APPARATUS FOR PRODUCING INFORMATION INDICATIVE OF CARDIAC ABNORMALITY

Abstract

An apparatus for producing information indicative of cardiac abnormality, for example Heart failure with preserved ejection fraction “HFpEF”, includes a signal interface for receiving a signal indicative of cardiac motion and a processing system coupled to the signal interface. The processing system is configured to extract, from the signal, temporal portions which belong to diastolic phases of a heart. The processing system is configured to set an output signal of the apparatus to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

Claims

1. An apparatus comprising: a signal interface for receiving a signal indicative of cardiac motion, and a processing system coupled to the signal interface, wherein the processing system is configured to: extract, from the signal, temporal portions which belong to diastolic phases of a heart, form an indicator quantity indicative of energy of the temporal portions belonging to the diastolic phases, and set an output signal of the apparatus to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

2. The apparatus according to claim 1, wherein the apparatus comprises a sensor system for producing the signal indicative of the cardiac motion.

3. The apparatus according to claim 2, wherein the sensor system comprises a gyroscope for measuring cardiac angular rotations.

4. The apparatus according to claim 2, wherein the sensor system comprises an accelerometer for measuring cardiac accelerations.

5. The apparatus according to claim 1, wherein the processing system is configured to compute the indicator quantity according to the formula: $\underset{i=1}{\overset{N}{.Math.}}\left(x_i^2+y_i^2+z_i^2\right),$ where i is an index increasing with time, N is a number of samples of the temporal portions belonging to the diastolic phases, x.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, an x-direction of a cartesian coordinate system (199), y.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a y-direction of the cartesian coordinate system, and z.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a z-direction of the cartesian coordinate system.

6. The apparatus according to claim 1, wherein the processing system is configured to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

7. The apparatus according to claim 1, wherein the processing system is configured to set the output signal to express presence of a heart failure with preserved ejection fraction “HFpEF” in response to a situation in which the indicator quantity exceeds the threshold value.

8. A non-transitory computer readable medium on which is stored a computer program for controlling a programmable processing system to process a signal indicative of cardiac motion, the computer program comprising computer executable instructions that, when executed by the programmable processing system, causes the programmable processing system to: extract, from the signal, temporal portions which belong to diastolic phases of a heart, form an indicator quantity indicative of energy of the temporal portions belonging to the diastolic phases, and set an output signal to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

9. The non-transitory computer readable medium of claim 8, wherein the computer program comprises computer executable instructions for controlling the programmable processing system to compute the indicator quantity according to the formula: $\underset{i=1}{\overset{N}{.Math.}}\left(x_i^2+y_i^2+z_i^2\right),$ where i is an index increasing with time, N is a number of samples of the temporal portions belonging to the diastolic phases, x.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, an x-direction of a cartesian coordinate system (199), y.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a y-direction of the cartesian coordinate system, and z.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a z-direction of the cartesian coordinate system.

10. The non-transitory computer readable medium of claim 8, wherein the computer program comprises computer executable instructions for controlling the programmable processing system to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

11. The non-transitory computer readable medium of claim 8, wherein the computer program comprises computer executable instructions for controlling the programmable processing system to set the output signal to express presence of a heart failure with preserved ejection fraction “HFpEF” in response to a situation in which the indicator quantity exceeds the threshold value.

12. (canceled)

13. The apparatus according to claim 3, wherein the sensor system comprises an accelerometer for measuring cardiac accelerations.

14. The non-transitory computer readable medium of claim 9, wherein the computer program comprises computer executable instructions for controlling the programmable processing system to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

15. The apparatus according to claim 2, wherein the processing system is configured to compute the indicator quantity according to the formula: $\underset{i=1}{\overset{N}{.Math.}}\left(x_i^2+y_i^2+z_i^2\right),$ where i is an index increasing with time, N is a number of samples of the temporal portions belonging to the diastolic phases, x.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, an x-direction of a cartesian coordinate system (199), y.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a y-direction of the cartesian coordinate system, and z.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a z-direction of the cartesian coordinate system.

