinguish between the two signals in order to separate the signal being used for the anatomy determination from the cardiac signal. The CIE are therefore coupled to electronics injecting the current at a frequency higher than cardiac activation (cardiac activation <2 kHz, CIE>4 kHz, e.g. 5 kHz) such that the two types of signals can be easily distinguished using frequency analysis. It should be noted that other methods for distinguishing between the CIE signal and the cardiac activation signal can be used, such as injecting a spread-spectrum signal having a low energy level in the frequency range of the cardiac activation signal, and detecting this spread-spectrum signal in the signal collected by the all PME.
Instead of using an overly high number of degrees of freedom, in some embodiments the abrupt conductivity distribution is represented in a way that uses only a few parameters. For example, as shown in FIG. 5, this can be achieved by an explicit representation of a closed and parameterized local surface 276 around the catheter 278. This representation divides the 3D space into two regions 274 and 272. The region 274 in which the catheter 278 is located is associated with the conductivity of blood (Ωblood) while the outside region 272 is associated with an unknown conductivity (Ωexternal) since it varies from patient to patient and between different regions in the cardiac chamber. This local parameterized surface 276 and the conductivity values (Ωblood and Ωexternal) constitute a local forward model used in the inverse solver. This model aims to reconstruct the shape and value of the conductivity distribution. This inverse problem is nonlinear and requires the use of an iterative solver. The inverse solver is an optimizer that determines both the surface's parameters as well as the unknown external conductivity (Ωexternal). The choice of the local parameterized surface 276 is only limited by its number of parameters or degrees of freedom. For example, a fully parameterized 3D ellipsoid introduces nine degrees of freedom: three axial parameters and six parameters for rigid body translation and rotation. It is also possible to use polynomial representation, Bezier, NURBS or curvilinear finite elements to represent the parameterized surface 276. FIG. 6 shows a system and method for generation of a local parameterized surface including the measurement hardware 284 along with the inverse solver 290 (e.g., software) which reconstructs the local parameterized surface 276.
G ⁡ ( x , t , α ) = 1 1 + ⅇ α ⁡ ( x - t )
Where t and α are parameters of the membership function; t is the turn-point 306 and α determines the slope of the membership function at the turn-point 306.
The LM residual is expected to be smaller when the optimization is more successful and therefore the local parameterized surface is expected to approximate the chamber boundary better. For this reason, smaller values for the LM residual should produce higher confidence levels: one or close to one. Increasing residual, on the other hand, should eventually switch the corresponding confidence level down to zero. In order to establish what “small” is, the LM residual is normalized. This normalization is such that when the local forward model is the homogenous case, the corresponding normalized residual would be exactly one. In other words, the residual measures how much the distortion field is reconstructed by the optimized local forward model at the PME compared to the homogenous case, which is regarded as complete lack of reconstruction. The normalization described here is only the first step to make sure the membership function produces meaningful confidence levels. The missing additive is the parameter of the membership function itself, called turn-point. In some examples, for the LM residual a turn-point 306 of 0.05 is believed to be adequate. This is the normalized LM residual value, which produces confidence level of exactly one half. The appropriate a for this criteria is believed to be 80.
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
subsequent to causing current flow and measuring the electrical signals at the multiple, different catheter positions, determining anatomical information about the heart based on positions of the catheter electrodes at a plurality or the multiple, different catheter positions, the measured signals at the plurality of the multiple, different catheter positions, and a surface location threshold applied to a measure related to a distance between a surface of the heart and the catheter;
wherein determining the anatomical information based on the measured signals further compromise:
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.
2. The method of claim 1, wherein the determination of the anatomical information accounts for a change in conductivity at the cardiac chamber boundary.
3. The method of claim 2, wherein the determination accounts for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.
4. The method of claim 1, 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.
5. The method of claim 4, wherein the impedance information is based on a conductivity contrast between blood and surrounding tissue.
6. The method of claim 4, wherein the impedance information is based on a permittivity contrast between blood and surrounding tissue.
