System for cardiac impairment detection based on signal regularity
A system for heart performance characterization and abnormality detection comprises an input processor and a signal processor. The input processor receives first sampled data representing a first signal portion of a heart activity related signal and second sampled data representing a second signal portion of a heart activity related signal. The signal processor determines distribution data associated with degree of similarity between the first and second signal portions by determining a difference between (a) values derived by applying a first function to mean adjusted sampled values of the first signal portion and (b) values derived by applying a second function to mean adjusted sampled values of the second signal portion. In response to the determined distribution data, the signal processor initiates generation of a message associated with the degree of similarity between the first and second signal portions.
1. A system for heart performance characterization and abnormality detection, comprising:
an input processor for receiving,
first sampled data representing a first signal portion of a heart electrical activity related signal and
second sampled data representing a second signal portion different to said first signal portion of the heart electrical activity related signal; and
a signal processor for,
determining distribution data associated with degree of similarity between the first and second signal portions by determining a difference between
(a) values derived by applying a first function to mean adjusted sampled values of the first signal portion and
(b) values derived by applying a second function to mean adjusted sampled values of the second signal portion and
in response to the distribution data, initiating generation of a message associated with said degree of similarity between the first and second signal portions;
wherein said signal processor derives a regularity value by summing a plurality of values individually comprising a product of a determined distribution data value and a logarithm of said distribution data value.
2. A system according to claim 1 , wherein
said first function and said second function comprise probability density functions.
3. A system according to claim 1 , wherein
said mean adjusted sampled values of the first signal portion are derived by taking a difference between individual sampled values of said first signal portion and an average of said sampled values of said first signal portion and
said mean adjusted sampled values of the second signal portion are derived by taking a difference between individual sampled values of said second signal portion and an average of said sampled values of said second signal portion.
4. A system according to claim 1 , wherein
said first function and said second function comprise Gaussian functions.
5. A system according to claim 1 , wherein
said first function and said second function comprise at least one of, (a) frequency spectrum functions and (b) statistical functions.
6. A system according to claim 1 , wherein
said signal processor determines said distribution data using a function of a form,
p RT-P ( x )= p RT ( x−μ RT )− p p ( x−μ p )
where, x is a data point in a distribution, p(•) is a distribution probability function, p RT (•) and p p (•) are a statistical distribution for an RT portion and P wave portion of a signal respectively and μ RT and μ p are mean values of the RT portion and P wave portion sampled data, respectively.
7. A system according to claim 1 , wherein
said signal processor derives said regularity value using a function of a form,
μ
RT
-
μ
P
δ
RT
-
δ
P
·
[
-
∑
x
∈
Ω
p
RT
-
P
(
x
)
·
log
p
RT
-
P
(
x
)
]
where μ RT and μ p are a mean value of RT and P wave signal portions, δ RT and δ P are standard deviations of the RT and P wave signal portions; p RT-P (x) is calculated distribution data; Ω is data space of the mutual distribution for an atrial and ventricular combined statistical distribution signal.
8. A system according to claim 1 , wherein
said signal processor uses predetermined mapping information, associating ranges of said distribution data or values derived from said distribution data with corresponding medical conditions, and compares said distribution data or values derived from said distribution data, with said ranges and generates an alert message indicating a potential medical condition.
9. A system according to claim 8 , wherein
said predetermined mapping information associates ranges of said distribution data or values derived from said distribution data with particular patient demographic characteristics and with corresponding medical conditions and said signal processor uses patient demographic data including at least one of, age, weight, gender and height in comparing said distribution data or values derived from said distribution data with said ranges and generating the alert message indicating the potential medical condition.
10. A system according to claim 1 , wherein
said signal processor uses predetermined mapping information, associating a threshold value with said distribution data or values derived from said distribution data with corresponding medical conditions, and compares said distribution data or values derived from said distribution data, with said threshold value and generates an alert message indicating a potential medical condition.
11. A method for heart performance characterization and abnormality detection, comprising the steps of:
receiving,
first sampled data representing a first signal portion of a heart electrical activity related signal and
second sampled data representing a second signal portion of the heart electrical activity related signal; and
determining distribution data associated with degree of similarity between the first and second signal portions by determining a difference between
(a) values derived by applying a first function to mean adjusted sampled values of the first signal portion and
(b) values derived by applying a second function to mean adjusted sampled values of the second signal portion and
in response to the distribution data, initiating generation of a message associated with said degree of similarity between the first and second signal portions; and
deriving a regularity value by summing a plurality of values individually comprising a product of a determined distribution data value and a logarithm of said distribution data value.
12. A method according to claim 11 , wherein
said first function and said second function comprise probability density functions.
13. A method according to claim 11 , wherein
said mean adjusted sampled values of the first signal portion are derived by taking a difference between individual sampled values of said first signal portion and an average of said sampled values of said first signal portion and
said mean adjusted sampled values of the second signal portion are derived by taking a difference between individual sampled values of said second signal portion and an average of said sampled values of said second signal portion.
14. A method according to claim 11 , wherein
said first function and said second function comprise Gaussian functions.
15. A method according to claim 11 , wherein
said first function and said second function comprise a same function.
16. A system according to claim 1 , wherein
said first function and said second function comprise a same function.
17. A system according to claim 1 , wherein
said first signal portion and said second signal portion are in a single heart cycle.
18. A method according to claim 11 , wherein
said first signal portion and said second signal portion are associated with atrial and ventricular repolarization procedures, respectively.
19. A system according to claim 1 , wherein said heart electrical activity related signal comprises at least one of an electro-cardiogram (ECG) signal and an intra-cardiac electrogram (ICEG) signal.