RU2780122C1 - Method for controlling an ablation apparatus for biological tissues (2 variants) - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions relates to medicine, namely, to methods for controlling a surgical instrument for biological tissue ablation. In implementation of the method, the bipolar ablation apparatus is connected to a power source. The ablation apparatus has two electrodes. The two electrodes of the ablation instrument are put in contact with the surface of the tissue so that the treated tissue is located between the electrodes. Voltage is applied to the electrodes of the instrument. The impedance Z of the tissue and the rate of change therein dZ/dt, the power W and the rate of change therein dW/dt are constantly measured. The energy E given to the load is calculated for the entire ablation process. The initial conditions are verified. The treated tissue is heated at a given speed until the value of the set value of reduction in the impedance is reached, equal to 0.7–0.8 of the initial value of impedance. The values of the total energy Ep required to achieve transmurality of the tissue and the maximum permissible power Wmax required to achieve transmurality are estimated. The transition to the mode of maintaining a constant level of impedance is made. The achievement of transmurality is assessed based on determining the value of power W exceeding Wmax, or based on the amount of energy E given to the load exceeding the value of the total energy Ep required to achieve transmurality of the tissue, or after the set time passes after making the transition to the mode of maintaining a constant level of impedance. In order to estimate the total energy Ep and the maximum power Wmax required to achieve transmurality, additionally, after verifying the initial conditions and before reaching the set value of reduction in the impedance, equal to 0.8–0.9 of the initial value of impedance, the thickness of the tissue is estimated, and depending on the resulting thickness estimate, the heating rate of the treated tissue clamped between the electrodes is either maintained at the initially set level or increased. In order to estimate the thickness of the tissue, the set value of the energy Ez given to the load is selected herein, upon release whereof the value of the impedance Z corresponding to Ez is calculated. The set impedance reduction rate dZ/dt is stabilised, as well as, accordingly, the initially set tissue heating rate. The values of E and Ez are compared when the impedance changes the set number of times, and if the Ez is exceeded, the set value of the impedance reduction rate is changed proportionally to the ratio of the current energy E given to the load and the change in the impedance Z. In another variant of implementation, in order to estimate the total energy Ep and the maximum power Wmax required to achieve transmurality, additionally, after verifying the initial conditions and before reaching the set value of reduction in the impedance equal to 0.8–0.9 of the initial value of impedance, the thickness of the tissue is estimated, and depending on the resulting thickness estimate, the heating rate of the treated tissue clamped between the electrodes is either maintained at the initially set level or increased. In order to estimate the thickness of the tissue, the set value of the impedance Z is selected herein, and upon reaching said value, the energy Ez given to the load is calculated. The set impedance reduction rate dZ/dt is stabilised, as well as, accordingly, the set tissue heating rate. The set value of the impedance Z and the current value of the impedance Z are compared when the impedance changes the set number of times, and if the current Z exceeds the set value of the impedance Z, the set value of the impedance reduction rate is changed proportionally to the ratio of the current energy E given to the load and the change in the impedance Z.

EFFECT: provided method for controlling a surgical instrument with the passage of an electric current through the tissues subject to heating, for monitoring the transmurality of tissue damage in myocardial ablation during cardiac surgeries and for the sufficiency thereof.

20 cl, 6 dwg

Description

FIELD OF TECHNOLOGY

SUBSTANCE: invention relates to medicine, namely to methods for controlling a surgical instrument with the passage of an electric current through tissues to be heated, in particular, to control and sufficiency of transmurality of tissue damage during myocardial ablation during cardiac surgery.

PRIOR ART

A known method and device for transmural ablation [US2003125729 A1, publ. 07/03/2003], in which bipolar RF energy is applied between two electrodes, thus removing the tissue between them. The monitoring device measures a suitable parameter, such as impedance or temperature, and indicates when tissue between the electrodes has been completely removed. In accordance with one aspect of the invention, a feedback system is provided for determining the temperature of ablated tissue. To this end, the clips include a series of thermocouples that are supported in and protrude slightly through the insulating member to engage any tissue sandwiched between the clips. Wires are attached to thermocouples to transmit the received information to a remote location.

