The instant disclosure relates to catheters, such as catheters for diagnosis or treatment of various medical conditions.
Catheters have been used for cardiac medical procedures for many years. Catheters can be used, for example, to diagnose and treat cardiac arrhythmias, while positioned at a specific location within a body that is otherwise inaccessible without a more invasive procedure. In general, mapping catheters can be used for diagnosing electrophysiology and generating three-dimensional models of tissue within the body. Other catheters, such as ablation catheters can be used for treatment of some cardiac arrhythmias. Some catheters are configured to perform both mapping and ablation functions. In relation to mapping catheters, a tip portion of the catheter often has one or more electrodes for measuring electrophysiological signals (e.g., biosignals) within tissue. Various configurations of mapping catheters exist. Some mapping catheters have a single electrode for performing electrophysiological measurements whereas other mapping catheters can include a plurality of electrodes, such as an array of electrodes for collecting simultaneous measurements at various locations along the tissue. It can be desirable to increase the number of electrodes on the catheter in order to collect a greater amount of measurement data. In some instances, the collection of simultaneous data can also be advantageous for mapping and diagnosis purposes.
Because of geometrical confines within the body, both the placement of electrodes and use of an increased number of electrodes on a catheter can create challenges. Reducing the size and spacing of the electrodes can provide for an increase in the number and density of electrodes on the catheter. However, reducing the size of the electrodes correspondingly reduces the surface area of the electrodes for collecting electrophysiological measurement. As the size of the electrodes decreases, the electrical performance of the electrodes can be affected in some instances. The foregoing discussion is intended only to illustrate the present field and should not be taken as a disavowal of claim scope.
The instant disclosure relates to high-density mapping catheter tips and to map-ablate catheter tips for diagnosing and treating cardiac arrhythmias via, for example, radio-frequency (RF) ablation. In particular, the instant disclosure relates to flexible high-density mapping catheter tips, and to flexible ablation catheter tips that can also have onboard high-density mapping electrodes. In some embodiments, the catheters may include irrigation.
In an example, a catheter for electrophysiological measurement can include a catheter shaft including a proximal end and a distal end. An electrical conductor attached to the catheter. In an example, a catheter tip portion can be located at the distal end of the catheter shaft. The catheter tip portion can include an electrical conductor and an electrode. In some examples, the electrical conductor can be a trace along a flexible circuit. The electrical conductor can be configured to be communicatively coupled to an electronic control unit (ECU). The electrode can be disposed on the electrical conductor. A contact surface area of the electrode can include an impedance reduction layer.
In various examples, the impedance reduction layer can be a platinum coating or a platinum iridium coating. In some instances, the thickness of the impedance reduction layer can be between 1-5 μm or 1-30 μm (inclusively). The contact surface area of the electrode or impedance reduction layer can include, but is not limited to, 1.0 mm2, 0.5 mm2, or less. In an example, the impedance reduction layer can be configured to reduce the impedance at the electrode by at least fifty percent as compared to a similarly sized electrode without the impedance reduction layer. In another example, the impedance reduction layer can be configured to increase the biocompatibility of the electrode, for instance, as compared to an electrode including a contact surface area coated with gold. An intermediate layer (e.g., a gold layer) can be disposed between a copper layer of the electrical conductor and the impedance reduction layer. In a further example, the impedance reduction layer can include a surface texture having a surface roughness, such as a surface roughness between 1 and 30 μm.
In another example, a method of making a catheter including a reduced impedance electrode can include attaching an electrical conductor to the catheter, such as attaching the electrical conductor to a catheter tip portion located at a distal end of a catheter. The electrical conductor can be configured to be communicatively coupled to an electronic control unit (ECU). In a further example, the method can include disposing an impedance reduction layer on the electrical conductor. In an example, the method can include attaching a flexible circuit to a catheter, wherein the flexible circuit includes the electrical conductor and the impedance reduction layer. The electrical conductor can be disposed along a dielectric layer of the flexible circuit, and the impedance reduction layer can be disposed on the electrical conductor. In further examples, attaching the flexible circuit to the catheter can include attaching the flexible circuit to a spine of a basket catheter.
