A method and device for preventing arc generation during pulse electric field ablation

Abstract

The present invention relates to the field of medical device technology, and more specifically, to a method for preventing arc generation during pulse electric field ablation. The method for preventing arc generation during pulse electric field ablation is characterized in that: the specific method flow is as follows: placing an ablation catheter at a specified position; determining the peak value U of the output voltage of a pulse generator; peak ; Measure the output current I0; Calculate the catheter's contact impedance Z Contact ; When calculating that no arc is generated, the close impedance Z0=Z Contact ; Calculate the safety redundant impedance threshold Z th =εZ0; Calculate the safety redundant impedance threshold Z th The corresponding safety redundancy current #imgabs0# is ablated, and the measurement result is I Meas During ablation, Meas and I th The relative size of the value is judged. Meas <I th When the pulse controller controls the pulse generator to stop the pulse emission, it means that an arc is about to be generated. At this time, the pulse controller controls the pulse generator to stop the pulse emission, thereby preventing the arc from being generated. Compared with the prior art, the present invention solves the problem of arc generation from the root, greatly increasing the safety of pulsed field ablation (PFA).

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, in particular to a method for preventing arc generation during pulse electric field ablation. Background Art

[0002] In the clinical application of modern medicine, pulsed field ablation (PFA) can be used to treat diseases such as tumors and arrhythmias caused by uncontrolled cell proliferation or ectopic pacemakers in the heart. The main principle is that when the aforementioned tumor tissue cells or myocardial cells are subjected to an external strong electric field (electric field strength of about 100 to 10,000V / cm), their cell membranes undergo irreversible electroporation, leading to cell apoptosis and necrosis, which are then cleared by the immune system, thereby achieving the purpose of treatment.

[0003] The above-mentioned pulsed electric field ablation method is similar to traditional radiofrequency ablation (RFA) in that both require the use of a dedicated medical electrode catheter, and a specially trained physician inserts the catheter into the patient's body so that the catheter tip reaches the lesion to be ablated, and releases energy to the lesion through the electrode on the catheter. Compared with radiofrequency ablation (RFA), the advantage of pulsed electric field ablation (PFA) is that it is not based on thermal effects and thermal damage to tissues to achieve therapeutic effects, so it is not easy to cause damage to normal tissues around the ablation target during radiofrequency ablation (RFA), and it can also reduce the occurrence of complications such as esophageal and phrenic nerve damage.

[0004] In the specific use of pulsed field ablation (PFA), it is necessary to keep the catheter used for ablation in good contact with the ablated tissue so that the energy can be fully released to the ablated tissue. Usually, the method of measuring the contact impedance is used to determine whether it is in good contact. However, during the ablation process, due to the water and ions contained in the blood, as well as the gas dissolved therein, when subjected to an external strong electric field, an electrochemical reaction occurs at the interface between the catheter electrode and the blood, and tiny bubbles are generated on the electrode surface, which makes the contact between the electrode and the ablated tissue worse; on the other hand, when too many tiny bubbles are generated on the electrode surface, they are easily broken down by the strong electric field between the discharge electrodes to form an arc. Once an arc is generated near the ablated tissue, it indicates that the surrounding area of ​​the ablated tissue has been thermally damaged, which can easily cause thermal necrosis of these tissues and cause complications.

[0005] Among the currently disclosed technologies, the invention patent application CN202010662682.8 discloses a cardiac pulse electric field ablation catheter, which controls the spacing between electrodes, the cross-sectional area of ​​the electrodes, and the width of the electrodes used for the ablation catheter, in order to reduce the generation of arcs during high-voltage pulse ablation and avoid safety accidents. Although the above invention changes the design of the electrodes, it does not involve the core of the pulse electric field ablation arc, that is, controlling and / or identifying the generation of tiny bubbles on the surface of the electrode to fundamentally prevent the generation of arcs.

[0006] Therefore, the present invention lacks a method and device for preventing arcing between catheter electrodes during pulsed field ablation (PFA), which can fundamentally solve the problem of arcing and greatly increase the safety of pulsed field ablation (PFA). Summary of the invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides a method for preventing arc generation during pulsed field ablation, thereby solving the problem of arc generation from the root and greatly increasing the safety of pulsed field ablation (PFA).

