STANDALONE SYSTEMIC ARTERIAL BLOOD PRESSURE MONITORING DEVICE

• US 20090281399A1
• Filed: 05/29/2009
• Published: 11/12/2009
• Est. Priority Date: 08/31/2007
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Keel, Allen J., Wenzel, Brian Jeffrey, Hou, Wenbo, Karst, Edward, Fayram, Timothy A., Farazi, Taraneh Ghaffari, Fain, Eric S., Levine, Paul A.
• Granted Patent: US 8,162,841 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02158 provided with two or more sensor elements
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

Certain embodiments of the present invention are related to an implantable monitoring device to monitor a patient'"'"'s arterial blood pressure, where the device is configured to be implanted subcutaneously. The device includes subcutaneous (SubQ) electrodes and a plethysmography sensor. Additionally, the device includes an arterial blood pressure monitor configured to determine at least one value indicative of the patient'"'"'s arterial blood pressure based on at least one detected predetermined feature of a SubQ ECG and at least one detected predetermined feature of a plethysmography signal. Alternative embodiments of the present invention are directed to a non-implantable monitoring device to monitor a patient'"'"'s arterial blood pressure based on features of a surface ECG and a plethysmography signal obtained from a non-implanted sensor.

Claims

1. An implantable monitoring device to monitor a patient'"'"'s arterial blood pressure and configured to be implanted subcutaneously, the device comprising:

subcutaneous (SubQ) electrodes configured to obtain a subcutaneous electrocardiogram (SubQ ECG) that is indicative of electrical activity of the patient'"'"'s heart;

a plethysmography sensor configured to obtain a plethysmography signal indicative of changes in the patient'"'"'s arterial blood volume;

an arterial blood pressure monitor configured to

detect one or more predetermined feature of the SubQ ECG signal,

detect one or more predetermined feature of the plethysmography signal, and

determine at least one value indicative of the patient'"'"'s arterial blood pressure based on at least one said detected predetermined feature of the SubQ ECG and at least one said detected predetermined feature of the plethysmography signal.

2. The implantable monitoring device of claim 1, wherein:

the implantable monitoring device is configured to transfer the at least one value indicative of the patient'"'"'s arterial blood pressure to an non-implanted device;

the implantable monitoring device is not configured to pace the patient'"'"'s heart and not configured to defibrillate the patient'"'"'s heart; and

the at least one value indicative of the patient'"'"'s arterial blood pressure is/are indicative of diastolic pressure (DP), systolic pressure (SP), pulse pressure (PP), mean arterial pressure (MAP), a change in DP, a change in SP, a change in PP and/or a change in MAP.

3. The implantable monitoring device of claim 1, further comprising:

a housing within which the arterial blood pressure monitor is located; and

wherein the subq electrodes are attached to the housing.

4. The implantable monitoring device of claim 3, wherein the subQ electrodes are substantially flush with and/or adjacent to the housing.

5. The implantable monitoring device of claim 3, further comprising:

a housing within which the arterial blood pressure monitor is located;

wherein the subQ electrodes are remote from the housing and at least some of the SubQ electrodes are configured to be mounted subcutaneously outside of a patient'"'"'s rib cage.

6. The implantable monitoring device of claim 1, further comprising:

a housing within which the arterial blood pressure monitor is located;

wherein the plethysmography sensor is within, integral with or attached to the housing.

7. The implantable monitoring device of claim 6, wherein:

the plethysmography sensor comprises a photoplethysmography (PPG) sensor configured to obtain a photoplethysmography (PPG) signal indicative of changes in arterial blood volume; and

the PPG sensor comprises a light source and a light detector.

8. The implantable monitoring device of claim 7, wherein the light source and the light detector are within, integral with or attached to the housing.

9. The implantable monitoring device of claim 8, further comprising optical fibers that are configured to transmit light produced by the light source to a portion of the patient'"'"'s body that is remote from the housing, and to provide a portion of the transmitted light reflected from and/or transmitted through the portion of the patient'"'"'s body to the light detector.

10. The implantable monitoring device of claim 1, further comprising:

a housing within which the arterial blood pressure monitor is located; and

a lead that extends from the housing;

wherein the PPG sensor includes a light source and a light detector that are located within, integral with or attached to the lead that extends from the housing to thereby enable the light source and light detector to be placed at a location within the patient'"'"'s body that is remote from a location of the housing.

11. The implantable monitoring device of claim 1, wherein the arterial blood pressure monitor is configured to monitor changes in the patient'"'"'s arterial blood pressure based on changes in the determined at least one value indicative of the patient'"'"'s arterial blood pressure.

12. The implantable monitoring device of claim 1, wherein the one or more predetermined feature of the SubQ ECG signal that the arterial blood pressure monitor is configured to detect includes at least a ventricular depolarization, and can also include a ventricular repolarization.

13. The implantable monitoring device of claim 12, wherein the arterial blood pressure monitor is configured to detect one or more predetermined feature of the PPG selected from the group consisting of:

the minimum amplitude of the PPG signal;

the maximum upward slope of the PPG signal;

the maximum amplitude of the PPG signal;

the maximum downward slope of the PPG signal prior to the dicrotic notch;

the dicrotic notch of the PPG signal; and

the maximum downward slope of the PPG signal following the dicrotic notch.

14. The implantable monitoring device of claim 1, wherein the arterial blood pressure monitor is configured to:

determine a pulse arrival time (PAT) value by determining a time from a detected said predetermined feature of the SubQ ECG signal to a detected said predetermined feature of the PPG signal; and

determine at least one value indicative of the patient'"'"'s arterial blood pressure based on the PAT value.

