Pacemaker and method for ventricular rate limit operation and termination of pacemaker mediated tachycardia
First Claim
1. A heart pacemaker, comprising:
- means for sensing electrical events that occur in the atrium of a heart;
means for sensing electrical events that occur in the ventricle of the heart;
means for selecting an atrial refractory period;
means for timing said atrial refractory period from detected electrical events of the ventricle;
means for pacing the ventricle of the heart in synchronism with atrial events detected outside said atrial refractory period;
means for selecting a value of a ventricular rate limit that defines the maximum rate at which the ventricle can be paced;
said means for pacing the ventricle including means for pacing the ventricle at a rate that does not exceed said value of the ventricular rate limit;
means for counting a preselected number of successive atrial synchronous paces of the ventricle at the ventricular rate limit; and
means for preventing a pace of the ventricle in response to an atrial event sensed outside said atrial refractory period and after said preselected number of successive atrial synchronous paces of the ventricle is counted.
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Accused Products
Abstract
A microprocessor-controlled pacemaker is programmed to extend an atrial refractory interval in response to the detection of events which could initiate a pacer sustained tachycardia. The extended atrial refractory interval ensures that a spurious atrial event resulting from retrograde conduction of a ventricle event will not cause a pace of the ventricle. The pacer is also programmed to break out of a pacer sustained tachycardia by inhibiting a ventricular pace when a predefined number of previous successive ventricular paces have occurred at the ventricular rate limit. The pacer is further programmed so that in response to a high atrial rate, the ventricle is paced at either a predefined ventricular upper rate limit value or at a rate limit value that is decremented to a fallback rate limit value. The pacer further increases the VA interval when the ventricle is paced at the ventricular rate limit. The pacer is also programmed to show Wenckebach behavior and thereby occasionally drop a ventricular pace in response to an atrial rate that exceeds the ventricular rate limit. The pacer resets the defined ventricular rate limit to an upper rate limit value when two successive ventricular paces are provided at a rate less than the defined ventricular rate limit. A nonphysiological interval is defined after an atrial pace. If a ventricular event is detected during the nonphysiological interval, the ventricle is paced at a predefined time period following the initiating atrial event.
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Citations
38 Claims
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1. A heart pacemaker, comprising:
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means for sensing electrical events that occur in the atrium of a heart; means for sensing electrical events that occur in the ventricle of the heart; means for selecting an atrial refractory period; means for timing said atrial refractory period from detected electrical events of the ventricle; means for pacing the ventricle of the heart in synchronism with atrial events detected outside said atrial refractory period; means for selecting a value of a ventricular rate limit that defines the maximum rate at which the ventricle can be paced; said means for pacing the ventricle including means for pacing the ventricle at a rate that does not exceed said value of the ventricular rate limit; means for counting a preselected number of successive atrial synchronous paces of the ventricle at the ventricular rate limit; and means for preventing a pace of the ventricle in response to an atrial event sensed outside said atrial refractory period and after said preselected number of successive atrial synchronous paces of the ventricle is counted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A heart pacemaker, comprising:
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means for detecting electrical events in the atrium of a heart; means for selecting a ventricular rate limit; means for pacing the ventricle of the heart in synchronism with detected atrial events at a rate that does not exceed said ventricular rate limit; means for defining a preselected VA interval when said ventricle is paced at a rate less than said ventricular rate limit; means for defining an increased VA interval when said ventricle is paced at said ventricular rate limit; and means for timing the VA interval following each pace of the ventricle. - View Dependent Claims (13, 14, 15, 16)
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17. A method for operating a pacemaker to avoid pacemaker sustained tachycardia, comprising the steps of:
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selecting an atrial refractory interval; sensing electrical events in the ventricle of the heart; timing the atrial refractory interval from sensed ventricular events; selecting an AV delay interval; sensing an electrical event in the atrium of the heart outside said atrial refractory interval; timing out said AV delay interval from the sensed atrial event; selecting a value for a ventricular rate limit; pacing the ventricle at the end of the AV delay interval if no ventricular event is sensed during the AV delay interval and if the pace will not exceed the defined ventricular rate limit; pacing the ventricle at the ventricular rate limit if a pace at the end of the AV delay interval would exceed the ventricular rate limit; counting successive paces of the ventricle at the ventricular rate limit; identifying a pacemaker sustained tachycardia condition by detecting a predefined number of successive ventricular paces at the ventricular rate limit; and inhibiting a pace of the ventricle and thereby terminating the pacemaker sustained tachycardia when the pacemaker sustained tachycardia condition is detected. - View Dependent Claims (18, 25)
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19. A method for operating a pacemaker to avoid a pacemaker sustained tachycardia, comprising the steps of:
