Pacemaker with vasovagal syncope detection

Claim 2

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.

Claim 3

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.

Claim 4

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.

Claim 5

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.

Claim 6

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.

Claim 7

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.

Claim 8

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.

Claim 9

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.

Claim 10

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.

Claim 11

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.

Claim 12

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.

Claim 13

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.

Claim 14

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.

Claim 15

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.

Claim 16

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.

Claim 17

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.

Claim 18

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.

Claim 19

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.

Claim 20

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.

Claim 23

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.

Claim 24

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.

Claim 25

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.

Claim 26

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.

Claim 27

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.

Claim 28

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.

Claim 31

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.

Claim 34

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.

Claim 35

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.