CN114305687A

CN114305687A - Permanent magnet navigation system

Info

Publication number: CN114305687A
Application number: CN202111568825.XA
Authority: CN
Inventors: 卢才义
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-12-21
Filing date: 2021-12-21
Publication date: 2022-04-12

Abstract

The invention discloses a permanent magnetic navigation system, comprising: the magnetic field generating and controlling device comprises a permanent magnet and a permanent magnet control part which are vertically arranged; the generating device supporting part comprises a supporting crank arm, a supporting crank arm lifting device and a base, wherein the permanent magnet is connected with two ends of the supporting crank arm, and the supporting crank arm is connected with the base. According to the invention, the weight and the volume of the navigation permanent magnet are greatly reduced by the modes of vertical magnet layout, adaptive pulsed electric field ablation, upper magnet position optimization design, simplified numerical control motor drive, catheter micro-magnet optimization and the like, the number and the power of drive motors required by the operation of the permanent magnet are reduced, and the navigation precision and the navigation efficiency are improved.

Description

Permanent magnet navigation system

Technical Field

The invention relates to the technical field of medical instruments, in particular to a permanent magnet navigation system.

Background

The existing equipment of the cardiac interventional magnetic navigation system usually adopts permanent magnetic navigation or electromagnetic navigation;

permanent magnet navigation systems, such as the navigation device genetics RMN from Stereotaxis, usa, have the following basic implementation scheme: 1. two mushroom-shaped combined permanent magnets are respectively arranged on two sides of the chest of a patient to construct a navigation magnetic field, and the center points of the magnets are flush with the center point of the heart of the patient. 2. The front and back positions of the chest of the patient are reserved for placing an image intensifier (the front chest) and an X-ray bulb generator (the back) of the digital blood vessel subtraction device. 3. The numerical control motor group is adopted to operate a single magnet, so that the three-dimensional motion in 5 directions is realized: up and down, front and back, left and right slant and rotation. 4. The cooperative operation of the two magnets is subject to the parallelogram law of the navigation magnetic field.

The defects are as follows: 1. because the front and back space of the chest of the patient is occupied by the digital subtraction equipment, the navigation magnets can only be positioned at two sides of the chest of the patient, the distance between the navigation magnets and the operation heart cavity is increased, and the distance between the magnets and the operation heart cavity is further increased under the influence of the arms at two sides of the chest of the patient and the width of the catheter treatment bed. For the above reasons, the weight and volume of the navigation magnet are inevitably increased. 2. The increase of the weight of the navigation magnet influences the navigation speed, precision and efficiency on one hand, and obviously increases the power and the number of the driving motors on the other hand, simultaneously improves the floor bearing requirements on the construction and the use of a conduit room, and increases the noise of equipment. 3. The horizontal floor-type layout of the navigation magnet occupies the best operation position and space, and influences the operation and emergency operation of medical personnel. 4. The increase of the magnetic field intensity leads to the increase of the interference of the permanent magnetic field to the environment of the conduit room, and the difficulty of magnetic protection and magnetic shielding of related equipment of the conduit room is improved. 5. Due to the adoption of the dynamically changing composite magnetic field navigation mode, three difficulties need to be overcome for the motion control of the navigation magnet: firstly, the requirement on the space running direction and the angle of a single magnet is high, and a plurality of driving motors are required to meet the requirement. And secondly, different complex algorithms are needed for the coordination control of the two magnets, so that the complexity of related control hardware and software is increased. Thirdly, the comprehensive field intensity and direction of the composite magnetic field need to be dynamically measured so as to meet the navigation requirement by driving the change of the actual composite magnetic field through the magnitude and direction instruction of the target field intensity, and as a result, the complexity of field intensity control and navigation software is obviously increased.

Electromagnetic navigation systems, such as the navigation system of the Chinese academy of sciences institute and the navigation system of the Shaoxing Meiao magnetic medical science and technology company, require a sufficient number of electromagnetic coils in order to generate a strong enough electromagnetic field to completely cover the surgical heart cavity, and additional devices such as a cooling device and the like are required to be matched with the electromagnetic coils due to the particularity of the electromagnetic coils, so that the navigation magnet still has large weight and volume as a whole, and has high requirements on the strength and power of a supporting and driving device, otherwise the navigation accuracy, efficiency and safety are obviously affected.

Disclosure of Invention

The invention aims to provide a permanent magnet navigation system, which solves the problems that the navigation magnet of the existing navigation system is heavy in weight, large in volume and low in navigation precision and efficiency.

In one aspect of the present invention, there is provided a permanent magnet navigation system, comprising:

the magnetic field generating and controlling device comprises a permanent magnet and a permanent magnet control part which are vertically arranged;

the generating device supporting part comprises a supporting crank arm, a supporting crank arm lifting device and a base, wherein the permanent magnet is connected with two ends of the supporting crank arm, and the supporting crank arm is connected with the base.

The permanent magnet navigation system comprises an upper permanent magnet and a lower permanent magnet, wherein the weights of the upper permanent magnet and the lower permanent magnet are both less than 300 kg. Preferably, the permanent magnet is a cylinder; still preferably, the permanent magnet has a diameter of less than 80cm and a height of less than 30 cm. More preferably, the permanent magnet is made of a neodymium iron boron strong magnetic material, and the magnetic field intensity is less than 500 gauss.

