Locating J-points in electrocardiogram signals

1. A method for locating a J-point in a cardiac cycle waveform, the method being implemented by one or more data processors forming part of at least one computing device, the method comprising:

receiving electrocardiogram (ECG) data derived from an ECG electrode set affixed to a patient, the ECG data comprising a sequence of cardiac cycle waveforms that each correspond to a single cardiac cycle, each waveform comprising a series of samples;

locating, for each cardiac cycle waveform, an R-peak, an S-peak, and a T-peak;

calculating, for each cardiac cycle waveform, a Euclidian distance between the R-Peak and each of a plurality of samples within a window of samples;

locating a J-point for each cardiac cycle waveform by identifying, as a location of the J-point in the cardiac cycle waveform, a sample from among the plurality of samples having the shortest Euclidian distance to the R-peak; and

determining a physical state of the patient based on the J-point located in at least one cardiac cycle waveform.

2. The method of claim 1 , further comprising:

calculating, for each cardiac cycle waveform, a midpoint sample between the S-peak and the T-peak;

wherein the window only includes samples between the S-peak and the midpoint sample.

3. The method of claim 1 , further comprising:

identifying, for each cardiac cycle waveform, beginning of a T wave corresponding to the T-peak; and

measuring, for each cardiac cycle waveform, a deviation of an ST segment starting at the J-point and terminating at the beginning of the T wave relative to a baseline, the ST segment corresponding to an interval between ventricular depolarization and repolarization of the patient.

4. The method of claim 3 , wherein the baseline is a PR interval of the corresponding cardiac cycle waveform defined by an end of a P wave and start of a QRS complex in the cardiac cycle waveform.

5. The method of claim 3 , further comprising:

providing data characterizing the measured deviation of the ST segment.

6. The method of claim 5 , wherein providing data characterizing the measured deviation of the ST segment comprises at least one of: displaying at least a portion of the data on an electronic display, loading at least a portion of the data into memory, storing at least a portion of the data into persistent storage, or transmitting at least a portion of the data to a remote computing system.

7. The method of claim 3 , wherein the measured deviation is an elevation of the ST segment relative to the baseline or a depression of the ST segment relative to the baseline.

8. The method of claim 1 further comprising:

scaling, prior to the calculating, each cardiac cycle waveform to a predetermined scale.

9. The method of claim 8 , wherein each cardiac cycle waveform is scaled such that, on an x-axis of the cardiac cycle waveform, the scaling is between the R-peak and a midpoint sample between the S-peak and the T-peak and, on a y-axis of the cardiac cycle waveform, the scaling is between.

10. The method of claim 1 , further comprising:

providing, for each cardiac cycle waveform, data specifying the location of the identified J-point for the cardiac cycle waveform,

wherein the providing data comprises at least one of:

displaying at least a portion of the data on an electronic display, loading at least a portion of the data into memory, storing at least a portion of the data into persistent storage, or transmitting at least a portion of the data to a remote computing system.

11. The method of claim 1 , wherein at least one of the receiving, the locating the R-peak, the S-peak, and the T-peak, the calculating, the locating the J-point, and the determining is executed by a patient monitor in communication with the ECG electrode set.

12. The method of claim 1 , wherein the ECG data is continuously updated while the patient is being monitored.

13. The method of claim 1 , wherein in the calculating, the Euclidian distance between the R-Peak and each of the plurality of samples is calculated using the following equation:

d =√{square root over (( x 2 −x 1 ) 2 ++( y 2 −y 1 ) 2 )}

where d is the Euclidian distance,

(x 1 ,y 1 ) are coordinates of the R-peak, and

(x 2 , y 2 ) are coordinates of the sample.

14. A system for locating a J-point in a cardiac cycle waveform, the system comprising:

at least one data processor; and

memory storing instructions which, when executed by the at least one data processor, perform operations comprising:

receiving electrocardiogram (ECG) data derived from an ECG electrode set affixed to a patient, the ECG data comprising a sequence of cardiac cycle waveforms that each correspond to a single cardiac cycle, each waveform comprising a series of samples;

locating, for each cardiac cycle waveform, an R-peak, an S-peak, and a T-peak;

calculating, for each cardiac cycle waveform, a Euclidian distance between the R-Peak and each of a plurality of samples within a window of samples;

locating a J-point for each cardiac cycle waveform by identifying, as a location of the J-point in the cardiac cycle waveform, a sample from among the plurality of samples having the shortest Euclidian distance to the R-peak; and

determining a physical state of the patient based on the J-point located in at least one cardiac cycle waveform.

15. The system of claim 14 further comprising:

an electrocardiogram (ECG) electrode set for generating ECG signals when affixed to a patient.

16. The system of claim 15 , wherein the at least one data processor and memory form part of a patient monitor, the patient monitor comprising an interface for communication with the ECG electrode set.

17. A non-transitory computer program product storing instructions which, when executed by at least one data processor forming part of at least one computing device, perform operations for locating a J-point in a cardiac cycle waveform, the operations comprising:

receiving electrocardiogram (ECG) data derived from an ECG electrode set affixed to a patient, the ECG data comprising a sequence of cardiac cycle waveforms that each correspond to a single cardiac cycle, each waveform comprising a series of samples;

locating, for each cardiac cycle waveform, an R-peak, an S-peak, and a T-peak;

calculating, for each cardiac cycle waveform, a Euclidian distance between the R-Peak and each of a plurality of samples within a window of samples;

locating a J-point for each cardiac cycle waveform by identifying, as a location of the J-point in the cardiac cycle waveform, a sample from among the plurality of samples having the shortest Euclidian distance to the R-peak; and

determining a physical state of the patient based on the J-point located in at least one cardiac cycle waveform.