Atrial fibrillation ablation cryoballoon atraumatic positioning device

Abstract

The application discloses a noninvasive positioning device for atrial fibrillation ablation cryoballoon, and relates to the field of balloon noninvasive positioning technology, and solves the problems of low resolution, low precision and harm to human body caused by long-time use of X-rays in the prior art positioning mode. The noninvasive positioning device for atrial fibrillation ablation cryoballoon comprises a main controller, an impedance test circuit, a three-dimensional reconstruction system, a channel selection circuit and an electrode array; the hardware system has high compatibility and low cost, and harmful rays do not need to be used for a long time during the operation process, so that the safety is high. The electrode array is used for balloon positioning, and the difficulty of implementation is low, and the user does not need to be trained again. The impedance signal is used for balloon positioning, and the expansibility is good, and other technologies can be used in a stacked mode.

Description

Technical Field

[0001] The present invention relates to the technical field of non-invasive balloon positioning technology, and in particular to a non-invasive positioning device for atrial fibrillation ablation cryoballoon. Background Art

[0002] Atrial fibrillation (AF) is a serious health hazard. The risks of AF include increased risk of stroke and congestive heart failure, severely impacting patients' quality of life. Ablation therapy is currently one of the most effective treatments. Ablative energy sources include radiofrequency, cryoablation, and laser. RF catheter ablation is the most commonly used method for treating AF. Balloon cryoablation is a new technology for treating paroxysmal AF. It works by evaporating a liquid refrigerant, removing heat from the tissue, lowering the temperature of the target ablation site and destroying abnormal electrophysiological tissue, thereby achieving the desired effect. RF ablation for treating arrhythmias has become a growing industry trend. Therefore, during RF ablation procedures, real-time positioning of the balloon assembly is crucial to the success of the procedure.

[0003] Traditional positioning in this field is typically based on X-ray fluoroscopy using single or dual-wing systems. Furthermore, medical imaging techniques such as ultrasound (US), computed tomography (CT), or MRI can be used to obtain geometric information about the patient before interventional procedures. During the interventional procedure, mapping and navigation data must be registered with offline geometric information in some way. However, these methods suffer from low resolution, limited accuracy, and the harmful effects of prolonged X-ray use on the human body.

[0004] Therefore, using other mapping and positioning methods to position the balloon component has certain limitations in terms of clinical operation difficulty. Long-term radiation measurement also restricts the long-term use of these technologies. Therefore, there is an urgent need for a low-cost, low-invasive balloon positioning technology to provide auxiliary means for clinical surgery. Summary of the Invention

[0005] The present invention provides a non-invasive positioning device for atrial fibrillation ablation cryoballoon, which solves the problems of low resolution, low precision and harmfulness of long-term use of X-rays to the human body in existing positioning methods.

[0006] The present invention provides a non-invasive positioning device for an atrial fibrillation ablation cryoballoon, comprising: a main controller, an impedance testing circuit, a three-dimensional reconstruction system, a channel selection circuit, and an electrode array; the main controller is connected to the impedance testing circuit, the impedance testing circuit is connected to the channel selection circuit, the channel selection circuit is connected to the electrode array, the three-dimensional reconstruction system is connected to the main controller, and the electrode array is arranged on the surface of a human body; the impedance testing circuit is used to select a channel using the channel selection circuit to measure the impedance information of the electrode array; the main controller is used to send the impedance information to the three-dimensional reconstruction system; the three-dimensional reconstruction system is used to receive the impedance information, reconstruct a boundary model based on prior information of a CT image, solve the distribution of conductivity changes in the electrode array according to the impedance information, and realize balloon positioning according to the distribution of conductivity changes.

[0007] Furthermore, the impedance testing circuit includes an excitation channel and an acquisition channel, and the excitation channel and the acquisition channel are connected to the electrode array through a channel selection circuit; the excitation channel includes a DDS waveform generator and a voltage-controlled constant current source circuit, the main controller is connected to the DDS waveform generator, and the DDS waveform generator is connected to the voltage-controlled constant current source circuit; the acquisition channel includes a differential amplifier circuit, a bandpass filter circuit, an amplitude adjustment circuit and an A / D acquisition circuit, the differential amplifier circuit is connected to the bandpass filter circuit, the bandpass filter circuit is connected to the amplitude adjustment circuit, the amplitude adjustment circuit is connected to the A / D acquisition circuit, and the A / D acquisition circuit is connected to the main controller.

