Aortic valve stent and method of using same

Abstract

The application discloses an aortic valve guide wire and a use method thereof, which comprises a head section, a transition section and a support section connected in sequence along an axial direction; the head section is composed of a polymer and further comprises a deformation capsule, at least one closed unit embedded in the head section, and an internal sealing electric field sensitive viscoelastic fluid; a mesh cable is arranged on the surface of the deformation capsule and extends to the transition section; the transition section and the support section are provided with a conductive film on the surface, and the conductive film is connected with the mesh cable and used for applying a non-uniform electric field to the deformation capsule to generate a regional viscosity difference and drive the head section to bend in a direction.The electric field sensitive viscoelastic fluid built in the head section generates a regional viscosity difference under the action of the non-uniform electric field, and the difference is converted into a directional bending moment through the synergistic effect of the mesh cable and the conductive film, so that the head of the guide wire can quickly respond to an external electric signal and accurately deflect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to an aortic valve guide wire and a use method thereof. BACKGROUND

[0002] The guide wire is also called as a guide steel wire or a guide line, and is one of main tools for a percutaneous puncture operation. The guide wire plays a guiding and supporting role for a catheter for instrument delivery, and the guide wire can establish a delivery track for an instrument to enter a human body, guide the instrument to enter a blood vessel or other cavity disease position, and the guide wire is a prerequisite for the instrument to reach the disease position smoothly.

[0003] The aortic valve guide wire is used to establish a valve delivery track in a aortic valve intervention operation (TAVAR), and plays an important supporting role in a valve delivery process. The percutaneously implantable aortic valve structure is complex, and a required delivery sheath tube has a large diameter, and in addition, a patient's aorta is hardened and twisted, so that when the artificial valve is pushed to the heart along the delivery sheath tube, the tension and resistance are very large, and the guide wire needs to be placed in the left ventricular cavity as a aortic valve pushing track to avoid damage to the aortic wall by the delivery device.

[0004] However, the aorta is twisted at multiple places, and the conventional guide wire needs to be manually twisted to select the advancing direction, the advancing process is slow, and there is obvious dragging and friction on the blood vessel wall.

[0005] Therefore, it is necessary to provide an aortic valve guide wire and a use method thereof to solve the above technical problems. SUMMARY

[0006] The present application overcomes the deficiencies of the prior art, and provides an aortic valve guide wire and a use method thereof.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows: an aortic valve guide wire, comprising a head section, a transition section and a support section connected in sequence along an axial direction, a core wire is arranged on the aortic valve guide wire, and the core wire penetrates through the transition section and the support section;

[0008] The head section is composed of a polymer, and further comprises:

[0009] A deformation capsule, at least one closed unit embedded in the interior of the head section, and an electric field sensitive viscoelastic fluid is enclosed in the interior;

[0010] A mesh cable is arranged on the surface of the deformation capsule and extends to the transition section;

[0011] The transition section and the support section are provided with a conductive film connected with the mesh cable for applying a non-uniform electric field to the deformation capsule to generate a regional viscosity difference to drive the head section to bend directionally.

[0012] In a preferred embodiment of the present application, the deformation capsule is arranged at one end close to the transition section and has a cylindrical structure.

[0013] In a preferred embodiment of the present application, the mesh cable is in a serpentine line on the surface of the deformation capsule and is uniformly distributed on the surface of the deformation capsule, and each group of serpentine lines of the mesh cable is designed as a double-stranded line.

[0014] In a preferred embodiment of the present application, at least two independent conductive networks composed of the mesh cable and the conductive film are arranged on the aortic valve guide wire to cooperate with the application of a non-uniform electric field.

[0015] In a preferred embodiment of the present application, the conductive film is an ACF film with a thickness of 30-50 μm.

[0016] In a preferred embodiment of the present application, the electric field sensitive viscoelastic fluid is a barium titanate based electrorheological system or a lithium tantalate based electrorheological system.

[0017] In a preferred embodiment of the present application, the core wire in the transition section has a tapered structure and gradually decreases in diameter as it approaches the head section; the transition section and the support section further comprise a polymer sheath arranged on the surface of the core wire.

[0018] The conductive film is arranged on the surface of the polymer sheath, and an insulating coating is arranged on the surface of the conductive film.

[0019] In a preferred embodiment of the present application, a plurality of narrow slits are arranged on the surface of the polymer sheath of the transition section, and the spacing of the narrow slits gradually decreases as they approach the head section.

[0020] A use method of an aortic valve guide wire, comprising the following steps:

[0021] S1, pushing the aortic valve guide wire until the head section reaches the bifurcation region;

[0022] S2, an external controller connects the conductive film at the tail of the support section and applies a current to provide a non-uniform electric field to the deformation capsule through the mesh cable;

[0023] S3, the non-uniform electric field causes the viscoelastic fluid to generate a regional viscosity difference, and the head section is deflected directionally under the driving of the bending moment to guide the aortic valve guide wire into the target branch path.

[0024] S4, the electric field is turned off, the viscosity of the deformation capsule returns to be uniform, the head section returns to be straight, and the aortic valve guide wire is continuously pushed.

[0025] In one preferred embodiment of the present application, in the S2, the external controller simultaneously connects at least two independent conductive networks composed of the mesh cable and the conductive film, and applies different voltages to the conductive films in different directions according to the bifurcation path, so as to form a non-uniform electric field on the deformation capsule.

[0026] The present application solves the defects in the background art and has the following beneficial effects:

[0027] (1) The present application provides an aortic valve guide wire, which belongs to a polymer sheath structure guide wire, mainly applied in transcatheter aortic valve replacement (TAVR), and the aortic root structure is complex, with a tortuous aortic arch and a severely calcified aortic valve annulus. The elastic modulus of the polymer sheath is lower than that of metal, which better fits the tortuous path of the aorta, reduces the pushing resistance, and through the built-in electric field sensitive viscoelastic fluid in the head section, regional viscosity difference is generated under the action of a non-uniform electric field, which is converted into a directional bending moment, so that the guide wire head can quickly respond to external electric signals and accurately deflect, and the guide wire can quickly and accurately pass through the tortuous path of the aorta.

