Magnetic resonance compatible implantable electrode wire with shunt head end structure and medical equipment

Abstract

The invention discloses a magnetic resonance compatible implantable electrode wire with a shunt head end structure and medical equipment. An electrode head section comprises a spiral electrode electrically connected with an inner wire body and a ring electrode electrically connected with an outer wire body; the spiral electrode and the ring electrode transmit an electric signal sent by the implanted medical device to a targeted treatment part to be electrically stimulated; the spiral electrode comprises a spiral structure; the spiral structure is a multi-turn equidistant spiral structure, and under the action of a high-frequency energy field, the spiral structure can serve as a series inductor to generate large impedance so as to reduce induction current flowing to the spiral electrode and human tissue, and therefore electrode heating is reduced. The structure of the electrode tip section is improved, and the problems that electromagnetic field energy is coupled, eddy current and induction current are formed, induction heating is generated, and even wrong electric pulse signals are transmitted to a human body on the implantable medical device, so that adverse effects are generated on the safety of a patient are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical electrical wire connectors, and in particular to a magnetic resonance compatible implantable electrode wire with a shunt head structure and a medical device. Background Art

[0002] Magnetic resonance imaging (MRI) is a widely used and increasingly popular medical imaging technique. The demand for MRI examinations among patients with implantable medical devices (IMDs), particularly elderly patients, is also rapidly increasing. Compared to other medical imaging techniques such as CT, MRI offers several advantages, including: 1. It is safer and does not deliver high doses of radiation. 2. Multiple scans are performed without causing radiation damage to the human body. 3. Its soft tissue density resolution is significantly higher than that of CT. 4. It can directly present three-dimensional and cross-sectional images, providing richer and more comprehensive diagnostic information.

[0003] Currently, the electrode leads for medical devices such as pacemakers are mainly divided into active and passive electrode leads. The passive electrode tip has a barbed structure that can be directly hooked onto the myocardial trabeculae. Over time, the electrode tip is wrapped by the myocardium and gradually stabilizes. The active electrode tip, on the other hand, has a spiral structure that telescopes into the myocardium and is fixed in the atrium or ventricle.

[0004] An implantable lead is a medical lead that connects one end to a pacemaker, defibrillator, or other electrical stimulation device and the other end directly to the area of the body that requires electrical stimulation, such as the heart or brain. The primary function of an implantable lead is to transmit tiny electrical pulses from the device to the desired structure and to transmit the body's electrical activity back to the device.

[0005] Magnetic resonance imaging (MRI) technology works through the coordinated cooperation of three magnetic fields, including a high-intensity uniform static magnetic field B0, with common intensities of 1.5T and 3T; a gradient magnetic field G, which can be set to any direction and cooperates with the static magnetic field B0 to encode body spatial information and image specific body parts; and an RF radio frequency field B1 for exciting proton nuclear resonance, which performs high-frequency time-varying switching at the Larmor frequency. In MRI with a static magnetic field B0 of 1.5T and 3T, its frequencies are 64MHz and 128MHz, respectively.

[0006] Implantable products must meet the above-mentioned MRI compatibility requirements. Due to the high-frequency and strong magnetic field working characteristics of MRI, MRI testing has long been an absolute forbidden area for patients undergoing electrical stimulator implantation surgery (typically pacemakers, defibrillators, deep brain stimulators, etc.). The most important reason is the mutual interference between the MRI comprehensive field and ferromagnetic materials and / or conductive objects. The most important hidden danger is the induced heating of the implanted product. The MRI field has a high-frequency energy field, including the rapidly switching gradient field G and RF radio frequency field B1, which will couple electromagnetic field energy to the implanted medical device, forming eddy currents and induced currents, causing induced heating, and may transmit erroneous electrical pulse signals to the human body, which will have an adverse effect on the patient's safety.

[0007] Therefore, the induced heating caused by the aforementioned eddy currents and induced currents is a technical problem that urgently needs to be addressed in this field. In particular, thin, conductive electrode wires behave as antennas in high-frequency energy fields, exhibiting a stronger ability to couple high-frequency field energy. This generates strong induced currents, much of which are converted into heat at the electrode tip / myocardial tissue interface. This can increase the electrical stimulation threshold, induce arrhythmias, and cause perforation, among other serious injuries. Furthermore, the wires can emit pulse voltages at unwanted times and locations, potentially leading to induced stimulation disorders. Summary of the Invention

[0008] The main purpose of the present invention is to provide a magnetic resonance-compatible implantable electrode lead with a shunt head structure, aiming to solve the problem of coupling electromagnetic field energy on implantable medical devices, forming eddy currents and induced currents, causing induced heating, and even transmitting erroneous electrical pulse signals to the human body, which has an adverse impact on patient safety.

[0009] Specifically, in an MRI environment, the slender structure of the electrode wire can couple with the high-frequency energy field, and the current induced within it can flow through the spiral electrode to the tissue, causing an increase in the electrical stimulation threshold, inducing arrhythmias and perforation, and other serious injuries, which is undesirable. Therefore, the present invention aims to achieve: using an electrode wire with a shunt function to shunt the induced current in the high-frequency energy field, thereby weakening the induced current flowing to the interface between the spiral electrode and tissue, reducing heating of the surrounding tissue, and preventing the electrode wire from transmitting pulse voltage at unnecessary times and locations, which may cause stimulation abnormalities.

[0010] To achieve the above objectives, the present invention provides an MRI-compatible implantable electrode lead with a shunt head structure, the electrode lead comprising:

[0011] A conductor main body section has a first end and a second end opposite to each other, the conductor main body section including an outer insulating tube and an outer conductor body, an inner insulating tube and an inner conductor body sequentially arranged in the outer insulating tube;

[0012] an electrode head section, provided at a first end of the lead body section; and a connector section, provided at a second end of the lead body section and connected to a medical device via a connector;

[0013] In an MRI scanning environment, the electrode wire is affected by the high-frequency energy field, which includes the changing gradient magnetic field G and the RF high-frequency pulse B1. The high-frequency energy field couples energy within the slender electrode wire, generating an induced electric field e and an induced current I along the length of the wire. The electrode wire is a conductor, and its length may be a multiple of the wavelength λ0 of the high-frequency energy field, resulting in an enhanced coupling effect and a large internal induced current I. The electrode wire contacts the human tissue through the spiral electrode to form a loop, and the induced current I flows into the human tissue through the spiral electrode. However, the contact area between the spiral electrode and the human tissue is small, resulting in a large current density at the interface between the electrode tip and the tissue, which causes a serious temperature rise in the spiral electrode, causing serious damage such as changes in the electrical stimulation threshold and tissue perforation. It may also cause the electrode wire to emit erroneous pulses at unnecessary times and locations, inducing stimulation abnormalities. Therefore, a large induced current I flowing into the spiral electrode is unacceptable.

[0014] To address the above-mentioned issues, the electrode head segment includes: a spiral electrode electrically connected to the inner conductor, and a ring electrode electrically connected to the outer conductor; the spiral electrode is used to be fixed to the patient's targeted treatment site, and the ring electrode is used to be immersed in human body fluids. The spiral electrode and the ring electrode transmit electrical signals emitted by the implanted medical device to the targeted treatment site to be electrically stimulated;

[0015] The spiral electrode comprises a spiral structure; the spiral structure is a spiral structure with multiple turns of equal distance. Under the action of a high-frequency energy field, the spiral structure can act as a series inductor to generate a large impedance, thereby reducing the induced current flowing to the spiral electrode and human tissue, thereby reducing electrode heating;

[0016] The inductance calculation formula of the spiral structure is:

[0017]

[0018] Wherein, μ0 is the vacuum permeability constant, μ0=4∏×10 -7 , N is the number of spiral turns, A is the cross-sectional area of the spiral electrode wire, and l is the length of the spiral structure; when the number of turns of the spiral structure increases, the approximate inductance L of the spiral electrode increases, and the series impedance increases, thereby reducing the induced current.

[0019] Optionally, the spiral electrode further comprises: a spiral electrode tip; during the implantation process, the spiral electrode tip is rotated and inserted into human tissue at the targeted treatment location;

[0020] The end of the inner wire body is nested and fixed at the distal outer position of the electrode core shaft away from the spiral electrode tip, and is fixed to the rear developing ring; the proximal position of the electrode core shaft close to the spiral electrode tip is connected to the front developing ring; and the front developing ring is connected to the spiral electrode;

[0021] The inner conductor body is driven to rotate in the inner insulating tube, so as to drive the spiral electrode accommodated in the electrode sleeve to move in a driven manner.

[0022] Optionally, a transmission tooth is provided in the electrode sleeve; the transmission tooth is transmission-connected to the spiral electrode, and converts the rotational motion of the spiral electrode into a telescopic motion along the axial direction of the spiral electrode.

[0023] Optionally, the inner conductor body is welded, crimped or clamped to the post-development ring to achieve electrical connection; and / or, the inner conductor body is welded, crimped or clamped to the electrode core shaft to achieve electrical connection.

[0024] Optionally, the number of spiral turns is 5 to 15 turns; and / or the length of the spiral structure is 5 mm to 10 mm.

