JP2019129954A - Atrial fibrillation detection system - Google Patents

Abstract

To provide an atrial fibrillation detection system capable of suppressing detection of false positive by simply and reliably excluding an irregular beat interval not derived from heart beats.SOLUTION: An atrial fibrillation detection system 1 for detecting the presence or absence of an atrial fibrillation of a subject comprises: beat interval measuring means 2 for measuring beating intervals of the heart of the subject; irregular beat interval excluding means 3 for excluding irregular beat intervals not derived from the beat of the heart of the subject from beat interval data measured by the beat interval measuring means 2; determination means 4 for determining whether or not atrial fibrillation has occurred by using post-exclusion data obtained by excluding irregular beat intervals from the beat interval data by the irregular beat interval excluding means 3; and display means 5 for displaying a determination result obtained by the determination means 4.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an atrial fibrillation detection system.

  Atrial fibrillation is a heart disease in which the atrium shakes finely, and blood stagnates in the atrium, making it easy to form a thrombus. This thrombus is suddenly carried to the brain and there is a risk of developing cerebral infarction.

  According to an epidemiological study of the Japanese Circulation Society, the prevalence of atrial fibrillation is 0.1% in the 40s, 0.6% in the 50s, 0.9% in the 60s, and 2.7% in the 70s and above. According to the Framingham Study, the prevalence of men aged 65 to 84 was 3.2% in 1970 but increased to 9.1% in 1998.

  Due to the large size of the thrombus that occurs in the atria due to atrial fibrillation, it blocks the thick blood vessels in the brain, leaving severe sequelae. For this reason, treatment costs and caregivers are required as long as the patient is alive, and there is a great social and economic loss.

  However, since treatment is possible if atrial fibrillation can be found, the possibility of causing a serious disease such as cerebral infarction can be extremely reduced.

  Treatment to prevent cerebral infarction needs to be continued throughout life, but there is the use of anticoagulants. In addition, there is ablation as a method aiming for complete cure, and it is said that 79.5% is completely cured if early atrial fibrillation. It is early atrial fibrillation that can be completely cured by ablation, but atrial fibrillation at this time is called paroxysmal atrial fibrillation, and it can be found by a general electrocardiogram of about 30 seconds performed in hospitals and medical examinations It is rare.

  According to the STROKESTOP Study, it is said that most patients will be found if ECG is taken intermittently for 15 consecutive days, and 60% will be found in 5 days. That is, it can be said that measuring an electrocardiogram continuously for several days is effective for detecting paroxysmal atrial fibrillation. For example, in a medical examination, if an electrocardiogram is measured continuously for several days, paroxysmal atrial fibrillation can be detected, which has an effect of suppressing social and economic loss due to cerebral infarction. However, the preparation of equipment for examining hundreds of people at the same time, such as a medical examination, and the analysis of an electrocardiogram for a long time are expensive and impractical.

  Therefore, the applicant has proposed a system for detecting atrial fibrillation only from the heart beat interval (see Patent Document 1). This system detects atrial fibrillation only from the pulse interval, so even if you measure the pulse interval over several days, the amount of data is less than the ECG and it is cheaper than analyzing the ECG . In addition, since the device that measures only the pulse interval can be configured cheaper than the Holter electrocardiograph, the combination of the device that measures the heart beat interval and the system that detects atrial fibrillation only from the pulse interval is Suitable for medical examination.

  As described above, in order to detect paroxysmal atrial fibrillation, a pulse interval of several days is necessary, and the pulse interval must be measured in the daily life of the subject. In everyday life, it is natural to move the body, but even when the body is moved, the polarization of the electrodes used to acquire the electrocardiogram signal changes (not derived from the so-called articulation of the heartbeat) Signal source.). Since an apparatus that measures only the beat interval cannot distinguish between an electrocardiogram and an artifact, if there is an artifact, the beat interval cannot be measured correctly. When such a beat interval including artifacts is applied to the atrial fibrillation detection system disclosed in Patent Document 1, a false positive (false detection) is caused.

Japanese Patent No. 6150825

  The present invention has been made in view of the above situation, and practical atrial fibrillation that can easily and reliably exclude false beat intervals not derived from heart beats and suppress false positive detection. A detection system is provided.

