Implantable medical device systems having initialization functions and methods of operation

• US 20070276452A1
• Filed: 05/26/2006
• Published: 11/29/2007
• Est. Priority Date: 05/26/2006
• Status: Abandoned Application

• Current Assignee: Cameron Incorporated (Schlumberger NV)
• Original Assignee: Cameron Incorporated (Schlumberger NV)
• Inventors: Sanghera, Rick, Allavatam, Venugopal
• Application Number:
  US11/442,228
• Publication Number:
  US 20070276452A1
• Time in Patent Office: Days
• US Class Current: 607/59
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

Methods and devices for sensing vector analysis in an implantable cardiac stimulus system. In an illustrative example, a first sensing vector is analyzed to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis. If so, the first vector may be selected for detection and analysis. Otherwise, one or more additional vectors are analyzed. A detailed example illustrates methods for analyzing sensing vectors by the use of a scoring system. Devices adapted to perform these methods are also discussed, including implantable medical devices adapted to perform these methods, and systems comprising implantable medical devices and programmers adapted to communicate with implantable medical devices, the systems also being adapted to perform these methods. Another example includes a programmer configured to perform these methods including certain steps of directing operation of an associated implanted or implantable medical device.

Claims

1. A method of operating an implantable cardiac stimulus system comprising operational circuitry coupled to a plurality of sensing electrodes disposed within a patient and defining a plurality of sensing vectors for performing cardiac event detection, the method comprising:

the operational circuitry analyzing at least one of the plurality of sensing vectors; and

the operational circuitry either;

determining that an identified sensing vector is suitable for cardiac event detection;

or

determining that operator input is needed to complete a sensing vector selection process.

2. The method of claim 1, wherein the step of determining that operator input is needed to complete a sensing vector selection process is a step of last resort used when the operational circuitry cannot resolve or eliminate ambiguity in the analyzing step.

3. The method of claim 1, wherein the operator input is an indication of whether a T-wave component or a QRS-complex component of a cardiac signal, each captured using the same sensing vector, has a greater amplitude.

4. The method of claim 1, wherein the operator input is an indication of whether a desired cardiac component of cardiac signal or a noise artifact, each using captured the same sensing vector, has a greater amplitude.

5. The method of claim 1, wherein the step of determining that operator input is needed is performed only after all of the sensing vectors have been analyzed.

6. The method of claim 1, wherein:

the step of analyzing at least one of a plurality of the sensing vectors includes calculating a score related to the quality of detection available for a sensing vector; and

the step of determining that an identified sensing vector is suitable for cardiac event detection includes comparing the score for the selected sensing vector to a threshold.

7. The method of claim 1, wherein:

the step of analyzing at least one of a plurality of the sensing vectors includes calculating a score related to the quality of detection available for a sensing vector; and

the step of determining that an identified sensing vector is suitable for cardiac event detection includes selecting the sensing vector having the highest score.

8. The method of claim 1, wherein the step of analyzing at least one of a plurality of the sensing vectors includes attempting to calculate a score related to the quality of detection available for at least two of the sensing vectors, failing to calculate the score for at least one sensing vector due to uncertainty, establishing possible outcomes for the score given possible resolutions of the uncertainty, and setting a flag for the at least one sensing vector for which the score was not calculated.

9. The method of claim 8, wherein:

the step of determining that an identified sensing vector is suitable for cardiac event detection includes;

determining that a calculated score exceeds a predetermined threshold and selecting a corresponding sensing vector;

or

determining that a calculated score exceeds all other scores and possible outcomes and selecting a corresponding sensing vector; and

the step of determining that operator input is needed includes determining that a possible outcome exceeds all other possible outcomes and calculated scores.

10. A method of operating an implantable cardiac stimulus system comprising operational circuitry coupled to a plurality of sensing electrodes disposed within a patient and defining a plurality of sensing vectors for performing cardiac event detection, the method comprising:

analyzing a first sensing vector to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis, and if so, selecting the first vector for use in cardiac event detection and analysis;

otherwise, analyzing one or more additional sensing vectors.