[0025] Optionally, a protruding structure is arranged at a circumferential position of the spiral structure, and an end position of the protruding structure has a shunt contact for reducing current density; and / or,

[0026] Optionally, the protrusion structure may be in the shape of a cone, a polygon or a dot, etc.; the protrusion structure may be oriented toward or away from the spiral tip; and / or,

[0027] Optionally, the protruding structures on the spiral electrode are evenly and symmetrically arranged on the spiral structure in the circumferential direction; and / or,

[0028] Optionally, there is at least one protruding structure on the spiral electrode, and there is at least one shunt contact on the spiral electrode.

[0029] Optionally, the protrusion structure is a micro-protrusion with a protrusion height of 0.02-0.2 mm, and the area of the shunt contact is 0.01-0.1 mm. 2 ;

[0030] Under the influence of the high-frequency energy field, an induced current I is generated within the electrode wire, which accumulates at the tip, resulting in a high current density. This induced current I flows through the spiral electrode, where it accumulates at the tip and flows into the human tissue. The small contact area of the spiral electrode tip causes a high current density at the interface between the electrode tip and the tissue, leading to a significant temperature rise at the electrode tip in the tissue. The shunt contact increases the contact area between the spiral electrode and the tissue, dispersing the current accumulation at the spiral electrode tip, thereby reducing the current density J at the interface between the electrode tip and the tissue, and thus reducing heating of the electrode in the tissue.

[0031] The relationship between the current density J and the number of shunt contacts is:

[0032] Where I is the induced current, n is the number of shunt contacts, and A is the area of a single shunt contact. The more shunt contacts there are, the larger the area, and the smaller the current density J at each contact.

[0033] The heat generation calculation formula of the induced current I is: Q = I 2 R∝J 2

[0034] Where I is the induced current, R is the conductor resistance, and J 2 is the current density; the heat generation Q is proportional to the current density J. The greater the number and area of the shunt contacts, the more dispersed the induced current I is, and the smaller the current density J at a single contact is. This reduces the heat generation at the spiral electrode tip and the shunt contacts, evenly dissipating tissue heat and lowering localized heating temperatures.

[0035] Optionally, the electrode core shaft is made of a conductive material and has paramagnetic or diamagnetic properties and low magnetic susceptibility to meet the compatibility requirements of magnetic resonance imaging technology;

[0036] The electrode core shaft comprises: titanium and / or titanium alloy and / or platinum alloy and / or non-magnetic nickel-cobalt-chromium alloy and / or conductive polymer material.

[0037] Optionally, the electrode lead also includes:

[0038] The limiter induction current shunting structure comprises: the electrode sleeve 80, the electrode core shaft, and a conductive limiter;

[0039] The conductive stopper has an inner contact hole for the electrode core shaft to pass through and to be in electrical contact with the conductive stopper, so that the conductive stopper is electrically connected to the electrode wire;

[0040] The conductive limiter is provided with an outer contact surface and a forming surface at a circumferential position; the outer contact surface is in contact with the inner surface of the electrode sleeve; a sharp edge structure is formed on the forming surface, and the end point of the sharp edge forms a diversion tip;

[0041] Under the high-frequency energy field, an induced electric field e is induced inside the electrode wire.

[0042] The distribution formula of the induced electric field e is:

[0043]

[0044] Where r is the conductor curvature radius, and e is the induced electric field; the induced electric field e is inversely proportional to the curvature radius r. The curvature radius r at the shunt tip and the edge of the forming surface is extremely small, resulting in a tip effect at the shunt tip, which enhances the electric field intensity at the shunt tip and causes heating at the tip. The induced electric field e concentrates at the shunt tip and the edge of the forming surface, changing the overall distribution of the induced electric field e. This disperses and reduces the induced electric field intensity at the spiral electrode tip, lowering the induced current distributed in human tissue near the spiral electrode, thereby reducing heating of human tissue near the spiral electrode and minimizing thermal damage to human tissue during MRI scanning.

[0045] Optionally, the fixing step of the electrode sleeve and the end of the electrode insulating member facing the spiral electrode tip form a fixed space, and the fixed space is used to accommodate and position the conductive limiting member;

[0046] The outer contact surface of the conductive limiter is in contact with the inner cavity wall of the dielectric section of the electrode sleeve, and the outer surface of the dielectric section contacts human body fluids.

[0047] The conductive limiter and the electrode core shaft constitute the first pole of the equivalent capacitor C1, and the human body fluid is the second pole of the equivalent capacitor C1; at least a part of the dielectric segment is an intermediate dielectric material.

[0048] Unlike spiral electrodes that contact human tissue, the conductive limiter is isolated from human body fluids by a dielectric segment. There is a temperature difference between the conductive limiter and the human body fluids, and heat is effectively dissipated through heat transfer with the human body fluids, thereby reducing the heat generation of the electrode and preventing heat from being transferred to the tissue.

[0049] Optionally, an insulating seal is further provided between any two of the conductive limiters, and the insulating seal fits tightly against the conductive limiters to squeeze the insulating seal against the inner cavity wall of the electrode sleeve to form a sealing structure.

[0050] Optionally, the conductive limiter is located near the tip of the spiral electrode and is connected to a fixed step on the electrode sleeve for abutment and limitation; the conductive limiter is located away from the tip of the spiral electrode and is connected to an electrode insulating member for abutment and limitation.

[0051] Optionally, at least two of the conductive limiters in any group are respectively provided corresponding to the front developing ring and the rear developing ring at both sides of the length direction of the electrode core axis;

[0052] When the spiral electrode drives the electrode core shaft to extend and retract, the developing ring abuts against the conductive limiting member to limit the extension and retraction distance of the electrode core shaft; and the position of the spiral electrode is located according to the developing distance between the conductive limiting member and the developing ring.

[0053] Optionally, the spiral electrode, the conductive limiter, the front developing ring and the rear developing ring are made of conductive materials to meet the requirements of magnetic resonance imaging technology and development effect under X-ray irradiation;

[0054] The spiral electrode, the conductive limiter, the front developing ring and the rear developing ring are made of biocompatible developing materials with paramagnetic or diamagnetic properties and low magnetic susceptibility, including platinum iridium and / or platinum alloy and / or tantalum.

[0055] Optionally, the inner diameter of the inner contact hole of the conductive limiting member is smaller than the outer diameters of the front developing ring and the rear developing ring, so as to limit the developing ring; and / or,

[0056] The inner diameter of the inner contact hole of the conductive limiting member is approximately equal to the axial diameter of the electrode core shaft to ensure that the two are in electrical contact.

[0057] Optionally, the outer conductor body is nested on the outer conductor body support section at a position away from the spiral structure;

[0058] The outer conductor body has a cavity therein, and the inner insulating tube passes through the cavity to ensure that the inner conductor body and the outer conductor body are insulated from each other.

[0059] Optionally, the electrode insulating member is fixedly connected to the inner hole of the ring electrode on a side away from the spiral electrode tip; the inner insulating tube extends into the inner hole of the electrode insulating member on a side away from the spiral electrode tip and is fixed to the electrode insulating member to form insulation between the ring electrode and the outer wire body and the internal conductor of the electrode wire.

[0060] Optionally, the outer insulating tube passes through the outside of the outer wire body and is fixedly connected to the outer wall step of the ring electrode; the outer wall surface of the electrode insulating part is fixed to the dielectric section of the electrode sleeve on the side close to the spiral electrode tip; and a drug plug is fixed to the end of the electrode sleeve facing the spiral electrode tip.

[0061] Optionally, the electrode insulating member is bonded and fixed to the ring electrode; and / or the inner insulating tube is bonded and fixed to the electrode insulating member; and / or the outer insulating tube is bonded and fixed to the ring electrode; and / or the electrode insulating member is bonded and fixed to the dielectric segment; and / or the electrode sleeve is bonded and fixed to the drug plug;

[0062] The bonding and fixing method is to inject a biocompatible polymer adhesive for bonding. The polymer adhesive includes: biocompatible silicone adhesive and polyurethane adhesive.

[0063] Optionally, the conductive limiter is a columnar structure; the forming surface is a groove formed on the outer peripheral wall of the conductive limiter, and the diverter tip is formed at the connection position between the forming surface and the outer contact surface; or,

[0064] The conductive limiter is an elliptical structure; the diversion tip is formed at a circumferential position of the outer peripheral wall of the conductive limiter, and the outer contact surface is a section formed on the outer peripheral wall of the conductive limiter;

[0065] The conductive limiter has multiple shunt tips; under the high-frequency energy field, the concentration of the induced electric field e will cause the tip to heat up, making the induced heating area more dispersed, reducing the hot spot generated by each tip, and thus reducing the heat generation at the tip position of the spiral electrode.

[0066] Optionally, the forming surface of the conductive limiter may also be: polygonal, C-shaped or multi-angled; the forming surface has an angle less than or equal to 180°; and / or,

[0067] There is at least one shaped surface on the conductive limiter, and at least two diversion tips on the conductive limiter; and / or,

[0068] The number of the conductive limiters is at least two; a plurality of the conductive limiters can enhance the concentration of the induced electric field and enhance the weakening effect of the induced electric field at the tip of the spiral electrode; and / or,

[0069] The conductive limiting member is located on a side of the spiral electrode away from human tissue to prevent the conductive limiting member that diverts heat from contacting the tissue and causing secondary damage.

