Pacemaker having PVC response and PMT terminating features
First Claim
1. A method of operating a dual-chamber cardiac pacemaker, said dual-chamber cardiac pacemaker including means for sensing a premature ventricular contraction (PVC), comprising the steps of:
- (a) generating an extended atrial refractory period upon the sensing of a PVC, said extended atrial refractory period comprising a first prescribed time period during which electrical activity in the atrium of a heart being paced by said pacemaker is not sensed by said pacemaker;
(b) generating an atrial alert time interval that is initiated at the conclusion of the extended atrial refractory period, said atrial alert time interval comprising a second prescribed time period during which electrical activity in the atrium is sensed, but during which no pacemaker-generated stimulation pulses are delivered to the atrium;
(c) delivering a pacemaker-generated stimulation pulse to the atrium at the conclusion of the atrial alert time interval only when no electrical activity is sensed in the atrium during the atrial alert time interval; and
(d) generating an A-V time interval that is initiated at the conclusion of the atrial alert time interval, said A-V time interval comprising a third time period at the conclusion of which a ventricular stimulation pulse may be selectively delivered to the ventricle of the heart by said pacemaker.
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Accused Products
Abstract
An atrial tracking dual-chamber pacemaker and method of use for reducing the risk of initiating a pacer mediated tachycardia (PMT), and breaking such a PMT if once started. The pacemaker includes means for sensing a premature ventricular contraction (PVC). The pacemaker operates in a conventional manner unless a PVC is sensed. If a PVC is sensed, in accordance with one embodiment, an extended atrial refractory period is triggered in an attempt to block any retrograde atrial events resulting from the PVC. This is followed by an atrial alert time window. After a prescribed A-V delay subsequent to the timing out or other termination of the atrial alert time window, a ventricular stimulation pulse is generated, unless prior ventricular activity is sensed that inhibits such ventricular stimulation pulse. In accordance with another embodiment, the sensing of a PVC triggers, after a suitable refractory period, a retrograde sense period during which any sensed atrial electrical activity is presumed to be a retrograde event. Appropriate steps are taken in order to deal with the retrograde event to prevent its occurrence from triggering a PMT. If a PMT has started, a prescribed number of cycles of the PMT are counted, after which the same action used in response to a sensed PVC is triggered, which action disrupts the rhythm of the PMT so as to break it. If the PMT is not broken with the first attempt, the PVC response is recurringly generated after a prescribed number of subsequent PMT cycles.
425 Citations
56 Claims
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1. A method of operating a dual-chamber cardiac pacemaker, said dual-chamber cardiac pacemaker including means for sensing a premature ventricular contraction (PVC), comprising the steps of:
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(a) generating an extended atrial refractory period upon the sensing of a PVC, said extended atrial refractory period comprising a first prescribed time period during which electrical activity in the atrium of a heart being paced by said pacemaker is not sensed by said pacemaker; (b) generating an atrial alert time interval that is initiated at the conclusion of the extended atrial refractory period, said atrial alert time interval comprising a second prescribed time period during which electrical activity in the atrium is sensed, but during which no pacemaker-generated stimulation pulses are delivered to the atrium; (c) delivering a pacemaker-generated stimulation pulse to the atrium at the conclusion of the atrial alert time interval only when no electrical activity is sensed in the atrium during the atrial alert time interval; and (d) generating an A-V time interval that is initiated at the conclusion of the atrial alert time interval, said A-V time interval comprising a third time period at the conclusion of which a ventricular stimulation pulse may be selectively delivered to the ventricle of the heart by said pacemaker. - View Dependent Claims (2, 3)
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4. A method of operating a dual-chamber pacemaker, said dual-chamber cardiac pacemaker including means for sensing a premature ventricular contraction (PVC), comprising the steps of:
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(a) generating a first time period that begins upon the sensing of a PVC; (b) generating a second time period that is initiated upon the occurrence of a first prescribed event occurring within said first time period; (c) delivering an atrial stimulation pulse to the atrium of a heart being paced by said pacemaker at the conclusion of the second time period, unless a second prescribed event occurs during said second time period, in which case no atrial stimulation pulse is generated; (d) generating a third time period that is initiated at the conclusion of the second time period; and (e) delivering a ventricular stimulating pulse to the ventricle of the heart at the conclusion of the third time period providing a third prescribed event has previously occurred. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operating a dual-chamber pacemaker, said pacemaker including means for sensing atrial and ventricular activity, as well as means for sensing a premature ventricular contraction (PVC), comprising the steps of:
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(a) generating, in response to sensing, ventricular activity, an atrial escape interval and a maximum tracking interval, at least a latter portion of said atrial escape interval comprising a time period during which atrial activity is sensed, an A-V interval being generated at the earliest occurrence of either;
(1) the sensing of atrial activity within the latter portion of said atrial escape interval or (2) the conclusion of said actual escape interval, said maximum tracking interval plus said A-V interval comprising a time period that defines a maximum pacing rate of said pacemaker;(b) suspending said atrial escape interval and said maximum tracking interval in response to the sensing of atrial activity within the latter portion of said atrial escape interval that occurs subsequent to the sensing of a PVC; (c) generating, in response to the sensing of atrial activity, said A-V interval; and (d) generating a ventricular stimulating pulse at the conclusion of said A-V interval. - View Dependent Claims (15)