[0028] (2) Compared with the traditional manual twisting guide wire, the aortic valve guide wire provided by the present application can accurately adapt to the complex path at the blood vessel bifurcation by real-time regulation of the bending direction through the electric field, avoid hard friction between the guide wire and the blood vessel wall, and reduce the risk of blood vessel injury.

[0029] (3) The deformation capsule prepared based on the barium titanate-based electrorheological system and the lithium tantalate-based electrorheological system in the present application forms a chain structure along the direction of the electric field when an external non-uniform electric field of 0-90 V / mm is applied, the viscosity of the dispersed phase particles is rapidly increased by 6-8 times, and the initial state can be restored when the external electric field is removed or under a uniform electric field. Under a non-uniform electric field, the viscosity of the viscoelastic fluid on one side is significantly higher than that on the other side, forming a regional viscosity difference; due to the flexibility of the polymer main body of the head section, the rigidity of the region with high viscosity is enhanced, while the region with low viscosity remains flexible, thereby generating a bending moment at the interface between the two, driving the head section to deflect to the side with low viscosity, i.e. the target branch direction. That is, the head section can realize directional bending of 15-30° under a non-uniform electric field, and the bending angle is positively correlated with the electric field intensity difference.

[0030] (4) The barium titanate-based electrorheological system in the shape-changing capsule uses core-shell structure particles with a particle size of 50-100 nm of nano barium titanate particles as a core layer, a thickness of 5-10 nm of polyaniline (PANI) conductive polymer as a shell layer as a dispersed phase, fluorosilicone oil as a continuous phase, and the mass ratio of the dispersed phase to the continuous phase is 1.1-2.68:1. The barium titanate-based electrorheological system is a low viscosity fluid without an electric field, with a viscosity of about 0.2-0.3 Pa·s, and when an external electric field is applied (0-90 V / mm), the dispersed phase particles form a chain structure along the direction of the electric field, and the viscosity quickly rises to 1.2-2 Pa·s, with a viscosity change of about 6 times, and the initial state can be restored after the external electric field is removed, wherein the PANI as the conductive shell layer enhances the effective dipole moment of the dispersed phase particles through the interface polarization effect, and strong polarization can be generated under a low electric field. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 is the aortic valve guide wire straight state structure diagram of preferred embodiments 1 and 2 of the present application;

[0033] Figure 2 is the aortic valve guide wire bent state structure diagram of preferred embodiments 1 and 2 of the present application;

[0034] Figure 3 is the aortic valve guide wire use method flow chart of preferred embodiment 3 of the present application;

[0035] In the figure: 1, head section; 2, transition section; 3, support section; 4, core wire; 5, shape-changing capsule; 6, narrow slit. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0038] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0039] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] The head section of the existing guide wire is designed in two types: spring ring sheath structure and polymer sheath structure. Among them, the spring ring sheath structure is tightly wound by spiral-shaped filaments made of stainless steel or nickel-titanium alloy, and the diameter of the metal wire is mostly 0.05-0.2mm. The rigid structure of the metal spring ring can provide strong radial support force, and is mainly used for peripheral vascular intervention requiring strong support force. The polymer sheath structure is coated on the surface of the core wire by polyurethane, polytetrafluoroethylene or polyether block amide. The polymer material is soft and smooth in surface, and has small friction when contacting with blood vessels, which significantly reduces the risk of blood vessel abrasion, intimal injury and the like, and is mainly used in brain artery thrombectomy, stent implantation or blood vessel tortuosity and the like.

[0041] The present application provides an aortic valve guide wire, which belongs to the guide wire of polymer sheath structure, and is mainly applied in transcatheter aortic valve replacement (TAVR). The aortic root structure is complex, with tortuous aortic arch and severely calcified aortic valve ring. The elastic modulus of the polymer sheath is lower than that of the metal, which better fits the tortuous path of the aorta, reduces the pushing resistance, and through the regional viscosity difference generated by the electric field sensitive viscoelastic fluid built-in in the head section under the action of non-uniform electric field, converts into directional bending moment, so that the guide wire head can quickly respond to external electric signal and accurately deflect, and can quickly and accurately pass through the tortuous path of the aorta.

[0042] Example 1:

[0043] Figure 1A schematic diagram of an aortic valve guide wire in the embodiment is shown. The aortic valve guide wire comprises a head section 1, a transition section 2 and a support section 3 connected in sequence along the axial direction, and a core wire 4 is arranged on the aortic valve guide wire and penetrates through the transition section 2 and the support section 3. The total length of the head section is 20-30 mm, the total length of the transition section is 55-65 mm, and the total length of the support section is 1000-1100 mm.

[0044] The core wire 4 is a stainless steel wire or a stainless steel and nickel-titanium alloy wire, and the core wire 4 is subjected to quenching treatment to increase the support and elasticity of the core wire 4. The diameter of the tip of the core wire 4 is 0.3 mm, and the diameter of the core wire 4 in the support section 3 is 0.5 mm.

[0045] The head section 1 is composed of a polymer and further comprises a deformation capsule 5 and a mesh cable. The main body of the head section 1 is composed of a biocompatible polymer, preferably polyurethane (PU) or polytetrafluoroethylene (PTFE). Polyurethane has excellent flexibility and fatigue resistance, can adapt to complex bending paths in the blood vessel, and its surface smoothness can reduce the friction resistance with the blood vessel wall; polytetrafluoroethylene has extremely low surface energy, which can further reduce the drag friction when the guide wire is pushed, and its chemical stability can avoid reaction with blood components, reducing the risk of thrombosis.

[0046] The molding process of the polymer main body adopts injection molding, and the axial length 25-30 mm and the outer diameter of the head section 1 (smoothly transitioned with the transition section 2, the outer diameter range is 0.8-1.2 mm) are controlled by the mold to ensure the connection strength of the transition section 2 and the coaxiality of the whole guide wire.

