Method for determining electrical activity of cardiac muscle
The object of the invention is a method for determining electrical activity of cardiac muscle, characterised in that the resultant electric potential (V wyp ) forming the QRS complex in the electrocardiogram obtained during the ECG test is decomposed into partial potentials corresponding to the depolarization of specific areas (i) of the left ventricular muscle (MS).
1. A method for decomposing a resultant electric potential (Vwyp) forming a QRS complex in an electrocardiogram (ECG) into partial potentials corresponding to depolarization of specific areas (/) of a left ventricular muscle (MS), in which decomposition is carried out in such a way that on the basis of a theoretical SFHAM (single fiber based heart activity model) of electrical heart activity, mathematical functions describing changes in the partial potential values are determined, and then their parameters are selected so that superposition of the values of these functions is as close as possible to a resultant potential (Vwyp) measured during an ECG test,
wherein each of the partial potentials is described by two functions: V1,i (t) and V2,i (t), corresponding to the depolarization of a specific area of the left ventricular muscle, each of these functions has negative or positive values and one extremum, wherein a beginning of an emergence of these potentials (t0(1),i and t0(2),i) and their end (tk(1),i and tk(2),i) is considered the time at which the potential value is greater than its arbitrarily set minimum value, and a sum of the values of these potentials determines the electrical activity of the specific area of the left ventricular muscle, the method comprising:
obtaining, from the ECG test, a signal indicative of the electrical heart activity;
obtaining, from the signal, a plurality of electric potential values corresponding to measurements of the electrical heart activity, wherein the plurality of electric potential values includes the partial potential values;
calculating, using the plurality of electrical potential values obtained from the signal, an order of occurrence of extrema of the partial potential values,
wherein the order of occurrence of the extrema is determined from the theoretical SFHAM model of electrical heart activity, and positions of the extrema are determined by, using a computer:
making a series of transformations of the partial potential values for (X Y Z) coordinates in the orthogonal system, comprising rotation of the coordinates in the range (0÷90°) with respect to two selected axes by (α, β) angles,
calculating, for each rotation angle, the positions of extrema of the partial potentials for each of the (XYZ) coordinates, by using deconvolution and convolution, and a low-pass filter with parameters corresponding to the function describing the partial potentials, and then
selecting the angles for which the differences in the positions of extrema for each of the partial potentials in the XYZ system, respectively, are the smallest; and
outputting, using the order of occurrence of the extrema, an analysis of results of the ECG test.
2. The method according to claim 1 , wherein each partial potential corresponds to an interventricular septum (PR), anterior wall (SP), inferior wall (SD), lateral wall (ŚB), and posterior wall (ŚT), respectively.
3. The method according to claim 1 , an analysis of resultant potentials (QRS complexes) is made on the basis of averaged values for each lead, transformed into the orthogonal Frank system.
4. A method of determining a parameter describing resultant electrical activity of the left ventricular muscle (CM), wherein, having determined parameters of the functions V1,i (t) and V2,i (t), describing the waveforms of the partial potentials by means of the method according to claim 1 , an area under a curve of each of the partial potentials for X, Y, Z coordinates is calculated in accordance with:
A
1
,
i
=
∑
j
=
{
x
,
y
,
z
}
∫
t
0
(
1
)
,
i
t
k
(
1
)
,
i
❘
"\[LeftBracketingBar]"
V
1
,
i
,
j
❘
"\[RightBracketingBar]"
dt
A
2
,
i
=
∑
j
=
{
x
,
y
,
z
}
∫
t
0
(
2
)
,
i
t
k
(
2
)
,
i
❘
"\[LeftBracketingBar]"
V
2
,
i
,
j
❘
"\[RightBracketingBar]"
dt
where t0(1),i and t0(2),i denote respective times the partial potentials begin to appear, and tk(1),i and tk(2),i denote respective times the partial potentials stop appearing, and subsequently a parameter describing resultant electrical activity of ventricles is calculated in accordance with:
A
wyp
=
∑
j
=
{
x
,
y
,
z
}
∫
t
0
t
end
❘
"\[LeftBracketingBar]"
V
wyp
❘
"\[RightBracketingBar]"
dt
.
5. A method of determining a parameter describing resultant electrical activity of the left ventricular muscle (CM), wherein, having determined the parameters of the functions V1,i (t) and V2,i (t), describing the waveforms of the partial potentials by means of the method according to claim 1 , an area under a curve of each of the partial potentials for X, Y, Z coordinates is calculated in accordance with:
A
1
,
i
=
∑
j
=
{
x
,
y
,
z
}
∫
t
0
(
1
)
,
i
t
k
(
1
)
,
i
❘
"\[LeftBracketingBar]"
V
1
,
i
,
j
❘
"\[RightBracketingBar]"
dt
A
2
,
i
=
∑
j
=
{
x
,
y
,
z
}
∫
t
0
(
2
)
,
i
t
k
(
2
)
,
i
❘
"\[LeftBracketingBar]"
V
2
,
i
,
j
❘
"\[RightBracketingBar]"
dt
where t0(1),i and t0(2),i denote respective times the partial potentials begin to appear, and tk(1),i and tk(2),i denote respective times the partial potentials stop appearing, and subsequently normalised partial potentials (U1,i, U2,i and Uwyp) are calculated in accordance with:
U
1
,
i
=
A
1
,
i
N
wyp
N
1
,
i
A
wyp
·
100
%
;
U
2
,
i
=
A
2
,
i
N
wyp
N
2
,
i
A
wyp
·
100
%
;
U
wyp
=
A
wyp
N
wyp
·
100
%
;
wherein (N1,i, N2,i oraz Nwyp) are parameters determined for the partial potentials with normal electrical activity treated as a norm;
and further a parameter describing a change in electric charge distribution during depolarization of each myocardium area is calculated in accordance with:
J
i
=
U
2
,
i
U
1
,
i
.
6. A device configured to implement the method according to claim 1 .