Electrode configuration for arrhythmia diagnosis

Abstract

An apparatus includes a shaft and an end effector at a distal end of the shaft. The end effector is sized to fit within an anatomical passage within a cardiovascular system of a subject. The end effector includes at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals. Each electrode pair includes first and second electrodes separated from each other along a longitudinal axis by a gap region between the electrodes, the gap region having a gap length relative to the longitudinal axis such that a length of one of the electrodes along the longitudinal axis is equal to or greater than the gap length; and a ratio of an area defined by the gap area to an area of ​​one of the electrodes is equal to or less than 1.

Description

Background Art

[0001] Arrhythmias, such as atrial fibrillation, occur when an area of ​​cardiac tissue abnormally conducts electrical signals. Procedures used to treat arrhythmias involve surgically interrupting the conduction pathways for such signals. By selectively ablating cardiac tissue through the application of energy (e.g., radiofrequency (RF) energy), it may be possible to stop or modify the propagation of unwanted electrical signals from one part of the heart to another. The ablation process can provide a barrier to the unwanted electrical pathways by creating electrically insulating lesions or scar tissue.

[0002] Some catheter ablation procedures, particularly those for persistent atrial fibrillation, can be performed using electrophysiology (EP) mapping of target areas of abnormal electrical signals. Such EP mapping can include the use of sensing electrodes on a catheter (e.g., the same catheter used to perform the ablation). Such sensing electrodes can monitor electrical signals within the cardiovascular system to precisely locate the location of abnormally conducting tissue sites that cause arrhythmias. An example of an electrophysiological mapping system is described in U.S. Patent No. 5,738,096, entitled “Cardiac Electromechanics,” issued on April 14, 1998, the disclosure of which is incorporated herein by reference in its entirety. Examples of EP mapping catheters are described in the following: U.S. Patent No. 9,907,480, entitled “Catheter Spine Assembly with Closely-Spaced Bipolar Microelectrodes,” issued on March 6, 2018, the disclosure of which is incorporated herein by reference in its entirety; U.S. Publication No. 2018 / 0036078, entitled “Catheter with Bipolar Electrode Spacer and Related Methods,” published on February 8, 2018, the disclosure of which is incorporated herein by reference in its entirety; and U.S. Publication No. 2018 / 0056038, entitled “Catheter with Bipolar Electrode Spacerand Related Methods,” published on March 1, 2018, the disclosure of which is incorporated herein by reference in its entirety.

[0003] In addition to using EP mapping, some catheter ablation procedures may be performed using an image-guided surgery (IGS) system. An IGS system may enable a physician to visually track the position of a catheter in a patient relative to an image of the patient's internal anatomy in real time. Some systems may offer a combination of EP mapping and IGS capabilities, including the CARTO 3 by Biosense Webster, Inc., Irvine, California. ® Examples of catheters configured for use with the IGS system are disclosed in: U.S. Patent No. 9,480,416, entitled “Signal Transmission Using Catheter Braid Wires,” issued on November 1, 2016, the disclosure of which is incorporated herein by reference in its entirety; and various other references cited herein.

[0004] While several catheter systems and methods have been made and used, it is believed that no one prior to the inventors has made or used the invention described in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The following drawings and detailed description are merely illustrative and are not intended to limit the scope of the invention as contemplated by the inventors.

[0006] Figure 1 depicts a top view of an exemplary mapping catheter assembly;

[0007] Figure 2 Depicts the Figure 1 The line 2-2 is intercepted Figure 1 a cross-sectional end view of a mapping catheter assembly;

[0008] Figure 3 Depicted along Figure 1 The line 3-3 is intercepted Figure 1 a cross-sectional end view of a mapping catheter assembly;

[0009] Figure 4 Depicted Figure 1 a perspective partial cross-sectional view of a distal portion of a mapping catheter assembly;

[0010] Figure 5 Depicted Figure 1 A perspective view of an end effector of a mapping catheter assembly, wherein a portion of the catheter sheath is cut away to reveal the internal structure;

[0011] Figure 6 Depicted Figure 5 An enlarged perspective view of an electrode assembly of an end effector;

[0012] Figure 7 Depicted Figure 5 An exploded view of an electrode assembly of an end effector;

[0013] Figure 8 Depicts the contact tissue surface Figure 5 A side view schematic diagram of an end effector;

[0014] Fig. 9 Describes the combination Figure 5 A partial perspective view of another exemplary electrode assembly in an end effector of;

[0015] Fig.10 Depicts the bonding of contact tissue surfaces Fig. 9 The electrode assembly Figure 5 A schematic side view of the end effector;

[0016] Fig.11 Describes the combination Figure 1 A side elevation view of another exemplary end effector in a mapping catheter assembly;

[0017] Fig.12 Describes the combination Figure 1 A side elevation view of another exemplary end effector in a mapping catheter assembly;

[0018] Fig.13A Describes the combination Figure 1 Schematic diagram of a pair of linear electrodes in an end effector of a mapping catheter assembly;

[0019] Fig. 13B Describes the combination Figure 1 A schematic plan view of a pair of curved electrodes in an end effector of a mapping catheter assembly;

[0020] Fig. 13C Describes the combination Figure 1 A schematic plan view of another example of an electrode configuration in an end effector of a mapping catheter assembly;

[0021] Fig.13D Describes the combination Figure 1 A schematic plan view of another example of an electrode configuration in an end effector of a mapping catheter assembly;

[0022] Fig.14 depicts a graph showing a separated electrocardiogram signal; and

[0023] Fig.15 A curve of an electrocardiogram signal without separation is depicted. DETAILED DESCRIPTION

[0024] The following description of certain embodiments of the present invention should not be used to limit the scope of the present invention. The accompanying drawings, which are not necessarily drawn to scale, depict selected embodiments and are not intended to limit the scope of the present invention. The detailed description illustrates the principles of the present invention by way of example and not limitation. Other examples, features, aspects, embodiments and advantages of the present invention will become apparent to those skilled in the art from the following description, which, as an example, is one of the best modes for implementing the present invention. As will be appreciated, the present invention can have other different or equivalent aspects, all of which do not depart from the present invention. Therefore, the drawings and descriptions should be considered illustrative in nature, rather than restrictive.

[0025] Any one or more of the teachings, expressions, versions, examples, etc. described herein may be combined with any one or more other teachings, expressions, versions, examples, etc. described herein. Therefore, the teachings, expressions, versions, examples, etc. described below should not be viewed in isolation from each other. In view of the teachings herein, various suitable ways in which the teachings herein can be combined will be apparent to those skilled in the art. Such modifications and variations are intended to be included within the scope of the claims.

[0026] As used herein, the terms "about" or "approximately" for any numerical values ​​or ranges indicate a suitable dimensional tolerance that allows a collection of parts or components to be used for the intended purpose as described herein. More specifically, "about" or "approximately" can refer to a range of ±10% of the stated value, for example, "approximately 90%" can refer to a range from 81% to 99%. In addition, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject, and are not intended to limit systems or methods to human use, although use of the present invention in human patients represents a preferred embodiment.

[0027] I. Exemplary Mapping Catheter Assembly

[0028] A. Overview

[0029] Figure 1An exemplary mapping catheter assembly (2) is shown that can be used to provide EP mapping within the heart or other cardiovascular anatomical structure in a patient. The catheter assembly (2) of the example includes a control handle (16) and a catheter (10) extending distally from the control handle (16). The catheter (10) includes a proximal portion (12) and a distal deflection portion (14), which is laterally deflectable relative to the proximal portion (12) in response to actuation of a deflection control knob (11) of the control handle (16), which will be described in more detail below. An end effector (15) is positioned at the distal end of the catheter (10). As will be described in more detail below, the end effector (15) includes a plurality of ridges (42) having respective free ends, each ridge carrying at least one pair of closely spaced bipolar microelectrodes (85) configured to pick up electrocardiogram signals from tissue.

