US-20260124455-A1 - HEART RATE BASED CONTROL OF CARDIAC RESYNCHRONIZATION THERAPY

US20260124455A1US 20260124455 A1US20260124455 A1US 20260124455A1US-20260124455-A1

Abstract

In some examples, controlling delivery of cardiac resynchronization therapy (CRT) includes storing, in a memory of an implantable medical device system and in association with each of a plurality of heart rates, at least one respective value for an interval between an atrial event and a ventricular event. Processing circuitry of the implantable medical device system may determine a heart rate of a patient and select one of the stored values for the interval between the atrial event and the ventricular event associated with the determined heart rate. The processing circuitry may further determine whether to control therapy delivery circuitry of the implantable medical device system to deliver fusion pacing or biventricular pacing, based on the selected one of the stored values for the interval between the atrial event and the ventricular event.

Inventors

Nathan A. Grenz
Thomas J. Mullen

Assignees

MEDTRONIC, INC.

Dates

Publication Date: 20260507
Application Date: 20260105

Claims (20)

1 . A method for controlling delivery of pacing therapy, the method comprising: storing, in a memory of an implantable medical device system and in association with each of a plurality of heart rates, a respective value for each of a first interval between an intrinsic atrial event and a ventricular event and a second interval between a paced atrial event and the ventricular event; and by processing circuitry of the implantable medical device system: determining a heart rate of a patient; determining whether an atrial event was intrinsic or paced; selecting one of the stored values, wherein the stored values comprise the stored value for the first interval between the intrinsic atrial event and the ventricular event associated with the determined heart rate, and the stored value for the second interval between the paced atrial event and the ventricular event associated with the determined heart rate based on the determination of whether the atrial event was intrinsic or paced; comparing the selected one of the stored values to a threshold value; and controlling therapy delivery circuitry of the implantable medical device system to deliver the pacing therapy based on the comparing of the selected one of the stored values and the threshold value, wherein the pacing therapy comprises fusion pacing or biventricular pacing.
2 . The method of claim 1 , the method further comprising determining, by the processing circuitry, whether to control the therapy delivery circuitry to deliver fusion pacing or biventricular pacing based on the selected one of the stored values.
3 . The method of claim 2 , wherein determining whether to control therapy delivery circuitry of the implantable medical device system to deliver fusion pacing or biventricular pacing based on the selected one of the stored values comprises: controlling the therapy delivery circuitry of the implantable medical device system to deliver fusion pacing in response to the selected one of the stored values being less than the threshold value.
4 . The method of claim 3 , wherein the fusion pacing includes left ventricular pacing.
5 . The method of claim 1 , wherein controlling therapy delivery circuitry of the implantable medical device system to deliver the pacing therapy comprises controlling the therapy delivery circuitry of the implantable medical device system to deliver the pacing therapy for a current cardiac cycle, and wherein determining the heart rate comprises determining a length of a preceding cardiac cycle.
6 . The method of claim 2 , wherein selecting one of the stored values and determining whether to control therapy delivery circuitry of the implantable medical device system to deliver fusion pacing or biventricular pacing comprises selecting the one of the stored values and determining whether to control therapy delivery circuitry of the implantable medical device system to deliver fusion pacing or biventricular pacing for each of a plurality of consecutive cardiac cycles.
7 . The method of claim 2 , further comprising, periodically, by the processing circuitry: determining the heart rate of the patient; selecting either the stored value for the first interval or the stored value for the second interval associated with the determined heart rate; suspending the delivery of pacing therapy; while the delivery of pacing therapy is suspended, measuring a current value of the either of the first interval or the second interval; comparing the current value of the either of the first interval or the second interval to the selected value of the either of the first interval or the second interval; and updating at least the selected value of the either of the first interval or the second interval associated with the determined heart rate in the memory based on the comparison.
8 . The method of claim 1 , wherein the respective value for the first interval comprises: a first value for the first interval associated with a waking state of the patient; and a second value for the first interval associated with a sleeping state of the patient, and wherein the respective value for the second interval comprises: a first value for the second interval associated with the waking state of the patient; and a second value for the second interval associated with the sleeping state of the patient.
