Device for diagnosing arrhythmias

Abstract

To provide an EP mapping within the heart or other cardiovascular anatomical structures within a patient.SOLUTION: An apparatus includes a shaft and an end effector at a distal end of the shaft. The end effector is sized to fit in an anatomical passageway within a subject's cardiovascular system. The end effector includes at least one electrode pair that is configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals. Each electrode pair includes first and second electrodes spaced along a longitudinal axis by a gap area located between the electrodes. The gap area has a gap length with respect to the longitudinal axis. A length of one of the electrodes along the longitudinal axis is equal to or greater than the gap length. A ratio of an area defined by the gap area to one electrode area is equal to or less than one.SELECTED DRAWING: None

Description

Content of disclosure

[0001] Cardiac arrhythmias, such as atrial fibrillation, occur when areas of cardiac tissue conduct electrical signals abnormally. Treatment for arrhythmias includes surgically interrupting such signal conduction pathways. By selectively ablating cardiac tissue with the application of energy (e.g., radiofrequency (RF) energy), it may be possible to stop or correct the unwanted propagation of electrical signals from one part of the heart to another. The ablation process may provide a barrier to the unwanted electrical pathways by forming electrically insulating lesions or scar tissue.

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

[0003] In addition to the use of EP mapping, some catheter ablation procedures can be performed using image-guided surgery (IGS) systems. IGS systems can enable physicians to visually track the location of a catheter within a patient in real time in relation to images of the patient's anatomical structures. Several systems, including the CARTO 3® system by Biosense Webster, Inc. of Irvine, California, can offer a combination of EP mapping and IGS functionality. Examples of catheters configured for use with IGS systems are disclosed in U.S. Patent No. 9,480,416, “Signal Transmission Using Catheter Braid Wires,” published November 1, 2016, and in various other references cited herein, the disclosure of which is incorporated herein by reference in its entirety.

[0004] Although several catheter systems and methods have been fabricated and used, it is believed that no one has made or used the invention described in the appended claims prior to the present inventors.

[0005] The following drawings and detailed description are for illustrative purposes only and are not intended to limit the scope of the invention as intended by the inventors. [Brief explanation of the drawing]

[0006] [Figure 1] An example top view of a mapping catheter assembly is shown. [Figure 2] Figure 1 shows a cross-sectional end view of the mapping catheter assembly along line 2-2 in Figure 1. [Figure 3] Figure 1 shows a cross-sectional end view of the mapping catheter assembly along line 3-3 in Figure 1. [Figure 4] Figure 1 shows a cross-sectional view of the distal portion of the mapping catheter assembly in an oblique view. [Figure 5]Figure 1 shows a perspective view of the end effector of the mapping catheter assembly, with a portion of the catheter sheath detached to reveal the internal structure. [Figure 6] Figure 5 shows an enlarged perspective view of the electrode assembly of the end effector. [Figure 7] Figure 5 shows an exploded view of the electrode assembly of the end effector. [Figure 8] Figure 5 shows a schematic side view of the end effector that comes into contact with the tissue surface. [Figure 9] Figure 5 shows a partial perspective view of another exemplary electrode assembly that may be incorporated into the end effector. [Figure 10] Figure 5 shows a schematic side view of the end effector incorporating the electrode assembly shown in Figure 9, which comes into contact with the tissue surface. [Figure 11] Figure 1 shows a side view of another exemplary end effector that may be incorporated into the mapping catheter assembly. [Figure 12] Figure 1 shows a side view of another exemplary end effector that may be incorporated into the mapping catheter assembly. [Figure 13A] Figure 1 shows a schematic diagram of a pair of linear electrodes that can be incorporated into the end effector of the mapping catheter assembly. [Figure 13B] Figure 1 shows a schematic plan view of a pair of curved electrodes that can be incorporated into the end effector of the mapping catheter assembly. [Figure 13C] Figure 1 shows a schematic plan view of another embodiment of an electrode configuration that may be incorporated into the end effector of the mapping catheter assembly. [Figure 13D] Figure 1 shows a schematic plan view of another embodiment of an electrode configuration that may be incorporated into the end effector of the mapping catheter assembly. [Figure 14] The image shows a plot of electrocardiogram signals indicating the fractionation. [Figure 15] This shows a plot of the electrocardiogram signal without fractionation.

