Dynamic adaptive respiration compensation with automatic gain control

• US 9,113,807 B2
• Filed: 12/29/2010
• Issued: 08/25/2015
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Original Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Inventors: Koyrakh, Lev A., Voth, Eric J., Hauck, John A., Schweitzer, Jeffrey A.
• Primary Examiner(s): Fernandez, Katherine
• Assistant Examiner(s): KELLOGG, MICHAEL S
• Application Number:
  US12/980,515
• Publication Number:
  US 20120172702A1
• Time in Patent Office: 1,700 Days
• Field of Search: 600/408, 600/424
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0044 for the heart
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0536 Impedance imaging, e.g. by tomography
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/063 using impedance measurements
• CPC Class Codes: A61B 5/6801 specially adapted to be attached to or worn on the body surface
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7267 involving training the classification device
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: H04L 25/0278 Arrangements for impedance matching

Abstract

A system for determining a location of an electrode of a medical device (e.g., a catheter) in a body of a patient includes a localization block for producing an uncompensated electrode location, a motion compensation block for producing a compensation signal (i.e., for respiration, cardiac, etc.), and a mechanism for subtracting the compensation signal from the uncompensated electrode location. The result is a corrected electrode location substantially free of respiration and cardiac artifacts. The motion compensation block includes a dynamic adaptation feature which accounts for changes in a patient'"'"'s respiration patterns as well as intentional movements of the medical device to different locations within the patient'"'"'s body. The system further includes an automatic compensation gain control which suppresses compensation when certain conditions, such as noise or sudden patch impedance changes, are detected.

Claims

1. A method for determining a motion compensated location of an electrode of a medical device within a body of a patient, comprising the steps of:

(A) acquiring (i) patch electrode impedance data using associated body surface electrodes and (ii) electrode location data using said electrode of said medical device;

(B) mean-adjusting, using a computer system, the patch electrode impedance data associated with body surface electrodes and the electrode location data associated with said electrode;

(C) determining, using the computer system, an acquired set of weights such that a linear combination of the product of the weights and mean-adjusted patch impedance data correspond to the mean-adjusted electrode location data;

(D) repeating steps (A), (B), and (C) for a plurality of different time periods and producing a plurality of sets of weights, and as each successive acquired sets of weights is determined in step (C),

(i) determining, using the computer system, a learning parameter based on a distance between successive, acquired sets of weights,

(ii) updating, using the computer system, a reference set of weights based on the determined learning parameter;

(E) determining, using the computer system, a compensation signal using the reference set of weights and patch electrode impedance data wherein the compensation signal corresponds to motion artifacts associated with an uncompensated electrode location and wherein the compensation signal is configured to reduce such motion artifacts associated with the uncompensated electrode location;

(F) computing, using the computer system, the motion compensated electrode location using the uncompensated electrode location and the compensation signal; and

(G) generating a visual representation of the medical device on a display based on the motion compensated electrode location.

2. The method of claim 1 wherein said motion compensated electrode location includes one of a position and orientation (P&

O) in a reference coordinate system, said method further including the step of selecting one or more axes for compensation, said step of determining a set of weights being further performed for each selected axis.

3. The method of claim 1 wherein said step of determining a set of weights involves principal component analysis (PCA).

4. The method of claim 1 wherein said mean-adjusted patch data and electrode location data are in matrix form, said step of determining a set of weights includes the sub-steps of:

performing singular value decomposition of the mean-adjusted patch data matrix;

obtaining the pseudo-inverse of the mean-adjusted patch data matrix and applying regularization;

determining said set of weights in accordance with the product of the pseudo-inverse mean-adjusted patch data matrix and the electrode location data matrix.

5. The method of claim 3 wherein updating a reference set of weights includes:

determining a difference between a most-recent acquired set of weights and the current reference set of weights;

determining a product of the learning parameter and the difference; and

summing the current reference set of weights and the product.

6. The method of claim 5 wherein the learning parameter is equal to or greater than zero and equal to or less than one.

7. The method of claim 5 further including the steps of:

varying the learning parameter in accordance with the distance between successive, acquired sets of weights.

8. The method of claim 7 wherein said step of varying the learning parameter includes the sub-step of:

exponentially reducing the learning parameter as a function of the distance between successive, acquired sets of weights.

9. The method of claim 1 wherein said step of determining a compensation signal involves automatically controlling a gain parameter.