In an example, the impedance reduction layer can include a contact surface area configured as an electrode to make contact with tissue. In a further example, the impedance reduction layer can include a material selected from a group comprising platinum or platinum iridium.
In an example, the impedance reduction layer can include a thickness between 1-5 μm or 1 to 30 μm (inclusively). In some examples, the size of the contact surface area can include, but is not limited to, less than 1.0 mm2 or less than 0.5 mm2. In various examples, the flexible circuit can include a gold layer between a copper layer of the electrical conductor and the impedance reduction layer. In some instances, the impedance reduction layer can include a surface texture. For example, the surface texture can include a surface roughness between 1 and 30 μm. The surface texture can be applied by various means, such as formed using a laser.
The foregoing and other aspects, features, details, utilities, and advantages of the present disclosure will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.
Several embodiments of an electrode, such as an electrode for a flexible, high-density mapping catheter and map-ablate catheters as well as ablation therapy catheters are disclosed herein. In general, tip portions of these various catheters comprise one or more electrodes for measuring electrophysiological signals of a patient or for delivering ablation therapy to tissue of the patient. Reducing the size and spacing of the electrodes can provide for an increase in the number and density of electrodes along the tip portion, can allow for a reduction in the size of the tip portion itself, and can reduce the cost of fabrication. As the size of the electrodes is reduced, however, the impedance between the electrode and the respective tissue in contact with the electrode can be increased due to the reduction in surface area of the electrode. The present inventors have recognized that an electrode having an impedance reduction coating, such as platinum or platinum iridium (PtIr) surface coating, can reduce the impedance between the electrode and tissue contacting the electrode. Details of the various embodiments of the present disclosure are described below with specific reference to the figures.
The catheter 102 can include a handle 124, a cable connector or interface 126 at a proximal end of the handle 124, and a shaft 104 (also referred to herein as a catheter shaft). The shaft 104 can include a proximal end 130, a distal end 132. A tip portion 106 can be located at the distal end 132. The handle 124 provides a location for the physician to hold the catheter 102 and can further provide means for steering or guiding the shaft 104 within the body 112. For example, the handle 124 can include means to change the length of one or more pull wires extending through the catheter 102 from the handle 124 to the distal end 132 of shaft 104. The construction of the handle 124 can vary.
The shaft 104 can be made from conventional materials such as polyurethane and can define one or more lumens configured to house and/or transport electrical conductors 156, fluids, or surgical tools. The shaft 104 can be introduced into a blood vessel or other structure within the body 112 through a conventional introducer. The shaft 104 can then be steered or guided through the body 112 to a desired location such as the tissue 116 using guide wires or pull wires or other means known in the art including remote control guidance systems. The shaft 104 can also permit transport, delivery, and/or removal of fluids (including irrigation fluids and bodily fluids), medicines, and/or surgical tools or instruments. It should be noted that any number of methods can be used to introduce the shaft 104 to areas within the body 112. This can include introducers, sheaths, guide sheaths, guide members, guide wires, or other similar devices. For ease of discussion, the term introducer will be used throughout.
In some examples, the system 100 can include a positioning system, a display 140, and an electronic control unit (ECU) 142. The ECU 142 can include, but is not limited to, a central processing unit (CPU), graphics processing unit (GPU), microprocessor, application specific integrated circuit (ASIC), a field programmable gate array (FPGA), complementary metal-oxide-semiconductor (CMOS), or the like. In some examples, the ECU can include memory, such as random-access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM), dynamic random-access memory (DRAM), static random-access memory (SRAM), Flash memory, or the like.