The above permanent magnet navigation system, wherein, the system and the catheter pulsed electric field ablation device are used together, the weight of the upper permanent magnet and the lower permanent magnet is less than 200 kg.

The above permanent magnet navigation system, wherein, the axial working distance of the upper permanent magnet is less than the axial working distance of the lower permanent magnet. The axial working distance of the upper permanent magnet is the distance from the upper permanent magnet to the origin before the navigation system starts to work, the axial working distance of the lower permanent magnet is the distance from the lower permanent magnet to the origin before the navigation system starts to work, and the origin is the midpoint of the heart of the patient. Preferably, the axial working distance of the upper permanent magnet is 11cm, and the axial working distance of the lower permanent magnet is 17 cm.

The above permanent magnet navigation system, wherein the weight of the upper permanent magnet is less than the weight of the lower permanent magnet, and the weight of the upper permanent magnet is less than 100 kg.

In the above permanent magnet navigation system, the permanent magnet control part includes two sets of X-axis drive motors, Y-axis drive motors, Z-axis drive motors and sliding support parts corresponding to the drive motors, which are vertically arranged. Preferably, the sliding support part includes a support arm and a moving part; still preferably, the moving part is movably fixed at the top to the top of the support arm and at the bottom to the support arm for fixing and suspending the magnet or other shaft. Still preferably, the distribution of the X, Y, Z axis moving part and the supporting arm of the upper permanent magnet is: the Y axis is uppermost, the X axis is in the middle, and the Z axis is lowermost. The distribution of the lower permanent magnets is opposite to that described above.

The above permanent magnet navigation system, wherein the sliding support component includes a support arm and a moving component, and each driving motor is connected to the moving component to drive the moving component to move on the support arm.

The permanent magnet navigation system, wherein, support the crank arm and be C form crank arm, it is provided with support crank arm elevating gear to support the crank arm middle part, support crank arm elevating gear will support the crank arm and divide into and support crank arm and lower support crank arm, support crank arm elevating gear by crank arm lifting motor drive.

The permanent magnet navigation system comprises a base, a built-in navigation host, a power supply, a base lifting device, a base moving motor and a base guiding device, wherein the built-in navigation host is in electric signal connection with the X-axis driving motor, the Y-axis driving motor, the Z-axis driving motor, the crank arm lifting motor, the base moving motor and the base guiding device, and the base driving motor is connected with the base guiding device.

The permanent magnet navigation system as described above, wherein the base guide apparatus comprises a steering wheel and a driving wheel. Preferably, the steering wheel and the driving wheel are provided with brake devices.

The permanent magnet navigation system guides the catheter to move and position in a composite magnetic field midpoint navigation mode, and performs navigation according to the following process:

(1) constructing a surgical heart cavity three-dimensional navigation coordinate system;

(2) presetting a spherical navigation point of an operation heart cavity;

(3) establishing a general calculation formula of the coordinate parameters of the navigation points;

(4) establishing a general calculation formula of two-point navigation parameters;

(5) and guiding the flexible catheter to complete the navigation task according to the navigation instruction.

Advantageous effects

The permanent magnet navigation system realizes the portability of the permanent magnet navigation system through technical innovation in four aspects:

1. the navigation magnet comprehensive weight reduction technology. (1) The navigation magnet layout reduces weight. (2) The navigation magnetic field is adaptive to weight reduction. (3) The navigation magnetic field optimizes weight reduction. (4) The numerical control motor drives to simplify and reduce weight. (5) The catheter micro-magnet optimizes weight reduction.

2. Navigation magnetic field optimization techniques. (1) The axial working distance of the upper magnet and the lower magnet is set individually. 2. The working distance between the upper and lower magnets and the working chamber is set asymmetrically.

3. Navigation coordinate simplification techniques. (1) And constructing a three-dimensional navigation coordinate system of the operative heart cavity. (2) Presetting a spherical navigation point of the surgical heart cavity. (3) And establishing a general calculation formula of the coordinate parameters of the navigation points. (4) And establishing a general calculation formula of the two-point navigation parameters. (5) A composite magnetic field midpoint navigation technique.

4. Magnet drive optimization techniques. Due to the simplification of a three-dimensional coordinate system and a navigation mode, the power, the number and the driving mode of the navigation magnet numerical control motor are obviously optimized: (1) the maximum power of the motor is reduced to 150 watts from 500 watts, and the amplitude is reduced by 70%. (2) The number of the motors is reduced from 6 to 3, and the reduction is 50%.

(3) The driving mode is simple and quick.

Drawings

FIG. 1 is a schematic structural diagram of a permanent magnet navigation system according to the present invention;

FIG. 2 is a schematic structural diagram of a permanent magnet and a permanent magnet control component of the present invention;

FIG. 3 is a schematic view of the vertical coaxial layout of the permanent magnet and the permanent magnet control component structure of the present invention;

FIG. 4 is a schematic diagram of the present invention for determining the body surface projection points of the heart center point on the anterior chest wall.