[0007] [Detailed explanation] The following description of specific embodiments of the present invention should not be used to limit the scope of the invention. The drawings are not necessarily to scale and illustrate selected embodiments, and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention, not limiting them. Other embodiments, features, aspects, forms, and advantages of the invention will become apparent to those skilled in the art from the following description, which, as examples, is one of the best modes intended to carry out the invention. As will be recognized, other different or equivalent embodiments are possible without departing from the invention. Therefore, the drawings and description should be considered as illustrative and not limiting in nature.

[0008] Any one or more of the teachings, expressions, versions, examples, etc., described herein may be combined with any one or more of the other teachings, expressions, versions, examples, etc., described herein. Therefore, the teachings, expressions, versions, examples, etc., described below should not be viewed in isolation. Various appropriate ways in which the teachings herein may be combined will be readily apparent to those skilled in the art, given the teachings herein. Such modifications and variations are intended to be included within the claims.

[0009] Where used herein, the terms “about” or “approximately” for any number or range indicate a suitable dimensional tolerance that enables some or all of the components to function for their intended purpose, as described herein. More specifically, “about” or “approximately” can refer to a range of values ​​within ±10% of the enumerated values; for example, “about 90%” can refer to a range of values ​​between 81% and 99%. Furthermore, where used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject, and are not intended to limit the use of the system or method to human use, although the use of the present invention in a human patient represents a preferred embodiment.

[0010] I. Exemplary Mapping Catheter Assembly A. Overview FIG. 1 shows an exemplary mapping catheter assembly (2) that can be used to provide EP mapping within the heart or other cardiovascular anatomical structures within a patient. The catheter assembly (2) of this embodiment 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), and the distal deflection portion is deflectable laterally with respect to the proximal portion (12) in response to the actuation of the deflection control knob (11) of the control handle (16), as will be described in more detail below. The end effector (15) is positioned at the distal end of the catheter (10). Also as will be described in more detail below, the end effector (15) includes a plurality of spines (42) having respective free ends, and each spine has at least a pair of closely spaced bipolar microelectrodes (85) configured to pick up electrocardiogram signals from tissue.

[0011] In this embodiment, the proximal portion (12) of the catheter (10) is flexible but substantially non-compressible along its length. As shown in FIG. 2, the proximal portion (12) of the catheter (10) includes an outer wall (17) coaxially positioned around a reinforcing tube (20). As an example only, the outer diameter of the proximal portion (12) can be less than about 8 French. The reinforcing tube (20) and the outer wall (17) are both configured to provide substantial torsional stability and also to provide a minimum wall thickness. Due to the torsional stability provided by the reinforcing tube (20) and the outer wall (17), when the control handle (16) rotates, the deflection portion (14) and the end effector (15) of the catheter (10) rotate correspondingly. In some variations, the reinforcing tube (20) is omitted. A 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 tension wires, electrode leads, irrigation tubes, and any other wires and / or cables as described below.

[0012] As shown in FIG. 3, the deflectable portion (14) of the catheter (10) includes a tube body (19) that defines 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 embodiment, the tube body (19) is formed of a material more flexible than the proximal portion (12) of the catheter (10). In this embodiment, a set of lead wires (30) is housed within a non-conductive sheath (60) and extends along the length of the catheter (10). As shown in FIGS. 2-3, the lead wires (30) and the sheath (60) are positioned within the lumens (18, 21). The lead wires (30) are connected to microelectrodes (85), as will be described in more detail below. A set of tension wires (32A, 32B) is housed within respective sheaths (39) and extends along the length of the catheter (10). The tension wires (32A, 32B) are positioned within the lumen (18) and respective lumens (22, 24); in this embodiment, they are angularly offset from each other by 180 degrees. The tension wires (32A, 32B) are operable to provide bi-directional lateral deflection of the deflectable portion (14), as will be described in more detail below. A guide wire tube (38) also extends along the length of the catheter (10) and is positioned within the lumens (18, 23). The guide wire tube (38) is configured to slidably accommodate a conventional guide wire (not shown), which can be used to assist in guiding the catheter (10) in various ways, as will be apparent to those skilled in the art in light of the teachings of this specification. A sensor cable (34) also extends along the length of the catheter (10) and is positioned within the lumens (18, 25). The sensor cable (34) is connected to an electromagnetic position sensor (36), as will be described in more detail below.

