Automatic LV / RV capture verification and diagnostics

• US 20060136002A1
• Filed: 12/20/2005
• Published: 06/22/2006
• Est. Priority Date: 12/20/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Kleckner, Karen J., Sheth, Nirav V., Burnes, John E.
• Granted Patent: US 7,555,336 B2
• Time in Patent Office: Days
• US Class Current: 607/27
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

The present invention provides a technique for verifying pacing capture of a ventricular chamber, particularly to ensure desired delivery of a ventricular pacing regime (e.g., cardiac resynchronization therapy or “CRT”). The invention also provides for ventricular capture management by delivering a single ventricular pacing stimulus and checking inter-ventricular conduction during a temporal window to determine if the ventricular pacing stimulus captured the chamber. If a loss-of-capture (LOC) signal results from the capture management testing, then the characteristics of the applied pacing pulses are modified and the conduction test repeated. In the event that the LOC signal persists, a pacing mode-switch to an atrial-based pacing therapy and/or non-bi-ventricular pacing regimen can be implemented.

Claims

1. A method of monitoring ventricular capture in a ventricular cardiac resynchronization therapy (CRT) delivery device to promote mechanical synchrony between ventricular chambers, comprising:

suspending a CRT delivery regimen;

verifying an absence of possibly deleterious cardiac rhythms, and after successfully verifying the absence of possibly deleterious cardiac rhythms;

conducting a ventricular conduction test to a first ventricle, wherein the first ventricle receives pacing stimulation;

monitoring a second ventricle during a period of time following , wherein said second ventricle is free of direct pacing stimulation, for inter-ventricular conduction of said pacing stimulation from said first ventricle.

2. A method according to claim 1 wherein said ventricular conduction test comprises:

extending a cardiac pacing atrio-ventricular (AV) interval;

measuring a PR time interval, said interval defined as the time elapsed between a sensed or paced atrial event (A-event) and an antegrade-conducted right ventricular sense (RVs) event, or, in the event that a ventricular pace occurs upon the expiration of the extended AV interval, assuming the presence of some degree of AV block and between said A-event and the ventricular pace, and

programming one of a relatively short AV interval and a minimum AV interval as the test AV interval.

3. A method according to claim 2, further comprising:

delivering a left ventricle-only pacing stimulus (LVp) and in the event that no right ventricular sense (RVs) event occurs prior to delivery of a next-scheduled right ventricular pace (RVp) declaring loss of capture (LOC) of said LV chamber.

4. A method according to claim 3, comprising repeating the step recited in claim 3 and in the event that LOC is again declared,

confirming the initial declaration of LV LOC.

5. A method according to claim 4, further comprising:

issuing an output signal reflecting the LV LOC declaration.

6. A method according to claim 5, wherein said output signal is stored within a memory structure.

7. A method according to claim 5, wherein said output signal is provided wirelessly to one of a cardiac device programming apparatus and a remote work station.

8. A method according to claim 7, wherein said remote work station comprises one of a patient monitor, a clinician transceiver, a processor-controlled device coupled to a patient information network.

9. A method according to claim 8, wherein said patient monitor comprises means for alerting said patient to the results of at least one of the parameters of said ventricular capture monitoring method.

10. A method according to claim 9, wherein the at least one of the parameters comprises:

a test AV interval, a PR interval, a set of temporal pacing parameters, a pacing stimulation metric;

a heart rate, an activity rate, a metabolic state, a presence of an ischemia episode, a presence of pulmonary edema.

11. A method according to claim 10, wherein the pacing stimulation metrics comprises at least one of:

an SAV interval, a PAV interval, a pulse width, a pulse amplitude, a polarity characteristic.

12. A method according to claim 1, wherein said possibly deleterious cardiac rhythms comprise at least one of the group:

a premature ventricular contraction (PVC),

a premature atrial contraction (PAC),

an episode of supra-ventricular tachycardia (SVT),

an episode of ventricular tachycardia (VT),

an episode of ventricular fibrillation (VF),

an episode of pulsus alternans,

an episode of acute ischemia,

an episode of pulmonary edema,

a detected intrinsic heart rate exceeding a predetermined threshold,

a paced heart rate exceeding a predetermined threshold,

an activity sensor output exceeding a predetermined threshold,

an estimated pulmonary arterial diastolic (ePAD) pressure exceeding a predetermined upper threshold,

an estimated pulmonary arterial diastolic (ePAD) pressure exceeding a predetermined lower threshold,

an episode of heart failure decompensation,

an episode of hypertension,

a patient-activated testing abort signal.