[0008] Furthermore, the DDS waveform generator is used to generate a voltage signal, and the voltage-controlled constant current source circuit is used to convert the voltage signal into a current signal.

[0009] Furthermore, the current signal output by the excitation channel is 1 mA, and the frequency is adjustable between 10K-100KHz.

[0010] Furthermore, the channel selection circuit uses four high-performance 16-channel analog switches to time-share multiplex the electrode array and control signal acquisition of multiple electrodes.

[0011] Furthermore, the acquisition channel is used to select two adjacent electrodes in the electrode array to measure the voltage value under the action of the channel selection circuit, and the voltage value is differentially amplified by the differential amplifier circuit, band-pass filtered by the band-pass filter circuit, amplitude adjusted by the amplitude adjustment circuit, and finally A / D acquisition is performed by the A / D acquisition circuit to convert the analog signal into a digital signal.

[0012] Furthermore, the electrode array includes 16 electrodes, which are distributed in a circular shape on the human body. The acquisition channel is used to measure the voltage of 16 groups of adjacent electrodes. The voltage measurement of each group of adjacent electrodes collects 13 voltage measurement values, and the voltage measurement of 16 groups of adjacent electrodes collects a total of 208 voltage measurement values.

[0013] Furthermore, the three-dimensional reconstruction system is used to preprocess the CT original image, and the preprocessing includes filtering and denoising; extracting the region of interest of the CT original image; segmenting the region of interest and extracting boundaries and contours; obtaining the discrete solution area, dividing the field into a finite number of units, and then deriving the control equation for the unit, after collecting all the units in the solution area, solving the system equation obtained by collecting the unit equations.

[0014] Furthermore, the three-dimensional reconstruction system is used to perform imaging using impedance information, applying current from the boundary node, injecting current from point a, assuming that the point is located on the node number m; current flows out from point b, assuming that the point is located on the node number g; point c is the measurement potential reference point, assuming that the point is located on the node number h; and assuming that m <g<h,将边界给定的条件结合到有限元方程中去,电导率均匀为 1 时得到下式:

[0015] ;

[0016] Where C refers to the potential distribution to be solved, V refers to the measured voltage, I refers to the injected current, and -I refers to the outflow current.

[0017] The above formula is solved using Gaussian elimination to obtain the potential distribution of the field, and image reconstruction is achieved based on the potential distribution of the field.

[0018] The present invention provides the following beneficial effects: The noninvasive cryoballoon positioning device for atrial fibrillation ablation offers high hardware compatibility, low hardware cost, and high safety by eliminating the need for prolonged exposure to harmful radiation during the procedure. The use of an electrode array for balloon positioning is simple and requires no user training. The use of impedance signals for balloon positioning offers excellent scalability and can be combined with other technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 A schematic diagram of a non-invasive positioning device for atrial fibrillation ablation cryoballoon provided by an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of an impedance testing circuit provided by an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of an electrode array using adjacent driving mode;

[0023] Figure 4 Schematic diagram of the current injection finite element node;

[0024] Figure 5 This is a typical triangle element diagram. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The technical solutions provided by each embodiment of the present invention are described in detail below in conjunction with the drawings.

[0026] See also Figure 1 An embodiment of the present invention provides a non-invasive positioning device for atrial fibrillation ablation cryoballoon, comprising: a main controller 1, an impedance testing circuit 2, a three-dimensional reconstruction system 3, a channel selection circuit 4 and an electrode array 5; the main controller 1 is connected to the impedance testing circuit 2, the impedance testing circuit 2 is connected to the channel selection circuit 4, the channel selection circuit 4 is connected to the electrode array 5, the three-dimensional reconstruction system 3 is connected to the main controller 1, and the electrode array 5 is arranged on the surface of the human body.

[0027] The impedance testing circuit is used to select a channel using the channel selection circuit to measure the impedance information of the electrode array.

[0028] See also Figure 2 The impedance test circuit includes an excitation channel and an acquisition channel, which are connected to the electrode array via a channel selection circuit. The excitation channel includes a DDS waveform generator 21 and a voltage-controlled constant current source circuit 22. The main controller 1 is connected to the DDS waveform generator 21, which is in turn connected to the voltage-controlled constant current source circuit 22. The DDS waveform generator 21 is used to generate a voltage signal, and the voltage-controlled constant current source circuit 22 is used to convert the voltage signal into a current signal. The current signal output by the excitation channel is 1 mA, and the frequency is adjustable between 10K and 100KHz.