9 . The method of claim 1 , wherein the selected one of the stored values for the first interval or the second interval comprises an interval between the atrial event and an intrinsic ventricular event.
10 . The method of claim 9 , further comprising, by the processing circuitry: determining an interval between the atrial event and a paced ventricular event based on the selected one of the stored values for the first interval or the second interval; and controlling the therapy delivery circuitry of the implantable medical device system to deliver the pacing therapy at the determined interval between the atrial event and the paced ventricular event.
11 . A system for controlling delivery of pacing therapy, the system comprising: therapy delivery circuitry configured to deliver pacing therapy to a heart of a patient; sensing circuitry configured to sense electrical activity of the heart; memory circuitry configured to store, in association with each of a plurality of heart rates, a respective value for each of a first interval between an intrinsic atrial event and a ventricular event and a second interval between a paced atrial event and the ventricular event; and processing circuitry configured to: determine the heart rate of a patient based on the electrical activity sensed by the sensing circuitry; determine whether an atrial event was intrinsic or paced; select one of the stored values, wherein the stored values comprise the stored value for the first interval between the intrinsic atrial event and the ventricular event associated with the determined heart rate, and the stored value for the second interval between the paced atrial event and the ventricular event associated with the determined heart rate based on the determination of whether the atrial event was intrinsic or paced; compare the selected one of the stored values to a threshold value; and control the therapy delivery circuitry to deliver the pacing therapy based on the comparing of the selected one of the stored values and the threshold value, wherein the pacing therapy comprises fusion pacing or biventricular pacing.
12 . The system of claim 11 , wherein the processing circuitry is configured to determine whether to control the therapy delivery circuitry to deliver fusion pacing or biventricular pacing based on the selected one of the stored values.
13 . The system of claim 12 , wherein the processing circuitry is configured to: control the therapy delivery circuitry to deliver fusion pacing in response to the selected one of the stored values being less than the threshold value.
14 . The system of claim 13 , wherein the fusion pacing includes left ventricular pacing.
15 . The system of claim 11 , wherein the processing circuitry is configured to control the therapy delivery circuitry to deliver the pacing therapy for a current cardiac cycle, and determine the heart rate of a preceding cardiac cycle.
16 . The system of claim 12 , wherein the processing circuitry is configured to select the one of the stored values and determine whether to control the therapy delivery circuitry to deliver fusion pacing or biventricular pacing for each of a plurality of consecutive cardiac cycles.
17 . The system of claim 12 , wherein the processing circuitry is configured to periodically: determine the heart rate of the patient; select either the stored value for the first interval or the stored value for the second interval associated with the determined heart rate; suspend the delivery of pacing therapy; while the delivery of pacing therapy is suspended, measure a current value of the either of the first interval or the second interval; compare the current value of the either of the first interval or the second interval to the selected value of the either of the first interval or the second interval; and update at least the selected value of the either of the first interval or the second interval associated with the determined heart rate in the memory based on the comparison.
18 . The system of claim 11 , wherein the respective value for the first interval and the respective value for the second interval comprise a first value for the first interval and a first value for the second interval associated with a waking state of the patient and a second value of the first interval and a second value of the second interval associated with a sleeping state of the patient.
19 . The system of claim 11 , wherein the selected one of the stored values for the first interval or the second interval comprises an interval between the atrial event and an intrinsic ventricular event.
20 . The system of claim 19 , wherein the processing circuitry is configured to: determine an interval between the atrial event and a paced ventricular event based on the selected one of the stored values for the first interval or the second interval; and control the therapy delivery circuitry to deliver the pacing therapy at the determined interval between the atrial event and the paced ventricular event.