The positioning system, such as the electric-field-based positioning system 136 or the magnetic-field-based positioning system 138, is provided to determine the position and orientation of the catheter 102, the tip portion 106, and similar devices within the body 112. For instance, the location or orientation of the tip portion 106 can be based on a fiducial or location of one or more electrodes of the tip portion 106, such as locational electrodes 134. In some examples, the locational electrodes 134 can include ring electrodes as shown in the example of
In the configuration shown in
In accordance with this exemplary electric-field-based positioning system 136 as depicted in
The magnetic-field-based positioning system 138 in this example employs magnetic fields to detect the position and orientation of the catheter 102 within the body 112. The system 138 can include the GMPS system made available by MediGuide, Ltd. and generally shown and described in, for example, U.S. Pat. No. 7,386,339 titled “Medical Imaging and Navigation System,” the entire disclosure of which is hereby incorporated by reference as though fully set forth herein. In such a system, a magnetic field generator 152 can be employed having three orthogonally arranged coils (not shown) to create a magnetic field within the body 112 and to control the strength, orientation, and frequency of the field. The magnetic field generator 152 can be located above or below the patient (e.g., under a patient table) or in another appropriate location. Magnetic fields are generated by the coils and current or voltage measurements for one or more position sensors associated with the catheter 102 are obtained. The measured currents or voltages are proportional to the distance of the sensors from the coils, thereby allowing determination of a position of the sensors within a coordinate system 154 of system 138.
As the catheter 102 moves within the body 112, and within the electric field generated by the electric-field-based positioning system 136, the voltage readings from the locational electrodes 134 change, thereby indicating the location of catheter 102 within the electric field and within the coordinate system 146 established by the system 136. The locational electrodes 134 can be adapted to communicate position signals to the ECU 142.
The catheter 102 can be configured to deliver treatment as well as geometric modeling or electrophysiological mapping. In some examples, the catheter 102 can include at least one electrode 108 configured to detect electrophysiological signals from the tissue or to provide energy for ablating the tissue. In an example, the electrode 108 can be communicatively coupled to the ablation generator 122 for delivery of electrical signals adapted to provide the ablation energy to the electrode 108. In some examples, the catheter 102 can be optionally connected to a fluid source 118 for delivering a biocompatible irrigation fluid such as saline through a pump 120. The pump 120 can include a fixed rate roller pump or variable volume syringe pump with a gravity feed supply from fluid source 118 as shown. The connector 126 provides mechanical, fluid, and electrical connections for conduits or cables extending from the pump 120 and the ablation generator 122. The catheter 102 can also include other conventional components not illustrated herein such as a temperature sensor, additional electrodes, and corresponding conductors or leads.
The ECU 142 provides a means for controlling the operation of various components of the system 100, including the catheter 102, the ablation generator 122, and magnetic generator 152 of the magnetic-field-based positioning system 138. The ECU 142 can also provide a means for determining electrophysiology characteristics (e.g., signals) of the tissue 116, the position and orientation of the catheter 102 relative to tissue 116 and the body 112, controlling the ablation of the tissue 116, or any combination thereof. The ECU 142 also provides a means for generating display signals used to control the display 140.
The display 140 is provided to convey information to a physician to assist in diagnosis and treatment. The display 140 can comprise one or more conventional computer monitors or other display devices. The display 140 can present a graphical user interface (GUI) to the physician. The GUI can include a variety of information including, for example, an image of the geometry of the tissue 116, electrophysiology data (e.g., maps of signals from the electrodes 108) associated with the tissue 116, graphs illustrating voltage levels over time for various locational electrodes 134, and images of the catheter 102 and other medical devices and related information indicative of the position of the catheter 102 and other devices relative to the tissue 116.
In the example of
In some examples, the one or more electrodes 208 can be located on a flexible circuit 210. The flexible circuit 210 can be attached to a shaft 204 of the catheter 202. For instance, as shown in the example of
In the example of
In a further example, the electrical conductor 414 can be directly attached to the substrate 404 of the catheter 402, such as a spine (e.g., spine 203), a shaft (e.g., shaft 104), or tip portion (e.g., tip portion 206) of the catheter 402. In an example, the electrical conductor 414 can be a metallic film that is applied to the substrate 404 with an adhesive. In various other examples, the electrical conductor 414 can be applied to the substrate 404 using electrodeposition, aerosol jet, vapor deposition, chemical deposition, or the like.