16. The apparatus according to claim 3, wherein the processing system is configured to compute the indicator quantity according to the formula: $\underset{i=1}{\overset{N}{.Math.}}\left(x_i^2+y_i^2+z_i^2\right),$ where i is an index increasing with time, N is a number of samples of the temporal portions belonging to the diastolic phases, x.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, an x-direction of a cartesian coordinate system (199), y.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a y-direction of the cartesian coordinate system, and z.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a z-direction of the cartesian coordinate system.

17. The apparatus according to claim 4, wherein the processing system is configured to compute the indicator quantity according to the formula: $\underset{i=1}{\overset{N}{.Math.}}\left(x_i^2+y_i^2+z_i^2\right),$ where i is an index increasing with time, N is a number of samples of the temporal portions belonging to the diastolic phases, x.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, an x-direction of a cartesian coordinate system (199), y.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a y-direction of the cartesian coordinate system, and z.sub.i is an i.sup.th sample of cardiac rotation with respect to, or acceleration in, a z-direction of the cartesian coordinate system.

18. The apparatus according to claim 2, wherein the processing system is configured to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

19. The apparatus according to claim 3, wherein the processing system is configured to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

20. The apparatus according to claim 4, wherein the processing system is configured to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

21. The apparatus according to claim 5, wherein the processing system is configured to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most 50% of the corresponding diastolic phase.

Description

BRIEF DESCRIPTION OF FIGURES

[0020] Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below with reference to the accompanying drawings, in which:

[0021] FIG. 1 shows a schematic illustration of an apparatus according to an exemplifying and non-limiting embodiment of the invention for producing information indicative of cardiac abnormality,

[0022] FIG. 2a illustrates a waveform of an exemplifying signal indicative of cardiac rotation in a normal case when an individual under consideration is at rest, and FIG. 2b illustrates a waveform of another exemplifying signal indicative of cardiac rotation measured from the same individual after adenosine triphosphate “ATP” infusion for widening coronary arteries,

[0023] FIG. 3a illustrates a waveform of an exemplifying signal indicative of cardiac rotation in a case of a heart failure with preserved ejection fraction “HFpEF” when an individual under consideration is at rest, and FIG. 3b illustrates a waveform of another exemplifying signal indicative of cardiac rotation measured from the same individual after adenosine triphosphate “ATP” infusion for widening coronary arteries, and

[0024] FIG. 4a illustrates a waveform of an exemplifying signal indicative of acceleration in the “through chest”-direction in a normal case when an individual under consideration is at rest, and FIG. 4b illustrates a waveform of another exemplifying signal indicative of acceleration in the “through chest”-direction in a case of a heart failure with preserved ejection fraction “HFpEF” when an individual under consideration is at rest.

DESCRIPTION OF EXEMPLIFYING AND NON-LIMITING EMBODIMENTS

[0025] The specific examples provided in the description below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.

[0026] FIG. 1 shows a schematic illustration of an apparatus 100 according to an exemplifying and non-limiting embodiment of the invention for producing information indicative of cardiac abnormality such as e.g. a heart failure with preserved ejection fraction “HFpEF”. The apparatus comprises a signal interface 101 for receiving a signal indicative of cardiac motion and a processing system 102 coupled to the signal interface 101. The processing system 102 is configured to: [0027] extract, from the signal, temporal portions which belong to diastolic phases of a heart, [0028] form an indicator quantity indicative of energy of the temporal portions belonging to the diastolic phases, and [0029] set an output signal of the apparatus to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

[0030] The above-mentioned signal is produced with a sensor system 103 that is responsive to cardiac motion. In the exemplifying situation shown in FIG. 1, the sensor system 103 is placed on the chest of an individual 107. The sensor system 103 may comprise for example a gyroscope, an accelerometer, and/or an inertial measurement unit “IMU” comprising both an accelerometer and a gyroscope. The sensor system 103 can be for example a microelectromechanical system “MEMS”. The temporal duration of the signal measured with the sensor system can be, for example but not necessarily, from tens of seconds to hours. The output signal of the apparatus can be for example a message shown on a display screen of a user-interface 104. The temporal portions which belong to the diastolic phases can be recognized and extracted from the signal with suitable known methods that can be based on e.g. known waveform complexes which are related to the systolic phase and to the diastolic phase, respectively.

