Pacemaker with vasovagal syncope detection

• US 5,676,686 A
• Filed: 04/25/1996
• Issued: 10/14/1997
• Est. Priority Date: 05/20/1994
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Jensen, Donald Nick, Hess, Michael F.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/637,579
• Time in Patent Office: 537 Days
• Field of Search: 607/9, 607/23
• US Class Current: 607/9
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585

Abstract

A method and apparatus for cardiac pacing, which provides for delivery of pacing pulses at an increased rate in response to a detected rapid drop in heart rate. A rapid drop may be detected in response to a drop of greater than a defined amount from the highest detected heart rate, over a preceding time period. Alternatively, an unbroken sequence of pacing pulses delivered at a base pacing rate may trigger pacing at an increased pacing rate.

Claims

1. A cardiac pacer comprising:

means for detecting depolarizations of a heart;

means for determining spontaneous heart depolarization rate;

pulse generating means for delivering cardiac pacing pulses at a first pacing rate;

drop detecting means for detecting a rapid drop in spontaneous heart depolarization rate, said drop detecting means comprising means for identifying a highest persistent heart rate over a limited time interval and means for determining whether said spontaneous heart depolarization rate has dropped more than a defined amount from said highest persistent heart rate; and

means responsive to a said detected rapid drop in spontaneous heart depolarization rate for causing said pulse generator means to deliver pacing pulses at a second pacing rate higher than said first pacing rate.

2. A cardiac pacer according to claim 1 wherein said means for detecting said highest persistent heart rate comprises means for identifying a fastest sequence of a predetermined number of beats, during said limited time interval.

3. A cardiac pacer according to claim 2 wherein said means for detecting said highest persistent heart rate comprises means for identifying a fastest sequence of two beats, during said limited time interval.

4. A cardiac pacer according to claim 3 wherein said means for detecting said highest persistent heart rate comprises means for identifying a rate of the slowest of said beats in said fastest sequence of two beats, as said highest persistent heart rate.

5. A cardiac pacer according to claim 2 or claim 3 or claim 4 wherein said means for detecting said highest persistent heart rate comprises means for defining a series of time intervals and comprises means for identifying a highest persistent heart rate over said series of defined time intervals.

6. A cardiac pacer according to claim 1 or claim 2 or claim 3 or claim 4 wherein said drop detecting means comprises means for detecting a drop in spontaneous heart rate from said highest persistent heart rate, of greater than a defined drop size.

7. A cardiac pacer according to claim 6 further comprising means for detecting a drop in spontaneous heart rate to a rate below a defined drop rate and wherein said means for causing said pulse generator means to deliver pacing pulses at a second pacing rate comprises means for causing said pulse generator means to deliver pacing pulses at said second pacing rate in response to a said detected rapid drop in spontaneous heart rate in conjunction with a said detected drop in spontaneous heart rate below said drop rate.

8. A cardiac pacer comprising:

means for detecting depolarizations of a heart;

means for determining spontaneous heart depolarization rate;

pulse generating means for delivering cardiac pacing pulses at a first pacing rate;

drop detecting means for detecting a rapid drop in spontaneous heart depolarization rate;

means responsive to a said detected rapid drop in spontaneous heart depolarization rate for causing said pulse generator means to deliver pacing pulses at a second pacing rate higher than said first pacing rate;

means for defining time periods associated with sleeping; and

means for disabling said drop detection means during said time periods associated with sleeping.

9. A pacer according to claim 8, wherein said means for defining time periods associated with sleeping comprises means for defining a 24 hour cycle and means for defining said periods associated with sleeping as part of said 24 hour cycle.

10. A cardiac pacer comprising:

means for detecting heart depolarizations;

means for storing heart depolarization intervals;

means for determining spontaneous heart depolarization rate;

pulse generating means for delivering cardiac pacing pulses at a first pacing rate;

rapid rate drop detecting means comprising means for storing a single column or row of a look-up table relating drop sizes and stored heart depolarization intervals to defined changes in depolarization interval such that only a said column or row associated with said selected drop size is stored, means for selecting a said defined change in depolarization interval as a function of a said stored depolarization interval, and means for identifying a rapid rate drop in response to an increase in heart depolarization interval from said stored depolarization interval, of greater than said selected change in depolarization interval; and

means responsive to a said identified rapid rate drop for causing said pulse generator means to deliver pacing pulses at a second pacing rate higher than said first pacing rate.

11. A cardiac pacer according to claim 10 further comprising:

means for defining a drop rate independent of determined spontaneous heart rate and means for detecting a drop in spontaneous heart rate to a rate below said defined drop rate and wherein said means for causing said pulse generator means to deliver pacing pulses at a second pacing rate comprises means for causing said pulse generator means to deliver pacing pulses at said second pacing rate in response to a said detected rapid drop in spontaneous heart rate in conjunction with a said detected drop in spontaneous heart rate below said defined drop rate.

