Methods and systems for characterizing the quality of an electrocardiogram signal
Described here are methods, devices and systems for characterizing a physiological signal such as an electrocardiogram (ECG) signal. Generally, the method includes receiving the ECG signal generated by an ECG device coupled to a patient. ECG signal quality for a plurality of consecutive beats may be determined based on a dispersion coefficient and a deviation from an average of each of a plurality of ECG parameters. Indexing information may be generated for set of sequences from the plurality of consecutive cardiac beats. Each of the sequences may comprise a first predetermined number of consecutive cardiac beats. The set of the sequences may be ordered based upon the ECG signal quality.
1. A method comprising:
receiving an ECG signal generated by an ECG device coupled to a subject, the ECG signal comprising a plurality of consecutive cardiac beats;
determining ECG signal quality of the plurality of consecutive cardiac beats based on a dispersion coefficient and a deviation from an average of each of a plurality of ECG parameters; and
generating indexing information for a set of sequences from the plurality of consecutive cardiac beats, wherein each sequence of the set of sequences comprises a first predetermined number of consecutive cardiac beats, wherein the set of sequences are ordered based upon the ECG signal quality; and
determining subject participation in a study using the indexing information, wherein the subject participation comprises exclusion from the study when a QT evaluation comprises a QTc in excess of 450 milliseconds.
2. The method of claim 1 , wherein the ECG signal comprises an epoch comprising a second predetermined number of consecutive cardiac beats.
3. The method of claim 2 , wherein the ECG signal quality is determined for each sequence of the set of sequences.
4. The method of claim 3 , wherein the deviation from the average of each of the plurality of ECG parameters comprises a sum of differences for a sequence and its average from the epoch for each of the plurality of ECG parameters.
5. The method of claim 4 , wherein the ECG signal quality is Q=DP*(Σ ), where DP is the dispersion coefficient and x̆ is a deviation between a sequence and an average of an epoch for an ECG parameter.
6. The method of claim 5 , wherein the dispersion coefficient is based on a range and a normalized range for each of the plurality of ECG parameters.
7. The method of claim 6 , wherein the dispersion coefficient is an evenly weighted sum of the normalized range of the plurality of ECG parameters.
8. The method of claim 6 , wherein the range is Rep(x)=Max(x)−Min(x), where x comprises one of the ECG parameters.
9. The method of claim 8 , wherein the normalized range is
(
x
)
=
Rep
(
x
)
x
_
,
where x is an average value of one of the ECG parameters within the epoch.
10. The method of claim 1 , wherein the ECG parameters comprise QT, PR, and QRS.
11. The method of claim 2 , wherein the first predetermined number is two or more, and the second predetermined number is greater than the first predetermined number.
12. The method of claim 3 , further comprising ordering the set of sequences in ascending order based on the ECG signal quality.
13. The method of claim 12 , further comprising selecting a subset of the set of sequences ordered in ascending order based on the ECG signal quality for the QT evaluation using the indexing information, wherein the QT evaluation is associated with a new chemical entity.
14. The method of claim 13 , wherein the QT evaluation comprises one or more of a Thorough QT (TQT) study, phase I study, phase II study, and phase III study.
15. The method of claim 12 , further comprising selecting a subset of the set of sequences ordered in ascending order based on the ECG signal quality for one or more of QRS and PR evaluation associated with a new chemical entity using the indexing information.
16. The method of claim 1 , further comprising:
connecting the ECG device to the subject; and
disconnecting the ECG device from the subject;
wherein determining ECG signal quality of the plurality of consecutive cardiac beats is performed prior to disconnecting the ECG device from the subject.
17. The method of claim 16 , further comprising receiving a second ECG signal from the ECG device coupled to the subject if the ECG signal quality of the plurality of consecutive cardiac beats exceeds a predetermined threshold corresponding to one or more of the dispersion coefficient and the deviation from the average of each of the plurality of ECG parameters.
18. The method of claim 1 , further comprising extracting one or more segments of the ECG signal using the indexing information.