Heart Rate Detection in High Noise Conditions

• US 20100094150A1
• Filed: 10/01/2009
• Published: 04/15/2010
• Est. Priority Date: 10/09/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ravindran, Sourabh
• Granted Patent: US 8,457,723 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 7/00 Instruments for auscultation

Abstract

A method of processing heart monitoring samples is provided that includes computing a folded correlation value for each heart monitoring sample in a plurality of heart monitoring samples and identifying peaks corresponding to heartbeats based on the folded correlation values of the heart monitoring samples.

Claims

1. A method of processing heart monitoring samples, the method comprising:

computing a folded correlation value for each heart monitoring sample in a plurality of heart monitoring samples; and

identifying peaks corresponding to heartbeats based on the folded correlation values of the heart monitoring samples.

2. The method of claim 1, further comprising:

computing a heart rate based on the identified peaks.

3. The method of claim 2, further comprising:

displaying the heart rate.

4. The method of claim 1, wherein computing a folded correlation value comprises:

selecting a first frame of N consecutive heart monitoring samples, wherein a first heart monitoring sample in the plurality of heart monitoring samples is a center heart monitoring sample in the first frame, and wherein N is an odd number; and

computing a folded correlation value for the first heart monitoring sample as a dot product of (N-1)/2 heart monitoring samples preceding the first heart monitoring sample in the first frame and time-reversed (N-1)/2 heart monitoring samples following the first heart monitoring sample in the first frame.

5. The method of claim 4, wherein computing a folded correlation value further comprises:

selecting a second frame of N consecutive heart monitoring samples, wherein a second heart monitoring sample adjacent to the first heart monitoring sample is a center heart monitoring sample in the second frame; and

computing a folded correlation value for the second heart monitoring sample as a dot product of (N-1)/2 heart monitoring samples preceding the second heart monitoring sample in the second frame and time-reversed (N-1)/2 heart monitoring samples following the second heart monitoring sample in the second frame.

6. The method of claim 4, wherein N is selected based on one selected from a group consisting of a length of a primary heart sound component S1 and a length of an R-wave.

7. The method of claim 1, further comprising:

receiving the plurality of heart monitoring samples from one selected from a group consisting of an audio sensor, an accelerometer, and a plurality of electrodes.

8. The method of claim 1, wherein an identified peak is one selected from a group consisting of an R-wave peak or an S1 peak.

9. A method of processing heart monitoring samples, the method comprising:

receiving a monitoring signal comprising the heart monitoring samples;

dividing the heart monitoring samples into overlapping frames of length N, wherein each frame overlaps a previous frame by N-1 heart monitoring samples and wherein N is an odd number;

folding heart monitoring samples in each frame around a center heart monitoring sample in the frame to generate a folded correlation value for the center heart monitoring sample; and

identifying peaks corresponding to heartbeats based on the folded correlation values.

10. The method of claim 9, further comprising:

computing a heart rate based on the identified peaks.

11. The method of claim 9, wherein folding heart monitoring samples comprises:

computing a dot product of a first vector consisting of (N-1)/2 heart monitoring samples preceding the center heart monitoring sample in a frame and a second vector consisting of (N-1)/2 heart monitoring samples following the center heart monitoring sample in the frame, wherein the heart monitoring samples in the first vector are in time order and the heart monitoring samples in the second vector are in reverse time order.

12. The method of claim 9, wherein the monitoring signal is received from one selected from a group consisting of an audio sensor, an accelerometer, and a plurality of electrodes.

13. The method of claim 9, wherein an identified peak is one selected from a group consisting of an R-wave peak or an S1 peak.

14. The method of claim 9, wherein N is selected based on one selected from a group consisting of a length of a primary heart sound component S1 and a length of an R-wave.

15. A system comprising:

a processor; and

a memory configured to store software instructions executable by the processor, wherein when executed by the processor, the software instructions cause the system to perform a method to process heart monitoring samples, the method comprising;

receiving a monitoring signal comprising the heart monitoring samples;

dividing the heart monitoring samples into overlapping frames of length N, wherein each frame overlaps a previous frame by N-1 heart monitoring samples and wherein N is an odd number;

folding heart monitoring samples in each frame around a center heart monitoring sample in the frame to generate a folded correlation value for the center heart monitoring sample; and

identifying peaks corresponding to heartbeats based on the folded correlation values.

16. The system of claim 15, wherein the method further comprises:

computing a heart rate based on the identified peaks.

17. The system of claim 15, wherein folding heart monitoring samples comprises:

computing a dot product of a first vector consisting of (N-1)/2 heart monitoring samples preceding the center heart monitoring sample in a frame and a second vector consisting of (N-1)/2 heart monitoring samples following the center heart monitoring sample in the frame, wherein the heart monitoring samples in the first vector are in time order and the heart monitoring samples in the second vector are in reverse time order.

18. The system of claim 15, wherein the monitoring signal is received from one selected from a group consisting of an audio sensor, an accelerometer, and a plurality of electrodes.

19. The system of claim 15, wherein an identified peak is one selected from a group consisting of an R-wave peak or an S1 peak.

20. The system of claim 15, wherein N is selected based on one selected from a group consisting of a length of a primary heart sound component S1 and a length of an R-wave.