JPH02218338A - Simulator for electric phenomenon for heat - Google Patents

Abstract

PURPOSE:To obtain the time shift of a vector electrocardiogram on a display by installing a direction display means which displays the loop direction of the vector electrocardiogram on the vector electrocardiogram from the vector electrocardiogram data corresponding to the designated time by an operating means and the vector electrocardiogram data at the next time. CONSTITUTION:As for the data searching means 63 of a display output means 16, the data at the correspondence time which a display time designation operation means 62 sets is searched from the induced electrocardiogram data memory means 63-74 and vector electrocardiogram data memory means 14a-14c, and an arrow mark display position determining means 64 determines the display position and direction of an arrow mark 60 from the data. Therefore, the position (data point) which the arrow mark 60 represents shows the data obtained at the same time, and the direction of the arrow mark represents the time shift direction on each diagram, and the time correspondence between the vector electrocardiogram (front, left side, and plane views) and the induced electrocardiograms I-U6 can be performed exceedingly easily, and also the time shift direction (loop direction) can be known easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for calculating and displaying electrical phenomena of the heart within a human body, and particularly relates to an improvement in means for displaying a vector electrocardiogram.

(Prior Art) A simulator that obtains a vector electrocardiogram of the heart from a predetermined heart model through simulation is known.

The display of a vector electrocardiogram in such a simulator is
For example, it is common to display the vector electrocardiogram data in a loop on a display.

(Problem to be Solved by the Invention) By the way, when a vector electrocardiogram is expressed in a loop, each piece of data that makes up the loop moves in a fixed direction on the loop with time, but conventional simulators do not There is no means for representing the time course of vector electrocardiogram data together with time, and therefore it is inconvenient to analyze the calculation results using such vector electrocardiograms.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a simulator of cardiac electrical phenomena that allows the time course of a vector electrocardiogram to be perceived on a display in correspondence with seven times, thereby facilitating the analysis of calculation results. .

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a simulator for cardiac electrical phenomena in which a vector electrocardiogram is obtained by simulation. an electrocardiographic data storage means, a display means for displaying a vector electrocardiogram using the vector electrocardiogram data storage means, a display time designating operation means for specifying an arbitrary time that each of the data has, and based on an output signal of the operation means, Direction display means for displaying the loop direction of the vector electrocardiogram on the vector electrocardiogram from the vector electrocardiogram data corresponding to the time specified by the operating means and the vector electrocardiogram data at the next time. Features.

(Function) By displaying an arrow indicating the loop direction of the vector electrocardiogram on the vector electrocardiogram data at an arbitrary step time using the operating means, the value of the vector electrocardiogram data at an arbitrary time and the loop direction can be determined from the vector electrocardiogram. You can easily find out.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is an overall configuration diagram of a simulator according to the present invention. In the figure, reference numeral 1 is for setting various conditions for simulation, and heart model setting means 2 includes means 3 for setting a geometric model of the heart, and electricity for various cells defined by this heart geometric model setting means 3. and means 4 for setting physiological characteristics. Furthermore, 5 is a means for setting the position and angle of the heart, and 6 is a means for setting the torso.

Further, 7 indicates a calculation means for simulation, 8 a cell excitation processing means, 9 a means for storing the calculation result, and 10 further calculates on the body surface (torso) based on the calculation result. Calculate the potential and vector electrocardiogram calculation means 11
, body surface potential data storage means 13.12B body surface potential calculation means for outputting the data to the electrocardiogram calculation means 12; 13 to 15 are storage means for each data; 16 is for display output to the display means 17; It is an output means.

The cardiac geometric model setting means 2 is configured from IXJ× to three-dimensional coordinates (in this embodiment, a three-dimensional oblique coordinate system in a hexahedron) on one vertical side, one horizontal side, and on a height. A geometric model of the heart is created by assigning arbitrary blocks among the blocks to cells.

FIG. 2 shows an example of the configuration of such a geometric model setting means. The operating means 20 is for specifying the cross section and cell type of the cardiac geometric model to be changed or newly set, and the cross section can be specified by any cross section number of length l, width j, and height k. It is. The basic block storage means 21 stores the coordinates of each block in the aforementioned vertical x, horizontal J, and height. The geometric model storage means 22 stores models that have already been created or models that are currently being set, and stores, for example, cell coordinates and cell types. Section number determination means 23
determines the section number specified by the operating means. Based on the output signal of the determining means 23, the section display data output means 24 outputs the section display data based on the data of the geometric model storage means 22. Similarly, the adjacent cross section display data output means 25 outputs display data of a cross section adjacent to the cross section, and the orthogonal cross section display data output means 26
outputs display data of a cross section perpendicular to the cross section.

