US 5,514,164 A · DDD pacing response to atrial tachyucardia and retrograde conduction

Abstract

An implantable pacemaker operates in a DDD mode and reverts to a modified DDI mode in response to sensing atrial depolarization early in the pacing cycle. The modified DDI mode, when invoked, provides additional atrial kick by generating an atrial stimulation pulse (A-pulse) when there is sufficient time left in the current pacing cycle for the atrial kick resulting from such A-pulse to be of hemodynamic and electrophysiologic benefit. A time window, T.sub.A, is defined that follows the post-ventricular atrial refractory period (PVARP) of the normal DDD pacing cycle. If a P-wave is sensed during T.sub.A, then the modified DDI mode is invoked. In such modified DDI mode, the time between the last ventricular event and the next scheduled V-pulse, absent the detection of an inhibiting R-wave, is preserved. Further, in such modified DDI mode, if there is sufficient time to supply an A-pulse before the next V-pulse is scheduled, such A-pulse will be generated to provide the additional atrial kick. In one embodiment, if there is more than a fixed time interval e.g., 300 msec, plus a programmed AV delay (AVD) time remaining before the next scheduled V-pulse after sensing a P-wave during the time window T.sub.A, then an A-pulse is generated one AVD time prior to the next scheduled V-pulse.

Claims47

Dependent claims

A dual-chamber DDD pacemaker for stimulating the heart of a patient, said pacemaker comprising:

ventricular pulse generating means for generating and delivering a ventricular stimulation pulse (V-pulse) to a ventricle of the patient's heart in response to a ventricular control signal;
atrial pulse generating means for generating and delivering an atrial stimulation pulse (A-pulse) to an atrium of the patient's heart in response to an atrial control signal;
sensing means for sensing natural depolarizations of the patient's heart and generating a P-wave signal in response to sensing an atrial depolarization and an R-wave signal in response to sensing a ventricular depolarization;
and
control means responsive to said P-wave signal and R-wave signal for defining a pacing cycle and selectively generating said atrial control signal and said ventricular control signal within said pacing cycle based on the amount of time between said P-wave signal and R-wave signal, said control means including assurance means for assuring that the atrial control signal occurs at a time within the pacing cycle such that the resulting A-pulse is effective at stimulating the atrium of the patient's heart, wherein said assurance means within said control means comprises means for generating an atrial control signal within the pacing cycle, and hence an A-pulse, following a P-wave signal of the pacing cycle only when there is more than a prescribed time period T.sub.P remaining within the pacing cycle after the P-wave signal before the next atrial control signal is scheduled to be generated by said control means.

2 more elements

A DDD pacemaker for stimulating the heart of a patient, said pacemaker comprising:

stimulation means for generating and delivering a ventricular stimulation pulse (V-pulse) to a ventricle of the patient's heart in response to a V-pulse trigger signal, and means for generating and delivering an atrial stimulation pulse (A-pulse) to an atrium of the patient's heart in response to an A-pulse trigger signal;
sensing means for sensing natural depolarizations of the patient's heart and generating a P-wave signal in response to a sensed atrial depolarization and an R-wave signal in response to a sensed ventricular depolarization;
and
control means responsive to said P-wave signal and R-wave signal for defining a pacing cycle and generating said atrial trigger signal within said pacing cycle only when said P-wave signal does not occur within a first specified time period within said pacing cycle, and for inhibiting the generation of said atrial trigger signal within said pacing cycle whenever said P-wave signal does occur within the first specified time period of said pacing cycle, whereby said control means defines the pacing cycle to track appropriate atrial depolarizations, said control means further including prevention means for preventing said control means from defining a pacing cycle that tracks inappropriate atrial depolarizations associated with retrograde conduction, atrial flutter, and atrial fibrillation.

