System for cardiac pathology detection and characterization
A system for heart performance characterization and abnormality detection includes an interface for receiving digitized electrical signals representing blood pressure waveforms over one or more heart beat cycles. The digitized electrical signals comprise, a first digital data sequence representing normal blood pressure of a patient, a second digital data sequence representing random blood pressure of a normal patient and a third digital data sequence representing a potentially abnormal blood pressure of a patient. A complexity processor calculates first, second and third complexity indices for the corresponding first, second and third digital data sequences respectively. A correlation processor uses the calculated first, second and third complexity indices to calculate one or more measures indicating deviation of the potentially abnormal blood pressure of the patient from a normal value.
1. A system for heart performance characterization and abnormality detection included in a medical device, the system comprising:
an interface configured to receive, from a blood pressure sensor coupled to the interface, digitized electrical signals representing blood pressure waveforms over one or more heartbeat cycles comprising,
a first digital data sequence representing a baseline blood pressure waveform of at least one of a first patient and a second patient having common characteristics as the first patient including at least one of age, weight, gender, height, and medical conditions,
a second digital data sequence representing a random blood pressure waveform that is derived by a computer and
a third digital data sequence representing an ongoing blood pressure waveform of the first patient;
a complexity processor configured to calculate first, second and third complexity values for the corresponding first, second and third digital data sequences respectively;
a correlation processor configured to determine one or more measures based on nonlinear changes of the ongoing blood pressure waveform with respect to the baseline blood pressure waveform and based on the first, second and third complexity values;
a data processor configured to determine a first anatomical location of the first patient and a type of cardiac pathology and/or associated disease based on the one or more determined measures and a second anatomical location of the first patient at which the ongoing blood pressure waveform is acquired; and
a transmitter configured to transmit a message to a user indicating the determined type of cardiac pathology and/or associated disease of the first patient.
2. The system according to claim 1 , wherein
said interface substantially synchronizes the first, second and third digital data sequences.
3. The system according to claim 2 , wherein
said interface substantially synchronizes the first, second and third digital data sequences in response to a peak or minimum value in the corresponding blood pressure waveforms.
4. The system according to claim 1 , wherein the data processor is further configured to monitor said first, second and third complexity values and in response to a variation in the values exceeding a predetermined threshold, generate an alert message.
5. The system according to claim 4 , wherein
said data processor substantially continuously performs the monitoring for at least a 24 hour period.
6. The system according to claim 4 , wherein
said data processor uses predetermined mapping information, associating ranges of said values with corresponding medical conditions, in comparing said values with said ranges and generates an alert message indicating a potential medical condition.
7. The system according to claim 6 , wherein
said predetermined mapping information associates ranges of said values with particular demographic characteristics for a population of patients and with corresponding medical conditions and said data processor uses patient demographic data for the population of patients including at least one of age, weight, gender and height in comparing said values with said ranges and generating the alert message indicating a potential medical condition.
8. The system according to claim 6 , wherein
said first digital data sequence representing said baseline blood pressure waveform is provided from stored blood pressure data of at least one of (a) said first patient and (b) said second patient having common demographic characteristics as said first patient including the at least one of age, weight, gender, height, and medical conditions as said first patient.
9. A method for heart performance characterization and abnormality detection performed by a medical device, the method performed using a computer system of the medical device including a processor and comprising the activities of:
receiving, by the processor from a blood pressure sensor, digitized electrical signals representing blood pressure waveforms over one or more heartbeat cycles comprising,
a first digital data sequence representing a baseline heart blood pressure waveform of at least one of a first patient and a second patient having common characteristics as the first patient including at least one of age, weight, gender, height, and medical conditions,
a second digital data sequence representing a random blood pressure waveform derived by a computer and
a third digital data sequence representing an ongoing heart blood pressure waveform of the second patient;
calculating, by the processor, first, second and third complexity values for the corresponding first, second and third digital data sequences respectively;
determining, by the processor, one or more measures based on nonlinear changes of the ongoing heart blood pressure waveform with respect to the baseline heart blood pressure waveform and based on the first, second and third complexity values,
determining, by the processor, a first anatomical location and a type of cardiac pathology and/or associated disease based on the one or more determined measures and a second anatomical location of the second patient at which the ongoing blood pressure waveform is acquired; and
transmitting a message to a user indicating the determined type of cardiac pathology and/or associated disease of the second patient.
10. A system for heart performance characterization and abnormality detection included in a medical device, the system comprising:
an interface configured to receive, from a blood pressure sensor coupled to the interface, a digitized electrical signal representing a blood pressure waveform over one or more heartbeat cycles;
a data processor configured to perform a Fourier transform on said digitized electrical signal to derive data representing individual frequency components of said digitized electrical signal;
a calculation processor configured to determine measures comprising,
(a) a first value representing a summation of the square of individual Fourier transform values of corresponding individual components of said individual frequency components and
(b) a second value representing a square of the summation of individual Fourier transform values of corresponding individual components of said individual frequency components; and
a correlation processor configured to use the calculated first and second values to calculate one or more measures based on nonlinear changes of a blood pressure of a patient from a baseline blood pressure value;
a processor configured to determine a first anatomical location and a type of cardiac pathology and/or associated disease based on the one or more calculated measures and a second anatomical location of the patient at which the blood pressure waveform is acquired; and
a transmitter configured to transmit a message to a user indicating the determined location and the determined type of cardiac pathology and/or associated disease of the patient, wherein
said correlation processor is further configured to calculate a ratio employing said first and second values using the following equation,
γ
xx
(
f
)
=
1
N
∑
n
=
1
N
X
n
(
f
)
2
1
N
∑
n
=
1
N
X
n
(
f
)
2
,
where γ xx is a coherence function ration, X n (f) is a Fourier transform of data points x 1 , . . . x N , N is a number of the data points and f is a frequency.
11. The system according to claim 10 , wherein
said interface synchronizes said digitized electrical signal.
12. The system according to claim 11 , wherein
said interface substantially synchronizes said digitized electrical signal in response to a peak or minimum value in the corresponding blood pressure waveforms.
13. The system according to claim 10 , wherein
said correlation processor calculates a ratio employing said first and second values comprising,
spectrum_coherence
=
γ
_
γ
_
+
∑
Ω
Θ
(
γ
^
(
e
jw
)
-
y
_
)
with
Θ
(
x
)
=
{
0.0
,
if
x
<
Θ
γ
_
x
,
if
x
≥
Θ
γ
_
}
where, x is a data point value, γ is a mean coherence function ratio, {circumflex over (γ)} is a current calculated coherence function ratio, ω is a phase, j is an imaginary unit, Ω is a frequency spectrum and Θ is a fixed threshold value, 0<Θ<1 and the Spectrum coherence index is near 1 when the ongoing blood pressure waveform signal is healthy and spectrum coherence index of the blood pressure waveform decreases towards zero due to abnormality in a blood pressure waveform.