In addition, when specifying the cross section, any coordinate plane among the coordinates I and J can be specified, and an orthogonal cross section can also be determined thereby.

When the cross-section is displayed in this way, the necessary cell correction or addition operation is also performed by the operation means 20, and according to the output, the cell type changing means 28 to 30 are changed to a predetermined cross-section via the cell type determining means 27. Change or add cell types in .

These cell fits are the types of cells that make up the heart, such as the sinoatrial node, atrial muscle cells, atrioventricular node, bundle of His,
Legs, Purkinje fiber cells, ventricular myocardial cells, and user-definable special cells are provided. Note that the characteristics of these cells are determined by electrophysiological characteristic setting means 4, which will be described later.

With the above configuration, a predetermined cross section is displayed by the display means 32 via the output means 31.

When the above series of setting operations is completed, the modified or set data is stored again in the geometric model storage means.

Note that this display means 32 can also be used as the display means 17 shown in FIG. FIG. 3 shows the above operating procedure in the form of a flowchart, and FIG. 4 shows the display by the display means during the setting operation. In Fig. 4, 33 indicates the corrected kl cross section on the I-J plane, and 34°35 indicates the adjacent ki-1, ki+, respectively.
1 shows a cross section. Further, 36 indicates a cross section perpendicular to them. Furthermore, during each display, 37a.

37b, 37c, 37d, etc. each indicate the type of cell; 37a indicates a Purkinje fiber network cell; 37b indicates an atrial muscle or ventricular muscle cell; 37c, 37d indicates a cell in an ischemic state according to its stage. It is.

As described above, according to the present embodiment, when setting and modifying the cardiac geometric model, the surrounding area of the modified portion can be visually recognized at the same time, so that the modification, setting, etc. can be easily performed.

The electrophysiological characteristic setting means 4 provides parameters such as action potential characteristics, propagation velocity, basing time, etc. to the various cells specified by the cardiac geometric model setting means 3.

Table 1 shows such parameters, and in this example, 16
It is possible to freely change the settings of the type parameters. Further, FIG. 5 shows the correspondence between the action potential waveform and each of its parameters.

As is clear from Table 1 and FIG. 5, the action potential waveform in this example is O phase 40.1 phase 41.2 phase 42.
．． Each phase is determined by defining each of the 43 parts of the four phases as a straight line, and giving each end point of these straight lines as parameters of time and potential. Also, the membrane potential V of the three-phase 44 in the curved part
(X) is sample data S i (xi, yi) (S
l~S7) is determined by the following Lagrange interpolation polynomial.

Table 1 Parameters (n=3) As described above, in this embodiment, the action potential waveform can be defined with a small number of data, and it is possible to easily cope with reduction in the number of memories and complication of the model.

Further, according to the electrophysiological characteristic setting means, it is possible to freely set the electrophysiological characteristics such as the action potential waveform of any cell constituting the heart in cooperation with the cardiac geometric model setting means 3, and the actual A heart model that closely resembles the heart can be constructed.

Tables 2 and 3 show setting examples of each parameter, Table 2 shows the settings for Purkinje fiber network cells, and Table 3 shows the settings for ventricular myocardial cells.

Table 2 Table 3 The heart position setting means 5 and the torso setting means 6 are
As shown in the figure, a torso 50 and a heart 5 placed therein
The torso setting means 6 sets the size, shape, etc. of the torso, and the heart position setting means 5 sets the position, angle, etc. of the heart with respect to the torso.

Next, the calculation means 7 for simulation will be explained.

The excitation processing means 8 comprises an excitation propagation processing means 8a and an excitation cell time storage means 8b. At the start of the simulation, the excitation propagation processing means 8a determines the cell that starts automatic excitation based on the data from the cardiac geometric model setting means 3 and the electrophysiological characteristic setting means 4, and stores it in the cell excitation storage means. 9 and also stored in the excited cell time storage means 8b.

From the next step onwards, at each step time, cells that start to be excited by transmitting the excitement by the cells stored in the excited cell-time storage means 8b are selected based on the cell coordinates and electricity by the cardiac geometric model setting means 3. It is determined from the propagation velocity refractory period set in the physiological characteristic setting means 4, the previous excitation time stored in the cell excitation propagation processing means 9, etc., and searching for automatically excited cells set in the electrophysiological characteristic setting means 4. Find cells that newly start excitation and store them in the cell excitation storage means 9, while
The process of propagating the excitement is processed by re-memorizing it in the excitement cell-time storage means 8b and repeating the same operation thereafter.

