Synchronous pacemaker with AV interval optimization
First Claim
1. An implantable cardiac pacing system capable of delivering atrial pace signals at a determined pacing rate and synchronously generating ventricular pace signals at a determined AV delay following delivery of atrial pacing signals and including an AV delay optimizing subsystem, said AV delay optimizing subsystem comprising:
- test means for initiating a test to determine an optimal AV delay corresponding to a pacing rate at about a lower rate limit (LRL);
rate means for setting a cardiac pacing rate at or near the LRL;
AV delay means for varying a AV delay interval value to each one of a plurality of respective AV values and for maintaining the AV delay interval value at each said respective AV value for a time t;
QT means operative during the time t of each maintained AV delay value for measuring variation of QT over said time t and for determining a QT differential (QTD) over said time t; and
optimizing means for determining the optimal AV delay, wherein said optimal AV delay corresponds to a minimal QTD, and for programming said optimal AV delay as an operating AV delay.
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Accused Products
Abstract
A system and method for use in an implanted cardiac pacing device, whereby an optimal AV delay is determined at or near lower rate (pacing) limit (LRL) by determining measuring the variance, or instability, of the QT interval for a set of intervals. In one embodiment, asynchronous “LRL pacing” with a first programmed AV delay determines a measure of QT variance. The difference between the maximum QT and the minimum QT is expressed as QT difference (QTD). For each programmed AV delay the QT variance is again measured and the optimal AV delay produces minimum QTD. In another embodiment, AV delay is modulated around base values for a time. The difference between QT for the modulated AV and for the base AV (dQT) is measured at each base value, and the optimal AV delay corresponds to the smallest dQT.
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Citations
52 Claims
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1. An implantable cardiac pacing system capable of delivering atrial pace signals at a determined pacing rate and synchronously generating ventricular pace signals at a determined AV delay following delivery of atrial pacing signals and including an AV delay optimizing subsystem, said AV delay optimizing subsystem comprising:
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test means for initiating a test to determine an optimal AV delay corresponding to a pacing rate at about a lower rate limit (LRL);
rate means for setting a cardiac pacing rate at or near the LRL;
AV delay means for varying a AV delay interval value to each one of a plurality of respective AV values and for maintaining the AV delay interval value at each said respective AV value for a time t;
QT means operative during the time t of each maintained AV delay value for measuring variation of QT over said time t and for determining a QT differential (QTD) over said time t; and
optimizing means for determining the optimal AV delay, wherein said optimal AV delay corresponds to a minimal QTD, and for programming said optimal AV delay as an operating AV delay. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An implantable pacing system for pacing a patient'"'"'s heart, having means for generating and delivering atrial pace signals at a determined pacing rate and means for generating ventricular pulses at a determined AV delay following an atrial pace event, and including an AV optimizing subsystem, said AV optimizing subsystem comprising:
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test means for initiating a test to determine an optimal AV delay corresponding to a pacing rate near a lower rate limit (LRL);
rate means for setting pacing rate near the LRL;
AV delay means for providing a set of respective base values of the AV delay;
setting means for setting a base value of each of the set of respective base values of the AV delay to each respective one of said set of base values and maintaining said base value for a predetermined duration, the test comprising a duration for each of the set of base values;
modulation means for modulating discrete delay intervals to a plurality of test AV delay values, wherein said plurality of test AV delay values are near each of the set of base values during each said duration;
QT variation means operative during each said duration for determining a change in QT (dQT) during the performance of the modulating function by the modulation means for each of the set of base values;
minimum means for determining the minimum dQT from a set of dQT values derived from the set of base values; and
optimizing means for setting an optimal AV to the base AV value corresponding to said minimum dQT. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of finding an optimal AV delay at or about a lower rate limit (LRL), for use in an implantable pacemaker in a A-V synchronous mode, comprising:
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delivering pacing stimulus at about a LRL;
setting a test AV delay to at least one predetermined base AV delay value at or near a base AV delay value for a predetermined duration;
obtaining an instability response for each cardiac cycle during said predetermined duration;
calculating a metric of the instability response during said predetermined duration; and
determining whether said test AV delay is optimal as a function of said instability response. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An implantable pacing device having structure to support a dual chamber synchronous pacing modality, comprising a system for optimizing an operating AV delay, said system comprising:
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T wave variation means for measuring T wave variation over a short time duration for each of a plurality of predetermined values of AV delay; and
optimizing means for determining a predetermined value of AV delay for which the least T wave variation was found, and for setting AV delay as said determined value. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41)
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42. A method of testing to determine the optimal value of an operating AV delay for use at about a lower rate limit (LRL) in a cardiac pacing device, comprising:
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measuring T wave variations over a short time duration for a plurality of predetermined values of AV delay;
comparing said T wave variations and determining a minimum T wave variation and an AV delay corresponding thereto; and
programming an operating AV delay with the AV delay corresponding to said minimum T wave variation. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51)
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52. A computer readable medium for storing executable instructions for performing a method of testing to determine the optimal value of an operating AV delay for use at about a lower rate limit (LRL) in a cardiac pacing device, comprising:
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instructions for measuring T wave variations over a short time duration for a plurality of predetermined values of AV delay;
instructions for comparing said T wave variations and determining a minimum T wave variation and an AV delay corresponding thereto; and
instructions for programming an operating AV delay with the AV delay corresponding to said minimum T wave variation.
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Specification