[0047] The deformation capsule 5 is configured as at least one closed unit embedded in the head section 1, and an electric field sensitive viscoelastic fluid, i.e. electrorheological fluid, is sealed inside. The electric field sensitive viscoelastic fluid is a barium titanate-based electrorheological system, which is specifically as follows:

[0048] The core-shell structure particles with particle size of 50-100 nm of nano-sized barium titanate (BaTiO3) particles as core layer and thickness of 5-10 nm of polyaniline (PANI) conductive polymer as shell layer are used as the dispersed phase, fluorosilicone oil is used as the continuous phase, and the mass ratio of the dispersed phase to the continuous phase is 1.1-2.68:1, preferably 1.5-2.0:1, to balance the viscosity response and dispersion stability. The viscosity of the fluorosilicone oil is 50-300 cSt, and the density is 1.3-1.5 g / cm 3The barium titanate-based electrorheological fluid is a low viscosity fluid without an electric field, with a viscosity of about 0.2-0.3 Pa·s. When an external electric field is applied (0-90 V / mm), the dispersed phase particles form a chain structure along the direction of the electric field, and the viscosity quickly rises to 1.2-2 Pa·s, with a viscosity change of about 6 times. The initial state can be restored after the external electric field is removed. The PANI acts as a conductive shell to enhance the effective dipole moment of the dispersed phase particles through the interface polarization effect, and strong polarization can be generated at a low electric field.

[0049] Further, to improve the compatibility of the dispersed phase particles and the silicone oil and prevent agglomeration, a small amount of surfactant is added to the barium titanate-based electrorheological fluid, including one or more of stearic acid, oleic acid, Span 80, Tween 80, and sodium dodecyl benzene sulfonate.

[0050] Under the action of an external electric field, the dispersed phase particles generate induced dipoles due to dielectric polarization, and the particles arrange along the electric field direction through dipole-dipole interaction, forming a chain or column structure, as follows:

[0051] Uniform electric field: The particle chains are uniformly distributed, and the overall viscosity of the fluid increases.

[0052] Non-uniform electric field: Different voltages are applied to the deformation capsule of the head section of the guide wire through an independent conductive network (such as 90 V on the left and 0 V on the right), forming an electric field intensity gradient (Eleft=90 V / mm, Eright=0 V / mm).

[0053] Under a non-uniform electric field, the particle chain structure density in different regions is different due to the regional difference in electric field intensity: the dispersed phase particles in the high electric field region have a larger dipole moment, the chain structure is more dense, and more inter-chain interactions need to be broken during fluid shearing, resulting in high viscosity; while the dispersed phase particles in the low electric field region have a sparse particle chain, resulting in low viscosity.

[0054] The deformation capsule of the aortic valve guide wire head section has a cylindrical structure, with the high electric field region and the low electric field region on the two sides. When the guide wire is advanced, the vessel wall exerts a shearing action on the head section, resulting in a difference in shear stress between the two sides of the fluid, which drives the head section to deflect towards the low electric field region, because the high viscosity side has higher rigidity and the low viscosity side is more easily deformed.

[0055] The deformation capsule 5 of this embodiment is arranged near one end of the transition section 2. The deformation capsule 5 is close to the transition section 2, which can shorten the distance between the deformation capsule 5 and the conductive film of the transition section 2, reduce the extension length of the mesh cable, thereby reducing the cable resistance loss and improving the electric field application efficiency; at the same time, the action point of the bending moment is closer to the "flexibility-rigidity" transition area of the guide wire (i.e. the connection position of the head section 1 and the transition section 2), which can more effectively drive the overall deflection of the head section 1. The deformation capsule 5 is coaxial with the guide wire, and the contact area between the surface of the deformation capsule 5 and the mesh cable is maximized, ensuring uniform distribution of the electric field.

[0056] The diameter ratio of the deformation capsule 5 to the head section 1 is 0.6-0.8:1. If the diameter ratio is less than 0.6:1, the volume of the deformation capsule 5 is too small, the viscosity change of the viscoelastic fluid is insufficient to drive the bending of the head section 1, and the guidance cannot be effectively directed. If the diameter ratio is greater than 0.8:1, the deformation capsule 5 occupies too large a volume of the head section 1, resulting in the thickness of the polymer body of the head section 1 being too thin, and there is a risk of rupture due to bending of the head section 1, vessel compression or friction.

[0057] The axial length of the deformation capsule 5 is 1 / 2-2 / 3 of the length of the head section 1, so as to ensure that the electric field acting region covers the main guiding part of the head section 1.

[0058] The mesh cable in the embodiment provides an electric field input path for the deformation capsule 5. The mesh cable is arranged in a serpentine line on the surface of the deformation capsule 5, the total length of the serpentine section is consistent with the length of the deformation capsule, and covers the axial length of the deformation capsule. The serpentine structure can buffer the stress when the guide wire is bent, and avoid cable breakage; each group of serpentine lines is designed with double-strand wires (two silver-plated copper wires with a diameter of 0.05-0.1 mm are arranged in parallel), one of which is positive and the other is negative, forming a differential signal pair, and the double-strand differential signal reduces external electromagnetic interference such as radio frequency equipment in the operating room.

[0059] It should be noted that the surface of the mesh cable is coated with a 5-10 μm biocompatible insulating layer to prevent direct contact between the mesh cable and the polymer body or blood, which can cause short circuiting. Preferably, the biocompatible insulating layer is a polyaryletheretherketone (PAEK) coating.

[0060] The transition section 2 and the support section 3 are provided with a conductive film (ACF) on the surface, specifically an anisotropic conductive film with a thickness of 30-50 μm, which is connected with the mesh cable. Specifically, the surface of the transition section 2 and the support section 3 is provided with 2-4 independent ACF strips, which are evenly distributed circumferentially around the guide wire, such as 2 strips corresponding to the left and right directions, and 4 strips corresponding to the up, down, left and right directions. The end of the mesh cable extends to the transition section 2, each ACF strip is connected with a group of mesh cables to form an independent conductive path, which is used to apply a non-uniform electric field to the deformation capsule 5 to generate a regional viscosity difference and drive the head section 1 to bend directionally.

