DDI pacing with PVC-protected hysteresis and automatic AV interval adjustment

• US 5,417,714 A
• Filed: 05/11/1993
• Issued: 05/23/1995
• Est. Priority Date: 03/05/1992
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Clarke, Malcolm, Poore, John W., Levine, Paul A., Sholder, Jason A.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Parker, Marianne
• Application Number:
  US08/060,765
• Time in Patent Office: 742 Days
• Field of Search: 607/9, 607/15, 607/18, 607/25
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay

Abstract

A dual-chamber pacemaker provides DDI pacing with PVC-protected hysteresis and automatic AV interval adjustment. An extended hysteresis atrial escape interval (AEI_H) is invoked in response to the occurrence of either an atrial paced event followed by a sensed R-wave (an AR event), or an atrial sensed event followed by a sensed R-wave (a PR event). The occurrence of a premature ventricular contraction (PVC) thus does not trigger AEI_H. In one embodiment, AEI_H is not invoked unless the sensed AR or PR interval exceeds a prescribed reference interval. In a further embodiment, the AV interval (AVI) associated with the DDI operation is automatically shortened following an atrial stimulation pulse (A-pulse) delivered upon the timing-out of the AEI_H. The shortened AVI is maintained for a programmed number of cycles of DDI operation, after which a lengthened AVI is reestablished for one cycle. If AV pacing follows after using the lengthened AVI, then the shortened AVI is reinstated for a second number of programmed cycles of DDI operation. If AR pacing follows after using the lengthened AVI, signifying intact AV nodal conduction, then the AVI is lengthened to the programmed AVI over a prescribed number of cycles.

Claims

1. A dual-chamber implantable pacemaker having a hysteresis DDI mode of operation comprising:

an atrial channel comprising an atrial pulse generator and an atrial sense amplifier;

a ventricular channel comprising a ventricular pulse generator and a ventricular sense amplifier;

timing means for defining an atrial escape interval (AEI) and an AV interval, said AEI assuming one of at least two programmable values, a first value AEI₁ comprising a normal atrial escape interval, and a second value AEI_H comprising a hysteresis atrial escape interval;

a control circuit for controlling the atrial channel and the ventricular channel, said control circuit comprising;

(1) means for initiating an atrial pulse (A-pulse) to be generated by said atrial pulse generator when the AEI terminates, unless an atrial event (P-wave) is sensed by the atrial sense amplifier during the AEI, in which case the A-pulse is inhibited from being generated;

(2) means for initiating a ventricular pulse (V-pulse) to be generated by said ventricular pulse generator when the AV interval terminates, unless a ventricular event (R-wave) is sensed by the ventricular sense amplifier during the AV interval, in which case the V-pulse is inhibited from being generated;

(3) means for initiating the AEI to begin upon the occurrence of an R-wave or a V-pulse, said AEI assuming said hysteresis AEI_H value only upon the occurrence of;

(a) an R-wave following a P-wave (a PR event), or (b) an R-wave following an A-pulse (an AR event), and assuming said normal AEI₁ value at all other times; and

(4) means for initiating the AV interval to begin following the AEI;

wherein the consecutive occurrence of said AEI and said AV interval comprises a cardiac cycle.

2. The pacemaker, as set forth in claim 1, wherein the control circuit further includes means for measuring a time interval between a P-wave and a succeeding R-wave of a PR event (a PR event interval), and between an A-pulse and a succeeding R-wave of an AR event (an AR event interval), and wherein the control circuit causes the AEI to assume said second value AEI_H only when the determined PR or AR event interval exceeds a prescribed reference interval.

3. The pacemaker, as set forth in claim 1, wherein said AV interval is a first value, AVI₁, and further wherein said control circuit causes said AV interval to assume a second value, AVI₂, shorter than said first value AVI₁, for a prescribed number n of cardiac cycles, whenever an A-pulse is generated by said atrial pulse generator following an AEI of said second value, AEI_H.

4. The pacemaker, as set forth in claim 3, wherein said control circuit, after said prescribed number n of cardiac cycles using said AV interval of said second value, AVI₂, causes said AV interval to temporarily assume said first value, AVI₁, for at least one test cardiac cycle, and wherein after said at least one test cardiac cycle said control circuit further causes:

said AV interval to assume said second value, AVI₂, for a prescribed number m of cardiac cycles provided a V-pulse is generated by said ventricular pulse generator when the AV interval of said at least one test cardiac cycle terminates, and

said AV interval to permanently return to said first value, AVI₁, provided an R-wave is sensed by said ventricular sensing means prior to the AV interval of said at least one test cardiac cycle terminating.

5. The pacemaker, as set forth in claim 4, wherein said control circuit causes said AV interval to return to said first value AVI₁ in a single cardiac cycle, whereby an abrupt transition from said second value AVI₂ to said first value AVI₁ is provided for said AV interval.