[0008] In order to achieve the above purpose, a method for preventing arc generation during pulse electric field ablation is designed, which is characterized by: the specific method flow is as follows:

[0009] (1) placing the ablation catheter at the designated location and turning on a device to prevent arcing during pulsed electric field ablation;

[0010] (2) Determine the peak value U of the pulse generator output voltage according to the characteristics of the tissue to be ablated. Peak ;

[0011] (3) Measure the output current I0 of the pulse generator;

[0012] (4) According to step (3), calculate the contact impedance Z between the catheter electrode and the tissue Contact ;

[0013] (5) Calculate the impedance between the catheter electrode and the tissue when no arc is generated. Z0 = Z Contact ;

[0014] (6) Calculate the safety redundant contact impedance threshold Z th =εZ0, where the safety redundancy factor ε∈(1,5];

[0015] (7) Calculate the safety redundant contact impedance threshold Z th The corresponding safety redundancy current

[0016] (8) ablation is performed, and the pulse current is measured in real time by a pulse current detector. The measurement result is IMeas ;

[0017] (9) During ablation, Meas and I th The relative size of the value is judged. Meas <I th When the pulse controller stops the pulse generator from releasing the pulse, it means that an arc is about to be generated.

[0018] The device for preventing arc generation during pulse electric field ablation includes a pulse generator, a pulse controller, a pulse output switching array, a pulse voltage detector, and a pulse current detector. The output end of the pulse controller is respectively connected to the pulse generator and the pulse output switching array. The pulse generator and the pulse output switching array are connected through a line, and the line between the pulse generator and the pulse output switching array is respectively connected to a pulse voltage detector and a pulse current detector. The signal output ends of the pulse voltage detector and the pulse current detector are connected to the signal input end of the pulse controller.

[0019] The output end of the pulse controller is connected to a high-voltage power supply module, and the high-voltage power supply module is connected to a pulse generator through a line.

[0020] The pulse output switching array is connected to the ablation catheter via a line.

[0021] The pulse output switching array includes a plurality of relays, one end of the relay is connected to the pulse generator, and the other end of the relay is connected to the ablation catheter through a connecting cable.

[0022] Compared with the prior art, the present invention provides a method for preventing arc generation during pulsed field ablation, solves the problem of arc generation from the root, and greatly increases the safety of pulsed field ablation (PFA). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a system structure diagram of the present invention.

[0024] Figure 2 This is the schematic diagram of the high voltage power supply module.

[0025] Figure 3 This is the schematic diagram of the pulse generator implementation.

[0026] Figure 4 Schematic diagram of the output switching array.

[0027] Figure 5 This is the control schematic diagram of the pulse controller.

[0028] Figure 6It is a waveform diagram obtained by the current detection unit before and after the arc is generated in the pulse electric field ablation device in the embodiment of the present invention.

[0029] Figure 7 Schematic diagram of the change in impedance between the catheter electrode and the tissue before and after the arc is generated during the pulsed electric field ablation process in an embodiment of the present invention.

[0030] See also Figure 1 ,1 is a high voltage power supply module, 2 is a pulse generator, 3 is a pulse output switching array, 4 is a pulse controller, 5 is a pulse voltage detector, 6 is a pulse current detector, and 7 is an ablation catheter. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] like Figure 1 As shown, the device for preventing arc generation during pulse electric field ablation includes a pulse generator, a pulse controller, a pulse output switching array, a pulse voltage detector, and a pulse current detector. The output end of the pulse controller 4 is respectively connected to the pulse generator 2 and the pulse output switching array 3, the pulse generator 2 is connected to the pulse output switching array 3 through a line, and the line between the pulse generator 2 and the pulse output switching array 3 is respectively connected to a pulse voltage detector 5 and a pulse current detector 6, and the signal output ends of the pulse voltage detector 5 and the pulse current detector 6 are connected to the signal input end of the pulse controller 4.

[0033] The output end of the pulse controller 4 is connected to the high-voltage power module 1 , and the high-voltage power module 1 is connected to the pulse generator 2 through a line.

[0034] The pulse output switching array 3 is connected to the ablation catheter 7 via a line.

[0035] The pulse output switching array 3 includes a plurality of relays, one end of which is connected to the pulse generator 2 , and the other end of which is connected to the ablation catheter 7 via a connecting cable.

