Means and method for the detection of cardiac events

• US 20070293775A1
• Filed: 06/22/2007
• Published: 12/20/2007
• Est. Priority Date: 05/26/2004
• Status: Abandoned Application

• Current Assignee: Angel Medical Systems, Inc.
• Original Assignee: Angel Medical Systems, Inc.
• Inventors: Johnson, Steven, Harwood, Jonathan, Fischell, Tim, Fischell, David, Fischell, Robert
• Application Number:
  US11/812,819
• Publication Number:
  US 20070293775A1
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02455 provided with high/low alarm devices
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/333 Recording apparatus specially adapted therefor
• 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 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• 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: 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 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/37258 Alerting the patient
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators
• CPC Class Codes: G16H 40/67 for remote operation

Abstract

Disclosed is a system for the detection of cardiac events that includes an implanted device called a cardiosaver, a physician'"'"'s programmer and an external alarm system. The system is designed to provide early detection of cardiac events such as acute myocardial infarction or exercise induced myocardial ischemia caused by an increased heart rate or exertion. The system can also alert the patient with a less urgent alarm if a heart arrhythmia is detected. Using different algorithms, the cardiosaver can detect a change in the patient'"'"'s electrogram that is indicative of a cardiac event within five minutes after it occurs and then automatically warn the patient that the event is occurring. To provide this warning, the system includes an internal alarm sub-system (internal alarm means) within the cardiosaver and/or an external alarm system (external alarm means) which are activated after the ST segment of the electrogram exceeds a preset threshold.

Claims

1. A system for detecting a cardiac event in a human patient the system including:

at least two implanted electrodes for sensing the electrogram signal from the patient'"'"'s heart;

an implanted device designed to store the electrogram signal from the patient'"'"'s heart, the implanted device being further designed to detect an ischemic event when the magnitude of a voltage change of the ST segment of the electrogram signal exceeds a detection threshold; and

means to process the stored electrogram signal to calculate the detection threshold.

2. The system of claim 1 further including a programmer, the programmer providing the means to process the stored electrogram signal to calculate the detection threshold.

3. The system of claim 2 where the detection threshold is set to be the mean value of the ST segment voltage plus a multiple of the standard deviation of the ST segment voltage for all the stored electrograms beats.

4. The system of claim 1 where the detection threshold is calculated for each of at least two different heart rate ranges.

5. The system of claim 1 further including patient alerting means.

6. The system of claim 5 where the patient alerting means includes at least two types of alarm signals.

7. The system of claim 6 where the patient alerting means is provided by the implanted device.

8. The system of claim 7 where the patient alerting means is provided by an external alarm system.

9. The system of claim 1 where the ischemic event is an acute myocardial infarction.

10. The system of claim 9 where the ischemic event is ST elevation acute myocardial infarction.

11. The system of claim 9 where the ischemic event is non-ST elevation acute myocardial infarction.

12. The system of claim 1 where the ischemic event is an ST shift at an elevated heart rate.

13. The system of claim 1 where the ischemic event is ST depression at an elevated heart rate.