Search

EP-4735104-A1 - ATRIOVENTRICULAR NODAL STIMULATION DEVICE FOR VENTRICULAR RATE CONTROL

EP4735104A1EP 4735104 A1EP4735104 A1EP 4735104A1EP-4735104-A1

Abstract

A medical device is configured to deliver an atrioventricular nodal stimulation (AVNS) therapy for suppressing atrioventricular node conduction by generating pulse trains according to AVNS control parameters. The medical device may deliver ventricular pacing pulses and determine that a threshold number of ventricular pacing pulses are delivered while the AVNS therapy is being delivered. The medical device may adjust at least one AVNS control parameter in response to determining that the threshold number of ventricular pacing pulses have been delivered.

Inventors

  • MATTSON, Alexander R.
  • DEMMER, WADE M.
  • KORNET, LILIAN
  • YANG, ZHONGPING
  • HOFFMAN, MATTHEW J.

Assignees

  • Medtronic, Inc.

Dates

Publication Date
20260506
Application Date
20240610

Claims (16)

  1. 1. A medical device system comprising: therapy delivery circuitry configured to: deliver an atrioventricular nodal stimulation (AVNS) therapy for suppressing atrioventricular node conduction by generating pulse trains according to AVNS control parameters; and generate ventricular pacing pulses; and control circuitry configured to: determine that a first threshold number of ventricular pacing pulses are delivered by the therapy delivery circuitry while the therapy delivery circuitry is delivering the AVNS therapy; and adjust at least one AVNS control parameter in response to determining that the first threshold number of ventricular pacing pulses have been delivered.
  2. 2. The medical device system of claim 1 further comprising: sensing circuitry configured to sense ventricular event signals; wherein the control circuitry is further configured to: determine ventricular event intervals from the sensed ventricular event signals and the ventricular pacing pulses delivered by the therapy delivery circuitry during the AVNS therapy; determine that the ventricular event intervals do not meet ventricular interval stability criteria; and determine that a second threshold number of ventricular pacing pulses are delivered by the therapy delivery circuitry while the therapy delivery circuitry is delivering the AVNS therapy, the second threshold number less than the first threshold number; and adjust at least one AVNS control parameter in response to determining that the second threshold number of ventricular pacing pulses have been delivered and the ventricular interval stability criteria are not met.
  3. 3. The medical device system of any one of claims 1 or 2 further comprising: sensing circuitry configured to sense cardiac event signals attendant to intrinsic depolarizations; wherein the control circuitry is further configured to: detect an atrial tachyarrhythmia based on at least the sensed cardiac event signals; determine that the sensed cardiac event signals meet unstable ventricular rate criteria; and control the therapy delivery circuitry to start delivering the AVNS therapy in response to detecting the atrial tachyarrhythmia and the sensed cardiac event signals meeting unstable ventricular rate criteria.
  4. 4. The medical device system of claim 3 wherein the control circuitry is further configured to: determine ventricular sensed event intervals from the sensed cardiac event signals; compare the ventricular sensed event intervals to a short interval threshold; determine that a threshold number of the ventricular sensed event intervals are less than the short interval threshold; and determine that the sensed cardiac event signals meet unstable ventricular rate criteria based on at least the threshold number of the ventricular sensed event intervals being less than the short interval threshold.
  5. 5. The medical device of any one of claims 3 - 4 wherein the control circuitry is further configured to: determine ventricular sensed event intervals from the sensed cardiac event signals; determine a variability metric from the ventricular sensed event intervals; determine that the variability metric meets a variability threshold; and determine that the sensed cardiac event signals meet unstable ventricular rate criteria based on at least the variability metric meeting the variability threshold.
  6. 6. The medical device system of any of one of claims 1 - 5 further comprising: sensing circuitry configured to sense cardiac event signals by sensing ventricular event signals; wherein the control circuitry is further configured to: determine that a threshold time interval of delivering the AVNS therapy by the therapy delivery circuitry without adjustment of an AVNS control parameter has expired; in response to the threshold time interval expiring, adjust at least one AVNS control parameter from a first value to a second value associated with reduced suppression of atrioventricular conduction; control the therapy delivery circuitry to deliver the AVNS therapy according to the second value of the at least one AVNS control parameter; determine sensed ventricular event intervals from the ventricular event signals sensed during the AVNS therapy delivered according to the second value; determine if stability criteria are met based on the determined sensed ventricular event intervals; restore the at least one AVNS control parameter to the first value in response to the stability criteria not being met; and control the therapy delivery circuitry to continue delivering the AVNS therapy according to the second value in response to the stability criteria being met.
