Impedance shift detection

Patent metadata

Field	Value
Publication number	US-10441192-B2
Application number	US-201715649839-A
Country	US
Kind code	B2
Filing date	Jul 14, 2017
Priority date	Jul 15, 2016
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

A pre-shift set of fiducials each including a pre-shift fiducial impedance location and a pre-shift fiducial magnetic location can be determined. The pre-shift fiducial impedance locations and the pre-shift fiducial magnetic location are associated with a medical device. A post-shift set of fiducials each including a post-shift fiducial impedance location and a post-shift fiducial magnetic location can be determined. The post-shift fiducial impedance locations and the post-shift fiducial magnetic locations are associated with the medical device. A pre-shift transformation can be fit to the pre-shift set of fiducials and a post-shift transformation can be fit to the post-shift set of fiducials. A determination can be made whether the pre-shift transformation differs from the post-shift transformation. An indication that an impedance shift has occurred between the pre-shift set of fiducials and the post-shift set of fiducials can be generated based on the difference between the pre-shift transformation and the post-shift transformation.

First claim

What is claimed:

1. A computer implemented method for detection of an impedance shift, comprising:
determining a pre-shift set of fiducials that includes for each fiducial a pre-shift fiducial impedance location and a pre-shift fiducial magnetic location, the pre-shift fiducial impedance locations and the pre-shift fiducial magnetic locations being associated with a medical device;
determining a post-shift set of fiducials that includes for each fiducial a post-shift fiducial impedance location and a post-shift fiducial magnetic location, the post-shift fiducial impedance locations and the post-shift fiducial magnetic locations being associated with the medical device;
fitting a pre-shift transformation to the pre-shift set of fiducials and a post-shift transformation to the post-shift set of fiducials;
determining that a distance, at a current location of the medical device, between the pre-shift transformation and the post-shift transformation exceeds a threshold distance;
determining a statistical confidence that the distance exceeds the threshold distance;
determining that the statistical confidence exceeds a threshold confidence;
determining that the impedance shift has occurred based on the distance exceeding the threshold distance and the statistical confidence exceeding the threshold confidence; and
generating an indication that the impedance shift has occurred.

2. The method of claim 1 , wherein the particular statistical confidence is user configurable.

3. The method of claim 1 , wherein the threshold distance is user configurable.

4. The method of claim 1 , wherein the pre-shift set of fiducials is collected during a pre-shift time period.

5. The method of claim 4 , wherein the pre-shift time period excludes a most recent time period.

6. The method of claim 1 , wherein the post-shift set of fiducials is collected during a post-shift time period.

7. The method of claim 6 , wherein the post-shift time period includes a time period that abuts a current time.

8. The method of claim 1 , wherein the pre-shift set of fiducials is filtered for bad status bits.

9. The method of claim 1 , wherein the pre-shift set of fiducials is gated for a particular respiratory phase.

10. The method of claim 1 , further comprising providing a notification of the impedance shift to a user via a user interface.

11. The method of claim 1 , further comprising determining a time at which the impedance shift has occurred.

12. The method of claim 11 , further comprising preventing an additional impedance shift from being reported within a defined time after the time at which the impedance shift has occurred.

13. A system for determining a detection of an impedance shift, comprising:
a computing device comprising processor resources and memory resources, the memory resources storing computer-readable instructions that, when executed by the processor resources, cause the processor resources to:
determine a pre-shift set of fiducials that includes for each fiducial a pre-shift fiducial impedance location and a pre-shift fiducial magnetic location, the pre-shift fiducial impedance locations and the pre-shift fiducial magnetic locations being associated with a medical device;
determine a post-shift set of fiducials that includes for each fiducial a post-shift fiducial impedance location and a post-shift fiducial magnetic location, the post-shift fiducial impedance locations and the post-shift fiducial magnetic locations being associated with the medical device;
fit a pre-shift transformation to the pre-shift set of fiducials and a post-shift transformation to the post-shift set of fiducials;
determine that a distance, at a current location of the medical device, between the pre-shift transformation and the post-shift transformation exceeds a threshold distance;
determine a statistical confidence that the distance exceeds the threshold distance;
determine that the statistical confidence exceeds a threshold confidence;
determine that an impedance shift has occurred, based on the distance exceeding the threshold distance and the statistical confidence exceeding the threshold confidence; and
generate the indication that the impedance shift has occurred.

14. The system of claim 13 , wherein the pre-shift set of fiducials associated with the medical device include a pre-shift fiducial impedance location and a pre-shift fiducial magnetic location.

15. The system of claim 13 , wherein the post-shift set of fiducials associated with the medical device include a post-shift fiducial impedance location and a post-shift fiducial magnetic location.

16. The system of claim 13 , wherein the current location of the medical device is determined based on a signal from a magnetic position sensor disposed on the medical device.

Assignees

• St Jude Medical Cardiology Div Inc

Inventors

• Thompson Cable
• Hill Anthony D

Classifications

• A61B2034/2053

  Tracking an applied voltage gradient · CPC title

• A61B2017/00725

  Calibration or performance testing · CPC title

• A61B2090/0812

  indicating loosening or shifting of parts of an instrument, signaling maladjustment of parts · CPC title

• A61B5/061 Primary

  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 title

• A61B2034/2051

  Electromagnetic tracking systems · CPC title