11. The method of claim 10, wherein the step of analyzing one or more additional vectors includes:

analyzing a second sensing vector to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis, and if so, selecting the second cardiac vector for use in cardiac event detection and analysis;

otherwise, analyzing at least a third sensing vector.

12. The method of claim 11, wherein the step of analyzing at least a third sensing vector includes:

determining whether the third sensing vector is suitable, within given threshold conditions, for use in cardiac event detection and analysis and, if so, selecting the third cardiac vector for use in cardiac event detection and analysis;

otherwise, selecting a best vector from among the first, second, and third sensing vectors for use in cardiac event detection and analysis.

13. The method of claim 10, wherein the step of analyzing one or more additional vectors includes:

analyzing a second sensing vector to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis, and if so, selecting the second cardiac vector for use in cardiac event detection and analysis;

otherwise, selecting a best vector from among the first and second sensing vectors for use in cardiac event detection and analysis.

14. A method of operating an implantable cardiac stimulus system comprising a controller coupled to a plurality of sensing electrodes adapted for disposition in a patient, the method comprising:

executing instructions with the controller to analyze at least first and second sensing vectors defined between selected subsets of the plurality of sensing electrodes, the instructions adapted to generate either a score related to characteristics of a signal sensed along a selected sensing vector, or at least two possible scores and an indication of uncertainty relative to the possible scores; and

;

if no indications of uncertainty are generated, selecting whichever sensing vector has a highest score for use in detecting cardiac events;

or

if at least one indication of uncertainty is generated;

if a score exceeds other scores and all possible scores, selecting a corresponding sensing vector for use in detecting cardiac events without resolving uncertainty related to at least one possible score that does not exceed the identified score;

if an identified possible score exceeds all scores and other possible scores, requesting input from an operator to settle the uncertainty related to the possible score and, if the operator input resolves the uncertainty in favor of the identified possible score, selecting a corresponding sensing vector for use in detecting cardiac events.

15. The method of claim 14, wherein the step of requesting input from an operator includes asking the operator to determine whether the peak amplitude of a sensed QRS complex is greater than the peak amplitude of a sensed T-wave.

16. The method of claim 14, wherein the step of requesting input from an operator includes asking the operator to determine whether the peak amplitude of a sensed QRS complex is greater than the peak amplitude of a sensed noise signal.

17. The method of claim 14, wherein the step of requesting input from an operator includes asking the operator to determine whether a highest peak in a sensed signal is an R-wave peak.

18. A method of operating an implantable cardiac stimulus system comprising a controller coupled to a plurality of sensing electrodes adapted for disposition in a patient, the method comprising:

executing vectoring instructions with the controller to analyze a first sensing vector defined between a selected subset of the plurality of sensing electrodes, wherein the vectoring instructions are adapted to generate either a score related to characteristics of a signal sensed along a selected sensing vector, or at least two possible scores and an indication of uncertainty relative to the possible scores;

if the analysis of the first sensing vector generates a first score, comparing the first score to a first threshold and, if the first score exceeds the first threshold, selecting the first sensing vector for use in detecting cardiac events;

otherwise, executing the vectoring instructions with the controller to analyze a second sensing vector defined between another selected subset of the plurality of sensing electrodes; and

if the analysis of the second sensing vector generates a second score, comparing the second score to a second threshold and, if the second score exceeds the second threshold, selecting the second sensing vector for use in detecting cardiac events.

19. The method of claim 18, wherein the second sensing vector is not analyzed if the first score exceeds the first threshold.

20. The method of claim 18, further comprising:

if;

the first score does not exceed the first threshold or a first score is not generated, and

the second score does not exceed the second threshold or a second score is not generated;

then,

executing the vectoring instructions with the controller to analyze a third sensing vector defined between yet another selected subset of the plurality of sensing electrodes; and

if the analysis of the third sensing vector generates a third score, comparing the third score to a third threshold and, if the third score exceeds the third threshold, selecting the third sensing vector for use in detecting cardiac events.