The reference numbers are as follows:

the device comprises an upper permanent magnet hood 1, an upper supporting crank arm 2, a supporting crank arm lifting device 3, a lower supporting crank arm 4, a base 5, a base operation panel 6, a driving wheel 7, a steering wheel 8, a lower permanent magnet hood 9, a treatment couch 10, a chest cavity 11 of a patient, an in-vivo heart 12 of the patient, a Y-axis sliding supporting part 101, a Y-axis driving motor 102, an X-axis driving motor 103, an X-axis sliding supporting part 104, a Z-axis sliding supporting part 105, a Z-axis driving motor 106, an upper permanent magnet 107, a lower permanent magnet 108, a chest front 201 of the patient, a sternum angle 202, a sternum handle 203, a xiphoid process 204, a heart apex pulse strongest point 205, a projection 206 of a heart center point of the patient on the surface of an anterior chest wall, and a second intercostal 207 of a left sternal edge.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

Structure and operation mode of permanent magnet navigation system

Referring to fig. 1 to 4, the present embodiment provides a permanent magnet navigation system, which includes a magnetic field generating and controlling device, including two groups of permanent magnets and permanent magnet control components vertically arranged up and down; the generating device supporting component comprises a supporting crank arm, a supporting crank arm lifting device 3 and a base 5, wherein two groups of permanent magnets are connected with two ends of the supporting crank arm, and the supporting crank arm is connected with the base 5. Wherein the permanent magnets include an upper permanent magnet 107 and a lower permanent magnet 108.

The upper permanent magnet 107 is a cylinder, the diameter is less than 80cm, the height is less than 30cm, the weight is less than 120kg, neodymium iron boron strong magnetic material is adopted, the magnetic field intensity is less than 500 gauss, the upper permanent magnet is positioned in the upper permanent magnet hood 1 together with moving parts, the upper permanent magnet hood 1 is a long cylinder, the long axis is parallel to the treatment bed, the moving space of the upper permanent magnet 107 is reserved in the upper permanent magnet hood 1 by 20X 30X 20cm (an X axis, a Y axis and a Z axis), and the upper permanent magnet hood 1 is positioned at the top end of the upper part of the support crank arm and is connected with the support crank arm. The upper permanent magnet control part includes an X-axis drive motor 103, a Y-axis drive motor 102, a Z-axis drive motor 106, and a slide support part corresponding to each drive motor. The sliding support part comprises a support arm and a moving part, and a driving motor of each shaft is connected with the moving part corresponding to each shaft to drive the moving part of each shaft to move. Specifically, the driving motor can be a stepping motor, preferably a numerical control stepping motor, the supporting arm is a sliding rail, the moving part is a sliding block, and the stepping motor is in electric signal connection with the built-in navigation host and controls the movement through the built-in navigation host; the distribution of the moving parts and the support arms of the three orthogonal axes X, Y, Z of the upper permanent magnet 107 is: the Y axis is uppermost, the X axis is in the middle, and the Z axis is lowermost. X, Y, Z the three driving motors are numerical control driving motors, which are driven by navigation instructions to operate at the same time, different speeds and directions and different three-dimensional coordinate distances, and can drive the upper permanent magnet 107 to move freely in three-dimensional space for positioning, thus realizing the free navigation of the midpoint of the navigation magnetic field on the spherical surface of the surgical heart cavity. The magnetic field surface of the upper permanent magnet 107 is downwards directed to the anterior chest wall of the patient, the midpoint of the magnetic field surface is directed to the body surface projection point of the midpoint of the heart of the patient on the anterior chest wall, and the magnetic field surface is provided with a receiver which can sense the positioning electrode which is stuck to the projection 206 of the central point of the heart of the patient on the body surface of the anterior chest wall so as to determine and adjust the initial position of the navigation magnetic field.

The lower permanent magnet 108 and the control components as well as the lower permanent magnet housing 9 are arranged in mirror image relation with the upper permanent magnet 107, the lower permanent magnet housing 9 being located at the top end of the lower part of the support crank arm. The magnetic field is directed upward toward the patient's posterior chest wall. The midpoint of the magnetic field surface points to the body surface projection point of the midpoint of the patient's heart on the posterior chest wall, is coaxial with the midpoint of the magnetic field surface of the upper permanent magnet 107, and synchronously sets and adjusts the initial position of the navigation magnetic field together with the upper permanent magnet 107. The lower permanent magnet 108 has a larger weight and volume than the upper permanent magnet 107, and therefore, has a larger magnetic field range and strength than the upper permanent magnet 107. The midpoint of the individual navigation magnetic field formed by the upper and lower permanent magnets is biased to one side of the upper magnet. The relative positions of the upper magnet and the lower magnet can be individually determined according to the spatial position of the heart of the patient, and once the relative positions are determined, the coaxial synchronous operation is always kept in the same operation. The lower permanent magnet 107 and the upper permanent magnet 108 form a coaxial homopolar mirror image magnet pair, and the individual composite navigation magnetic field is constructed together by individually adjusting the distance between the magnetic field surfaces of the two mirror image permanent magnets.

In the embodiment, the layout mode of the existing navigation magnets in the directions of the two sides of the chest of the patient is changed, and the navigation permanent magnets are designed to be in the layout mode in the directions of the chest and the back of the patient again.