1 more element

A dual-chamber implantable pacemaker adapted to operate in a modified DDD mode, the pacemaker comprising:

a battery, electronic pacing circuitry powered by the battery, and an output connector electrically connected to the electronic pacing circuitry, the output connector being adapted to be electrically coupled through an atrial lead and electrode to an atrium of a patient's heart, and through a ventricular lead and electrode to a ventricle of the patient's heart, the electronic pacing circuitry including:
an atrial channel coupled to the output connector, including means for generating an atrial stimulation pulse (A-pulse) that is delivered through the atrial lead and electrode to the atrium of the patient's heart, and means for sensing an atrial depolarization signal (P-wave) through the atrial lead and electrode;
a ventricular channel coupled to the output connector, including means for generating a ventricular stimulation pulse (V-pulse) that is delivered through the ventricular lead and electrode to the ventricle of the patient's heart, and means for sensing a ventricular depolarization signal (R-wave) through the ventricular lead and electrode;
timing means for generating a plurality of timing intervals, including a post-ventricular atrial refractory period (PVARP), an atrial escape interval (AEI), an AV delay (AVD), a T.sub.A interval, and a T.sub.P interval, and where the combined duration of the AEI followed by the AVD comprise the period of a pacing cycle;
and
control means for controlling the operation of the atrial channel, ventricular channel, and timing means so as to control the pacemaker to operate in the modified DDD mode of operation, the modified DDD mode of operation including:
first means for simultaneously starting the PVARP and the AEI upon the occurrence of a ventricular event, where a ventricular event comprises either the generating of a V-pulse or the sensing of an R-wave within the ventricular channel;
second means for commencing the AVD upon either the timing-out or resetting of the AEI, whichever occurs first;
third means for commencing the T.sub.A interval at the conclusion of the PVARP;
fourth means for commencing the T.sub.P interval whenever a P-wave is sensed during the T.sub.A interval;
fifth means for determining if the T.sub.P interval has timed out when the AEI times-out, and if so generating an A-pulse;
and
sixth means for generating a V-pulse at the timing-out of the AVD, and for inhibiting such V-pulse in the event an R-wave is sensed before the timing-out of the AVD;
whereby, if a P-wave is sensed to have occurred during the T.sub.A interval, an A-pulse is generated in the atrial channel at the timing-out of the AEI if a time period of at least T.sub.P has elapsed since a most recent P-wave was sensed, said time period T.sub.P having a duration that is at least as long as a natural refractory period of the patient's heart following a P-wave.

11 more elements

A dual-chamber implantable pacemaker comprising:

an atrial channel including means for sensing a P-wave and means for generating an A-pulse;
a ventricular channel including means for sensing an R-wave and means for generating a V-pulse;
a control system coupled to the atrial and ventricular channels for controlling the operation of the atrial and ventricular channels in accordance with an improved DDD mode of operation;
a memory coupled to the control system having sufficient memory capacity for storing a set of control parameters that define the improved DDD mode of operation;
said control system including:
programmable timing means for defining a set of time intervals as a function of the set of control parameters, said set of time intervals including a post-ventricular atrial refractory period (PVARP), an atrial escape interval (AEI), an AV delay (AVD), and a T.sub.A interval;
and
logic circuitry responsive to the state of the programmable timing means and to the sensed occurrence of P-waves and R-waves for generating a set of control signals that control the operation of the pacemaker to conform its operation with the improved DDD mode, said logic circuitry including means for:
defining a pacing cycle that begins upon the occurrence of a ventricular event and terminates upon the occurrence of a successive ventricular event, where a ventricular event comprises either the sensing of an R-wave or the generating of a V-pulse,
starting the AEI and the PVARP at the beginning of each pacing cycle,
starting the T.sub.A interval at the conclusion of the PVARP,
sensing whether a P-wave occurs during the T.sub.A interval, and if so, determining whether sufficient time remains within the pacing cycle for an A-pulse to be generated at a time within the pacing cycle that such A-pulse will be effective, and if so, generating such A-pulse at a specified time within the pacing cycle,
if a P-wave does not occur during the T.sub.A interval, sensing whether a P-wave occurs after the T.sub.A interval but before the termination of the AEI, and if so, immediately resetting the AEI, and
starting the AVD upon the timing-out of the AEI if a P-wave is sensed during the T.sub.A interval, or upon the resetting of the AEI if a P-wave is sensed after the T.sub.A interval, with the AVD terminating upon the earliest occurrence of either the sensing of an R-wave or the timing-out of the AVD.

11 more elements

A dual-chamber implantable pacemaker comprising:

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 an atrial stimulation pulse (A-pulse) and a ventricular stimulation pulse (V-pulse);
control means for controlling the sensing means and pulse generating means so as to operate the pacemaker in a modified DDD mode of operation, the modified DDD mode of operation being characterized by a pacing period, defined by a sequence that comprises an atrial escape interval (AEI) followed by an AV delay (AVD), and by a post-ventricular atrial refractory period (PVARP) that commences at the beginning of each pacing period concurrent with the AEI, and by an interval T.sub.A that begins upon the termination of the PVARP;
said control means including means for reverting to a modified DDI mode of operation for the duration of the pacing period in the event a P-wave is sensed by the sensing means during the interval T.sub.A.