12. A cardiac pacer comprising:

means for detecting depolarizations of a heart chamber;

pulse generating means for delivering cardiac pacing pulses at a first pacing rate in absent detected depolarizations of said heart chamber;

means responsive to generation of a series of pacing pulses at said first pacing rate without intervening detected depolarizations of said chamber, for temporarily causing said pulse generating means to generate pacing pulses at a second pacing rate in excess of said first pacing rate.

13. A cardiac pacer according to claim 12 wherein said responsive means comprises means responsive to generation of a predetermined number of pacing pulses at said first pacing rate.

14. A cardiac pacer according to claim 12 wherein said responsive means comprises means for causing said pulse generating means to generate pacing pulses at said second pacing rate for a predetermined time period and means for thereafter causing said pulse generating means to gradually decrement the rate of pacing pulses generated from said second rate to said first rate.

15. A device as set forth in claim 12 wherein said means responsive to detection of pacing pulses comprises;

means to count pacing pulses and for generating a signal value representative of said count, and

means to determine if said count of pacing pulses exceeds a predetermined value wihtin a predetermined period of time, and if so to generate a signal to increase the pacing rate such that said device will respond so as to increase the pacing rate, without requiring a drop determination.

16. A device as set forth in claim 15 wherein said means to count pacing pulses signal value representative of said count comprises a total of all pacing pulses counted and said means to count comprises:

means for CAP sensing and means for CVP sensing and means responsive to device mode such that when said device is in DDI mode both said means for CAP and said means for CVP sensing contribute count value signals to said signal value representative of said count but when in DDD mode only CAP sensing but not CAP contribute count value signals to said signal value representative of said count.

17. A method of cardiac pacing, comprising:

detecting depolarizations of a heart;

determining spontaneous heart depolarization rate;

delivering cardiac pacing pulses to said heart at a first pacing rate;

detecting a rapid drop in spontaneous depolarization rate of said heart by identifying a highest persistent heart rate over a limited time interval and determining whether said spontaneous heart depolarization rate has dropped more than a defined amount from said highest persistent heart rate; and

in response to a detected rapid drop in spontaneous heart depolarization rate, delivering pacing pulses at a second pacing rate higher than said first pacing rate.

18. A method according to claim 17 wherein detecting said highest persistent heart rate comprises identifying a fastest sequence of a predetermined number of beats, during said limited time interval.

19. A method according to claim 18 wherein said detecting said highest persistent heart rate comprises identifying a fastest sequence of two beats, during said limited time interval.

20. A method according to claim 19 wherein detecting said highest persistent heart rate comprises identifying the rate of the slowest of said beats in said fastest sequence of two beats, as said highest persistent heart rate.

21. A method according to claim 18 or claim 19 or claim 20 wherein detecting said highest persistent heart rate comprises defining a series of time intervals and identifying a highest persistent heart rate, over said series of defined time intervals.

22. A method according to claim 17 or claim 18 or claim 19 or claim 20 wherein detecting a rapid drop comprises detecting a drop in spontaneous heart rate from said highest persistent heart rate, of greater than a defined drop size.

23. A method according to claim 22, further comprising detecting a drop in spontaneous heart rate to a rate below a defined drop rate and wherein said step of delivering pacing pulses at a second pacing rate comprises delivering pacing pulses at said second pacing rate in response to a detected rapid drop in spontaneous heart rate in conjunction with a detected drop in spontaneous heart rate below said drop rate.

24. A method of cardiac pacing, comprising:

defining time periods associated with sleeping;

detecting depolarizations of a heart;

delivering cardiac pacing pulses at a first pacing rate;

detecting a rapid drop in spontaneous heart depolarization rate during time periods outside of said time periods associated with sleeping; and

responsive to a detected rapid drop in spontaneous heart depolarization rate, delivering pacing pulses at a second pacing rate higher than said first pacing rate.

25. A method according to claim 24, wherein defining time periods associated with sleeping comprises defining a 24 hour cycle and defining said periods associated with sleeping as part of said 24 hour cycle.

26. A method of cardiac pacing, comprising:

detecting depolarizations of a heart chamber;

delivering cardiac pacing pulses at a first pacing rate absent detected depolarizations of said heart chamber;

responsive to delivery of a series of pacing pulses at said first pacing rate without intervening detected depolarizations of said chamber, temporarily delivering cardiac pacing pulses at a second pacing rate in excess of said first pacing rate.

27. A method according to claim 26 wherein said step of temporarily delivering cardiac pacing pulses at said second pacing rate comprises delivering cardiac pacing pulses at said second pacing rate responsive to delivery of a predetermined number of pacing pulses at said first pacing rate.

28. A method according to claim 26, further comprising delivering pacing pulses while gradually decrementing rate of delivery of said pacing pulses from said second pacing rate to said first pacing rate.