Upper rate response for implantable pacemaker based on atrial lock interval pacing
First Claim
1. A method of operating a dual-chamber pacemaker in a P-tracking mode that maintains synchrony between atrial and ventricular events for a higher percentage of the time when operating at upper rate limits, the pacemaker including means for sensing P-waves and R-waves, and means for generating V-pulses, the method comprising:
- tracking P-waves by generating a V-pulse one PV delay after sensing a P-wave, unless an R-wave is sensed prior to the end of the PV delay, in which case no V-pulse is generated, up to a first maximal tracking rate, whereby an instantaneous ventricular rate is limited by the first maximal tracking rate; and
limiting a maximal mean ventricular rate to a second maximal tracking rate, said second maximal tracking rate being less than the first maximal tracking rate.
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Accused Products
Abstract
Atrial lock interval pacing increases stroke volume and optimizes cardiac output by providing a modified P-wave tracking mode that tracks P-waves up to a maximum instantaneous tracking rate only for short periods of time, to provide a maximum instantaneous ventricular heart rate, yet limits the maximal mean (or average) ventricular rate over a longer period of time, to provide a safe target maximal average rate. Two main types or embodiments of modified P-wave tracking modes may be used. A first provides a sequence of timed intervals that begins upon sensing each P-wave. Such sequence may include, e.g.: (1) a PV interval; (2) a PVARP; (3) a Wenkebach interval; (4) an atrial lock interval; and (4) a P-track interval. P-waves are not tracked during the PV interval or PVARP. P-waves that occur during the Wenkebach or Atrial lock interval are tracked, but not in a conventional manner. P-waves that occur during the P-track interval are tracked in a conventional manner. A second modified P-wave tracking mode defines a maximum mean rate (MMR) interval. The MMR interval (MMRI) is an asynchronous free-running signal that is not synchronized to any cardiac cycle events. During each MMRI, the number of atrial or ventricular events that occur are noted. Ventricular stimulation pulses (V-pulses) are not generated if the resulting ventricular depolarization would represent the second ventricular depolarization of the current MMRI.
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Citations
45 Claims
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1. A method of operating a dual-chamber pacemaker in a P-tracking mode that maintains synchrony between atrial and ventricular events for a higher percentage of the time when operating at upper rate limits, the pacemaker including means for sensing P-waves and R-waves, and means for generating V-pulses, the method comprising:
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tracking P-waves by generating a V-pulse one PV delay after sensing a P-wave, unless an R-wave is sensed prior to the end of the PV delay, in which case no V-pulse is generated, up to a first maximal tracking rate, whereby an instantaneous ventricular rate is limited by the first maximal tracking rate; and limiting a maximal mean ventricular rate to a second maximal tracking rate, said second maximal tracking rate being less than the first maximal tracking rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of limiting the maximal mean ventricular rate of a pacemaker, the pacemaker including sensing means for sensing P-waves, pulse generation means for generating V-pulses, and timing means for defining timed intervals, the method comprising:
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generating a recurring cycle of maximum mean rate intervals (MMRI) of x seconds each that runs independent of any sensed events; tracking only a first sensed P-wave in each MMRI by;
(i) starting a PV delay upon the sensing of the first sensed P-wave in the MMRI, and (ii) generating a V-pulse at the conclusion of the PV interval; andnot tracking any subsequent sensed atrial events that occur during the MMRI.
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13. A method of limiting the maximal mean ventricular rate of a pacemaker, the pacemaker including sensing means for sensing P-waves and R-waves;
- pulse generation means for generating V-pulses; and
timing means for defining timed intervals; and
wherein an R-wave or a V-pulse comprises a ventricular event;
the method comprising;generating a recurring cycle of maximum mean rate intervals (MMRI) of x seconds each that runs independent of any sensed events; and allowing only one ventricular event in each MMRI.
- pulse generation means for generating V-pulses; and
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14. A method of operating a dual-chamber pacemaker in a P-tracking mode at upper rate limits, the pacemaker including means for sensing P-waves and R-waves, and means for generating V-pulses, the method comprising:
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tracking P-waves by generating a V-pulse one PV delay after sensing a P-wave up to a first upper rate limit, whereby an instantaneous ventricular rate is limited by the first upper rate limit; and limiting a maximal mean ventricular rate to a second upper rate limit that is less than the first upper rate limit, while allowing an instantaneous ventricular rate to exceed the second upper rate limit and approach the first upper rate limit. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. In a dual-chamber pacemaker, a system for increasing stroke volume at upper pacemaker rates, the pacemaker including means for sensing P-waves and R-waves, and means for generating V-pulses, the system comprising:
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P-wave tracking means for providing a ventricular rate that tracks sensed P-waves; upper rate limiting means for limiting the P-wave tracking means so that P-waves are instantaneously tracked up to a maximal tracking rate, thereby providing an instantaneous ventricular rate that tracks the sensed P-waves up to the maximal tracking rate; and average-rate limiting means for limiting an average ventricular rate to a value that is less than the maximal tracking rate. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A dual-chamber implantable pacemaker operable in a P-tracking mode, the pacemaker including means for sensing P-waves, and means for generating V-pulses, comprising:
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P-wave tracking means for providing a ventricular rate that tracks sensed P-waves; upper rate limiting means for limiting the P-wave tracking means so that P-waves are tracked only up to a maximal tracking rate; and means for limiting a maximal mean ventricular rate to a value that is less than the maximal tracking rate.
