Mitigating false messaging in leadless dual-chamber pacing systems and other IMD systems

• US 10,173,068 B2
• Filed: 02/02/2017
• Issued: 01/08/2019
• Est. Priority Date: 02/02/2017
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Chin, Donald
• Primary Examiner(s): Wong, Albert K
• Application Number:
  US15/423,409
• Publication Number:
  US 20180214704A1
• Time in Patent Office: 705 Days
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/362 Heart stimulators heart defibrillators A61N1/39
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators
• CPC Class Codes: G06F 11/1004 to protect a block of data words, e.g. CRC or checksum G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 1/201 Frame classification, e.g. bad, good or erased frame indication per se H04L1/0082

Abstract

Implantable medical devices (IMDs), and methods for use therewith, reduce how often an IMD accepts false messages. Such a method can include receiving a message and performing error detection and correction on the message. Such a method can also include determining a quality measure indicative of a quality of the message and/or a quality of a channel over which the message was received, and determining whether to reject the message based on the quality measure.

Claims

1. For use by an implantable medical device (IMD), a method for reducing how often the IMD accepts false messages, the method comprising:

receiving a message;

performing error detection and correction on the message;

determining a quality measure indicative of at least one of a quality of the message or a quality of a channel over which the message was received;

determining whether to reject the message based on the quality measure, wherein;

the IMD is a first leadless pacemaker (LP) configured to be implanted in a first chamber of a patient'"'"'s heart and configured to selectively deliver pacing pules;

the message is received by the first LP from a second LP that is configured to be implanted in second chamber of a patient'"'"'s heart and configured to at least one of sense intrinsic depolarizations or selectively deliver pacing pulses;

the message is indicative of when the second LP sensed an intrinsic depolarization or delivered a pacing pulse; and

the message, if accepted, is used to trigger a timer of the first LP.

6. The method of claim 1, wherein the quality measure is based on whether an amplitude or power of a received signal including the message is within an expected amplitude or power range.

7. The method of claim 1, wherein the quality measure is based on whether a timing of the message is within an expected timing range.

8. The method of claim 1, wherein the determining whether to reject the message comprises:

determining that the message should be rejected if the quality measure is below a corresponding lower threshold;

determining that the message should not be rejected if the quality measure is above a corresponding upper threshold; and

if the quality measure is between the corresponding lower and upper thresholds, then determining that the message should be rejected if the preceding message was rejected, and determining that the message should not be rejected if the preceding message was not rejected.

9. The method of claim 1, wherein the quality measure is indicative of the quality of the channel over which the message was received.

10. The method of claim 9, further comprising:

measuring noise associated with the channel over which the message was received; and

determining the quality of the channel over which the message was received based on the measured noise associated with the channel.

11. The method of claim 9, wherein the determining whether to reject the message comprises:

determining that the message should be rejected if the quality measure is below a corresponding lower threshold;

determining that the message should not be rejected if the quality measure is above a corresponding upper threshold; and

if the quality measure is between the corresponding lower and upper thresholds, then determining that the message should be rejected if the preceding message was rejected, and determining that the message should not be rejected if the preceding message was not rejected.

2. The method of claimed 1, wherein the quality measure is indicative of a quality of the message.

3. The method of claim 2, wherein;

the determining the quality measure indicative of the quality of the message is based on results of the error detection and correction;

the results of the error detection and correction specify one of at least two different levels of message quality; and

the method further comprises;

mapping the results of the error detection and correction to one of at least two different numbers;

adjusting an average message quality based on the number; and

comparing the average message quality to one or more thresholds; and

the determining whether to reject the message based on the quality measure comprises determining whether to reject the message based on results of the comparing the average message quality to the one or more thresholds.

4. The method of claim 3, wherein the mapping the results of the error detection and correction to one number of at least two different numbers includes:

mapping the results of the error detection and correction to a first number if the results indicated the message was cleanly received without any correcting being needed;

mapping the results of the error detection and correction to a second number that is less than the first number if the results indicated the message was corrected; and

mapping the results of the error detection and correction to a third number that is less than the second number if the results indicated the message was uncorrectable.

5. The method of claim 4, wherein the adjusting the average message quality based on the number is performed using an equation Q =(1−

1/b)*Q+N*(1/b), where Q is the average message quality, N is the number to which the results of the error detection and correction was mapped, and b a time constant parameter that controls a rate of change.

12. An implantable medical device (IMD), comprising:

at least one receiver configured to receive messages; and

at least one of a processor or controller configure to;

perform error detection and correction on a message received by the at least one receiver;

determine a quality measure indicative of at least one of a quality of the message or a quality of a channel over which the message was received; and

determine whether to reject the message based on the quality measure, wherein;

the IMD is a first leadless pacemaker (LP) configured to be implanted in a first chamber of a patient'"'"'s heart and configured to selectively deliver pacing pules;

the at least one receiver receives messages from a second LP that is configured to be implanted in a second chamber of a patient'"'"'s heart and configured to at least one of sense intrinsic depolarizations or selectively deliver pacing pulses;

at least some of the messages received by the at least one receiver are indicative of when the second LP sensed an intrinsic depolarization or delivered a pacing pulse; and

at least some of the message, if accepted, are used to trigger a timer of the first LP.

13. The IMD of claim 12, wherein the quality measure is indicative of a quality of the message.

14. The IMD of claim 12, wherein the quality measure is indicative of the quality of the channel over which the message was received.

15. For use by an implantable medical device (IMD), a method for reducing how often the IMD accepts false messages, the method comprising:

receiving a message;

performing error detection and correction on the message;

determining a first quality measure indicative of a quality of the message;

determining a second quality measure indicative of a quality of a channel over which the message was received; and

determining whether to reject the message based on the first and second quality measures, wherein;

the IMD is a first leadless pacemaker (LP) configured to be implanted in a first chamber of a patient'"'"'s heart and configured to selectively deliver pacing pules;

the at least one receiver receives messages from a second LP that is configured to be implanted in a second chamber of a patient'"'"'s heart and configured to at least one of sense intrinsic depolarizations or selectively deliver pacing pulses;

at least some of the messages received by the at least one receiver are indicative of when the second LP sensed an intrinsic depolarization or delivered a pacing pulse; and

at least some of the message, if accepted, are used to trigger a timer of the first LP.

16. The method of claim 15, wherein the determining the first quality measure is based on results of the error detection and correction.

17. The method of claim 15, further comprising;

measuring noise associated with the channel over which the message was received; and

determining the second quality measured based on the measured noise associated with the channel.

18. The method of claim 15, wherein determining whether to reject the message based on the first and second quality measures comprises:

comparing each of the first and second quality measures to one or more respective thresholds; and

determining whether to reject the message based on results of the comparing.

19. The method of claim 15, further comprising;

producing a combined quality measure based on the first and second quality measures; and

wherein determining whether to reject the message based on the first and second quality measures comprises

comparing the combined quality measure to one or more thresholds; and

determining whether to reject the message based on results of the comparing.