FIG. 7 shows the above operation in the form of a flowchart. Step 1 is to set the propagation time calculated by the simulator, which is set to 3 seconds in this embodiment. Step 2.3 is the initial setting, and in this embodiment, the step time T is 31 sec%.PWF is the data stored in the excited cell time storage means 8b, and XCT is the data stored in the cell excitement time storage means 9. are shown respectively.

Then, in each step, the step time is advanced one by one, and in step 5, the end is determined. Step 6 is to search for cells that are automatically excited at time T from the electrophysiological characteristic setting means 4 and the cardiac geometric model setting means 3, and to create a PWF.
In the process of storing the data and XCT data, step 7 is to find the cell where the excitation starts by the above-mentioned propagation.
data, the process of storing it in XCT data, step 8 is P
Each figure shows the process of replacing WF data.

Incidentally, FIG. 8 shows the operation of determining whether or not cells within the propagation possible range are in the refractory period in step 7 of the excitation propagation process described above, and T pr in step 1.
e indicates the previous excitation time stored in the cell excitation storage means 9, and RF in step 2 indicates the refractory period stored in the electrophysiological characteristic setting means 4. Step 3 shows the process of storing excited cells.

As described above, according to the cell excitation propagation processing means according to the present embodiment, processing is performed by focusing only on the peripheral area of a cell that is excited at any given time, that is, a cell to which excitation may be transmitted. Since this is done, calculation time can be shortened.

Next, the body surface potential processing means 10 will be explained. FIG. 9 shows the operation of the body surface potential processing means 10. First, in step 1, the cell excitation time and electrophysiological characteristic setting means 4 of the cell excitation time storage means 9 described above are performed.
Based on the action potential waveform of , the centripetal electromotive force distribution at every other cell interval is determined, and the current dipole moment is determined.

Here, δ represents electrical conductivity, and φ represents the membrane potential of the cell.

Next, in step 2, the heart model is divided into m vertical, n horizontal, and height planes to obtain mXnXk blocks, and in order to represent each block with one dipole moment, first, the multi-dipole moment Jm Find the size of. The magnitude of this multi-dipole moment Jm is determined by the sum of the current dipole moments J1 obtained in Step 1.Next, in Step 3, the position of the current dipole moment Jl is determined in order to obtain the position of the multi-dipole moment Jm. Find the weighted average Pm. Here P
i indicates the position of cell i. Then, in step 4, the body surface potential V is determined from the multi-dipole moments determined above. Here, A' and vo are the potential generated on the body surface under infinite-like medium conditions and its normal differential as n-dimensional vectors, A and B are the nxn coefficient matrix and n-dimensional vector obtained by the boundary element method, and α is ■° The body surface area of each is shown.

According to this method of calculating the body surface potential, compared to the conventional method of calculating the body surface potential directly from the current dipole moment of each cell, the multi-dipole moment J
Since the number of m is much smaller than the number of current dipole moments, the calculation time can be significantly reduced. Moreover, in this case, the calculation accuracy is 1/1 even when the block is divided into sections of about one-third of the ventricle for each axis.
It was said that the error was within 10%.

Furthermore, in this example, the current dipole moment was determined for every other cell by focusing on the fact that the centripetal electromotive force distribution can be expressed as a continuous function, so the calculation time using the three-dimensional model was further reduced to 8 minutes. The time can be reduced to 1, resulting in a significant time reduction. In this case as well, the calculation accuracy was excellent, being within 1%, as in the case above.

The body surface potential determined as described above is stored in the body surface potential data storage means 13, and the 12-lead electrocardiogram data calculation means 12 calculates 12-lead electrocardiogram data based on the body surface potential and the storage means 15 Store in. Further, the vector electrocardiogram data calculation means 11 calculates vector electrocardiogram data from the value of the multi-dipole moment and stores the data in the storage means 14.

The display output means 16 displays a vector electrocardiogram on the display means 17 based on the data stored in the respective storage means 13-15.
It outputs and displays body surface electrograms, 12-lead electrocardiograms, etc.

In this embodiment, the display output means 16 can output a vector electrocardiogram and a 12-lead electrocardiogram while displaying their time correspondence on the same screen 61.

FIG. 10 shows a 12-lead electrocardiogram (1-U6) and a vector electrocardiogram (front,
Left side, plane) shown. In each diagram, there is an arrow 6 pointing to the electrocardiogram.
0 is displayed. The position where this arrow is displayed (
Data points) indicate data obtained at the same time, and the direction of the arrow indicates the direction of time progression in each figure.

