ACUTE ISCHEMIA DETECTION BASED ON PARAMETER VALUE RANGE ANALYSIS

• US 20130184597A1
• Filed: 03/07/2013
• Published: 07/18/2013
• Est. Priority Date: 08/25/2010
• Status: Active Grant

• Current Assignee: Angel Medical Systems, Inc.
• Original Assignee: Angel Medical Systems, Inc.
• Inventors: HOPENFELD, BRUCE
• Granted Patent: US 8,682,422 B2
• Time in Patent Office: Days
• US Class Current: 600/508
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• 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 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 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

Abstract

A heart monitor is disclosed. The monitor computes ST segment deviations and stores the results in heart rate based histograms. Periodically, the monitor analyzes the histogram data to determine a normal range of ST deviation for a particular heart rate range. The monitor computes heart rate dependent ischemia detection thresholds based on the upper and lower boundaries of the normal range.

Claims

1. A cardiac monitor comprising:

(a) a sensor adapted to sense an analog signal from a heart;

(b) a device coupled to the sensor, the device having an analog-to-digital circuit system contained therein for digitizing the analog signal to produce a digitized waveform;

(c) a processor electrically coupled to the analog-to-digital circuit system, said processor configured to;

(i) compute a plurality of ST deviations from the digitized waveform, the plurality of ST deviations being characterized by a statistical distribution characterized by an upper boundary and a lower boundary, the lower boundary being characterized by a boundary value;

(ii) storing data pertaining to the plurality of ST deviations in a form that enables characteristics of the statistical distribution to be computed;

(iii) form a lower detection threshold that depends on the difference between the boundary value and a preset value;

(iv) compute a subsequent ST deviation from the digitized waveform;

(v) apply a test to detect a cardiac event, wherein the test is based on the subsequent ST deviation and the lower detection threshold.

2. The system of claim 1 wherein the lower detection threshold is equal to a first function or a second function depending on whether the difference between the boundary value and the preset value exceeds a specified threshold.

3. The system of claim 2 wherein the second function is equal to the first function or a third function, whichever results in a lower detection threshold closer to the boundary value.

4. The system of claim 3 wherein the third function is equal to the sum of a preset value and the boundary value.

5. The system of claim 2 wherein the statistical distribution is characterized by a dispersion, and wherein the first function is equal to a specified distance from the boundary value, wherein the specified distance is based on the dispersion.

6. The system of claim 1 wherein the preset value corresponds to a change in polarity of ST deviation.