7. The method of claim 1, wherein determining the anatomical information compromises:
generating impedance information based on the measured signals at the different catheter positions, the impedance information comprising complex impedance information based on both a permittivity contrast and a conductivity contrast between blood and surrounding tissue; and
8. The method of claim 1, wherein the anatomical information comprises a representation of at least a portion of a boundary of the heart.
9. The method of claim 1, wherein determining the anatomical information comprises detecting a boundary of the heart and the method further comprises displaying at least a portion of the anatomical information.
10. The method of claim 1, wherein determining the anatomical information comprise, for each of the different catheter positions, determining a surface based on the measured signals, the surface representing a surface at which the conductivity changes.
11. The method of claim 10, wherein the surface comprises a closed and parameterized surface around at least a portion of the catheter.
12. The method of claim 11, wherein the surface comprises an ellipsoid.
13. The method of claim 11, wherein the surface comprises a curvilinear surface.
14. The method of claim 10, wherein the surface provides a boundary between a region represented by a first conductivity inside the surface and a region represented by a second conductivity outside the surface, the first conductivity being different from the second conductivity.
15. The method of claim 10, wherein determining the anatomical information further comprises, for each of the determined surfaces selecting one or more regions of the surface corresponding to a boundary of a portion of the heart the selection being based at least in part on the surface location threshold.
17. The method of claim 16, wherein the surface location threshold comprises a threshold based on a magnitude of a distortion field and selecting the one or more regions comprises selecting the one or more regions based at least in part on a magnitude of a distortion field, the distortion field being based at least in part on a difference between a field calculated based on the measurements and a field in a homogonous medium.
18. The method of claim 16, wherein selecting the one or more regions comprises selecting the one or more regions based at least in part on an error calculation in an optimization used to generate the surface.
19. The method of claim 16, wherein determining the anatomical information further comprises, joining the regions of the determined surfaces corresponding to an expected chamber boundary to generate the anatomical information; and the method further comprises displaying at least a portion of the anatomical information.
20. The Method of claim 19, wherein joining the regions comprises using a meshing algorithm.
21. The method of claim 1, further comprising using the multiple electrodes on the catheter to measure cardiac signals at the catheter electrodes in response to electrical activity in the heart.
determining physiological information at multiple locations of the boundary of the heart based on the determined positions of 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.
23. The method of claim 1, further comprising using one or more electrodes on the catheter for delivering ablation energy for ablating tissue.
24. The method of claim 1, further comprising displaying at least a portion of the anatomical information.
25. The method of claim 24, wherein displaying at least a portion of the anatomical information comprises displaying at least a portion of the boundary of the heart.
inserting a catheter into a heart, the catheter comprising multiple, spatially distributed electrodes including one or more measuring electrodes and multiple sets of current injecting electrodes each set of current injecting electrodes comprising at least a current source electrode and a current sink electrode;
for each of the multiple different sets of current injecting electrodes, causing current to flow between at least some of the electrodes and in response to current flow, measuring an electrical signal at the one or more measuring electrodes; and
determining anatomical information based on the measured signals and a surface location threshold applied to a measure related to a distance between a surface of the heart and the catheter.
27. The method of claim 26, wherein the determination of the anatomical information accounts for a change in conductivity at the cardiac chamber boundary.
28. The method of claim 27, wherein the determination accounts for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.
29. The method of claim 28, wherein determining the anatomical information comprises determining the anatomical information based at least in part on impedance information generated based on the measured signals.
30. The method of claim 29, wherein the impedance information is based on a conductivity contrast between blood and surrounding tissue.
31. The method of claim 29, wherein the impedance information is based on a permittivity contrast between blood and surrounding tissue.
32. The method of claim 29, wherein the impedance information comprises complex impedance information based on both a permittivity contrast and a conductivity contrast between blood and surrounding tissue.
33. The method of claim 26, wherein the anatomical information comprises a representation of at least a portion of a boundary of the heart.
34. The method of claim 26, wherein determining the anatomical information comprises detecting a boundary of the heart.
35. The method of claim 26, wherein determining the anatomical information comprises, determining a surface based on the measured signals, the surface representing a surface at which the conductivity value changes.
