An apparatus for producing information indicative of a heart failure with reduced ejection fraction

Abstract

An apparatus for generating information indicating heart failure with reduced ejection fraction (HFrEF) includes a signal interface (101) for receiving a signal indicating cardiac-related angle rotation, and a processing system (102) coupled to the signal interface. The processing system is configured to extract the diastolic time portion of the heart from the signal. The processing system is configured to set an output signal of the apparatus to indicate the presence of heart failure with reduced ejection fraction based on a comparison between the index quantity and a threshold value.

Description

[Technical Field]

[0001] This disclosure generally relates to information on generating heart failure with a reduced ejection fraction (HFrEF). More specifically, this disclosure relates to a device for generating information indicating HFrEF. Furthermore, this disclosure relates to a computer program for generating information indicating HFrEF. [Previous Technology]

[0002] Abnormalities in the cardiovascular system that are not diagnosed and properly treated and / or treated can gradually reduce the cardiovascular system's ability to maintain the blood flow required to meet an individual's physical needs, especially when the individual experiences physical stress. For example, coronary flow reserve (CFR) is reduced not only by ischemic heart disease but also by heart failure (HF), a growing global health challenge that imposes significant economic responsibility and healthcare burden due to high hospitalization rates, morbidity, and mortality. Although HF is defined as a syndrome characterized by symptoms and examination findings, it can be further differentiated based on left ventricular ejection fraction (LVEF), and is thus classified as HFrEF (also known as systolic heart failure) and HFpEF (with preserved ejection fraction). HFpEF and HFrEF present with similar clinical symptoms but have different mortality rates; HFpEF is lower than HFrEF. In one case of HFrEF, the heart muscle cannot contract sufficiently, thus pumping less oxygenated blood into the body.

[0003] Currently, methods such as electrocardiography based on the electromagnetic phenomenon of the associated heartbeat, cardiac ultrasound, and electrocardiography based on cardiac motion are used for the identification and assessment of various cardiac-related abnormalities. A well-known example of electrocardiography based on the electromagnetic phenomenon of the associated heartbeat is the electrocardiogram (ECG), and examples of electrocardiography based on cardiac motion are gyroscope electrocardiography (GCG) and scintigraphy (SCG). Cardiac ultrasound is typically ultrasound-based and provides images of cross-sections of the heart, offering comprehensive information about cardiac structure and function, but requires expensive equipment and skilled operators. The ECG provides a rapid electrical assessment of the heart, but offers limited information about cardiac structure. Scintigraphy is a non-invasive accelerometer-based method in which vibrations in the precordial region of the heart are measured, while gyroscope electrocardiography is a non-invasive gyroscope-based method in which angular rotation of the heart is measured. In this document, the term "gyroscope" encompasses various types of sensors used to measure angular rotation.

[0004] The aforementioned heart failure with reduced ejection fraction, "HFrEF", can be detected quite directly using ultrasound-based echocardiography. However, there is still a need for an HFrEF detection method that can be implemented using commonly used consumer products such as smartphones, so that users can conduct preliminary assessments of possible HFrEF at home and transmit the detection results to the healthcare system for investigation. [Summary of the Invention]

[0005] The following simplified summary is provided to offer a basic understanding of some features of various embodiments of the invention. This summary is not a broad overview of the invention. It is neither intended to identify key or essential elements of the invention nor to describe the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description illustrating embodiments of the invention.

[0006] According to the present invention, a novel device is provided for generating information indicating heart failure with reduced ejection fraction (HFrEF). The device according to the invention includes a signal interface for receiving a signal indicating cardiac-related angle rotation, and a processing system coupled to the signal interface. The processing system is configured to: - extract a time portion of the diastolic phase of the heart from the signal; - form an index indicating the energy of the time portion of the diastolic phase; and - set an output signal of the device to indicate the presence of heart failure with reduced ejection fraction (HFrEF) based on a comparison between the index and a threshold value.

[0007] Based on empirical data, the above-mentioned energy parameters related to diastole can be used as an indicator of heart failure with reduced ejection fraction, “HFrEF”.

[0008] The aforementioned threshold values ​​compared with the stated index can be determined based on empirical data collected from a group of patients and healthy individuals. The threshold values ​​are not necessarily fixed, but can vary depending on the individual considered, over time, and / or on certain other factors. It is also possible to construct a series of threshold values, where each threshold value represents a specific probability of HFrEF.

[0009] The device may include a sensing system for measuring the signal indicating cardiac-related angular rotation. The sensing system may include a gyroscope for measuring cardiac-related angular rotation. The sensing system may also include an accelerometer for measuring cardiac acceleration in different directions, and the device may include a processor for computationally estimating cardiac-related angular rotation based on the measured accelerations in different directions. Mathematics for orientation determination using a triaxial accelerometer is, for example, proposed by Pedley M.: Tilt Sensing Using a Triaxial Accelerometer, Freescale Semiconductor Application Note, Document No.: AN3461, Rev. 6, 03 / 2013.