  The gist of the present invention will be described with reference to the accompanying drawings.

  An atrial fibrillation detection system 1 for detecting the presence or absence of a subject's atrial fibrillation, a pulse interval measuring means 2 for measuring the heart beat interval of the subject, and a pulse interval measuring means 2 Incorrect pulse interval exclusion means 3 that excludes an incorrect pulse interval that does not originate from the heart beat of the subject from the pulse interval data measured in step 3, and the incorrect pulse interval excluded from the pulse interval data Determining means 4 for determining whether or not atrial fibrillation has occurred using the excluded data excluding the incorrect beat interval by means 3, and display means 5 for displaying the determination result obtained by the determining means 4 The present invention relates to an atrial fibrillation detection system characterized by comprising:

  2. The atrial fibrillation detection system according to claim 1, wherein the irregular pulsation interval excluding means 3 uses the pulsation interval smaller than a time A set based on a QT interval of a healthy person from the pulsation interval data. And an atrial fibrillation detection system that is configured to exclude a pulsation interval greater than a time B set based on a pulsation interval during bradycardia.

  3. The atrial fibrillation detection system according to claim 2, wherein the irregular beat interval exclusion means 3 excludes the previous NB beat and the subsequent NF beat having a beat interval smaller than the time A from the beat interval data. In addition, the present invention relates to an atrial fibrillation detection system configured to exclude the previous MB beat and the subsequent MF beat having a beat interval larger than the time B.

  Further, in the atrial fibrillation detection system according to any one of claims 2 and 3, the pulsation interval measuring means 2 is more than the time B when the pulsation interval of the subject's heart cannot be measured. The present invention relates to an atrial fibrillation detection system configured to output a large constant beat interval as a measurement value.

  Further, in the atrial fibrillation detection system according to any one of claims 1 to 4, the determination unit 4 calculates a normalized pulsation interval DR (N) represented by the following expression (1) from the post-exclusion data. Normalized beat interval calculation means for calculating the number of abnormal normalized beat intervals whose absolute value exceeds a normal beat interval threshold value among a predetermined number of consecutive normalized beat intervals DR (N) The abnormal normalized pulsation interval integrating means for integrating the integrated number of abnormal normalized pulsation intervals with a normal integrated number threshold, and the integrated number of abnormal normalized pulsation intervals exceeds the normal integrated number threshold. The atrial fibrillation detection system is characterized by comprising atrial fibrillation determination means for determining that atrial fibrillation has occurred.

ここで、Ｎは１より大きい整数、添え字ｎは時系列を表し、
ｎはｎ＋１に対して過去を意味する。

Here, N is an integer greater than 1, the subscript n represents a time series,
n means the past with respect to n + 1.

  Since the present invention is configured as described above, it becomes a practical atrial fibrillation detection system capable of suppressing false positive detection by simply and reliably excluding an irregular pulsation interval that does not originate from the pulsation of the heart.

It is explanatory drawing which shows the pulsation interval which does not contain an artifact. It is explanatory drawing which shows the beat interval containing an artifact. It is explanatory drawing which shows the beat interval containing an artifact. It is a structure schematic explanatory drawing of a present Example.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

  From the beat interval data obtained by the beat interval measuring means 2, an incorrect beat interval not derived from the heart beat, that is, a beat interval derived from myoelectricity or body movement can be excluded. Since it is determined whether or not atrial fibrillation is performed using pulsation interval data (data after exclusion) that does not include a pulsation interval, detection of false positives can be suppressed as much as possible.

  Specific embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 4, the present embodiment is an atrial fibrillation detection system 1 for detecting the presence or absence of a subject's atrial fibrillation, which measures the pulsation interval of the subject's heart. An interval measuring means 2, and an irregular pulse interval excluding means 3 for excluding an irregular pulse interval not derived from the heart beat of the subject from the beat interval data measured by the beat interval measuring means 2. Determining means 4 for determining whether or not atrial fibrillation has occurred using the post-exclusion data obtained by excluding the incorrect pulse interval from the beat interval data by the incorrect pulse interval excluding means 3; Display means 5 for displaying the determination result obtained in 4.