[0031] In the exemplifying case illustrated in FIG. 1, the sensor system 103 is connected to the signal interface 101 via one or more data transfer links each of which can be for example a radio link or a corded link. The data transfer from the sensor system 103 to the signal interface 101 may take place either directly or via a data transfer network 105 such as e.g. a telecommunications network. In the exemplifying case illustrated in FIG. 1, the sensor system 103 is connected to a radio transmitter. It is also possible that the apparatus comprising the processing device 102 is integrated with the sensor system. In this exemplifying case, the signal interface is actually a simple wiring from the sensor system to the processing device. An apparatus comprising an integrated sensor system can be for example a smartphone or another hand-held device which can be placed on the chest of an individual during a measurement phase.

[0032] An apparatus according to an exemplifying and non-limiting embodiment of the invention is configured to record the signal indicative of cardiac motion. The recorded signal can be measured within a time window having a fixed temporal start-point and a fixed temporal end-point or within a sliding time window having a fixed temporal length and moving along with elapsing time. The apparatus may comprise an internal memory 106 for recording the signal and/or the apparatus may comprise a data port for connecting to an external memory.

[0033] There are numerous ways to form the indicator quantity indicative of the energy related to the diastolic phases of heart-beat periods. In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system 102 is configured to compute the indicator quantity according to the formula:

Σ.sub.i=1.sup.N(x.sub.i.sup.2+y.sub.i.sup.2+z.sub.1.sup.2),  (1)

where i is an index increasing with time, and N is the number of samples taken from the signal during the diastolic phases of heart-beat periods. In an exemplifying case where the signal is measured with a three-axis gyroscope, x.sub.i is an i.sup.th sample of cardiac rotation with respect to the x-direction of a cartesian coordinate system 199, y.sub.i is an i.sup.th sample of cardiac rotation with respect to the y-direction of the cartesian coordinate system 199, and z.sub.i is an i.sup.th sample of cardiac rotation with respect to the z-direction of the cartesian coordinate system 199. In an exemplifying case where the signal is measured with a three-axis accelerometer, x.sub.i is an i.sup.th sample of acceleration in the x-direction of the cartesian coordinate system 199, y.sub.i is an i.sup.th sample of acceleration in the y-direction of the cartesian coordinate system 199, and z.sub.i is an i.sup.th sample of acceleration in the z-direction of the cartesian coordinate system 199. It is also possible that the sensor system comprises both a gyroscope and an accelerometer. In this exemplifying case, the processing system 102 can be configured apply the above-presented formula (1) for both the x-, y-, and z-components of the cardiac rotation and the x-, y-, and z-components of the acceleration. The final indicator quantity can be e.g. a weighted sum of the results computed for the cardiac rotation and for the acceleration.

[0034] In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system 102 is configured to set the output signal of the apparatus to express presence of a heart failure with preserved ejection fraction “HFpEF” in response to a situation in which the indicator quantity exceeds the threshold value.

[0035] In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system 102 is configured to maintain a series of threshold values where each threshold value represents a specific probability of cardiac abnormality e.g. the HFpEF. The processing system 102 is configured to set the output signal of the apparatus to express the probability of cardiac abnormality based on results of comparisons between the indicator quantity and the threshold values.

[0036] In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system 102 is configured to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases. Each end-part may cover at most e.g. 50% or 30% of the corresponding diastolic phase. According to empirical data, the energy of temporal portions of a signal measured with an accelerometer and representing the end-parts of diastolic periods can be used as an indicator of the HFpEF.

[0037] The processing system 102 can be implemented for example with one or more processor circuits, each of which can be a programmable processor circuit provided with appropriate software, a dedicated hardware processor such as, for example, an application specific integrated circuit “ASIC”, or a configurable hardware processor such as, for example, a field programmable gate array “FPGA”. The memory 106 can be implemented for example with one or more memory circuits, each of which can be e.g. a random-access memory “RAM” device.