[0010] One illustrative and non-limiting embodiment of the device may be, for example, a smartphone or other handheld device, which includes a gyroscope and / or accelerometer. The device may be placed on a person's chest to measure signals generated by the heartbeat.

[0011] It is also possible that the signal interface of a device according to an illustrative and non-limiting embodiment can receive the signal from an external device including a suitable sensing system. It should also be noted that the device does not necessarily include means for measuring the signal indicating the rotation of the heart-related angle.

[0012] According to the present invention, a novel computer program is also provided for generating information indicating cardiac-related abnormalities based on the aforementioned signal indicating cardiac-related angle rotation. The computer program includes computer-executable instructions for controlling a programmable processing system: - extracting a time portion of the heart's diastolic phase from the signal; - forming an index indicating the energy of the time portion of the diastolic phase; and - setting an output signal to indicate the presence of heart failure with reduced ejection fraction (HFrEF) based on a comparison between the index and a threshold value.

[0013] According to the present invention, a novel computer program product is also provided. The computer program product includes a non-volatile computer-readable medium, such as an optical disc "CD", which is encoded with a computer program according to the present invention.

[0014] Various illustrative and non-limiting embodiments are described in the appended claims.

[0015] The best understanding of the various illustrative and non-limiting embodiments of the structure and operation methods, as well as their additional objects and advantages, will be achieved by reading the following specific examples of embodiments in conjunction with the accompanying drawings.

[0016] The verbs “include” and “contain” are used in this document as open restrictions, neither excluding nor requiring the existence of unmentioned features.

[0017] Unless otherwise expressly stated, the features set forth in the appended sub-items are freely combinable.

[0018] Furthermore, it will be understood that the use of “one” or “one” (i.e., singular form) throughout this document does not preclude plural forms.

Implementation Method

[0020] The specific examples provided in the following description should not be construed as limiting the scope and / or availability of the attached request. Unless otherwise expressly stated, the list and groups of examples provided in the description are not exhaustive.

[0021] Figure 1 shows a schematic diagram of an apparatus 100 for generating information indicating heart failure with reduced ejection fraction (HFrEF) according to an illustrative and non-limiting embodiment. The apparatus includes a signal interface 101 for receiving a signal indicating cardiac-related angle rotation, and a processing system 102 coupled to the signal interface 101. The processing system 102 is configured to: - extract a time portion of the heart's diastolic phase from the signal; - form an index indicating the energy of the time portion of the diastolic phase; and - set an output signal of the apparatus to indicate the presence of HFrEF based on a comparison between the index and a threshold value.

[0022] The aforementioned signal is generated using a sensor system 103 that responds to rotation of the heart-related angle. In the illustrative case shown in Figure 1, the sensor system 103 is mounted on the chest of a person 107. The sensor system 103 may include, for example, a gyroscope and / or an inertial measurement unit (IMU), which includes an accelerometer and a gyroscope. The sensor system 103 may also be a microelectromechanical system (MEMS). The gyroscope may be, for example, a Coriolis gyroscope (CVG), which uses a vibrating structure to determine the rate of rotation. The duration of the signal measured by the sensor system may (but does not necessarily) range from tens of seconds to several hours. The output signal of the device may be, for example, a message displayed on a display screen of a user interface 104. The portion of the time belonging to the diastolic phase can be identified and extracted from the signal using appropriate known methods, which may be based on, for example, known composite waveforms that separately correlate the systolic and diastolic phases.

[0023] In the illustrative scenario depicted in FIG1, the sensor system 103 is connected to the signal interface 101 via one or more data transmission links, each of which may be, for example, a radio link or a wired link. Data transmission from the sensor system 103 to the signal interface 101 may occur directly or via a data transmission network 105, such as a telecommunications network. In the illustrative scenario depicted in FIG1, the sensor system 103 is connected to a radio transmitter. Integration of the device including the processing device 102 and the sensor system is also possible. In this illustrative scenario, the signal interface is a simple cabling from the sensor system to the processing device. A device including an integrated sensor system may be, for example, a smartphone or other handheld device that may be placed on a person's chest during a measurement phase.

[0024] An illustrative and non-limiting embodiment of the device is configured to record a signal indicating cardiac-related angle rotation. The recorded signal may be measured within a time window having a fixed start point and a fixed end point, or within a sliding time window having a fixed length and shifting over time. The device may include an internal memory 106 for recording the signal, and / or the device may include a data port for connection to an external memory.