  Specifically, the pulsation interval measuring means 2 is provided in a sensor for measuring the pulsation interval, and the irregular pulsation interval excluding means 3, the determining means 4, and the (determination result) display means 5 are wired or wireless to the sensor. It is provided in the analyzer connected with. The analyzer is an electronic computer or measuring instrument that performs a series of operations, comparisons, and displays, and a dedicated device, a personal computer, a tablet computer, a smartphone, a mobile phone, or the like having the above-described means can be employed.

  Each part will be specifically described.

  The pulsation interval measuring means 2 uses, for example, an interval between one R wave and another R wave adjacent thereto from an electrocardiogram based on a change in voltage obtained from an electrode using a microcomputer or the like, or one S The pulsation interval is measured from the interval between the wave and another S wave adjacent thereto. The sensor can be configured to be affixed to the body surface of the subject via an electrode, for example. The pulsation interval measuring means 2 may be configured to measure a pulse wave from infrared reflected light and measure the pulsation interval from the peak interval. Alternatively, the interval between pulsations may be measured by capturing heart sounds and pulse sounds and electrically processing the heart sounds and / or pulse sounds.

  The irregular pulsation interval exclusion means 3 processes pulsation interval data (a pulsation interval group consisting of a large number of pulsation intervals) transmitted from the sensor (transmission means) to the analyzer. Incorrect pulsation intervals are sequentially thinned out from the transmitted pulsation interval data and sent to the determination means 4 at the subsequent stage.

  In the present embodiment, the irregular pulsation interval excluding means 3 is based on the pulsation interval smaller than the time A set based on the QT interval of the healthy person from the pulsation interval data and the pulsation interval during bradycardia. The pulsation interval larger than the set time B is excluded.

  Specifically, the time A is preferably 350 ms or more and 470 ms or less, and the time B is preferably 2000 ms or more.

  Further, the irregular pulsation interval exclusion means 3 further excludes NB beats and NF beats after pulsation intervals smaller than the time A from the pulsation interval data, and is larger than the time B. The data after exclusion is obtained by excluding the previous MB beat and the subsequent MF beat.

  The reason why the irregular beat interval exclusion means 3 is configured as described above will be described in detail below.

  In a system that detects atrial fibrillation from the heart beat interval, if there is an artifact in the electrocardiogram, an incorrect heart beat interval that is not derived from the heart is measured, which causes false positives.

  FIG. 1 is a beat interval that does not include an artifact of an atrial fibrillation patient, and FIGS. 2 and 3 are beat intervals that include an artifact of an atrial fibrillation patient. In both cases, the horizontal axis represents the number of beats of the heart, and the vertical axis represents the beat interval.

  In the portion X in FIG. 2, a very short pulsation interval is measured. These are shorter than the average QT interval (ventricular excitement time) of healthy subjects (those without heart disease). Therefore, it is an artifact (incorrect pulsation interval) derived from myoelectricity or body movement.

  In order to exclude an incorrect beat interval of the X portion, a beat interval smaller than the time A indicated by a broken line may be excluded. In addition, assuming that there is a wide range of influence of artifacts due to myoelectricity, if the previous NB beat and the subsequent NF beat with a beat interval smaller than time A are further excluded, a more incorrect beat interval is surely excluded. it can.

  Time A is for each healthy person by gender and age group (for example, males in their teens, females in their teens, males in their 20s, females in their 20s, males in their 30s, females in their 30s, males in their 40s, females in their 50s) , Women in their 50s, men in their 60s and over, and women in their 60s and over), etc. For example, the average value of the QT interval itself may be the time A, and a value smaller than the predetermined time may be the time A.

  In general, since the QT interval of a healthy person is larger than 350 ms and smaller than 470 ms, it is preferable that the time A is 350 ms or more and 470 ms or less (set appropriately according to the sex and age of the subject). In FIG. 2, it is set to 350 ms. Depending on the characteristics of the pulsation interval measuring means 2, the thresholds NB and NF are preferably 5 or more and 60 or less. In FIG. 2, NB is 29 and NF is 25.