The disadvantages of the monitoring method known for transmural ablation of the above device include the fact that the temperature of the sensor itself (thermocouple) will be measured, which, with a rapid temperature change, will differ from the temperature of the tissue at the measurement site. In addition, it is impossible to measure the temperature in the entire volume of the tissue, since the sensors can only be installed at some points. Selective temperature control does not make it possible to reliably determine the achievement of transmurality, since for this it is necessary to ensure that the lowest temperature region of the tissue is heated above the required threshold.

A known method of controlling the device for ablation by selecting the level of applied power depending on the impedance of the treated tissue, disclosed in the International application [WO2006080982 A1, publ. 08/03/2006] and including:

a) placing two electrodes of the ablation device on the tissue surface;

b) measurement of tissue impedance between the electrodes;

c) energizing the electrodes based on the measured tissue impedance by:

i) applying substantially constant power to the electrodes if the measured tissue impedance is between the first threshold impedance and the second threshold impedance, the first threshold impedance being less than the second threshold impedance;

ii) applying variable power to the electrodes if the measured tissue impedance is greater than the second threshold impedance, the variable power being inversely related to the tissue impedance.

The main disadvantage of this method is that the power is determined only by the value of the impedance at a given time. To evaluate it, the thickness of the tissue sandwiched between the electrodes is not taken into account. But a narrow and thin area of tissue and a thick and wide one can have the same impedance, and the power for ablation is different in each case. The power may turn out to be excessive for specific conditions, this will lead to local overheating and drying of the tissue in the zone of contact with the electrode, an increase in impedance and a false conclusion about the resulting transmurality. Insufficient power will lead to an increase in the ablation time and, accordingly, to undesirable heating of the tissue located close to the ablation zone.

A known method of ablation of biological tissues and a device for its implementation [RU2691845 C1, publ. 06/18/2019], in which, for a more reliable control (assessment) of the achievement of the fact and moment of transmurality of biological tissues in the process of their ablation, the tissue temperature is judged based on the rate of impedance change, while maintaining a certain power level to ensure a given rate of impedance change. From the power level and the corresponding impedance change rate, the energy required to heat the tissue to a certain temperature is calculated.

The method includes the following steps:

– placement of two electrodes of the device (instrument) for ablation in contact with the tissue surface in such a way that the treated tissue is located between the electrodes;

- applying voltage to the instrument electrodes;

– calculation of the tissue impedance value Z and the rate of its change dZ/dt;

– calculation of the power W and the rate of its change dW/dt;

– calculation of the energy E transferred to the load ;

– maintaining the set value of the impedance reduction rate;

– assessment of the value of the total energy Ep necessary to achieve tissue transmurality when the impedance value reaches a value of 0.7-0.8 of the initial impedance value;

- estimation of the maximum allowable power Wmax when the impedance value reaches a value of 0.7-0.8 from the initial impedance value;

– implementation of the transition to the mode of maintaining a constant impedance level (reaching a plateau);

– assessment of the achievement of transmurality based on the establishment of a power value W exceeding Wmax, or on the basis of the amount of energy E transferred to the load, exceeding the value of the total energy Ep required to achieve transmurality of the tissue, or after a specified time has elapsed after the transition to the mode of maintaining a constant impedance level.

The disadvantages of controlling the ablation device by the above method include the fact that in order to estimate the value of the total energy Ep and the maximum allowable power Wmax necessary to achieve tissue transmurality, the thickness of the tissue sandwiched between the electrodes is not taken into account.

And also in all known methods of controlling the ablation process, there is no control and regulation of the heating rate of the tissue clamped between the electrodes, depending on its thickness.

DISCLOSURE OF THE INVENTION

The invention is based on the task of creating a method for controlling a surgical instrument (ablation device) that provides uniform heating of both the surface and deep layers of the treated tissue when an electric current is passed through it, by setting the optimal heating rate.

The technical result is the optimization of the time of operations - the creation of a transmural zone of myocardial damage in the shortest possible period.