[0030] In this example, the proximal portion (12) of the catheter (10) is flexible but substantially incompressible along its length. Figure 2 As shown, the proximal portion (12) of the catheter (10) includes an outer wall (17) coaxially positioned around a reinforcing tube (20). By way of example only, the outer diameter of the proximal portion (12) can be less than approximately 8 French. The reinforcing tube (20) and the outer wall (17) are configured together to provide considerable torsional stability while also providing minimal wall thickness. Due to the torsional stability provided by the reinforcing tube (20) and the outer wall (17), when the control handle (16) is rotated, the deflection portion (14) and the end effector (15) of the catheter (10) will rotate in a corresponding manner. In some variations, the reinforcing tube (20) is omitted. The lumen (18) extends through the interior of the reinforcing tube (20). The lumen (18) is sized to accommodate various components, including, for example, one or more pull wires, electrode leads, irrigation tubing, and any other wires and / or cables as described below.

[0031] like Figure 3 As shown, the deflection portion (14) of the catheter (10) includes a body (19) defining a central lumen (23) and a plurality of off-axis lumens (21, 22, 24, 25) sized to accommodate various components as described below. In this example, the body (19) is formed of a more flexible material than the proximal portion (12) of the catheter (10). In this example, a set of leads (30) are contained in a non-conductive sheath (60) and extend through the length of the catheter (10). As shown in FIG. Figure 2-3As shown, the lead wire (30) and sheath (60) are positioned in the lumens (18, 21). The lead wire (30) is coupled to the microelectrode (85), as will be described in more detail below. A set of pull wires (32A, 32B) are contained in corresponding sheaths (39) and extend through the length of the catheter (10). The pull wires (32A, 32B) are positioned in the lumen (18) and the corresponding lumen (22, 24); and are offset from each other by 180 degrees in this example. The pull wires (32A, 32B) are operable to provide bidirectional lateral deflection of the deflection portion (14), as will be described in more detail below. The guide wire tube (38) also extends through the length of the catheter (10) and is positioned in the lumen (18, 23). The guidewire tube (38) is configured to slidably receive a conventional guidewire (not shown) that can be used to assist in guiding the catheter (10) in a variety of ways, as will be apparent to those skilled in the art in view of the teachings herein. A sensor cable (34) also extends through the length of the catheter (10) and is positioned within the lumen (18, 25). The sensor cable (34) is coupled to an electromagnetic position sensor (36), as will be described in more detail below.

[0032] like Figure 4 As shown, a mounting rod (46) extends between the deflection portion (14) and the end effector (15). The rod (46) is in the form of a short tubular piece mounted on the distal end of the tubular body (19). The rod (46) has a central lumen (48) to accommodate various components, including a position sensor (36) and a distal anchor for a pull wire (32A, 32B). In this example, the distal anchor includes a pair of washers (50D, 50P), each of which has a plurality of through holes (52, 54) that allow components to pass between the deflection portion (14) and the rod (46). The through holes (52, 54) are axially aligned with the lumens (22, 24) of the tubular body (19) to receive the distal ends of the pull wires (32A, 32B), respectively. By applying tension to the gasket (50D, 50P) by the pull wire (32A, 32B), the gasket (50D, 50P) is firmly and fixedly abutted against the distal end of the tubular body (19) of the deflection portion (14). Each gasket (50D, 50P) includes a through hole (51) axially aligned with the lumen (21) and allowing the lead wire (30) to pass from the deflection portion (14) and enter the lumen (48). Each gasket (50D, 50P) also includes a through hole (55) axially aligned with the lumen (25) and allowing the sensor cable (34) to pass through and enter the lumen (48) accommodating the position sensor (36). Each gasket (50D, 50P) also includes an axial through hole (53) axially aligned with the lumen (23) and allowing the guide wire tube (38) to pass through and enter the lumen (48).

[0033] like Figure 3-4As shown, pull wires (32A, 32B) are provided for bidirectional deflection of the deflection portion (14). The pull wires (32A, 32B) are actuated by a mechanism in the control handle (16) that responds to the thumb control knob or the deflection control knob (11) (see Figure 1 ). By way of example only, such deflection control may be provided in accordance with the teachings of any one or more of the following: U.S. Patent Nos. 6,123,699; 6,171,277; 6,183,435; 6,183,463; 6,198,974; 6,210,407; and 6,267,746.

[0034] B. Exemplary Multi-Ray End Effector

[0035] like Figure 1 and 4 -9, the end effector (15) of the mapping catheter assembly (2) includes a set of annular electrodes (27) and a plurality of ridges (42) positioned at the distal end of the catheter (10), each ridge carrying at least one pair of closely spaced bipolar microelectrodes (85). In this example, a pair of microelectrodes (85) are separated by a space gap distance of no more than about 200 microns. In this example, at least one pair of closely spaced bipolar microelectrodes (85) is disposed on each ridge (42). More particularly, in this example, each ridge (42) carries four pairs of bipolar microelectrodes (85), with a total of eight microelectrodes (85) per ridge (42). This number can vary as needed. By way of example only, the end effector (15) can include two to eight ridges (42); or more ridges (42) can be provided as needed. Although the ridges (42) shown have corresponding free ends, other forms can have at least one free end of a ridge connected to another free end of another ridge using a continuous member.

[0036] like Figure 4-6 As shown, each ridge (42) has a support member (43) and a non-conductive covering (44) extending along each ridge (42). The proximal portion of each ridge (42) extends proximally into the lumen (48) of the rod (46). The ridges (42) are evenly arranged around the distal opening of the rod (46) at equal angular distances from each other. An adhesive (not shown) seals the distal end of the rod (46) around the proximal portion of the ridge (42); while keeping the distal end of the guidewire tube (38) open. In this example, each ridge support member (43) is made of a material with shape memory (e.g., Nitinol, etc.). The non-conductive covering (44) can be made of any suitable material, such as a compatible plastic (e.g., polyurethane or PEBAX).

[0037] Leads (30) for microelectrodes (85) carried on the spine (42) extend through two sections (12, 14) of the catheter (10) protected by a non-conductive sheath (60). Figure 4 As shown, the leads (30) extend through a polytube (68) toward the end effector (15). The leads (30) bifurcate at the distal end of the polytube (68) and extend toward their respective spines (42). Figure 4 Only one spine (42) is shown in FIG. 4 , but the multitube (68) may be suitably sized to receive the proximal ends of all of the spines (42).

[0038] like Figure 5 and Figure 6 As shown, each ridge (42) includes a flexible microelectrode member in the form of a panel (80) fixed to the outer surface of the ridge (42) and conforming to the shape of the ridge (42). Figure 7 As shown, the panel (80) includes a biocompatible flexible plastic substrate (81) having at least a pair of closely spaced microelectrodes (85) separated by a non-conductive gap space (Lg). In some versions, the substrate (81) is generally elongated, having a thinner (T) portion (82), at least one distal wider portion (83) that crosses the longitudinal portion (82) at a generally perpendicular angle, and a proximal base portion (84a) or (84c) having a transverse dimension slightly larger than the longitudinal portion (82). The longitudinal portion (82) is configured to extend along the length of the spine (42), and the transverse portions (83a, 83b, 83c) are configured to wrap circumferentially around the distal portion of the spine (42) ( Figure 5 R in the figure). The base portion (84a, 84c) is positioned on the proximal portion of the spine (42) and is therefore protected within the lumen (48). On the base portion (84c) is a brazing patch (88), one brazing patch for each lead (30) having its distal end brazed to a corresponding brazing patch (88). Thus, the brazing patch (88) is protected and insulated within the lumen (48).

[0039] like Figure 6 As shown, microelectrodes (85) (microelectrode strips) are fixed or otherwise arranged on the outer surface of each transverse portion (83) in alignment with the transverse portion (83) so that when the transverse portion (83) is wrapped circumferentially around the spine (42), each microelectrode (85) generally forms a ring-shaped microelectrode (R). The longitudinal portion (82) can be as wide as the transverse portion (83), although the surface area coverage or thickness of the substrate will affect the flexibility of the spine (42). The microelectrode (85) can be made of any suitable solid conductive material (such as platinum or gold), or a combination of platinum and iridium. Some versions of the microelectrode (85) are coated with iridium oxide or plasma treated to improve the signal-to-noise characteristics of the microelectrode.