[0061] The external controller applies different voltages through different ACF strips, and the voltage range is 0-90 V. The current is transmitted to the corresponding region on the surface of the deformation capsule through the mesh cable, forming an electric field intensity gradient.

[0062] Figure 2A bending schematic diagram of the aortic valve guide wire head section 1 of the present embodiment is shown. The main bending process of the head section 1 is as follows: the external controller applies voltage through the conductive film at the tail of the support section 3, the current is transmitted to the corresponding mesh cable through the conductive film of the transition section 2, and a non-uniform electric field is formed on the surface of the deformation capsule 5. At this time, the viscosity of one side of the viscoelastic fluid is significantly higher than that of the other side, forming a regional viscosity difference; due to the flexibility of the polymer body of the head section 1, the rigidity of the region with higher viscosity is enhanced, while the region with lower viscosity remains flexible, thereby generating a bending moment at the interface between the two, driving the head section 1 to deflect to the side with lower viscosity, i.e. the target branch direction.

[0063] The core wire 4 in the transition section 2 has a tapered structure, with the diameter gradually decreasing as it approaches the head section 1. The diameter of the core wire 4 in the support section 3 is 0.5-0.8 mm, and the diameter of the core wire 4 near the end of the transition section 2 close to the head section 1 is 0.2-0.4 mm, with a taper of 1:10-1:20. The transition section 2 and the support section 3 also include a polymer sheath arranged on the surface of the core wire 4, with a thickness of 0.1-0.2 mm and a material consistent with that of the head section 1. The conductive film is arranged on the surface of the polymer sheath, and the surface of the conductive film is provided with an insulating coating.

[0064] The diameter of the core wire 4 gradually decreases along the transition section 2 to the head section 1, causing the rigidity of the guide wire to be distributed in a gradient, thereby avoiding stress concentration caused by sudden changes in rigidity. At the same time, the tapered structure can reduce the mass difference of the connection area between the transition section 2 and the head section 1, and reduce the inertial impact when the guide wire is pushed forward. The polymer sheath wraps the core wire 4, which can fill the micro defects on the surface of the core wire 4, reduce the roughness of the outer surface of the transition section 2 and the support section 3, and reduce the friction with the blood vessel wall.

[0065] A plurality of narrow slits 6 are formed on the surface of the polymer sheath of the transition section 2, with a slit width of 0.05-0.1 mm and a slit depth of 0.05-0.1 mm. The spacing between the narrow slits 6 gradually decreases as they approach the head section 1, for example, the spacing between the narrow slits 6 on the side of the support section 3 is 2 mm, and the spacing on the side of the head section 1 is 0.5 mm. The narrow slits 6 reduce the circumferential continuity of the polymer sheath, making the flexibility of the transition section 2 increase along the axial direction, and cooperating with the rigidity gradient of the tapered core wire 4 to ensure smooth transition of the guide wire from the support section 3 to the head section 1, avoiding blood vessel damage caused by excessive rigidity in a local area. When the guide wire is bent in the blood vessel, the narrow slits 6 can act as "stress relief grooves" to absorb the tensile or compressive strain of the sheath, avoiding cracking of the sheath due to excessive deformation; the gradually changing spacing design makes the strain distribution more uniform, further improving the fatigue resistance of the polymer sheath.

[0066] The tapering core wire 4 of the transition section 2 is designed to gradually change its diameter from 0.5-0.8 mm of the support section 3 to 0.2-0.4 mm of the head section 1, with a taper ratio of 1:10-1:20, forming a smooth mechanical transition zone. This allows the guide wire to maintain sufficient rigidity of the support section 3 while retaining sufficient flexibility of the transition section 2 to smoothly pass through curved blood vessels, solving the problem of rigid transition of the guide wire three-section structure, and reducing the risk of blood vessel perforation compared to the stress concentration phenomenon caused by the traditional guide wire rigid mutation.

[0067] Embodiment 2:

[0068] The present embodiment provides an aortic valve guide wire. The aortic valve guide wire comprises a head section 1, a transition section 2 and a support section 3 connected in sequence along the axial direction, and a core wire 4 arranged on the aortic valve guide wire and penetrating through the transition section 2 and the support section 3. The total length of the head section is 25-30 mm, the total length of the transition section is 55-65 mm, and the total length of the support section is 1000-1100 mm.

[0069] The core wire 4 is a stainless steel wire or a stainless steel and nickel-titanium alloy wire, and the core wire 4 is subjected to quenching treatment to increase the support and elasticity of the core wire 4. The diameter of the tip of the core wire 4 is 0.3 mm, and the diameter of the core wire 4 in the support section 3 is 0.5 mm.

[0070] The head section 1 is composed of a polymer and further comprises a deformation capsule 5 and a mesh cable. The main body of the head section 1 is composed of a biocompatible polymer, preferably polyurethane (PU) or polytetrafluoroethylene (PTFE). Polyurethane has excellent flexibility and fatigue resistance, can adapt to complex curved paths in blood vessels, and its surface smoothness can reduce the friction resistance with the blood vessel wall; polytetrafluoroethylene has extremely low surface energy, which can further reduce the drag friction when the guide wire is pushed, and its chemical stability can avoid reaction with blood components, reducing the risk of thrombosis.

[0071] The molding process of the polymer main body adopts injection molding, which controls the axial length 25-30 mm and the outer diameter (smoothly transitions with the transition section 2, with an outer diameter range of 0.8-1.2 mm) of the head section 1 through a mold, ensuring the connection strength of the transition section 2 and the coaxiality of the overall guide wire.