15. The implantable monitoring device of claim 14, wherein the arterial blood pressure monitor is configured to determine a value indicative of systolic pressure (SP) based on the PAT value.

16. The implantable monitoring device of claim 15, wherein the arterial blood pressure monitor is configured to:

determining a peak-to-peak amplitude of the plethysmography signal indicative of changes in the patient'"'"'s arterial blood volume; and

determine a value indicative of diastolic pressure (DP) based on the peak-to-peak amplitude and the value indicative of SP.

17. The implantable monitoring device of claim 16, wherein the arterial blood pressure monitor is configured to determine the value indicative of DP by determining a value indicative of pulse pressure (PP) based on the peak-to-peak amplitude, and determine the value indicative of DP by subtracting the value indicative of PP from the value indicative of SP.

18. The implantable monitoring device of claim 17, wherein the arterial blood pressure monitor is configured to determine a value indicative of mean arterial pressure (MAP) based on the value indicative of SP and the value indicative of DP.

19. The implantable monitoring device of claim 1, wherein the arterial blood pressure monitor is configured to:

detect ventricular depolarizations and ventricular repolarizations in cardiac cycles represented in the SubQ ECG signal;

detect maximum peak amplitudes in cardiac cycles represented in the PPG signal;

determine a time t₁ from a detected ventricular depolarization to a detected maximum peak amplitude in the plethysmography signal;

determine a time t₂ from the detected ventricular repolarization to the detected maximum peak amplitude in the plethysmography signal;

determine a peak pulse arrival time (PPAT) based on times t₁ and t₂; and

determine a value indicative of systolic pressure (SP) based on the PPAT.

20. The implantable monitoring device of claim 19, wherein the arterial blood pressure monitor is configured to:

determine a peak-to-peak amplitudes a₁ in the PPG signal; and

determine a value indicative of diastolic pressure (DP) based on the amplitude al and the value indicative of SP.

21. The implantable monitoring device of claim 20, wherein the arterial blood pressure monitor is configured to:

determine a value indicative of mean arterial pressure (MAP) based on the value indicative of SP and the value indicative of DP.

22. The implantable monitoring device of claim 1, further comprising:

a further sensor configured to detect activity and/or posture of the patient; and

a memory to store at least one value indicative of the patient'"'"'s arterial blood pressure as determined by the arterial blood pressure monitor and a corresponding detected activity and/or posture of the patient as detected by the further sensor.

23. An implantable monitoring device to monitor a patient'"'"'s arterial blood pressure and configured to be implanted subcutaneously, the device comprising:

a housing;

subcutaneous (SubQ) electrodes configured to obtain a subcutaneous electrocardiogram (SubQ ECG) that is indicative of electrical activity of the patient'"'"'s heart, the subQ electrodes are attached to the housing;

a photoplethysmography (PPG) sensor configured to obtain a photoplethysmography (PPG) signal indicative of changes in the patient'"'"'s arterial blood volume, the PPG sensor comprising a light source and a light detector that are within, integral with or attached to the housing;

an arterial blood pressure monitor, within the housing, configured to

detect one or more predetermined feature of the SubQ ECG signal,

detect one or more predetermined feature of the PPG signal, and

determine at least one value indicative of the patient'"'"'s arterial blood pressure based on at least one said detected predetermined feature of the SubQ ECG and at least one said detected predetermined feature of the plethysmography signal;

wherein the implantable monitoring device is configured to transfer the at least one value indicative of the patient'"'"'s arterial blood pressure to an non-implanted device;

wherein the implantable monitoring device is not configured to pace the patient'"'"'s heart and not configured to defibrillate the patient'"'"'s heart; and

wherein the at least one value indicative of the patient'"'"'s arterial blood pressure is/are indicative of diastolic pressure (DP), systolic pressure (SP), pulse pressure (PP), mean arterial pressure (MAP), a change in DP, a change in SP, a change in PP and/or a change in MAP.

24. A non-implantable monitoring device to monitor a patient'"'"'s arterial blood pressure, the device comprising:

surface electrodes configured to obtain a surface electrocardiogram (ECG) that is indicative of electrical activity of the patient'"'"'s heart;

a non-implantable plethysmography sensor configured to obtain a plethysmography signal indicative of changes in the patient'"'"'s arterial blood volume;

an arterial blood pressure monitor configured to

detect one or more predetermined feature of the surface ECG signal,

detect one or more predetermined feature of the plethysmography signal, and

determine at least one value indicative of the patient'"'"'s arterial blood pressure based on at least one said detected predetermined feature of the surface ECG and at least one said detected predetermined feature of the plethysmography signal.

25. The non-implantable monitoring device of claim 24, further comprising

a housing within which the arterial blood pressure monitor is located;

wherein the surface electrodes are substantially flush with and/or adjacent to the housing;

wherein the plethysmography sensor comprises a photoplethysmography (PPG) sensor configured to obtain a photoplethysmography (PPG) signal indicative of changes in arterial blood volume; and

wherein the PPG sensor comprises a light source and a light detector that are within, integral with or attached to the housing.

26. The non-implantable monitoring device of claim 24, further comprising

a housing within which the arterial blood pressure monitor is located;

wherein the surface electrodes are remote from the housing and at least some of the surface electrodes are configured to be mounted on skin outside of a patient'"'"'s rib cage.

wherein the plethysmography sensor comprises a photoplethysmography (PPG) sensor configured to obtain a photoplethysmography (PPG) signal indicative of changes in arterial blood volume; and

wherein the PPG sensor comprises a light source and a light detector that are remote from the housing.