Implantable pacemaker having adaptive AV interval adoptively shortened to assure ventricular pacing
First Claim
1. A dual-chamber pacemaker providing atrioventricular pacing in order to increase cardiac output in a patient suffering from a cardiomyopathy, comprising:
- an atrial channel and a ventricular channel;
an atrial sense amplifier that senses a P-wave in the atrial channel, said P-wave representing natural atrial activity;
a ventricular sense amplifier that senses an R-wave in the ventricular channel, said R-wave representing natural ventricular activity;
pulse generator means for generating an atrial stimulation pulse (A-pulse) in the atrial channel in the absence of a sensed P-wave by said atrial sense amplifier within an atrial escape interval, and a ventricular stimulation pulse (V-Pulse) in the ventricular channel in the absence of a sensed R-wave by said ventricular sense amplifier within an AV time interval;
a control system that defines said AV time interval and said atrial escape interval, said AV time interval beginning upon the sensing of a P-wave or the generation of an A-pulse, whichever event occurs first in the atrial channel, and said atrial escape interval beginning upon the sensing of an R-wave or the generation of a V-pulse, whichever event occurs first in the ventricular channel; and
timing means as part of said control system for measuring a conduction time interval as the time period between atrial activity in the atrial channel and the sensing of an R-wave in the ventricular channel, and for automatically setting said AV time interval to a value that for ventricular pacing is always less than the measured conduction time interval by a prescribed amount, said atrial activity comprising the generation of an A-pulse or the sensing of a P-wave, whichever event occurs first, in the atrial channel;
whereby, in the absence of a decreasing conduction time interval, said pulse generator means generates said V-pulse in the ventricular channel prior to the occurrence of an R-wave, thereby providing ventricular pacing for increasing cardiac output; and
furtherwhereby, in the presence of a decreasing conduction time interval, said AV time interval is automatically adjusted to a value less than the shortest conduction time interval.
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Accused Products
Abstract
A dual-chamber implantable pacemaker configured to operate in the DDD or DDDR mode automatically adjusts its AV (or PV) interval to an amount just less than the natural conduction time of a patient, thereby assuring that ventricular pacing occurs in a patient'"'"'s cardiac cycle at a time near when a natural ventricular contraction (an R-wave) would occur. The pacemaker includes a pulse generator that generates ventricular stimulation pulses (V-pulses) at the conclusion of a pacemaker-defined AV (or PV) interval if no natural ventricular activity (an R-wave) is sensed during such AV (or PV) interval. The AV (or PV) intervals are automatically adjusted by the pacemaker to be just less than the natural conduction time sensed by the pacemaker, where the natural conduction time is the time between atrial activity (a sensed P-wave or a delivered A-pulse) and the subsequent natural ventricular activity (R-wave). The system and method are particularly adapted for use by patients suffering from a cardiomyopathy in order to improve cardiac output.
115 Citations
34 Claims
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1. A dual-chamber pacemaker providing atrioventricular pacing in order to increase cardiac output in a patient suffering from a cardiomyopathy, comprising:
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an atrial channel and a ventricular channel; an atrial sense amplifier that senses a P-wave in the atrial channel, said P-wave representing natural atrial activity; a ventricular sense amplifier that senses an R-wave in the ventricular channel, said R-wave representing natural ventricular activity; pulse generator means for generating an atrial stimulation pulse (A-pulse) in the atrial channel in the absence of a sensed P-wave by said atrial sense amplifier within an atrial escape interval, and a ventricular stimulation pulse (V-Pulse) in the ventricular channel in the absence of a sensed R-wave by said ventricular sense amplifier within an AV time interval; a control system that defines said AV time interval and said atrial escape interval, said AV time interval beginning upon the sensing of a P-wave or the generation of an A-pulse, whichever event occurs first in the atrial channel, and said atrial escape interval beginning upon the sensing of an R-wave or the generation of a V-pulse, whichever event occurs first in the ventricular channel; and timing means as part of said control system for measuring a conduction time interval as the time period between atrial activity in the atrial channel and the sensing of an R-wave in the ventricular channel, and for automatically setting said AV time interval to a value that for ventricular pacing is always less than the measured conduction time interval by a prescribed amount, said atrial activity comprising the generation of an A-pulse or the sensing of a P-wave, whichever event occurs first, in the atrial channel; whereby, in the absence of a decreasing conduction time interval, said pulse generator means generates said V-pulse in the ventricular channel prior to the occurrence of an R-wave, thereby providing ventricular pacing for increasing cardiac output; and
furtherwhereby, in the presence of a decreasing conduction time interval, said AV time interval is automatically adjusted to a value less than the shortest conduction time interval. - View Dependent Claims (2, 3, 4, 5)
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6. A dual-chamber implantable pacemaker programmed to operate in a DDD or DDDR mode of operation so as to generate a ventricular stimulation pulse (V-pulse) during a given cardiac cycle prior to natural ventricular activity, yet at a time delayed sufficiently from any preceding atrial activity to assure efficient cardiac output, said pacemaker comprising:
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sensing means for sensing P-waves and R-waves; stimulation means for generating V-pulses and A-pulses; measurement means for measuring the natural conduction time, tPR, or tAR, of a heart to which the pacemaker is coupled, where tPR represents the natural conduction time following a natural atrial event (P-wave), and tAR represents the natural conduction time of the heart following an atrial stimulation pulse (A-pulse); and timing means for automatically setting a PV interval for use by said pacemaker following a P-wave, and an AV interval for use by said pacemaker following an A-pulse, to a prescribed amount less than said natural conduction time, tPR or tAR, respectively, said PV and AV intervals being used by said timing means to define the time period between a P-wave and a V-pulse, and between an A-pulse and a V-pulse, respectively, during the operation of said pacemaker. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A dual chamber pacemaker comprising:
