# US 2016/0250480 A1 · Monitoring of pacing capture using acceleration

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2016/0250480 A1
- Document ID: US20160250480A1
- Status: Published application
- Kind: A1
- Application number: 14/681,223
- Filed: 2015-04-08
- Published: 2016-09-01
- Earliest claimed: 2015-02-26
- Assignees: Medtronic, Inc.
- Applicants: Medtronic, Inc.
- Inventors: Todd J. Sheldon; David M. Steinhaus
- Web page: https://patentgrep.com/patent/US20160250480A1

## CPC

- A61N 1/3712: {Auto-capture, i.e. automatic adjustment of the stimulation threshold}
- A61N 1/36542: {controlled by body motion, e.g. acceleration}
- A61N 1/36578: {controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone}
- A61N 1/36507: {controlled by gradient or slope of the heart potential}
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)

## Abstract

An implantable medical device includes an activity sensor, a pulse generator, and a control module. The control module is configured to determine an activity metric from the activity sensor signal over an activity metric interval and compare the activity metric to a loss of capture detection threshold. The control module may detect loss of capture in response to the activity metric being less than the loss of capture detection threshold and increase a pacing pulse output in response to detecting the loss of capture.

## Claims

### Claim 1

A method for detecting loss of pacing capture responsive to therapy delivery by an implantable medical device, comprising:
delivering pacing pulses to a heart of a patient;
sensing an activity sensor signal comprising motion signals due to motion of the heart and motion signals due to physical activity of the patient;
computing an activity metric from the activity sensor signal over an activity metric interval;
comparing the activity metric to a loss of capture detection threshold;
detecting loss of capture by the delivered pacing pulses in response to the activity metric being less than the loss of capture detection threshold; and
increasing a pacing pulse output in response to detecting the loss of capture.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
determining a sensor indicated pacing rate based on the activity metric; and
setting a pacing pulse rate in response to the sensor indicated pacing rate.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
adjusting at least one of the loss of capture detection threshold and the activity metric interval responsive to the pacing rate being set at a sensor indicated pacing rate that is greater than a predetermined base rate.

### Claim 4 (depends on 1)

The method of claim 1, wherein computing the activity metric comprises one of:
rectifying the activity sensor signal and counting a number of activity threshold crossings of the activity sensor signal during the activity metric interval, and
rectifying the activity sensor signal and summing all sample point amplitudes of the rectified activity sensor signal during the activity metric interval.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
accumulating a plurality of activity metric values;
establishing the loss of capture detection threshold based on at least a portion of the plurality of activity metric values.

### Claim 6 (depends on 5)

The method of claim 5, further comprising sensing a cardiac electrical signal,
wherein accumulating the plurality of activity metric values comprises:
performing a capture threshold search to determine a capture threshold indicated by the sensed cardiac electrical signal; and
accumulating the plurality of activity metric values during the capture threshold search,
wherein the loss of capture detection threshold is established based on the accumulated plurality of activity metric values during the capture threshold search.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
performing a capture threshold search to determine a capture threshold responsive to detecting the loss of capture;
comparing the determined capture threshold to a previously determined capture threshold; and
adjusting a loss of capture detection control parameter in response to the determined capture threshold being equal to or less than the previously determined capture threshold.

### Claim 8 (depends on 7)

The method of claim 7, wherein adjusting the loss of capture detection control parameter comprises decreasing the loss of capture threshold.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
determining if a sensed R-wave occurs during the activity metric interval; and
adjusting a loss of capture detection control parameter responsive to a sensed R-wave during the activity metric interval.

### Claim 10 (depends on 9)

The method of claim 9, wherein adjusting the loss of capture detection control parameter comprises at least one of increasing the loss of capture detection threshold and increasing a number of activity metrics.

### Claim 11 (depends on 1)

The method of claim 1, further comprising:
detecting an occurrence of capture subsequent to increasing the pacing pulse output;
if capture is not detected, adjusting the pacing pulse output in successive increments up to a maximum pacing pulse output until capture is detected; and
recording a date and time stamp in response to the maximum pacing pulse output being reached without detection of capture.