[0070] Optionally, the side wall of the end face of the conductive limiter of the columnar structure is further provided with a beveled surface for enhancing the electric field focusing capability of the shunt tip; the beveled surface is 0.05 mm to 1 mm.

[0071] Optionally, the electrode core shaft and / or the front developing ring and / or the rear developing ring and / or the ring electrode has a shunt tip for generating a tip effect.

[0072] Optionally, the conductive limiter and the electrode core shaft constitute a first pole of an equivalent capacitor C1, and human body fluids constitute a second pole of the equivalent capacitor C1;

[0073] The electrode lead is fixed to the patient's targeted treatment site via a spiral electrode. When the electrode lead is in normal working condition, the stimulation pulse emitted by the IMD is transmitted through the inner lead body to the spiral electrode, enters the human tissue, and completes the electrical stimulation. The stimulation pulse is then conducted to the ring electrode via the human body fluids, and then returns to the IMD via the outer lead body to form a loop.

[0074] Among them, the stimulation pulses emitted by the IMD are in low-frequency or DC form, and the equivalent capacitor C1 is in an open-circuit state; the electrode sleeve made of insulating material realizes insulation between the conductive limiter and human body fluids; the pulses transmitted by the inner wire body are transmitted to the spiral electrode through the electrode core shaft and the conductive limiter, and the electric pulses are transmitted to the human tissue, and only a negligible amount or no stimulation pulses are diverted.

[0075] Optional, such as Figure 9a As shown, the conductive limiter and the electrode core shaft constitute the first pole of the equivalent capacitor C1, and the human body fluid is the second pole of the equivalent capacitor C1;

[0076] The electrode wire is fixed to the patient's targeted treatment site via a spiral electrode. When the electrode wire is in an MRI scanning environment, an induced current is generated in the electrode wire under a high-frequency energy field, and capacitive coupling occurs between the conductive limiter and the human body fluid. The impedance of the equivalent capacitor C1 is at its lowest state. When the induced current I on the IMD and the electrode is transmitted to the conductive limiter via the electrode core shaft, the induced current I1 is transmitted along a path with lower impedance into the human body fluid surrounding the electrode sleeve, and the induced current I2 is transmitted into the human tissue via the spiral electrode, and then the current returns to the IMD via the human tissue and the human body fluid. The induced current I1 is greater than the induced current I2.

[0077] The thickness of the dielectric section, the size and number of the conductive limiters are adjusted to adjust the capacitance value of the equivalent capacitor C1, thereby obtaining the ability to shunt the induced current under a wide-spectrum high-frequency energy field.

[0078] Therefore, the induced current shunting structure of the limiter greatly reduces the induced current flowing to the spiral electrode, reducing the heat generated at the electrode tip and the tissue interface. The shunted induced current flows through the human body fluid to generate Joule heat, and the specific heat capacity of the human body fluid is large, and the temperature rise of the body fluid caused by Joule heat is small, which can avoid damage to the human body fluid and human tissue. At the same time, the special shape of the conductive limiter can gather the induced electric field e under the high-frequency energy field, which can enhance the shunting ability of the induced current under high frequency. By adjusting the value of the wall thickness of the dielectric segment, the size and number of the conductive limiters, the capacitance value of the equivalent capacitor C1 can be adjusted, thereby obtaining a satisfactory ability to shunt the induced current under the high-frequency energy field.

[0079] Among them, the wall thickness of the dielectric section is relatively thin, so as to reduce the inter-electrode distance of the equivalent capacitor C1, increase the capacitance value of the equivalent capacitor C1, and enhance the ability to shunt induced current under high-frequency energy field; at the same time, enhance the heat transfer effect between the conductive limiter and human body fluids.

[0080] Optionally, the electrode sleeve is made of a biocompatible insulating material, including: polyurethane, PEEK, polyimide, PTFE; and / or,

[0081] The wall thickness of the dielectric segment is 0.05 mm to 0.5 mm; and / or,

[0082] There are at least two conductive limiters, and the plurality of conductive limiters are spliced into an integrated structure to increase the area of the external contact surface, thereby increasing the first pole area of the equivalent capacitor C1, increasing the capacitance value of the equivalent capacitor C1, and enhancing the shunting effect; at the same time, the external contact surface is increased, the heat transfer area is increased, and the heat dissipation effect is enhanced. And / or,

[0083] The thickness of each conductive limiter is 0.2mm to 1mm, and the area of the outer contact surface is 2mm. 2 Up to 10mm 2 and / or,

[0084] The conductive limiting member is tightly connected to the inner cavity hole of the dielectric segment, and the diameter of the conductive limiting member is 1.5 mm to 2.5 mm.

[0085] Optional, such as Figure 9b As shown, the conductive limiter and the electrode core shaft constitute the first pole of the equivalent capacitor C1, and the human body fluid is the second pole of the equivalent capacitor C1;

[0086] The IMD is connected to the electrode circuit of the electrode wire, and the electrode circuit includes: a series resistor, a series impedance, a series inductor, and a parallel capacitor; the human tissue and the human body fluid form a resistance R, the inner wire body forms a series resistor R1, the outer wire body forms a series resistor R2, the resistance of the series conductor inside the electrode head segment is a series resistor R3, and the spiral electrode forms an equivalent series inductor L1 under the high-frequency energy field;

[0087] The electrode wire is fixed to the patient's targeted treatment site through a spiral electrode. When the electrode wire is in normal working state, Figure 7 As shown, electrical pulses are transmitted to the target tissue via the spiral electrode, then transmitted to the ring electrode via human tissue and body fluids, and then returned to the IMD to form a loop. The stimulation pulses emitted by the IMD are low-frequency or DC, and the equivalent capacitor C1 is in an open-circuit state. The spiral structure behaves like a conductor at low frequencies, and does not weaken the electrical pulse signal strength.

[0088] The electrode wire is fixed to the patient's targeted treatment site through a spiral electrode. When the electrode wire is in an MRI scanning environment, an induced current I is induced in the electrode circuit. The induced current I passes through the series resistor R1 representing the internal wire body resistance and the series resistor R2 representing the resistance of the electrode core shaft and the wire limiter. Since the frequency of the high-frequency energy field is extremely high and the impedance of the equivalent capacitor C1 is extremely small, the equivalent capacitor C1 is in a short-circuit state. The induced current I1 in the induced current I flows through the wire limiter represented by the series resistor R2 and passes through the equivalent capacitor C1 to the ground and flows to the human body fluid. The induced current I2 is transmitted through the spiral electrode to the resistor R formed by the human tissue. The series inductor L1 equivalently formed by the spiral electrode has a large impedance, which further weakens the magnitude of the induced current I2 and increases the induced current I1 of the human body fluid. When I2 flows through the resistor R represented by the human tissue, Joule heat is generated, causing the tissue to heat up. Although induced current I2 still flows into the human tissue, it is reduced by the shunt and the series inductor L1. As a result, despite the small contact area between the spiral electrode tip and the human tissue, the current density at the interface between the spiral electrode tip and the tissue is low, keeping the temperature rise at the human tissue within an acceptable range. In this case, induced current I1 is greater than induced current I2.

[0089] A medical device, comprising:

[0090] A machine body having a connection interface; and

[0091] An electrode wire, wherein the connector of the electrode wire is inserted into the connection interface.

[0092] In general, the electrode wire of the present invention is designed to shunt the induced current generated under the high-frequency energy field to the body fluid, and will not affect the transmission of the stimulation pulse during normal operation. The electrode wire of the present invention adopts one or more of the above methods to disperse the induced electric field e and shunt the induced current structure, so that the electrode presents a normal path under the working electric pulse, and only a very small amount of the working electric pulse signal is shunted, ensuring the normal progress of the treatment. During MRI scanning, the above structure can disperse the induced electric field e, weaken the self-heating of the spiral electrode, and at the same time, the structure presents a low impedance that is close to a short circuit, which can shunt most of the induced current to the body fluid and related components, weaken the induced current flowing to the spiral electrode, reduce thermal damage to the tissue, and at the same time gather the heating points in the body fluids and related components of the human body where the temperature rise is small, so the overall heat generation is small and away from the tissue, thereby ensuring the safety of the electrode wire during MRI scanning.