The basic principle and the calculation method of weight reduction of the layout of the navigation permanent magnet are as follows: 1) the patient is in a horizontal position, the midpoint of the heart of the patient is taken as a calculation origin, and the average diameter of the heart sphere of the patient is set to be 8 cm. 2) The horizontal transverse diameter (lateral surface reaching the outer side of the upper arm of the patient) of the chest of the patient passing through the midpoint of the heart is 60cm on average, and the vertical longitudinal diameter is 30cm on average. 3) The horizontal transverse diameter and the vertical longitudinal diameter are asymmetric, and the horizontal transverse diameter passing through the midpoint of the heart is 50% longer than the vertical longitudinal diameter. 4) The layout of the navigation permanent magnet has the weight reduction effect: after the layout mode of the two permanent magnets is changed from the layout on two sides of the chest to the front-back layout of the chest, the weight of the navigation permanent magnet can be reduced by 50 percent, namely the weight of the navigation permanent magnet is reduced to below 300kg from 800kg of the conventional single navigation permanent magnet.

Compared with the catheter radio frequency ablation in the prior art, the permanent magnet navigation system of the embodiment is used together with the catheter pulsed electric field ablation device, the navigation purpose is only one, namely the direction of the head end of the catheter is changed, and the attaching force of the head end of the catheter and endocardial tissue is not required to be increased. Thus, by adapting different catheter ablation techniques, the weight of a single navigation magnet can be significantly reduced. The basic principle and the calculation method of the weight reduction of the navigation magnetic field adaptation comprise the following steps: 1) the effective tissue attaching force required by the catheter radio frequency ablation technology is 5-25 g, and the average force is 15 g. 2) When using the catheter pulse ablation technique, only the tip of the catheter needs to contact or be very close to the endocardial tissue, and no additional tissue apposition force is required at all. 3) The adaptive weight reduction effect of the navigation magnet is as follows: when cardiac magnetic navigation is mainly aimed at adapting the catheter pulse ablation technology, the working field intensity of the navigation magnetic field can be reduced from the current average 800 gauss to 400 gauss, so that the weight of a single navigation magnet can be further reduced from 300kg to below 200 kg.

This example also fully considers that in humans, where the body's heart is located within the anterior mediastinum of the chest cavity, the distance from the midpoint of the heart to the surface of the anterior chest is significantly different from the distance to the surface of the back. Therefore, the upper permanent magnet 107 positioned at the chest of the patient is further lightened by adopting the asymmetric composite magnetic field design for the navigation working magnetic field.

The basic principle and the calculation method for optimizing weight reduction of the navigation magnetic field comprise the following steps: 1) the patient is in a horizontal position, the midpoint of the heart of the patient is taken as a calculation origin, and the average diameter of the heart sphere of the patient is set to be 8 cm. 2) The horizontal transverse diameter (lateral surface reaching the outer side of the upper arm of the patient) of the chest of the patient passing through the midpoint of the heart is 60cm on average, and the vertical longitudinal diameter is 30cm on average. 3) The longitudinal diameters are asymmetrical. The posterior longitudinal diameter from the midpoint of the heart to the back surface of the patient is 50% longer than the anterior longitudinal diameter to the anterior chest surface. 4) Optimizing a weight reduction effect of the navigation magnetic field: according to the principle that the front longitudinal diameter is shorter than the rear longitudinal diameter by 50%, the weight of the permanent upper magnet 107 positioned at the front chest part can be further reduced by 50% by designing the asymmetric composite magnetic field, namely, the weight is reduced from 200kg to less than 100 kg.

The specific implementation scheme of the asymmetric layout of the upper permanent magnet and the lower permanent magnet is as follows:

1) asymmetric setting of axial working distance of upper and lower magnets

a. Heart center distance from anterior and posterior chest surface. The anteroposterior diameter of a normal adult heart is 6cm on average according to the spatial position of the intracorporeal state in the chest. The straight-line distance from the anterior wall of the heart to the surface of the anterior chest is 3cm on average, and the straight-line distance from the posterior wall of the heart to the surface of the posterior back is 6cm on average. Based on this calculation, the straight line distance from the heart center to the chest body surface is on average 6cm, and the straight line distance from the heart center to the back body surface is on average 9 cm.

b. The reserved safe distance between the surface of the magnet and the body surface of the patient is as follows: 2cm above and below.

c. The average thickness of the treatment bed board is 5 cm.

d. The up-and-down movement working stroke of the magnet: the mean is 6cm calculated according to the anterior-posterior diameter of the covered heart.

e. And calculating the axial working distance of the upper permanent magnet and the lower permanent magnet. With the heart center as the work origin, the starting position of the magnet is set relative to the origin before the navigation system starts working. The distance between the upper permanent magnet 107 and the origin is half of the anteroposterior diameter of the heart (3cm), the distance between the anterior wall of the heart and the anterior chest body surface is (3cm), the reserved safe distance is (2cm), and the half of the anteroposterior diameter working stroke of the heart (3cm) is 11 cm. The distance from the lower permanent magnet 108 to the origin is half of the anteroposterior diameter of the heart (3cm), the distance from the back wall of the heart to the body surface of the back (6cm), the thickness of the treatment bed plate (3cm), the reserved safe distance (2cm) and half of the anteroposterior diameter working stroke of the heart (3cm) is 17 cm. The axial working distance of the upper magnet and the lower magnet is 11cm +17cm and 28 cm.