[0036] like Figure 2 As shown, the high-voltage power supply module 1 includes an AC-DC power supply module, a DC-DC conversion circuit module, and 220 AC voltage. One end of the AC-DC power supply module is connected to the 220 AC voltage, and the other end of the AC-DC power supply module is connected to the DC-DC conversion circuit module. The DC-DC conversion circuit module is connected to the boost controller inside the pulse controller 4.

[0037] The high-voltage power supply module 1 provides a high-voltage DC voltage for the pulse generator 2. The 220V AC network power supply outputs a 24V low-voltage DC power supply through a universal AC-DC power supply. The 24V DC power is then boosted to a 100-3000V high-voltage DC power supply through an adjustable voltage DC-DC conversion circuit and output to the pulse generator 2.

[0038] The pulse generator 2 is used to output unipolar or bipolar electrical pulses. The aforementioned unipolar electrical pulses refer to electrical pulses that do not cross zero and have only a positive half cycle; bipolar electrical pulses refer to electrical pulses that cross zero and have a positive half cycle and a negative half cycle, and the pulse amplitudes of the positive and negative half cycles may be equal or unequal. Figure 3 As shown, the output electric energy of the high-voltage power supply is stored by capacitor C1. When IGBT switch Q1 and IGBT switch Q4 are turned on at the same time, Pulse+ generates a positive voltage relative to Pulse-; and when IGBT switch Q2 and IGBT switch Q3 are turned on at the same time, Pulse+ generates a negative voltage relative to Pulse-. The pulse voltage amplitude is approximately equal to the energy storage voltage in the capacitor. At the same time, the output voltages of Pulse+ and Pulse- are directly divided and attenuated to provide the measurement circuit with an output voltage acquisition signal. In addition, the voltage on the shunt resistor R1 can be measured to obtain the output current of the pulse generator 2. The amplitude of the above-mentioned electric pulse is 100-3000V, the pulse width is 10ns-1000μs, the pulse interval is 10ns-1s, and the number of repetitions is 1-2000.

[0039] like Figure 4 As shown, the pulse output switching array 3 includes a plurality of relays, one end of the relay is connected to the pulse generator 2, and the other end of the relay is connected to the ablation catheter 7 via a connecting cable.

[0040] The pulse output switching array 3 is a series of relays, and its interface is connected to the external ablation catheter 7 of the present invention through a catheter connection cable. Figure 4 As shown, the pulse generator 2 outputs Pulse+ and Pulse- which are connected to the multi-channel output electrodes in a switch matrix manner to achieve any configuration of the ablation catheter electrode output pulses.

[0041] like Figure 5 As shown, the pulse controller 4 is used to coordinate the work of the above modules. The main controller in the pulse controller 4 controls the on and off of the high-voltage power supply according to the ablation voltage, controls the IGBT driver to generate the required ablation pulse according to the preset pulse waveform, monitors the pulse voltage and pulse current, and determines whether to terminate the discharge in advance according to the relationship between the voltage and current. In addition, the discharge electrode of the ablation catheter 7 is configured by controlling the relay in the pulse output switching array 3, making the ablation operation more flexible.

[0042] A method for preventing arc generation during pulse electric field ablation, the specific method process is as follows:

[0043] (1) placing the ablation catheter at the designated location and turning on a device to prevent arcing during pulsed electric field ablation;

[0044] (2) Determine the peak value U of the pulse generator output voltage according to the characteristics of the tissue to be ablated. Peak ;

[0045] (3) Measure the output current I0 of the pulse generator;

[0046] (4) According to step (3), calculate the contact impedance Z between the catheter electrode and the tissue Contact ;

[0047] (5) Calculate the impedance between the catheter electrode and the tissue when no arc is generated. Z0 = Z Contact ;

[0048] (6) Calculate the safety redundant contact impedance threshold Z th =εZ0, where the safety redundancy factor ε∈(1,5];

[0049] (7) Calculate the safety redundant contact impedance threshold Z th The corresponding safety redundancy current

[0050] (8) ablation is performed, and the pulse current is measured in real time by a pulse current detector. The measurement result is I Meas ;

[0051] (9) During ablation, Meas and I th The relative size of the value is judged. Meas <I th When the pulse controller stops the pulse generator from releasing the pulse, it means that an arc is about to be generated.

