Heart data monitoring method and apparatus

• US 4,958,641 A
• Filed: 03/10/1989
• Issued: 09/25/1990
• Est. Priority Date: 03/10/1989
• Status: Expired due to Term

• Current Assignee: Card Guard Technologies Inc., Instromedix, Inc. (Koninklijke Philips N.V.)
• Original Assignee: Instromedix, Inc. (Koninklijke Philips N.V.)
• Inventors: Homayoun, Habib, Digby, Dennis
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/321,736
• Time in Patent Office: 564 Days
• Field of Search: 128/696, 128/702, 128/703, 128/903, 128/904, 128/704, 128/705, 128/706, 128/709, 128/710, 419/85
• US Class Current: 600/515
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening

Abstract

Improved ambulatory heart data monitoring and recording apparatus and method are described. The apparatus provides a power partitioning and management circuit that enables the extended, continuous ECG monitoring of an ambulatory patient'"'"'s cardiovascular performance and selective recording of arrhythmic events that transpire during such extended monitoring, wherein the circuit supplies reduced, unregulated DC power to potentially volatile data storage circuit elements in the event of the failure of the primary DC power source. An improved method validates QRS complexes by determining, during a learning period, characteristic criteria of the individual patient'"'"'s QRS waveform most representative of a valid QRS complex as opposed to motion or other artifacts, and thereafter uses such learned criteria in heart rate monitoring. In another improved method, the occurrence of an arrhythmic event is determined by monitoring not only the patient'"'"'s average heart rate relative to predetermined physiological norms but also the rate of change of the average heart rate, thereby reducing the likelihood that the apparatus gives false positive indications of abnormality.

Claims

1. For use in ECG monitoring apparatus, a patient-adaptive QRS complex validation method comprising:

characterizing a patient'"'"'s ECG pattern by sampling at the beginning and the end of plural sampling intervals between predefined analysis points an ECG signal for a predefined learning period of time and calculating a learned rate of change of such ECG signal over said intervals, and thereafter

determining the validity of QRS complexes by sampling between such analysis points such ECG signal, calculating a measured rate of change of such ECG signal and comparing said measured rate of change with said learned rate of change.

2. A patient-adaptive ECG monitoring method comprising:

sampling an ECG signal to produce data representing the ECG signal amplitudes at the beginning and the end of a sampling interval between predefined analysis points;

calculating the magnitude and the direction of the change in the signal amplitude over said interval, said magnitude of the change being equivalent to the magnitude result of subtracting the signal amplitude at the beginning of said interval from the signal amplitude at the end of said interval and said direction of the change being equivalent to the sign result of such subtracting;

repeating the sampling and calculating steps for a predefined learning period of time including plural ones of said intervals;

comparing the magnitudes of the changes in the ECG signal amplitude to determine the magnitude and the direction of the greatest change in ECG signal amplitude over said learning period; and

thereafter

identifying QRS complexes within such ECG signal by comparing with the magnitude of said greatest change the magnitudes of only those changes in the ECG signal amplitude which are of the same direction as the direction of said greatest change.

3. For use in ambulatory ECG monitoring apparatus, an arrhythmia identification method comprising:

detecting a patient'"'"'s heart beats;

calculating plural running heart rate averages;

constant threshold value to produce a first comparison result;

comparing said averages with one another to produce a second comparison result representing a rate of change of said averages; and

evaluating said first comparison result and said second comparison result, in accordance with predefined criteria, to identify arrhythmia.

4. For use in ambulatory ECG monitoring apparatus, an arrhythmia identification method comprising:

detecting a patient'"'"'s heart beats;

calculating plural running heart rate averages, each of said averages being based upon a first predefined number of detected heart beats;

first comparing said averages with at least one of a predefined maximum value and a predefined minimum value;

determining a rate of change of said averages over a second predefined number of detected heart beats;

second comparing said rate of change with a predefined threshold value; and

identifying arrhythmia based upon one of said averages being greater than said predefined maximum or less than said predefined minimum value and said rate of change being greater than said predefined threshold value.

5. The method of claim 4, wherein said determining and said second comparing steps are performed by the pair-wise comparison of at least two of said averages.

6. The method of claim 5, wherein said averages are stored in a queue of predefined depth, said queue being pushed with successive ones of said averages, wherein said pair-wise comparison is performed by determining whether at least one of said averages is within a predefined percentage of at least one other of said averages.