JPH0856914A - System for analyzing electrocardiogram - Google Patents

Abstract

PURPOSE: To effectively detect an artifact, to reduce a pseudo positive ratio in VPC detection and to improve global analysis accuracy in the VPC detecting processing of electrocardiogram analysis. CONSTITUTION: This system is provided with a first calculation part 1 which calculates a morphological parameter for each heartbeat, a ring buffer manager 2 which registers past ten heartbeats on a ring buffer 8, a second calculation part 3 which calculates the mean value of the heartbeats in the ring buffer 8, a first decision part 4 which decides the possibility of the artifact from a change rate with the mean value, a third calculation part 5 which calculates the morphological parameter of a T wave, a second decision part 6 which decides he existence of the T wave from a calculated numeric value, and an analysis part 7 which analyzes an electrocardiogram from which the artifact is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrocardiogram analyzing method,
In particular, the present invention relates to an electrocardiogram analysis method for preventing deterioration of the VPC false positive rate due to artifacts.

[0002]

2. Description of the Related Art Before analysis, noise such as drift is removed by a band-pass filter or the like, and thereafter, VPC detection is performed on an electrocardiogram in which noise components are reduced.

[0003]

However, the conventional method cannot generate an electrocardiogram from which 100% noise has been removed, and some artifacts exist in the analyzed waveform. However, there is a drawback that an artifact is mistakenly recognized as VPC and the overall false positive rate of VPC detection is reduced.

The object of the present invention is to prevent the false positive rate of VPC detection as a whole from being lowered even if there is an artifact in the waveform to be analyzed, without causing the artifact to be erroneously regarded as VPC. It is to provide a certain electrocardiogram analysis method.

[0005]

In order to achieve the above object, an electrocardiogram analysis method according to the present invention includes a first calculation unit for calculating a morphology parameter for one real-time heartbeat to be analyzed, and a past calculation unit. A ring buffer storage unit that stores morphological parameters for 10 heartbeats, and a past 1
It has a second calculation unit that calculates the average value of the morphology parameter of zero heartbeat, and a first determination unit that determines the rate of change from the average value.

Further, a third calculation unit for calculating a morphology parameter for recognizing the shape of the T wave of one heartbeat to be analyzed and a second determination unit for recognizing the existence of the T wave by the morphology parameter. Have

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing the electrocardiogram analysis method of the present invention.

The first calculation unit 1 calculates the morphology parameter for each heartbeat. The calculation method of the morphology parameter is to calculate the perimeter and the area with respect to the data inside ± 100 mS from the peak of the R wave, and use the quotient obtained by dividing the area by the square of the perimeter as the morphology parameter.

The ring banfer manager unit 2 registers the morphology parameter m _i obtained by the first calculation unit 1 in the latest ring buffer storage unit 8 and also the morphology parameter m for 10 heartbeats. _i
Delete the oldest data and add the data to the latest heart beat morphology parameters.

The second calculator 3 calculates the average value M _ave of the morphology parameters for the past 10 heartbeats.

The first judging unit 4 compares the heartbeat to be analyzed with the average value of the morphological parameters for the past 10 heartbeats, and determines whether the rate of change between the two exceeds a certain value. To judge.

The third calculating section 5 calculates morphological parameters of the T wave portion of the heartbeat to be analyzed. The calculation method of the morphology parameter of the T wave is to search the peak of the T wave backward 200 mS behind the peak of the R wave, and obtain the morphology parameter of the waveform shape within a range of ± 100 mS before and after the peak.

The second determining unit 6 determines whether or not the morphology parameter of the T wave obtained by the third calculating unit 3 is close to the actual T wave. Further, the analysis unit 7 determines whether the heartbeat finally analyzed is a normal waveform or a VPC.

Reference numeral 8 is a ring buffer storage unit.

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

FIG. 1 is a flowchart showing an electrocardiogram analyzing method according to the present invention.

Reference numeral 1 is a first calculation unit for calculating a morphological parameter M _i for each heartbeat. The morphology parameter referred to here is calculated by the following method.

