System for detection of different types of cardiac events

• US 20070093720A1
• Filed: 11/09/2006
• Published: 04/26/2007
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: Angel Medical Systems, Inc.
• Original Assignee: Angel Medical Systems, Inc.
• Inventors: Hopenfeld, Bruce, Johnson, Steven, Harwood, Jonathan, Fischell, Tim, John, Michael, Fischell, David, Fischell, Robert
• Granted Patent: US 8,630,702 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/36 Detecting PQ interval, PR interval or QT interval
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7465 Arrangements for interactive communication between patient and care services, e.g. by using a telephone network telemetry of measured physiological signal A61B5/0002
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

A system for the detection of cardiac events occurring in a human patient is provided. At least two electrodes are included in the system for obtaining an electrical signal from a patient'"'"'s heart. An electrical signal processor is electrically coupled to the electrodes for processing the electrical signal and a patient alarm means is further provided and electrically coupled to the electrical signal processor. The electrical signal is acquired in the form of electrogram segments, which are categorized according to heart rate, ST segment shift and type heart rhythm (normal or abnormal). Baseline electrogram segments are tracked over time.

Claims

1. A cardiac event detection system for detecting a cardiac event in a patient comprising:

(a) at least two electrodes for sensing an electrogram electrical signal from said patient'"'"'s heart;

(b) an implantable device coupled to said electrodes, said implantable device having an analog-to-digital circuit system contained therein for digitizing said electrogram electrical signal to produce electrogram segments;

(c) a processor contained in said implantable device and electrically coupled to said electrodes, said processor including means for determining whether an electrogram segment qualifies as a baseline segment, said processor further including means for tracking the failure of electrogram segments to qualify as baseline electrogram segments.

2. The system of claim 1 wherein the means for tracking includes means for determining whether no electrogram segments have qualified as a baseline electrogram segment over a baseline alert time period.

3. The system of claim 2 where implanted device includes patient alerting means which are activated following determination that no electrogram segments have qualified as a baseline electrogram segment over the baseline alert time period.

4. The system of claim 2 wherein the inability to collect a baseline electrogram segment is caused by the patient'"'"'s heart rate being higher than a preset normal heart rate range.

5. The system of claim 2 wherein the inability to collect a baseline electrogram segment is caused by the patient'"'"'s heart rate being lower than a preset normal heart rate range.

6. The system of claim 2 wherein the inability to collect a baseline electrogram segment is caused by the patient'"'"'s heart rate being irregular than a preset normal heart rate range.

7. The system of claim 2 wherein the inability to collect a baseline electrogram segment is caused by the patient'"'"'s electrogram segments having too many abnormal beats to qualify as a baseline electrogram segment.

8. The system of claim 2 wherein at least one of the electrodes is located within the heart.

9. The system of claim 8 wherein the electrode located within the heart is located within the right ventricle.

10. The system of claim 1 wherein at least one electrode is located subcutaneously.

11. A cardiac event detection system for detecting a cardiac event in a patient comprising:

(a) at least two electrodes for sensing an electrogram electrical signal from said patient'"'"'s heart;

(b) an implantable device coupled to said electrodes, said implantable device having an analog-to-digital circuit system contained therein for digitizing said electrogram electrical signal, thereby generating a digitized electrogram;

(c) a processor contained in said implantable device and electrically coupled to said electrodes, said processor including means for detecting ST segment shifted beats within the digitized electrogram and for computing the heart rate associated with various portions of the digitized electrogram, the processor further including means for detecting a cardiac event based upon both the duration of an ST shift and the heart rate.

12. The cardiac event detection system of claim 11 wherein the processor further including means for detecting the cardiac event based upon both the duration of an ST shift and a change in the heart rate.

13. The cardiac event detection system of claim 12 wherein the cardiac event is detected by comparing the ST shift of at least one heart beat with a heart rate dependent threshold.

14. The cardiac event detection system of claim 13 wherein the heart rate dependent threshold is selected based on a higher heart rate than the current heart rate when the higher heart rate occurred within a specified amount of time before a current heart beat was acquired.

15. The cardiac event detection system of claim 11 wherein electrogram segments are categorized according to ST shift and heart rate, and wherein the duration of an ST shift and the heart rate are determined based on the categorization of electrogram segments.

16. The cardiac event detection system of claim 11 wherein the cardiac event is detected based on an inverse relationship between heart rate and duration of an ST shift.

17. The cardiac event detection system of claim 16 wherein electrogram segments are categorized according to ST shift and heart rate, and wherein the duration of an ST shift and the heart rate are determined based on the categorization of electrogram segments, and wherein the inverse relationship between heart rate and duration of an ST shift is implemented by requiring a greater number of ST shifted electrogram segments at a higher heart rate category compared to a lower heart rate category.

18. A cardiac event detection system for detecting a cardiac event in a patient comprising:

(a) at least two electrodes for sensing an electrogram electrical signal from said patient'"'"'s heart;

(b) an implantable device coupled to said electrodes, said implantable device having an analog-to-digital circuit system contained therein for digitizing said electrogram electrical signal, thereby generating a digitized electrogram;

(c) a processor contained in said implantable device and electrically coupled to said electrodes, said processor including means for detecting ST segment shifted beats within the digitized electrogram and for computing the heart rate associated with various portions of the digitized electrogram, the processor further including means for detecting a cardiac event based upon both the duration of an ST shift and heart rate, wherein the duration of an ST shift that will trigger detection of a cardiac event varies according to the polarity of the ST shift.

19. The cardiac event detection system of claim 18 wherein the duration of an ST shift that will trigger detection of a cardiac event varies according to the heart rate associated with the ST shift.

20. The cardiac event detection system of claim 19 wherein a first electrode is implantable within the heart and a second electrode is implantable outside of the heart, and wherein a positive ST deviation is defined as the second electrode having a greater potential than the first electrode, and wherein an event is detected when:

(i) a positive ST shift at a normal heart rate range lasts at least A seconds, (ii) a positive ST shift at a high heart rate range lasts at least B seconds;

(iii) a negative ST shift at a normal heart rate range lasts at least C seconds, and (iv) a negative ST shift at a high heart rate range lasts at least D seconds, wherein A is less than C and B is less than D, and wherein A is less than B and C is less than D.