Systems and Methods for Use By an Implantable Medical Device for Detecting and Discriminating Stroke and Cardiac Ischemia Using Electrocardiac Signals and Hemodynamic Parameters

• US 20110224555A1
• Filed: 03/11/2010
• Published: 09/15/2011
• Est. Priority Date: 03/11/2010
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Park, Euljoon
• Granted Patent: US 8,467,864 B2
• Time in Patent Office: Days
• US Class Current: 600/483
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

Techniques are provided for detecting and distinguishing stroke and cardiac ischemia within a patient using an implantable medical device. In one example, a preliminary indication of stroke is detected by a pacemaker or similar implantable device based on an analysis of features of an intracardiac electrogram (IEGM) sensed by the device. Exemplary IEGM features indicative of possible stroke include the onset of prominent U-waves, the onset of notched T-waves, and changes in ST segment duration or QT duration. Upon detection of a possible stroke, the device then detects one or more hemodynamic parameters that are typically affected by cardiac ischemia. Such hemodynamic parameters can include, e.g., cardiac contractility or stroke volume. The device then distinguishes stroke and cardiac ischemia from one another based on whether any changes detected in the hemodynamic parameters are consistent with cardiac ischemia. Implantable systems that exploit subcutaneous electrocardiograms (ECGs) rather than IEGMs are also described.

Claims

1. A method for use with an implantable medical device for implant within a patient, said method comprising:

sensing electrocardiac signals within the patient indicative of a possible stroke;

detecting hemodynamic parameters within the patient affected by a possible cardiac ischemia; and

distinguishing stroke from cardiac ischemia within the patient based on the electrocardiac signals and the hemodynamic parameters.

2. The method of claim 1 further comprising detecting a preliminary indication of stroke within the patient based on predetermined changes in the electrocardiac signals indicative of possible stroke.

3. The method of claim 2 wherein detecting the preliminary indication of stroke comprises detecting one more of the onset of prominent U-waves, the onset of notched T-waves, changes in ST segment duration, and changes in QT duration.

4. The method of claim 3 wherein detecting the preliminary indication of stroke comprises detecting trends toward one more or more of increasingly prominent U-waves, increasingly notched T-waves, changing ST segment durations, and changing QT durations.

5. The method of claim 2 wherein detecting hemodynamic parameters within the patient is performed upon detection of the preliminary indication of stroke.

6. The method of claim 5 wherein distinguishing stroke from cardiac ischemia comprises:

examining the hemodynamic parameters for changes consistent with cardiac ischemia;

generating a signal indicative of stroke if the hemodynamic parameters are not consistent with cardiac ischemia; and

generating a signal indicative of cardiac ischemia if the hemodynamic parameters are indicative of cardiac ischemia.

7. The method of claim 6 wherein examining the hemodynamic parameters for changes consistent with cardiac ischemia comprises:

comparing a selected hemodynamic parameter against a corresponding baseline parameter previously detected within the patient during a time period without cardiac ischemia; and

determining that the selected hemodynamic parameter is consistent with cardiac ischemia if the parameter differs substantially from its baseline value.

8. The method of claim 7 wherein the selected hemodynamic parameter comprises one or more of a cardiac contractility parameter and a stroke volume parameter.

9. The method of claim 1 wherein sensing the electrocardiac signals comprises sensing signals representative of an intracardiac electrogram (IEGM).

10. The method of claim 9 wherein the implantable device comprises an implantable cardiac rhythm management device and wherein sensing the electrocardiac signals sensed is performed to sense signals representative of the IEGM using the implantable cardiac rhythm management device.

11. The method of claim 1 wherein sensing the electrocardiac signals comprises sensing signals representative of an electrocardiogram (ECG).

12. The method of claim 11 wherein the implantable device is a subcutaneously-implantable monitoring device and wherein sensing the electrocardiac signals is performed to sense signals representative of the ECG using the subcutaneously-implantable monitoring device.

13. A method for use with an implantable medical device for implant within a patient, said method comprising:

sensing electrocardiac signals using the implantable device;

detecting a preliminary indication of stroke within the patient based on predetermined changes in the electrocardiac signals indicative of possible stroke;

if a preliminary indication of stroke is detected, then sensing a hemodynamic parameter within the patient affected by cardiac ischemia and examining the hemodynamic parameter for changes consistent with cardiac ischemia;

confirming the stroke if changes in the hemodynamic parameter are not consistent with cardiac ischemia; and

disconfirming the stroke if changes in the hemodynamic parameter are consistent with cardiac ischemia.

14. A system for use with an implantable medical device for implant within a patient, said system comprising:

an electrocardiac signal sensor;

an hemodynamic parameter detector; and

a stroke/cardiac ischemia discrimination system configured to distinguish stroke from cardiac ischemia within the patient based on the electrocardiac signals and hemodynamic parameters.

15. The system of claim 14 wherein the electrocardiac signal sensor is operative to detect one more of the onset of prominent U-waves, the onset of notched T-waves, changes in ST segment duration, and changes in QT duration within electrocardiac signals.

16. The system of claim 14 wherein the hemodynamic parameter detector is operative to detect one more of cardiac contractility and stroke volume.

17. The system of claim 16 wherein the hemodynamic parameter detector comprises one or more of a pressure sensor, a cardiogenic impedance sensor and a photoplethysmography (PPG) sensor.

18. The system of claim 14 wherein the stroke/cardiac ischemia discrimination system is configured to:

detect a preliminary indication of stroke within the patient based on predetermined changes in the electrocardiac signals indicative of possible stroke;

if a preliminary indication of stroke is detected, then examine the hemodynamic parameter for changes consistent with cardiac ischemia;

confirm the stroke if changes in the hemodynamic parameter are not consistent with cardiac ischemia; and

disconfirm the stroke if changes in the hemodynamic parameter are consistent with cardiac ischemia.

19. A system for use with an implantable medical device for implant within a patient, said system comprising:

means for sensing electrocardiac signals within the patient indicative of a possible stroke;

means for sensing hemodynamic parameters within the patient; and

means for distinguishing stroke from cardiac ischemia based on the electrocardiac signals and the hemodynamic parameters.