# US 2026/0284418 A1 · Medical device fixation integrity monitoring and alert

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- Number: US 2026/0284418 A1
- Document ID: US20260284418A1
- Status: Published application
- Kind: A1
- Application number: 19/469,851
- Filed: 2024-03-12
- Published: 2026-09-24
- Earliest claimed: 2023-03-31
- Assignees: Medtronic, Inc.
- Applicants: Medtronic, Inc.
- Inventors: Michael P. CAMPBELL; Kevin T. O'BRIEN
- Web page: https://patentgrep.com/patent/US20260284418A1

## CPC

- A61N 1/36578: {controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone}
- A61N 1/37518: {Anchoring of the implants, e.g. fixation}
- A61B 5/0031: {Implanted circuitry}
- A61B 5/067: {using accelerometers or gyroscopes}
- A61B 5/686: {Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence)}
- A61N 1/36585: {controlled by two or more physical parameters}
- A61N 1/37: Monitoring; Protecting
- A61N 1/3925: {Monitoring; Protecting}
- A61B 5/1116: {Determining posture transitions}
- A61B 5/6882: {Anchoring means}
- A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)}
- A61B 2560/0276: Determining malfunction
- A61B 2562/0219: Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
- A61N 1/36542: {controlled by body motion, e.g. acceleration}
- A61N 1/3756: {Casings with electrodes thereon, e.g. leadless stimulators}
- 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)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

An implantable medical device (IMD) is configured to sense an axis signal along a plurality of axes of a motion sensor of the IMD. The IMD is configured to, for multiple time periods determine a metric from the axis signals. Each of the multiple time periods extend over multiple cardiac cycles. The IMD may determine that the metrics determined for at least a plurality of the multiple time periods meet a dislodgement threshold and detect dislodgement of the IMD in response to the metrics determined for at least the plurality of multiple time periods meeting the dislodgement threshold.

## Claims

### Claim 1

An implantable medical device (IMD) comprising:
a motion sensor configured to sense an axis signal along a plurality of axes of the motion sensor;
a sensing circuit configured to sense cardiac event signals attendant to myocardial depolarizations;
a pulse generator configured to generate cardiac pacing pulses; and
a control circuit in communication with the motion sensor, the sensing circuit and the pulse generator, the control circuit configured to:
determine a first signal from the axis signals sensed over multiple time periods that each extend over a plurality of cardiac cycles;
for each of the multiple time periods, determine a metric from the first signal;
determine that the metrics determined for at least a plurality of the multiple time periods meet a dislodgement threshold; and
detect dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold; and
a communication circuit configured to transmit an IMD dislodgement alert in response to the control circuit detecting the dislodgement.

### Claim 2 (depends on 1)

The IMD of claim 1 wherein the control circuit is further configured to:
identify cardiac cycles based on at least one of the cardiac event signals sensed by the sensing circuit or the cardiac pacing pulses generated by the pulse generator;
determine a peak amplitude of the first signal during each of a plurality of the identified cardiac cycles; and
determine the metric based on the peak amplitudes.

### Claim 3 (depends on 2)

The IMD of claim 2 wherein the control circuit is further configured to:
detect an electrical indicator of dislodgement by determining at least one of:
a pacing impedance;
a pacing capture threshold;
a sensed cardiac event amplitude;
a loss of pacing capture;
evidence of undersensing of cardiac event signals; or
an increase in pacing burden; and
detect the dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold and detecting the electrical indicator of dislodgement.

### Claim 4 (depends on 2)

The IMD of claim 2 wherein the control circuit is further configured to determine the metric based on the peak amplitudes by:
for each of the peak amplitudes, determining a peak time of the peak amplitude relative to the corresponding identified cardiac cycle; and
determining the metric based on the peak times.

### Claim 5 (depends on 1)

The IMD of claim 1 wherein the control circuit is further configured to:
filter the axis signals according to a first frequency range;
determine the first signal by determining a combination of the axis signals filtered according to the first frequency range;
filter the axis signals according to a second frequency range;
determine a second signal from a combination of the axis signals filtered according to the second frequency range; and
determine the metric by determining a difference between the first signal and the second signal.

### Claim 6 (depends on 5)

The IMD of claim 5 wherein the control circuit is further configured to:
identify cardiac cycles based on at least one of the cardiac event signals sensed by the sensing circuit or the cardiac pacing pulses generated by the pulse generator;
determine a first peak amplitude of the first signal during each of a plurality of the identified cardiac cycles;
determine a second peak amplitude of the second signal during each of the plurality of the identified cardiac cycles; and
determine the difference between the first signal and the second signal based on the first peak amplitudes and the second peak amplitudes.

### Claim 7 (depends on 1)

The IMD of claim 1 wherein the control circuit is further configured to:
determine a baseline orientation signal from the axis signals at a baseline time point;
for at least one of the multiple time periods, determine a new orientation signal from the axis signals;
determine an orientation change metric based on a difference between the new orientation signal and the baseline orientation signal;
determine that the orientation change metric meets an orientation change threshold; and
detect the dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold and the orientation change metric meeting the orientation change threshold.

