JPS62217936A - Apparatus for analyzing electrocardiograph - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for accurately estimating the potential of each part of the epicardial surface, for example, for a heart disease patient, by simply measuring the potential of each part of the crosspiece surface. The present invention relates to an electrocardiogram analysis device for fixing the affected area and the cause of the disease.

[Conventional technology]

Traditionally, Roger C. Ba.
1 IE Transactions on Biomedical Engineering, P.M.E., Volume 24, No. 1, January 1977 issue” (
”IEEE Transactions on Bio
Medical Engineering, vol, BM
E-24, AI, January 1977”)
As shown in the paper published in , the electrical phenomenon between the epicardial surface and the body surface is formulated as an integral equation, and this is discretized by a triangular network covering the epicardial surface and the body surface, and the simultaneous -
By solving the following equation, the potential distribution on the body surface was determined from the potential distribution on the epicardial surface.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, it is possible to determine the potential distribution on the body surface from the potential distribution on the epicardial surface, but there is no formulation for determining the potential distribution on the epicardial surface from the measured body surface potential, which is clinically important. Not yet.

In addition, since the discretization network that covers the body surface and epicardial surface is limited to a triangular network, curved surface elements used in the boundary element method, 2, which more accurately capture complex shapes such as the body surface, Since the next element is not used, the accuracy of calculation is considered to be lower.

An object of the present invention is to provide an electrocardiogram analysis device that can support the identification of abnormal areas in the epicardial membrane by predicting the electric potential at each part of the epicardial surface and its temporal change. .

a shape input unit that inputs data regarding the shape and relative position of the surface; a boundary element mesh generation unit that generates a boundary element mesh of the body surface and epicardial surface based on the data input from the shape input unit; A matrix element calculation unit based on the boundary element method based on the output data of the shape input unit and the boundary element mesh generation unit, and an LU separation color and body that performs LU decomposition of the matrix based on the output of the matrix element calculation unit. an input section that inputs the potential observed at the electrode on the surface; a matrix multiplication section that performs matrix and vector multiplication based on the output data of the matrix element calculation section and the output data of the input section; and the matrix multiplication section. a forward substitution unit that performs forward substitution based on the output of the forward substitution unit and the LU separation color output; a backward substitution unit that performs backward substitution based on the output of the forward substitution unit and the LU separation color output; An electrocardiogram analysis device comprising a backward substitution section and an output section that outputs data including predicted values of potentials at various parts of the epicardial surface based on the outputs of the shape input section and the boundary element mesh generation section. can get.

[Principle of the invention]

Assuming that the dielectric constant ε is constant and there is no charge in the body B surrounded by the epicardial surface H and body surface T in Figure 2, the shape and relative position of the epicardial surface H and body surface T are known. It is assumed that

Considering the above assumption and referring to Figure 3, the potential ψ(
xyy+z) is a three-dimensional Laplace equation % Formula % If we set V = ψ and u = ψ in Green's formula, (1) t (2) ,
From (3), /-9+ (x) δ (x, y) dV (x) However, the unit normal vector n is taken to be directed outward from the body at the body surface T, and directed toward the inside of the heart at the epicardial surface H.

(3) Therefore, when y is on the body surface T or the epicardial surface H, (
5) becomes (furnace y+ (7). However, ω (branch) is the solid angle looking into the body B at point y, and yy
When y is on the body surface T, (7) becomes (xy〆y), and when y is on the epicardial surface H, (x, I〆y). However, ψ7, 91□, etc. are on the body surface T, respectively.

A mesothesis each consisting of n elements is placed on the epicardial surface H.

For example, a triangular element as shown in Figure 4 is provided, the representative point (for example) of element i is the center of gravity yi, the area of the element is ΔSi, and the value of ψ is ψ1 within the element. Considering, (9) and (10) are approximately (11
), (12).

In other words, yTl (i=1 to n) on the body surface T is null to 3'+rt (i=1 to n) on the epicardial surface H. However, Ci”C(7i)+rji=xJ-74+rj
4 =, (11) and (12) are (i=1~n) (
16) (i=1~n)
It can be expressed as (17).

where ATT = 07'N), BTT = (bAT
),,, (nxn matrix) ATT = (a'!'Q
) l BTII = (b”I) (18) IJ
Letting IJ (16), (
17) is ψ・＝”“ψ・+”“q・10″“ψ・+””′q・(1
゜) and put (19) and (20) together 4. Solving (21) with respect to ψ□ + qH on the epicardial surface, since the body surface is considered to be an insulating boundary, that is, qT = 0
Since, we obtain (22).

