Disclosure of Invention
The invention aims to provide a flexible microwave ablation catheter, which is characterized in that a lantern-shaped cage-shaped supporting unit, a supporting tube and a metal column are matched, so that a radiation antenna is in a centered state in a blood vessel and is prevented from being curled, 360-degree uniform ablation around the blood vessel can be realized through the radiation antenna, and an electric field of a microwave ablation area is restrained through a choke unit, so that the ablation area approximates to a cylinder, and a tailing ablation area is prevented from ablating a non-target area.
The technical scheme adopted by the invention is as follows:
The utility model provides a flexible microwave ablation catheter, includes outer pipe, cooling tube and the coaxial cable that sets gradually from outside to interior, coaxial cable includes coaxial inner core, around coaxial first dielectric layer of the coaxial setting of inner core and around the coaxial outer conductor of the coaxial setting of first dielectric layer, the one end of coaxial inner core is provided with the radiation end, still includes:
The cage type supporting units are assembled inside the pipe wall of the outer pipe and comprise a plurality of high-strength fiber wires which are connected in a sliding mode in the pipe wall of the outer pipe, a plurality of guide outlets are formed in the outer side of the outer pipe, and the guide outlets are in one-to-one fit with the high-strength fiber wires;
a choke unit mounted on an outer side of the coaxial outer conductor;
The high-strength fiber filaments in the same cage type supporting unit slide out of the tube wall of the outer catheter to form a lantern-shaped structure, and the outer catheter can keep a central state in a blood vessel through the cage type supporting units.
In a preferred embodiment, the method further comprises:
the support tube is fixed at one end of the inner part of the outer catheter, a plurality of support ribs are arranged in the support tube, the cooling tube is fixedly connected with one end of the support tube, which is close to each other, and the radiation end penetrates through the inner part of the support tube;
The metal columns are assembled outside the radiation ends and are positioned in the support tubes, the radiation ends and the metal columns form a radiation antenna together, and the metal columns and the support ribs are in one-to-one correspondence;
in the transcatheter renal sympathetic nerve removing operation, the supporting tube and the plurality of metal posts are matched, so that the radiation antenna can be kept in a centered state inside the outer catheter, and the phenomenon that the radiation antenna is curled can be avoided.
In a preferred embodiment, the support tube is made of any one of the following materials: ABS, PTFE, PI, PEEK.
In a preferred scheme, the length of each metal column ranges from 1.5mm to 5mm, and the distance between two adjacent metal columns in the horizontal direction ranges from 2mm to 8mm.
In a preferred scheme, the choke unit comprises a second dielectric layer, a conductive layer and a metal ring, wherein the second dielectric layer is coaxially arranged on the outer side of the coaxial outer conductor, the conductive layer is coaxially arranged on the outer side of the second dielectric layer, the metal ring is assembled on the outer side of the supporting tube and is positioned at one end, far away from the supporting tube, of the second dielectric layer, and the conductive layer is electrically connected with the metal ring.
In a preferred scheme, the wall thickness of the second dielectric layer is L1, and the wall thickness of the metal ring is L2, wherein L2 is more than or equal to L1.
In a preferred embodiment, the material of the conductive layer is any one of the following materials: conductive adhesive, silver paste and metal flakes.
In a preferred embodiment, the length of the conductive layer is denoted as Lm,0.05λ0≤Lm≤0.2λ0, wherein λ0 represents the microwave wavelength in vacuum.
In a preferred embodiment, a protective film is disposed on the outer side of the choke unit, and the protective film is made of any one of the following materials: PTFE, PET.