[0040] In some versions, the spatial gap distance (Lg) separating each microelectrode (85) in a pair is in a range from about 50 to about 300 microns. In some versions, the spatial gap distance (Lg) separating each microelectrode (85) in a pair is in a range from about 100 to about 200 microns. In some versions, the spatial gap distance (Lg) between each microelectrode (85) in a pair is about 50 microns. In addition, in some versions, each microelectrode (85) itself can have a width (W) ranging from about 50 microns to about 100 microns. In some versions, the panel (80) has a length of about 8.0 centimeters, wherein the longitudinal portion (82) has a length of about 5.0 centimeters and a width of no more than about 1.0 millimeters; each pair of microelectrodes (85) is spaced apart from an adjacent pair of microelectrodes (85) by a distance of about 5.0 millimeters, wherein each microelectrode (85) has a width of about 50 microns and a length of about 2.56 millimeters. Other suitable sizes and arrangements will be described in more detail below.

[0041] like Figure 7 As shown, the substrate (81) of this example is formed by a first or outer layer (81a), a second or middle layer (81b) and a third or inner layer (81c), each having a first surface (91) defined by surfaces (91c, 91b, 91c) and a second surface (92) defined by surfaces (92a, 92b, 92c) extending along the longitudinal axis LL. It should be understood that the letters "a", "b" and "c" represent corresponding features in the layers (81a, 81b, 81c) of the substrate (81). Microelectrodes (85) are applied or otherwise deposited on a first surface (91a) of the outer layer (81a) to cover through-holes (86a) formed in the layer (81a) to provide a connection path for electrical traces (87b) extending along the first surface (91b) of the longitudinal portion (82b) of the second layer (81b) between corresponding microelectrodes (85) and solder pads (88) carried on the second surface (92c) of the base portion (84c) of the third layer (81c). Additional traces (87c) extend along the first surface (91c) of the third layer (81c). Through-holes (86b, 89b, 89c) are formed in the layers (81b, 81c) to provide electrical traces (87b, 87c) to more proximal microelectrodes (85) and more proximal solder pads ( Figure 7 A connecting path (not shown) is provided.

[0042] In this example, the substrate (81) has three layers, each layer (81a, 81b, 81c) carrying four traces (87). It should be understood that in this example, each microelectrode (85) has a corresponding trace (87) and a corresponding solder pad (88). Each lead (30) is soldered to a corresponding solder pad (88). In this regard, it should also be understood that the traces (87) can be arranged in different ways, in different patterns and / or on different layers (81) as needed or appropriate. Adjacent microelectrodes (85) are separated by a space (Lg), and each microelectrode (85) can have a width (W) having the width previously mentioned and being greater than or equal to 0. Fig.13A Dimensions defined later in .

[0043] like Figure 5 and Figure 6 As shown, a substrate (81) is secured to a non-conductive cover (44) of a spine (42), wherein a longitudinal portion (82) extends longitudinally along the spine (42) and a transverse portion (83) wraps circumferentially around the spine (42). In this regard, the transverse dimension or width (W) of the transverse portion (83) and more importantly the microelectrode (85) relative to the longitudinal axis LL is comparable to the circumference of the spine (42), so that the opposite ends (85E) of the microelectrode (85) can contact or at least closely contact each other to generally form and function as a ring-shaped microelectrode (R) carried on the spine (42). In this example, the substrate (81) is secured to the forward facing side or distal side of the spine (42) adapted to contact tissue.

[0044] like Figure 5 As shown, each ridge (42) is preformed with a slight inward curvature so that the end effector (15) has a generally slightly concave configuration similar to an open umbrella. Figure 8 As shown, this pre-formed configuration enables each ridge (42) to engage tissue surface (93) along substantially its entire length when end effector (15) is advanced distally against tissue surface (93).

[0045] Figure 9-10 Components of another exemplary multi-ray end effector (117) are shown that may be incorporated into a mapping catheter assembly (2) in place of the end effector (15), wherein each ridge (142) defines a longitudinal axis LL. Alternatively, the end effector (117) may be incorporated into various other types of mapping catheter assemblies. The end effector (117) of this example includes a plurality of ridges (142) on which pairs of microelectrodes (185) are mounted. Although Figure 6 The ridge (42) has a more circular cross-section, but Fig. 9The ridges (142) have a more rectangular cross-section, which provides a larger planar surface (100) on which the flexible microelectrode member in the form of a panel (180) can be selectively applied or affixed. Advantageously, the entire microelectrode (185), including their ends (180E), is confined to the surface area of ​​the planar surface (100). Thus, the ridges (142) have microelectrodes (185) on only one side of each ridge (142), i.e., the tissue contacting side of each ridge (142). Thus, as Fig.10 As shown, when the planar surface (100) is in contact with the tissue (193), substantially the entire microelectrode (185) is in contact with the tissue (193). Fig. 9 As shown, a ridge (142) having a rectangular cross-section, wherein the X dimension along the planar surface (100) and transverse to the LL axis is greater than the Y dimension perpendicular to the X dimension, can help minimize kinking and stress in the ridge (142) in the region of maximum bending or divergence (D) of the ridge (142) (see Fig.10 ).

[0046] The support member (143) has a rectangular cross-section, which is adopted by the heat shrink non-conductive cover (144) to provide a larger planar surface (100). In this example, the substrate (181) of the panel (180) includes multiple layers (181a, 181b, 181c). However, the substrate (181) has no lateral portions, and the lateral dimensions (W) of the longitudinal portions are comparable to or at least not greater than the lateral dimensions of the planar surface (100), so that the substrate (181) remains constrained on the planar surface (100). The microelectrode (185) is slender and thin, and in this example is rectangular. The microelectrode (185) can be made of any suitable solid conductive material, such as platinum or gold, or a combination of platinum and iridium. Some versions of the microelectrode (185) are coated with iridium oxide or plasma treated.

[0047] As described above, the end effector (15) includes a position sensor (36). The position sensor (36) is operable to generate a signal indicating the position and orientation of the end effector (15) within the patient's body. In some versions, the position sensor (36) includes a wire coil or multiple wire coils (e.g., three orthogonal wire coils) configured to generate an electrical signal in response to the presence of an alternating electromagnetic field generated by a field generator positioned near the patient. Such position sensing capability can be provided in accordance with the teachings of any of the various patent references cited herein. The end effector (117) may also include a position sensor (36) or a variation thereof. Other components and techniques that can be used to generate real-time position data associated with the end effector (15, 117) may include wireless triangulation, acoustic tracking, optical tracking, inertial tracking, etc. Alternatively, the position sensing capability may be omitted from the end effector (15, 117).