Therefore, if we create a mesh in which triangular elements correspond to each electrode provided on the body surface T, y, (t=x~n), the body surface y
Potential ψT observed at Tl (i=1~n), (l=1~
n) Using (24), the potential ψH1 (!=1 to n) at each part of the epicardial surface H can be determined.

Here ATT, ATH, AHT, AHH, BTH, B
HH is (14).

As can be seen from (15), the body surface T and the epicardial surface H are determined, and the mesh on T and the mesh on H, which are located at the position of the electrode on the body surface, are determined.

Therefore, for example, if we use the cloud method to decompose the product of the lower triangular matrix and the upper triangular matrix U as follows, we can further perform forward substitution (L) and backward substitution (U) of the body surface potential at each time. , the electric potential at each part of the epicardial surface H at that time and, if necessary, the electric field -qH in the normal direction to the surface H can be determined with a calculation amount on the order of n2.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, the potential ψ measured at electrode 1 on the body surface and each part
Tl l %2 + .

The matrix multiplication unit 4 inputs a 2nc vector to the forward substitution unit 5 for the input 9JT. The forward substitution unit 5 performs forward substitution for ψ and inputs L-1ψ to the backward substitution unit 6. The backward substitution unit 6 performs backward substitution for Lf.

In the preprocessing section 8, before the solving section 3 operates, the body surface,
Information such as epicardial surfaces, their relative positions, and electrode positions on the body surface is sent to the shape input section 9 and the boundary element mesh generation section 1.
It is input to 0. The boundary element mesh generation unit 10 generates a mesh of boundary elements on a model of the body surface and the corresponding epicardial surface based on the electrode positions on the body surface, and generates data such as three-dimensional coordinates of each element. In addition, matrix element calculation unit 11
Enter. In the matrix element calculation unit 11, each boundary element j,
Numerical integration within each element is performed based on the vector rJi between i, the outward unit normal vector n1 of each element, the coefficient Ct, etc., and nxn matrices A and A are obtained.

A HT , AI (H, BTH, Bt (see formulas (14) to (18) to generate H etc.) Among them, ATT ,
Input AHT to the matrix multiplier 4 (see formula (24))
A TH, Al1) (, B TH, B HH are input to the LU decomposition unit 12. The LU decomposition unit 12 decomposes the A matrix into LU using the Loud method. (25) Weapon f! A), lower triangular matrix is input to the forward substitution unit 5, and the upper triangular matrix U is input to the backward substitution unit 6.
Enter.

The output unit 7 includes a shape input unit 9 and a boundary mesh generation unit 10
Based on the data input from , the potential at each part of the epicardial surface at each time is output and displayed or recorded.

〔Effect of the invention〕

As described above, the present invention uses only the observed values of the potentials of various parts of the body surface and uses simple calculations to quickly predict the potentials of each part of the epicardial surface at each time point. It helps to identify the target more accurately and easily than traditional methods.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2, FIG. 3, and FIG. 4 are diagrams showing models of the body surface and epicardial surface for detailed explanation of the present invention. ■... Electrodes on the body surface, 2... Input section,
3... Conversion section, 4... Matrix multiplication section, 5
...Forward substitution section, 6...Backward substitution section,
7... Output section, 8... Preprocessing section, 9.
... shape input section, 10 ... boundary element mesh generation section, 11 ... matrix element calculation section, 12.
...LU minutes Yij Figure') f5z diagram ¥J3 times

Claims (1)

[Claims] a shape input section for inputting data regarding the shape of the body surface, the position of the electrode on the body surface, the shape and relative position of the epicardial surface;
A boundary element mesh generation unit that generates a boundary element mesh of the body surface and epicardial surface based on data input from the shape input unit, and output data of the shape input unit and the boundary element mesh generation unit. There is a matrix element calculation unit that calculates matrix elements using the boundary element method, an LU decomposition unit that performs LU decomposition of the matrix based on the output of the matrix element calculation unit, and input potentials observed at electrodes on the body surface. a matrix multiplication section that multiplies a matrix and a vector based on the output data of the matrix element calculation section and the output data of the input section; a forward substitution unit that performs forward substitution based on the source; a backward substitution unit that performs backward substitution based on the output of the forward substitution unit and the output of the LU decomposition unit; the backward substitution unit, the shape input unit, and the boundary. An electrocardiogram analysis device comprising an output section that outputs data including predicted values of potentials at various parts of the epicardial surface based on the output of the element mesh generation section.