[0025] There are many ways to form the index quantity indicating the energy relative to the diastolic phase during a heartbeat. In one device according to an illustrative and non-limiting embodiment, the processing system 102 is configured to calculate the index quantity according to the following formula: (1) where i is an index that increases over time, N is the number of samples taken from the signal during the diastolic phase of a heartbeat, xi is the i-th sample of the heart-related rotation in the x-direction of a Cartesian coordinate system 199, yi is the i-th sample of the heart-related rotation in the y-direction of the Cartesian coordinate system 199, and zi is the i-th sample of the heart-related rotation in the z-direction of the Cartesian coordinate system 199. In this illustrative case, the signal indicating the heart-related angular rotation can be received from a three-axis gyroscope, and the signal has components indicating the rotation in the x, y, and z directions of the Cartesian coordinate system 199.

[0026] In one illustrative and non-limiting embodiment of the device, the processing system 102 is configured to maintain a series of threshold values, each threshold value representing a specific probability of HFrEF. The processing system 102 is configured to set the output signal of the device to represent the probability of HFrEF based on a comparison between the index value and the threshold value.

[0027] Heart failure with a reduced ejection fraction "HFrEF" and a preserved ejection fraction "HFpEF" is associated with a third heart sound S3, which is an additional heart sound that occurs shortly after the two normal heart sounds S1 and S2, which relate to aortic opening and aortic closure. The third heart sound S3 occurs at the beginning of the middle third of diastole, approximately 0.12 to 0.18 seconds after S2. The third heart sound S3 can be conceived as being caused by the oscillation of blood flowing into the atria between the ventricular walls. The reason for the third heart sound S3 occurring only in the middle third of diastole may be that during the early portion of diastole, the ventricles are not fully filled and cannot generate sufficient tension for reverberation. This may also be a result of tension in the chordae tendineae during rapid ventricular filling and expansion.

[0028] In one device according to an illustrative and non-limiting embodiment, the processing system 102 is configured to extract the time portions from the signal, such that each extracted time portion represents the middle third of a corresponding diastolic phase.

[0029] The processing system 102 may be implemented using one or more processor circuits, each of which may be a programmable processor circuit with appropriate software, a dedicated hardware processor such as an Application Special Purpose Integrated Circuit (ASIC), or a configurable hardware processor such as a Field Programmable Gate Array (FPGA). The memory 106 may be implemented using one or more memory circuits, each of which may be a Random Access Memory (RAM) device.

[0030] Figure 2 shows curves 210 and 211, which represent a true positive rate relative to a false positive rate. These curves 210 and 211 are related to the detection of heart failure with reduced ejection fraction (HFrEF) based on a signal indicating rotation of the cardiac-related angle, and said signal has been measured using a gyroscope. Curve 210 relates to a case in which atrial fibrillation is present, while curve 211-212 relates to a case in which atrial fibrillation is not present.

[0031] In the example cases relating to curves 210 and 211 in Figure 2, the gyroscope is a three-axis gyroscope, and the signal indicating the rotation of the heart-related angle has components indicating rotation in the x, y, and z directions of a relevant Cartesian coordinate system. The index is calculated according to Formula 1 above, and a detection result is set to indicate the presence of heart failure with reduced ejection fraction (HFrEF) in response to a situation where the index exceeds a threshold value. The true positive rate (also known as sensitivity) is the probability that an actual positive (i.e., the actual presence of HFrEF) will be detected as positive. The false positive rate is the probability that a false alarm (i.e., a positive result is detected) will occur when the true value is negative, i.e., there is no HFrEF. When the aforementioned threshold value is lowered, the true positive rate (i.e., the probability that an actual presence of HFrEF will be detected as positive) is increased, but the false positive rate (i.e., the probability of a false alarm) is also increased.

[0032] Furthermore, Figure 2 shows curves 212 and 213, which represent a true positive rate relative to a false positive rate. Curve 212 relates to a case where atrial fibrillation is present, while curve 213 relates to a case where atrial fibrillation is absent. These curves 212 and 213 are related to detecting heart failure with reduced ejection fraction (HFrEF) based on a signal indicating cardiac acceleration, which has been measured using an accelerometer. In this example, the accelerometer is a triaxial accelerometer, and the signal indicating cardiac acceleration has components indicating acceleration in the x, y, and z directions of a Cartesian coordinate system. The index is calculated in a manner corresponding to Formula 1 presented above, and a detection result is set to indicate the presence of heart failure with reduced ejection fraction (HFrEF) in response to a condition where the index exceeds a threshold value. When this threshold is lowered, the true positive rate (i.e., the probability that a real HFrEF will be detected as positive) is increased, but the false positive rate (i.e., the probability of false alarms) is also increased.

[0033] As shown in Figure 2, HFrEF detection based on cardiac-related angle rotation provides significantly better true positive rate and lower false positive rate compared to HFrEF detection based on cardiac acceleration. The measurement of cardiac-related angle rotation provides better detection results in both cases with and without atrial fibrillation.