[0048] In an exemplary use, the catheter (10) can be inserted into the patient's cardiovascular system (e.g., via a femoral artery, etc.), wherein the deflection control knob (11) and the deflection portion (14) are used to manipulate the end effector (15, 117) to a desired position (e.g., within or near a pulmonary vein, etc.). In some versions, an outer sheath (not shown) can be positioned around the end effector (15, 117) to limit the ridge (42) as the end effector (15, 117) is advanced to the target position. In such a version, the outer sheath can be retracted after the end effector (15, 117) reaches or approaches the target position. Such positioning can be performed with the assistance of an image-guided surgical system that communicates with the position sensor (36) using known techniques. Once the end effector (15, 117) reaches the target position, the microelectrodes (85, 185) can be placed in contact with the cardiovascular tissue to obtain an electrocardiogram signal. The multi-ray configuration of the end effector (15, 117) can enable simultaneous pickup of several electrocardiogram signals from different anatomical regions within the cardiovascular space. These electrocardiogram signals can be used to provide EP mapping to precisely locate the location of abnormally conducting tissue sites that cause arrhythmias. Once these abnormally conducting tissue sites are identified, the EP mapping data can be used to guide an ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0049] C. Exemplary Basket End Effector

[0050] Fig.11Another exemplary end effector (200) is shown that can be incorporated into a mapping catheter assembly (2) in place of the end effector (15). Alternatively, the end effector (200) can be incorporated into various other types of mapping catheter assemblies. The end effector (200) of this example includes an expandable assembly (220) formed by an array of beams (222) spaced apart at an angle. Each beam (222) includes four pairs (230) of bipolar microelectrodes (232, 234). The microelectrodes (232, 234) are each generally rectangular and are configured to pick up electrocardiogram signals from tissue, just like the microelectrodes (85, 185) described above. The microelectrodes (232, 234) can be made of any suitable solid conductive material, such as platinum or gold, or a combination of platinum and iridium. Some versions of the microelectrodes (232, 234) are coated with iridium oxide or plasma treated. In this example, the entirety of each microelectrode (232, 234) is confined to the outwardly presented surface of each beam (222). Thus, the beams (222) have microelectrodes (232, 234) on only one side of each beam (222), i.e., the tissue contacting side of each beam (222). Unless otherwise described herein, the various features of the end effector (200) may be configured and operable like the end effectors (15, 117) described above.

[0051] The proximal end of the beam (222) is positioned within the outer shaft (210), which can be considered similar to the mounting rod (46) described above. The distal end of the beam (222) is coupled to the hub member (212). In some versions, the hub member (212) is fixed to a central inner shaft (216) that is coaxially positioned at the center of the expandable assembly (220). The beam (222) is configured to transition the expandable assembly (220) between a non-expanded state and an expanded state. The expanded state is as shown in FIG. Fig.11 As shown. When the expandable assembly (220) is in a non-expanded state, the beams (222) are urged inwardly to define an effective outer diameter that is less than or equal to the inner diameter of the outer shaft (210). In some versions, the beams (222) are resiliently biased to provide the expandable assembly (220) in an expanded state. In some such versions, the outer sheath (214) is slidably disposed around the outer shaft (210). When the sheath (214) is in a distal position (e.g., such that the distal end of the sheath (214) is distal to the hub member (212)), the sheath (214) restrains the beams (222) inwardly, thereby maintaining the expandable assembly (220) in the non-expanded state. When the sheath (214) is in a proximal position (e.g., such as Fig.11 As shown, such that the distal end of the sheath (214) is proximal to the expandable assembly (220), the beam (222) can resiliently provide the expandable assembly (220) in the expanded state. In versions where the beam (222) is resiliently biased to provide the expandable assembly (220) in the expanded state, the inner shaft (216) can be omitted.

[0052] As another merely illustrative alternative, the state of the expandable assembly (220) can be based on the relative longitudinal positioning of the inner shaft (216) and the outer shaft (210). In versions where the inner shaft (216) is longitudinally stationary relative to the control handle (16), an actuator on the control handle (16) can drive the outer shaft (210) proximally relative to the inner shaft (216) to push the expandable assembly (220) to a non-expanded state; and drive the outer shaft (210) distally relative to the inner shaft (216) to push the expandable assembly (220) to an expanded state. In versions where the outer shaft (210) is longitudinally stationary relative to the control handle (16), an actuator on the control handle (16) can drive the inner shaft (216) distally relative to the outer shaft (210) to push the expandable assembly (220) to a non-expanded state; and drive the inner shaft (216) proximally relative to the inner shaft (210) to push the expandable assembly (220) to an expanded state. Various suitable forms of input may be provided on control handle (16) to provide such actuation, as well as various suitable ways in which expandable assembly (220) may be transitioned between the non-expanded and expanded states, will be apparent to those skilled in the art in view of the teachings herein.

[0053] In an exemplary use, the catheter (10) can be inserted into the patient's cardiovascular system (e.g., via the femoral artery, etc.), wherein the deflection control knob (11) and the deflection portion (14) are used to manipulate the end effector (200) to a desired position (e.g., within or near a pulmonary vein, etc.). According to the teachings herein, when the end effector (200) is advanced to the target position, the expandable assembly (220) can remain in a non-expanded state. After the end effector (200) reaches or approaches the target position, the expandable assembly (220) can be transformed into an expanded state according to the teachings herein. In a version in which the end effector (200) includes a position sensor similar to the position sensor (36), the positioning of the end effector (200) can be performed with the assistance of an image-guided surgery system that communicates with the position sensor. Once the end effector (200) reaches the target position, the microelectrodes (232, 234) can be placed in contact with the cardiovascular tissue to obtain an electrocardiogram signal. The basket-shaped configuration of the end effector (200) can allow various electrode pairs (230) to contact various areas of tissue simultaneously, thereby enabling the end effector (200) to simultaneously pick up several electrocardiogram signals from various anatomical regions within the cardiovascular space. These electrocardiogram signals can be used to provide EP mapping to thereby accurately locate the location of abnormally conducting tissue sites that cause arrhythmias. Once these abnormally conducting tissue sites are identified, the EP mapping data can be used to guide an ablation catheter to ablate the tissue to thereby treat the arrhythmia.

[0054] D. Exemplary Balloon End Effector

[0055] Fig.12 Another exemplary end effector (300) is shown, which can be incorporated into a mapping catheter assembly (2) in place of the end effector (15). Alternatively, the end effector (300) can be incorporated into various other types of mapping catheter assemblies. The end effector (300) of this example includes an expandable assembly (320) formed by an expandable balloon (324) to which a plurality of flexible circuits (322) are secured. The flexible circuits (322) are positioned angularly spaced around the balloon (324). Each flexible circuit (322) includes a flexible substrate (326) having four pairs (330) of bipolar microelectrodes (332, 334). The microelectrodes (332, 334) are each generally rectangular and are configured to pick up electrocardiogram signals from tissue, just like the microelectrodes (85, 185) described above. The microelectrodes (332, 334) can be made of any suitable solid conductive material, such as platinum or gold, or a combination of platinum and iridium. Some versions of the microelectrodes (332, 334) are coated with iridium oxide or plasma treated. In this example, the entirety of each microelectrode (332, 334) is confined to the outwardly presented surface of each flexible substrate (326). Thus, the flexible substrates (326) have microelectrodes (332, 334) on only one side of each flexible substrate (326), i.e., the tissue contacting side of each flexible substrate (326). Unless otherwise described herein, the various features of the end effector (300) can be configured and operated like the end effectors (15, 117) described above.

[0056] The proximal end of the flexible circuit (322) terminates distally of the proximal end of the balloon (324). The distal end of the flexible circuit (322) is connected at a hub (312), which is positioned at the distal end of the balloon (324). The balloon (324) is positioned at the distal end of the outer shaft (310), which can be considered similar to the mounting rod (46) described above. The balloon (324) is in fluid communication with a source of inflation fluid (e.g., saline, etc.) such that the inflation fluid can be driven into the balloon (324) to transform the balloon (324) into an inflated state, thereby providing the expandable assembly (320) in an expanded state (e.g., Fig.12 Inflation fluid may be withdrawn from balloon (324) to transition balloon (324) from an inflated state to a non-inflated state, thereby transitioning expandable assembly (320) to a non-expanded state. In some versions, a central shaft (not shown) is positioned within balloon (324) to maintain a consistent spacing between hub (312) and the distal end of outer shaft (310), regardless of whether expandable assembly (320) is in an expanded or non-expanded state. Various suitable ways in which balloon (324) may be inflated and deflated will be apparent to those of skill in the art in view of the teachings herein.