The problem is solved by the fact that, like the well-known, the proposed method for controlling a surgical instrument for ablation of biological tissues includes:

– connection of the bipolar ablation device to a power source, and the bipolar ablation device has two electrodes;

– placement of two electrodes of the device (instrument) for ablation in contact with the tissue surface in such a way that the treated tissue is located between the electrodes;

– supply voltage to the electrodes of the instrument and constant monitoring (measurement) of the tissue impedance Z(U/I) and the rate of its change dZ/dt, power W and the rate of its change dW/dt and calculation of the energy E transferred to the load during the entire ablation process;

- checking the initial (starting) conditions and heating the treated tissue at a given speed until the value of the set impedance reduction value is reached, which is 0.7 - 0.8 from the initial impedance value;

– assessment of the value of the total energy Ep required to achieve transmurality of the tissue and the maximum allowable power Wmax required to achieve transmurality, the transition to the mode of maintaining a constant impedance level (reaching a plateau);

– assessment of the achievement of transmurality based on the establishment of a power value W exceeding Wmax, or on the basis of the amount of energy E transferred to the load, exceeding the value of the total energy Ep required to achieve transmurality of the tissue, or after a specified time has elapsed after the transition to the mode of maintaining a constant impedance level.

What is new is that in order to estimate the total energy Ep and the maximum power Wmax required to achieve transmurality, additionally after checking the initial conditions and before reaching the value of the set impedance reduction value, which is 0.8–0.9 of the initial impedance value, the thickness is estimated. tissue and, depending on the thickness estimate obtained, either leave the heating rate of the treated tissue, clamped between the electrodes, initially set, or increase it by changing the set value of the impedance reduction rate.

Moreover, in version 1 of the method, the following steps are carried out to assess the thickness of the tissue:

- selection of some given value of energy Ez, given to the load, after the allocation of which the calculation of the value of the impedance _Z corresponding to Ez is performed;

– stabilization of the initially set impedance reduction rate dZ/dt and, accordingly, the tissue heating rate;

– comparison of the value of the current energy E and Ez when the impedance changes by a given number of times, and, in case of exceeding Ez,

– change in the set value of the impedance reduction rate is proportional to the ratio of the current energy E transferred to the load and the change in the impedance Z.

In this case, to assess the thickness of the processed tissue, the power from 5 to 10 W is initially selected.

In addition, the specified value of the energy Ez released into the tissue at the initial stage is selected from the range from 20 to 100 J, preferably 70 J.

In addition, the impedance reduction rate setpoint is selected from the range of 2% to 10%, preferably 5%.

Given that the specified time after the transition to the mode of maintaining a constant impedance level is no more than 10 seconds.

In addition, maintaining the set value of the impedance reduction rate and maintaining a constant impedance level is carried out by changing the power.

In this case, the rate of power change is selected from the range from 1 to 5 W/s and preferably not more than 3 to 5 W/s.

It is advisable that the value of the total energy Ep be 2-5 times greater than the energy value when the impedance value reaches a value of 0.7 - 0.8 of the initial impedance value.

It is advisable that the maximum allowable power Wmax be 3 - 6 times, preferably 4 - 5 times the power value when the impedance value reaches a value of 0.7 - 0.8 of the initial impedance value.

In addition, to calculate the initial impedance value, a voltage of 5 to 25 V, preferably 10 to 20 V, is applied to the electrodes.

Moreover, in version 2 of the method, the following steps are carried out to assess the thickness of the tissue:

– selection of a certain predetermined value of the impedance Z, after reaching which the energy E delivered to the load is calculated;

– stabilization of the given impedance reduction rate dZ/dt and, accordingly, the given tissue heating rate;

– comparison of the given impedance value and the current one when the impedance changes by a given number of times, and if the current Z _. exceeds the specified impedance value,

– change in the set value of the impedance reduction rate is proportional to the ratio of the current energy E transferred to the load and the change in the impedance Z.

In this case, to assess the thickness of the processed tissue, the power from 5 to 10 W is initially selected.

