System for heart monitoring, characterization and abnormality detection
A system analyzes and characterizes cardiac electrophysiological signals by determining instantaneous signal entropy for identifying and characterizing cardiac disorders, differentiating cardiac arrhythmias, determining pathological severity and predicting life-threatening events. A system for heart monitoring, characterization and abnormality detection, includes an acquisition device for acquiring an electrophysiological signal representing a heart beat cycle of a patient heart. A signal processor derives an entropy representative value of the acquired electrophysiological signal within a time period comprising at least a portion of a heart beat cycle of the acquired electrophysiological signal and provides an entropy value as a function of the entropy representative value and the time period. A comparator generates data representing a message for communication to a destination device in response to the entropy value exceeding a predetermined threshold.
1. A system for heart monitoring, characterization and abnormality detection, comprising:
an acquisition device for acquiring an electrophysiological signal representing a heart beat cycle of a patient heart;
a signal processor for,
deriving an entropy representative value of the amplitude variation of the acquired electrophysiological signal within a time period comprising at least a portion of a heart beat cycle of the acquired electrophysiological signal and
using a predetermined function to process said entropy representative value and data representing said time period to provide an entropy value; and
a comparator for generating data representing a message for communication to a destination device in response to said entropy value exceeding a predetermined threshold.
2. A system according to claim 1 , wherein
said signal processor divides said entropy value by the time period duration value in response to said predetermined function.
3. A system according to claim 1 , wherein
said time period comprises a window within said heart beat cycle and including
a user interface enabling a user to adaptively select the window within said heart beat cycle and focus signal analysis on a particular portion of said heart beat cycle.
4. A system according to claim 1 , wherein
said comparator compares said entropy value with a plurality of predetermined thresholds indicating a plurality of predetermined signal value ranges, to identify a type of cardiac event.
5. A system according to claim 1 , wherein
said comparator compares said entropy value with a plurality of predetermined thresholds indicating a plurality of predetermined signal value ranges, to characterize cardiac signal quality.
6. A system according to claim 4 , wherein
said comparator adaptively selects said plurality of predetermined thresholds in response to patient demographic information including at least one of, (a) patient height, (b) patient weight, (c) patient gender, (d) patient age and (e) patient pregnancy status.
7. A system according to claim 1 , wherein
said signal processor processes the acquired electrophysiological signal and provides said entropy value for a plurality of successive heart beat cycles in a continuous patient monitoring mode.
8. A system according to claim 1 , wherein
said signal processor processes the acquired electrophysiological signal to derive an entropy representative value using a Shannon entropy function of form,
H
(
X
)
=
-
∑
i
=
1
n
p
(
x
i
)
·
log
b
(
p
(
x
i
)
)
Where, for a random variable X with n outcomes {x i :i=1, . . . , n}, the Shannon entropy is denoted by H(X), and p(x i ) is the probability mass function of outcome x i . n is the number of the X data sample size and log b (●) is a logarithm calculation (b=2 or 10 or another number).
9. A system according to claim 1 , wherein
said signal processor processes the acquired electrophysiological signal to derive an entropy representative value using an instantaneous Shannon entropy (ISE) function of the form,
ISE
=
H
(
P
)
t
1
-
H
(
P
)
t
2
t
2
-
t
1
,
where windowed Entropy H(P) t1 and H(P) t2 overlap between time t 1 and t 2 .
10. A system according to claim 1 , wherein
said system comprises a patient monitoring device.
11. A system according to claim 1 , wherein
said message indicates severity of a cardiac condition.
12. A system according to claim 1 , wherein
said message provides advance warning of myocardial ischemia or acute myocardial infarction in cases including non-symptomatic cases.
13. A system according to claim 1 , wherein
said message initiates treatment by at least one of, (a) initiating drug delivery and (b) initiating electrical stimulus or pacing of a heart.
14. A system for heart monitoring, characterization and abnormality detection, comprising:
an acquisition device for acquiring an electrophysiological signal representing a heart beat cycle of a patient heart;
a signal processor for,
deriving an entropy representative value of the amplitude variation of the acquired electrophysiological signal within a time period comprising at least a portion of a heart beat cycle of the acquired electrophysiological signal and
using a predetermined function to process said entropy representative value and a time value representing the time period to provide an entropy value; and
a comparator for generating data representing a message for communication to a destination device in response to determining said entropy value exceeds a predetermined threshold.
15. A system according to claim 14 , wherein
said time period comprises a window within said heart beat cycle and including
a user interface enabling a user to adaptively select the window within said heart beat cycle and focus signal analysis on a particular portion of said heart beat cycle.
16. A method for heart monitoring, characterization and abnormality detection, comprising the activities of:
acquiring an electrophysiological signal representing a heart beat cycle of a patient heart;
deriving an entropy representative value of the amplitude variation and distortion of the acquired electrophysiological signal within a time period comprising at least a portion of a heart beat cycle of the acquired electrophysiological signal and
using a predetermined function to process said entropy representative value and data representing said time period to provide an entropy value;
generating data representing a message; and
communicating the generated message to a destination device in response to said entropy value exceeding a predetermined threshold.