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30. A method of maintaining synchrony between atrial events and ventricular stimulation in an implantable pacemaker, the pacemaker having means for sensing atrial events, and means for generating a ventricular stimulation pulse (V-pulse), comprising:
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(a) generating a recurring cycle of tracking periods of T seconds each that runs independent of any sensed events; (b) tracking only a first sensed atrial event in each tracking period by;
(i) starting a PV interval upon the sensing of the first sensed atrial event in the tracking period, and (ii) generating a V-pulse at the conclusion of the PV interval; and(c) not tracking any subsequent sensed atrial events that occur during a tracking period wherein a first sensed atrial event has already been tracked; whereby the average rate of generating V-pulses in synchrony with sensed atrial events is 1/T pulses per second. - View Dependent Claims (31, 32)
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33. A method of maintaining synchrony between atrial events and ventricular stimulation in a dual-chamber implantable pacemaker, the pacemaker having means for sensing atrial events and ventricular events, and means for generating a ventricular stimulation pulse (V-pulse), said method comprising:
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(a) generating a recurring cycle of tracking periods of T seconds each that runs independent of any sensed events; (b) tracking a sensed atrial event in each tracking period by; (i) starting a PV interval upon the sensing of the sensed atrial event in the tracking period, (ii) generating a V-pulse at the conclusion of the PV interval when ventricular activity has not already occurred during the tracking period, and (iii) inhibiting the generation of a V-pulse at the conclusion of the PV interval when ventricular activity has already occurred during the tracking period; whereby the average rate of generating V-pulses in synchrony with sensed atrial events is 1/T pulses per second. - View Dependent Claims (34)
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35. A method of operating an implantable pacemaker to synchronize atrial depolarization with a paced ventricular depolarization, said pacemaker including means for sensing atrial and ventricular depolarizations, and means for generating a ventricular stimulation pulse (V-pulse) at a set time following the atrial depolarization, the V-pulse being adapted to force a ventricular depolarization, the method comprising the steps of:
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(a) defining a maximum mean rate interval (MMRI) that sets the fastest average rate at which the pacemaker is to pace a patient'"'"'s heart; (b) starting a recurring cycle of MMRI intervals by starting a first MMRI interval at any time, starting a second MMRI interval at the conclusion of the first MMRI interval, starting a third MMRI interval at the conclusion of the second MMRI interval, and so on, with an (n+1)th MMRI interval being started at the conclusion of an nth MMRI interval, where n is an integer, with the cycle of MMRI intervals thus established running independent of other timed or sensed events within the pacemaker; and (c) generating a V-pulse at the set time following the atrial depolarization no more than once during each MMRI interval. - View Dependent Claims (36, 37, 38)
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39. A dual-chamber implantable pacemaker comprising:
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sensing means for sensing an atrial depolarization (P-wave) and a ventricular depolarization (R-wave) within a patient'"'"'s cardiac cycle; pulse generating means for generating a ventricular stimulation pulse (V-pulse); control means for controlling the sensing means and pulse generating means so as to maximize the number of cardiac cycles during which the generation of a V-pulse is synchronized with atrial activity, said control means including; means for generating a PV interval that defines the time between a sensed P-wave and a V-pulse, means for inhibiting the generating of a V-pulse at the conclusion of the PV interval in the event an R-wave is sensed before the timing out of the PV interval, means for generating a cycle of maximum mean rate intervals (MMRI'"'"'s) that runs asynchronously relative to the sensing means and pulse generating means, with a new MMRI commencing at the conclusion of a prior MMRI, and means for preventing the generation of a V-pulse within a given MMRI of the cycle of MMRI'"'"'s if either an R-wave or V-pulse has already occurred within the given MMRI, whereby at most only one ventricular depolarization is caused by said pacemaker during each MMRI. - View Dependent Claims (40, 41, 42, 43, 44)
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45. A dual-chamber pacemaker for stimulating the heart of a patient, said pacemaker comprising:
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an atrial channel that includes means for sensing P-waves; a ventricular channel that includes means for sensing R-waves and means for generating and delivering ventricular stimulation pulses (V-pulses); control means for controlling the atrial channel and the ventricular channel to operate in a dual-chamber mode of operation, said control means comprising; timing means for defining a pacing cycle made up of a plurality of timed periods, said timed periods including a post ventricular atrial refractory period (PVARP) that begins with a ventricular event, said ventricular event comprising either a sensed R-wave or a generated V-pulse, and upper rate limiting means for limiting the maximum mean rate of the pacing cycle, the maximum rate being defined by a maximum mean rate interval (MTR), said upper rate limiting means comprising; means for generating a continuous MMRI sequence with one MMRI beginning immediately after the conclusion of a preceding MMRI, said MMRI sequence being asynchronous relative to said timing means, and means for limiting the number of V-pulses that may occur during each MMRI of the sequence to no more than one, whereby V-pulses may not be generated by the ventricular channel at a rate that is, on average, any faster than the maximum rate defined by the MMRI.
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Specification