[0057] In an exemplary use, the catheter (10) can be inserted into the patient's cardiovascular system (e.g., through the femoral artery, etc.), wherein the deflection control knob (11) and the deflection portion (14) are used to manipulate the end effector (300) to a desired position (e.g., within or near a pulmonary vein, etc.). According to the teachings herein, when the end effector (300) is advanced to the target position, the expandable assembly (300) can be maintained in a non-expanded state. After the end effector (300) reaches or approaches the target position, the expandable assembly (320) can be transformed into an expanded state according to the teachings herein. In a version in which the end effector (300) includes a position sensor similar to the position sensor (36), the positioning of the end effector (300) can be performed with the assistance of an image-guided surgery system that communicates with the position sensor. Once the end effector (300) reaches the target position, the microelectrodes (332, 334) can be placed in contact with the cardiovascular tissue to obtain an electrocardiogram signal. The spherical configuration of the end effector (300) can enable various electrode pairs (330) to contact various areas of tissue simultaneously, thereby enabling the end effector (300) to simultaneously pick up several electrocardiogram signals from various anatomical regions within the cardiovascular space. These electrocardiogram signals can be used to provide EP mapping to thereby accurately locate the location of abnormally conducting tissue sites that cause arrhythmias. Once these abnormally conducting tissue sites are identified, the EP mapping data can be used to guide the ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0058] II. Exemplary Microelectrode Configurations for Mapping Catheter End Effectors

[0059] In some conventional EP mapping instruments (such as conventional mapping catheters with electrodes known in the art), the electrocardiogram signals picked up by the electrodes may include a large amount of far-field signals (if not most of them generated from cardiovascular structures that are not the specific structures targeted by the microelectrodes). For example, a physician may place the microelectrodes in contact with tissue in the heart (such as, for example, the pulmonary veins) to detect electrocardiogram signals at a site in the heart. In some such cases, the atria of the patient's heart may be generating electrocardiogram signals with amplitudes greater than the amplitude of the site (e.g., the pulmonary veins), and those electrocardiogram signals may be picked up by the microelectrodes at the pulmonary veins as far-field signals. Other areas of cardiac tissue may also transmit far-field signals, which are picked up by the microelectrodes at the pulmonary veins (or microelectrodes placed elsewhere in the cardiovascular space, at a distance from the cardiac tissue that generates the far-field signals). These far-field signals are added to the near-field components, and can ultimately produce an electrocardiogram signal that is artificially complex and separated, and therefore difficult to interpret.

[0060] Fig.14A graph (500) is shown of three electrocardiogram curves (502, 504, 506) from a subject with atrial fibrillation, which are separated due to the fibrillary nature of the signals as well as the far-field signals. One skilled in the art will appreciate that the curves (502, 504, 506) show the voltages sensed over time by microelectrodes contacting tissue. By way of example only, the curves (502, 504, 506) may represent electrocardiogram signals picked up by three different pairs of microelectrodes positioned within the patient's heart. To the extent that a physician is examining the electrocardiogram signals in order to identify a specific location within a pulmonary vein or any portion of cardiac tissue where an abnormal electrical signal is generated (thereby identifying a target location for ablation or other treatment), the separation shown in the curves (502, 504, 506) may make it very difficult to identify and correctly annotate the timing and rhythm of the polarization / depolarization cycles occurring within the tissue. In other words, the physician may have difficulty distinguishing between relatively small, proximal electrical potentials (e.g., from local tissue) and more distant electrical potentials. These are key aspects of electrophysiology ablation procedures, since the goal of ablation is based on analysis of electrical signals recorded by the catheter. The inventors have designed the microelectrodes described and illustrated in this article to provide an electrocardiogram signal that is substantially free of signal separation common in the fibrillary matrix of atrial fibrils of a patient. This special type of signal separation should not be confused with noise generated by electronic devices (e.g., equipment in an operating room, mobile phones, Wi-Fi signals, etc.) outside the patient. The signal separation addressed herein is due to the signal generated in the patient's heart tissue, rather than noise or other electrical signals generated by an artificial instrument or device located inside or outside the patient. In fact, even if the patient is placed in an environment without noise or other electrical signals generated by an artificial instrument or device located inside or outside the patient, this separation can be found in the electrocardiogram signal.

[0061] To the extent that software or other forms of signal processing may be intended to address the problem of separation of signals generated from cardiac tissue within a patient, such software or other forms of signal processing may be considered unreliable by physicians. Therefore, the inventors have designed an electrode-based solution to obtain an electrocardiogram signal that is substantially free of separation caused by atrial fibrillation and also free of separation caused by the interaction of complex wavefronts in the fibrous matrix of a patient with persistent AF. A variety of mechanisms have been identified or suspected to produce separated electrical signals. This includes wavefront collisions, anisotropy, fibrosis, pivoting waves, etc. ... Regardless of the mechanism, the vast majority of separations are due to the signals sensed by the electrodes exceeding the tissue they are in direct contact with. The following describes some examples of microelectrode configurations and arrangements that can provide electrocardiogram signals that are substantially free of separation caused by far-field signals generated within the patient's cardiovascular system, without the need for additional software or other signal processing solutions that are intended to reduce separation caused by far-field signals generated within the patient's cardiovascular system.

[0062] The following description relates to various arrangements and configurations of microelectrodes (85, 185, 232, 234, 332, 334) that can be used with any of the end effectors (15, 117, 200, 300) described herein. For the purpose of simplicity, and with reference to FIG. 13, the microelectrodes (85, 185, 232, 234, 332, 334) will be collectively referred to below as a pair (400) of microelectrodes (402, 404). The following teachings should be understood to be applicable to all of the microelectrode (85, 185, 232, 234, 332, 334) pairs (220, 320) described above. Those skilled in the art should also recognize that the following teachings can be readily applied to various other types of electrodes in various other types of instruments, such that the following teachings need not be limited to the microelectrodes (85, 185, 232, 234, 332, 334) described above.

[0063] Fig.13A Microelectrodes (402, 404) are shown, each having a width (W) and a length (L), wherein a gap (Lg) separates the microelectrodes (402, 404). In this example, the width (W) of the microelectrode (402) is equal to the width (W) of the microelectrode (404); and the length (L) of the microelectrode (402) is equal to the length (L) of the microelectrode (404). Therefore, in this example, both microelectrodes (402, 404) have the same surface area (l*w). The microelectrodes (402, 404) are oriented parallel to each other such that the two nearest substantially parallel surfaces (402a, 404a) define a longitudinal axis Le-Le of the microelectrode pair, such as Fig.13A , 13C and 13D. Fig.13AIn the preferred embodiment shown, the microelectrodes (402, 404) are arranged such that the length (L) extends parallel to the longitudinal axis LL of the structure (e.g., spine (42, 142), beam (222), flexible substrate (326), etc.) to which the microelectrodes (402, 404) are mounted; and such that the width (W) extends generally parallel to the longitudinal axis Le-Le of the electrode or generally perpendicular to the longitudinal axis LL of the structure to which the microelectrodes (402, 404) are mounted. The microelectrodes (402, 404) are positioned such that the microelectrodes (402, 404) are spaced apart from one another along the length of the structure to which the microelectrodes (402, 404) are mounted, such that a gap (Lg) extends between the two nearest surfaces (402a, 404a) of the microelectrodes. For ease of nomenclature with respect to this embodiment, the gap (Lg) is also considered to be generally parallel to the longitudinal axis LL of the structure to which the microelectrodes (402, 404) are mounted. Although microelectrodes (402, 404) are rectangular in the present example, microelectrodes (402, 404) may alternatively have any other suitable shape. Various other suitable shapes will be apparent to those of ordinary skill in the art in view of the teachings herein.

[0064] The inventors have determined that any arrangement of electrodes that will reduce or virtually eliminate the separation signal without applying signal processing to the sensed signal may require that the electrode pairs conform to the following empirical rules: (1) the length (L) of the electrodes must always be at least as long as the separation gap (Lg) between the electrode pairs, and (2) the ratio of the area of ​​the separation gap (Ag) to the area of ​​one electrode (Ae) must be less than or equal to 1. In short, this can be restated as: (1) L ≥ Lg, (2) Ag / Ae ≤ 1. Various arrangements of electrode and gap configurations that can achieve reduced signal separation (without signal processing) can be seen in Table 1. In Table 1, electrodes and gaps that conform to first and second aspect ratios can reduce or virtually eliminate the separation signal without using signal processing.