[0072] The deformation capsule 5 is configured as at least one closed unit embedded inside the head section 1, which encloses an electric field sensitive viscoelastic fluid, i.e. electrorheological fluid. The electric field sensitive viscoelastic fluid is a lithium tantalate-based electrorheological system, which is specifically as follows:

[0073] The core-shell structure particle has a lithium tantalate (LiTaO3) nanoparticle with a particle size of 30-100 nm as a core layer and a polyaniline (PANI) conductive polymer with a thickness of 5-10 nm as a shell layer as a dispersed phase, a fluorosilicone oil as a continuous phase, and a mass ratio of the dispersed phase to the continuous phase is 1.37-2.58:1, preferably 1.8-2.2:1, which balances high viscosity variation and fluidity. The viscosity of the fluorosilicone oil is 50-300 cSt, and the density is 1.3-1.5 g / cm 3 The lithium tantalate-based electrorheological system is a low-viscosity fluid without an electric field, with a viscosity of about 0.28-0.4 Pa·s, and when an external electric field is applied (0-90 V / mm), the dispersed phase particles form a chain structure along the direction of the electric field, and the viscosity quickly rises to 2.2-3.1 Pa·s, with a viscosity change of about 8 times, and the initial state can be restored after the external electric field is removed. Among them, PANI as a conductive shell layer enhances the effective dipole moment of the dispersed phase particles through the interface polarization effect, and strong polarization can be generated at a low electric field. Compared with the barium titanate-based electrorheological system, the lithium tantalate-based electrorheological system has a higher dielectric constant and a larger viscosity change under an electric field, and is suitable for scenarios that require stronger bending moments.

[0074] Further, to improve the compatibility of the dispersed phase particles and the silicone oil and prevent agglomeration, a small amount of surfactant is added to the lithium tantalate-based electrorheological system, including one or more of γ-aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, lithium stearate, and polyethylene glycol.

[0075] Under the action of an external electric field, the dispersed phase particles generate induced dipoles due to dielectric polarization, and the particles arrange along the direction of the electric field through dipole-dipole interaction, forming a chain or column structure, as follows:

[0076] Uniform electric field: The particle chains are uniformly distributed, and the overall viscosity of the fluid increases;

[0077] Non-uniform electric field: In the deformation capsule of the wire head section, different voltages are applied through independent conductive networks (such as 90V on the left and 0V on the right), forming an electric field intensity gradient (Eleft=90V / mm, Eright=0V / mm).

[0078] Under a non-uniform electric field, the particle chain structure density in different regions is different due to the regional difference in electric field intensity: the dispersed phase particles in the high electric field region have a larger dipole moment and a denser chain structure, and more inter-chain interactions need to be broken when the fluid is sheared, resulting in a high viscosity; while the dispersed phase particles in the low electric field region have a sparse particle chain structure, resulting in a low viscosity.

[0079] The deformation capsule of the aortic valve guide wire head section is cylindrical, and the two sides correspond to the high electric field area and the low electric field area respectively. When the guide wire advances, the blood vessel wall exerts a shearing action on the head section, and the difference in shear stress of the fluid on both sides causes the difference in shear force on both sides of the deformation capsule, which drives the head section to deflect to the low electric field area. Because the high viscosity side is more rigid and the low viscosity side is more deformable.

[0080] The deformation capsule 5 of the embodiment is arranged near one end of the transition section 2. The deformation capsule 5 is close to the transition section 2, which can shorten the distance between the conductive film of the transition section 2 and the deformation capsule 5, reduce the extension length of the mesh cable, thereby reducing the cable resistance loss and improving the electric field application efficiency; at the same time, the action point of the bending moment is closer to the "flexible-rigid" transition area of the guide wire (i.e. the connection position of the head section 1 and the transition section 2), which can more effectively drive the overall deflection of the head section 1. The deformation capsule 5 is coaxial with the guide wire, and the contact area between the surface of the deformation capsule 5 and the mesh cable is maximized, ensuring uniform distribution of the electric field.

[0081] The diameter ratio of the deformation capsule 5 to the head section 1 is 0.6-0.8:1. If the diameter ratio is <0.6:1, the volume of the deformation capsule 5 is too small, and the driving force of the viscosity change of the viscoelastic fluid for the bending of the head section 1 is insufficient, which cannot effectively guide; if the diameter ratio is >0.8:1, the deformation capsule 5 occupies too large a volume of the head section 1, resulting in too thin thickness of the polymer body of the head section 1, which may have a risk of rupture due to bending of the head section 1, blood vessel extrusion or friction.

[0082] The axial length of the deformation capsule 5 is 1 / 2-2 / 3 of the length of the head section 1, so as to ensure that the electric field action area covers the main guiding part of the head section 1.

[0083] The mesh cable in the embodiment provides an electric field input path for the deformation capsule 5. The mesh cable is arranged in a serpentine line on the surface of the deformation capsule 5, and the total length of the serpentine section is consistent with the length of the deformation capsule, covering the axial length of the deformation capsule. The serpentine structure can buffer the stress when the guide wire bends, avoiding cable breakage; each group of serpentine lines is designed with double-strand wires (two silver-plated copper wires with a diameter of 0.05-0.1 mm are arranged in parallel), one of which is positive and the other is negative, forming a differential signal pair, which reduces external electromagnetic interference through double-strand differential signals, such as radio frequency equipment in the operating room.

[0084] It should be noted that the surface of the mesh cable is coated with a 5-10 μm biocompatible insulating layer to prevent direct contact between the mesh cable and the polymer body or blood, which may cause short circuit, wherein the biocompatible insulating layer is preferably a parylene coating.

[0085] The transition section 2 and the support section 3 are provided with a conductive film (ACF) on the surface, specifically an anisotropic conductive film with a thickness of 30-50 μm, which is connected with the mesh cable. Specifically, the transition section 2 and the support section 3 are provided with 2-4 independent ACF strips on the surface, which are evenly distributed along the circumference of the guide wire, such as 2 strips corresponding to the left and right directions, and 4 strips corresponding to the up, down, left and right directions. The mesh cable extends to the transition section 2, and each ACF strip is connected with a group of mesh cables to form an independent conductive path, which is used to apply a non-uniform electric field to the deformation capsule 5 to generate a regional viscosity difference, and drive the head section 1 to bend in a certain direction.