### Claim 8 (depends on 7)

The IMD of claim 7 wherein the control circuit is further configured to determine the orientation change metric by determining at least one of:
a difference between an average amplitude of the new orientation signal and an average amplitude of the baseline orientation signal; or
a difference between an angle defined by an average amplitude of the orientation signal and an angle defined by an average amplitude of the baseline orientation signal.

### Claim 9 (depends on 7)

The IMD of claim 7 wherein:
the communication circuit is further configured to receive a second device orientation signal at the baseline time point and the at least one of the multiple time periods; and
the control circuit is further configured to:
determine a baseline IMD to second device orientation metric from the second device orientation signal received at the baseline time point and the baseline orientation signal;
for at least one of the multiple time periods, determine a new IMD to second device orientation metric from the second device orientation signal received for the at least one of the multiple time periods and the new orientation signal received for the at least one of the multiple time periods;
detect an IMD orientation change based on the baseline IMD to second device orientation metric and the new IMD to second device orientation metric; and
detect the dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold and the detected IMD orientation change.

### Claim 10 (depends on 1)

The IMD of claim 1 wherein the control circuit is further configured to:
detect a sign change in at least one of the axis signals from a baseline time point to at least one of the multiple time periods; and
detect the dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold and the detected sign change.

### Claim 11 (depends on 1)

The IMD of claim 1 wherein the control circuit is further configured to:
determine a long term trend value of the metric;
determine the dislodgement threshold based on the long term trend value.

### Claim 12 (depends on 1)

The IMD of claim 1 further comprising:
a housing enclosing the motion sensor, sensing circuit, pulse generator and the control circuit;
a plurality of electrodes on the housing; and
a fixation member extending from the housing for anchoring the IMD at an implant site.

### Claim 13 (depends on 12)

The IMD of claim 12 wherein at least one electrode of the plurality of electrodes is the fixation member.

### Claim 14 (depends on 1)

The IMD of claim 1 wherein, in response to detecting the dislodgement, the control circuit is configured to adjust at least one of:
a pacing control parameter used to control the pulse generator in generating the cardiac pacing pulses; or
a sensing control parameter used to control the sensing circuit in sensing the cardiac event signals.

### Claim 15 (depends on 1)

The medical device of claim 1 wherein the control circuit is further configured to:
determine a rectified axis signal from each of the axis signals sensed along the plurality of axes of the motion sensor; and
determine the first signal as a combination of the rectified axis signals.

### Claim 16

A method comprising:
sensing an axis signal along a plurality of axes of a motion sensor of an implantable medical device (IMD);
determining a first signal from the axis signals sensed over multiple time periods, the multiple time periods each extending over a plurality of cardiac cycles;
for each of the multiple time periods, determining a metric from the first signal;
determining that the metrics determined for at least a plurality of the multiple time periods meet a dislodgement threshold;
detecting dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold; and
transmitting an IMD dislodgement alert in response to detecting the dislodgement.

### Claim 17 (depends on 16)

The method of claim 16 further comprising:
filtering the axis signals according to a first frequency range;
determining the first signal by determining a combination of the axis signals filtered according to the first frequency range;
filtering the axis signals according to a second frequency range;
determining a second signal from a combination of the axis signals filtered according to the second frequency range; and
determining the metric by determining a difference between the first signal and the second signal.

### Claim 18 (depends on 16)

The method of claim 16 further comprising:
determining a baseline orientation signal from the axis signals at a baseline time point;
for at least one of the multiple time periods, determining a new orientation signal from the axis signals;
determining an orientation change metric based on a difference between the new orientation signal and the baseline orientation signal;
determining that the orientation change metric meets an orientation change threshold; and
detecting the dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold and the orientation change metric meeting the orientation change threshold.

### Claim 19 (depends on 18)

The method of claim 18 further comprising:
receiving a second device orientation signal at the baseline time point and the at least one of the multiple time periods;
determining a baseline IMD to second device orientation metric from the second device orientation signal received at the baseline time point and the baseline orientation signal;
for the at least one of the multiple time periods, determining a new IMD to second device orientation metric from the second device orientation signal received for the at least one of the multiple time periods and the new orientation signal determined for the at least one of the multiple time periods;
detecting an IMD orientation change based on the baseline IMD to second device orientation metric and the new IMD to second device orientation metric; and
detecting the dislodgement of the IMD in response to the metrics determined for at least the plurality of the multiple time periods meeting the dislodgement threshold and the detected IMD orientation change.

### Claim 20 (depends on 16)

The method of claim 16 further comprising:
determining a long term trend value of the metric; and
determining the dislodgement threshold based on the long term trend value.

### Claim 21

A non-transitory, computer-readable storage medium storing a set of instructions which, when executed by a control circuit of an implantable medical device (IMD), cause the IMD to:
sense an axis signal along a plurality of axes of a motion sensor of the IMD;
determine a signal from the axis signals sensed over multiple time periods, the multiple time periods each extending over a plurality of cardiac cycles;
for each of the multiple time periods, determine a metric from the signal;
determine that the metrics determined for at least a plurality of the multiple time periods meet a dislodgement threshold;
detect dislodgement of the IMD in response to the metrics determined for at least the plurality of multiple time periods meeting the dislodgement threshold; and
transmit an IMD dislodgement alert in response to detecting the dislodgement.