In addition, the set value of the reduction of the impedance to compare the set value of Z _. and the current value of Z is selected from the range of 0.8 - 0.9 from the initial value of the impedance, preferably 0.85.

In addition, the impedance reduction rate setpoint is selected from the range of 2% to 10%, preferably 5%.

Given that the specified time after the transition to the mode of maintaining a constant impedance level is no more than 10 seconds.

In addition, maintaining the set value of the impedance reduction rate and maintaining a constant impedance level is carried out by changing the power.

In this case, the rate of power change is selected from the range from 1 to 5 W/s and preferably not more than 3 to 5 W/s.

It is advisable that the value of the total energy Ep be 2-5 times greater than the energy value when the impedance value reaches a value of 0.7 - 0.8 of the initial impedance value.

It is advisable that the maximum allowable power Wmax be 3 - 6 times, preferably 4 - 5 times the power value when the impedance value reaches a value of 0.7 - 0.8 of the initial impedance value.

In addition, to calculate the initial impedance value, a voltage of 5 to 25 V, preferably 10 to 20 V, is applied to the electrodes.

The proposed method is designed to control the biological tissue ablation device. Devices are used in medicine to heat biological tissues in order to destroy a certain area of tissue without violating the integrity of the organ, including the creation of electrically insulating lines in some areas of the myocardium, preventing the pathological propagation of electrical signals that cause atrial fibrillation. With increasing temperature, the impedance of biological tissue decreases. This is mainly due to the dehydration of ions and a decrease in the viscosity of the medium, i.e. decrease in resistance to the movement of ions. The decrease in biological tissue impedance can be used to indirectly assess tissue temperature rise. It is known from earlier studies that, in accordance with the characteristic tissue impedance curve, the tissue impedance (resistance) decreases as it is heated, then when the temperature reaches about 70-90 ° C, the drop stops, and with further heating, as the tissue dries, it begins to increase. In this case, if a given volume of tissue with a given heat capacity is heated, then in order to achieve a certain temperature of the tissue, and, consequently, a certain decrease in the tissue impedance, it is necessary to expend a certain amount of energy. .

Under comparable exposure conditions, in this case, the same ablation instrument, and the same electrode area, a different amount of energy expended to heat the tissue to a given temperature will indicate a different thickness of the tissue between the electrodes. Therefore, for a particular instrument with a particular size of electrodes, the ratio of the initial impedance (resistance) to the expended energy required for a given reduction in impedance will reflect the thickness of the area of tissue sandwiched between the electrodes. Clamped one and the same volume of tissue at different lengths (and, consequently, areas) of tissue contact with the electrodes will be characterized by different thicknesses and different impedances. For example, twice the length (and hence the area) of tissue contact with electrodes, with the same tissue volume, will be characterized by twice the thickness and four times the impedance.

The process of heating the treated tissue occurs unevenly. First of all, and at a higher rate, the surface layers of the tissue that are in direct contact with the electrodes are heated. As tissue layers move away from the electrodes (deeper layers), the current density decreases and the tissue heating rate decreases. The thicker the tissue, the more the heating rate of the surface (closer to the electrodes) and deep tissue layers differs. Due to the presence of a temperature gradient between the surface and deep layers of the tissue, the heating of the deep layers of the tissue occurs not only due to the current passing through them, but also due to heat transfer from the surface layers to the deep ones. The heat transfer process has a finite speed and requires more time, the thicker the tissue. From the above, it follows that the rate of heating of the fabric should differ depending on its thickness. The thicker the tissue to be treated, the slower the heating rate must be to ensure uniform heating of the surface and deep layers of the tissue to be treated.

BRIEF DESCRIPTION OF THE DRAWINGS.

Hereinafter, the present invention will be described by way of example with reference to the accompanying drawings, in which:

On FIG. 1 shows a block diagram of a device for implementing the proposed method.

On FIG. 2 is a plot of impedance versus time.