[0086] The external controller applies different voltages through different ACF strips, and the voltage range is 0-90 V. The current is transmitted to the corresponding area on the surface of the deformation capsule through the mesh cable to form an electric field intensity gradient.

[0087] The active bending process of the head section 1 is as follows: the external controller applies a voltage through the conductive film at the tail of the support section 3, and the current is transmitted to the corresponding mesh cable through the conductive film of the transition section 2 to form a non-uniform electric field on the surface of the deformation capsule 5. At this time, the viscosity of the left side viscoelastic fluid is significantly higher than that of the right side, forming a regional viscosity difference. Since the polymer body of the head section 1 has a certain flexibility, the rigidity of the area with higher viscosity is enhanced, while the area with lower viscosity remains flexible, thereby generating a bending moment at the interface between the two areas, driving the head section 1 to deflect to the side with lower viscosity, i.e. the target branch direction.

[0088] The core wire 4 in the transition section 2 has a tapered structure, and the diameter gradually decreases as it approaches the head section 1. The diameter of the core wire 4 in the support section 3 is 0.5-0.8 mm, and the diameter of the core wire 4 at the end of the transition section 2 close to the head section 1 is 0.2-0.4 mm, with a taper of 1:10-1:20. The transition section 2 and the support section 3 further comprise a polymer sheath arranged on the surface of the core wire 4, with a thickness of 0.1-0.2 mm and a material consistent with the polymer material of the head section 1. The conductive film is arranged on the surface of the polymer sheath, and the surface of the conductive film is provided with an insulating coating.

[0089] The diameter of the core wire 4 gradually decreases along the transition section 2 to the head section 1, so that the rigidity of the guide wire is distributed in a gradient manner, avoiding stress concentration caused by sudden changes in rigidity. At the same time, the tapered structure can reduce the mass difference of the connection area between the transition section 2 and the head section 1, and reduce the inertial impact when the guide wire is pushed forward. The polymer sheath wraps the core wire 4, which can fill the micro defects on the surface of the core wire 4, reduce the roughness of the outer surface of the transition section 2 and the support section 3, and reduce the friction with the blood vessel wall.

[0090] The polymer sheath surface on the transition section 2 is provided with a plurality of narrow slits 6, the slit width is 0.05-0.1 mm, the slit depth is 0.05-0.1 mm, the narrow slits 6 gradually become smaller with the interval close to the head section 1, for example, the narrow slit 6 interval on the support section 3 side is 2 mm, and the interval on the head section 1 side is 0.5 mm. The narrow slits 6 reduce the circumferential continuity of the polymer sheath, increase the flexibility of the transition section 2 along the axial direction, and form a gradient with the rigidity of the tapered core wire 4, so as to ensure the smooth transition of the guide wire from the support section 3 to the head section 1, and avoid the damage of the blood vessel caused by local excessive rigidity. When the guide wire is bent in the blood vessel, the narrow slits 6 can act as a "stress release groove" to absorb the tensile or compressive strain of the sheath, so as to avoid the cracking of the sheath due to excessive deformation; the interval gradually changes, so that the strain distribution is more uniform, and the fatigue resistance of the polymer sheath is further improved.

[0091] The tapered core wire 4 adopted by the transition section 2 is designed in a gradient, the diameter gradually changes from 0.5-0.8 mm of the support section 3 to 0.2-0.4 mm of the head section 1, and the taper ratio is 1:10-1:20, so as to form a smooth mechanical transition zone. The guide wire can keep enough flexibility of the transition section 2 while keeping enough rigidity of the support section 3, and smoothly pass through the curved blood vessel, so as to solve the rigidity transition problem of the guide wire with a three-section structure, and reduce the risk of blood vessel perforation compared with the stress concentration phenomenon caused by the rigidity mutation of the traditional guide wire. In particular, it is worth mentioning that the narrow slits 6 arranged in steps on the surface of the polymer sheath form a controllable strain release channel, when the guide wire passes through the curved blood vessel, the interval of the narrow slits 6 decreases from 2 mm of the support section 3 to 0.5 mm of the head section 1, so as to effectively disperse the circumferential strain and prolong the fatigue life of the sheath.

[0092] The aortic valve guide wire provided by the embodiments 1 and 2 of the present application can accurately adapt to the complex path at the bifurcation of the blood vessel by real-time regulation of the bending direction through the electric field compared with the traditional manual twisting guide wire, avoids the hard friction between the guide wire and the blood vessel wall, and reduces the risk of blood vessel injury.

[0093] Embodiment 3:

[0094] Figure 3 A flow chart of a use method of the aortic valve guide wire in the embodiment is shown. The use method of the aortic valve guide wire comprises the following steps:

[0095] In step S1, a matched guide wire pusher (such as a spring handle type pusher, the surface of which is covered with a medical silicone anti-slip layer) is used to fix the guide wire by clamping the tail of the support section 3, so as to avoid slipping during pushing, and the aortic valve guide wire is pushed until the head section 1 reaches the bifurcation area, and the position of the guide wire is monitored in real time through intraoperative medical imaging assistance (such as DSA digital subtraction angiography or intravascular ultrasound IVUS).

[0096] Step S2, the external controller connects the conductive film at the tail of the support section 3, and according to the desired deflection angle, applies current to the conductive film on the non-target side, and provides a non-uniform electric field to the deformation capsule 5 through the mesh cable, such as: 90V on the non-target side and 0V on the target side.

[0097] Step S3, the non-uniform electric field causes regional viscosity difference in the deformation capsule 5, the viscosity on the non-target side is much higher than that on the target side, and the head section 1 is deflected to the target side under the driving of the bending moment, guiding the aortic valve guide wire into the target branch path. Specifically:

[0098] The electric field sensitive viscoelastic fluid filled in the deformation capsule 5 generates regional viscosity difference Δη under the non-uniform electric field:

[0099] The high electric field area (such as the left side) has a viscosity η1=1.2-2Pa·s (electric field intensity 90V / mm);

[0100] The low electric field area (such as the right side) has a viscosity η2=0.2-0.3Pa·s (electric field intensity 0V / mm);

[0101] The viscosity difference causes the shear modulus difference ΔG (shear modulus G=η×shear rate γ, γ=10-100s ～1 ) on both sides of the deformation capsule 5, thereby generating a bending moment M: , wherein D is the diameter of the deformation capsule 5, and L is the length of the deformation capsule 5.