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means for sensing and pacing in both an atrial and ventricular channel; timing means for setting an AV interval, said AV interval comprising the maximum time period allowed by the pacemaker between atrial channel activity, which atrial channel activity includes sensing or pacing in the atrial channel, and pacing in the ventricular channel; measurement means for measuring a first time interval as the time interval between atrial channel activity and sensing in the ventricular channel; adjustment means for automatically setting the AV interval of said pacemaker to a value that for pacing in the ventricular channel is always less than the most recently measured first time interval; and control means for pacing in the ventricular channel at the conclusion of said AV interval in the event that no sensing occurs in the ventricular channel during said AV interval, whereby ventricular pacing is provided. - View Dependent Claims (16, 17)
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18. A method of operating a dual-chamber implantable pacemaker to provide ventricular stimulation pulses at a time within a cardiac cycle that is just prior to when a natural ventricular contraction would occur, said implantable pacemaker including means for sensing natural atrial contractions (P-waves), means for sensing natural ventricular contractions (R-waves), means for generating atrial stimulation pulses (A-pulses), means for generating ventricular stimulation pulses (V-pulses), and timing means for defining an AV interval that commences with the generation of an A-pulse, and a PV interval that commences with the sensing of a P-wave, said method comprising:
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(a) electronically measuring a first time interval within a given cardiac cycle that comprises the time between an atrial event and an R-wave, said atrial event comprising either an A-pulse or a P-wave, whichever event occurs first in the given cardiac cycle; (b) automatically setting said AV interval to be equal to said first time interval less a first prescribed amount; (c) automatically setting said PV interval to be equal to said first time interval less a second prescribed amount; and (d) issuing a V-pulse at the conclusion of said AV interval, in the event an A-pulse has first been generated, or at the conclusion of said PV interval, in the event a P-wave has first been sensed;
whereby said V-pulse is always generated at the conclusion of said AV or PV interval following said atrial event. - View Dependent Claims (19, 20, 21, 22)
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23. In a dual-chamber implantable pacemaker programmed to operate in a DDD or DDDR mode of operation, a method of operating said pacemaker when coupled to a heart of a patient so as to generate a ventricular stimulation pulse (V-pulse) during a given cardiac cycle prior to natural ventricular activity, yet at a time delayed sufficiently from any preceding atrial activity to assure efficient cardiac output, said pacemaker including means for sensing P-waves and R-waves, and means for generating V-pulses and A-pulses, said method comprising the steps of:
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(a) determining the natural conduction time of the heart, tPR or tAR, where tPR represents the natural conduction time following a natural atrial event (P-wave), and tAR represents the natural conduction time of the heart following an atrial stimulation pulse (A-pulse); (b) automatically setting a PV interval, for use by said pacemaker following a P-wave, and an AV interval, for use by said pacemaker following an A-pulse, to a prescribed amount less than said natural conduction time, tPR or tAR, respectively; (c) performing at least one pacing cycle in said DDD or DDDR mode of operation using the PV and AV intervals to define the time period between an atrial event and the generation of a V-pulse; (d) automatically adjusting said PV and AV intervals to make them a prescribed amount less than the PV or AV interval used most recently by said pacemaker in the event an R-wave is sensed during said at least one pacing cycle; and (e) automatically adjusting said PV and AV intervals to make them a prescribed amount greater than the PV or AV interval used most recently by said pacemaker, up to a predetermined maximum PV or AV interval, in the event no R-wave is sensed for a specified number of cardiac cycles. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A method of providing ventricular pacing in order to increase cardiac output in a cardiomyopathy patient, such patient having a dual-chamber pacemaker, said pacemaker including means for sensing and pacing in both an atrial and ventricular channel, and timing means for setting an AV interval, said method comprising the steps of:
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(a) measuring a first time interval as the time interval between atrial channel activity and sensing in the ventricular channel for determining a natural conduction time, said atrial channel activity comprising sensing or pacing in the atrial channel; (b) automatically setting the AV interval of said pacemaker to a value that is a prescribed amount less than the natural conduction time, where said AV interval defines the time interval between atrial channel activity and pacing in the ventricular channel; and (c) pacing in the ventricular channel at the conclusion of said AV interval. - View Dependent Claims (31, 32)
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33. A dual-chamber pacemaker for controlling ventricular pacing in order to increase cardiac output in a patient suffering from a cardiomyopathy by preemptively stimulating the ventricular channel comprising:
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an atrial channel and a ventricular channel; an atrial sense amplifier that senses a P-wave in the atrial channel, said P-wave representing natural atrial activity; a ventricular sense amplifier that senses an R-wave in the ventricular channel, said R-wave representing natural ventricular activity; pulse generator means for generating a ventricular stimulation pulse (V-Pulse) in the ventricular channel and an atrial stimulation pulse (A-pulse) in the atrial channel, the sensing of a P-wave or the generating of an A-pulse, whichever occurs first, comprising atrial activity; and timing means for defining an AV time interval as the time interval between atrial activity and the generation of a V-pulse, said timing means further for measuring a natural conduction time interval as the time period between atrial activity and the sensing of an R-wave, and for automatically setting said AV time interval to a value that is less than said natural conduction time interval, whereby said pulse generator generates said V-pulse prior to the occurrence of natural ventricular activity for preemptively stimulating the ventricular channel to thereby increase cardiac output. - View Dependent Claims (34)
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Specification