First, with respect to the input electrocardiogram waveform of one heartbeat, with the vertex of the R wave as a reference, the start point is the data of 100 mS before and the end point of the data of 100 mS after the start. The method is star
The point t and the end point are connected by a straight line, and the inclination of the straight line is obtained and set as α. Next, assuming that the number of data from the start point is i, the following calculation is performed on the data D0 _i between the start point and the end point to obtain the data D _i after the drift correction.
To (here before correction, including start point and end point is D0 ₀ ~D0 _8, after the correction to D ₀ ~D _8).

D _i = D0 _i −tan α × _i −D0 ₀ Next, the area A of the corrected data is calculated by the following equation.

[0021]

Next, with respect to the corrected data, the circumference L
Is calculated by the following formula.

[0023]

Next, A / L ^{2 is set} to the morphology parameter M
i. Generally, this parameter is a well-known parameter that can quantitatively represent a two-dimensional pattern shape.

The morphology parameter M _i obtained by the above procedure is registered in the ring buffer storage unit 8 by the ring buffer manager 2. The ring buffer referred to here is capable of storing the latest 10 morphological parameters for 10 heartbeats.
Will delete the oldest parameter and add the latest one at the same time.

Next, the second calculator 3 calculates the average value of the morphological parameters for the latest 10 heartbeats in the ring buffer, and sets it as the average value M _ave .

Next, the morphological parameter M _{i of the} heartbeat to be analyzed by the first determination unit 4 is calculated by the average value M
Compared to _ave , if the rate of change of both is greater and exceeds a certain threshold X, it goes to the third calculation unit 5. If the rate of change is small and does not exceed a certain threshold X, it is analyzed. Each branch is made to a unit 7.

The third calculation unit 5 calculates the morphology parameter M _i for the T wave by the same method as that used for obtaining the morphology parameter for the R wave in the first calculation unit 2. Then, the apex of the T wave is detected backward 200 mS behind the apex of the R wave, and a 10
A morphology parameter is calculated for the 0 ms waveform data.

The second determination unit 6 determines the morphological parameter M
_{If i} exceeds a certain threshold Z and is determined to be a T-wave-like shape, the analysis unit 7 determines that the waveform does not exceed a certain threshold Z and is not a T-wave-like shape as a VPC waveform of an electrocardiogram. If an error occurs, the analysis unit 7
The processing is terminated without being sent to.

By such a series of processing, artifacts are not input to the analysis unit 7, so that artifacts are erroneously determined as VPCs, and a decrease in diagnostic accuracy of the entire system can be suppressed.

[0031]

As described above, the present invention has
It has a ring buffer of morphological parameters for the waveform of the heartbeat, compares it with its average value, and recognizes the presence of the T-wave for the heartbeat whose rate of change is determined to be large. It is possible to effectively detect only the artifact from the input waveform with a very low probability of recognizing that the input signal is an artifact.

[Brief description of drawings]

FIG. 1 is a flowchart showing an electrocardiogram analysis method according to the present invention.

FIG. 2 is a waveform diagram showing an electrocardiographic waveform before correction.

FIG. 3 is a waveform chart showing a corrected electrocardiogram waveform.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First calculation part 2 Ring buffer manager 3 Second calculation part 4 First judgment part 5 Third calculation part 6 Second judgment part 7 Analysis part 8 Ring buffer storage part

Claims (2)

[Claims] 1. When detecting a ventricular extrasystole (hereinafter, referred to as "VPC") in an electrocardiographic analysis process, an artifact is detected by comparing a morphological parameter representing a waveform shape with an average value of past heartbeats. A method for analyzing an electrocardiogram, which comprises recognizing and thereby suppressing an error in VPC detection. 2. In the electrocardiogram analysis process, when a VPC is detected, an artifact is recognized by comparing a morphological parameter representing a waveform shape with an average value of past heartbeats, and the VPC is erroneously identified as an artifact. An electrocardiogram characterized by recognizing a T-wave shape by avoiding the above, finally recognizing an artifact only when it is determined that a T-wave does not exist, and suppressing a false positive rate of VPC detection. analysis method.