The invention has the technical effects that:
According to the invention, the cage-shaped supporting unit in the working state is used for supporting the outer catheter, so that the outer catheter can be kept in a centered state in a blood vessel, and the radiation antenna on the coaxial inner core can be kept in the centered state in the blood vessel through the cooperation of the supporting tube and the metal column, so that the phenomenon of curling of the radiation antenna is avoided, 360-degree uniform ablation around the blood vessel can be realized through the radiation antenna, the ablation effect and the ablation efficiency are improved, and meanwhile, the cage-shaped supporting unit can not cause unsmooth blood flow, and the situation of acute thrombus of a patient is avoided;
According to the invention, the blood flowing in the blood vessel is utilized to cool the blood vessel wall, the circulating flowing refrigerant is utilized to cool the radiation antenna, so that the refrigerant does not enter the body, the blood vessel pressure is reduced, the ablation is carried out in a radiation mode, the condition that the electrode is exposed in the renal artery in radio frequency ablation is avoided, the conditions of damage to the renal artery, deviation of the ablation position and stenosis of the renal artery are avoided, and meanwhile, compared with ultrasonic ablation, the radiation antenna has lower treatment cost and use cost;
According to the invention, by arranging the choke coil unit, the electric field of the microwave ablation area can be restrained, the tailing ablation area existing in the ablation area in the prior art is reduced, the ablation area is made to be approximately a cylinder, the shape of target tissue can be adapted to the maximum extent, and the tailing ablation area is prevented from ablating non-target areas.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present invention is not limited to the specific embodiments disclosed below.
Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be included in at least one implementation of the invention. The appearances of the phrase "in one preferred embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Further, in describing the embodiments of the present invention in detail, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of description, and the schematic is only an example, which should not limit the scope of protection of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.
Referring to fig. 1,2, and 5 to 9, this embodiment provides a flexible microwave ablation catheter, which includes an outer catheter 100, a cooling tube 110, and a coaxial cable 120 sequentially disposed from outside to inside, the coaxial cable 120 including a coaxial core 121, a first dielectric layer 122 coaxially disposed around the coaxial core 121, and a coaxial outer conductor 123 coaxially disposed around the first dielectric layer 122, one end of the coaxial core 121 being provided with a radiation end, and further including:
The outer catheter 100 comprises a plurality of cage type supporting units, wherein the cage type supporting units are assembled inside the wall of the outer catheter 100, the cage type supporting units comprise a plurality of high-strength fiber filaments 101, the high-strength fiber filaments 101 are slidably connected into the wall of the outer catheter 100, all the high-strength fiber filaments 101 in the plurality of cage type supporting units are annularly arranged in the wall of the outer catheter 100 at equal angles, in the same cage type supporting unit, the included angles between two adjacent high-strength fiber filaments 101 are the same, a plurality of guide outlets are formed in the outer side of the outer catheter 100, the guide outlets are matched with the high-strength fiber filaments 101 one by one, the high-strength fiber filaments 101 in the same cage type supporting unit slide out of the wall of the outer catheter 100 to form a lantern-shaped structure, and the outer catheter 100 can keep a centered state in a blood vessel through the plurality of cage type supporting units.
Here, the device is used together with a control end and a refrigerant conveying device, the control end can control the outer guide tube 100 to move in the blood vessel, the refrigerant conveying device is used for conveying a refrigerant, a microwave input end, a water inlet pipe and a water outlet pipe are arranged in the control end, the microwave input end is connected with the coaxial cable 120, and the output end of the water inlet pipe and the refrigerant conveying device, the water inlet pipe and the cooling pipe 110, the water outlet pipe and the input end of the refrigerant conveying device and the water outlet pipe and the outer guide tube 100 are all connected with each other.
Specifically, a propulsion mechanism is further arranged in the control end, the propulsion mechanism is connected with the high-strength fiber yarn 101, and the propulsion mechanism can drive the high-strength fiber yarn 101 to move relative to the outer catheter 100, so that the cage type supporting unit is changed between an initial state and a working state.
It should be noted that, when the high-strength fiber yarn 101 is completely located inside the wall of the outer catheter 100, the cage-type supporting unit is in an initial state; when the high-strength fiber yarn 101 slides out of the inside of the wall of the outer catheter 100 to form a lantern-shaped structure, the lantern-shaped supporting unit is in an operating state.