The impedance reduction layer 418 can be disposed on the electrical conductor 414. The impedance reduction layer 418 can reduce impedance between the tissue and the electrical conductor 414. As discussed further herein, the impedance reduction layer 418 can include platinum (Pt), platinum iridium (PtIr), or the like. Where the impedance reduction layer 418 includes platinum or platinum iridium, the impedance reduction layer 418 can increase the biocompatibility of the electrode as compared to electrodes including a gold plated contact surface area. In some examples, the impedance reduction layer 418 can be a surface texture or can be combined with a surface texture configured to reduce the impedance between the tissue and the electrode 408. The impedance reduction layer 418 can be disposed on the electrical conductor 414, for instance, by one or more means including, but not limited to, electrodeposition, vapor deposition, chemical deposition, aerosol jet, application of a foil, or other type method of applying the impedance reduction layer. The impedance reduction layer 418 can include a thickness T2 between 1 μm and 30 μm, preferably between 1 μm and 5 μm (inclusively). In a further example, the electrical conductor 414 can be directly attached to the substrate 404 of the catheter 402, such as or a spine (e.g., spine 203), a shaft (e.g., shaft 104), or tip portion (e.g., tip portion 206) of the catheter 402.
The second dielectric layer 416 can be disposed over the electrical conductor 414 to electrically insulate and protect the electrical conductor 414. The second dielectric layer 416 can include one or more apertures 420 to expose the electrode 408 to provide a contact surface area for placement against tissue within the body. In some examples, the aperture 420 can be constructed by laser cutting, punching, etching, or the like. In the example of
In a further example, a flexible circuit 510 can be attached to the catheter 502, such as the shaft, spine, or arm of the catheter 502. The flexible circuit 510 can be a single layer flexible circuit or a multi-layer flexible circuit as discussed herein. As shown in
The intermediate layer 522 can be disposed on the electrical conductor 514, and the impedance reduction layer 518 can be disposed on the intermediate layer 522. Accordingly, the intermediate layer 522 can be disposed between the electrical conductor 514 and the impedance reduction layer 518. In an example, the intermediate layer 522 can include a material that is compatible with the material of the electrical conductor 514 and the impedance reduction layer 518. For instance, the intermediate layer 522 can facilitate adhesion between the electrical conductor 514 and the impedance reduction layer 518. In an example, the intermediate layer 522 can include gold or a gold alloy. In a further example, the intermediate layer 522 can include electroless nickel immersion gold (ENIG) or electroless nickel electroless palladium immersion gold (ENEPIG). In a further example, the intermediate layer can include a platinum (Pt) layer and the impedance reduction layer can include a platinum iridium (PtIr) layer. One or more means of disposing the intermediate layer 522 on the electrical conductor 514 can include, but are not limited to, electrodeposition, vapor deposition, chemical deposition, aerosol jet, application of a foil, or other method of applying an intermediate metallic layer. In some examples, the intermediate layer 522 can include a thickness T3 between 1 μm and 25 μm (inclusively), preferably between 5 μm and 15 μm (inclusively), or more preferably 10 μm.
The impedance reduction layer 518 can reduce impedance between the tissue and electrical conductor 514. As discussed herein, the impedance reduction layer 518 can include platinum (Pt), platinum iridium (PtIr), or the like. In some examples, the impedance reduction layer 518 can be a surface texture or can be combined with a surface texture configured to reduce the impedance between the tissue and the electrode 508. The impedance reduction layer 518 can be deposited on the intermediate layer 522, for instance, by one or more means including, but not limited to, electrodeposition, vapor deposition, chemical deposition, aerosol jet, application of a foil (including an impedance reducing material as described herein), or other method of applying the impedance reduction layer 518. The impedance reduction layer 518 can include a thickness T4 between 1 μm and 30 μm or preferably between 1 μm and 5 μm (inclusively).
