Atrial rate determination and atrial tachycardia detection in a dual-chamber implantable pacemaker
First Claim
1. A method of determining the atrial rate of a patient in a dual-chamber implantable pacemaker, the pacemaker including:
- sensing means for sensing P-waves;
pulse generation means for generating V-pulses;
timing means for defining a PV delay that defines a time interval allowed by the pacemaker between a sensed P-wave and a generated V-pulse, a basic pacing interval that defines a pacing rate, and an absolute refractory period following generation of a V-pulse during which P-waves are not sensed;
the method comprising;
(a) sensing a series of consecutive P-waves to determine an atrial rate;
(b) determining if the atrial rate is within an atrial rate zone where P-waves may be hidden within the absolute refractory period;
(c) if hidden P-waves may exist, examining that portion of the basic pacing interval corresponding to the absolute refractory period to determine if a hidden P-wave lies therewithin; and
(d) if a hidden P-wave is uncovered within the absolute refractory period, including such hidden P-wave within the series of consecutive P-waves sensed in step (a) to redetermine the atrial rate;
whereby the atrial rate is determined based on the inclusion of such hidden P-wave.
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Accused Products
Abstract
An implantable pacemaker accurately senses the regular atrial rhythm even though some portions of the atrial rhythm, e.g., every other P-wave, may potentially be masked or hidden within the ventricular absolute refractory period. Such sensing includes unmasking or uncovering any hidden P-waves, thereby allowing an accurate atrial rate to be determined. The hidden P-waves are uncovered by: changing the PV delay, not tracking a sensed P-wave, or comparing the incoming morphology of the atrial channel signal to a prior stored baseline morphology signal. The accurate atrial rate, once determined, allows the presence of an atrial tachycardia to be reliably confirmed, thereby enabling appropriate atrial anti-tachycardia pacing (ATP) procedures to be invoked, or mode switching from an atrial synchronous mode of operation, e.g., DDD, to a non-atrial synchronous mode, e.g., VVIR.
135 Citations
44 Claims
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1. A method of determining the atrial rate of a patient in a dual-chamber implantable pacemaker, the pacemaker including:
- sensing means for sensing P-waves;
pulse generation means for generating V-pulses;
timing means for defining a PV delay that defines a time interval allowed by the pacemaker between a sensed P-wave and a generated V-pulse, a basic pacing interval that defines a pacing rate, and an absolute refractory period following generation of a V-pulse during which P-waves are not sensed;
the method comprising;(a) sensing a series of consecutive P-waves to determine an atrial rate; (b) determining if the atrial rate is within an atrial rate zone where P-waves may be hidden within the absolute refractory period; (c) if hidden P-waves may exist, examining that portion of the basic pacing interval corresponding to the absolute refractory period to determine if a hidden P-wave lies therewithin; and (d) if a hidden P-wave is uncovered within the absolute refractory period, including such hidden P-wave within the series of consecutive P-waves sensed in step (a) to redetermine the atrial rate;
whereby the atrial rate is determined based on the inclusion of such hidden P-wave. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
- sensing means for sensing P-waves;
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30. A method of uncovering hidden P-waves that occur during the absolute refractory period following a ventricular stimulus of a dual-chamber implantable pacemaker, the pacemaker including:
- sensing means for sensing P-waves;
pulse generation means for generating V-pulses;
timing means for defining a PV delay that defines a time interval allowed by the pacemaker between a sensed P-wave and a generated V-pulse, a basic pacing interval that defines a pacing rate, and an absolute refractory period following generation of a V-pulse during which P-wave sensing is not reliable;
the method comprising;moving the absolute refractory period away from that portion of the basic pacing interval wherein hidden P-waves may lie; and sensing whether any P-waves occur within that portion of the cardiac cycle from which the absolute refractory period has been moved, and if so, identifying such sensed P-waves as hidden P-waves. - View Dependent Claims (31, 32, 33, 34, 35)
- sensing means for sensing P-waves;
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36. A method of determining the atrial rate of a patient having a dual-chamber pacemaker, the pacemaker including:
- sensing means for sensing P-waves;
pulse generation means for generating V-pulses;
timing means for defining a basic pacing interval that defines a pacing rate and a maximum tracking rate (MTR) interval (MTRI) that limits the rate at which V-pulses are generated;
the method comprising;determining if V-pulses are generated at a rate that is limited by the MTR, and if so sensing P-waves that occur during the MTRI and classifying such P-waves as non-tracked P-waves, sensing P-waves that occur outside the MTRI and classifying such P-waves as tracked P-waves, and determining the atrial rate as a function of a P-to-P interval separating the consecutive sensed P-waves, whether such consecutive P-waves are non-tracked or tracked; whereby the consecutive sensed P-waves define the determined atrial rate. - View Dependent Claims (37)
- sensing means for sensing P-waves;
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38. A method for determining the presence of an atrial tachycardia in a patient having a dual-chamber pacemaker, the pacemaker comprising:
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means for defining an atrial tachycardia detection rate (ATDR); sensing means for sensing P-waves; pulse generation means for generating a ventricular stimulation pulse (V-pulse) a prescribed time delay following a sensed P-wave; and timing means for defining and generating a fixed, recurring, free-running atrial lock interval (ALI*) that is independent from any sensed cardiac events, the ALI* thus comprising a sequence of recurring fixed periods of length ALI*, the method comprising; determining in more than one V-pulse would be generated in any given ALI* period, and if so, inhibiting all but the first V-pulse in any given ALI* period, measuring a P-to-P interval (PPI) for each inhibited V-pulse as the time interval between a first sensed P-wave following which the inhibited V-pulse would have been generated and a second sensed P-wave immediately following the first sensed P-wave, determining if the PPI for i consecutive inhibited V-pulses corresponds to an atrial rate greater than the ATDR, where i is an integer greater than one, and if so declaring an atrial tachycardia condition to be present. - View Dependent Claims (39)
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40. A dual-chamber implantable pacemaker that detects atrial rate based on sensed P-waves, including sensed P-waves that are potentially hidden within an absolute refractory period, comprising:
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sensing means for sensing a series of consecutive P-waves; pulse generation means for generating V-pulses; timing means for defining a PV delay that defines a time interval allowed by the pacemaker between a sensed P-wave and a generated V-pulse, a basic pacing interval that defines a pacing rate, and an absolute refractory period following generation of a V-pulse during which P-waves are not sensed; control means for examining that portion of the basic pacing interval corresponding to the absolute refractory period to uncover any hidden P-waves that lie therewithin; and rate-determining means for determining a true atrial rate based on all sensed P-waves, including any uncovered hidden P-waves. - View Dependent Claims (41, 42)
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43. A mode-switching pacemaker that automatically switches modes based on an atrial rate sensed by the pacemaker comprising:
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sensing means for sensing a series of consecutive P-waves; pulse generation means for generating V-pulses; timing means for defining a PV delay that defines a time interval allowed by the pacemaker between a sensed P-wave and a generated V-pulse, a basic pacing interval that defines a pacing rate, and an absolute refractory period following generation of a V-pulse during which P-waves are not sensed; control means for operating the pacemaker in an atrial synchronous mode and for examining that portion of the basic pacing interval corresponding to the absolute refractory period to uncover any hidden P-waves that lie therewithin; rate-determining means for determining a true atrial rate based on all sensed P-waves, including any uncovered hidden P-waves; and mode switching means for switching the mode of the pacemaker to a non-atrial synchronous mode in the event the atrial rate determined by the rate-determining means exceeds a preset atrial tachycardia detection rate (ATDR). - View Dependent Claims (44)
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Specification