On FIG. 3 shows the algorithm of the device in the form of a block diagram for option 1 of the proposed method:

Fig. 3a - the beginning of the ablation process before the transition to the horizontal section of the impedance (plateau),

fig. 3b - continuation of the ablation process and its completion.

On FIG. 4 shows the algorithm of the device in the form of a block diagram for option 2 of the proposed method:

Fig. 4a - the beginning of the ablation process before the transition to the horizontal section of the impedance (plateau),

fig. 4b - continuation of the ablation process and its completion.

Example 1 - Option 1 of the proposed method for controlling a biological tissue ablation device. Estimation of tissue thickness from a given energy.

After the initialization of the microprocessor of the control system 3, the tool is initially supplied from the generator 2 with a high-frequency voltage from 5 to 25 V, preferably 10 volts, and the initial impedance Zini is determined in the first 3 seconds. processed tissue and check whether the calculated impedance value is within the allowed range. If the calculated impedance is in the range of 20 to 300 ohms, 40 to 200 ohms is better to keep the voltage applied.

From the moment the ablation began, at intervals dt equal to 100 ms, in accordance with the first section of the graph shown in Fig. 2 (point t ₀ ), the microprocessor starts calculating the value of the tissue impedance Z and the rate of its change, the power W and the rate of its change, as well as the calculation of the energy E transferred to the load.

The microprocessor sets the power from 5 to 10W and calculates the amount of output energy according to the formula: E=E+W/10, calculates the current impedance and stabilizes the set impedance reduction rate (depends on the coefficient k1– sets the impedance reduction rate).

It has been experimentally established that at the beginning of ablation, to maintain a rate of impedance change of 5% per second, a small rate of power change is sufficient, for example, an increase in power by 1 W/s. As the tissue heats up, a larger power increment, such as 3W/s, is required to maintain a rate of impedance decrease of 5% per second.

The impedance reduction rate setpoint is selected from the range of 2% to 10%, preferably 5%.

For the stated range of impedance reduction rates from 2 to 10% per second, k1= from 0.002 to 0.01 at dt = 0.1 seconds (section in Fig. 2 up to point t1).

When the amount of energy released in the tissue reaches a predetermined value of energy, preferably equal to 100 J, the microprocessor evaluates the thickness of the tissue and calculates the coefficient k1 according to the formula:

,

,

where k6 is the coefficient of proportionality between k1 and the thickness of the fabric in conventional units. k6 = 0.001 to 0.01.

The coefficient k1 sets the impedance reduction rate and is inversely proportional to the tissue thickness. The heating rate of the fabric (low speed is set by default) when recalculating it can be increased if the fabric being processed is thin. As the temperature rises, tissue resistance decreases. This makes it possible to judge the heating of the tissue by its impedance.

To calculate the impedance change rate by the microprocessor depending on Zini (dZ/dt*k1) and the set value of the impedance reduction rate equal to 5%, k1=0.005 is set.

For the declared impedance reduction rate range from 2 to 10% per second, k1 = from 0.002 to 0.01 with dt = 0.1 seconds, the calculated value of k1 to determine the heating rate (point t1 in Fig. 2), depending on Z init, for example , may be:

– for Zini=100 Ohm and reduction to Z=0.85* Zini (up to 85 Ohm) and for k6=0.0036, the calculated value k1=0.005;

– for Zini=200 Ohm and reduction to Z=0.85* Zini (up to 170 Ohm) and for k6=0.0036, calculated value k1=0.002;

for Zini=50 Ohm and reduction to Z=0.85* Zini (up to 42 Ohm) and for k6=0.0036, the calculated value k1=0.01.

After assessing the thickness of the tissue and changing the rate of its heating, the microprocessor proceeds to the assessment of the total energy En necessary to achieve transmurality and the maximum allowable power Wmax.

Set the value k5=0.3 to control the current rate of change of power depending on the set value of the rate of change of power equal to 3W/s. Possible range of values k5 = from 0.1 to 0.5.

The energy E is equal to 1/10 of the sum of the instantaneous power values W at time intervals dt=0.1 second.