2) Individualizing defining magnet working distances based on in vivo cardiac spatial localization

a. And determining the body surface projection point of the heart central point on the anterior chest wall. Determining the projection point of the heart center point on the chest body surface according to the body surface bony mark: (1) determining a second intercostal space according to the sternum angle, and determining a projection point at the upper right of the heart at a position 2cm away from the right edge of the horizontal sternum; (2) determining a lower left projection point of the heart according to the apical pulsation; (3) connecting the 2 points to obtain a heart body surface projection diagonal; (4) the middle point of the diagonal line is the projection point of the heart center point on the surface of the chest body; (5) the X-ray detectable site is adhered at this point for future use.

b. And determining the body surface projection point of the heart center point on the left chest wall. The height from the treatment bed surface. (1) The most obvious part of the heart beat is measured by a movable angle square to measure the vertical distance between the surface of the chest of the patient and the surface of the treatment bed; (2) subtracting 6cm from the distance to obtain the height of the heart center point from the treatment bed surface; (3) the X-ray detectable patch is stuck on the left chest wall of the patient at the height for standby.

calibrating the initial working position of the magnet. (1) The electrode detector positioned on the surface of the upper permanent magnet 107 automatically completes the horizontal position calibration of the initial working point; (2) and the electrode detector positioned on the inner side surface of the support crank arm automatically completes the vertical position calibration of the initial working point.

3) Weight reduction effect of asymmetric layout of upper permanent magnet and lower permanent magnet

The working distance of the lower permanent magnet 108 is 39.3% farther (28-17)/28 relative to the origin of the heart than the upper permanent magnet 107. Therefore, to keep the upper and lower permanent magnets at the same field strength at the origin of operation, the lower permanent magnet 108 needs to be 40% larger than the upper permanent magnet 107.

The support crank arm is a C-shaped crank arm, the notch of the C points to the left side of the treatment bed, the upper end of the C is connected with an upper permanent magnet 107Y-axis sliding support part 105, the lower end of the C is connected with a lower permanent magnet 108Y-axis sliding support part, the bottom of the C is connected with a lifting base 5, a support crank arm lifting device 3 is arranged in the middle of the support crank arm, and the support crank arm is divided into an upper support crank arm 2 and a lower support crank arm 4. The supporting crank arm lifting device 3 comprises a crank arm lifting shaft and a crank arm lifting motor, wherein the crank arm lifting shaft is driven by the crank arm lifting motor to move up and down and is used for individually adjusting the working height of the upper permanent magnet 107.

The base 5 comprises a built-in navigation host, a power supply, a base lifting device, a base moving motor and base guiding equipment, wherein the base lifting device comprises a base lifting shaft and a base lifting motor, is positioned in the middle of the base, is used for adjusting the height of the supporting crank arm, is matched with the lifting function of the treatment bed, and finely coordinates the initial position of the navigation magnetic field and the working height of the lower permanent magnet 108. The built-in navigation host is electrically connected with an X-axis driving motor 103, a Y-axis driving motor 102, a Z-axis driving motor 106, a crank arm lifting motor, a base moving motor and base guiding equipment, and the base moving motor is connected with the base guiding equipment. The base 5 is provided with an operation panel for operating the built-in navigation host from the outside and controlling the operation of the equipment connected with the built-in navigation host.

The base guiding device comprises a steering wheel 8 and a driving wheel 7, the base moving motor drives the driving wheel 7 to rotate, and the steering wheel 8 and the driving wheel 7 are both provided with a brake device for fixing the magnetic navigation system at a working position or a storage position.

In order to realize the free positioning and navigation of the flexible catheter guided by the composite navigation magnetic field on the spherical surface of the surgical heart cavity, the embodiment provides a composite magnetic field midpoint navigation technology, and aims to adopt a simplified three-dimensional coordinate system and an operation formula thereof to navigate according to the following processes:

determining coordinate orientation. Coordinate orientations are set according to frontal, sagittal and cross-sections of human anatomy. The X axis and the Y axis are positioned on the frontal plane, wherein the X axis takes the left side of the patient as the positive direction and the right side as the negative direction; the Y axis is positive on the head side and negative on the foot side of the patient. The X-axis and Z-axis lie in the cross-section, with the Z-axis being positive on the patient's forebreast and negative on the back. The Y and Z axes lie in the sagittal plane, with the positive and negative orientations being the same as described above. And carrying out three-dimensional positioning on the three-dimensional image of the operative cardiac cavity of the patient according to the coordinate position to construct a three-dimensional navigation coordinate system.

Determining the origin of the coordinates. I.e. the central point of the operative heart cavity. The determination method comprises the following steps: 1) respectively measuring X, Y, Z shaft maximum inner diameters on the operation heart cavities which are positioned in three-dimensional mode; 2) comparing and selecting the maximum inner diameter of the three as the first inner diameter passing through the origin; 3) comparing and selecting the largest inner diameter of the other two as a first plane perpendicular to the original point inner diameter; 4) retrieving the maximum inner diameter on the plane, wherein the axial direction is intersected with the first maximum inner diameter; 5) the intersection point of the two maximum inner diameters is the center point of the heart cavity for operation and is also the origin of coordinates.

And constructing an individual three-dimensional coordinate system. And a 3 rd inner diameter line is vertically led out from the coordinate origin and is intersected with the spherical surface of the surgical heart cavity, so that a complete individualized three-dimensional navigation coordinate system is formed. The construction of the navigation coordinate system can be pre-constructed on the simulation operation heart cavity three-dimensional image with default system and revised actual parameters, and can also be pre-constructed on the actual operation heart cavity three-dimensional image to be fused.