[0065] Table 1

[0066] Electrode width (mm) Electrode length (mm) <![CDATA[Electrode area (Ae, unit: mm 2 ).]]> Gap length Lg (mm) <![CDATA[Clearance area (Ag, in mm 2 ).]]> First aspect ratio (L / Gg) Second aspect ratio (Ag / Ae) 0.8 0.1 0.08 0.1 0.08 1 1 0.8 0.3 0.24 0.2 0.16 1.5 0.67 0.8 0.5 0.4 0.1 0.08 5 0.2 0.8 0.5 0.4 0.2 0.16 2.5 0.4 0.8 0.5 0.4 0.5 0.4 1 1 1 0.5 0.5 0.1 0.1 5 0.2 1 0.5 0.5 0.2 0.2 2.5 0.4 1 0.5 0.5 0.5 0.5 1 1 1 1 1 0.1 0.1 10 0.1 1 1 1 0.2 0.2 5 0.2 1 1 1 0.5 0.5 2 0.5

[0067] The sensing and recording of electrocardiogram signals by the electrode configuration of the present invention is advantageous because no special signal processing other than conventional low-pass and high-pass filters (as will be apparent to one skilled in the art) needs to be applied to render an electrocardiogram having little or no separation or far-field signals. It is believed that the signal processing that reduces or eliminates far-field signals from the sensed electrocardiogram is based on certain exclusion criteria that may not be applicable to the sensed signal, and therefore the post-processed signal may not be an accurate representation of the signal generated locally by the cardiac tissue.

[0068] As further examples only, the surface area of ​​each microelectrode (402, 404) can be approximately 0.4 square millimeters or less; any surface area from approximately 0.05 square millimeters to approximately 0.4 square millimeters; any surface area from approximately 1 square millimeter to approximately 0.4 square millimeters. As used herein, the term "area" or "surface area" is the amount of a unit square (in a suitable unit of size, such as millimeters) that can be contained or fit within the two-dimensional planar boundaries of the electrode. The term "area" or "surface area" does not include any meaning associated with "surface roughness"; "surface texture"; "fractal surface area"; or any measurement related to the surface contour or fractal of such an area. Similarly, in the case where the electrode is wound or curled onto a non-planar substrate, the area (or surface area) of the electrode is the area unfolded into a two-dimensional planar shape. And in the case where the electrode includes a three-dimensional configuration, the relevant "area" or "surface area" of such an electrode is the planar surface that is in direct physical contact with the heart tissue.

[0069] As examples of linear electrodes only, the length (L) of each microelectrode (402, 404) can be any length from approximately 100 microns to approximately 1 millimeter; any length from approximately 100 microns to approximately 300 microns; any length from approximately 300 microns to approximately 500 microns; or any length from approximately 500 microns to approximately 1 millimeter.

[0070] As an example of a linear electrode only, the width (W) of each microelectrode (402, 404) may be anywhere from approximately 800 microns to approximately 1 millimeter; anywhere from approximately 800 microns to approximately 0.5 millimeters.

[0071] By way of further example only, the gap distance (Lg) of each microelectrode (402, 404) may be anywhere from approximately 50 microns to approximately 1 millimeter; anywhere from approximately 50 microns to approximately 0.5 millimeters.

[0072] In one version, such as Fig.13A As schematically shown in , each electrode of the electrode pair has a generally rectangular configuration having a dimension (width W) of about 800 microns measured along the longitudinal axis Le-Le of the microelectrode (or as measured perpendicular to the longitudinal axis LL) and a longitudinal dimension (length L) of about 300 microns measured approximately parallel to the axis LL to provide an electrode surface area of ​​about 0.24 square millimeters and a gap length (Lg) as measured between the two closest surfaces (402a, 404a) of the corresponding microelectrode. In other words, the gap length (Lg) can be considered to be approximately perpendicular to the microelectrode longitudinal axis Le-Le of about 200 microns (or approximately parallel to the longitudinal axis LL), and for a gap surface area of ​​about 160 microns, the gap width is the same as the electrode width W.

[0073] In an alternative version, Fig.13A The microelectrodes (402, 404) can be rotated about 90 degrees so that the longitudinal axis Le-Le of the microelectrode coincides with (or is parallel to) the longitudinal axis LL of the ridge (42), as shown in FIG. Fig. 13C It should be noted that the orientation of the microelectrodes is not limited to a specific angle of the longitudinal axis Le-Le relative to the longitudinal axis LL, but can be in any orientation, such as Fig.13D As shown in the electrode pair (402''', 404''') or the electrode pair (402", 404"), as long as the two closest surfaces of the corresponding microelectrode pair are substantially parallel. Fig.13D In , we have designed the electrode configuration so that the electrodes satisfy the empirical rule that the electrodes can be in any orientation (and number of electrodes) as long as at least two nearest surfaces of the corresponding microelectrodes are substantially parallel to the gap distance Lg between the substantially parallel surfaces. Specifically, for each set of electrodes, there can be at least two substantially parallel nearest surfaces that reach the gap Lg. For example, Fig.13D The top group of four electrodes (404''', 406, 402''', 408) in the embodiment of the present invention; the electrode (404''') has a surface roughly parallel to the surface of the electrode (406 or 408) to form a first pair (404''', 406) or a second pair (404''', 408), the first pair and the second pair having a gap Lg; the electrode (404''') has a surface roughly parallel to the surface of the electrode (402''') to form a third electrode pair having a gap Lg; the electrode (406) has a surface roughly parallel to the electrode (402''') to form a fourth electrode pair. About Fig.13D In the bottom electrode group, the electrode (404''') has a surface substantially parallel to the surfaces of the electrodes (406', 402''') to define a gap Lg; the electrode (406') has a corresponding surface substantially parallel to the corresponding surfaces of the electrodes (404''', 402''') to define a corresponding gap Lg.

[0074] The electrode pair configuration may be a shape other than a straight line (such as a circle ( Fig. 13B ), polygon ( Fig.13D ) or curvilinear electrodes), a conversion factor CF can be used to determine the appropriate gap distance between the electrodes based on the known planar area of ​​either of the electrode pair. The conversion factor CF can range from about 2 to 0.1 times the reciprocal of the same root dimension unit as the planar area of ​​the electrodes. In one example, where the planar area of ​​one of the electrodes is about 0.08 square millimeters, the minimum gap distance (Lg) along the longitudinal axis extending through the two electrodes can be determined by applying the conversion factor CF (in the same root dimension unit of area, or mm) to determine the appropriate gap distance between the electrodes.-1 In another example, where the area of ​​one of the electrodes is 0.24 square millimeters, giving a minimum gap distance Lg ranging from about 300 microns to about 24 microns, the conversion factor CF (in the same root dimension unit or mm) is -1 The reciprocal of -1 Regardless of the shape of the electrode, the preferred conversion factor CF is about 0.83 (in terms of the reciprocal of the same root dimension unit of the electrode area).

[0075] The configuration and arrangement of the microelectrodes (402, 404) as described above can prevent the microelectrodes (402, 404) from picking up far-field ECG signals (e.g., from the atria), so that the microelectrodes (402, 404) only pick up ECG signals generated by tissues in contact with the microelectrodes (402, 404) (e.g., the pulmonary veins). Fig.15 A graph (600) is shown of three electrocardiogram signal curves (602, 604, 606) with substantially no separation, representing signals picked up by microelectrodes (402, 404) configured and arranged in accordance with the teachings above. One skilled in the art will appreciate that the curves (602, 604, 606) show voltages varying over time as sensed by microelectrodes contacting tissue. By way of example only, the curves (602, 604, 606) may represent electrocardiogram signals picked up by three different microelectrode pairs (400) positioned within a patient's pulmonary veins. To the extent that other cardiac structures (e.g., the atria) are generating far-field signals having considerable amplitudes, these far-field signals are not picked up by the microelectrode pairs (400) due to the configuration and arrangement of the electrodes (402, 404) in each pair of electrodes (400) as described above. Instead, the curves (602, 604, 606) show only the potentials from the associated regions of the pulmonary veins themselves.