Also, the microprocessor, from the moment the ablation begins, calculates the rate of change of the power supplied to the instrument dW / dt and adjusts the power to maintain the specified rate of impedance reduction, calculating the power according to the formula:

W=W±(Zstart*k1-dZ)*k2, where k1=0.005 for a given speed of 5% per second, dZ is the change in impedance over time dt, k2 from 0.2 to 1 is the power change step.

If the dZ/dt decline rate is greater than 5% per second, the microprocessor reduces power in proportion to the speed deviation until the impedance decline rate is restored to 5% per second. If the impedance decline rate dZ/dt is below 5% per second, the microprocessor increases power in proportion to the speed deviation until the impedance decline rate is restored to 5% per second and then controls the power, maintaining the impedance decline rate unchanged at 5% per second.

When the value of the impedance Z is less than that calculated by the formula Z=0.75*Zini. the microprocessor calculates the value of the total energy Ep required to achieve transmurality of the tissue lesion according to the formula: Ep =E*k3, where k3 from 2 to 5 – total energy coefficient.

At the same time, the microprocessor calculates the maximum allowable power Wmax according to the formula: Wmax = W*k4, where k4 is the power factor equal to 4. The possible range of power factor values is from 3 to 6.

It has been experimentally established that during ablation the impedance Z decreases to 50% or more of the initial impedance Zini. Point t2 on the graph of Fig. 2 is chosen at the level of 75% of Zinit, approximately in the middle of the maximum range of impedance change.

At point t2, the released energy E is between 20% and 50% of the total energy needed to achieve transmurality. Therefore, the possible range of k3 values is from 2 to 5.

At point t2, the power W is between 15% and 30% of the maximum allowable power W max for a given volume of tissue. Therefore, k4 is chosen in the range from 3 to 6.

When the impedance Z approaches the minimum value (plateau - section 3 in Fig. 2), the power increase rate can exceed 3 W/s. Therefore, k5 is chosen in the range from 0.1 to 0.5.

When the value of the rate of change of power dW/dt is greater than the set value of 3W/s go into the mode of maintaining a constant level of impedance (reaching a plateau), by adjusting the power, increasing or decreasing it depending on the fluctuations in the impedance Z, in order to prevent excessive heating of the tissue.

Different current density in the tissue leads to uneven energy release and different temperatures of tissue areas. To compensate for the temperature difference, it is necessary to maintain the tissue at the maximum temperature reached for some time. By maintaining the impedance at a constant level by adjusting the power, the machine keeps the average temperature of the tissue unchanged. In this case, the temperature is redistributed and equalized between adjacent sections of the tissue due to heat transfer.

The preferred predetermined time after the implementation of the transition to the mode of maintaining a constant impedance level is not more than 10 seconds.

The microprocessor displays a message about the achievement of a transmural tissue lesion and stops the generator:

1. When the total energy Ep is released into the load;

2. With an increase in power above W max;

3. After the specified time, generated by the timer 2 (the algorithm in Fig.3), after the transition to the mode of maintaining a constant impedance level.

To protect against excessive heating and tissue damage, the generator is turned off after 40 seconds formed by timer 1 (the algorithm in Fig. 3) from the start of ablation, regardless of other criteria.

Example 2 - Option 2 of the proposed method for controlling the biological tissue ablation device. Estimating tissue thickness from a given impedance change (dZ).

After the initialization of the microprocessor of the control system 3, the instrument is initially supplied from the generator 2 with a high-frequency voltage from 5 to 25 V, preferably 10 volts, and in the first 3 seconds the initial impedance Zini of the treated tissue is determined and check the compliance of the calculated impedance value with the allowed range. If the calculated impedance is in the range of 20 to 300 ohms, 40 to 200 ohms is better to keep the voltage applied.

From the moment the ablation began, at intervals dt equal to 100 ms, in accordance with the first section of the graph shown in Fig. 2 (point t0), the microprocessor starts calculating the value of the tissue impedance Z and the rate of its change, the power W and the rate of its change, as well as the calculation of the energy E transferred to the load.

