Method and apparatus for dual chamber cardiac pacing

Claim 5

A method according to claim 2, further comprising the step of counting sequentially delivered ventricular pacing pulses and wherein said extending step comprises extending said A-V escape intervals in response to counting a predetermined number of sequentially delivered ventricular pacing pulses.

Claim 6

A method according to claim 2, wherein said extending step comprises extending said A-V escape intervals up to a predefined maximum A-V escape interval, and further comprising the step of preventing subsequent extensions of said A-V escape intervals for a period of time in response to failure of a ventricular depolarization to occur within said maximum A-V escape interval.

Claim 9

A method according to claim 5, wherein said employing step comprises employing said defined A-V escape interval as subsequent A-V escape intervals.

Claim 10

A method according to claim 5, further comprising the step of measuring atrial--ventricular conduction time of said heart, and wherein said employing step comprises the steps of: deriving a first offset interval based on relative durations of said defined A-V escape interval and said measured atrial--ventricular conduction time; measuring atrial--ventricular conduction time of a ventricular depolarization occurring within a first one of said subsequent A-V escape intervals; and defining duration of a second, later one of said subsequent A-V escape intervals based on said first offset interval and said atrial--ventricular conduction time measured within first one of said subsequent A-V escape intervals.

Claim 11

A method according to claim 1 or claim 2, further comprising the steps of sensing spontaneous atrial depolarizations and delivering atrial pacing pulses and wherein said step of defining duration of a subsequent A-V escape interval comprises defining a first A-V escape interval duration to be employed following spontaneous atrial depolarizations and a second A-V escape interval to be employed following delivered atrial pacing pulses.

Claim 12

A method according to claim 1 or claim 2, wherein said step of defining duration of a subsequent A-V escape interval comprises determining heart rate and defining duration of a subsequent said A-V escape interval based on said first offset interval, said atrial--ventricular conduction time measured within said extended A-V escape interval, and said determined heart rate.

Claim 13

Apparatus for pacing a heart, comprising: means for sensing atrial depolarizations; means for defining a first offset interval; means for defining A-V escape intervals following atrial depolarizations; means for sensing ventricular depolarizations of said heart; means for delivering ventricular pacing pulses at the expirations of said A-V escape intervals in the absence of ventricular depolarizations during said A-V escape intervals; means for extending durations of said A-V escape intervals until a ventricular depolarization falls within a said extended A-V escape interval; means for measuring atrial--ventricular conduction time of a sensed ventricular depolarization occurring within a said extended A-V escape interval; and means for defining duration of a subsequent said A-V escape interval by subtracting said first offset interval and said atrial--ventricular conduction time measured within said extended A-V escape intervail; wherein said means for extending said A-V escape intervals comprises means for extending said A-V escape intervals up to a predefined maximum A-V escape interval, and further comprises means for preventing subsequent extensions of said A-V escape intervals for a period of time in response to failure of a ventricular depolarization to occur within said maximum A-V escape interval.

Claim 14

Apparatus for pacing a heart, comprising: means for sensing atrial depolarizations; means for defining a first offset interval; means for defining A-V escape intervals following atrial depolarizations; means for sensing ventricular depolarizations of said heart; means for delivering ventricular pacing pulses at the expirations of said A-V escape intervals in the absence of ventricular depolarizations during said A-V escape intervals; means for extending durations of said A-V escape intervals until a ventricular depolarization falls within a said extended A-V escape interval; means for measuring atrial--ventricular conduction time of a sensed ventricular depolarization occurring within a said extended A-V escape interval; and means for defining duration of a subsequent said A-V escape interval by subtracting said first offset interval and said atrial--ventricular conduction time measured within said extended A-V escape intervail; wherein said means for extending said A-V escape intervals comprises means for extending said A-V escape intervals up to a predefined maximum A-V escape interval, and further comprises means for preventing subsequent extensions of said A-V escape intervals for a period of time in response to failure of a ventricular depolarization to occur within said maximum A-V escape interval.

