System for cardiac arrhythmia detection
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 multiple heart beat cycles and for receiving a pace signal indicating occurrence of a heart pace pulse applied to the heart. A signal processor uses the received sampled data and pace signal in calculating, a first signal characteristic value comprising a time interval between occurrence of the pace pulse and a cardiac cycle characteristic and a second signal characteristic comprising an average of the time intervals determined over a multiple heart cycles. A comparator compares at least one of the first and second characteristic values with a threshold value to provide a comparison indicator. A patient monitor generates an alert message associated with the threshold in response to the comparison indicator indicating a calculated signal characteristic value exceeds the threshold value.
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 a plurality of heart beat cycles and for receiving a pace signal indicating occurrence of a heart pace pulse applied to the heart;
a signal processor for using the received sampled data and pace signal in,
determining a plurality of first signal characteristic values over a plurality of heart cycles, an individual first signal characteristic value comprising a time interval between occurrence of said pace pulse and a cardiac cycle characteristic and
calculating a second signal characteristic comprising an average of said plurality of first signal characteristic values, said signal processor identifying a number of successful heart beats over a time period;
a comparator configured to compare at least one of the first and second characteristic values with a threshold value to provide a comparison indicator and to compare said number of successful heart beats with a corresponding number of pacing pulses provided in the time period to derive a heart performance indicator; and
a patient monitor for in response to said comparison indicator indicating a 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 time interval occurs within a single heart cycle.
3. A system according to claim 1 , wherein
said comparator determines a comparison indicator indicating whether said at least one of the first and second characteristic values lies in a predetermined value range and
said patient monitor, in response to said comparison indicator indicating a calculated signal characteristic value lies in a predetermined value range, generates an alert message associated with the value range.
4. A system according to claim 1 , wherein
said cardiac cycle characteristic comprises at least one of, (a) a Q wave point, (a) an R wave point, (c) an S wave point and (d) a T wave point.
5. A system according to claim 1 , wherein
said threshold value is derived from recorded electrical signal data for said patient.
6. A system according to claim 1 , wherein
said threshold value is derived from recorded electrical signal data for a population of patients.
7. A system according to claim 6 , 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.
8. A system according to claim 1 , wherein
said signal processor dynamically adjusts said threshold value in response to a determined sensitivity of arrhythmia detection.
9. A system according to claim 1 , wherein
said signal processor calculates said average of said first signal characteristic values determined over a plurality of heart cycles as,
1
N
∑
i
∈
N
Pace_X
(
i
)
where, Pace_X is the time interval between pacing spike and occurrence of said cardiac cycle characteristic and N is a calculation window size as there are N heart beats in a calculation window.
10. A system according to claim 1 , wherein
said signal processor calculates a standard deviation of said first signal characteristic values determined over a plurality of heart cycles and
said patient monitor, in response to a comparison indicator indicating a calculated standard deviation value exceeds a predetermined threshold value, generates an alert message.
11. A system according to claim 10 , wherein
said signal processor calculates a standard deviation of said first signal characteristic values determined over a plurality of heart cycles as,
1
N
-
1
∑
i
∈
N
-
1
(
Pace_X
(
i
)
-
μ
(
Pace_X
)
)
where, Pace_X is the time interval between pacing spike and occurrence of said cardiac cycle characteristic and N is a calculation window size as there are N heart beats in a calculation window and μ(Pace_X) is the calculated average of said first signal characteristic values.
12. A system according to claim 1 , wherein
said signal processor calculates a signal variability of said first signal characteristic values determined over a plurality of heart cycles and
said patient monitor, in response to a comparison indicator indicating a calculated signal variability value exceeds a predetermined threshold value, generates an alert message.
13. A system according to claim 12 , wherein
said signal processor calculates a signal variability of said first signal characteristic values determined over a plurality of heart cycles as,
μ
(
Pace_X
)
ϕ
(
Pace_X
)
or
its
reciprocal
,
where, Pace_X is the time interval between pacing spike and occurrence of said cardiac cycle characteristic and N is a calculation window size as there are N heart beats in a calculation window and μ(Pace_X) is the calculated average of said first signal characteristic values and φ(Pace_X) is the standard deviation of said first signal characteristic values determined over a plurality of heart cycles.
14. A system according to claim 1 , wherein
said signal processor calculates a signal variation of said first signal characteristic values determined over a plurality of heart cycles and
said patient monitor, in response to a comparison indicator indicating a calculated signal variation value exceeds a predetermined threshold value, generates an alert message.
15. A system according to claim 14 , wherein
said signal processor calculates a signal variation of said first signal characteristic values determined over a plurality of heart cycles as,
max
(
Pace_X
-
μ
(
Pace_X
)
)
μ
(
Pace_X
)
or
its
reciprocal
,
where, Pace_X is the time interval between pacing spike and occurrence of said cardiac cycle characteristic and N is a calculation window size as there are N heart beats in a calculation window and μ(Pace_X) is the calculated average of said first signal characteristic values.
16. A system according to claim 1 , wherein
said threshold value is derived from recorded electrical signal data for a population of patients and said signal processor dynamically adjusts said threshold value in response to a determined sensitivity of arrhythmia detection.
17. A system according to claim 1 , including
a repository of predetermined mapping information, associating ranges of the first or second characteristic values with corresponding medical conditions and
said comparator compares the first or second characteristic values with said ranges to provide a comparison indicator identifying a medical condition and
said patient monitor generates an alert message identifying said medical condition.
18. A system according to claim 17 , wherein
said predetermined mapping information associates ranges of the first or second characteristic values 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.
19. 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 a plurality of heart beat cycles and for receiving a pace signal indicating occurrence of a heart pace pulse applied to the heart;
a signal processor for using the received sampled data and pace signal in,
determining a plurality of first signal characteristic values over a plurality of heart cycles, an individual first signal characteristic value comprising a time interval between occurrence of said pace pulse and a cardiac cycle characteristic and
calculating a second signal characteristic comprising an average of said plurality of first signal characteristic values, said signal processor identifying a number of successful heart beats over a time period;
a repository of mapping information, associating ranges of the first or second characteristic values with corresponding medical conditions;
a comparator configured to compare at least one of the first and second characteristic values with a threshold value to provide a comparison indicator and to compare the first or second characteristic values with said ranges to provide a comparison indicator identifying a medical condition and to compare said number of successful heart beats with a corresponding number of pacing pulses provided in the time period to derive a heart performance indicator; and
a patient monitor for in response to said comparison indicator indicating a calculated signal characteristic value exceeds the threshold value, generating a message associated with the threshold and generating a message identifying said medical condition.
20. 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 a plurality of heart beat cycles;
receiving a pace signal indicating occurrence of a heart pace pulse applied to the heart;
using the received sampled data and pace signal in,
determining a plurality of first signal characteristic values over a plurality of heart cycles, an individual first signal characteristic value comprising a time interval between occurrence of said pace pulse and a cardiac cycle characteristic,
calculating a second signal characteristic comprising an average of said plurality of first signal characteristic values and
identifying a number of successful heart beats over a time period and
comparing said number of successful heart beats with a corresponding number of pacing pulses provided in the time period to derive a heart performance indicator;
comparing at least one of the first and second characteristic values with a threshold value to provide a comparison indicator; and
in response to said comparison indicator indicating a calculated signal characteristic value exceeds the threshold value, generating an alert message associated with the threshold.