6. The pacemaker, as set forth in claim 4, wherein said control circuit causes said AV interval to return to said first value AVI₁ in incremental steps over a plurality of cardiac cycles, whereby a smooth transition from said second value AVI₂ to said first value AVI₁ is provided for said escape interval.

7. A dual-chamber implantable pacemaker comprising:

an atrial channel that includes means for sensing P-waves and means for generating A-pulses;

a ventricular channel that includes means for sensing R-waves and means for generating V-pulses;

a control system that controls the operation of said atrial channel and ventricular channel so as to operate said implantable pacemaker in a DDI hysteresis mode, said control system including;

timing means for defining an atrial escape interval (AEI) and an AV interval, the sequential occurrence of said AEI and said AV interval comprising a cardiac cycle, with the AV interval beginning at the conclusion of the AEI, and with the AEI beginning at the conclusion of the AV interval or upon the occurrence of an R-wave, whichever event occurs first in a given cardiac cycle;

control means for;

(1) causing an A-pulse to be generated in said atrial channel only upon the timing-out of said AEI without having sensed a P-wave during said AEI;

(2) inhibiting the generation of an A-pulse in said atrial channel only upon sensing a P-wave in said atrial channel prior to the timing-out of said AEI;

(3) causing a V-pulse to be generated in said ventricular channel only upon the timing-out of said AV interval without having sensed an R-wave during said AV interval;

(4) inhibiting the generation of a V-pulse in said ventricular channel only upon sensing an R-wave in said ventricular channel prior to the timing-out of said AV interval; and

(5) immediately terminating said AV interval upon the sensing of an R-wave in said ventricular channel prior to the timing-out of said AV interval;

said AEI being defined by said timing means to assume a first interval value AEI₁ following the generation of a V-pulse in said ventricular channel,, and a second interval value AEI_H comprising a hysteresis AEI value following a PR event or an AR event, a PR event comprising an K-wave following a P-wave, and an AR event comprising an R-wave following an A-pulse, said AV interval value being defined by said timing means to assume a first AV interval value AVI- following the termination of said AEI, regardless of whether said AEI has assumed said first interval value AEI₁ or said second interval value AEI_H ;

a memory circuit coupled to said control system for storing control signals associated with the operation of said control system, said control signals including at least one AEI value signal and at least one AVI value signal, said AEI₁, AEI_H, and AVI₁ values being defined by said timing means as a function of said at least one AEI and AVI value signals; and

telemetry means for allowing said control signals to be programmed into said memory circuit from a location external to said implantable pacemaker.

8. The dual-chamber implantable pacemaker, as defined in claim 7, wherein said timing means of said control system is further for determining a time interval between an atrial event and a succeeding R-wave (an atrial/R interval), and wherein the AEI is defined by said timing means to assume said AEI_H value only when the determined atrial/R interval exceeds a prescribed reference interval.

9. The dual-chamber implantable pacemaker, as defined in claim 8, wherein said prescribed reference interval comprises one of said control signals programmed into said memory circuit via said telemetry means.

10. The dual-chamber implantable pacemaker, as defined in claim 8, wherein said prescribed reference interval comprises a time interval commonly within a range of 80 to 130 milliseconds, but programmable by the physician.

11. The dual-chamber implantable pacemaker, as defined in claim 7, wherein AEI_H is longer than AEI₁, and wherein the timing means of said control system defines said AV interval to assume a shortened AV interval value, AVI₂, where AVI₂ is less than AVI₁, for a prescribed number n of cardiac cycles, whenever an A-pulse is generated within said atrial channel following an AEI of said second interval value, AEI_H.

12. The dual-chamber implantable pacemaker, as defined in claim 11, wherein said control system, after said prescribed number n of cardiac cycles with said AV interval assuming said shortened AV interval value, AVI₂, causes said AV interval to temporarily assume a lengthened AV interval value for at least one test cardiac cycle, and wherein after said at least one test cardiac cycle the timing means of said control system further defines:

said AV interval to assume said shortened AV interval value AVI₂ for a prescribed number m of cardiac cycles provided a V-pulse is generated in said ventricular channel when the temporarily lengthened AV interval of said at least one test cardiac cycle terminates, and

said AV interval to assume said first AV interval value AVI₁ that provided an AR event or a PR event concludes during said temporarily lengthened escape interval of said at least one test cardiac cycle.

13. The dual-chamber implantable pacemaker, as defined in claim 12, wherein the prescribed number n of cardiac cycles is equal to the prescribed number m of cardiac cycles.

14. The dual-chamber implantable pacemaker, as defined in claim 12, wherein the timing means of said control system causes said AV interval to return to said first AV interval value AVI₁ in a single cardiac cycle, whereby said AV interval abruptly changes from said AVI₂ interval value to said AVI₁ interval value.

