Methods and systems that monitor for an impending myocardial infarction

• US 9,022,945 B2
• Filed: 02/04/2014
• Issued: 05/05/2015
• Est. Priority Date: 07/08/2009
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Fayram, Timothy A., Dokko, Daniell, Farazi, Taraneh Ghaffari, Carlson, Mark
• Primary Examiner(s): Mallari, Patricia
• Assistant Examiner(s): WEARE, MEREDITH H
• Application Number:
  US14/172,776
• Publication Number:
  US 20140155707A1
• Time in Patent Office: 455 Days
• Field of Search: 600/481, 600507-509
• US Class Current: 600/507
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02154 by optical transmission
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• 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 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood

Abstract

Implantable systems, and methods for use therewith, are provided for monitoring for an impending myocardial infarction. A signal indicative of changes in arterial blood volume is obtained. Such a signal can be a photoplethysmography signal or an impedance plethysmography signal. For each of a plurality of periods of time, a metric indicative of the areas under the curve of the signal or number of inflections in the signal is determined. An impending myocardial infarction is monitored for based on changes in the metric indicative of the area under the curve of the signal or number of inflections in the signal, and an alert and/or therapy is triggered in response to an impending myocardial infarction being predicted.

Claims

1. For use with a chronically implanted device, a method for monitoring for an impending myocardial infarction (MI), comprising:

(a) obtaining

a first signal indicative of changes arterial volume, the first signal comprising one of a photoplethysmography (PPG) signal or an impedance-plethysmography (IPG) signal, and

a second signal indicative of electrical cardiac activity, the second signal comprising one of an electrocardiogram (ECG) signal or an intracardiac electrogram (IEGM) signal;

(b) determining, based on the first and second signals, a metric indicative of aortic pulse wave velocity (PWV);

(c) determining, based on the first signal, a metric indicative of diastolic blood pressure (DBP);

(d) determining, based on at least one of the first and or second signals, a metric indicative of heart rate (HR);

(e) determining, based on the first signal, a metric indicative of vascular stiffness (VS) by determining a measure of a number of inflections in the first signal, wherein a greater the measure of the number of inflections in the first signal a greater the vascular stiffness;

(f) monitoring for an impending MI based on the metrics indicative of PWV, DBP, HR and VS, wherein an increase in each of the metrics indicative of PWV, DBP, HR and VS is interpreted as an increase in a risk of an impending MI; and

(g) triggering an alert and/or therapy in response to an impending MI being detected at step (f);

wherein one or more of steps (b) through (g) is/are performed using a processor.

2. The method of claim 1, wherein step (f) comprises detecting an impending MI if the metrics indicative of PWV, DBP, HR and VS each satisfies a corresponding criteria indicative of an impending MI.

3. The method of claim 1, wherein step (f) comprises detecting an impending MI if a majority of the metrics indicative of PWV, DBP, HR and VS each satisfies a corresponding criteria indicative of an impending MI.

4. The method of claim 1, wherein:

the first signal indicative of changes arterial volume, that is obtained at step (a), is a photoplethysmography (PPG) signal; and

step (e) comprises determining, based on the PPG signal, a metric indicative of vascular stiffness (VS) by determining a measure of a number of inflections in the PPG signal, wherein a greater the measure of the number of inflections in the PPG signal a greater the vascular stiffness.

5. The method of claim 1, wherein:

the first signal indicative of changes arterial volume, that is obtained at step (a), is an impedance-plethysmography (IPG) signal; and

step (e) comprises determining, based on the IPG signal, a metric indicative of vascular stiffness (VS) by determining a measure of a number of inflections in the IPG signal, wherein a greater the measure of the number of inflections in the IPG signal a greater the vascular stiffness.

6. A system for monitoring for an impending myocardial infarction (MI), comprising:

a sensor configured to produce a first signal that is indicative of changes in arterial volume;

one or more electrodes to produce a second signal indicative of electrical cardiac activity, the second signal comprising one of an electrocardiogram (ECG) signal or an intracardiac electrogram (IEGM) signal; and

a monitor configured to

determine, based on the first and second signals, a metric indicative of aortic pulse wave velocity (PWV);

determine, based on the first signal, a metric indicative of diastolic blood pressure (DBP);

determine, based on at least one of the first and second signals, a metric indicative of heart rate (HR);

determine, based on the first signal, a metric indicative of vascular stiffness (VS) by determining a measure of a number of inflections in the first signal, wherein a greater the measure of the number of inflections in the first signal a greater the vascular stiffness;

monitor for an impending MI based on the metrics indicative of PWV, DBP, HR and VS, wherein an increase in each of the metrics indicative of PWV, DBP, HR and VS is interpreted as an increase in a risk of an impending MI; and

trigger an alert and/or therapy in response to an impending MI being detected.

7. The system of claim 6, wherein the monitor is configured to detect an impending MI if the metrics indicative of PWV, DBP, HR and VS each satisfies a corresponding criteria indicative of an impending MI.

8. The system of claim 6, wherein the monitor is configured to detect an impending MI if a majority of the metrics indicative of PWV, DBP, HR and VS each satisfies a corresponding criteria indicative of an impending MI.

9. The system of claim 6, wherein:

the first signal indicative of changes arterial volume, that is obtained by the sensor, is a photoplethysmography (PPG) signal; and

the monitor is configured to determine, based on the PPG signal, a metric indicative of vascular stiffness (VS) by determining a measure of a number of inflections in the PPG signal, wherein a greater the measure of the number of inflections in the PPG signal a greater the vascular stiffness.

10. The system of claim 6, wherein:

the first signal indicative of changes arterial volume, that is obtained by the sensor, is an impedance-plethysmography (IPG) signal; and

the monitor is configured to determine, based on the IPG signal, a metric indicative of vascular stiffness (VS) by determining a measure of a number of inflections in the IPG signal, wherein a greater the measure of the number of inflections in the IPG signal a greater the vascular stiffness.