[0102] Step S4, turn off the electric field or change it to a uniform electric field, the viscosity of the electric field sensitive viscoelastic fluid in the deformation capsule 5 restores to be uniform, the head section 1 restores to be linear, and the aortic valve guide wire continues to be pushed forward.

[0103] In step S2, the external controller simultaneously connects at least two independent conductive networks composed of mesh cables and conductive films, and applies different voltages to the conductive films in different directions according to the bifurcation path, to form a non-uniform electric field on the deformation capsule 5.

[0104] The number of independent conductive networks is preferably 2-4, which are uniformly distributed along the circumference of the guide wire, such as 2 corresponding to left and right directions, and 4 corresponding to up, down, left and right. Adjust the voltage difference ΔV by measuring the branch angle θ of the bifurcation path.

[0105] The use method of the aortic valve guide wire provided in the embodiment, by means of the dynamic response characteristics of the electric field sensitive viscoelastic fluid, the head section is realized directional bending by the external controller exerting non-uniform electric field on the deformation capsule 5. Compared with the manual twisting mode of the traditional guide wire relying on the experience of the operator, the bending direction can be real-time regulated by the electric field, the complex path of the bifurcation of the blood vessel can be accurately adapted, the hard friction between the guide wire and the blood vessel wall is avoided, and the risk of blood vessel injury is reduced. When the electric field is removed or becomes uniform, the electric field sensitive viscoelastic fluid quickly restores the uniform viscosity, and the head section 1 automatically rebounds to the linear form. The reversible phase change characteristics completely abandon the operation process of repeatedly manually straightening the traditional guide wire, so that the guide wire can still smoothly pass through the subsequent blood vessel section after being bent and guided.

[0106] Embodiment 4:

[0107] The embodiment discloses a preparation method of an aortic valve guide wire, and the aortic valve guide wire is prepared according to the embodiment 1, and the preparation method comprises the following steps:

[0108] In step M1, a stainless steel wire or a stainless steel and nickel-titanium alloy wire is selected as a core wire material, and is processed to a diameter of 0.6 mm through a cold drawing process, the cold drawing is performed by using a conical grinding tool, the diameter of the core wire is gradually changed from 0.6 mm of the support section to 0.3 mm of the head end of the transition section, and then the core wire is subjected to quenching treatment, so that the support property and the elasticity of the core wire are improved.

[0109] In step M2, an electric field sensitive viscoelastic fluid is prepared, the electric field sensitive viscoelastic fluid is injected into the polymer closed unit, and the deformation capsule is obtained. Specifically,

[0110] In step M21, 10 g of BaTiO3 nanoparticles with a particle size of 80 nm are taken, are dispersed in 1 L of deionized water, 1 g of aniline monomer is added, ultrasonic dispersion is performed for 30 min, 50 mL of 0.1 mol / L ammonium persulfate solution is added dropwise, stirring is performed at 0-5 DEG C for 2 h, a PANI shell layer with a thickness of 8 nm is formed, centrifugal washing (ethanol / water=1:1) is performed for 3 times, and 60 DEG C vacuum drying is performed for 24 h, so that the BaTiO3@PANI core-shell particles are obtained as a dispersed phase.

[0111] In step M22, 150 g of the dispersed phase is mixed with 100 g of fluorosilicone oil, 1 g of stearic acid is added, stirring is performed at 2000 rpm for 2 h, vacuum defoaming is performed for 30 min, and the electric field sensitive viscoelastic fluid is obtained.

[0112] Step M23, inject the prepared electric field sensitive viscoelastic fluid into the preformed polymer closed unit with a cavity diameter of 0.7 mm and an axial length of 15 mm, then seal the two ends of the cavity with medical epoxy glue, and cure at room temperature for 24 h to obtain a deformation capsule. In the preforming of the polymer closed unit, two groups of mesh cables are symmetrically attached to the outside, and each group of mesh cables occupies ½ of the surface of the polymer closed unit.

[0113] Step M3, coat the polyurethane on the surface of the core wire by an extruder, and the coated diameter is consistent with the diameter of the deformation capsule. After the first coating, 2 ACF strips are attached to the surface of the core wire, each with a thickness of 40 μm and a width of ¼ of the circumferential length of the first coated core wire, and symmetrically distributed on both sides of the first coated core wire.

[0114] Step M4, weld the ends of the two groups of mesh cables to the corresponding ACF strips by conductive glue, and coat the surface of the mesh cable with a layer of Parylene C coating with a thickness of 8 μm by vapor deposition.

[0115] Step M5, coat the polyurethane on the surface of the deformation capsule and the first coated core wire by an extruder, and the outer diameter is 1.0 mm. Laser processing narrow slots on the surface of the polymer sheath of the transition section, with a slot width of 0.05 mm and a slot depth of 0.05 mm. The narrow slot spacing on the support section is 2 mm, and the spacing on the head section is 0.5 mm, to obtain an aortic valve guide wire.

[0116] Example 5:

[0117] The present embodiment discloses a preparation method of an aortic valve guide wire, which is prepared as in Example 2, comprising the following steps:

[0118] Step N1, select stainless steel wire or stainless steel and nickel-titanium alloy wire as the core wire material, and process it to a diameter of 0.6 mm by cold drawing process. The cold drawing is performed by a tapered grinding tool, and the diameter of the core wire is gradually changed from 0.6 mm at the support section to 0.3 mm at the head end of the transition section, and then the core wire is quenched to improve the support and elasticity of the core wire.

