Patent ID: 12207918

DESCRIPTION OF EXEMPLIFYING AND NON-LIMITING EMBODIMENTS

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.

FIG.1shows a schematic illustration of an apparatus100according 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 interface101for receiving a signal indicative of cardiac motion and a processing system102coupled to the signal interface101. The processing system102is 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, andset 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.

The above-mentioned signal is produced with a sensor system103that is responsive to cardiac motion. In the exemplifying situation shown inFIG.1, the sensor system103is placed on the chest of an individual107. The sensor system103may comprise for example a gyroscope, an accelerometer, and/or an inertial measurement unit “IMU” comprising both an accelerometer and a gyroscope. The sensor system103can 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-interface104. 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.

In the exemplifying case illustrated inFIG.1, the sensor system103is connected to the signal interface101via 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 system103to the signal interface101may take place either directly or via a data transfer network105such as e.g. a telecommunications network. In the exemplifying case illustrated inFIG.1, the sensor system103is connected to a radio transmitter. It is also possible that the apparatus comprising the processing device102is 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.

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 memory106for recording the signal and/or the apparatus may comprise a data port for connecting to an external memory.

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 system102is configured to compute the indicator quantity according to the formula:
Σi=1N(xi2+yi2+z12),  (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, xiis an ithsample of cardiac rotation with respect to the x-direction of a cartesian coordinate system199, yiis an ithsample of cardiac rotation with respect to the y-direction of the cartesian coordinate system199, and ziis an ithsample of cardiac rotation with respect to the z-direction of the cartesian coordinate system199. In an exemplifying case where the signal is measured with a three-axis accelerometer, xiis an ithsample of acceleration in the x-direction of the cartesian coordinate system199, yiis an ithsample of acceleration in the y-direction of the cartesian coordinate system199, and ziis an ithsample of acceleration in the z-direction of the cartesian coordinate system199. It is also possible that the sensor system comprises both a gyroscope and an accelerometer. In this exemplifying case, the processing system102can 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.

In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system102is 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.

In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system102is 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 system102is 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.

In an apparatus according to an exemplifying and non-limiting embodiment of the invention, the processing system102is 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.

The processing system102can 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 memory106can be implemented for example with one or more memory circuits, each of which can be e.g. a random-access memory “RAM” device.

FIG.2aillustrates 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 ((xi2)}+yi2+zi2),  (2)
where i is an index increasing with time, xiis an ithsample of the cardiac rotation with respect to the x-direction of the cartesian coordinate system199shown inFIG.1, yiis an ithsample of the cardiac rotation with respect to the y-direction of the cartesian coordinate system199, and ziis an ithsample of the cardiac rotation with respect to the z-direction of the cartesian coordinate system199.

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

FIG.3aillustrates 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.3billustrates 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 byFIGS.2a,2b,3a, and3b, the energy related to diastolic phases of heart-beat periods is greater in the cases of the HFpEF shown inFIGS.3aand3bthan in the normal cases shown inFIGS.2aand2b.

FIG.4aillustrates 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 system199shown inFIG.1.FIG.4billustrates 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 byFIGS.4aand4b, the energy related to diastolic phases of heart-beat periods is greater in the case of the HFpEF than in the normal case.

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: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, andset an output signal to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

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).

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.

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.

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.

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.

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.

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.