(2) Presetting a spherical navigation point of an operation heart cavity;

on the spherical surface of the operation heart cavity with the built three-dimensional coordinates, spherical coordinate navigation points are built with the resolution of square millimeters, and the navigation points are simultaneously subjected to computer coding. These navigation points are mainly used for three purposes: navigation is carried out on an initial starting point. When the system first identifies a magnetic catheter located within the surgical heart chamber, the location of the catheter tip will be automatically identified as the navigation initiation point. And ② navigation starting points. When the catheter leaves the initial navigation point according to the operation instruction of the operator and reaches the first navigation target point, the target point is defaulted as the first navigation starting point. And thirdly, navigating the target point. The navigation track and the navigation parameters are formed between the command selection issued by the operator and the preorder navigation starting point.

establishing a general calculation formula of basic coordinates of navigation points so as to be used as a navigation starting point and a navigation target point in the actual navigation process.

Establishing a calculation formula of basic navigation parameters of the navigation points, wherein the calculation formula mainly comprises the projection distance and the direction of the navigation points on the three-dimensional coordinates.

and converting navigation point functions. All navigation points are divided into navigation initial starting points (system automatic identification), navigation starting points and navigation target points, and other navigation points except the navigation initial starting points are switched at any time according to different purposes. When the specified navigation between two points is instructed to be finished, the navigation target point automatically becomes the starting point of the next navigation action.

And secondly, calculating the navigation distance and direction parameters of the target point. The projection distance of the two points on each orthogonal coordinate axis of the three-dimensional coordinate is matched with the projection direction pointing to the navigation target point, namely the navigation distance and the direction instruction parameter of the target point.

And thirdly, calculating a target point navigation time parameter. The maximum navigation time between two points is the maximum projection distance of two navigation points on three orthogonal coordinate axes/the maximum rotating speed of the numerical control motor. And the navigation time of other coordinates is the projection distance of each coordinate/the maximum rotating speed of the numerical control motor.

And fourthly, calculating the target point navigation speed parameter. Namely, the working rotating speed of the numerical control motor on three orthogonal coordinate axes is calculated by the following formula: the working rotating speed of the numerical control motor is equal to the projection distance of two navigation points on respective orthogonal coordinate axes/the maximum navigation time between the two points.

(5) And guiding the flexible catheter to complete the navigation task according to the navigation instruction. The built-in navigation host drives X, Y, Z shaft three numerical control driving motors according to the navigation instruction of the operator, the three-dimensional coordinate system and the operation formula thereof, and guides the flexible catheter to complete the navigation task.

The asymmetric composite magnetic field midpoint navigation mode of the embodiment greatly reduces the number and power of the driving motors and optimizes the operation mode, thereby further reducing the weight of the navigation magnet control component, saving the energy consumption and simplifying the operation mode.

In terms of quantity, the existing cardiac magnetic navigation equipment adopts 5 numerical control motors to drive the navigation magnet, and the 5 numerical control motors are responsible for 5 different motion directions, including lifting, advancing and retreating, translation, inclination and rotation. The computer controls different movement combination modes between the two navigation magnets to generate the direction change of the comprehensive vector of the composite magnetic field, thereby realizing the three-dimensional navigation of the head end direction of the catheter in the heart cavity. This way of controlling the navigation magnet we call the complex magnetic field vector navigation mode. According to the above, the present embodiment synchronously operates two navigation magnets on X, Y, Z three-dimensional coordinate axes according to the spherical stereo navigation principle, so as to control the working center point of the asymmetric composite magnetic field to freely move between any navigation points on the three-dimensional sphere of the surgical heart chamber, and the number of the driving motors of the navigation magnets can be reduced by nearly 50%, i.e. the number of the motors driving a single navigation magnet is reduced from 5 to 3, thereby further reducing the total weight of the navigation magnets.

In terms of power, the power of the numerical control motor driving the navigation magnet is obviously reduced due to the obvious lightness of the navigation magnet. According to calculation, when the weight of a single navigation magnet is reduced from 800kg to 200kg, the maximum power of the numerical control motor can be reduced from 500 watts to 150 watts at present, and the reduction amplitude reaches 70%.

The specific calculation process is as follows:

1) estimation of motor power required to drive 800kg navigation magnet:

F＝mg，P＝FV

P＝800*9.8*2.5/60≈326.67W

taking into account motor efficiency and transmission efficiency factors:

the following needs to be used: 326.67 x 1.5 ≈ 500W motor.

2) Estimation of motor power required to drive 200kg of navigation magnet:

F＝mg，P＝FV

P＝200*9.8*2.5/60≈81.67W

considering motor efficiency and transmission system efficiency factors:

the following needs to be used: 81.67 x 1.8 ≈ 150W motor.

3) The descending amplitude of the motor power after the drive optimization:

(500-150)/500＝70％

in the aspect of optimizing the running mode of the numerical control motor,

(1) the built-in navigation host of the embodiment automatically identifies the initial navigation starting point (namely the initial position of the head end of the flexible magnetic catheter in the surgical cardiac chamber) according to the three-dimensional coordinate system and the operation formula thereof.

(2) The operator selects the navigation target point. After the navigation process is finished, the point automatically becomes a subsequent navigation starting point, and so on.

(3) The operator gives a navigation instruction.