[0093] Preferably, in the above scheme, the stimulation pulse current diverted during normal operation accounts for less than about 3% of the total stimulation current. In addition, during MRI scanning, the induced current diverted to structures such as body fluids accounts for more than about 60% of the total induced current. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0095] Figure 1 Schematic diagram of the cross-section of the structure of the electrode tip segment in the electrode wire provided by the present invention in Embodiment 1 and Embodiment 2;

[0096] Figure 2 This is a schematic diagram of the overall three-dimensional structure of the MRI-compatible electrode wire provided by the present invention;

[0097] Figure 3a A schematic structural diagram of the conductive limiting member in Example 1 provided by the present invention;

[0098] Figure 3b A schematic structural diagram of a conductive limiting member in Example 2 provided by the present invention;

[0099] Figure 4 A cross-sectional view of the electrode sleeve in Example 1 and Example 2 provided by the present invention;

[0100] Figure 5 Schematic diagram of the three-dimensional structure of the spiral electrode in Example 1 and Example 2 provided by the present invention;

[0101] Figure 6aA schematic cross-sectional view of the induced current shunting structure of the limiter in Example 1 and Example 2 provided by the present invention;

[0102] Figure 6b A schematic longitudinal cross-sectional view of the induced current shunting structure of the limiter in Example 1 and Example 2 provided by the present invention;

[0103] Figure 7 A schematic diagram of the pulse direction of the normal stimulation pulses sent after the electrode wires are implanted in the human body in Examples 1 and 2 provided by the present invention;

[0104] Figure 8 Schematic diagram of the distribution of the induced electric field e when the electrode lead tip is exposed to a high-frequency energy field in Examples 1 and 2 provided by the present invention;

[0105] Figure 9a A schematic diagram of the internal structure of the electrode lead exposed to a high-frequency energy field after implantation in Examples 1 and 2 provided by the present invention;

[0106] Figure 9b This is a circuit diagram of the medical system exposed to a high-frequency energy field after the electrode wires are connected to the IMD in Examples 1 and 2 provided by the present invention.

[0107] Description of Figure Numbers:

[0108]

[0109]

[0110] The implementation, functional features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with embodiments. DETAILED DESCRIPTION

[0111] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0112] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0113] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution in which both A and B are satisfied. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0114] Example 1

[0115] An implantable lead is a medically implanted electrical wire that connects to a pacemaker, defibrillator, or other electrical stimulation device at one end and directly to the heart, brain, or other part of the body that requires electrical stimulation. The primary function of an implantable lead is to transmit tiny electrical pulses from the device to the desired body structure and to transmit the body's electrical activity back to the device.

[0116] In an MRI scanning environment, the electrode wire 300 is affected by the high-frequency energy field 6, which includes a changing gradient magnetic field G and RF high-frequency pulses B1 (e.g., frequencies of 64 MHz and 128 MHz). The high-frequency energy field 6 couples energy within the elongated electrode wire 300, generating an induced electric field e and an induced current I along the length of the wire. The electrode wire 300 is a conductor, and its length may be a multiple of the wavelength λ0 of the high-frequency energy field 6, resulting in an enhanced coupling effect and a larger internal induced current I. The electrode wire contacts the human tissue 4 through the spiral electrode 1 to form a loop, and the induced current I flows through the spiral electrode 1 to the human tissue 4. However, the small contact area between the spiral electrode and the human tissue 4 results in a high current density at the interface between the electrode tip and the tissue, which can cause a significant temperature rise in the spiral electrode 1, resulting in serious damage such as changes in the electrical stimulation threshold and tissue perforation. It can also cause the electrode wire 300 to emit erroneous pulses at unnecessary times and locations, inducing stimulation abnormalities.

[0117] To disperse the induced electric field e and shunt the induced current, the electrodes maintain a normal path under the working electrical pulses, with only a minimal amount of the working electrical pulse signal being shunted, ensuring normal treatment. The present invention provides an electrode lead suitable for various medical devices, particularly, but not limited to, defibrillators, pacemakers, or other electrical stimulation devices.

[0118] See Figure 1 and Figure 2 , Figure 1 A schematic cross-sectional view of the structure of an electrode tip section in an electrode wire in an embodiment of the present invention is shown. Figure 2 A schematic diagram of the overall three-dimensional structure of an MRI-compatible electrode wire in an embodiment of the present invention is shown.

[0119] The present invention provides an MRI-compatible implantable electrode lead with a shunt head structure. The electrode lead 300 includes:

[0120] The conductor body section 400 has a first end and a second end opposite to each other. The conductor body section 400 includes an outer insulating tube 91 and an outer conductor body 40, an inner insulating tube 90, and an inner conductor body 30 sequentially disposed within the outer insulating tube 91.

[0121] The electrode tip section 100 is provided at the first end of the lead body section 400; and the connector section 200 is provided at the second end of the lead body section 400 and connected to the medical device via a connector;

[0122] In this embodiment, if Figure 1 As shown, the electrode head segment 100 includes: a spiral electrode 1 electrically connected to the inner wire body 30, and a ring electrode 2 electrically connected to the outer wire body 40; the spiral electrode 1 is used to be fixed to the patient's targeted treatment site, and the ring electrode 2 is used to be immersed in the human body fluid 5. The spiral electrode 1 and the ring electrode 2 transmit the electrical signal emitted by the implanted medical device to the targeted treatment site to be electrically stimulated;

[0123] The spiral electrode 1 includes Figure 5 Shown are: a spiral electrode tip 1a and a spiral structure 1b; during implantation, the spiral electrode tip 1a rotates and penetrates into the human tissue 4 at the targeted treatment location; in addition, the spiral structure 1b is a multi-turn equidistant spiral structure. Under the action of the high-frequency energy field 6, the spiral structure 1b can act as a series inductor to generate a large impedance, thereby reducing the induced current flowing to the spiral electrode 1 and the human tissue 4, thereby reducing electrode heating;

[0124] The inductance calculation formula of the spiral structure 1b is:

[0125]

[0126] Wherein, μ0 is the vacuum permeability constant, μ0=4∏×10 -7, N is the number of spiral turns, A is the cross-sectional area of the spiral electrode wire, and l is the length of the spiral structure. As the number of turns of the spiral structure 1b increases, the approximate inductance L of the spiral electrode 1 increases, increasing the series impedance and thereby reducing the induced current. The number of spiral turns is 10, and the length of the spiral structure is 8 mm. Of course, this embodiment does not impose specific limitations on the number of spiral turns and the length of the spiral structure. In other embodiments, the number of spiral turns is 5 to 15, and the length of the spiral structure is 5 to 10 mm.

[0127] Under the action of the high-frequency energy field 6, an induced current I is induced inside the electrode wire, and the induced current I is concentrated at the tip, resulting in a larger current density. The shunt contact 1d increases the contact area between the spiral electrode 1 and the tissue, dispersing the current density J at the interface between the electrode tip 1a and the tissue, thereby reducing the induced current density flowing from the spiral electrode 1 to the human tissue 4, thereby reducing heating of the electrode in the tissue.

[0128] The calculation formula of the current density J is:

[0129] Where I is the induced current, n is the number of shunt contacts, and A is the area of a single shunt contact. The more shunt contacts there are, the larger the area, and the smaller the current density J at each contact.

[0130] The relationship between the current density J and the number of shunt contacts is: Q = I 2 R∝J 2

[0131] Where I is the induced current, R is the conductor resistance, and J 2 The calorific value Q is proportional to the current density J. The more shunt contacts there are and the larger their area, the more dispersed the induced current I is, and the smaller the current density J of a single contact is, thereby reducing the calorific value of the spiral electrode tip 1a and the shunt contact 1d, evenly dissipating the tissue heat and reducing the local heating temperature. The number of shunt contacts 1d and raised structures 1c is 20, the height of the raised structure 1c is 0.1mm, and the area of the shunt contact 1d is 0.08mm. 2 ; Of course, this embodiment does not impose any specific restrictions on its quantity, height, and area.

[0132] In this embodiment, if Figure 1As shown, the end of the inner wire body 30 is nested and fixed in the distal outer position of the electrode core shaft 70 away from the spiral electrode tip 1a, and is fixed to the rear developing ring 51; the electrode core shaft 70 is made of conductive material, and has paramagnetic or diamagnetic properties, as well as low magnetic susceptibility properties, to meet the compatibility requirements of magnetic resonance imaging technology. The electrode core shaft 70 is close to the proximal position of the spiral electrode tip 1a, and is connected to the front developing ring 50; and the front developing ring 50 is connected to the spiral electrode 1; the inner wire body 30 is driven to rotate in the inner insulating tube 90, so as to drive the spiral electrode 1 accommodated in the electrode sleeve 80 to be driven to extend and retract. As shown Figure 4 As shown, the specific method of telescopic movement is as follows: the electrode sleeve 80 is provided with a transmission latch 80c; the transmission latch 80c is transmission-connected to the spiral electrode 1, converting the rotational motion of the spiral electrode 1 into telescopic motion along the axial direction of the spiral electrode 1. The inner conductor 30 is welded to the rear developing ring 51 to achieve electrical connection.

[0133] In this embodiment, if Figure 1 As shown, the two conductive stoppers 60 are respectively arranged in a group corresponding to the front developing ring 50 and the rear developing ring 51 on either side of the length of the electrode core shaft 70. During the extension and retraction movement of the electrode core shaft 70 driven by the spiral electrode 1, the developing rings abut against the conductive stoppers 60 to limit the extension and retraction distance of the electrode core shaft 70. The position of the spiral electrode 1 is determined based on the developing distance between the conductive stoppers 60 and the developing rings. The spiral electrode 1, the conductive stoppers 60, the front developing ring 50, and the rear developing ring 51 are made of biocompatible developing materials with paramagnetic or diamagnetic properties and low magnetic susceptibility. In addition, the inner diameter of the inner contact hole 62 of the conductive limiting member 60 is smaller than the outer diameter of the front developing ring 50 and the rear developing ring 51 to limit the developing ring; the inner diameter of the inner contact hole 62 of the conductive limiting member 60 is close to the axial diameter of the electrode core shaft 70 to ensure that the two are electrically contacted and connected.