36. The method of claim 35, wherein the surface comprises a closed and parameterized surface around at least a portion of the catheter.
37. The method of claim 36, wherein the surface comprises an ellipsoid.
38. The method of claim 36, wherein the surface comprises a curvilinear surface.
39. The method of claim 35, wherein the surface provides a boundary between a region represented by a first conductivity inside the surface and a region represented by a second conductivity outside the surface, the first conductivity being different from the second conductivity.
40. The method of claim 35, wherein determining the anatomical information further comprises, for each of the determined surfaces selecting one or more regions of the surface corresponding to an expected boundary of the heart.
41. The method of claim 35, wherein selecting the or more regions comprises selecting the one or more regions based at least in part on a distance between a portion of the surface and the catheter.
42. The method of claim 41, wherein selecting the one or more regions comprises selecting the one or more regions based at least in part on a magnitude of a distortion field, the distortion field being based at least in part on a difference between a field calculated based on the measurements and a field in a homogonous medium.
43. The method of claim 41, wherein selecting the one or more regions comprises selecting the one or more regions based at least in part on an error calculation in an optimization used to generate the surface.
44. The method of claim 43, wherein determining the anatomical information further comprises, joining the regions of the determined surfaces corresponding at an expected chamber boundary to generate the anatomical information.
45. The method of claim 44, wherein joining the regions comprising using a meshing algorithm.
46. The method of claim 26, further comprising using the multiple electrodes on the catheter to measure cardiac signals at the catheter electrodes in response to electrical activity in the heart.
47. The method of claim 46, further comprising determining physiological information at multiple locations of the boundary of the heart based on positions of the catheter electrodes and the measured cardiac signals.
48. The method of claim 26, further comprising using one or more electrodes on the catheter for delivering ablation energy for ablating tissue.
49. The method of claim 26, wherein determining the anatomical information based on the measured signals from the one or more electrodes comprises distinguishing electrical signals indicative of cardiac electrical activity from those responsive to the injected current.
50. The method of claim 26, further comprising displaying at least a portion of the anatomical information.
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 at a plurality of the multiple, different catheter positions and measured electrical signals at the plurality of the multiple, different catheter positions subsequent to receiving information about the positions and measured electrical signals from the plurality of the multiple, different catheter positions, the measured signals at the plurality of the multiple, different catheter positions, and a surface location threshold applied to a measure related to a distance between a surface of the heart and the catheter.
52. The system of claim 51, wherein the processing unit is configured to account for a change in conductivity at a cardiac chamber boundary in the determination of the anatomical information.
53. The system of claim 52, wherein the processing unit is configured to account for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.
54. The system of claim 51, wherein the processing unit is configured to determine the anatomical information based at least in part on impedance information.
55. The system of claim 54, wherein the impedance information is based on a conductivity contrast between blood and surrounding tissue.
56. The system of claim 54, wherein the impedance information is based on a permittivity contrast between blood and surrounding tissue.
57. The system of claim 54, wherein the impedance information comprises complex impedance information based on both a permittivity contrast and a conductivity contrast between blood and surrounding tissue.
58. The system of claim 53, wherein the anatomical information comprises a representation of at least a portion of a boundary of the heart.
59. The system of claim 53, wherein the processing unit is configured to determine the anatomical information by determining a surface based on the measured signals, the surface representing a surface at which the conductivity changes.
60. The system of claim 59, wherein the processing unit is configured to, for each of the determined surfaces, select one or more regions of the surface corresponding to a boundary of a portion of the heart.
61. The system of claim 59, wherein the processing unit is configured to select the one or more regions based at least in part on a distance between a portion of the surface and the electrodes.
62. The system of claim 61, wherein the processing unit is configured to select the one or more regions based at least in part on a magnitude of a distortion field, the distortion field being based at least in part on a difference between a field calculated based on the measurements and a field in a homogonous medium.
63. The system of claim 61, wherein the processing unit is configured to select the one or more regions based at least in part on an error calculation in an optimization used to generate the surface.
64. The system of claim 61, wherein the processing unit is configured to join the regions of the determined surfaces corresponding to an expected chamber boundary to generate the anatomical information.