Claim 15

A apparatus according to claim 10, further comprising means for counting sequentially delivered ventricular pacing pulses and wherein said means for extending said A-V escape intervals comprises extending said A-V escape intervals in response to counting a predetermined number of sequentially delivered ventricular pacing pulses.

Claim 16

Apparatus according to claim 10, wherein said means for extending said A-V escape intervals comprises means for extending said A-V escape intervals up to a predefined maximum A-V escape interval, and further comprises means for preventing subsequent extensions of said A-V escape intervals for a period of time in response to failure of a ventricular depolarization to occur within said maximum A-V escape interval.

Claim 17

Apparatus according to claim 10, further comprising means for delivering atrial pacing pulses and wherein said means for defining duration of a subsequent A-V escape interval comprises means for defining a first A-V escape interval duration to be employed following a sensed spontaneous atrial depolarizations and means for defining a second A-V escape interval to be employed following delivered atrial pacing pulses.

Claim 18

Apparatus according to claim 10, wherein said means for defining duration of a subsequent A-V escape interval comprises means for determining heart rate and means for defining duration of a subsequent said A-V escape interval based on said first offset interval, said atrial--ventricular conduction time measured within said extended A-V escape interval, and said determined heart rate.

Claim 19

Apparatus for pacing a heart, comprising: means for sensing atrial and ventricular depolarizations: means for measuring atrial--ventricular conduction time of said heart; means for delivering ventricular pacing pulses capable of completely capturing said heart's ventricles absent concurrent spontaneous depolarizations of said ventricles; means for determining a time interval following an atrial depolarization of said heart, such that a said ventricular pacing pulse delivered at expiration of said time interval results in complete ventricular capture of said heart; means for deriving a first offset interval based on relative durations of said determined time interval and said measured atrial--ventricular conduction time; means for defining A-V escape intervals following atrial depolarizations; means for sensing ventricular depolarizations of said heart; delivering ventricular pacing pulses at the expirations of said A-V escape intervals absent sensed ventricular depolarizations during said A-V escape intervals; means for measuring atrial--ventricular conduction time of a ventricular depolarization occurring within a said A-V escape interval; and means for defining duration of a subsequent said A-V escape interval based on said first offset interval and said atrial--ventricular conduction time measured within said A-V escape interval.

Claim 20

Apparatus for pacing a heart, comprising: means for sensing atrial and ventricular depolarizations: means for measuring atrial--ventricular conduction time of said heart; means for delivering ventricular pacing pulses capable of completely capturing said heart's ventricles absent concurrent spontaneous depolarizations of said ventricles; means for determining a time interval following an atrial depolarization of said heart, such that a said ventricular pacing pulse delivered at expiration of said time interval results in complete ventricular capture of said heart; means for deriving a first offset interval based on relative durations of said determined time interval and said measured atrial--ventricular conduction time; means for defining A-V escape intervals following atrial depolarizations; means for sensing ventricular depolarizations of said heart; delivering ventricular pacing pulses at the expirations of said A-V escape intervals absent sensed ventricular depolarizations during said A-V escape intervals; means for measuring atrial--ventricular conduction time of a ventricular depolarization occurring within a said A-V escape interval; and means for defining duration of a subsequent said A-V escape interval based on said first offset interval and said atrial--ventricular conduction time measured within said A-V escape interval.

Claim 21

Apparatus for pacing a heart, comprising: means for sensing atrial and ventricular depolarizations: means for measuring atrial--ventricular conduction time of said heart; means for delivering ventricular pacing pulses capable of completely capturing said heart's ventricles absent concurrent spontaneous depolarizations of said ventricles; means for determining a time interval following an atrial depolarization of said heart, such that a ventricular pacing pulse delivered at expiration of said time interval results in complete ventricular capture of said heart; means for deriving a first offset interval based on relative durations of said determined time interval and said measured atrial--ventricular conduction time; means for defining an A-V escape intervals following atrial depolarizations; means for sensing ventricular depolarizations of said heart; means for delivering ventricular pacing pulses at the expirations of said A-V escape intervals absent ventricular depolarizations during said A-V escape intervals; means for extending durations of said A-V escape intervals until a sensed ventricular depolarization falls within a said extended A-V escape interval; means for measuring atrial--ventricular conduction time of a sensed ventricular depolarization occurring within a said extended A-V escape interval; and means for defining duration of a subsequent said A-V escape interval based on said first offset interval and said atrial--ventricular conduction time measured within said extended A-V escape interval.