Description

This application is a continuation of U.S. application Ser. No. 17/391,389, filed Aug. 2, 2021, which is a continuation of U.S. application Ser. No. 15/418,046, filed Jan. 27, 2017, which issued as U.S. Pat. No. 11,077,306 on Aug. 3, 2021, the entire contents of each are incorporated herein by reference. TECHNICAL FIELD The disclosure relates generally to medical device systems and, more particularly, cardiac therapy delivery by implantable medical devices. BACKGROUND Some types of implantable medical devices, such as cardiac pacemakers or implantable cardioverter defibrillators, provide therapeutic electrical stimulation to a heart of a patient via electrodes of one or more implantable leads. The therapeutic electrical stimulation may be delivered to the heart in the form of pulses or shocks for pacing, cardioversion or defibrillation. In some cases, an implantable medical device may sense intrinsic depolarizations of the heart, and control the delivery of therapeutic stimulation to the heart based on the sensing. Cardiac resynchronization therapy (CRT) is one type of therapy delivered by an implantable medical device. Cardiac resynchronization therapy may help enhance cardiac output by resynchronizing the electromechanical activity of the ventricles of the heart. Ventricular desynchrony may occur in patients that suffer from congestive heart failure (CHF). SUMMARY In general, this disclosure is directed to techniques for controlling the delivery of CRT. Such techniques may include determining an interval between an atrial event and a ventricular event of a patient, and determining whether to deliver fusion pacing therapy, i.e., CRT pacing delivered to one of the ventricles, such as the left ventricle, or biventricular pacing therapy to the patient based on the determined interval. In some examples, the value of an interval between the atrial event and the ventricular event, e.g., an intrinsic ventricular event, may be obtained by periodically suspending the delivery of therapy and determining the current value of the interval. However, the act of suspending the delivery of therapy and determining a current value of the interval may result in a loss of delivery of CRT pacing to the patient. Since increased CRT pacing may be associated with improved patient outcome, it therefore may be desirable to decrease the frequency at which the current value of the interval between the atrial event and the ventricular event is determined. Accordingly, techniques described herein may include determining a heart rate of a patient and selecting from a table, based on the heart rate, a respective value for the interval between the atrial event and the ventricular event. In this manner, the interval to be used for determining whether to apply fusion pacing therapy or biventricular pacing therapy may be obtained without suspending the delivery of therapy. In techniques described herein, the suspension of the delivery of therapy to determine the current value of the interval thus may be limited to relatively infrequent occasions, such periodic updates to the table. In one example, a method for controlling delivery of cardiac resynchronization therapy (CRT) comprises storing, in a memory of an implantable medical device system and in association with each of a plurality of heart rates, at least one respective value for an interval between an atrial event and a ventricular event; and by processing circuitry of the implantable medical device system: determining a heart rate of a patient; selecting one of the stored values for the interval between the atrial event and the ventricular event associated with the determined heart rate; and determining whether to control therapy delivery circuitry of the implantable medical device system to deliver fusion pacing or biventricular pacing based on the selected one of the stored values for the interval between the atrial event and the ventricular event. In another example, a system for controlling delivery of cardiac resynchronization therapy (CRT) comprises therapy delivery circuitry configured to deliver cardiac resynchronization pacing therapy to a heart of a patient; sensing circuitry configured to sense electrical activity of the heart; memory configured to store, in association with each of a plurality of heart rates, at least one respective value for an interval between the atrial event and the ventricular event; and processing circuitry configured to: determine the heart rate of a patient based on the electrical activity sensed by the sensing circuitry; select one of the stored values for the interval between the atrial event and the ventricular event associated with the determined heart rate; and determine whether to control the therapy delivery circuitry to deliver fusion pacing or biventricular pacing based on the selected one of the stored values for the interval between the atrial event and the ventricular event. In another example, an implantable medical device (IMD) config