The second dielectric layer 516 can be disposed over the electrical conductor 514 to insulate and protect the electrical conductor 514. The second dielectric layer 516 can include one or more apertures 520 to expose the electrode 508 to provide a contact surface area for placement against tissue within the body. In some examples, the aperture 520 can be constructed by laser cutting, punching, etching, or the like. In the example of
In the example of
In some examples, a few of these electrodes can be slightly longer. For instance, the most-distal electrode 608 on the first outboard arm 624A can be slightly enlarged as is the most-proximal electrode 608 on the second outboard arm 624D. These slightly enlarged electrodes can be used, for example, for more precise localization of the flexible array in mapping and navigation systems. It is also possible to drive ablation current between these enlarged electrodes, if desired, for bipolar ablation, or, alternatively to drive ablation current in unipolar mode between one or both of these enlarged electrodes and, for example a patch electrode located on a patient (e.g., on the patient's back). Similarly, the electrodes (on this or any of the other paddle catheters) can be used to perform unipolar or bipolar ablation. Alternatively or concurrently, current could travel between one or more of the enlarged electrodes and any one or all of the electrodes 608. This unipolar or bipolar ablation can create specific lines or patterns of lesions.
In further examples, the tip portion 606 of a catheter 602 can be combined with, the planner array and catheter tip portions of US Patent Publication US 2015/0374252 titled “FLEXIBLE HIGH-DENSITY MAPPING CATHETER TIPS AND FLEXIBLE ABLATION CATHETER TIPS WITH ONBOARD HIGH-DENSITY MAPPING ELECTRODES,” the entire disclosure of which is hereby incorporated by reference as though fully set forth herein.
The surface texture 726 includes a pattern of plumes having a height including, but not limited to, 1 to 30 μm. In another example, the surface texture 826 can include a pattern of lines including a depth or height between 1 and 30 μm. In a further example, the surface texture 926 can be a pattern of dimples including a depth between 1 and 30 μm.
The electrode E4 includes a contact surface area of 0.5 mm2. In an example, the electrode E4 is disposed along a flexible circuit as shown and described herein. The electrode E4 includes the impedance reduction layer as described herein, such as in the examples of
The impedance 1130 at the electrodes E1, E2, and E3 can increase as the contact surface area of the electrodes decreases (e.g., from 2.5 mm2 to 0.5 mm2 in the examples of electrodes E1-E3), as shown in
In the example of
In an example, the resistance component, the reactance component, or both can be reduced by including the impedance reduction coating on the electrode. In another example, across a range of frequencies (e.g., 1 to 20,000 Hz) the resistance component, the reactance component, or combinations thereof can be reduced by inclusion of the impedance reduction layer. The impedance reduction layer can be used to reduce the impedance of the electrodes, generally, and in some examples, to mitigate the increased impedance of the reduced-size electrodes. Reducing the impedance at the electrodes can provide for increased fidelity of the electrophysiological signal measurement.
Although several embodiments have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit of the present disclosure. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the present teachings. The foregoing description and following claims are intended to cover all such modifications and variations.
Various embodiments (examples) are described herein of various apparatuses, systems, and methods. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims.
Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” “an embodiment,” or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” “in an embodiment,” or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features structures, or characteristics of one or more other embodiments without limitation.
It will be appreciated that the terms “proximal” and “distal” may be used throughout the specification with reference to a clinician manipulating one end of an instrument used to treat a patient. The term “proximal” refers to the portion of the instrument closest to the clinician and the term “distal” refers to the portion located furthest from the clinician. It will be further appreciated that for conciseness and clarity, spatial terms such as “vertical,” “horizontal,” “up,” and “down” may be used herein with respect to the illustrated embodiments. However, surgical instruments may be used in many orientations and positions, and these terms are not intended to be limiting and absolute.
Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2020/056234 | 7/2/2020 | WO |
Number | Date | Country | |
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62869779 | Jul 2019 | US |