15. The dual-chamber implantable pacemaker, as defined in claim 12, wherein the timing means of said control system causes said AV interval to return to said first AV interval value AVI₁ in incremental steps over a plurality of cardiac cycles, whereby said AV interval smoothly changes from said AVI₂ interval value to said AVI₁ interval value.

16. A method of operating a dual-chamber implantable pacemaker so that it operates in a DDI hysteresis mode, said dual-chamber implantable pacemaker including:

(1) an atrial channel that includes atrial sensing means for sensing a P-wave and atrial pacing means for generating an A-pulse, (2) a ventricular channel that includes ventricular sensing means for sensing an R-wave and ventricular pacing means for generating a V-pulse, and (3) a control system that monitors the atrial and ventricular sensing means and controls the atrial and ventricular pacing means in accordance with the DDI hysteresis mode of operation, said method comprising the steps of;

(a) defining two possible values for an atrial escape interval, AEI, to used by said control system, a first value AEI₁ comprising a normal AEI, and a second value AEI_H comprising a hysteresis AEI, with AEI_H being longer than AEI₁ ;

(b) defining an AV interval, AVI, to be used by said control system;

(c) initially setting AEI to one of said AEI₁ or AEI_H ;

(d) starting the AEI;

(e) sensing whether a P-wave occurs before the AEI times out; and

, if so, inhibiting the generation of an A-pulse upon the timing-out of the AEI; and

, if not so, generating an A-pulse upon the timing-out of the AEI;

(f) starting the AVI upon the AEI timing-out;

(g) sensing whether an R-wave occurs in the ventricular channel prior to the AVI timing out, and

(1) if so, terminating the AVI immediately upon the sensing of the R-wave, inhibiting the generation of a V-pulse, and determining whether the sensed R-wave represents the culmination of a PR event or an AR event, a PR event comprising a P-wave sensed in the atrial channel followed by an R-wave sensed in the ventricular channel, and an AR event comprising an A-pulse generated in the atrial channel followed by an R-wave sensed in the ventricular channel, and

(2) if not so, generating a V-pulse immediately upon the AVI timing out;

(h) setting the AEI to AEI_H only if an R-wave is sensed in step (g) and if said sensed R-wave represents the culmination of a PR event or an AR event;

(i) setting the AEI to AEI₁ if a V-pulse is generated in step (g);

(j) starting the AEI immediately upon the termination of the AVI, if an R-wave is sensed in step (g), or immediately upon the AVI timing-out if an R-wave is not sensed in step (g); and

(h) repeating steps (e)-(j) for so long as the DDI hysteresis mode of operation is to continue.

17. The method, as set forth in claim 16, further including as part of step (g) determining a time interval between the A-pulse and the R-wave of an AR event, or a time interval between the P-wave and the R-wave of a PR event, whichever AR or PR event occurs, and wherein step (h) comprises setting the AEI to AEI_H only if an R-wave is sensed in step (g) and if the determined time interval between the A-pulse and the R-wave of the AR event, or between the P-wave and the R-wave of the PR event, is greater than a prescribed reference time interval.

18. The method, as set forth in claim 16, wherein step (b) comprises defining two possible values for said AV interval, AVI₁ and AVI₂, with AVI₁ being greater than AVI₂, and initially using AVI₁ as the value of the AVI, but switching to using AVI₂ as the value of the AVI upon the generating of an A-pulse when the AEI concludes provided the AEI has assumed said AEI_H value, and continuing to use AVI₂ as the value of the AVI during the DDI hysteresis mode of operation for at least a prescribed number n of cardiac cycles, a cardiac cycle comprising a consecutive occurrence of the AEI and the AVI.

19. The method, as set forth in claim 18, wherein, after said prescribed number n of cardiac cycles, said method further includes:

momentarily lengthening the AVI;

returning the value of the AVI back to AVI₂ provided the momentarily lengthened AVI times-out without an R-wave having been sensed, and

reinstating the value of the AVI to AVI₁ in the event that an R-wave is sensed prior to the timing-out of the momentarily lengthened AVI.

20. The method, as set forth in claim 19, wherein the step of momentarily lengthening of the AVI comprises setting AVI to AVI₁ for one cardiac cycle.

21. The method, as set forth in claim 19, wherein the step of reinstating the value of the AVI to AVI₁ comprises abruptly setting AVI to AVI₁.

22. The method, as set forth in claim 19, wherein the step of reinstating the value of the AVI to AVI₁ comprises gradually returning the value of AVI to AVI₁ from AVI₂.

23. The method, as set forth in claim 19, wherein the step of returning the value of the AVI back to AVI₂ in the event that the momentarily lengthened AVI times-out without an R-wave having been sensed comprises returning the value of the AVI back to AVI₂ over a prescribed number m of cardiac cycles.

24. The method, as set forth in claim 23, wherein the prescribed number n of cardiac cycles equals the prescribed number m of cardiac cycles.