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16. A method of breaking a pacer mediated tachycardia (PMT) in a dual-chamber cardiac pacemaker, said dual-chamber cardiac pacemaker including sensing means for selectively sensing electrical activity in a ventricle and an atrium of a heart, and pacing means for selectively delivering stimulation pulses to at least the ventricle in accordance with a prescribed timing sequence, said method of breaking a PMT comprising the steps of:
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(a) counting a prescribed number of PMT cycles; and (b) extending the time at which said pacing means delivers one of said stimulation pulses to the ventricle in the next PMT cycle, thereby changing the V--V interval of this next PMT cycle. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. In a pacemaker having means for detecting the occurrence of a premature ventricular contraction (PVC), and means for sensing first and second cardiac events associated with the operation of said pacemaker, a system for responding to a PVC comprising:
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means for generating a first time period that begins upon the sensing of a PVC by said PVC detection means; means for generating a second time period that is initiated upon the occurrence of said first prescribed cardiac event occurring during said first period; means for generating a third time period that is initiated upon the occurrence of said second prescribed cardiac event; and delivery means for selectively delivering a stimulation pulse to a ventricle of a heart being paced by said pacemaker at the end of said third time period. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. A cardiac pacemaker including
atrail and ventricular sensing means for respectively sensing atrial and ventricular depolarizations of a heart; -
pulse generating means for generating stimulation pulses that may be selectively delivered to the ventricle in response to a ventricular trigger signal; timing means for generating said ventricular trigger signal in response to a prescribed timing sequence, said timing means including inhibiting means responsive to said ventricular sensing means for inhibiting said ventricular trigger signal in response to sensed ventricular depolarizations, premature ventricular contraction (PVC) means for sensing a premature ventricular contraction, said premature ventricular contraction comprising a ventricular depolarization that occurs subsequent to a prior ventricular depolarization and prior to an atrial depolarization or the timing out of an atrial escape interval, whichever occurs first, and for generating a PVC signal in response to the sensing of a PVC, means for generating an extended atrial refractory period in response to said PVC signal, said extended atrial refractory period comprising a period of time during which the atrial sensing means of said pacemaker is not operable, means for generating an atrial alert time window subsequent to the timing to of said extended atrial refractory period, said atrial alert time window comprising a prescribed period of time during which the atrial sensing means is operable, and means for generating an A-V interval that begins at the conclusion of said atrial alert time window, said A-V interval comprising a prescribed period of time during which the ventricular sensing means is operable, said ventricular trigger signal being generated at the conclusion of said A-V interval unless said ventricular trigger signal is inhibited by said inhibiting means. - View Dependent Claims (34, 35, 36, 37, 38, 39)
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40. A cardiac pacemaker including
atrial and ventricular sensing means for respectively sensing atrial and ventricular depolarizations of a heart; -
pulse generating means for generating stimulation pulses that may be selectively delivered to the ventricle in response to a ventricular trigger signal; timing means for generating said ventricular trigger signal in response to a prescribed timing sequence, said timing means including inhibiting means responsive to said ventricular sensing means for inhibiting said ventricular trigger signal in response to sensed ventricular depolarizations, premature ventricular contraction (PVC) means for sensing a premature ventricular depolarization contraction, said premature ventricular contraction comprising a ventricular depolarization that occurs subsequent to a prior ventricular depolarization and prior to an atrial depolarization or the timing out of an atrial escape interval, whichever occurs first, and for generating a PVC signal in response to the sensing of a PVC, means for generating and atrial refractory period in response to said PVC signal, said atrial refractory period comprising a prescribed period of time during which the atrial sensing means of said pacemaker is not operable, means for generating a retrograde sense period subsequent to said atrial refractory period during which the atrial sensing means is operable, means for generating an atrial escape interval that begins in response to said PVC signal, said atrial escape interval comprising an AEI time period that is at least as long as the duration of the atrial refractory period followed by the retrograde sense period, means for generating an atrial alert time window of a first prescribed time period that beings in response to the sensing of an atrial depolarization occurring during the retrograde sense period, and means for generating an A-V interval that begins at the conclusion of said AEI time if no atrial depolarization is sensed during the retrograde sense period, or at the earliest occurrence of either the conclusion of said atrial alert time window or the sensing of an atrial depolarization by said atrial sensing means during said atrial alert time window, said A-V interval comprising a second prescribed time period during which the ventricular sensing means is operable, said ventricular trigger signal being generated at the conclusion of said A-V interval unless said ventricular trigger signal is inhibited by said inhibiting means. - View Dependent Claims (41, 42, 43, 44, 45, 46)
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47. An atrial tracking dual-chamber pacemaker comprising
atrial and ventricular sensing means for sensing electrical activity occurring in an atrium and ventricle of a heart, respectively; -
pulse generating means coupled to said atrial and ventricular sensing means for generating a ventricular trigger signal, which ventricular trigger signal causes a ventricular stimulation pulse to be generated; inhibiting means responsive to said ventricular sensing means for inhibiting said ventricular trigger signal whenever ventricular electrical activity is sensed within a first prescribed time period prior to the generation of said ventricular trigger signal; timing means for controlling the operation of said atrial and ventricular sensing means in a way that minimizes the likelihood that retrograde atrial electrical activity will trigger a pacer mediated tachycardia. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55, 56)
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Specification