In this embodiment, in the renal sympathetic nerve removal operation through the catheter, the outer catheter 100 is guided to the target position by the imaging device, the pushing mechanism inside the control end is driven to operate, the cage type supporting unit is driven to operate by the pushing mechanism, so that the high-strength fiber yarn 101 moves relative to the outer catheter 100, the high-strength fiber yarn 101 slides out of the outer catheter 100 from the guiding outlet to the outside of the outer catheter 100, and slides out of the high-strength fiber yarn 101 stroke lantern-shaped structure of the wall of the outer catheter 100, so that the cage type supporting unit is converted from an initial state to a working state, after the cage type supporting unit is contacted with the inner wall of a blood vessel, the outer catheter 100 is in an centered state inside the blood vessel by the cage type supporting unit, so that the radiation antenna on the coaxial inner core 121 is in a centered state inside the blood vessel, the situation that one side is completely ablated and the other side is not completely ablated in the ablation operation process is avoided, meanwhile, the lantern type cage type supporting unit can avoid the situation that the blood inside the renal artery is not smooth, and the acute thrombus of a patient is caused, and the safety risk is reduced.
In a specific embodiment, as shown in fig. 6, the number of cage-type supporting units is three, each cage-type supporting unit is composed of three high-strength fiber filaments 101, and the total of the three cage-type supporting units comprises nine high-strength fiber filaments 101, and at the position B-B, the schematic cross-sectional view is shown in fig. 7; at C-C, a schematic cross-sectional view is shown in FIG. 8; at D-D, a schematic cross-sectional view is shown in FIG. 9; of course, the number of the cage-type supporting units and the number of the high-strength fiber yarns 101 in each cage-type supporting unit can be adjusted according to specific use environments and use requirements, so long as the number of the cage-type supporting units is at least two, each cage-type supporting unit at least comprises three high-strength fiber yarns 101, and no limitation is made here.
Further, the pushing mechanism is an existing mature application, is widely applied to the technical field of ablation needles or ablation catheters, and can adjust the posture or the introduction depth of the ablation needles or the ablation catheters, and further description is omitted here.
In a preferred embodiment, referring again to fig. 1-4, a flexible microwave ablation catheter further comprises:
the support tube 124, the support tube 124 is fixed at one end of the inner part of the outer catheter 100, a plurality of support ribs are arranged in the support tube 124, one end of the cooling tube 110, which is close to the support tube 124, is fixedly connected, and the radiation end penetrates through the inner part of the support tube 124;
The plurality of metal columns 125 are assembled outside the radiation ends and are positioned in the support tube 124, the radiation ends and the plurality of metal columns 125 jointly form a radiation antenna, and the plurality of metal columns 125 are in one-to-one correspondence with the plurality of support ribs;
a choke unit 130, the choke unit 130 being mounted on the outer side of the coaxial outer conductor 123, the choke unit 130 being for confining an electric field of the microwave ablation zone;
wherein, during transcatheter renal sympathetic nerve removal, the cooperation of the support tube 124 and the plurality of metal posts 125 can keep the radiation antenna centered inside the outer catheter 100 and avoid the occurrence of curling phenomenon of the radiation antenna.
Further, after the refrigerant conveying device conveys the refrigerant to the inside of the cooling tube 110, the refrigerant flows to the inside of the outer conduit 100 sequentially through the water inlet tube, the cooling tube 110 and the supporting tube 124, flows to the water outlet tube through the gap between the supporting tube 124 and the outer conduit 100, and finally flows back to the inside of the refrigerant conveying device, wherein the refrigerant can be one of the following substances: pure water or normal saline is preferable as the refrigerant in this embodiment.
It should be noted that, the end of the outer catheter 100 near the supporting tube 124 is arc-shaped or semicircular, so as to avoid scratching the wall of the blood vessel when the outer catheter 100 moves inside the blood vessel, and the materials of the outer catheter 100 and the cooling tube 110 may be any of the following materials: PI, PTFE, PEEK or other polymer materials, preferably, in this embodiment, the outer tube 100 and the cooling tube 110 are made of PEEK.