[0052] Embodiment 1:

[0053] like Figure 6 , Figure 7 FIG. 1 is a waveform diagram of a pulsed electric field ablation device in an embodiment of the present invention, obtained by a current detection unit before and after an arc is generated. Q is the current before the arc is generated; I Arc is the current when the arc is generated. In actual use, for a certain tissue, the peak value of the output voltage of the pulse generator is U Peak It can be measured by a pulse voltage detector and is a constant value. ContactWhen there is no significant change, the discharge current should follow Ohm's law, that is:

[0054] Before the arc is generated, the contact impedance Z between the catheter electrode and the tissue can be calculated by formula 1 Contact :

[0055] As can be seen in the figure, I Arc >>I0, that is, the current when the arc is generated is much greater than the current when the arc is not generated. If you try to use formula 1 to calculate the impedance Z when the arc is generated Arc , then:

[0056] However, in the actual ablation process, the impedance change of the human body's internal tissue is unlikely to occur suddenly, and the contact impedance Z between the catheter and the human body's internal tissue is Contact It is also impossible for a sudden change to occur in a short period of time to the extent of causing an arc. Figure 6 The current changes from I0 to I Arc In the process, it can be found that the current amplitude first decreases slowly, and then suddenly increases sharply when the arc is generated, that is, close to the impedance Z Contact There is a slow growth process before the mutation. By consulting the literature, it is found that Israel Byrd et al. pointed out in US 2019 / 0307500 that in addition to the shape of the catheter and the electrode, the spacing between the electrodes, and the cross-sectional area of ​​the electrodes, the microbubbles generated between the electrodes during the ablation process are another key factor leading to the arc generation. Contact The phenomenon of a slow increase before the sudden change can be analyzed to show that in the actual ablation process, microbubbles will gradually accumulate between the discharge electrodes of the catheter. The aforementioned microbubbles have the property of insulation. When a large number of them cover the surface of the electrode, the effective output area of ​​the electrode becomes smaller, resulting in the electrode-myocardial contact impedance Z Contact rise.

Claims

1. A device for preventing arcing during pulse electric field ablation, characterized in that: The device for preventing arc generation during pulse electric field ablation comprises a pulse generator, a pulse controller, a pulse output switching array, a pulse voltage detector, and a pulse current detector. The output end of the pulse controller (4) is respectively connected to the pulse generator (2) and the pulse output switching array (3). The pulse generator (2) and the pulse output switching array (3) are connected via a line. The line between the pulse generator (2) and the pulse output switching array (3) is respectively connected to a pulse voltage detector (5) and a pulse current detector (6). The signal output ends of the pulse voltage detector (5) and the pulse current detector (6) are connected to the signal input end of the pulse controller (4). The method for preventing arc generation during pulse electric field ablation is as follows: Step 1, placing the ablation catheter at a designated position, and turning on a device to prevent arcing during pulse electric field ablation; Step 2: Determine the peak value U of the output voltage of the pulse generator according to the characteristics of the tissue to be ablated. Peak ; Step 3, measuring the output current I0 of the pulse generator; Step 4: Calculate the impedance Z between the catheter electrode and the tissue according to step 3. Contact ; Step 5: Calculate the impedance Z0=Z between the catheter electrode and the tissue when no arc is generated. Contact ; Step 6: Calculate the safety redundancy impedance threshold Z th =εZ0, where the safety redundancy factor ε∈(1,5]; Step 7: Calculate the safety redundancy impedance threshold Z th The corresponding safety redundancy current Step 8, ablation is performed, and the pulse current is measured in real time by a pulse current detector, and the measurement result is I Meas ; Step 9: During ablation, Meas and I th The relative size of the value is judged. Meas <I th When the pulse controller stops the pulse generator from releasing the pulse, it means that an arc is about to be generated.

2. The device for preventing arc generation during pulse electric field ablation according to claim 1, characterized in that: The output end of the pulse controller (4) is connected to a high-voltage power supply module (1), and the high-voltage power supply module (1) is connected to a pulse generator (2) via a line.

3. The device for preventing arc generation during pulse electric field ablation according to claim 1, characterized in that: The pulse output switching array (3) is connected to the ablation catheter (7) via a line.

4. A device for preventing arc generation during pulse electric field ablation according to claim 1 or 3, characterized in that: The pulse output switching array (3) comprises a plurality of relays, one end of which is connected to the pulse generator (2), and the other end of which is connected to the ablation catheter (7) via a connecting cable.

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