1 more element

A method of operating a dual-chamber implantable pacemaker comprising:

(a) sensing when an atrial depolarization (P-wave) and a ventricular depolarization (R-wave) occur within a patient's cardiac cycle;
(b) generating an atrial stimulation pulse (A-pulse) and a ventricular stimulation pulse (V-pulse) in accordance with a modified DDD mode of operation, a DDD mode of operation being characterized by generating an atrial escape interval (AEI) and an AV delay (AVD), with the AEI and AVD each being of a preset maximum duration, and by defining a pacing period as the AEI followed by the AVD, and generating an A-pulse at the conclusion of the AEI only if a P-wave is not sensed during the AEI, and terminating the AEI immediately upon sensing a P-wave, and generating a V-pulse at the conclusion of the AVD only if a depolarization is not sensed before the timing-out of the AVD, and terminating the AVD immediately upon sensing an R-wave, thus ending the pacing period and beginning the next pacing period;
and
(c) modifying the DDD operation of step (b) by reverting to a modified DDI mode of operation in the event a P-wave is sensed within a predetermined time window within the pacing period, said modified DDI mode being effectuated by:
(1) preserving the time between the last ventricular event and the next scheduled V-pulse, absent the sensing of an R-wave, and
(2) generating an A-pulse if there remains sufficient time within the pacing period for such A-pulse to be generated at least a prescribed time interval after the sensing of a P-wave and at least a second prescribed time interval, X, prior to the next scheduled V-pulse.

3 more elements

A method of operating an implantable dual-chamber pacemaker in a modified DDD mode of operation;

the dual-chamber pacemaker including an atrial channel having A-pulse generating means and P-wave sensing means;
a ventricular channel having V-pulse generating means and R-wave sensing means;
control means for controlling the operation of the atrial and ventricular channel in accordance with a prescribed mode of operation, the control means including a plurality of timers that define a plurality of time intervals;
and means for programming the control means to operate in accordance with the prescribed mode of operation;
the method comprising the steps of:
(a) monitoring the ventricular channel for the occurrence of a ventricular event, the ventricular event comprising either the sensing of an R-wave or the generating of a V-pulse;
(b) commencing the timing-out of a post-ventricular atrial refractory period (PVARP), and an atrial escape interval (AEI) upon sensing a ventricular event in step (a);
(c) starting the timing-out of a predetermined interval T.sub.A at the conclusion of the PVARP;
(d) monitoring the atrial channel during the timing-out of the interval T.sub.A for the occurrence of a P-wave;
(e) in the event a P-wave is sensed during the monitoring of step (d), starting the timing-out of an interval T.sub.P, waiting for the AEI to time-out, and determining if the interval T.sub.P has timed out at the timing-out of the AEI;
(f) in the event the interval T.sub.P has timed out at the timing-out of the AEI, generating an A-pulse, and starting the timing-out of an AV delay (AVD);
(g) in the event the interval T.sub.P has not timed out at the timing-out of the AEI in step (e), inhibiting the generation of an A-pulse, and starting the timing-out of the AVD;
(h) in the event a P-wave is not sensed during the monitoring of step (d), but is sensed after the timing-out of the interval T.sub.A and before the timing-out of the AEI, immediately resetting the AEI, inhibiting the generation of an A-pulse at the conclusion of the reset AEI, and starting the timing-out of the AVD;
(i) monitoring the ventricular channel at least during the timing-out of the AVD, and generating a V-pulse if no R-wave is sensed before the timing-out of the AVD;
(j) commencing the timing-out of the PVARP and the AEI upon the occurrence of a ventricular event in step (i), where a ventricular event comprises either the generating of a V-pulse or the sensing of an R-wave;
and
(k) repeating steps (c)-(j) for so long as the pacemaker is operated in the modified DDD mode of operation.

14 more elements

Dependencies are inferred from the claim text.

DDD pacing response to atrial tachyucardia and retrograde conduction

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DDD pacing response to atrial tachyucardia and retrograde conduction

Life of this patent

Abstract

Claims47