In this embodiment, in the transrenal sympathetic nerve removal operation, the outer catheter 100 is guided to the target position by the imaging device, during the guiding process, the end of the outer catheter 100 away from the control end can bend along with the shape of the blood vessel for multiple times, the support tube 124 inside the outer catheter 100 can bend synchronously along with the outer catheter 100, the radiation antenna inside the outer catheter 100 is driven to bend synchronously by the support tube 124, simultaneously, the plurality of metal posts 125 and the support ribs arranged inside the support tube 124 can keep the radiation antenna in a central state all the time when the radiation antenna follows the outer catheter 100 to bend synchronously, simultaneously, the radiation antenna is limited by the cooperation of the plurality of metal posts 125, the occurrence of curling of the radiation antenna is avoided, microwaves are conveyed to the coaxial inner core 121 by the control end, and the microwaves are emitted by the radiation antenna to form a radiation area, the method has the advantages that polar molecules in tissues in a radiation area are rotated and vibrated to generate a thermal effect, the sympathetic nerves in the radiation area are inactivated in a heating mode, in the process, blood flowing in blood vessels can absorb heat of blood vessel walls to cool the blood vessel walls, the sympathetic nerves on the outer sides of the renal artery blood vessels are uniformly ablated around the blood vessels by 360 degrees through the scheme, so that the ablation effect and the ablation efficiency are improved, the phenomenon of repeated ablation is avoided, meanwhile, the sympathetic nerves are ablated in a radiation mode, the risk of damage to the renal artery caused by exposure of electrodes to the interior of the renal artery is avoided, the problem that the positions of ablation catheters are shifted due to the fact that current flows through human tissues to cause vascular or muscle spasm, the ablation positions shift and postoperative renal artery stenosis are avoided, and compared with an ultrasonic ablation technology, the method does not need to use a high-frequency ultrasonic transducer, high cost techniques such as high power ultrasound output, etc., reduce the cost of use and the cost of treatment for the patient.
In a preferred embodiment, the support tube 124 is made of any one of the following materials: ABS, PTFE, PI, PEEK or other polymeric materials, preferably, in this embodiment, the support tube 124 is preferably PEEK.
Furthermore, PEEK (polyether ether ketone) is a mature material in the prior art, is a high polymer formed by a repeating unit with a ketone bond and two ether bonds in a main chain structure, belongs to a special high polymer material, has high mechanical strength, high temperature resistance, impact resistance, flame retardance, acid and alkali resistance, hydrolysis resistance, wear resistance, fatigue resistance, irradiation resistance and good electrical property, and has a great deal of application in the aerospace field, the medical instrument field (serving as an artificial bone repair bone defect) and the industrial field, and is not further described herein.
In this embodiment, the stay tube 124 can follow the shape of blood vessel and take place to bend many times at the in-process that blood vessel inside moved, and the stay tube 124 of PEEK material has good compliance, can take place to bend many times along with blood vessel shape, and simultaneously, it still has good mechanical strength, can form the support to outer pipe 100 and radiation antenna, through the inside supporting rib that sets up of stay tube 124, can effectively avoid the radiation antenna to take place to curl the phenomenon after taking place to bend many times, can also keep centering state in outer pipe 100 inside.
In a preferred embodiment, the length of the metal posts 125 ranges from 1.5mm to 5mm, and the distance between two adjacent metal posts 125 ranges from 2mm to 8mm in the horizontal direction.
It should be noted that, the lengths of the plurality of metal columns 125 located inside the same supporting tube 124 may be different, the distances between two adjacent metal columns 125 may be different, and the lengths of the metal columns 125 and the distances between two adjacent metal columns 125 may be adaptively adjusted within the above-mentioned range according to the use requirements and the use environments.
In this embodiment, the longer the length of the metal post 125, the larger the minimum bending radius of the radiation antenna in the blood vessel, the larger the distance between two adjacent metal posts 125, the smaller the supporting and limiting effects of the metal posts 125 on the radiation antenna, by adjusting the length of the metal post 125 and the distance between two adjacent metal posts 125, the metal posts 125 can form good support for the radiation antenna after the radiation antenna follows the outer catheter 100 in the blood vessel for multiple times, so as to avoid the deflection of the radiation antenna relative to the outer catheter 100, and meanwhile, the smaller bending radius can be kept, so that the radiation antenna can be suitable for the position with smaller bending radius in the renal artery, and the applicability of the device is improved.