[0134] In addition, in order to change the overall distribution of the induced electric field e, the induced electric field strength of the spiral electrode tip 1a is dispersed and reduced, and the induced current density distributed in the human tissue 4 of the spiral electrode 1 is reduced, thereby reducing the heating of the human tissue 4 of the spiral electrode 1 and reducing thermal damage to the human tissue 4 during magnetic resonance scanning.

[0135] See Figure 3a ,as well as Figure 6a and Figure 6b , Figure 3a A schematic structural diagram of a conductive limiting member in an embodiment of the present invention is shown. Figure 6aA schematic cross-sectional view of the inductive current shunting structure of the limiter in an embodiment of the present invention is shown. Figure 6b A schematic longitudinal cross-sectional view of the inductive current shunting structure of the position-limiting member in an embodiment of the present invention is shown.

[0136] The electrode lead also includes:

[0137] The limiter induced current shunting structure 101 includes: the electrode sleeve 80, the electrode core shaft 70, and the conductive limiter 60;

[0138] The conductive stopper 60 has an inner contact hole 62 for the electrode core shaft 70 to pass through and electrically connect to the conductive stopper 60, so that the conductive stopper 60 is electrically connected to the electrode wire 300; the conductive stopper 60 is provided with an outer contact surface 61 and a molding surface 63 at a circumferential position; the outer contact surface 61 is in contact with the inner surface of the electrode sleeve 80; the molding surface 63 is formed with a sharp edge structure, and the end position of the sharp edge forms a diversion tip 64. Specifically, as Figure 3a As shown, the conductive limiter 60 is a columnar structure; the forming surface 63 is a groove formed on the outer peripheral wall of the conductive limiter 60 , and the diverter tip 64 is formed at the connection position between the forming surface 63 and the outer contact surface 61 .

[0139] Under the high-frequency energy field, an induced electric field e is induced inside the electrode wire.

[0140] The distribution formula of the induced electric field e is:

[0141]

[0142] Where r is the conductor curvature radius, and e is the induced electric field; the induced electric field e is inversely proportional to the curvature radius r. The curvature radius r at the edge of the shunt tip 64 and the molding surface 63 is extremely small. The shunt tip 64 produces a tip effect, which enhances the electric field intensity at the shunt tip, causing heating at the tip. The induced electric field e concentrates at the edge of the shunt tip 64 and the molding surface 63, changing the overall distribution of the induced electric field e, thereby dispersing and reducing the induced electric field intensity of the spiral electrode 1, thereby reducing heating of human tissue at the spiral electrode.

[0143] In addition, there is at least one forming surface 63 on the conductive limiter 60, and there are at least two diversion tips 64 on the conductive limiter 60; the number of the conductive limiters 60 is at least two; multiple conductive limiters 60 can enhance the induced electric field concentration and enhance the induced electric field weakening effect at the position of the spiral electrode tip 1a; the conductive limiter 60 is located on the side of the spiral electrode 1 away from the human tissue 4 to avoid the conductive limiter 60 that diverts heat from contacting the tissue and causing secondary damage.

[0144] Furthermore, if Figure 4 As shown, the fixed step 80b of the electrode sleeve 80 and the electrode insulating member 85 form a fixed space at the end facing the spiral electrode tip 1a. This fixed space is used to accommodate and position the conductive limiter 60. The conductive limiter 60 is located near the spiral electrode tip 1a and is abutted and connected to the fixed step 80b on the electrode sleeve 80. The conductive limiter 60 is located away from the spiral electrode tip 1a and is abutted and connected to the electrode insulating member 85. In addition, the outer contact surface 61 of the conductive limiter 60 is in contact with the inner wall of the dielectric segment 80a of the electrode sleeve 80, and the outer surface of the dielectric segment 80a contacts the human body fluid 5. The conductive limiter 60 and the electrode core shaft 70 constitute the first pole of the equivalent capacitor C1, and the human body fluid 5 constitutes the second pole of the equivalent capacitor C1. At least a portion of the dielectric segment 80a is an intermediate dielectric material. In the present invention, unlike the spiral electrode 1 contacting the human tissue 4, the conductive limiter 60 is isolated from the human body fluid 5 by a dielectric segment 80a. There is a temperature difference between the conductive limiter 60 and the human body fluid 5. Heat is effectively dissipated through heat transfer with the human body fluid 5, thereby reducing the heat generation of the electrode and preventing heat from being transferred to the tissue.

[0145] In the present invention, in order to achieve insulation sealing, as Figure 1 As shown, an insulating seal 55 is further provided between the two conductive limiters 60 , and the insulating seal 55 is tightly fitted with the conductive limiters 60 to squeeze the insulating seal 55 to fit with the inner cavity wall of the electrode sleeve 80 to form a sealing structure.

[0146] In the present invention, in order to achieve the insulation between the inner conductor 30 and the outer conductor 40. Figure 1As shown, the outer conductor body 40 is nested in the outer conductor body support section at a position away from the spiral structure 1b; the outer conductor body 40 has a lumen therein, through which the inner insulating tube 90 passes. The electrode insulator 85 is fixedly connected to the inner hole of the ring electrode 2 on the side away from the spiral electrode tip 1a; the inner insulating tube 90 extends into the inner hole of the electrode insulator 85 on the side away from the spiral electrode tip 1a and is fixed to the electrode insulator 85, thereby insulating the inner conductor of the electrode lead 300 from the ring electrode 2 and the outer conductor body 40.

[0147] Furthermore, the outer insulating tube 91 passes through the outer side of the outer wire body 40 and is fixedly connected to the outer wall step of the ring electrode 2; the electrode insulating member 85 is close to the side of the spiral electrode tip 1a, and the outer wall surface of the electrode insulating member 85 is fixed to the dielectric section 80a of the electrode sleeve 80; and the end of the electrode sleeve 80 facing the spiral electrode tip 1a is fixed with a drug plug 3.

[0148] In this embodiment, if Figure 9a and Figure 9b As shown. Among them, Figure 9a The diagram shows the internal structure of the electrode lead after implantation and exposure to a high-frequency energy field; Figure 9b A circuit diagram of a medical system exposed to a high-frequency energy field after the electrode leads are connected to the IMD is shown.

[0149] The conductive limiter 60 and the electrode core shaft 70 constitute the first pole of the equivalent capacitor C1, and the human body fluid 5 is the second pole of the equivalent capacitor C1;

[0150] The electrode wire 300 is fixed to the patient's targeted treatment site through the spiral electrode 1. When the electrode wire is in normal working condition: the stimulation pulse emitted by the IMD is transmitted to the spiral electrode 1 through the inner wire body 30, enters the human tissue 4 and completes the electrical stimulation; the stimulation pulse is transmitted to the ring electrode 2 through the human body fluid 5, and then returns to the IMD through the outer wire body 40 to form a loop; wherein, the stimulation pulse emitted by the IMD is in low frequency or DC form, and the equivalent capacitor C1 is in an open circuit state; the electrode sleeve 80 of insulating material realizes insulation between the conductive limiter 60 and the human body fluid 5; the pulse transmitted by the inner wire body 30 is transmitted to the spiral electrode 1 through the electrode core shaft 70 and the conductive limiter 60, and the electrical pulse is transmitted to the human tissue 4, and only a negligible amount or no stimulation pulse is diverted.

[0151] The electrode wire 300 is fixed to the patient's targeted treatment site through the spiral electrode 1. When the electrode wire is in an MRI scanning environment: under the high-frequency energy field 6, an induced current is formed in the electrode wire 300, and the conductive limiter 60 is capacitively coupled with the human body fluid 5; the impedance of the equivalent capacitor C1 is in the lowest state, that is, the impedance is extremely small. When the induced current I on the IMD and the electrode is transmitted to the conductive limiter 60 through the electrode core shaft, the induced current I1 is transmitted along a path with lower impedance to the human body fluid 5 surrounding the electrode sleeve 80, and the induced current I2 is transmitted to the human tissue 4 through the spiral electrode 1, and then the current returns to the IMD through the human tissue 4 and the human body fluid 5; wherein, the induced current I1 is greater than the induced current I2; the wall thickness value of the dielectric segment 80a and the size and number of the conductive limiters 60 are adjusted to adjust the capacitance value of the equivalent capacitor C1 to obtain the ability to shunt the induced current under a wide-spectrum high-frequency energy field.

[0152] Therefore, the limiter induced current shunting structure 101 significantly reduces the induced current flowing to the spiral electrode 1, reducing the heat generated at the electrode tip and the tissue interface. The shunted induced current flows through the human body fluid 5 to generate Joule heat, and the human body fluid 5 has a large specific heat capacity, so the body fluid temperature rise caused by Joule heat is small, which can avoid damaging the human body fluid 5 and the human tissue 4. At the same time, Figure 8 As shown, the special shape of the conductive stopper 60 can concentrate the induced electric field e in the high-frequency energy field 6, thereby enhancing the ability to shunt the induced current at high frequencies. By adjusting the wall thickness of the dielectric segment 80a, the size and number of the conductive stoppers 60, the capacitance of the equivalent capacitor C1 can be adjusted, thereby achieving satisfactory shunt capability for the induced current in the high-frequency energy field.