(4) The built-in navigation host automatically retrieves and calculates the direction and absolute distance of the navigation magnetic field to move on the three-dimensional coordinates.

(5) The built-in navigation host calculates the total navigation time according to the maximum working speed of the driving motor and the maximum moving distance on the axis of the three-dimensional coordinate X, Y, Z.

(6) The motor speeds for the other 2 axes are calculated from the total navigation time.

(7) And synchronously starting the driving motor group in a three-dimensional coordinate axis according to the three-dimensional coordinate navigation parameter and the driving motor parameter, driving the navigation magnet to change the navigation midpoint of the composite magnetic field to reach a navigation target point, and driving the flexible magnetic guide pipe to accurately move to the navigation target point.

(8) If the available length of the flexible magnetic catheter is shorter than the length needed to reach the navigation target, the catheter tip will only change direction and cannot move to reach the navigation target.

(9) When the operator operates the catheter driver to change the available length of the catheter in the body, the head end of the catheter directly reaches the navigation target point according to the positioning requirement of the navigation target point.

(10) An operator can optimize or adjust the positioning quality of the catheter head end through the catheter electrophysiological parameters and the catheter three-dimensional posture.

Further, the present embodiments also improve the outer diameter of the electrophysiology ablation catheter. The specific principle is as follows:

since cardiac magnetic navigation is accomplished by the cooperation of a flexible magnetic catheter located within the surgical heart cavity. The main matching mode is that the micro-magnet group is arranged at the head end of the catheter, so that when the head end of the catheter enters the navigation magnetic field, the navigation magnet and the navigation magnetic field thereof can drive the flexible catheter to complete three-dimensional positioning navigation due to the interaction of the catheter micro-magnet and the navigation magnetic field.

The interaction and response speed of the catheter micro-magnet and the navigation magnetic field can be optimized by changing the appearance, weight, volume and combination mode of the catheter head end micro-magnet. The basic rule is as follows: (1) the larger the weight and volume of the catheter micro-magnet, the more the number of the catheter micro-magnets is, the stronger the interaction with the navigation magnetic field is, and the lighter and smaller the navigation magnet which drives the catheter to realize navigation positioning can be made. (2) Under the condition of ensuring that the cardiac navigation condition and effect are not changed, the weight and the quantity of the catheter micro-magnets are increased, the strength of the navigation magnetic field can be correspondingly reduced, and the purpose of reducing the weight of the navigation magnet is further achieved.

The weight of a catheter micro-magnet is related to its length on the one hand, but a more important factor is its outer diameter. The size of the outer diameter of the catheter micro-magnet is mainly controlled by the outer diameter of the catheter. The size of the outer diameter of the catheter is mainly influenced by the catheter access, the surgical purpose, the manufacturing materials and the process.

The existing adult electrophysiology ablation catheter mainly has two specifications of 7F and 8F in outer diameter, and the design idea mainly comes from femoral vein and femoral artery access of the traditional electrophysiology technology. To reduce peripheral arterial complications and reduce damage to the aortic valve, ablation catheters for the femoral retrograde approach are typically designed at 7F and for the femoral venous approach at 8F, the latter primarily for improved maneuverability and mapping and ablation efficiency.

However, with the development of electrophysiological intervention techniques, treatment of left heart system arrhythmias is increasingly being accomplished by interatrial puncture, thereby avoiding complications of femoral access and injury of the aortic valve retrograde transvalveolus. As the femoral vein path has the characteristics of thick diameter, short path, straight walking and direct blood flow direction, the femoral vein path is one of ideal paths when the aim of professional diagnosis and treatment is fulfilled by increasing the outer diameter of the catheter.

The outer diameter of the flexible magnetic catheter for the heart which is clinically adopted at present is 8F.

This embodiment increases the catheter outer diameter, for example from 8F to 9, 10 or 11F (1F-0.33 mm), and even with the length of the magnets kept constant, the weight and volume can be significantly increased simply by increasing the outer diameter of the catheter micro-magnet. The degree of increase is calculated as follows:

1. the outer diameter of the catheter is increased by an F number (e.g., from 8F to 9F), and the weight gain percentage of the catheter micro-magnet is: (9-8) × 0.033/8 × 0.33 × 100% ═ 12.5%.

2. Catheter outer diameter is increased by one F number (e.g., from 8F to 9F), the volume increase percentage of the catheter micro-magnet: (9 × 0.33/2 × pi h-8 × 0.33/2 × pi h) — 100% — 9 × 0.33/2 × pi h%. Where h is the length of the catheter micro-magnet.

3. The increase of the weight and the volume of the catheter micro-magnet can improve the reactivity of the catheter micro-magnet to the navigation magnetic field, thereby achieving the purpose of achieving the same navigation effect by using a smaller navigation magnetic field and a lighter navigation magnet.

4. As the outer diameter of the flexible magnetic catheter increases, the surface area of the catheter tip end electrode will correspondingly increase, thereby also improving the efficiency of electrophysiological mapping and ablation.

Second, the work flow of the permanent magnetic navigation system

1. The patient lies down on the catheterization laboratory treatment couch, exposing the left anterior chest wall and the side chest wall.

2. Determining a second intercostal space according to the sternal angle, and marking a cardiac shadow upper right point at a position 2cm away from the left edge of the intercostal sternum; marking the left lower point of the cardiac shadow at the position 1cm below the most obvious part of the cardiac apex pulsation; the detectable site is affixed at the midpoint of the line connecting the two points.

