System for continuous cardiac pathology detection and characterization
A system determines fractal values, a nonlinear fractal ratio and fractal data patterns in a heart and maps determined fractal values to medical conditions. A system for heart performance characterization and abnormality detection includes an interface for receiving sampled data representing an electrical signal indicating electrical activity of a patient heart over at least one heart beat cycle. A signal processor calculates, a first signal characteristic value comprising a first fractal dimension value derived from the sampled data over at least a portion of a heart beat cycle, a second signal characteristic value representing a computed derivative of the first fractal dimension value and a ratio of the first and second signal characteristic values. A comparator compares the calculated ratio with a threshold value to provide a comparison indicator. A patient monitor, in response to the comparison indicator indicating the calculated signal characteristic value exceeds the threshold value, generates an alert message associated with the threshold.
1. A system for heart performance characterization and abnormality detection, comprising:
an interface for receiving sampled data representing an electrical signal indicating electrical activity of a patient heart over at least one heart beat cycle;
a signal processor for calculating,
a first signal characteristic value comprising a first fractal dimension value derived from said sampled data over at least a portion of a heart beat cycle,
a second signal characteristic value representing a computed derivative of said first fractal dimension value and
a ratio of the first and second signal characteristic values;
a comparator for comparing the calculated ratio with a threshold value to provide a comparison indicator; and
a patient monitor for in response to said comparison indicator indicating the calculated signal characteristic value exceeds the threshold value, generating an alert message associated with the threshold.
2. A system according to claim 1 , wherein
said patient monitor, in response to said comparison indicator indicating the calculated signal characteristic value lies in a predetermined value range, generates an alert message associated with the value range.
3. A system according to claim 2 , wherein
said patient monitor substantially continuously monitors said comparison indicator for at least a 24 hour period.
4. A system according to claim 1 , wherein
said threshold value is derived from recorded electrical signal data for said patient.
5. A system according to claim 1 , wherein
said threshold value is derived from recorded electrical signal data for a population of patients.
6. A system according to claim 5 , wherein
said population of patients has similar demographic characteristics including at least two of, (a) age, (b) weight, (c) gender and (d) height, to those of said patient.
7. A system according to claim 1 , wherein
said signal processor dynamically adjusts said threshold value in response to a determined sensitivity of arrhythmia detection.
8. A system according to claim 1 , wherein
said signal processor calculates said ratio for a predetermined portion of a heart beat cycle in response to a synchronization signal.
9. A system according to claim 8 , wherein
said predetermined portion of said heart beat cycle includes an ST segment.
10. A system according to claim 1 , wherein
said signal processor calculates at least one of the first and second signal characteristic values as an averaged value over a plurality of heart beat cycles.
11. A system according to claim 1 , wherein
said signal processor calculates the first and second signal characteristic values in response to a heart rate synchronization signal.
12. A system according to claim 1 , including
a repository of mapping information, associating ranges of the ratio with corresponding medical conditions and
said comparator compares the ratio with said ranges to provide a comparison indicator identifying a medical condition and
said patient monitor generates an alert message identifying said medical condition.
13. A system according to claim 12 , wherein
said predetermined mapping information associates ranges of the ratio with particular patient demographic characteristics and with corresponding medical conditions and said system uses patient demographic data including at least one of, age weight, gender and height in comparing the ratio with said ranges and generating an alert message indicating a potential medical condition.
14. A system according to claim 1 , wherein
said interface provides a digitized electrical signal and
said signal processor calculates the first and second signal characteristic values of the digitized electrical signal.
15. A system according to claim 1 , wherein
said signal processor calculates said first fractal dimension value D as,
D
=
Log
(
N
(
s
)
)
Log
(
1
s
)
where, D is fractal dimension value of sampled data series X; s is a measure of a reconstructed sub data series X(m) (the measure can be length in one dimension data series, square number in two dimension data matrix series), N(s) is the number of the reconstructed sub data series.
16. A system according to claim 1 , wherein
said signal processor calculates first and second signal characteristic values for a first and different second portion of a single heart cycle respectively and
said signal processor calculates a ratio of the first and second signal characteristic values for the first and different second portion of the single heart cycle.
17. A system according to claim 16 , wherein
the first and different second portion of the single heart cycle correspond to repolarization and depolarization segments respectively.
18. A system according to claim 1 , wherein
said signal processor calculates signal characteristic values for the same portion of different first and second heart cycles.
19. A system according to claim 18 , wherein
said signal processor calculates a ratio of the signal characteristic values for the same portion of different first and second heart cycles.
20. A system for heart performance characterization and abnormality detection, comprising:
an interface for receiving sampled data representing frequency content of an electrical signal indicating electrical activity of a patient heart over at least one heart beat cycle;
a signal processor for calculating,
a first signal characteristic value comprising a first fractal dimension value derived from said sampled data over at least a portion of a heart beat cycle,
a second signal characteristic value representing a computed derivative of said first fractal dimension value and
a ratio of the first and second signal characteristic values;
a comparator for comparing the calculated ratio with a threshold value to provide a comparison indicator; and
a patient monitor for in response to said comparison indicator indicating the calculated signal characteristic value exceeds the threshold value, generating an alert message associated with the threshold.
21. A system for heart performance characterization and abnormality detection, comprising:
an interface for receiving sampled data representing composite time and frequency content of an electrical signal indicating electrical activity of a patient heart over at least one heart beat cycle;
a signal processor for calculating,
a first signal characteristic value comprising a first fractal dimension value derived from said sampled data over at least a portion of a heart beat cycle,
a second signal characteristic value representing a computed derivative of said first fractal dimension value and
a ratio of the first and second signal characteristic values;
a comparator for comparing the calculated ratio with a threshold value to provide a comparison indicator; and
a patient monitor for in response to said comparison indicator indicating the calculated signal characteristic value exceeds the threshold value, generating an alert message associated with the threshold.
22. A method for heart performance characterization and abnormality detection, comprising the activities of:
receiving sampled data representing an electrical signal indicating electrical activity of a patient heart over at least one heart beat cycle;
calculating,
a first signal characteristic value comprising a first fractal dimension value derived from said sampled data over at least a portion of a heart beat cycle,
a second signal characteristic value representing a computed derivative of said first fractal dimension value and
a ratio of the first and second signal characteristic values;
comparing the calculated ratio with a threshold value to provide a comparison indicator; and
in response to said comparison indicator indicating the calculated signal characteristic value exceeds the threshold value, generating an alert message associated with the threshold.