[0153] The dielectric segment 80a has a thinner wall thickness to reduce the inter-electrode spacing of the equivalent capacitor C1, increase the capacitance value of the equivalent capacitor C1, and enhance the ability to shunt induced current under high-frequency energy fields; at the same time, enhance the heat transfer effect between the conductive limiter 60 and human body fluids.

[0154] In addition, if Figure 9b As shown, the conductive limiter 60 and the electrode core shaft 70 constitute the first pole of the equivalent capacitor C1, and the human body fluid 5 is the second pole of the equivalent capacitor C1;

[0155] The IMD is connected to the electrode circuit 7 of the electrode wire 300. The electrode circuit 7 includes: a series resistor, a series impedance, a series inductor, and a parallel capacitor. The human tissue 4 and the human body fluid 5 form a resistance R, the inner wire body 30 forms a series resistor R1, the outer wire body 40 forms a series resistor R2, the resistance of the series conductor inside the electrode head segment 100 is a series resistor R3, and the spiral electrode 1 forms an equivalent series inductor L1 under the high-frequency energy field 6.

[0156] The electrode lead 300 is fixed to the patient's targeted treatment site via the spiral electrode 1. When the electrode lead is in normal working condition, the electrical pulse is transmitted to the targeted tissue via the spiral electrode 1, then transmitted to the ring electrode 2 via the human tissue 4 and the human body fluid 5, and then returns to the IMD to form a loop. The stimulation pulse emitted by the IMD is in low-frequency or DC form, and the equivalent capacitor C1 is in an open-circuit state. The spiral structure 1b exhibits the properties of a conductor at low frequencies and does not weaken the strength of the electrical pulse signal.

[0157] The electrode lead 300 is fixed to the patient's targeted treatment area via the spiral electrode 1. When the electrode lead is in an MRI scanning environment, an induced current I is generated within the electrode circuit 7. This induced current I sequentially passes through the series resistor R1 representing the resistance of the inner wire body 30 and the series resistor R2 representing the resistance of the electrode core shaft 70 and the wire stopper 60. Due to the extremely high frequency of the high-frequency energy field 6 and the extremely low impedance of the equivalent capacitor C1, the equivalent capacitor C1 is in a short-circuit state. The induced current I1 in the induced current I flows through the wire stopper 60 represented by the series resistor R2 and through the equivalent capacitor C1 to the ground, flowing to the human body fluid 5. The induced current I2 is transmitted through the spiral electrode 1 to the human tissue 4, forming the resistance R. The equivalent series inductor L1 formed by the spiral electrode 1 has a large impedance, further weakening the magnitude of the induced current I2 and increasing the induced current I1 in the human body fluid 5. When I2 flows through the resistance R represented by the human tissue 4, it generates Joule heat, causing tissue temperature to rise. Although induced current I2 still flows into human tissue 4, it is reduced by the shunt and the resistance of series inductor L1. As a result, despite the small contact area between spiral electrode 1 and human tissue 4, the current density at the interface between spiral electrode tip 1a and tissue is low, keeping the temperature rise at the location of human tissue 4 within an acceptable range. In this case, induced current I1 is greater than induced current I2.

[0158] Of course, this embodiment does not specifically limit the method of driving the spiral electrode 1 to be extended and retracted. In other embodiments, the spiral electrode 1 can also be driven to extend and retract by other methods such as by a toggle claw connected to the spiral electrode 1 in a transmission manner.

[0159] Of course, this embodiment does not specifically limit the connection method between the inner conductor body 30 and the rear developing ring 51. In other embodiments, the inner conductor body 30 and the rear developing ring 51 can also be fixed by crimping or clamping to achieve electrical connection.

[0160] Of course, this embodiment does not specifically limit the specific material of the electrode core shaft 70. In other embodiments, the electrode core shaft 70 includes: one or more combinations of titanium, titanium alloy, platinum alloy, non-magnetic nickel-cobalt-chromium alloy, and conductive polymer materials.

[0161] Of course, this embodiment does not specifically limit the spiral electrode 1, the conductive limiter 60, the front developing ring 50 and the rear developing ring 51. In other embodiments, the spiral electrode 1, the conductive limiter 60, the front developing ring 50 and the rear developing ring 51 are biocompatible developing materials with paramagnetic or diamagnetic properties and low magnetic susceptibility, specifically including one or more of platinum iridium, platinum alloy, and tantalum.

[0162] Of course, this embodiment does not specifically limit the fixing method of the electrode insulating member 85 and the ring electrode 2, the fixing method of the inner insulating tube 90 and the electrode insulating member 85, the fixing method of the outer insulating tube 91 and the ring electrode 2, and the fixing method of the electrode sleeve 80 and the drug plug 3. In other embodiments, the electrode insulating member 85 and the ring electrode 2 are bonded and fixed; the inner insulating tube 90 and the electrode insulating member 85 are bonded and fixed; the outer insulating tube 91 and the ring electrode 2 are bonded and fixed; the electrode insulating member 85 and the dielectric segment 80a are bonded and fixed; and the electrode sleeve 80 and the drug plug 3 are bonded and fixed. The bonding and fixing method is bonding by injecting a biocompatible polymer adhesive, and the polymer adhesive includes: biocompatible silicone adhesive and polyurethane adhesive.

[0163] Of course, this embodiment does not specifically limit the shape structure of the conductive limiter 60. In other embodiments, the forming surface 63 of the conductive limiter 60 can also be: polygonal, C-shaped or multi-angled; the style of the forming surface 63 is an angle less than or equal to 180°.

[0164] Of course, this embodiment does not specifically limit the specific angle of the bevel 65 on the conductive limiter 60. In other embodiments, the side wall position of the end face of the conductive limiter 60 of the columnar structure is also provided with a bevel 65 for enhancing the electric field focusing ability of the diversion tip 64; the bevel 65 is 0.05mm to 1mm.

[0165] Of course, this embodiment does not specifically limit the specific position of the shunt tip 64. In other embodiments, the shunt tip 64 for producing the tip effect can be set on the electrode core shaft 70, the front developing ring 50, the rear developing ring 51 and the ring electrode 2 as needed.

[0166] Of course, this embodiment does not impose a specific limit on the number of conductive stoppers 60 provided corresponding to the front developing ring 50 and the rear developing ring 51. In other embodiments, the conductive stoppers 60 may be grouped into three or more groups, and there is no specific limit on the specific combination of conductive stoppers 60. The conductive stoppers 60 are provided in groups corresponding to the front developing ring 50 and the rear developing ring 51 on both sides of the length direction of the electrode core shaft 70.

[0167] Example 2

[0168] The specific difference between this embodiment and the first embodiment lies in the specific structure of the conductive limiter 60 .

[0169] like Figure 1 As shown, the two conductive stoppers 60 are respectively arranged in a group corresponding to the front developing ring 50 and the rear developing ring 51 on either side of the length of the electrode core shaft 70. During the extension and retraction movement of the electrode core shaft 70 driven by the spiral electrode 1, the developing rings abut against the conductive stoppers 60 to limit the extension and retraction distance of the electrode core shaft 70. The position of the spiral electrode 1 is determined based on the developing distance between the conductive stoppers 60 and the developing rings. The spiral electrode 1, the conductive stoppers 60, the front developing ring 50, and the rear developing ring 51 are made of biocompatible developing materials with paramagnetic or diamagnetic properties and low magnetic susceptibility. In addition, the inner diameter of the inner contact hole 62 of the conductive limiting member 60 is smaller than the outer diameter of the front developing ring 50 and the rear developing ring 51 to limit the developing ring; the inner diameter of the inner contact hole 62 of the conductive limiting member 60 is close to the axial diameter of the electrode core shaft 70 to ensure that the two are electrically contacted and connected.

[0170] In addition, in order to change the overall distribution of the induced electric field e, the induced electric field strength of the spiral electrode tip 1a is dispersed and reduced, and the induced current density distributed in the human tissue 4 of the spiral electrode 1 is reduced, thereby reducing the heating of the human tissue 4 of the spiral electrode 1 and reducing thermal damage to the human tissue 4 during magnetic resonance scanning.

[0171] See Figure 3b ,as well as Figure 6a and Figure 6b , Figure 3a A schematic structural diagram of a conductive limiting member in an embodiment of the present invention is shown. Figure 6a A schematic cross-sectional view of the inductive current shunting structure of the limiter in an embodiment of the present invention is shown. Figure 6b A schematic longitudinal cross-sectional view of the inductive current shunting structure of the position-limiting member in an embodiment of the present invention is shown.