3. The chest wall thickness of the patient is measured at the most obvious position of the heart through the apex of the heart, and the height of the center point of the heart from the treatment bed surface is obtained by subtracting 6cm from the value.

4. And all other electrophysiological body surface electrodes are pasted, and reliable pasting is confirmed.

5. Sterilizing and paving in a conventional operation, and establishing a sterile operation environment.

6. After local anesthesia, percutaneous vascular puncture is carried out, and a sheath catheter and a flexible magnetic catheter are sent into the percutaneous vascular puncture to establish operation conditions.

7. The height of the treatment bed is adjusted to reach the working height range of the permanent magnet navigation system.

8. And removing the protective cover of the permanent magnet navigation system, starting a power supply, and performing system self-inspection.

9. The operation panel is operated to guide the permanent magnet navigation system to move to the left side of the treatment couch, so that the surface of the upper permanent magnet 107 is approximately aligned with the projection 206 of the center point of the heart of the patient on the surface of the anterior chest wall, and the brake fixing permanent magnet navigation system of the driving wheel 7 and the steering wheel 8 at the lower part of the base 5 is started.

10. The upper magnet electrode detector detects the detectable positioning patch on the front chest wall of the patient, the automatic positioning function is started, and the permanent magnet navigation system automatically calibrates the initial working position of the magnet.

11. And starting navigation software, and controlling the magnet to complete the cardiac three-dimensional navigation operation by an operator through the built-in navigation host.

12. An operator clicks a target navigation point on a three-dimensional reconstruction image of a working heart cavity, the host computer calculates a three-dimensional navigation distance according to an axis X, Y, Z, then motor groups of an upper magnet and a lower magnet are synchronously driven according to motor combination, a navigation central point of the magnet is guided to accurately move to the position of the target navigation point, so that the head end of the magnetic catheter is driven to accurately point to the navigation point, and the head end of the catheter is accurately contacted with endocardium tissues at the navigation point under the coordination of a catheter advancing and retreating driver outside a patient body.

13. And by analogy, all navigation operations of the operation are completed.

14. And (5) closing the navigation software after the operation is finished, and withdrawing the brakes of the driving wheels 7 and the steering wheels 8.

15. The robot is driven to move to the storage position by manipulating the base operation panel 6.

16. The driving wheel 7 and the steering wheel 8 are started to brake to prevent the robot from being displaced accidentally.

17. And turning off the power supply and covering the protective cover.

In summary, the permanent magnet navigation system of the present invention has the following advantages:

1. because the weight and the volume of the navigation magnet are greatly reduced, the navigation precision and the navigation efficiency are obviously improved, and the motor power is reduced.

2. The magnetic navigation equipment is changed from fixed installation to free movement, and the use space of a catheter room is effectively released.

3. The navigation equipment can be actively adapted to the existing various catheter rooms, and the special construction of a large-scale magnetic navigation catheter room is not needed.

4. The magnetic navigation is not bound with DSA (Digital subtraction angiography) equipment any more, and becomes independent equipment, and the cost of the whole machine is greatly reduced.

5. The two navigation magnets synchronously run in a coaxial mode without changing relative distance, position and angle, and the number of driving motors required by the running magnets is obviously reduced.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A permanent magnet navigation system, comprising:

2. The permanent magnet navigation system of claim 1, wherein the permanent magnets comprise upper and lower permanent magnets each weighing less than 300 kg.

3. The permanent magnet navigation system of claim 2, wherein the upper and lower permanent magnets each weigh less than 200kg for use with a catheter pulsed electric field ablation device.

4. The permanent magnet navigation system of claim 2, wherein an axial working distance of the upper permanent magnet is less than an axial working distance of the lower permanent magnet.

5. The permanent magnet navigation system of claim 4, wherein the upper permanent magnet weighs less than the lower permanent magnet and the upper permanent magnet weighs less than 100 kg.

6. The permanent magnet navigation system of claim 1, wherein the permanent magnet control part comprises two sets of X-axis driving motor, Y-axis driving motor, Z-axis driving motor and sliding support part corresponding to each driving motor, which are vertically arranged.

7. The permanent magnet navigation system of claim 6 wherein the sliding support assembly includes a support arm and a motion assembly, each drive motor coupled to the motion assembly for driving the motion assembly on the support arm.

8. The permanent magnet navigation system of claim 1, wherein the support crank arm is a C-shaped crank arm, and a support crank arm lifting device is disposed in the middle of the support crank arm, and divides the support crank arm into an upper support crank arm and a lower support crank arm, and the support crank arm lifting device is driven by a crank arm lifting motor.

9. The permanent magnet navigation system of claim 1, wherein the base includes an inbuilt navigation host, a power supply, a base lifting device, a base moving motor and a base guiding device, the inbuilt navigation host is in electrical signal connection with the X-axis driving motor, the Y-axis driving motor, the Z-axis driving motor, the crank lifting motor, the base lifting motor and the base moving motor and the base guiding device, and the base driving motor is connected with the base guiding device.

10. The permanent magnet navigation system of claim 1, wherein the permanent magnet navigation system guides the catheter to move and position by using a composite magnetic field midpoint navigation mode, and the navigation is performed according to the following process:

(2) presetting a spherical navigation point of an operation heart cavity;