The microprocessor sets the power from 5 to 10W, calculates the amount of output energy according to the formula: E=E+W/10, controls the impedance change and stabilizes the set impedance reduction rate (depends on k1– sets the impedance reduction rate).

It has been experimentally established that at the beginning of ablation, to maintain a rate of impedance change of 5% per second, a small rate of power change is sufficient, for example, an increase in power by 1 W/s. As the tissue heats up, a larger power increment, such as 3W/s, is required to maintain a rate of impedance decrease of 5% per second.

The impedance reduction rate setpoint is selected from the range of 2% to 10%, preferably 5%.

For the stated range of impedance reduction rates from 2 to 10% per second, k1= from 0.002 to 0.01, with dt = 0.1 seconds (section in Fig. 2 to point t1).

When the impedance changes by a factor of k7, the microprocessor evaluates the tissue thickness and calculates the coefficient k1 using the formula:

,

,

where k6 is the coefficient of proportionality between k1 and the thickness of the fabric in arbitrary units, taken k6 = from 0.001 to 0.01.

And the coefficient k7 is the impedance change threshold for assessing the tissue thickness, chosen in the range from 0.8 to 0.9, preferably 0.85 from the initial impedance value (point t1 on the impedance curve - Fig.2).

Next, the transition to the algorithm similar to example 1: changing the heating rate, assessing the total energy En, the required and maximum allowable power Wmax and the algorithm for achieving transmurality of the treated tissue.

Claims (44)