[0119] Step N2, prepare an electric field sensitive viscoelastic fluid, and inject the electric field sensitive viscoelastic fluid into the polymer closed unit to obtain a deformation capsule. Specifically:

[0120] Step N21, take 10 g of 50 nm LiTaO3 nanoparticles, disperse them in 1 L of deionized water, add 1 g of aniline monomer, ultrasonically disperse for 30 min, then add 50 mL of 0.1 mol / L ammonium persulfate solution dropwise, stir at 0-5℃ for 2 h to form a PANI shell layer with a thickness of 8 nm; centrifugal washing (ethanol / water=1:1) for 3 times, and vacuum drying at 60℃ for 24 h to obtain LiTaO3@PANI core-shell particles as the dispersed phase.

[0121] Step N22, 180 g of the dispersed phase was mixed with 100 g of fluorosilicone oil, 1.5 g of γ-aminopropyltriethoxysilane was added, stirred at 2000 rpm for 2 h, and vacuum degassed for 30 min to obtain an electric field sensitive viscoelastic fluid.

[0122] Step N23, the prepared electric field sensitive viscoelastic fluid was injected into a preformed polymer closed unit with a cavity diameter of 0.7 mm and an axial length of 15 mm, and then the cavity ends were sealed with medical epoxy glue, and cured at room temperature for 24 h to obtain a deformation capsule. During the preforming of the polymer closed unit, two groups of mesh cables were symmetrically attached to the outside, and each group of mesh cables occupied ½ of the surface of the polymer closed unit.

[0123] Step N3, polyurethane was coated on the surface of the core wire by an extruder, and the coated diameter was consistent with the diameter of the deformation capsule. Two ACF strips were attached to the surface of the once-coated core wire, each with a thickness of 40 μm and a width of ¼ of the circumferential length of the once-coated core wire, and symmetrically distributed on both sides of the once-coated core wire.

[0124] Step N4, the ends of the two groups of mesh cables were welded to the corresponding ACF strips by conductive glue, and a layer of paclitaxel C coating was applied on the surface of the mesh cable by vapor deposition, with a thickness of 8 μm.

[0125] Step N5, polyurethane was coated on the surface of the deformation capsule and the once-coated core wire by an extruder, with an outer diameter of 1.0 mm. Narrow slits were laser processed on the surface of the polymer sheath of the transition section, with a slit width of 0.05 mm and a slit depth of 0.05 mm. The narrow slits on the support section had a spacing of 2 mm, and the narrow slits on the head section had a spacing of 0.5 mm, to obtain an aortic valve guide wire.

[0126] The aortic valve guide wire samples prepared in Examples 4 and 5 were subjected to bending experiments.

[0127] The guide wires prepared in Examples 4 and 5 were connected to external controllers, respectively, and the bending angles of the head sections under different electric field intensities were tested, respectively. The electric field included uniform electric field and non-uniform electric field: left side 0 V and right side 90 V, left side 0 V and right side 70 V, left side 0 V and right side 50 V, left side 50 V and right side 50 V.

[0128] The guide wire was fixed on the test platform, the head section was suspended, and the electric field was applied in the order of left side 0 V, right side 90 V→70 V→50 V→left side 50 V, right side 50 V. After each electric field was stable for 5 s, the deflection angle of the head section relative to the initial direction was measured by DSA. Finally, the electric field was removed, and the time for the head section to return to a straight line was recorded. The experimental results are shown in Table 1 below.

[0129] Table 1. Guide wire bending angle data table

[0130]

[0131] From the above Table 1, it can be seen that the bending angle of the directional 15-30° can be realized under the non-uniform electric field of Example 4 and Example 5, and the bending angle is positively correlated with the electric field intensity difference, and there is no directional deflection under the uniform electric field; the lithium tantalate-based electrorheological system is more suitable for the clinical scene requiring strong bending moment due to the better performance of the electrorheological fluid and the larger bending angle.

[0132] The above is based on the ideal embodiment of the application, and through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the application. The technical scope of the application is not limited to the content of the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. An aortic valve guide wire comprising a head section, a transition section and a support section connected in sequence along an axial direction, a core wire is arranged on the aortic valve guide wire, characterized in that: The core wire runs through the transition section and the support section; The head section is made of polymer and further comprises: A deformation capsule, at least one closed unit embedded inside the head section, enclosing an electric field sensitive viscoelastic fluid; A mesh cable, arranged on the surface of the deformation capsule and extending to the transition section; The transition section and the support section are provided with a conductive film on the surface, which is connected with the mesh cable and used to apply a non-uniform electric field to the deformation capsule to generate a regional viscosity difference and drive the head section to bend in a certain direction.

2. An aortic valve guide wire according to claim 1, characterized in that: The deformation capsule is arranged at one end close to the transition section and has a cylindrical structure.

3. An aortic valve guide wire according to claim 1, characterized in that: The mesh cable is in a serpentine line on the surface of the deformation capsule and is uniformly distributed on the surface of the deformation capsule, and each group of serpentine lines of the mesh cable is designed as a double-stranded line.

4. The aortic valve guide wire of claim 1, wherein: At least two independent conductive networks composed of the mesh cable and the conductive film are arranged on the aortic valve guide wire to cooperate with the application of a non-uniform electric field.

5. The aortic valve guide wire of claim 1, wherein: The conductive film is an ACF film with a thickness of 30-50 μm.

6. An aortic valve guide wire according to claim 1, characterized in that: The electric field sensitive viscoelastic fluid is a barium titanate-based electrorheological system or a lithium tantalate-based electrorheological system.

7. The aortic valve guide wire of claim 1, wherein: The core wire in the transition section has a tapered structure and gradually decreases in diameter as it approaches the head section; the transition section and the support section further comprise: a polymer sheath arranged on the surface of the core wire; and the conductive film is arranged on the surface of the polymer sheath.

8. An aortic valve guide wire according to claim 7, characterized in that: A plurality of narrow slits are arranged on the surface of the polymer sheath of the transition section, and the intervals of the narrow slits gradually decrease as they approach the head section.

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