  7. 7. The medical device system of any one of claims 1 - 6 further comprising: sensing circuitry configured to sense cardiac event signals attendant to intrinsic depolarizations by sensing atrial event signals and ventricular event signals; wherein the control circuitry is further configured to: determine at least one RP interval from a sensed ventricular event signal to a sensed atrial event signal; determine that the RP interval is less than a threshold interval; and in response to the at least one RP interval being less than the threshold interval, disable or adjust the AVNS therapy.
  8. 8. The medical device system of any one of claims 1 - 7 wherein the control circuitry is further configured to: detect a lead or electrode issue; and adjust or disable delivery of the AVNS therapy by the therapy delivery circuitry in response to detecting the lead or electrode issue.
  9. 9. The medical device system of any one of claims 1 - 8 wherein the control circuitry is further configured to adjust the at least one AVNS control parameter by adjusting at least one of: a pulse amplitude; a pulse width; a pulse frequency; a pulse train duration; a pulse train rate; an inter-train interval; a duty cycle; or an AVNS electrode vector.
  10. 10. The medical device system of any one of claims 1 - 9 further comprising sensing circuitry configured to sense cardiac event signals attendant to intrinsic cardiac depolarizations by sensing atrial event signals and ventricular event signals; wherein the therapy delivery circuitry is further configured to deliver the AVNS therapy by generating a pulse train according to the AVNS control parameters on every nth ventricular event signal sensed by the sensing circuitry.
  11. 11. The medical device system of any one of claims 1 - 10 further comprising sensing circuitry configured to sense cardiac event signals attendant to intrinsic cardiac depolarizations by sensing atrial event signals and ventricular event signals; wherein the therapy delivery circuitry is further configured to deliver the AVNS therapy by: starting a pulse train of the AVNS therapy in response to a sensed cardiac event signal; and terminating the pulse train of the AVNS therapy after n atrial event signals are sensed by the sensing circuitry.
  12. 12. The medical device system of any one of claims 1 - 11 further comprising sensing circuitry configured to sense cardiac event signals attendant to intrinsic cardiac depolarizations by sensing ventricular event signals; wherein the therapy delivery circuitry is further configured to deliver the AVNS therapy by: delivering a first pulse train having a pulse train duration; waiting for the sensing circuitry to sense a ventricular event signal after the pulse train duration of the first pulse train; and delivering a second pulse train after the ventricular event signal is sensed by the sensing circuitry, the second pulse train having the pulse train duration.
  13. 13. The medical device system of any one of claims 1 - 12 further comprising sensing circuitry configured to sense cardiac event signals attendant to intrinsic cardiac depolarizations; wherein the therapy delivery circuitry is further configured to deliver the AVNS therapy by: delivering a first pulse train; waiting for a minimum rate interval to expire after the first pulse train; waiting for a cardiac event signal to be sensed by the sensing circuitry after the minimum rate interval expires; and delivering a second pulse train in response to the cardiac event signal sensed by the sensing circuitry after the minimum rate interval expires.
  14. 14. The medical device system of any one of claims 1-13 further comprising: a first implantable medical device comprising: a first therapy delivery circuit of the therapy delivery circuitry, the first therapy delivery circuit being configured to deliver the AVNS therapy; and a first communication circuit; a second implantable medical device comprising: a second therapy delivery circuit of the therapy delivery circuitry, the second therapy delivery circuit being configured to generate the ventricular pacing pulses; and a second communication circuit configured to transmit a communication signal to the first communication circuit in response to at least one ventricular pacing pulse being delivered by the second therapy delivery circuit; wherein the control circuitry is further configured to determine that the threshold number of ventricular pacing pulses are delivered based on the transmitted communication signal.
  15. 15. The medical device system of any one of claims 1 - 14 further comprising sensing circuitry configured to sense ventricular event signals, wherein the control circuitry is further configured to: determine ventricular event intervals from ventricular event signals sensed by the sensing circuitry; and adjust one or more of the AVNS control parameters until the determined ventricular event intervals meet at least one of a target rate or stability criteria.
  16. 16. The medical device system of any one of claims 1 — 15 further comprising: a plurality of electrodes; and sensing circuitry configured to: sense atrial event signals attendant to atrial depolarizations; and sense ventricular event signals attendant to ventricular depolarizations; and wherein: the control circuitry is further configured to, for each of a plurality of test AVNS electrode vectors selected from the plurality of electrodes: control the therapy delivery circuitry to deliver at least one AVNS pulse train; and determine an atrioventricular conduction time interval from an atrial event signal to a ventricular event signal sensed by the sensing circuitry after the at least one AVNS pulse train is started; and select an AVNS therapy delivery electrode vector from the plurality of test AVNS electrode vectors based on the determined atrioventricular conduction time intervals; and the therapy delivery circuitry is further configured to deliver the AVNS therapy via the selected AVNS therapy delivery electrode vector.

