US 7,079,896 B1 · Methods of automatically optimizing AV delay by way of monitoring the heart sound

Abstract

An implantable cardiac stimulator including and accelerometer utilizes heart sound measurements to optimize the AV delay. One or more of the amplitude of the heart sound, the pre-ejection interval or the ejection interval is derived from the measurements and examined at various values of AV delay. The optimal AV delay is selected that corresponds to the highest cardiac function such as contractility, cardiac output and stroke volume. The stimulation device determines when the patient is at rest and the accelerometer provides a signal that corresponds to the audible component of a vibration produced as a result of ventricular contraction, blood movement toward the atrium, and the opening and closing of valves. The AV delay is adjusted within a range of values and the cardiac parameters are determined multiple times for each AV delay value. The average value of the cardiac parameter is examined to determine the optimal AV delay value.

Claims23

Dependent claims

In an implantable cardiac stimulation device for implant in a patient, said stimulation device having an accelerometer-based activity sensor and an adjustable AV delay, a method for optimizing said AV delay comprising:

determining when the patient is in a rest condition;
detecting the occurrence of R-waves when a rest condition is determined;
adjusting the AV delay through a range of values while monitoring an acceleration signal upon the occurrence of each R-wave;
storing the values of said acceleration signals in association with the corresponding values of the AV delay;
and
selecting the AV delay corresponding to the acceleration signal indicative of the highest cardiac contractility;
wherein monitoring an acceleration signal comprises detecting a maximum peak-to-peak accelerometer signal (S1) within a first pre-defined interval.

4 more elements

An implantable cardiac stimulation device comprising:

a pulse generator adapted to deliver cardiac stimulation pulses to at least a ventricle of a patient's heart, the timing of delivery of such stimulation pulses being a function of an AV delay;
an accelerometer, mounted within a housing, that senses heart sounds, the accelerometer being operative to provide accelerometer signals corresponding to sensed heart sounds;
a control circuit coupled to the pulse generator and operative to adjust the AV delay through a plurality of AV delay values;
and
a monitoring circuit coupled to the accelerometer and operative to determine an optimal AV delay value based up the accelerometer signal corresponding to a maximum detected heart sound;
wherein the monitoring circuit monitors cardiac pre-election interval as a measure of cardiac contractility;
wherein the control circuit adjusts the AV delay to the optimal AV delay value;
and
wherein the pre-ejection interval (PEI) comprises calculating the PEI from the equation PEI=TS1−T0 where T0 is the time of occurrence of an R-wave and TS1 is calculated from the equation:
T
S
⁢
⁢
1
=
∑
t
=
T
0
T
0
+
R
⁢
⁢
T
⁢
⁢
A
t
·
(
t
-
T
0
)
∑
t
=
T
0
T
0
+
R
⁢
⁢
T
⁢
⁢
A
t
where At is the instantaneous value of the accelerometer signal at time t and RT is the time interval between the R-wave and the immediately following T-wave.

52 more elements

Dependencies are inferred from the claim text.

Methods of automatically optimizing AV delay by way of monitoring the heart sound

Life of this patent

Methods of automatically optimizing AV delay by way of monitoring the heart sound

Life of this patent

Abstract

Claims23