[0029] The DDS waveform generator can be designed using the Analog Devices AD9833 or a similar chip. A safe current excitation generates a current field within human tissue. Due to the impedance characteristics of human tissue, a voltage difference inevitably forms on the skin surface. The acquisition channel's primary function is to measure this voltage difference. Using analog switches, it selects two adjacent electrodes for differential amplification, bandpass filtering, offset adjustment, and other conditioning circuits. Finally, A / D acquisition is performed to convert the analog signal into a digital signal.

[0030] Specifically, the acquisition channel includes a differential amplifier circuit 23, a bandpass filter circuit 24, an amplitude adjustment circuit 25, and an A / D acquisition circuit 26. The differential amplifier circuit 23 is connected to the bandpass filter circuit 24, which is connected to the amplitude adjustment circuit 25. The amplitude adjustment circuit 25 is connected to the A / D acquisition circuit 26, which is connected to the main controller 1. The acquisition channel is used, under the control of the channel selection circuit, to select two adjacent electrodes in the electrode array to measure the voltage value. The voltage value is then differentially amplified by the differential amplifier circuit, bandpass filtered by the bandpass filter circuit, and amplitude adjusted by the amplitude adjustment circuit. Finally, the A / D acquisition circuit performs A / D acquisition and converts the analog signal into a digital signal.

[0031] The channel selection circuit uses four high-performance 16-channel analog switches to time-share multiplex the electrode array and control the signal acquisition of multiple electrodes.

[0032] Electrode array design Figure 3 As shown, the electrode array 5 includes 16 electrodes, which are distributed in a circular shape on the human body and adopt an adjacent driving mode. Figure 3 In case A, the current flows into the human tissue from electrode 2 and flows out from electrode 1, so the current density at electrodes 1 and 2 is the largest and decays symmetrically to the surrounding areas. The remaining electrodes 3 to 16 can obtain the measured voltages of 13 adjacent electrodes, among which the voltages of adjacent electrodes 3-4 and adjacent electrodes 15-16 are the largest and decay toward adjacent electrodes 9-10, and the voltage of adjacent electrodes 9-10 is the smallest. Figure 3 In case B, the current flows into electrode 3 and out of electrode 2. The voltage of adjacent electrodes is measured from electrode 4 to electrode 1 in a clockwise direction, and 13 voltage data can be obtained.

[0033] The acquisition channel is used to measure the voltages of 16 groups of adjacent electrodes. The voltage measurement of each group of adjacent electrodes acquires 13 voltage measurement values, and a total of 208 voltage measurement values ​​are acquired from the voltage measurement of the 16 groups of adjacent electrodes.

[0034] The main controller is used to send the impedance information to the 3D reconstruction system. The collected impedance information is sent by the main controller to the 3D reconstruction system via the serial port to perform tissue modeling near the balloon, thereby achieving balloon positioning.

[0035] The three-dimensional reconstruction system is used to receive impedance information, reconstruct a boundary model based on prior information of the CT image, solve the distribution of conductivity changes in the electrode array according to the impedance information, and realize the positioning of the balloon according to the distribution of conductivity changes.

[0036] The three-dimensional reconstruction system is used to preprocess the original CT image, which includes filtering and denoising; extract the region of interest of the original CT image; segment the region of interest and extract the boundaries and contours; obtain the discrete solution area, divide the field into a finite number of units, and then derive the control equations for the units. After collecting all the units in the solution area, the system equations obtained by collecting the unit equations are solved.

[0037] The extracted boundaries and contours are used for impedance image reconstruction and region segmentation. The field refers to the area to be reconstructed, and the discrete solution area refers to the finite discretization of the area.

[0038] The process of deriving the governing equations for a cell is as follows: Find the internal potential V of cell e e Then, we find the correlation between the potential distribution of each unit in the field, so that the potential is continuous at the boundary of adjacent units. The approximate solution of the entire field is as follows:

[0039] ;

[0040] Where N is the number of triangle elements in the entire field; x, y are the coordinates of unit e, and the potential V in a single unit is e The approximate polynomial function of is shown below:

[0041] ;

[0042] Where a, b, and c are the coefficients to be determined.

[0043] Typical triangular elements such as Figure 5 As shown, Figure 5 Medium V e1 ,V e2 ,V e3 are the potentials on nodes 1, 2, and 3 respectively.

[0044] ;

[0045] Substituting into

[0046] ;

[0047] Substituting the Laplace equation into the equation, we can get:

[0048] ;

[0049] [C (e) ]Matrix is ​​the element coefficient matrix, usually called stiffness matrix in structural analysis. [C (e) The matrix is ​​the coupling between nodes i and j. This derives the governing equations for the element.