[0038] FIG. 2a illustrates the waveform of an exemplifying signal indicative of cardiac rotation in a normal case when an individual under consideration is at rest. In an exemplifying case where the signal is measured with a three-axis gyroscope, the cardiac rotation can be defined as:

√{square root over ((x.sub.i.sup.2)}+y.sub.i.sup.2+z.sub.i.sup.2),  (2)

where i is an index increasing with time, x.sub.i is an i.sup.th sample of the cardiac rotation with respect to the x-direction of the cartesian coordinate system 199 shown in FIG. 1, y.sub.i is an i.sup.th sample of the cardiac rotation with respect to the y-direction of the cartesian coordinate system 199, and z.sub.i is an i.sup.th sample of the cardiac rotation with respect to the z-direction of the cartesian coordinate system 199.

[0039] FIG. 2b illustrates the waveform of an exemplifying signal indicative of cardiac rotation measured from the same individual after adenosine triphosphate “ATP” infusion for widening coronary arteries.

[0040] FIG. 3a illustrates the waveform of an exemplifying signal indicative of cardiac rotation in a case of a heart failure with preserved ejection fraction “HFpEF” when an individual under consideration is at rest. FIG. 3b illustrates the waveform of an exemplifying signal indicative of cardiac rotation measured from the same individual after adenosine triphosphate “ATP” infusion for widening coronary arteries. As shown by FIGS. 2a, 2b, 3a, and 3b, the energy related to diastolic phases of heart-beat periods is greater in the cases of the HFpEF shown in FIGS. 3a and 3b than in the normal cases shown in FIGS. 2a and 2b.

[0041] FIG. 4a illustrates a waveform of an exemplifying signal indicative of acceleration in the “through chest”-direction in a normal case when an individual under consideration is at rest. The through chest”-direction is the z-direction of the cartesian coordinate system 199 shown in FIG. 1. FIG. 4b illustrates a waveform of an exemplifying signal indicative of acceleration in the “through chest”-direction in a case of a heart failure with preserved ejection fraction “HFpEF” when an individual under consideration is at rest. As shown by FIGS. 4a and 4b, the energy related to diastolic phases of heart-beat periods is greater in the case of the HFpEF than in the normal case.

[0042] A computer program according to an exemplifying and non-limiting embodiment of the invention comprises software modules for producing information indicative of cardiac abnormality, e.g. HFpEF, on the basis of a signal indicative of cardiac motion. The software modules comprise computer executable instructions for controlling a programmable processing system to: [0043] extract, from the signal, temporal portions which belong to diastolic phases of a heart, [0044] form an indicator quantity indicative of energy of the temporal portions belonging to the diastolic phases, and [0045] set an output signal to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

[0046] In a computer program according to an exemplifying and non-limiting embodiment of the invention, the software modules comprise computer executable instructions for controlling the programmable processing system to compute the indicator quantity according to the above-presented formula (1).

[0047] In a computer program according to an exemplifying and non-limiting embodiment of the invention, the software modules comprise computer executable instructions for controlling the programmable processing system to extract, from the signal, the temporal portions so that the extracted temporal portions represent end-parts of the diastolic phases, each end-part covering at most e.g. 50% or 30% of the corresponding diastolic phase.

[0048] In a computer program according to an exemplifying and non-limiting embodiment of the invention, the software modules comprise computer executable instructions for controlling the programmable processing system to set the output signal to express presence of the HFpEF in response to a situation in which the indicator quantity exceeds the threshold value.

[0049] The software modules can be e.g. subroutines or functions implemented with a suitable programming language and with a compiler suitable for the programming language and for the programmable processing system under consideration. It is worth noting that also a source code corresponding to a suitable programming language represents the computer executable software modules because the source code contains the information needed for controlling the programmable processing system to carry out the above-presented actions and compiling changes only the format of the information. Furthermore, it is also possible that the programmable processing system is provided with an interpreter so that a source code implemented with a suitable programming language does not need to be compiled prior to running.

[0050] A computer program product according to an exemplifying and non-limiting embodiment of the invention comprises a computer readable medium, e.g. a compact disc (“CD”), encoded with a computer program according to an embodiment of invention.

[0051] A signal according to an exemplifying and non-limiting embodiment of the invention is encoded to carry information defining a computer program according to an embodiment of invention.

[0052] The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.