In a specific embodiment, when performing transcatheter renal sympathetic nerve removal, the number of metal posts 125 is 6, the length of the metal posts 125 is 3mm, the distance between two adjacent metal posts 125 is 3.5mm, the total length of the radiating antenna is 39mm, the effective length of the single radiating ablation zone is about 40mm, and of course, the number of metal posts 125, the length of the metal posts 125, and the distance between two adjacent metal posts 125 can be adjusted according to the size of the target ablation, the path of travel of the ablation catheter, and the minimum bend radius of the renal artery, without limitation herein.
Next, referring to fig. 2 again, the choke unit 130 includes a second dielectric layer 131, a conductive layer 132 and a metal ring 133, the second dielectric layer 131 is coaxially disposed on the outer side of the coaxial outer conductor 123, the conductive layer 132 is coaxially disposed on the outer side of the second dielectric layer 131, the metal ring 133 is assembled on the outer side of the support tube 124 and is located at one end of the second dielectric layer 131 away from the support tube 124, and the conductive layer 132 is electrically connected with the metal ring 133.
Further, the material of the second dielectric layer 131 is one of the following materials: ABS, PTFE, PI, PEEK or other polymer materials, the material of the metal ring 133 may be one of the following materials: copper, silver or other metals with good electrical conductivity.
In this embodiment, the choke unit 130 is configured to constrain an electric field in a microwave ablation area, so that the ablation area is approximately a "cylinder", and a "tailing" ablation area is avoided in the ablation area, so that the size of the ablation area can be maximally adapted to the shape of the target tissue, and the situation that the shape of the ablation area and the shape of the target tissue cannot be maximally adapted due to the existence of the "tailing" ablation area in the ablation area is avoided, and meanwhile, the ablation of a non-target area by the "tailing" ablation area can be avoided.
In a specific embodiment, referring to fig. 10 to 12, a numerical simulation software is used to perform modeling simulation experiment and electromagnetic radiation SAR distribution diagram observation, the vessel diameter is set to 6mm, the blood flow is set to 0.6L/min, the model is provided with an ablation catheter at the center of the vessel, the microwave input power is set to 60W, the working time is 300s, the simulation result is shown in fig. 10, the currently more commonly accepted cell damage temperature is 53 ℃, the instantaneous death temperature of the cell is 60 ℃, the isotherm results of 53 ℃ and 60 ℃ are listed in fig. 12, it can be seen from the simulation result that the ablation area at 53 ℃ is about 42mm x 12mm on one side, the ablation area at 60 ℃ is about 36mm x 8mm on one side, the ablation area is about 0.8mm apart from the vessel wall, this is sufficient to generate thermal injury to most renal nerves, and most renal nerves exist in the range of 1-6 mm in the lumen of the blood vessel while preserving the intima and tissue of blood vessels within about 0.5mm, and considering that the length of the ablation catheter may reach 1.5m or even longer in practical use, the maximum output power may reach 150W in practical use to cope with cable loss of 1.5m length, it can be seen from the above-mentioned experimental results of mode simulation that the choke unit 130 is provided, so that the electric field of the microwave ablation region can be restrained, the "tailing" ablation region existing in the ablation region in the prior art can be reduced, the ablation region becomes approximately "cylinder" and can be maximally adapted to the shape of the target tissue, and the "tailing" ablation region is prevented from ablating the non-target region.
Referring again to FIG. 2, the wall thickness of the second dielectric layer 131 is denoted as L1, the wall thickness of the metal ring 133 is denoted as L2, and L2 is equal to or greater than L1, in this embodiment, L2 > L1 is preferred.
In this embodiment, by the above arrangement, the conductive layer 132 can be easily established, and the phenomenon that the conductive layer 132 is broken or poorly contacted due to the step can be avoided.
In a preferred embodiment, the conductive layer 132 is made of any one of the following materials: conductive ink, conductive paste, silver paste and metal flakes.
In this embodiment, when the material of the conductive layer 132 is conductive ink, conductive adhesive or silver paste, the conductive ink, conductive adhesive or silver paste needs to be disposed on the outer side of the second dielectric layer 131 in a coating manner, after the conductive ink, conductive adhesive or silver paste is cured, the conductive layer 132 and the metal ring 133 can be electrically connected, and when the material of the metal ring 133 is a metal sheet, the conductive layer 132 is disposed on the outer side of the second dielectric layer 131 in a surrounding coating manner, and the metal ring 133 is connected with the conductive layer 132.