1. A method for controlling a surgical instrument for ablation of biological tissues, characterized in that it includes: – connection of the bipolar ablation device to a power source, and the bipolar ablation device has two electrodes; – placing the two electrodes of the ablation instrument in contact with the tissue surface so that the treated tissue is located between the electrodes; – application of voltage to the electrodes of the instrument, and constant measurement of the tissue impedance Z and the rate of its change dZ/dt, power W and the rate of its change dW/dt, and calculation of the energy E transferred to the load during the entire ablation process; – checking the initial conditions and heating the treated tissue at a given rate until the value of the set impedance reduction value is reached, which is 0.7–0.8 from the initial impedance value; – assessment of the value of the total energy Ep required to achieve tissue transmurality and the maximum allowable power Wmax required to achieve transmurality, transition to the mode of maintaining a constant impedance level; – assessment of the achievement of transmurality based on the establishment of a power value W exceeding Wmax, or on the basis of the amount of energy E transferred to the load, exceeding the value of the total energy Ep required to achieve transmurality of the tissue, or after a specified time has elapsed after the transition to the mode of maintaining a constant impedance level, characterized in that To estimate the total energy Ep and the maximum power Wmax required to achieve transmurality, additionally, after checking the initial conditions and before reaching the value of the set value of impedance reduction, which is 0.8–0.9 of the initial impedance value, the tissue thickness is estimated and, depending on of the obtained assessment of the thickness, either leave the heating rate of the processed tissue, clamped between the electrodes, initially set, or increase it, while to assess the thickness of the tissue, the following is carried out: - selection of a given value of energy Ez, given to the load, after which the calculation of the value of the impedance _Z corresponding to Ez is performed; – stabilization of the given rate of impedance decrease dZ/dt and, accordingly, the initially set tissue heating rate; – comparison of the values of E and Ez when the impedance changes by a given number of times, and in case of exceeding Ez, – change in the set value of the impedance reduction rate is proportional to the ratio of the current energy E transferred to the load and the change in the impedance Z. 2. The method according to p. 1, characterized in that to assess the thickness of the treated tissue, initially choose a power of 5 to 10 watts. 3. The method according to claim 1, characterized in that the set value of the energy Ez given in the tissue at the initial stage is selected from the range from 20 to 100 J, preferably 70 J. 4. The method according to claim. 1, characterized in that the specified value of the impedance reduction rate is selected from the range from 2-10% per second and is preferably 5% per second. 5. The method according to claim 1, characterized in that the specified time after the transition to the mode of maintaining a constant impedance level is no more than 10 seconds. 6. The method according to p. 1, characterized in that maintaining the set value of the impedance reduction rate is carried out by changing the power . 7. The method according to p. 1, characterized in that the maintenance of a constant impedance level is carried out by changing the power. 8. The method according to p. 1, characterized in that the rate of power change is selected from the range from 1 to 5 W/s and is preferably not more than 3-5 W/s. 9. The method according to claim 1, characterized in that the value of the total energy Ep exceeds the energy value by 2-5 times when the impedance value reaches a value of 0.7-0.8 of the initial impedance value. 10. The method according to claim 1, characterized in that the maximum allowable power Wmax exceeds 3-6 times, preferably 4-5 times, the power value when the impedance value reaches a value of 0.7-0.8 of the initial impedance value. 11. A method for controlling a surgical instrument for ablation of biological tissues, characterized in that it includes: – connection of the bipolar ablation device to a power source, and the bipolar ablation device has two electrodes; - placing the two electrodes of the ablation instrument in contact with the tissue surface so that the treated tissue is located between the electrodes; – application of voltage to the electrodes of the instrument, and constant measurement of the tissue impedance Z and the rate of its change dZ/dt, power W and the rate of its change dW/dt, and calculation of the energy E transferred to the load during the entire ablation process; – checking the initial conditions and heating the treated tissue at a given rate until the value of the set impedance reduction value is reached , which is 0.7–0.8 from the initial impedance value; – assessment of the value of the total energy Ep required to achieve tissue transmurality and the maximum allowable power Wmax required to achieve transmurality, transition to the mode of maintaining a constant impedance level; – assessment of the achievement of transmurality based on the establishment of a power value W exceeding Wmax, or on the basis of the amount of energy E transferred to the load, exceeding the value of the total energy Ep required to achieve transmurality of the tissue, or after a specified time has elapsed after the transition to the mode of maintaining a constant impedance level, characterized in that To estimate the total energy Ep and the maximum power Wmax required to achieve transmurality, additionally, after checking the initial conditions and before reaching the value of the set value of impedance reduction, which is 0.8–0.9 of the initial impedance value, the tissue thickness is estimated and, depending on of the obtained assessment of the thickness, either the heating rate of the processed tissue, clamped between the electrodes, is initially set, or it is increased, while to evaluate the thickness, the following is carried out: – selection of a predetermined value of the impedance Z, after reaching which the energy E transferred to the load is calculated; – stabilization of the given impedance reduction rate dZ/dt and, accordingly, the given tissue heating rate; – comparison of the given value of the impedance Z and the current value of the impedance Z when it changes by a given number of times, and if the current Z _. exceeds the specified value of the impedance Z, – change in the set value of the impedance reduction rate is proportional to the ratio of the current energy E transferred to the load and the change in the impedance Z. 12. The method according to p. 11, characterized in that to assess the thickness of the tissue to be treated, initially choose a power of 5 to 10 watts. 13. The method according to p. 11, characterized in that the set value of the reduction of the impedance to compare the set value Z _. and the current value of Z is selected from the range of 0.8–0.9 from the initial value of the impedance. 14. The method according to claim 11, characterized in that the impedance reduction rate setpoint is selected from the range of 2-10% per second and is preferably 5% per second. 15. The method according to claim 11, characterized in that the specified time after the transition to the mode of maintaining a constant impedance level is no more than 10 seconds. 16. The method according to claim 11, characterized in that maintaining the set value of the impedance reduction rate is carried out by changing the power . 17. The method according to claim 11, characterized in that maintaining a constant impedance level is carried out by changing the power. 18. The method according to p. 11, characterized in that the rate of power change is selected from the range from 1 to 5 W/s and is preferably not more than 3-5 W/s. 19. The method according to claim 11, characterized in that the value of the total energy Ep exceeds the energy value by 2-5 times when the impedance value reaches a value of 0.7–0.8 of the initial impedance value. 20. The method according to claim 11, characterized in that the maximum allowable power Wmax exceeds 3-6 times, preferably 4-5 times, the power value when the impedance value reaches a value of 0.7–0.8 of the initial impedance value.

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