TEMPORAL CONFIGURATION OF A MOTION SENSOR IN AN IMPLANTABLE MEDICAL DEVICE

• US 20170056665A1
• Filed: 08/22/2016
• Published: 03/02/2017
• Est. Priority Date: 08/27/2015
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kane, Michael J., Linder, William J., Haasl, Benjamin J., Huelskamp, Paul, Maile, Keith R., Balczewski, Ron A., Mi, Bin, Hatlestad, John D., Shuros, Allan Charles
• Granted Patent: US 9,956,414 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1107 Measuring contraction of parts of the body, e.g. organ, muscle apparatus for measuring work or force in general G01L
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/6869 Heart
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators

Abstract

Methods and devices for configuring the use of a motion sensor in an implantable cardiac device. The electrical signals of the patient'"'"'s heart are observed and may be correlated to the physical motion of the heart as detected by the motion sensor of the implantable cardiac device in order to facilitate temporal configuration of motion sensor data collection that avoids detecting cardiac motion in favor of overall motion of the patient.

Claims

1. A method of operating an implantable device comprising:

initializing an implantable device (ID) for disposition within the heart of a patient, the ID comprising a motion sensor for detecting movement of the patient, the initializing step being performed by;

contemporaneously collecting a set of data points from the motion sensor and from a cardiac electrical signal;

correlating time periods within the set of data points from the motion sensor to cardiac activity reflected by the cardiac electrical signal; and

configuring the ID to capture data from the motion sensor by reference to specific repeatable elements of the cardiac electrical signal;

using the ID as configured in the initializing step to capture cardiac signals of the patient and motion signals for the patient.

2. The method of claim 1 further comprising;

using the motion signals to determine an activity level of the patient; and

setting and implementing a pacing rate for the patient using the determined activity level.

3. The method of claim 1 wherein the step of configuring the ID to capture data from the motion sensor is performed by:

determining when intrinsic mechanical motion of the heart is detected by the motion sensor relative to electrical signals of the heart; and

setting a data capture period for the motion sensor relative to a specified electrical signal of the heart to avoid capturing the intrinsic mechanical motion of the heart with the motion sensor.

4. The method of claim 1 wherein the step of configuring the ID to capture data from the motion sensor includes determining a delay after a T-wave in the cardiac electrical signal.

5. The method of claim 4 wherein the delay is configured as a function of cardiac rate.

6. The method of claim 5 wherein the cardiac rate is determined as a rate of pacing output of the ID.

7. The method of claim 5 wherein the cardiac rate is determined as an intrinsic rate of the patient'"'"'s heart.

8. A method of operating a motion sensor in an implantable device (ID) for disposition within the heart of a patient, the ID comprising a motion sensor for detecting movement of the patient, the method comprising:

the ID determining a predefined event has occurred in the heart of the patient; and

the ID waiting a predetermined period of time after the predefined electrical event and sampling an output of the motion sensor.

9. The method of claim 8 further comprising duty cycling the motion sensor to operate in a window corresponding to the sampling step and otherwise be in a low-power state.

10. The method of claim 8 wherein the predefined event is one of an R-wave, a pacing pulse, or a QRS complex, and the predetermined time period is selected to expire prior to occurrence of a P-wave.

11. The method of claim 8 further comprising using the output of the motion sensor to determine whether the patient is physically active to facilitate a rate-responsive pacing therapy by the ID.

12. The method of claim 8 further comprising using the output of the motion sensor to determine an increase or decrease in cardiac contractility to facilitate a rate-responsive pacing therapy by the ID.

13. The method of claim 8 further comprising determining the predetermined period of time by initializing the ID by capturing a plurality of outputs from the motion sensor over a period of time including several heart beats to determine a mechanically quiet period in the patient'"'"'s cardiac cycle relative to the predefined event.

14. The method of claim 8 wherein the predefined event is one of a P-wave, an R-wave, a QRS complex, a T-wave, or a quiescent period.

15. The method of claim 8 wherein the predefined event is delivery of a pacing stimulus.

16. The method of claim 8 further comprising analyzing a cardiac electrical signal of the patient during at least the predetermined period of time to observe whether a specified cardiac electrical event occurs and, if so, discarding the sampled output of the motion sensor.

17. The method of claim 16 wherein the specified cardiac event is a ventricular contraction.

18. A method of determining whether a patient is active using an implantable device (ID) for disposition within the heart of a patient, the ID comprising a motion sensor for detecting movement of the patient, the method comprising:

sampling a signal from a motion sensor in the ID;

analyzing the sampled signal over time to generate a baseline;

generating a present state indicator from the sampled signal;

comparing the present state indicator to the baseline to yield a difference; and

comparing the difference to one or more thresholds to characterize the patient'"'"'s activity level.

19. The method of claim 18 wherein:

the present state indicator is generated by averaging a number, M, of individual samples from the motion sensor;

the subtractive baseline is generated by averaging a number, N, of individual samples from the motion sensor; and

wherein M is an order of magnitude smaller than N.

20. The method of claim 18 further comprising:

providing a pacing output from the ID to the patient'"'"'s heart, wherein the pacing output has a rate which is adjustable; and

adjusting the pacing output rate in light of the patient'"'"'s activity level.