[0076] because Fig.15 These curves (602, 604, 606) do not have Fig.14 The separation of the curves (502, 504, 506) shown so that a physician can more easily annotate the timing of the wavefront and potentially be able to make a better diagnosis of the direction, source, and cycle length of the wavefront to determine the specific location within the tissue associated with the abnormal electrical signal; and thereby identify the appropriate location for treatment (e.g., ablation, etc.) with greater certainty and precision. It should be understood that Fig.15 The ECG signal relative to Fig.14 The improvement in the electrocardiogram signal is simply due to the configuration and arrangement of the electrodes (402, 404) in each pair of electrodes (400) as described above. In this example, Fig.15 The ECG signal relative to Fig.14The improvement of the ECG signal is not due to the use of signal filtering algorithms or other signal processing techniques.

[0077] III. Exemplary Combinations

[0078] The following examples relate to various non-exhaustive ways in which the teachings of this document may be combined or applied. It should be understood that the following embodiments are not intended to limit the coverage of any claims that may be filed at any time in this application or a subsequent application of this application. There is no intention to abandon. The following examples are provided for illustrative purposes only. It is conceivable that the various teachings of this document may be arranged and applied in a variety of other ways. It is also conceivable that some variations may omit certain features mentioned in the following examples. Therefore, unless the inventor or the inventor's successor in interest explicitly points out later, none of the aspects or features mentioned below should be considered critical. If any claim filed in this application or a subsequent application related to this application includes additional features in addition to the features mentioned below, these additional features should not be considered to be added for any reason related to patentability.

[0079] Example 1

[0080] A device comprising: (a) a shaft; and (b) an end effector at a distal end of the shaft, wherein the end effector is sized to fit within an anatomical passage within a cardiovascular system of a subject, wherein the end effector comprises at least one electrode pair, wherein the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, wherein each electrode pair comprises: (i) a first electrode having a first surface area in units of square dimension, and (ii) a second electrode having the first surface area, wherein the first and second electrodes are separated from each other by a gap distance, wherein the gap distance is defined by the product of the first surface area and a conversion factor, the conversion factor ranging from approximately 0.1 to approximately 2 times the inverse of the square root of the same unit of dimension as the first surface area.

[0081] Example 2

[0082] The apparatus of Example 1, wherein the end effector further comprises a plurality of elongated spines and a plurality of electrode pairs, wherein the electrode pairs are secured to the spines.

[0083] Example 3

[0084] The device of Example 2, wherein the shaft defines a longitudinal axis, wherein the spines extend outwardly away from the longitudinal axis, wherein the spines have respective free ends oriented away from the longitudinal axis.

[0085] Example 4

[0086] The device of Example 2, wherein the spines are configured to curve outward and converge distally to form a basket-like configuration.

[0087] Example 5

[0088] The apparatus of Example 2, wherein the end effector further comprises an expandable member, wherein the ridge is secured to an outer surface of the expandable member.

[0089] Example 6

[0090] The apparatus of any one or more of Examples 1-5, wherein the first surface area comprises approximately 0.95 square millimeters or less.

[0091] Example 7

[0092] The apparatus of any one or more of Examples 1-5, wherein the first surface area comprises approximately 0.4 square millimeters or less.

[0093] Example 8

[0094] The apparatus of any one or more of Examples 1-7, wherein the gap distance comprises any distance from approximately 50 microns to approximately 3 millimeters.

[0095] Example 9

[0096] The apparatus of Example 8, wherein the gap distance comprises any distance from approximately 50 microns to approximately 0.5 millimeters.

[0097] Example 10

[0098] The apparatus of any one or more of Examples 1 to 9, wherein the end effector comprises at least one electrode support member associated with the at least one electrode pair, wherein each electrode support member comprises a first side and a second side, wherein the electrode pair is present on only one side of the corresponding electrode support member.

[0099] Example 11

[0100] The device of any one or more of Examples 1-10, wherein the first and second electrodes of each electrode pair comprise a biocompatible metal or a conductive polymer.

[0101] Example 12

[0102] The device of Example 11, wherein the biocompatible metal comprises a metal selected from platinum, palladium, cobalt chromium, nitinol, gold, or any combination thereof.

[0103] Example 13

[0104] The device of any one or more of Examples 11-12, wherein the biocompatible metal is coated with iridium oxide.

[0105] Example 14

[0106] The device of any one or more of Examples 11-13, wherein the biocompatible metal is plasma treated.

[0107] Example 15

[0108] The device of any one or more of Examples 1 to 14, wherein the at least one electrode pair is configured to pick up electrocardiographic signals of direct tissue in contact with the electrode pair without separation from far-field interactions.

[0109] Example 16

[0110] The device of any one or more of Examples 1 to 14, wherein the at least one electrode pair is configured to collect electrocardiogram signals of cardiac tissue contacted by the electrode pair, such that the electrocardiogram signals collected by the electrode pair are signals with significantly reduced separation during fibrillation of the cardiac tissue.

[0111] Example 17

[0112] The apparatus of any one or more of Examples 1-16, wherein the electrode surface area comprises any surface area from approximately 0.05 square millimeters to approximately 1 square millimeter and a gap length (Lg) from approximately 100 micrometers to approximately 500 micrometers.

[0113] Example 18

[0114] The apparatus of any one or more of Examples 1-16, wherein the first surface area comprises any surface area from approximately 0.24 square millimeters to approximately 0.4 square millimeters.

[0115] Example 19

[0116] The apparatus of any one or more of Examples 1-18, wherein the end effector is sized to fit within an anatomical passage within a human cardiovascular system.

[0117] Example 20

[0118] The device of any one or more of Examples 1 to 19, wherein the first and second electrodes are each rectangular such that the first surface area is defined by a first length of the first and second electrodes and a first width of the first and second electrodes.

[0119] Example 21

[0120] The device of Example 20, wherein the electrode pair comprises a configuration other than a rectilinear planar shape.

[0121] Example 22

[0122] The apparatus of any one or more of Examples 20-21, wherein the first length comprises any length from approximately 100 microns to approximately 750 microns.

[0123] Example 23

[0124] The apparatus of any one or more of Examples 20-21, wherein the first width comprises any width of approximately 800 microns to approximately 1 millimeter.

[0125] Example 24

[0126] The apparatus of any one or more of Examples 20-21, wherein the gap distance comprises any distance from approximately 50 microns to approximately 3 millimeters.

[0127] Example 25

[0128] The apparatus of any one or more of Examples 20-21, wherein the first width comprises any width of approximately 800 microns to approximately 0.5 millimeters.

[0129] Example 26

[0130] The device of any one or more of Examples 20 to 25, wherein the gap distance is a distance between an area of ​​up to one square millimeter of one electrode and about 1.25 mm -1 or smaller conversion factors.

[0131] Example 27

[0132] The apparatus of Example 26, wherein the conversion factor is approximately 0.83 mm -1 .

[0133] Example 28

[0134] The device of Example 26, wherein the conversion factor is about 0.2 mm -1 .

[0135] Example 29

[0136] The device of Example 26, wherein the conversion factor is about 0.4 mm in terms of the root dimension of the electrode area -1 .

[0137] Example 30

[0138] The device of Example 26, wherein the conversion factor is about 1 mm -1 .

[0139] Example 31

[0140] The device of Example 26, wherein the conversion factor is about 0.5 mm -1 .

[0141] Example 32

[0142] 14. Apparatus according to any preceding claim, wherein the longitudinal axis comprises a longitudinal axis defined by two nearest substantially parallel surfaces of the microelectrode.

