METHOD FOR CONTROLLING AN ABLATION APPARATUS FOR BIOLOGICAL TISSUES (2 VARIANTS) Russian patent published in 2022 - IPC A61B18/12 A61B5/53 A61B5/01 A61B18/14 

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