Therefore, according to such a display, vector electrocardiogram and 12
The time correspondence of the lead electrocardiogram can be very easily performed, and the time transition direction (loop direction of the vector electrocardiogram) can also be easily known, making it easy to understand each diagram.

FIG. 11 shows the configuration of the display output means for displaying the above-mentioned display, and shows the operation means 6 for determining the position of the arrow, that is, the corresponding time.
2. This corresponding time data is stored in the 12-lead electrocardiogram data storage means 63 to 74 and the vector electrocardiogram data storage means 14.
It is provided with data search means 63 for searching from a to 14c, and arrow display position determining means 64 for determining the display position and direction of the arrow from these data.

Incidentally, FIG. 12 is a flowchart showing an example of the above operation.

An example of the results of simulation performed by the simulator according to the present invention as described above is shown below.

FIGS. 13 and 14 show a 12-lead electrocardiogram (I-06) and a vector electrocardiogram, which are the results of simulations for a normal heart model and a heart model with apical hypertrophic myocardial disease, respectively. Comparing the two, in the case of the heart model of apical hypertrophic myocardial disease, the 12-lead electrocardiogram v3 *
Giant negative T waves 65a and 65b appear in lead V4, respectively. This is the 15th test based on measurement data from clinical experiments.
In the V3°v4 lead in the figure, the giant negative T wave 66
a.

66b is observed, which supports the reliability of this simulator.

In addition, FIG. 16 shows an example of the body surface potential waveform as a result of the calculation. Display numbers 1 to 12 are numbers in the torso direction on the torso in FIG. 6, and display numbers 1 to 6 are numbers in the torso direction in FIG. They are shown on the torso in correspondence with the numbers in the height direction of the torso. Also, in FIG. 6, R and L.

F, Vl to Va each indicate the measurement position of the 12-lead electrocardiogram.

(Effects of the Invention) As is clear from the above description, according to the present invention, an arrow indicating the loop direction of the vector electrocardiogram is displayed on data at an arbitrary step time of the vector electrocardiogram using the operation means. The value of the vector electrocardiogram data at the time of and the loop direction thereof can be easily known while viewing the vector electrocardiogram, and the vector electrocardiogram can be easily and quickly understood.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a simulator according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the configuration of a cardiac geometric model setting means, FIG. 3 is a flowchart showing a procedure for setting a geometric model, and FIG. Figure 5 is a diagram showing the display screen when setting the model, Figure 5 is a diagram showing the action potential waveform, Figure 6 is a diagram showing the torso and heart, Figure 7 is a flowchart showing the procedure of excitation propagation processing,
Figure 8 is a flowchart showing the determination of the refractory period, Figure 9 is a flowchart showing the procedure for determining body surface potential, and Figure 10 is a flowchart showing the procedure for determining the body surface potential.
The figure shows a display example of a 12-lead electrocardiogram and a vector electrocardiogram, Fig. 11 shows a display output means, Fig. 12 is a flowchart showing the procedure of arrow display, and Fig. 13 shows a 12-lead electrocardiogram and vectors in a normal model. Figure 14 is a diagram showing an electrocardiogram, and Figure 14 is a diagram showing a 12-lead electrocardiogram and vector electrocardiogram based on a heart model of apical hypertrophic myocardial disease. Figure 15 is a diagram showing a 12-lead electrocardiogram of clinical measurement results from a patient with the same disease. FIG. 16 is a diagram showing a body surface potential waveform. In the drawing, 2 is a heart model setting means, 3 is a heart geometric model setting means, 4 is an electrophysiological characteristic setting means, 5 is a heart position setting means,
6 is a torso setting means, 8 is an excitement transmission mIA embedding means, 8b is an excitement cell time storage means, 9 is an excitement time storage means, 10 is a body surface potential processing means, 13 is a body surface potential data storage means,
15 is an electrocardiogram data storage means dedicated to the 12th episode, 16 is a display output means, 17 is a display means, 20 is an operation means, 50 is a torso, 60 is an arrow, 62 is a display time designation operation means, 64 is an arrow display position/direction determination means (direction display means).

Claims (1)

[Scope of Claims] A simulator for cardiac electrical phenomena in which a vector electrocardiogram is obtained by simulation, comprising: vector electrocardiogram data storage means for storing data for each time of the vector electrocardiogram; a display means for displaying a vector electrocardiogram; a display time specifying operation means for specifying an arbitrary time included in each of the data; and a vector electrocardiogram corresponding to a time specified by the operation means based on an output signal of the operation means. A simulator of cardiac electrical phenomena, comprising direction display means for displaying a loop direction of a vector electrocardiogram on the vector electrocardiogram from data and vector electrocardiogram data at the next time.