Pacemaker passive measurement testing system and method

• US 6,370,432 B1
• Filed: 08/20/1999
• Issued: 04/09/2002
• Est. Priority Date: 08/20/1999
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Gilkerson, James O., Perschbacher, David L., Conley, Vickie L.
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US09/378,315
• Time in Patent Office: 963 Days
• Field of Search: 607/4, 607/27, 607/28, 607/59
• US Class Current: 607/27
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371

Abstract

A system and method for passively testing a cardiac pacemaker in which sensing signal amplitudes and lead impedance values are measured and stored while the pacemaker is functioning in its programmed mode. The amplitude and impedance data may be gotten and stored periodically at regular intervals to generate a historical record for diagnostic purposes. Sensing signal amplitudes may also be measured and stored from a sensing channel which is currently not programmed to be active as long as the pacemaker is physically configured to support the sensing channel. Such data can be useful in evaluating whether a switch in the pacemaker'"'"'s operating mode is desirable.

Claims

1. A method for testing a dual-chamber cardiac pacemaker irrespective of the pacemaker'"'"'s operation according to a particular programmed mode, where a programmed mode includes a plurality of operating states, comprising:

detecting when the pacemaker enters a programmed sensing state corresponding to receipt of a sense signal from a heart chamber sensing channel;

entering an amplitude storing state which stores an amplitude value corresponding to the sense signal in a memory; and

,

transitioning to a virtual sensing test state upon receipt of a sensing signal in a currently unprogrammed sensing channel and storing an amplitude value corresponding to the sense signal in memory, wherein the virtual sensing test state corresponds to a currently unprogrammed sensing channel with the pacemaker operating as if programmed in a mode including that virtual sensing test state but with no triggering or inhibition of pacing by the virtual sensing test state.

2. The method of claim 1 further comprising:

detecting when the pacemaker enters a pacing state corresponding to occurrence of an event which triggers output of a pacing pulse through a lead to a heart chamber according to the programmed mode; and

,

entering a lead impedance measuring state which measures an impedance value of the lead through which the pacing pulse is delivered during output of the pacing pulse and stores the value in a memory.

3. The method of claim 1 wherein the method is performed as part of a passive measurement testing mode which when activated causes the method to be performed until either amplitude values corresponding to each sensing channel of the pacemaker are stored or a selected amplitude test time interval expires.

4. The method of claim 3 wherein the method is performed as part of a passive measurement testing mode which when activated causes the method to be performed until either lead impedance values corresponding to each lead of the pacemaker are stored or a selected lead test time interval expires.

5. The method of claim 4 further comprising:

upon expiration of the selected lead test time interval, transitioning to a virtual pacing test state after receipt of a sensing signal from a heart chamber and during which a pacing pulse is output to the heart chamber during the chamber'"'"'s refractory period; and

,

measuring an impedance value of the lead through which the pacing pulse is delivered during output of the pacing pulse and storing the value in a memory.

6. The method of claim 5 wherein the passive measurement testing mode is activated periodically at selected times.

7. The method of claim 6 wherein the amplitude and lead impedance values corresponding to each activation of the passive measurement testing mode are stored in a data structure.

8. The method of claim 7 wherein the data structure maintains a record of amplitude and lead impedance values corresponding to a selected number of most recent activations of the passive measurement testing mode.

9. The method of claim 8 further comprising calculating and storing an average amplitude value for each sensing channel and an average lead impedance value for each lead, the averages being taken over the amplitude and lead impedance values currently stored in the data structure.

10. The method of claim 9 wherein the average amplitude and lead impedance values are calculated and stored after each activation of the passive measurement testing mode.

11. A processor-readable storage medium having processor-executable instructions for performing the method recited in claim 1.

12. A cardiac pacemaker, comprising:

a plurality of sensing channels, each such channel including an electrode for disposing near a chamber of the heart and a sense amplifier for detecting sense signals;

one or more pacing channels that include a pulse generator for outputting pacing pulses to an electrode disposed near a ventricle;

a controller for controlling the operation of the pulse generators in response to sensed events and lapsed time intervals and in accordance with a programmed pacing mode;

wherein the controller is programmed to;

enter an amplitude storing test state following receipt of a sensing signal from a programmed sensing channel during which an amplitude value corresponding to the sensing signal is stored; and

,

enter a virtual sensing test state following receipt of a sensing signal from a currently unprogrammed sensing channel, during which an amplitude value corresponding to the sensing signal is stored but no triggering or inhibition of pacing pulses is effected.

13. The pacemaker of claim 12 wherein the controller is further programmed to enter a lead impedance measuring state upon the pacemaker entering a pacing state corresponding to occurrence of an event which triggers output of a pacing pulse through a lead to a heart chamber according to a currently programmed mode, during which an impedance of the lead through which the pacing pulse is delivered is measured during output of the pacing pulse and stored.

14. The pacemaker of claim 13 wherein the controller is further programmed to:

enter a passive measurement testing mode which when entered causes the pacemaker to transition to the amplitude storing, virtual sensing, and lead impedance measuring states when appropriate input conditions are met;

terminate the passive measurement testing mode when an amplitude value for each sensing channel and a lead impedance value have been stored or upon expiration of a selected test interval.

15. The pacemaker of claim 13 wherein the controller is further programmed to enter a virtual pacing test state after receipt of a sensing signal from a heart chamber and during which a pacing pulse is output to the heart chamber during the chamber'"'"'s refractory period.

16. The pacemaker of claim 14 wherein the controller is programmed to activate the passive measurement testing mode periodically at selected times.

17. The pacemaker of claim 16 wherein the controller is programmed to store the amplitude and lead impedance values corresponding to each activation of the passive measurement testing mode.

18. The pacemaker of claim 17 wherein the wherein the controller is programmed to maintain a record of amplitude and lead impedance values corresponding to a selected number of most recent activations of the passive measurement testing mode.

19. The pacemaker of claim 18 wherein the controller is programmed to calculate and store an average amplitude value for each sensing channel and an average lead impedance value for each lead, the averages being taken over the amplitude and lead impedance values currently stored in the data structure.

20. The pacemaker of claim 19 wherein the average amplitude and lead impedance values are calculated and stored after each activation of the passive measurement testing mode.

21. The pacemaker of claim 12 wherein the controller is further programmed to:

enter a passive measurement testing mode which when entered causes the pacemaker to transition to the amplitude storing test state when appropriate input conditions are met; and

,

terminate the passive measurement testing mode when an amplitude value for each sensing channel has been stored or upon expiration of a selected amplitude test interval.

22. A cardiac pacemaker having at least two sensing channels for sensing separate chambers of the heart and being capable of operating in a programmed mode such that one or more of the sensing channels are inactive, the pacemaker further comprising means for testing an inactive channel while the pacemaker is operating in the programmed mode.

23. The cardiac pacemaker of claim 22 wherein the testing means measures and stores a signal amplitude.

24. The cardiac pacemaker of claim 23 wherein the testing means comprises means for testing an atrial channel while the pacemaker is operating in a mode where the atrial channel is inactive.