### Claim 12

An implantable medical device, comprising:
an activity sensor configured to generate a signal indicative of motion of a heart of a patient and physical activity of the patient;
a pulse generator configured to generate and deliver pacing pulses to the patient's heart via a pair of electrodes coupled to the implantable medical device; and
a control module coupled to the pulse generator and the activity sensor, the control module being configured to:
compute an activity metric from the activity sensor signal over an activity metric interval;
compare the activity metric to a loss of capture detection threshold;
detect loss of capture by the delivered pacing pulses in response to the activity metric being less than the loss of capture detection threshold; and
increase a pacing pulse output in response to detecting the loss of capture.

### Claim 13 (depends on 12)

The device of claim 12, wherein the control module is further configured to:
determine a sensor indicated pacing rate based on the activity metric; and
set a pacing pulse rate responsive to the sensor indicated pacing rate.

### Claim 14 (depends on 13)

The device of claim 13, wherein the control module is further configured to:
adjust at least one of the loss of capture detection threshold and the activity metric interval responsive to the pacing rate being set at a sensor indicated pacing rate that is greater than a predetermined base rate.

### Claim 15 (depends on 12)

The device of claim 12, wherein the control module is configured to determine the activity metric by one of:
rectifying the activity sensor signal and counting a number of activity threshold crossings of the activity sensor signal during the activity metric interval, and
rectifying the activity sensor signal and summing all sample point amplitudes of the rectified activity sensor signal during the activity metric interval.

### Claim 16 (depends on 12)

The device of claim 12, wherein the control module is further configured to:
accumulate a plurality of activity metric values; and
establish the loss of capture detection threshold based on at least a portion of the plurality of activity metric values.

### Claim 17 (depends on 16)

The device of claim 16, further comprising a sensing module for sensing a cardiac electrical signal, wherein the control module is further configured to:
accumulate the plurality of activity metric values by:
performing a capture threshold search to determine a capture threshold indicated by the sensed cardiac electrical signal; and
accumulating the plurality of activity metric values during the capture threshold search, wherein the loss of capture detection threshold is established based on the at least one of the plurality of activity metric values accumulated during the capture threshold search.

### Claim 18 (depends on 12)

The device of claim 12, wherein the control module is further configured to:
perform a capture threshold search to determine a capture threshold in response to detecting the loss of capture;
compare the determined capture threshold to a previously determined capture threshold; and
adjust a loss of capture detection control parameter in response to the determined capture threshold being equal to or less than the previously determined capture threshold.

### Claim 19 (depends on 18)

The device of claim 18, wherein the control module is configured to adjust the loss of capture detection control parameter by decreasing the loss of capture threshold.

### Claim 20 (depends on 12)

The device of claim 12, further comprising a sensing module configured to receive a cardiac electrical signal,
wherein the control module is further configured to:
receive cardiac sense event signals from the sensing module,
determine if a sensed event occurs during the activity metric interval; and
responsive to occurrence of the sensed event during the activity metric interval, adjusting a loss of capture detection control parameter.

### Claim 21 (depends on 20)

The device of claim 20, wherein the control module is configured to adjust the loss of capture detection control parameter by at least one of increasing the loss of capture detection threshold and increasing a number of activity metrics less than the loss of capture detection threshold that are required to detect the loss of capture.

### Claim 22 (depends on 12)

The device of claim 12, further comprising a memory,
wherein the control module is further configured to:
detect an occurrence of capture subsequent to increasing the pacing pulse output;
if capture is not detected, adjust the pacing pulse output incrementally up to a maximum pacing pulse output until capture is verified; and
record a date and time stamp in the memory in response to the maximum pacing pulse output being reached without the detection of capture.

### Claim 23

A non-transitory, computer readable storage medium storing a set of instructions that, when executed by a control module of an implantable medical device, cause the device to:
deliver pacing pulses to a heart of a patient;
sense an activity sensor signal comprising motion signals due to motion of the heart and motion signals due to physical activity of the patient;
determine an activity metric from the activity sensor signal over an activity metric interval;
compare the activity metric to a loss of capture detection threshold;
detect loss of capture of the delivered pacing pulses in response to the activity metric being less than the loss of capture detection threshold; and
increase a pacing pulse output in response to detecting the loss of capture.