[0034] According to one illustrative and non-limiting embodiment, a computer program includes a software module for generating information indicating heart failure with reduced ejection fraction (HFrEF) based on a signal indicating rotation of the heart-related angle. The software module includes computer-executable instructions for controlling a programmable processing system: - extracting a time portion of the heart's diastolic phase from the signal; - forming an index indicating the energy of the time portion of the diastolic phase; and - setting an output signal to indicate the presence of HFrEF based on a comparison between the index and a threshold value.

[0035] In a computer program according to an illustrative and non-limiting embodiment, the software module includes computer-executable instructions for controlling the programmable processing system to calculate the index quantity according to Formula 1 proposed above.

[0036] In a computer program according to an illustrative and non-limiting embodiment, the software module includes computer-executable instructions for controlling the programmable processing system to extract the time portion from the signal, such that each of the extracted time portions represents a middle third of a corresponding diastolic phase.

[0037] The software module may, for example, be a sub-formula or function implemented using a suitable programming language and a compiler suitable for the programmable processing system under consideration. It is worth noting that source code corresponding to a suitable programming language also represents the computer-executable software module, because the source code contains the information required to control the programmable processing system to perform the actions described above and to compile only the changes in the format of the information. Furthermore, it is possible that the programmable processing system is equipped with an interpreter, so source code implemented using a suitable programming language does not need to be compiled before execution.

[0038] A computer program product according to an illustrative and non-limiting embodiment is a computer-readable medium including, for example, a disc "CD", which is encoded with a computer program according to an embodiment of the invention.

[0039] According to an illustrative and non-limiting embodiment, a signal is encoded to carry information defining a computer program according to an embodiment of the invention.

[0040] The specific examples provided in the above description should not be construed as limiting the scope and / or availability of the appended claims. Unless otherwise expressly stated, the list and groups of examples provided in the description are not exhaustive. [Simplified Explanation of the Diagram]

[0019] Illustrative and non-limiting embodiments and their advantages are explained in more detail below with reference to the accompanying drawings, in which: [Figure 1] shows a schematic diagram of an apparatus according to an illustrative and non-limiting embodiment for generating information indicating a heart failure with reduced ejection fraction “HFrEF”, and [Figure 2] shows a curve of true positive rate relative to false positive rate, which is related to the detection of a heart failure with reduced ejection fraction “HFrEF” based on a signal indicating cardiac angular rotation measured using a gyroscope and a signal indicating cardiac acceleration measured using an accelerometer.

Claims

1. An apparatus (100) for generating information indicating heart failure with reduced ejection fraction, comprising: A signal interface (101) for receiving a signal indicating cardiac-related angle rotation, and a processing system (102) coupled to the signal interface, characterized in that the processing system is configured to: extract a time portion of the heart's diastolic phase from the signal, form an index indicating the energy of the time portion of the diastolic phase, and set an output signal of the device to indicate the presence of heart failure with reduced ejection fraction based on a comparison between the index and a threshold value.

2. The device of claim 1, wherein the device includes a sensing system (103) for generating the signal indicating rotation of the heart-related angle.

3. The device as claimed in claim 2, wherein the sensing system includes a gyroscope for measuring the heart-related angular rotation.

4. The device as claimed in claim 3, wherein the gyroscope is a Coriolis vibrating gyroscope, which includes a vibrating structure to determine the rate of rotation.

5. The device of any one of claims 1 to 4, wherein the processing system is configured to calculate the index according to the following formula: where i is an index that increases over time, N is the number of samples belonging to the time portion of the diastolic period, xi is the i-th sample of cardiac-related rotation in the x-direction of the Cartesian coordinate system (199), yi is the i-th sample of cardiac-related rotation in the y-direction of the Cartesian coordinate system, and zi is the i-th sample of cardiac-related rotation in the z-direction of the Cartesian coordinate system.

6. A computer program for controlling a programmable processing system to process a signal indicating cardiac-related angle rotation, characterized in that the computer program includes computer-executable instructions for controlling the programmable processing system to: extract a time portion of the heart's diastolic phase from the signal; form an index indicating the energy of the time portion of the diastolic phase; and set an output signal to indicate the presence of heart failure with reduced ejection fraction based on a comparison between the index and a threshold value.

7. The computer program of claim 6, wherein the computer program includes computer-executable instructions for controlling the programmable processing system to calculate the index according to the following formula: where i is an index that increases over time, N is the number of samples belonging to the time portion of the diastolic phase, xi is the i-th sample of cardiac-related rotation in the x-direction of the Cartesian coordinate system (199), yi is the i-th sample of cardiac-related rotation in the y-direction of the Cartesian coordinate system, and zi is the i-th sample of cardiac-related rotation in the z-direction of the Cartesian coordinate system.

8. A computer program product comprising a nontransitory computer-readable medium encoded with a computer program as described in any one of claims 6 to 7.

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