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selecting a value for a ventricular rate limit; sensing electrical events in the ventricle of the heart; sensing electrical events in the atrium of the heart; timing out a predefined AV delay interval from each sensed atrial event; pacing the ventricle at the end of the AV delay interval if no ventricular event is sensed during the AV delay interval and if the pace will not exceed the defined ventricular rate limit; pacing the ventricle at the ventricular rate limit if a pace at the end of the AV delay interval would exceed the ventricular rate limit; selecting a VA time period when the ventricle is paced at less than the ventricular rate limit; increasing the VA time period by a preselected amount when the ventricle is paced at the ventricular rate limit; timing the VA time period from a sensed or paced ventricular event; and pacing the atrium if an atrial event is not sensed within the VA time period. - View Dependent Claims (20)
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21. A pacemaker for sensing electrical events in the atrium and ventricle of a heart and pacing the heart, comprising:
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means for sensing electrical events in the atrium; means for sensing electrical events in the ventricle; means for selecting an artifact sensing interval; means for timing the interval from a predetermined start time after an electrical event is sensed in the atrium; and means for pacing the ventricle at a predefined time after the end of the artifact sensing interval when at least one ventricular event is sensed during the artifact sensing interval. - View Dependent Claims (22)
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23. A method for operating a pacemaker, comprising the steps of:
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sensing atrial and ventricular events; timing at least one predefined blanking interval from a sensed atrial event; preventing the sensing of ventricular events during the timing of the blanking interval; timing a predefined artifact sensing interval from the end of the blanking interval; and pacing the ventricle at a predefined time after the end of the artifact sensing interval when at least one ventricular event is sensed during the artifact sensing interval.
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24. A pacemaker for preventing a pacemaker sustained tachycardia, comprising:
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means for sensing electrical signals of the ventricle of a heart; means for timing a preselected atrial refractory interval after sensing a ventricular signal; means for sensing electrical signals of the atrium of the heart; means for pacing the ventricle in synchronism with atrial signals that occur outside said atrial refractory interval; means for detecting a condition indicative of a pacemaker sustained tachycardia; and means for inhibiting a pace of the ventricle to terminate the detected pacemaker sustained tachycardia. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A heart pacemaker, comprising:
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means for detecting electrical events that occur in the atrium of a heart; means for detecting electrical events that occur in the ventricle of the heart; means for selecting an atrial refractory period; means for timing said atrial refractory period from detected electrical events of the ventricle; means for pacing the ventricle of the heart in synchronism with atrial events detected outside said atrial refractory period; means for selecting a value of a ventricular rate limit that defines the maximum rate at which the ventricle can be paced; said means for pacing the ventricle including means for pacing the ventricle at a rate that does not exceed said value of the ventricular rate limit; means for selecting a VA time period when the ventricle is paced at a rate less than the ventricular rate limit; means for increasing the VA time period by a predefined amount when the ventricle is paced at said ventricular rate limit; means for timing the VA time period from detected ventricular events; and means for pacing the atrium at the end of said VA time period if an atrial event is not detected within said VA time period.
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37. A heart pacemaker, comprising:
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means for detecting electrical events that occur in the atrium of a heart; means for detecting electrical events that occur in the ventricle of the heart; means for selecting an atrial refractory period; means for timing said atrial refractory period from detected electrical events of the ventricle; means for pacing the ventricle of the heart in synchronism with atrial events detected outside said atrial refractory period; means for selecting a value of a ventricular rate limit that defines the maximum rate at which the ventricle can be paced; said means for pacing the ventricle including means for pacing the ventricle at a rate that does not exceed said value of the ventricular rate limit; means for counting a preselected number of successive atrial synchronous paces of the ventricle at the ventricular rate limit; means for preventing a pace of the ventricle in response to an atrial event detected outside said atrial refractory period and after said preselected number of successive atrial synchronous paces of the ventricle is counted; means for selecting a VA time period when the ventricle is paced at a rate less than the ventricular rate limit; means for increasing the VA time period by a predefined amount when the ventricle is paced at said ventricular rate limit; means for timing the VA time period from detected ventricular events; and means for pacing the atrium at the end of said VA time period if an atrial event is not detected within said VA time period.
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38. A method for operating a heart pacemaker, comprising the steps of:
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sensing electrical events in the atrium of a heart; selecting a blanking period; selecting an artifact sensing period; successively timing said blanking period and artifact sensing period after sensing an electrical event in the atrium; sensing electrical events in the ventricle of the heart during said artifact sensing period; and pacing the ventricle at a predefined time after the end of said artifact sensing period if at least one event is sensed in the ventricle during the artifact sensing period.
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Specification