Description

ATRIOVENTRICULAR NODAL STIMULATION DEVICE FOR VENTRICULAR RATE CONTROL [0001] This application claims the benefit of U.S. Provisional Patent Application, Serial No. 63/511,636, filed June 30, 2023, and U.S. Provisional Patent Application, Serial No. 63/625,269, filed January 25, 2024, the entire contents of each are incorporated herein by reference. TECHNICAL FIELD [0002] The disclosure relates generally to a medical device and method for delivering atrioventricular nodal stimulation (AVNS) for controlling the ventricular rate. BACKGROUND [0003] Medical devices may sense electrophysiological signals from the heart, brain, nerve, muscle or other tissue. Such devices may be implantable, wearable or external devices using implantable and/or surface (skin) electrodes for sensing the electrophysiological signals. In some cases, such devices may be configured to deliver a therapy based on the sensed electrophysiological signals. For example, implantable or external cardiac pacemakers, cardioverter defibrillators, cardiac monitors and the like, sense cardiac electrical signals from a patient’s heart. The medical device may sense cardiac electrical signals from the heart and deliver electrical stimulation therapies, such as cardiac pacing pulses and/or cardioversion or defibrillation (CV/DF) shocks, to the heart using electrodes, which may be carried by medical electrical leads extending from the medical device to position electrodes within or near the patient’s heart. [0004] A cardiac pacemaker or cardioverter defibrillator may deliver therapeutic electrical stimulation to the heart via electrodes carried by one or more medical electrical leads coupled to the medical device. Cardiac signals sensed from the heart may be analyzed for detecting an abnormal rhythm. Upon detection of an abnormal rhythm, such as bradycardia, tachycardia or fibrillation, an appropriate electrical stimulation pulse or pulses may be delivered to restore or maintain a more normal rhythm of the heart. For example, an implantable cardioverter defibrillator (ICD) may deliver bradycardia pacing pulses to the heart of the patient in the absence of sensed intrinsic myocardial depolarization signals, e.g., R-waves, deliver anti-tachycardia pacing pulses in response to detecting tachycardia, or deliver CV/DF shocks to the heart upon detecting tachycardia or fibrillation. [0005] In patients having intact intrinsic atrioventricular (AV) conduction, atrial depolarizations occurring during an atrial tachyarrhythmia such as atrial flutter or atrial fibrillation, can be conducted at to the ventricles at a fast and/or irregular rate, which can be symptomatic. Some patients experience chronic or persistent atrial fibrillation (AF) that can result a rapid and/or irregular ventricular rate. Patients diagnosed with chronic or persistent AF may undergo AV nodal ablation with implantation of a pacemaker to provide ventricular pacing. The AV nodal ablation can cause permanent AV conduction block to prevent the AF depolarizations from conducting to the ventricles. The pacemaker can provide ventricular pacing to sustain the heartbeat after AV nodal ablation, which causes the patient to become pacemaker dependent. SUMMARY [0006] In general, the disclosure is directed to a medical device and techniques for controlling and delivering AVNS therapy. The medical device may be configured to sense cardiac electrical signals and deliver AVNS and cardiac pacing as needed for promoting a regular ventricular rhythm. AVNS therapy is delivered by delivering trains of pulses to lengthen the refractory period of the AV node. AVNS may be delivered when a fast and/or irregular ventricular rate is detected to promote a regular ventricular rate. The AVNS therapy may be delivered in the area of the AV node, along a parasympathetic nerve branch or any operative location that effectively suppresses intrinsic AV conduction by the AVNS pulse trains, e.g., by lengthening the refractory period of the AV node. The AVNS pulse trains can be delivered at a pulse train frequency, amplitude and rate and according to other AVNS control parameters to block conduction of some atrial depolarizations to the ventricles but allow some atrial depolarizations to be conducted to the ventricles to promote a controlled rate of ventricular depolarizations during atrial tachyarrhythmia. When the AVNS over-inhibits or over-suppresses intrinsic AV conduction, the medical device may deliver a ventricular pacing pulse to avoid ventricular asystole. [0007] A medical device system operating according to techniques disclosed herein delivers AVNS, delivers ventricular pacing pulses in the absence of a conducted ventricular depolarization during a ventricular pacing escape interval during the AVNS, and may adjust AVNS control parameters in response to a threshold number of ventricular pacing pulses being delivered during the delivered AVNS therapy. The AVNS control parameters may be adjusted to promote intrinsic AV