13. A method according to claim 12, further comprising:

distinguishing between an intrinsically-conducted (PR) event, a conducted intra-ventricular event, a conducted inter-ventricular event, and a PVC.

14. A method according to claim 2, further comprising:

delivering a left ventricle-only pacing stimulus (LVp); and

in the event that an RVs event occurs more than 40 ms prior to the measured PR interval declaring capture of said LV,

in the event that an RVs event occurs subsequent to a predetermined late-RV-sense interval declaring loss of capture of said LV,

in the event that an RVs event occurs with a duration approximately equal to the measured PR interval declaring capture as one of unknown or suspect.

15. A method according to claim 14, further comprising:

determining whether the RVs event occurred relatively early by applying pre-selected criteria; and

declaring positive detection of one of a conducted intra-ventricular event and a premature ventricular contraction (PVC).

16. A method according to claim 15, wherein the preselected criteria comprises:

setting the test AV interval to the measured PR interval minus approximately 40 ms;

repeating the steps of the method and if the Vs event occurs, confirming pacing capture of the LV.

17. A method according to claim 14, comprising repeating the step recited in claim 14 and in the event that capture is again declared,

confirming the initial declaration of LV capture.

18. A method according to claim 14, and in the event that LOC is declared, further comprising:

repeating said ventricular capture testing method by delivering an increased pacing pulse energy and/or in an alternative polarity.

19. A method according to claim 14, and in the event that LOC is declared, further comprising:

switching to and delivering one of;

an atrial-biased, minimal ventricular pacing therapy and a uni-ventricular, fusion-based pacing therapy.

20. An apparatus for monitoring ventricular capture in a ventricular cardiac resynchronization therapy (CRT) delivery device to promote mechanical synchrony between ventricular chambers, comprising:

means for suspending a CRT delivery regimen;

means for verifying an absence of possibly deleterious cardiac rhythms;

means for conducting a ventricular conduction test wherein a first ventricle receives pacing stimulation and a second ventricle is monitored for inter-ventricular conduction of said pacing stimulation to said first ventricle after successfully verifying the absence of possibly deleterious cardiac rhythms; and

means for monitoring a second ventricle during a subsequent period of time, wherein said second ventricle is free of direct pacing stimulation, for inter-ventricular conduction of said pacing stimulation from said first ventricle.

21. An apparatus according to claim 20, wherein said ventricular conduction test further comprises:

means for extending a cardiac pacing atrio-ventricular (AV) interval;

means for measuring a PR time interval, said interval defined as the time elapsed between a sensed or paced atrial event (A-event) and an antegrade-conducted right ventricular sense (RVs) event, or, in the event that a ventricular pace occurs upon the expiration of the extended AV interval between said A-event and the ventricular pace; and

means for programming one of a relatively short AV interval and a minimum AV interval as the test AV interval.

22. An apparatus according to claim 21, further comprising:

means for delivering a left ventricle-only pacing stimulus (LVp) and in the event that no right ventricular sense (RVs) event occurs prior to delivery of a next-scheduled right ventricular pace (RVp) declaring loss of capture (LOC) of said LV chamber.

23. An apparatus according to claim 21, further comprising:

delivering a left ventricle-only pacing stimulus (LVp) and in the event that an RVs event occurs more than 40 ms prior to the measured PR interval declaring capture of said LV.

24. An apparatus according to claim 23, further comprising:

means for confirming the initial declaration of LV LOC in the event that LOC is again declared and means for performing a mode-switch to an atrial tracking mode of delivering pacing therapy.

25. An apparatus according to claim 24, further comprising:

means for issuing an output signal reflecting the LV LOC declaration.

26. An apparatus according to claim 25, wherein said output signal is stored within a memory structure.

27. An apparatus according to claim 25, wherein said output signal is provided wirelessly to one of a cardiac device programming apparatus and a remote work station.

28. An apparatus according to claim 27, wherein said remote work station comprises one of a patient monitor, a clinician transceiver, a processor-controlled device coupled to a patient information network.

29. An apparatus according to claim 28, wherein said patient monitor comprises means for alerting said patient to the results of at least one of the parameters of said ventricular capture verification method.

30. An apparatus according to claim 29, wherein the at least one of the parameters comprises:

a test AV interval, a PR interval, a set of temporal pacing parameters, a pacing stimulation metric;

a heart rate, an activity rate, a metabolic state, a presence of an ischemia episode, a presence of pulmonary edema.