21. The method of claim 20, wherein, if none of the first, second or third thresholds are exceeded, the method further comprises:

starting with a set of scores and/or possible scores generated by executing the vectoring instructions;

a) identifying a greatest available score from the scores and/or possible scores;

b) if the greatest available score is a score, selecting sensing vector corresponding to the score for use in detecting cardiac events;

c) if a greatest available score is a possible score, requesting input from an operator to determine whether the identified possible score should be treated as an actual score or discarded;

d) if the operator input indicates that the identified possible score should be treated as an actual score, selecting a sensing vector corresponding to the identified possible score for use in detecting cardiac events;

e) if the operator input indicates that the identified possible score should be discarded, removing the identified possible score from the set of scores and/or possible scores, treating an associated possible score as a score, and returning to step a).

22. The method of claim 18, wherein if first and second scores are generated by executing the vectoring instructions on the first and second sensing vectors and neither score exceeds a corresponding threshold, determining whether the greater of the first and second scores exceeds a third threshold and, if so, selecting the greater of the first and second scores for use in detecting cardiac events.

23. The method of claim 18, wherein the scores and possible scores are generated by calculating a signal-to-noise ratio and observing a peak amplitude for a selected sensing vector.

24. The method of claim 23, wherein the scores and possible scores are generated by inserting the signal-to-noise ratio and observed peak amplitude into a formula.

25. The method of claim 23, wherein the scores and possible scores are generated by inserting the signal-to-noise ratio and observed peak amplitude into a look-up table.

26. A method of cardiac signal analysis in an implantable cardiac stimulus system having a plurality of sensing electrodes and operational circuitry coupled thereto, the method comprising:

the operational circuitry executing vectoring instructions relative to a first sensing vector, the vectoring instructions causing the operational circuitry to return one of;

a) a score indicating the quality of a signal captured along the first sensing vector;

b) at least two possible scores indicating the quality of the signal captured along the first sensing vector wherein operator input is needed to determine which possible score is correct;

or

c) an indication that the sensing vector under review is unsuitable for cardiac signal sensing;

the operational circuitry determining whether the first sensing vector receives a score indicating that the first sensing vector is well suited to cardiac signal detection and, if not,

the operational circuitry executing the vectoring instructions relative to a second sensing vector.

27. The method of claim 26, further comprising:

the operational circuitry determining whether the second sensing vector receives a score indicating that the second sensing vector is well suited to cardiac signal detection and, if not,

the operational circuitry selecting which of the returned scores or possible scores is highest and, if a possible score is highest, the operational circuitry querying an operator for the device to determine whether the highest possible score is correct;

if so, a corresponding sensing vector is selected for use in detecting cardiac activity;

else,

the operational circuitry repeats the step of selecting which of the returned scores or possible scores is highest until a sensing vector is selected.

28. A method of cardiac signal analysis comprising analyzing data captured along one or more of a plurality of sensing vectors defined between implanted electrodes and selecting one of the plurality of sensing vectors for primary use in cardiac event detection, wherein the step of analyzing data captured along one of the plurality of sensing vectors includes:

identifying a number of detected events by comparison of a received signal to a detection threshold;

characterizing, by analysis of intervals between the detected events, most of the detected events as;

a) QRS events;

b) artifacts;

or

c) unidentifiable; and

if sufficient detected events are QRS events, calculating a signal-to-noise ratio and amplitude associated with the sensing vector;

otherwise

parsing, by analysis of event intervals and amplitudes, the unidentifiable events into;

a) QRS events;

b) artifacts;

or

c) unparseable; and

if sufficient detected events are now QRS events, calculating a signal-to-noise ratio and amplitude associated with the sensing vector.

29. The method of claim 28, wherein the steps are performed by operational circuitry of an implanted medical device.

30. The method of claim 28, wherein the step of identifying a number of detected events is performed by an implantable medical device, and the other steps are performed by a programmer adapted to communicate with the implantable medical device.

31. The method of claim 28, wherein at least one step is performed by an implantable medical device and at least one other step is performed by a programmer adapted to communicate with the implantable medical device.