65. The system of claim 53, wherein the multiple electrodes are further configured to measure cardiac signals in response to electrical activity in the heart.
66. The system of 65, wherein the processing unit is configured to determine physiological information at multiple locations of the boundary of the heart based on positions of the catheter electrodes and measured cardiac signals.
67. The system comprising:
a catheter comprising multiple, spatially distributed electrodes including one or more measuring electrodes and multiple sets of current injecting electrodes each set of current injecting electrodes comprising at least a current source electrode and a current sink electrode, the current injecting electrodes being configured to inject a current and measuring electrodes being configured to measure electrical signals in response to the injected current; and
a processing unit configured to determine anatomical information about the heart based on the measured signals and a surface location threshold applied to a measure related to a distance between a surface of the heart and the catheter.
68. The system of claim 67, wherein the processing unit is configured to account for a change in conductivity at the cardiac chamber boundary in the determination of the anatomical information.
69. The system of claim 67, wherein the processing unit is configured to account for a first conductivity inside the cardiac chamber boundary and a second conductivity outside the cardiac chamber boundary.
70. The system of claim 67, wherein the processing unit is configured to determine the anatomical information based at least in part on impedance information generated based on the measured signals at the different catheter positions.
71. The system of claim 70, wherein the impedance information is based on a conductivity contrast between blood and surrounding tissue.
72. The system of claim 67, wherein the anatomical information comprises a representation of at least a portion of a boundary of the heart.
73. The system of claim 67, wherein the processing unit is configured to determine the anatomical information by determining a surface based on the measured signals, the surface representing a surface at which the conductivity changes.
74. The system of claim 73, wherein the processing unit is configured to, for each of the determined surfaces, select one or more regions of the surface corresponding to a boundary of a portion of the heart.
75. The system of claim 73, wherein the processing unit is configured to select the one or more regions based at least in part on a distance between a portion of the surface and the catheter.
76. The system of claim 75, wherein the processing unit is configured to select the one or more regions based at least in part on a magnitude of a distortion field, the distortion field being based at least in part on a difference between a field calculated based on the measurements and a field in a homogonous medium.
77. The system of claim 76, wherein the processing unit is configured to select the one or more regions based at least in part on an error calculation in an optimization used to generate the surface.
78. The system of claim 76, wherein the processing unit is configured to select the regions of the determined surfaces corresponding to an expected chamber boundary to generate the anatomical information.
79. The system of claim 67, wherein the electrodes on the catheter are the further configured to measure cardiac signals in response to electrical activity in the heart.
80. The system of claim 79, wherein the processing unit is 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.
81. The method of claim 1, wherein determining the anatomical information comprises:
for each Of the different catheter positions, determining a surface based on the measured signals, the surface representing a boundary between a region represented by a first conductivity inside the surface and a region represented by a second conductivity outside the surface, the first conductivity being different from the second conductivity;
for each of the determined surfaces selecting one or more regions of the surface corresponding to a boundary of a portion of the heart; and
joining the regions of the determined surfaces corresponding to an expected chamber boundary to generate the anatomical information.
82. The method of claim 1, Wherein determining the anatomical information comprises, for each of the different catheter positions, determining a surface based on the measured signals and selecting one or more regions of the surface corresponding to a boundary of a portion of the heart.
83. The method of claim 1, wherein the surface location threshold comprises a threshold based on a distortion field strength.
84. The method of claim 1, wherein the surface location threshold comprises a threshold based on a distance of the surface location from the center of the catheter.
85. The method of claim 1, wherein the surface location threshold comprises a threshold based at least in part on a residual error of an optimization.
US12/437,812 2009-05-08 2009-05-08 Impedance based anatomy generation Active 2030-10-15 US8571647B2 (en)
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EP10772414.8A EP2427106B1 (en) 2009-05-08 2010-03-16 Impedance based anatomy generation
US20100286551A1 US20100286551A1 (en) 2010-11-11
US8571647B2 true US8571647B2 (en) 2013-10-29
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HARLEV, DORON;CSENDES, ALPAR;BADICS, ZSOLT;REEL/FRAME:022817/0675