10. The method of claim 9 further including the step of setting the gain parameter to a default value of 1.

11. The method of claim 10 further including the steps of:

determining a moving average of the compensation signal;

determining an average deviation of the compensation signal from the moving average;

determining a current deviation between a current value of the compensation signal and the moving average;

reducing the default value of the gain parameter in accordance with the ratio between the average deviation and the current deviation when the current deviation exceeds a deviation threshold.

12. The method of claim 11 wherein said motion compensated electrode location includes one of a position and orientation (P&

O) in a reference coordinate system, said method further including the step of selecting one or more axes in the coordinate system for compensation, said gain parameter having respective values for each one of said selected axes.

13. The method of claim 1 wherein the electrode is a first electrode and the motion compensated electrode location is a motion compensated first electrode location having associated therewith a coordinate within a reference coordinate system, the method further including the steps of:

determining an uncompensated second electrode location associated with a second electrode; and

applying the compensation signal to the uncompensated second electrode location to produce a motion compensated second electrode location when the uncompensated second electrode location matches the coordinate within a predetermined range.

15. The method of claim 1 wherein the motion artifacts comprise at least one of respiration-induced motion artifacts and cardiac motion artifacts.

17. The method of claim 1 wherein the computer system includes program instructions for determining the motion compensated location of the electrode of the medical device within the body of the patient and wherein execution of the program instructions by one or more processors in the computer system causes the one or more processors to carry out the steps (B)-(G).

14. A method for determining a motion compensated location of magnetic field sensor of a medical device within a body of a patient, comprising the steps of:

(A) acquiring (i) patch electrode impedance data using associated body surface electrodes and (ii) magnetic sensor location data using said magnetic field sensor;

(B) mean-adjusting, using a computer system, the patch electrode impedance data associated with body surface electrodes and the magnetic sensor location data associated with said magnetic field sensor;

(C) determining, using the computer system, an acquired set of weights such that a linear combination of the product of the weights and mean-adjusted patch impedance data correspond to the mean-adjusted magnetic sensor location data;

(D) repeating steps (A), (B), and (C) for a plurality of different time periods and producing a plurality of sets of weights, and as each successive acquired sets of weights is determined in step (C),

(i) determining, using the computer system, a learning parameter based on a distance between successive, acquired sets of weights,

(ii) updating, using the computer system, a reference set of weights based on the determined learning parameter;

(E) determining, using the computer system, a compensation signal using the reference set of weights and patch electrode impedance data wherein the compensation signal corresponds to motion artifacts associated with an uncompensated magnetic field sensor location and wherein the compensation signal is configured to reduce such motion artifacts associated with the uncompensated magnetic field sensor location;

(F) computing, using the computer system, the motion compensated magnetic field sensor location using the uncompensated magnetic field sensor location and the compensation signal; and

(G) generating a visual representation of the medical device on a display based on the compensated magnetic field sensor location.

16. The method of claim 14 wherein the motion artifacts comprise at least one of respiration-induced motion artifacts and cardiac motion artifacts.

18. A method for determining a motion compensated location of a first electrode of a medical device within a body of a patient, comprising the steps of:

(A) acquiring (i) patch electrode impedance data using associated body surface electrodes and (ii) first electrode location data using said first electrode of said medical device;

(B) mean-adjusting, using a computer system, the patch electrode impedance data associated with body surface electrodes and the first electrode location data associated with said electrode;

(C) determining, using the computer system, an acquired set of weights such that a linear combination of the product of the weights and mean-adjusted patch impedance data correspond to the mean-adjusted first electrode location data;

(D) repeating steps (A), (B), and (C) for a plurality of different time periods and producing a plurality of sets of weights, and as each successive acquired sets of weights is determined in step (C),

(i) determining, using the computer system, a learning parameter based on a distance between successive, acquired sets of weights,

(ii) updating, using the computer system, a reference set of weights based on the determined learning parameter;

(E) determining, using the computer system, a compensation signal using the reference set of weights and patch electrode impedance data wherein the compensation signal corresponds to motion artifacts associated with an uncompensated first electrode location and wherein the compensation signal is configured to reduce such motion artifacts associated with the uncompensated first electrode location;

(F) computing, using the computer system, the motion compensated first electrode location using the uncompensated first electrode location and the compensation signal;

G) displaying a representation of the medical device on a display based on the compensated first electrode location; and

H) positioning a second electrode of the medical device within the body based on the representation of the medical device, wherein the second electrode is configured to act on the patient to perform at least one of a diagnostic procedure and therapeutic procedure.