RR interval monitoring method and blood pressure cuff utilizing same

• US 8,417,326 B2
• Filed: 08/04/2008
• Issued: 04/09/2013
• Est. Priority Date: 08/02/2007
• Status: Active Grant

• Current Assignee: The Research Foundation for The State University of New York (State University of New York)
• Original Assignee: The Research Foundation for The State University of New York (State University of New York)
• Inventors: Raeder, Ernst A., Chon, Ki
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): WU, EUGENE T
• Application Number:
  US12/671,847
• Publication Number:
  US 20110166466A1
• Time in Patent Office: 1,709 Days
• Field of Search: 600/508, 600/509, 600/515, 600/516, 600/518, 600/519
• US Class Current: 600/518
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/346 Analysis of electrocardiograms
• 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 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 8/02 Measuring pulse or heart rate
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: A61B 8/5269 involving detection or reduction of artifacts for image enhancement algorithms G06T5/00

Abstract

Disclosed is an apparatus and method for ambulatory, real-time detection of Atrial Fibrillation (AF) providing an overall accuracy that refers to detection of AF, irrespective of the duration of AF and beat-to-beat classification.

Claims

1. An Atrial Fibrillation (AF) analysis method comprising:

obtaining an output that includes a heart beat;

deriving a heart beat interval;

analyzing a number (N) of heart beat intervals from the output; and

detecting a likelihood of AF by;

calculating a Turning Points Ratio (TPR) of the N heart beat intervals;

calculating a root mean square of successive (RMSSD) heart beat intervals; and

calculating Shannon Entropy (SE) of the N heart beat intervals.

2. The method of claim 1, further comprising determining whether the RMSSD is greater than a RMSSD threshold.

3. The method of claim 2, wherein the RMSSD threshold is a percentage of a mean heart beat interval of a beat segment of the N intervals.

4. The method of claim 1, further comprising determining whether the SE is greater than an SE threshold.

5. The method of claim 1, further comprising determining if the calculated TPR meets a randomness criteria.

6. The method of claim 1, further comprising:

calculating autocorrelation coefficients at time delays (a) and (b);

determining a difference there between and comparing the difference to a threshold; and

detecting an AF upon finding the difference to exceed the threshold, thereby obtaining improved specificity and sensitivity of AF identification.

7. The method of claim 6, wherein time delay a=0 interval and b=1 interval and the autocorrelation coefficients at delay 0 are normalized to 1.

8. The method of claim 7, wherein the analysis is repeated until the end of the output is reached.

9. The method of claim 1, wherein calculation of the TPR, of the RMSSD, and of the SE is performed in varied order.

10. The method of claim 1, further comprising elimination of ectopic beats and a plurality of compensatory pauses.

11. The method of claim 10, wherein the plurality of compensatory pauses are associated with each ectopic beat.

12. The method of claim 1, wherein the heart beat interval is derived between select peaks in the output.

13. The method of claim 1, wherein the output is obtained from one of an ECG, a piezoelectric sensor, continuous blood pressure monitoring and pulse oximeter data.

14. The method of claim 1, wherein the output is obtained in real time.

15. An apparatus for Atrial Fibrillation (AF) detection, the apparatus comprising:

a sensor for obtaining an output that includes a heart beat; and

a processor for deriving a heart beat interval from the output, and analyzing a number (N) of heart beat intervals from the output, wherein the processor is configured to detect a likelihood of AF by;

calculating a Turning Points Ratio (TPR) of the N heart beat intervals,

calculating a root mean square of successive (RMSSD) heart beat intervals, and

calculating Shannon Entropy (SE) of the N heart beat intervals.