  Further, a very large pulsation interval is measured in the Y portion of FIG. These are less than 30 beats per minute in terms of heart rate, and are far below the apparent bradycardia (heart rate during bradycardia), so it can be said to be an incorrect pulsation interval. This is because the state in which the pulsation interval measuring means 2 cannot measure the pulsation interval of the subject continues intermittently due to the body movement of the subject or inadequate handling of the sensor (pulsation interval measuring means 2). Conceivable.

  In order to exclude an incorrect pulsation interval in the Y portion, a pulsation interval greater than the time B indicated by the broken line may be excluded. Further, assuming that there is a wide range of influence as described above, and further excluding the previous MB beat and the subsequent MF beat of the beat interval larger than the time B, it is possible to reliably exclude an incorrect beat interval.

  Although depending on the characteristics of the pulsation interval measuring means 2, the threshold values MB and MF are preferably 10 or more and 100 or less. In FIG. 3, it is 50 for both. Since less than 30 beats per minute falls below the apparent bradycardia, on the basis of this, a value larger than 2000 ms is appropriate for the time B. In FIG. 3, it is 3000 ms.

  The pulsation interval measuring means 2 may be configured to output a constant pulsation interval larger than the time B as a measurement value when the pulsation interval of the subject cannot be measured. In this case, it is possible to exclude an inaccurate pulsation interval and to inform the subject of inadequate handling of the sensor (measurement means 2 between pulsations) (eg, the electrode is not in close contact with the body surface of the subject).

  For example, when the irregular pulsation interval excluding means 3 continuously detects a certain pulsation interval larger than the time B for a predetermined time continuously, the display means 5 is displayed to indicate that it cannot be normally measured. By doing so, it becomes possible to inform the subject of the handling failure.

  The determination means 4 can be applied to any method for determining atrial fibrillation using the beat interval. In this embodiment, the determination means 4 disclosed in Patent Document 1 is configured to determine whether or not atrial fibrillation has occurred.

Specifically, the determination means 4, from unauthorized beat intervals excluded beat interval data (data after excluding), the time series of beating gap of the heart by the following formula when the R _n (1) A normalized pulsation interval calculation means for calculating the normalized pulsation interval DR (N) represented, and an absolute value of the normalized pulsation interval DR (N) of a predetermined number of consecutive values is a normal pulsation interval An abnormal normalized pulsation interval integrating means for integrating the number of abnormal normalized pulsation intervals exceeding a threshold value, and comparing the integrated number of the abnormal normalized pulsation intervals with a normal integrated number threshold, and said abnormal normalized pulsation The atrial fibrillation determination means determines that atrial fibrillation has occurred when the cumulative number of intervals exceeds the normal cumulative number threshold.

ここで、Ｎは１より大きい整数、添え字ｎは時系列を表し、
ｎはｎ＋１に対して過去を意味する。

Here, N is an integer greater than 1, the subscript n represents a time series,
n means the past with respect to n + 1.

  That is, in this embodiment, after the beat interval is measured by the beat interval measuring means 2 and beat interval data is obtained, before the processing by the normalized beat interval calculating means, the incorrect beat interval excluding means 3 is used. Data after exclusion is obtained by excluding an incorrect beat interval that does not originate from the heart beat of the subject from the beat interval data.

  As the display means 5, a display that displays characters, images, and the like can be used. In this case, the time series of the beat intervals can be displayed in a graph together with the time, and it can be displayed in an easy-to-understand manner at which beat interval the atrial fibrillation occurs. Light, sound, and vibration can also be used. In this case, the occurrence of atrial fibrillation can be immediately notified. For example, an LED can be used as light, a buzzer (speaker) or an earphone can be used as sound, and a motor (vibrator) can be used as vibration.

  Since the present embodiment is configured as described above, the beat interval data obtained by the beat interval measuring means 2 is used to calculate an incorrect beat interval not derived from the heart beat, that is, a beat derived from myoelectricity or body movement. The movement interval can be excluded, and it can be determined whether or not the atrial fibrillation is performed using the beat interval data (data after exclusion) that does not include the incorrect beat interval. Therefore, it is possible to detect atrial fibrillation more reliably using the beat interval derived from the beat of the heart, and to suppress false positive detection as much as possible.

