Insertable cardiac monitor for use in performing long term electrocardiographic monitoring

• US 10,624,551 B2
• Filed: 11/01/2018
• Issued: 04/21/2020
• Est. Priority Date: 09/25/2013
• Status: Active Grant

• Current Assignee: Bardy Diagnostics, Inc. (Baxter International Inc.)
• Original Assignee: Bardy Diagnostics, Inc. (Baxter International Inc.)
• Inventors: Bardy, Gust H., Felix, Jason
• Primary Examiner(s): Marlen, Tammie K
• Application Number:
  US16/178,455
• Publication Number:
  US 20190150776A1
• Time in Patent Office: 537 Days
• CPC Class Codes: A61B 2505/07 Home care
• CPC Class Codes: A61B 2560/0271 using a remote monitoring unit
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2560/045 with a separable interface unit, e.g. for communication
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1117 Fall detection
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/259 : using conductive adhesive means, e.g. gels
• CPC Class Codes: A61B 5/282 : Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/316 : Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/335 : using integrated circuit memory devices
• CPC Class Codes: A61B 5/349 : Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/35 : by template matching
• CPC Class Codes: A61B 5/4809 : Sleep detection, i.e. determining whether a subject is asleep or not
• CPC Class Codes: A61B 5/6801 : specially adapted to be attached to or worn on the body surface
• CPC Class Codes: A61B 5/6823 : Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6833 : Adhesive patches
• CPC Class Codes: A61B 5/7455 : characterised by tactile indication, e.g. vibration or electrical stimulation
• CPC Class Codes: G01N 27/307 : Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G16H 40/67 : for remote operation

Abstract

Long-term electrocardiographic and physiological monitoring over a period lasting up to several years in duration can be provided through a continuously-recording subcutaneous insertable cardiac monitor (ICM). The sensing circuitry and the physical layout of the electrodes are specifically optimized to capture electrical signals from the propagation of low amplitude, relatively low frequency content cardiac action potentials, particularly the P-waves that are generated during atrial activation and storing samples of captured signals. In general, the ICM is intended to be implanted centrally and positioned axially and either over the sternum or slightly to either the left or right of the sternal midline in the parasternal region of the chest.

Claims

1. An insertable cardiac monitor (ICM) for use in performing long term electrocardiographic (ECG) monitoring, comprising:

an implantable housing comprised of a biocompatible material that is suitable for implantation within a living body;

at least one pair of ECG sensing electrodes provided on a ventral surface and on opposite ends of the implantable housing; and

electronic circuitry provided within the housing, comprising;

an ECG front end circuit interfaced to a low-power microcontroller and configured to capture cardiac action potentials sensed by the at least one pair of ECG sensing electrodes which are output as ECG signals;

the low power microcontroller configured to execute under modular micro program control as specified in firmware, the microcontroller configured to read samples of the ECG signals, buffer the samples of the ECG signals, compress the buffered samples of the ECG signals, buffer the compressed samples of the ECG signals, and write the compressed buffered samples into a non-volatile flash memory; and

the non-volatile memory electrically interfaced with the microcontroller and configured to store the written samples of the ECG signals.

2. A monitor according to claim 1, further comprising:

a power up sequence stored as part of the firmware, wherein the microcontroller is configured to execute the power up sequence upon the monitor being implanted into the body.

3. A monitor according to claim 2, the power up sequence comprising one or more of a battery voltage checking procedure, a flash memory state checking procedure, and a microcontroller diagnostic procedure.

4. A monitor according to claim 1, further comprising:

an actigraphy sensor electrically interfaced with the microcontroller and configured to sense actigraphy event occurrences based on movement of the sensor using an actigraphy event occurrence criteria and to send an interrupt signal to the micro-controller upon sensing each of the actigraphy event occurrences.

5. A monitor according to claim 4, wherein the actigraphy sensor comprises a 3-axis accelerometer.

6. A monitor according to claim 4, wherein the actigraphy event occurrences comprise at least one of a fall and a postural change.

7. A monitor according to claim 1, further comprising:

a battery comprised within the implantable housing and which powers the electronic circuitry.

8. A monitor according to claim 1, further comprising:

one or more memory storage locations comprised in the non-volatile memory in which the written samples of the ECG signals are stored,

wherein, upon all of the memory storage locations being filled, the microcontroller is configured to overwrite the written samples of the ECG signals stored in one of the memory storage locations to store the written samples of the ECG signals acquired after the written samples being overwritten.

9. A monitor according to claim 1, further comprising:

one or more memory storage locations comprised in the non-volatile memory in which the written samples of the ECG signals are stored; and

a transceiver interfaced to the microcontroller and configured to wirelessly interface to an external device and provide the stored written samples of the ECG signals from the non-volatile memory upon all of the memory storage locations being filled.

10. A subcutaneous implantable loop recorder for long term electrocardiographic (ECG) monitoring, comprising:

a hermetically sealed implantable housing defining a rectangular shape with rounded edges and comprised of a biocompatible material that is suitable for implantation within a living body of a patient;

at least one pair of ECG sensing electrodes provided on a ventral surface and on opposite ends of the implantable housing;

electronic circuitry provided within the housing, the electronic circuitry comprising;

an ECG front end circuit interfaced to a low-power microcontroller and configured to capture cardiac action potentials sensed by the at least one pair of ECG sensing electrodes which are output as ECG signals;

the low power microcontroller configured to execute under modular micro program control as specified in firmware, the microcontroller configured to read samples of the ECG signals, buffer the samples of the ECG signals, compress the buffered samples of the ECG signals, buffer the compressed samples of the ECG signals, and write the compressed buffered samples into a non-volatile flash memory; and

the non-volatile memory electrically interfaced with the microcontroller and configured to store the written samples of the ECG signals.

11. A recorder according to claim 10, further comprising:

a power up sequence stored as part of the firmware, wherein the microcontroller is configured to execute the power up sequence upon the monitor being implanted into the body.

12. A recorder according to claim 11, the power up sequence comprising one or more of a battery voltage checking procedure, a flash memory state checking procedure, and a microcontroller diagnostic procedure.

13. A recorder according to claim 10, further comprising:

an actigraphy sensor electrically interfaced with the microcontroller and configured to sense actigraphy event occurrences based on movement of the sensor using an actigraphy event occurrence criteria and to send an interrupt signal to the micro-controller upon sensing each of the actigraphy event occurrences.

14. A recorder according to claim 13, wherein the actigraphy sensor comprises a 3-axis accelerometer.

15. A recorder according to claim 13, wherein the actigraphy event occurrences comprise at least one of a fall and a postural change.

16. A recorder according to claim 10, further comprising:

a battery comprised within the implantable housing and which powers the electronic circuitry.

17. A recorder according to claim 10, further comprising:

one or more memory storage locations comprised in the non-volatile memory in which the written samples of the ECG signals are stored,

wherein, upon all of the memory storage locations being filled, the microcontroller is configured to overwrite the written samples of the ECG signals stored in one of the memory storage locations to store the written samples of the ECG signals acquired after the written samples being overwritten.

18. A recorder according to claim 10, further comprising:

one or more memory storage locations comprised in the non-volatile memory in which the written samples of the ECG signals are stored; and

a transceiver interfaced to the microcontroller and configured to wirelessly interface to an external device and provide the stored written samples of the ECG signals from the non-volatile memory upon all of the memory storage locations being filled.