Claim 22

Apparatus for pacing a heart, comprising: means for sensing atrial and ventricular depolarizations: means for measuring atrial--ventricular conduction time of said heart; means for delivering ventricular pacing pulses capable of completely capturing said heart's ventricles absent concurrent spontaneous depolarizations of said ventricles; means for determining a time interval following an atrial depolarization of said heart, such that a ventricular pacing pulse delivered at expiration of said time interval results in complete ventricular capture of said heart; means for deriving a first offset interval based on relative durations of said determined time interval and said measured atrial--ventricular conduction time; means for defining an A-V escape intervals following atrial depolarizations; means for sensing ventricular depolarizations of said heart; means for delivering ventricular pacing pulses at the expirations of said A-V escape intervals absent ventricular depolarizations during said A-V escape intervals; means for extending durations of said A-V escape intervals until a sensed ventricular depolarization falls within a said extended A-V escape interval; means for measuring atrial--ventricular conduction time of a sensed ventricular depolarization occurring within a said extended A-V escape interval; and means for defining duration of a subsequent said A-V escape interval based on said first offset interval and said atrial--ventricular conduction time measured within said extended A-V escape interval.

Claim 23

Apparatus for pacing a heart, comprising: means for sensing atrial and ventricular depolarizations: means for delivering a ventricular pacing pulse to said heart to induce complete ventricular capture; means for delivering ventricular pacing pulses capable of completely capturing said heart's ventricles absent concurrent spontaneous depolarizations of said ventricles; means for monitoring waveforms of ventricular depolarizations: means for determining a ventricular depolarization waveform indicative of complete ventricular capture; means for defining A-V escape intervals following atrial depolarizations; means for delivering said ventricular pacing pulses at expirations of said A-V escape intervals; means for varying durations of said A-V intervals while monitoring waveforms of ventricular depolarizations following said ventricular pacing pulses; means responsive to said monitoring means, for identifying a said A-V escape interval duration such that a ventricular pacing pulse delivered at expiration of said identified A-V escape interval duration results in complete ventricular capture of said heart; and means for employing said identified A-V escape interval duration to define durations of subsequent said A-V escape intervals.

Claim 24

Apparatus for pacing a heart, comprising: means for sensing atrial and ventricular depolarizations: means for delivering a ventricular pacing pulse to said heart to induce complete ventricular capture; means for delivering ventricular pacing pulses capable of completely capturing said heart's ventricles absent concurrent spontaneous depolarizations of said ventricles; means for monitoring waveforms of ventricular depolarizations: means for determining a ventricular depolarization waveform indicative of complete ventricular capture; means for defining A-V escape intervals following atrial depolarizations; means for delivering said ventricular pacing pulses at expirations of said A-V escape intervals; means for varying durations of said A-V intervals while monitoring waveforms of ventricular depolarizations following said ventricular pacing pulses; means responsive to said monitoring means, for identifying a said A-V escape interval duration such that a ventricular pacing pulse delivered at expiration of said identified A-V escape interval duration results in complete ventricular capture of said heart; and means for employing said identified A-V escape interval duration to define durations of subsequent said A-V escape intervals.

Claim 25

Apparatus according to claim 17, wherein said employing means comprises means for employing said identified A-V escape interval duration as a subsequent said A-V escape intervals.

Claim 26

Apparatus according to claim 17, further means for measuring atrial--ventricular conduction time of said heart, and wherein said employing means comprises: means for deriving a first offset interval based on relative durations of said identified A-V escape interval and said measured atrial--ventricular conduction time; means for measuring atrial--ventricular conduction time of a ventricular depolarization occurring within a first one of said subsequent A-V escape intervals; and means for defining duration of a second, later one of said subsequent A-V escape intervals based on said first offset interval and said atrial--ventricular conduction time measured within first one of said subsequent A-V escape intervals.