[0050] See also Figure 4 , the three-dimensional reconstruction system is used to use impedance information for imaging, applying current from the boundary node, injecting current from point a, assuming that the point is located on the node number m; current flows out from point b, assuming that the point is located on the node number g; point c is the reference point for measuring potential, assuming that the point is located on the node number h; and assuming that m <g<h,将边界给定的条件结合到有限元方程中去,电导率均匀为 1 时得到下式:

[0051] ;

[0052] Where C refers to the potential distribution to be solved, V refers to the measured voltage, I refers to the injected current, and -I refers to the outflow current.

[0053] The above formula is solved using Gaussian elimination to obtain the potential distribution of the field, and image reconstruction is achieved based on the potential distribution of the field.

[0054] The above-described embodiments of the present invention do not limit the protection scope of the present invention.

Claims

1. A non-invasive positioning device for atrial fibrillation ablation cryoballoon, characterized in that: Comprising: A main controller (1), an impedance test circuit (2), a three-dimensional reconstruction system (3), a channel selection circuit (4), and an electrode array (5); the main controller (1) is connected to the impedance test circuit (2), the impedance test circuit (2) is connected to the channel selection circuit (4), the channel selection circuit (4) is connected to the electrode array (5), the three-dimensional reconstruction system (3) is connected to the main controller (1), and the electrode array (5) is arranged on the body surface of a human body; The impedance test circuit is configured to select a channel by using the channel selection circuit and measure the impedance information of the electrode array; The main controller is configured to send the impedance information to the three-dimensional reconstruction system; The three-dimensional reconstruction system is configured to receive the impedance information, perform boundary model reconstruction based on the prior information of the CT image, solve the distribution of the conductivity change in the electrode array according to the impedance information, and realize the positioning of the balloon according to the distribution of the conductivity change; The three-dimensional reconstruction system is configured to perform imaging by using the impedance information, apply a current from a boundary node, inject a current at point a, assuming that this point is on the m-th number of the node label; the current flows out at point b, assuming that this point is on the g-th number of the node label; point c is the measurement potential reference point, assuming that this point is on the h-th number of the node label; and assuming m < g < h, combine the boundary given conditions into the finite element equation, and when the conductivity is uniformly 1, the following formula is obtained: In the formula, C refers to the potential distribution to be solved, V refers to the measured voltage, I refers to the injected current, and -I refers to the outflow current; Solve the above formula by using Gaussian elimination to obtain the potential distribution of the field domain, and realize image reconstruction according to the potential distribution of the field domain.

2. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 1, characterized in that: The impedance test circuit includes an excitation channel and a collection channel, and the excitation channel and the collection channel are connected to the electrode array through the channel selection circuit; The excitation channel includes a DDS waveform generator (21) and a voltage-controlled constant current source circuit (22), the main controller (1) is connected to the DDS waveform generator (21), and the DDS waveform generator (21) is connected to the voltage-controlled constant current source circuit (22); The collection channel includes a differential amplifier circuit (23), a band-pass filter circuit ( 3. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 2, characterized in that: ​ 4. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 2, characterized in that: ​ 5. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 1, characterized in that: ​ 6. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 2, characterized in that: The acquisition channel is used to select two adjacent electrodes in the electrode array to measure the voltage value under the action of the channel selection circuit, and the voltage value is differentially amplified by the differential amplifier circuit, band-pass filtered by the band-pass filter circuit, amplitude adjusted by the amplitude adjustment circuit, and finally A / D acquisition is performed by the A / D acquisition circuit to convert the analog signal into a digital signal.

7. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 6, characterized in that: The electrode array (5) includes 16 electrodes, which are distributed in a circular shape on the human body. The acquisition channel is used to measure the voltages of 16 groups of adjacent electrodes. The voltage measurement acquisition of each group of adjacent electrodes obtains 13 voltage measurement values, and the voltage measurement of the 16 groups of adjacent electrodes acquires a total of 208 voltage measurement values.

8. The non-invasive positioning device for atrial fibrillation ablation cryoballoon according to claim 1, characterized in that: The three-dimensional reconstruction system is used to preprocess the CT original image, which includes filtering and denoising; extract the region of interest of the CT original image; segment the region of interest and extract the boundaries and contours; obtain the discrete solution area, divide the field into a finite number of units, and then derive the control equation for the unit. After collecting all the units in the solution area, the system equation obtained by collecting the unit equations is solved.

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