[0172] The electrode lead also includes:

[0173] The limiter induced current shunting structure 101 includes: the electrode sleeve 80, the electrode core shaft 70, and the conductive limiter 60;

[0174] The conductive stopper 60 has an inner contact hole 62 for the electrode core shaft 70 to pass through and electrically connect to the conductive stopper 60, so that the conductive stopper 60 is electrically connected to the electrode wire 300; the conductive stopper 60 is provided with an outer contact surface 61 and a molding surface 63 at a circumferential position; the outer contact surface 61 is in contact with the inner surface of the electrode sleeve 80; the molding surface 63 is formed with a sharp edge structure, and the end position of the sharp edge forms a diversion tip 64. Specifically, as Figure 3b As shown, the conductive limiter 60 is an elliptical structure; the diversion tip 64 is formed on the circumferential position of the outer peripheral wall of the conductive limiter 60, and the outer contact surface 61 is a cross-section formed on the outer peripheral wall of the conductive limiter 60.

[0175] In addition, there is at least one forming surface 63 on the conductive limiter 60, and there are at least two diversion tips 64 on the conductive limiter 60; the number of the conductive limiters 60 is at least two; multiple conductive limiters 60 can enhance the induced electric field concentration and enhance the induced electric field weakening effect at the position of the spiral electrode tip 1a; the conductive limiter 60 is located on the side of the spiral electrode 1 away from the human tissue 4 to avoid the conductive limiter 60 that diverts heat from contacting the tissue and causing secondary damage.

[0176] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A magnetic resonance compatible implantable electrode lead with a shunt head structure, the electrode lead (300) comprising: A wire main body section (400) has a first end and a second end opposite to each other, the wire main body section (400) comprising an outer insulating tube (91) and an outer wire body (40), an inner insulating tube (90) and an inner wire body (30) sequentially arranged in the outer insulating tube (91); The electrode head section (100) is provided at the first end of the wire main section (400); and the connector section (200) is provided at the second end of the wire main section (400) and is connected to the medical device via a connector; characterized in that: The electrode head section (100) comprises: a spiral electrode (1) electrically connected to the inner conductor (30), and a ring electrode (2) electrically connected to the outer conductor (40); the spiral electrode (1) and the ring electrode (2) transmit electrical signals emitted by the implanted medical device to a targeted treatment site to be electrically stimulated; The spiral electrode (1) comprises: a spiral structure (1b); the spiral structure (1b) is a spiral structure with multiple turns and equal spacing; under the action of a high-frequency energy field (6), the spiral structure (1b) can act as a series inductor to generate a large impedance, thereby reducing the induced current flowing to the spiral electrode (1) and human tissue (4), thereby reducing electrode heating; The inductance calculation formula of the spiral structure (1b) is: Wherein, μ0 is the vacuum permeability constant, μ0=4Π×10 -7 , N is the number of spiral turns, A is the cross-sectional area of the spiral electrode wire, and l is the length of the spiral structure.

2. The electrode lead according to claim 1, wherein: The spiral electrode (1) further comprises: a spiral electrode tip (1a); during the implantation process, the spiral electrode tip (1a) is rotated and inserted into the human tissue (4) at the targeted treatment location; The end of the inner wire body (30) is nested and fixed in a distal outer position of the electrode core shaft (70) away from the spiral electrode tip (1a), and is fixed to the rear developing ring (51); the electrode core shaft (70) is close to the proximal end of the spiral electrode tip (1a) and is connected to the front developing ring (50); and the front developing ring (50) is connected to the spiral electrode (1); The inner conductor (30) is driven to rotate in the inner insulating tube (90), thereby driving the spiral electrode (1) accommodated in the electrode sleeve (80) to move in a driven manner.

3. The electrode lead according to claim 2, wherein: A transmission tooth (80c) is provided in the electrode sleeve (80); the transmission tooth (80c) is transmission-connected to the spiral electrode (1) to convert the rotational motion of the spiral electrode (1) into a telescopic motion along the axial direction of the spiral electrode (1).

4. The electrode lead according to claim 2, characterized in that The inner conductor (30) is fixed to the rear developing ring (51) by welding, crimping or clamping to achieve electrical connection; and / or the inner conductor (30) is fixed to the electrode core shaft (70) by welding, crimping or clamping to achieve electrical connection.

5. The electrode lead according to claim 1, characterized in that The number of turns of the spiral is 5 to 15; and / or the length of the spiral structure is 5 mm to 10 mm.

6. The electrode lead according to claim 1, characterized in that A convex structure (1c) is arranged at a circumferential position of the spiral structure (1b), and an end position of the convex structure (1c) has a shunt contact (1d) for reducing current density; and / or, The protruding structure (1c) may be: conical, polygonal or dot-shaped; the protruding structure (1c) may be directed toward or away from the spiral tip (1a); and / or, The protruding structures (1c) on the spiral electrode (1) are evenly and symmetrically arranged on the spiral structure (1b) in the circumferential direction; and / or, There is at least one protruding structure (1c) on the spiral electrode (1), and there is at least one shunt contact (1d) on the spiral electrode (1); and / or, The protrusion structure (1c) is a micro-protrusion with a protrusion height of 0.02-0.2 mm, and the area of the shunt contact (1d) is 0.01-0.1 mm. 2 .

7. The electrode lead according to claim 6, characterized in that Under the action of the high-frequency energy field (6), an induced current I is induced inside the electrode wire, and the shunt contact (1d) can disperse the current density J at the junction of the electrode tip (1a) and the tissue, so as to reduce the induced current density flowing from the spiral electrode (1) to the human tissue (4), thereby reducing the heating of the electrode in the tissue; The relationship between the current density J and the number of shunt contacts is: Where I is the induced current, n is the number of shunt contacts, and A is the area of a single shunt contact. The more shunt contacts there are, the larger the area and the smaller the current density J. The calculation formula for the heat generated by the induced current I is: Q = I 2 R∝J 2 Where I is the induced current, R is the conductor resistance, and J 2 is the current density; the calorific value Q is proportional to the current density J.

8. The electrode lead according to claim 2, characterized in that The electrode core shaft (70) is made of a conductive material and has paramagnetic or diamagnetic properties and low magnetic susceptibility performance to meet the compatibility requirements of magnetic resonance imaging technology; The electrode core shaft (70) comprises titanium and / or titanium alloy and / or platinum alloy and / or non-magnetic nickel-cobalt-chromium alloy and / or conductive polymer material.

9. The electrode lead according to claim 2 or 3, characterized in that: Also includes: The limiting member induction current shunting structure (101) comprises: the electrode sleeve 80, the electrode core shaft (70), and a conductive limiting member (60); The conductive stopper (60) has an inner contact hole (62) for the electrode core shaft (70) to pass through and to be in contact and electrically connected with the conductive stopper (60), so that the conductive stopper (60) is electrically connected to the electrode wire (300); The conductive limiter (60) is provided with an outer contact surface (61) and a molding surface (63) at a circumferential position; the outer contact surface (61) is bonded and connected to the inner surface of the electrode sleeve (80); a sharp edge structure is formed on the molding surface (63), and the end position of the sharp edge forms a diversion tip (64); Under the action of the high-frequency energy field (6), an induced electric field e is induced inside the electrode wire; The distribution formula of the induced electric field e is: Wherein, r is the curvature radius of the conductor, and e is the induced electric field; the induced electric field e is inversely proportional to the curvature radius r; the curvature radius r of the shunt tip (64) is relatively small, which easily produces a tip effect, thereby increasing the electric field intensity at the shunt tip position, thereby changing the overall distribution of the induced electric field e.

10. The electrode lead according to claim 9, characterized in that: The fixed step (80b) of the electrode sleeve (80) and the end of the electrode insulating member (85) facing the spiral electrode tip (1a) form a fixed space, and the fixed space is used to accommodate and positionally fix the conductive limiting member (60); The outer contact surface (61) of the conductive limiter (60) is in contact with the inner wall of the dielectric section (80a) of the electrode sleeve (80), and the outer surface of the dielectric section (80a) contacts human body fluid (5).

11. The electrode lead according to claim 9, characterized in that An insulating seal (55) is also provided between any two of the conductive limiters (60), and the insulating seal (55) is tightly fitted with the conductive limiters (60) to squeeze the insulating seal (55) and fit the inner cavity wall of the electrode sleeve (80) to form a sealing structure.

12. The electrode lead according to any one of claims 9 to 11, characterized in that: The conductive limiting member (60) is located close to the spiral electrode tip (1a) and is connected to the fixed step (80b) on the electrode sleeve (80) for abutment and limitation; the conductive limiting member (60) is located away from the spiral electrode tip (1a) and is connected to the electrode insulating member (85) for abutment and limitation.

13. The electrode lead according to any one of claims 9 to 11, characterized in that: At least two of the conductive limiters (60) in any group are respectively arranged corresponding to the front developing ring (50) and the rear developing ring (51) at both sides of the length direction of the electrode core shaft (70); During the process of the spiral electrode (1) driving the electrode core shaft (70) to extend and retract, the developing ring abuts against the conductive limiting member (60) to limit the extension and retraction distance of the electrode core shaft (70); and the position of the spiral electrode (1) is positioned according to the developing distance between the conductive limiting member (60) and the developing ring.

14. The electrode lead according to any one of claims 9 to 11, characterized in that: The spiral electrode (1), the conductive limiter (60), the front developing ring (50) and the rear developing ring (51) are made of conductive materials to meet the requirements of magnetic resonance imaging technology and development effects under X-ray irradiation; The spiral electrode (1), the conductive limiter (60), the front developing ring (50) and the rear developing ring (51) are made of biocompatible developing materials with paramagnetic or diamagnetic properties and low magnetic susceptibility, including platinum iridium and / or platinum alloy and / or tantalum.