[0143] Example 33

[0144] A device comprising: (a) a shaft; and (b) an end effector at a distal end of the shaft, wherein the end effector is sized to fit within an anatomical passage within a human cardiovascular system, wherein the end effector comprises at least one electrode pair, wherein the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, wherein each electrode pair comprises: (i) a first electrode having a first surface area not greater than approximately 1 square millimeter, and (ii) a second electrode having a second surface area, wherein the first and second electrodes are spaced apart from each other by a gap distance defined by two nearest substantially parallel surfaces of the respective first and second electrodes, wherein the gap distance (Lg) comprises a distance from one of the first surface area or the second surface area to not greater than approximately 1.25 mm -1 Any value of the product of the conversion factors.

[0145] Example 34

[0146] The apparatus of Example 33, wherein the second surface area is equal to the first surface area.

[0147] Example 35

[0148] The device of any one or more of Examples 33-34, wherein the first surface region comprises an area selected from approximately 0.08 square millimeters, 0.24 square millimeters, 0.4 square millimeters, 0.5 square millimeters, or 1 square millimeter.

[0149] Example 36

[0150] The apparatus of any one or more of Examples 33-35, wherein the gap distance (Lg) comprises any distance from approximately 50 microns to approximately 500 microns.

[0151] Example 37

[0152] The apparatus of any one or more of Examples 33-35, wherein the gap distance comprises any distance from approximately 100 microns to approximately 200 microns.

[0153] Example 38

[0154] The apparatus of any one or more of Examples 33-37, wherein the first and second electrodes comprise substantially the same curvilinear planar configuration.

[0155] Example 39

[0156] The apparatus of any one or more of Examples 33-37, wherein the first and second electrodes comprise substantially identical rectilinear planar configurations.

[0157] Example 40

[0158] The apparatus of any one or more of Examples 33 to 39, wherein the first width and the gap distance have a ratio of approximately 5:1.

[0159] Example 41

[0160] A device comprising: (a) a shaft; and (b) an end effector at a distal end of the shaft, wherein the end effector is sized to fit within an anatomical passage within a cardiovascular system of a subject, wherein the end effector comprises at least one electrode pair, wherein the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up electrocardiographic signals, each electrode pair comprising first and second electrodes, the first and second electrodes being spaced apart from each other along a longitudinal axis by a gap area (Ag) between the electrodes, the gap area (Ag) having a gap length (Lg) relative to the longitudinal axis such that: (i) a length (L) of one of the electrodes along the longitudinal axis is equal to or greater than the gap length; and (ii) a ratio of an area defined by the gap area (Ag) to an area of ​​one electrode (Ae) is equal to or less than 1.

[0161] Example 42

[0162] The apparatus of Example 41 is combined with any one or more of Examples 2 to 32.

[0163] IV. Multifaceted

[0164] In some versions, the end effector (15, 117, 200, 300) is configured to provide RF ablation in addition to providing EP mapping functionality. In some such versions, the end effector (15, 117, 200, 300) includes additional electrodes dedicated to providing RF ablation. Such RF ablation capability can be provided in accordance with the teachings of the various patent references cited herein. Alternatively, the RF ablation capability can be omitted from the end effector (15, 117, 200, 300).

[0165] It should be understood that any example described herein may include various other features in addition to or in place of the above features. As an example only, any example described herein may also include one or more of the various features disclosed in the various references cited herein.

[0166] It should be understood that any one or more of the teachings, expressions, embodiments, examples, etc. described herein may be combined with any one or more other teachings, expressions, embodiments, examples, etc. described herein. The above teachings, expressions, embodiments, examples, etc. should therefore not be viewed in isolation from each other. In view of the teachings herein, various suitable ways in which the teachings herein can be combined will be apparent to those skilled in the art. Such modifications and variations are intended to be included within the scope of the claims.

[0167] Various versions of the invention have been shown and described, and further modifications to the methods and systems described herein may be accomplished by appropriate modifications by those skilled in the art without departing from the scope of the invention. Several such potential modifications have been mentioned, and other modifications will be apparent to those skilled in the art. For example, the examples, versions, geometries, materials, dimensions, ratios, steps, etc. discussed above are illustrative and not required. Accordingly, the scope of the invention should be considered in light of the claims below, and should be understood not to be limited to the details of the structure and operation shown and described in the specification and drawings.

Claims

1. A device comprising: (a) axis; and (b) an end effector at a distal end of the shaft, wherein the end effector is sized to fit within an anatomical passage within a cardiovascular system of a subject, wherein the end effector comprises at least one electrode pair, wherein the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up electrocardiographic signals, each electrode pair comprising a first electrode and a second electrode, the first electrode and the second electrode being spaced apart from each other along the longitudinal axis by a gap area (Ag) between the electrodes, the gap area (Ag) having a gap distance (Lg) relative to the longitudinal axis such that: (1) the length (L) of one of the electrodes along the longitudinal axis is equal to or greater than the gap distance; and (2) the ratio of the area defined by the gap area (Ag) to the surface area of ​​one electrode (Ae) is equal to or less than 1, The gap distance consists of an electrode area of ​​up to one square millimeter and 1.25 mm -1 or smaller conversion factors.

2. The device according to claim 1, wherein The end effector also includes a plurality of elongated spines and a plurality of electrode pairs, wherein the electrode pairs are secured to the spines.

3. The device according to claim 2, wherein: The spines include respective free ends extending along the longitudinal axis.

4. The device according to claim 2, wherein: The spines are configured to curve outwardly and converge distally to form a basket-like configuration.

5. The device according to claim 2, wherein: The end effector also includes an expandable member, wherein the spine is secured to an outer surface of the expandable member.

6. The device according to any one or more of claims 1 to 5, wherein: The surface area of ​​one electrode comprises 0.95 square millimeters or less.

7. The device according to any one or more of claims 1 to 5, wherein: The surface area of ​​one electrode comprises 0.4 square millimeters or less.

8. The device according to any one or more of claims 1 to 5, wherein: The gap distance includes any distance from 50 microns to 3 millimeters.

9. The device according to claim 8, wherein: The gap distance includes any distance from 50 microns to 0.5 millimeters.

10. The device according to any one or more of claims 1 to 5, wherein: The end effector includes at least one electrode support member associated with the at least one electrode pair, wherein each electrode support member includes a first side and a second side, wherein the electrode pair is present on only one side of the corresponding electrode support member.

11. The device according to any one or more of claims 1 to 5, wherein: The first electrode and the second electrode of each electrode pair include a biocompatible metal or a conductive polymer.

12. The device according to claim 11, wherein The biocompatible metal includes a metal selected from platinum, palladium, cobalt chromium, nitinol, gold or any combination thereof.

13. The device according to claim 11, wherein: The biocompatible metal is coated with iridium oxide.

14. The device according to claim 11, wherein: The biocompatible metal is plasma treated.

15. The device according to any one or more of claims 1 to 5, wherein: The at least one electrode pair is configured to pick up electrocardiographic signals of direct tissue in contact with the electrode pair without separation from far-field interactions.

16. Apparatus according to any one or more of claims 1 to 5, wherein: The at least one electrode pair is configured to collect an electrocardiogram signal of a heart tissue contacted by the electrode pair, such that the electrocardiogram signal collected by the electrode pair is a signal with significantly reduced separation during fibrillation of the heart tissue.

17. Apparatus according to any one or more of claims 1 to 5, wherein: The one electrode surface area includes any surface area from 0.05 square millimeters to 1 square millimeter and a gap distance (Lg) from 100 micrometers to 500 micrometers.

18. Apparatus according to any one or more of claims 1 to 5, wherein: The one electrode surface area includes any surface area from 0.24 square millimeters to 1 square millimeter.

19. The device according to any one or more of claims 1 to 5, wherein: The end effector is sized to fit within an anatomical passage within the human cardiovascular system.

20. Apparatus according to any one or more of claims 1 to 5, wherein: The first and second electrodes are each rectangular, such that the one electrode surface area is defined by a first length of the first and second electrodes and a first width of the first and second electrodes.

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