In a preferred embodiment, the length of conductive layer 132 is denoted as Lm,0.05λ0≤Lm≤0.2λ0, where λ0 represents the microwave wavelength in vacuum.
It should be noted that, the most commonly used frequencies in clinic for microwave ablation are 915MHz and 2450MHz, and more than 2450MHz, the wavelength λ0 of 915MHz is about 330mm, the wavelength λ0 of 2450MHz is about 122.5mm, and in this embodiment, the microwave frequency is preferably 2450MHz.
In a specific embodiment, when the frequency of the microwave is 2450MHz, the wavelength λ0 of the microwave is about 122.5mm, and the value of the length Lm of the conductive layer 132 is about 6mm to 25mm.
In a preferred embodiment, a protective film is disposed on the outer side of the choke unit 130, and the protective film is made of any one of the following materials: in the present embodiment, the material of the protective film is preferably PET, and the protective film is disposed outside the choke unit 130 by heat shrinkage.
In this embodiment, the protective film is provided, so that corrosion of the conductive layer 132 and the metal ring 133 can be prevented, and the service life can be prolonged.
The working principle of the invention is as follows:
In the renal sympathetic nerve removal operation of the catheter, the outer catheter 100 is guided to a target position through an imaging device, in the guiding process, one end of the outer catheter 100 away from the control end can bend for a plurality of times along with the shape of a blood vessel, a supporting tube 124 in the outer catheter 100 can bend synchronously along with the outer catheter 100, a radiation antenna in the outer catheter 100 is driven to bend synchronously through the supporting tube 124, meanwhile, the radiation antenna can always keep a central state in the outer catheter 100 when the radiation antenna follows the outer catheter 100 to bend synchronously through the cooperation of a plurality of metal columns 125, meanwhile, the radiation antenna is limited through the cooperation of the metal columns 125, the radiation antenna is prevented from curling, a propelling mechanism in the control end is driven to operate, a cage type supporting unit is driven to operate through the propelling mechanism, and the high-strength fiber yarn 101 moves relative to the outer catheter 100, the high-strength fiber yarn 101 slides out of the outer catheter 100 from the guide outlet, the high-strength fiber yarn 101 slides out of the tube wall of the outer catheter 100 to form a lantern-shaped structure, the cage-type supporting unit is further converted into a working state from an initial state, after the cage-type supporting unit is contacted with the inner wall of a blood vessel, the outer catheter 100 is in a centering state in the blood vessel through the cage-type supporting unit, meanwhile, the lantern-shaped cage-type supporting unit does not cause unsmooth blood flow, the radiation antenna on the coaxial inner core 121 is in a centering state in the blood vessel through the cooperation of the outer catheter 100 and the supporting tube 124, microwaves are conveyed to the coaxial inner core 121 through the control end, and the microwaves are emitted through the radiation antenna to form a radiation area, so that the polar molecular rotational vibration in the tissue in the radiation area generates a heat effect, nerves in the radiation area are inactivated through a heating mode, in the process, the flowing blood in the blood vessel can absorb the heat of the wall of the blood vessel, the wall of the blood vessel is cooled, the sympathetic nerves outside the blood vessel of the renal artery are uniformly ablated around the blood vessel by 360 degrees through the scheme, so that the ablation effect and the ablation efficiency are improved, the phenomenon of repeated ablation is avoided, meanwhile, the sympathetic nerves are ablated in a radiation mode, the problems of renal artery injury, vascular or muscle spasm, deviation of the ablation position and postoperative renal artery stenosis caused by exposure of the electrode to the interior of the renal artery are avoided, and compared with an ultrasonic ablation technology, the ultrasonic ablation device does not need high-cost technologies such as a high-frequency ultrasonic transducer, high-power ultrasonic output and the like, and the use cost and the treatment cost of patients are reduced.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention. Structures, devices and methods of operation not specifically described and illustrated herein, unless otherwise indicated and limited, are implemented according to conventional means in the art.