15. The electrode lead according to any one of claims 9 to 11, characterized in that: The inner diameter of the inner contact hole (62) of the conductive limiting member (60) is smaller than the outer diameters of the front developing ring (50) and the rear developing ring (51), so as to limit the developing rings; and / or, The inner diameter of the inner contact hole (62) of the conductive limiting member (60) is approximately equal to the axial diameter of the electrode core shaft (70) to ensure electrical contact between the two.

16. The electrode lead according to claim 1, characterized in that The outer conductor body (40) is nested on the outer conductor body support section at a position away from the spiral structure (1b); The outer conductor (40) has a cavity therein, and the inner insulating tube (90) passes through the cavity to ensure that the inner conductor (30) and the outer conductor (40) are insulated from each other.

17. The electrode lead according to claim 10, characterized in that The electrode insulating member (85) is fixedly connected to the inner hole of the ring electrode (2) on a side away from the spiral electrode tip (1a); the inner insulating tube (90) extends into the inner hole of the electrode insulating member (85) on a side away from the spiral electrode tip (1a) and is fixed to the electrode insulating member (85) to form insulation between the ring electrode (2) and the outer wire body (40) and the inner conductor of the electrode wire (300).

18. The electrode lead according to claim 17, characterized in that The outer insulating tube (91) passes through the outside of the outer wire body (40) and is fixedly connected to the outer wall step of the ring electrode (2); the electrode insulating member (85) is close to the side of the spiral electrode tip (1a), and the outer wall surface of the electrode insulating member (85) is fixed to the dielectric section (80a) of the electrode sleeve (80); and a drug plug (3) is fixed to the end of the electrode sleeve (80) facing the spiral electrode tip (1a).

19. The electrode lead according to claim 18, characterized in that The electrode insulating member (85) is bonded and fixed to the ring electrode (2); and / or, the inner insulating tube (90) is bonded and fixed to the electrode insulating member (85); and / or, the outer insulating tube (91) is bonded and fixed to the ring electrode (2); and / or, the electrode insulating member (85) is bonded and fixed to the dielectric segment (80a); and / or, the electrode sleeve (80) is bonded and fixed to the drug plug (3); The bonding and fixing method is to inject a biocompatible polymer adhesive for bonding. The polymer adhesive includes: biocompatible silicone adhesive and polyurethane adhesive.

20. The electrode lead according to claim 9, characterized in that The conductive stopper (60) is a columnar structure; the forming surface (63) is a groove formed on the outer peripheral wall of the conductive stopper (60); the diversion tip (64) is formed at the connection position between the forming surface (63) and the outer contact surface (61); or, The conductive limiting member (60) is an elliptical structure; the diversion tip (64) is formed at a circumferential position of the outer peripheral wall of the conductive limiting member (60); and the outer contact surface (61) is a section formed on the outer peripheral wall of the conductive limiting member (60).

21. The electrode lead according to claim 20, characterized in that The forming surface (63) of the conductive limiter (60) may also be: polygonal, C-shaped or multi-angled; the forming surface (63) may have an angle less than or equal to 180°; and / or, There is at least one molding surface (63) on the conductive limiting member (60), and there are at least two diversion tips (64) on the conductive limiting member (60); and / or, The number of the conductive limiting members (60) is at least two; and / or, The conductive limiting member (60) is located on a side of the spiral electrode (1) away from the human tissue (4).

22. The electrode lead according to claim 20, characterized in that The side wall position of the end face of the conductive limiter (60) of the columnar structure is further provided with an oblique cut surface (65) for enhancing the electric field focusing capability of the diversion tip (64); the oblique cut surface (65) is 0.05 mm to 1 mm.

23. The electrode lead according to claim 9, characterized in that The electrode core shaft (70) and / or the front developing ring (50) and / or the rear developing ring (51) and / or the ring electrode (2) have a shunt tip (64) for generating a tip effect.

24. The electrode lead according to claim 9, characterized in that The conductive limiter (60) and the electrode core shaft (70) form a first pole of the equivalent capacitor C1, and the human body fluid (5) forms a second pole of the equivalent capacitor C1; The electrode wire (300) is fixed to the patient's targeted treatment site via the spiral electrode (1). When the electrode wire is in a normal working state, a stimulation pulse emitted by the IMD is transmitted to the spiral electrode (1) via the inner wire body (30), enters the human tissue (4), and completes the electrical stimulation; the stimulation pulse is conducted to the ring electrode (2) via the human body fluid (5), and then returns to the IMD via the outer wire body (40) to form a loop. The stimulation pulses emitted by the IMD are in a low-frequency or DC form, and the equivalent capacitor C1 is in an open-circuit state; the electrode sleeve (80) made of insulating material realizes insulation between the conductive limiter (60) and the human body fluid (5); the pulses transmitted by the inner conductor (30) are transmitted to the spiral electrode (1) through the electrode core shaft (70) and the conductive limiter (60), and the electric pulses are transmitted to the human tissue (4).

25. The electrode lead according to claim 9, characterized in that The conductive limiter (60) and the electrode core shaft (70) form a first pole of the equivalent capacitor C1, and the human body fluid (5) forms a second pole of the equivalent capacitor C1; The electrode wire (300) is fixed to the patient's targeted treatment site through the spiral electrode (1). When the electrode wire is in an MRI scanning environment, an induced current is formed in the electrode wire (300) under the high-frequency energy field (6), and the conductive limiter (60) and the human body fluid (5) are capacitively coupled; the impedance of the equivalent capacitor C1 is at a minimum state, and when the induced current I on the IMD and the electrode is transmitted to the conductive limiter (60) through the electrode core shaft, the induced current I1 is transmitted along a path with low impedance to the human body fluid (5) surrounding the electrode sleeve (80), and the induced current I2 is transmitted to the human tissue (4) through the spiral electrode (1), and then the current returns to the IMD through the human tissue (4) and the human body fluid (5); wherein the induced current I1 is greater than the induced current I2; The wall thickness of the dielectric section (80a) and the size and number of the conductive limiter (60) are adjusted to adjust the capacitance value of the equivalent capacitor C1, thereby obtaining the ability to shunt the induced current under a wide-spectrum high-frequency energy field.

26. The electrode lead according to claim 25, characterized in that The electrode sleeve (80) is made of a biocompatible insulating material, including polyurethane, PEEK, polyimide, PTFE; and / or, The dielectric segment (80a) has a wall thickness of 0.05 mm to 0.5 mm; and / or, There are at least two conductive limiting members (60), and the plurality of conductive limiting members (60) are spliced into an integrated structure; and / or, The thickness of each conductive limiting member (60) is 0.2 mm to 1 mm, and the area of the external contact surface (61) is 2 mm. 2 Up to 10mm 2 and / or, The conductive limiting member (60) is tightly connected to the inner cavity hole of the dielectric section (80a), and the diameter of the conductive limiting member (60) is 1.5 mm to 2.5 mm.

27. The electrode lead according to claim 9, characterized in that The conductive limiter (60) and the electrode core shaft (70) form a first pole of the equivalent capacitor C1, and the human body fluid (5) forms a second pole of the equivalent capacitor C1; The IMD is connected to the electrode circuit (7) of the electrode wire (300), and the electrode circuit (7) includes: a series resistor, a series impedance, a series inductor, and a parallel capacitor; the human tissue (4) and the human body fluid (5) form a resistor R, the inner wire body (30) forms a series resistor R1, the outer wire body (40) forms a series resistor R2, the resistance of the internal series conductor of the electrode head segment (100) is a series resistor R3, and the spiral electrode (1) forms an equivalent series inductor L1 under the high-frequency energy field (6); The electrode wire (300) is fixed to the patient's targeted treatment site via the spiral electrode (1). When the electrode wire is in normal working condition, the electric pulse is transmitted to the targeted tissue via the spiral electrode (1), and then transmitted to the ring electrode (2) via the human tissue (4) and the human body fluid (5) and returns to the IMD to form a loop. The stimulation pulse emitted by the IMD is in low frequency or DC form, and the equivalent capacitor C1 is in an open circuit state. The spiral structure (1b) exhibits the properties of a wire at low frequency and does not weaken the strength of the electric pulse signal. The electrode wire (300) is fixed to the patient's targeted treatment site via a spiral electrode (1). When the electrode wire is in an MRI scanning environment, an induced current I is induced in the electrode circuit (7), and the induced current I sequentially passes through the series resistor R1 and the series resistor R2; the equivalent capacitor C1 is in a short-circuit state, and an induced current I1 in the induced current I passes through the series resistor R2 and the equivalent capacitor C1 to the ground and flows to the human body fluid (5); the induced current I2 is transmitted through the spiral electrode (1) to the resistor R formed by the human tissue (4); wherein, the induced current I1 is greater than the induced current I2.

28. A medical device, characterized in that The medical equipment includes: A machine body having a connection interface; and An electrode wire, wherein the electrode wire is the electrode wire according to any one of claims 1 to 27, and a connector of the electrode wire is inserted into the connection interface.

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