  Therefore, the present embodiment is a practical one that can easily and surely exclude false beat intervals not derived from heart beats and suppress false positive detection.

  An experimental example supporting the effect of the present embodiment will be described.

  An atrial fibrillation detection system in which the beat interval of one healthy person is measured by the beat interval measuring means 2 for 24 hours, and the irregular beat interval exclusion means 3 is not included in the measured 24-hour beat interval data (conventional example) Table 1 shows the results of applying an atrial fibrillation detection system (an experimental example according to this example) including the irregular pulse interval exclusion means 3). Here, the parameters of the irregular beat interval excluding means 3 are set to time A = 360 ms, time B = 3000 ms, and NB = NF = MB = MF = 25 beats. The determination means 4 uses the determination method in the atrial fibrillation detection system of Patent Document 1 to set 20 consecutive normalized pulsation intervals DR (2) as one interval, and the absolute value in each interval is a normal pulsation interval threshold value. Atrial fibrillation was determined when the number of abnormal normalized beat intervals exceeding 0.1 exceeded 6.

  Since the test subject is a healthy person, when the presence of atrial fibrillation is positive, it is negative in all sections where atrial fibrillation is determined. In the conventional example, the true negative was 79,048 sections and the false positive was 6,065 sections, whereas in the experimental example, the true negative was 63,018 sections and the false positive was 630 sections. That is, the specificity is improved to 99.0% in the experimental example compared to 92.9% in the conventional example.

  Here, the specificity is an index represented by (number of true negative sections / (number of true negative sections + number of false positive sections)) × 100%.

  From the above, it was confirmed that the detection of false positives can be suppressed according to this example.

DESCRIPTION OF SYMBOLS 1 Atrial fibrillation detection system 2 Pulsation interval measurement means 3 Illegal pulsation interval exclusion means 4 Judgment means 5 Display means

Claims (5)

  An atrial fibrillation detection system for detecting the presence or absence of a subject's atrial fibrillation, the pulse interval measuring means for measuring the heart beat interval of the subject, and the pulse interval measuring means. Illegal pulse interval excluding means for excluding illegal pulse intervals not derived from the heart beat of the subject from the beat interval data, and illegal pulse interval excluding means from the beat interval data by the illegal pulse interval excluding means. It has a determination means for determining whether atrial fibrillation has occurred using post-exclusion data excluding the beat interval, and a display means for displaying the determination result obtained by this determination means. Atrial fibrillation detection system.   2. The atrial fibrillation detection system according to claim 1, wherein the irregular pulsation interval excluding means uses the pulsation interval and bradycardia smaller than a time A set based on a QT interval of a healthy person from the pulsation interval data. An atrial fibrillation detection system configured to exclude a pulsation interval greater than a time B set based on the pulsation interval of time.   3. The atrial fibrillation detection system according to claim 2, wherein the irregular pulsation interval excluding means excludes NB beats and NF beats after pulsation intervals smaller than the time A from the pulsation interval data, and The atrial fibrillation detection system is configured to exclude the previous MB beat and the later MF beat of the beat interval larger than the time B.   4. The atrial fibrillation detection system according to claim 2, wherein the pulsation interval measuring means is a constant greater than the time B when the pulsation interval of the subject's heart cannot be measured. An atrial fibrillation detection system configured to output a beat interval as a measurement value. 5. The atrial fibrillation detection system according to claim 1, wherein the determination unit calculates a normalized pulsation interval DR (N) represented by the following expression (1) from the post-exclusion data. Normalized pulsation interval calculation means and the number of abnormal normalized pulsation intervals whose absolute value exceeds a normal pulsation interval threshold among a predetermined number of consecutive normalized pulsation intervals DR (N) are integrated. When the abnormal normalized pulsation interval integration means compares the integrated number of the abnormal normalized pulsation interval with the normal integration number threshold, and the integrated number of the abnormal normalized pulsation interval exceeds the normal integration number threshold An atrial fibrillation detection system comprising: atrial fibrillation determination means for determining that atrial fibrillation has occurred.

Here, N is an integer greater than 1, the subscript n represents a time series,
n means the past with respect to n + 1.

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