[0013] As shown in Figure 4, a mounting stem (46) extends between the deflection portion (14) and the end effector (15). The stem (46) is in the form of a short tube mounted on the distal end of the tube body (19). The stem (46) has a central lumen (48) for accommodating various components, including a distal anchor for a position sensor (36) and tension wires (32A, 32B). In this embodiment, the distal anchor includes a pair of washers (50D, 50P), each washer having multiple through-holes (52, 54) that allow components to pass between the deflection portion (14) and the stem (46). The through-holes (52, 54) are axially aligned with the lumen (22, 24) of the tube body (19), respectively, to receive the distal ends of the tension wires (32A, 32B). When tension is applied to the washers (50D, 50P) by the tension wires (32A, 32B), the washers (50D, 50P) firmly fix and contact the distal end of the tube body (19) of the deflection section (14). Each washer (50D, 50P) is aligned axially with the lumen (21) and includes a through-hole (51) through which the lead wire (30) passes from the deflection section (14) into the lumen (48). Each washer (50D, 50P) is also aligned axially with the lumen (25) and includes a through-hole (55) through which the sensor cable (34) passes into the lumen (48) in which the position sensor (36) is housed. Each washer (50D, 50P) is aligned axially with the lumen (23) and further includes an axial through-hole (53) through which the guidewire tube (38) passes into the lumen (48).

[0014] As shown in Figures 3 and 4, tension wires (32A, 32B) are provided for bidirectional deflection of the deflection portion (14). The tension wires (32A, 32B) are actuated by a mechanism in a control handle (16) that responds to a thumb control knob or a deflection control knob (11) (see Figure 1). As just one example, such deflection control may be provided in accordance with one or more teachings of U.S. Patents 6,123,699; 6,171,277; 6,183,435; 6,183,463; 6,198,974; 6,210,407 and 6,267,746.

[0015] B. Exemplary multi-lay end effectors As shown in Figures 1 and 4-9, the end effector (15) of the mapping catheter assembly (2) includes a pair of ring electrodes (27) positioned at the distal end of the catheter (10), and a plurality of spines (42), each spine having at least one pair of closely spaced bipolar microelectrodes (85). In this embodiment, the pair of microelectrodes (85) have a separation space gap distance of about 200 μm or less between them. In this embodiment, at least one pair of closely spaced bipolar microelectrodes (85) are provided on each spine (42). More specifically, in this embodiment, each spine (42) has four pairs of bipolar microelectrodes (85) for a total of eight microelectrodes (85) per spine (42). This number can be changed as needed. As just one example, the end effector (15) can include two to eight spines (42); or it can include more spines (42) as needed. Although the spines (42) are shown having their own free ends, other versions may have at least one free end of one spine connected to another free end of another spine by a continuous member.

[0016] As shown in Figures 4 to 6, each spine (42) has a support member (43) and a non-conductive coating (44) extending along each spine (42). The proximal portion of each spine (42) extends proximal into the lumen (48) of the stem (46). The spines (42) are uniformly arranged at equiangular distances from each other around the distal opening of the stem (46). An adhesive (not shown) seals the distal end of the stem (46) around the proximal portions of the spines (42); while leaving the distal end of the guidewire tube (38) open. In this embodiment, each spine support member (43) is made of a shape-memory material (e.g., nitinol). The non-conductive coating (44) can be made of any suitable material such as a biocompatible plastic (e.g., polyurethane or PEBAX).

[0017] Lead wires (30) for the microelectrode (85) held on the spine (42) extend through both portions (12, 14) of the catheter (10) and are protected by a non-conductive sheath (60). Towards the end effector (15), the lead wires (30) extend through a polytube (68), as shown in Figure 4. The lead wires (30) branch at the distal end of the polytube (68) and extend toward each spine (42). Although only one spine (42) is shown in Figure 4, the polytube (68) can be appropriately sized to accommodate the proximal ends of all spines (42).

[0018] As shown in Figures 5 and 6, each spine (42) includes a flexible microelectrode member in the form of a panel (80) fixed to the outer surface of the spine (42) and conforming to the shape of the spine (42). As shown in Figure 7, the panel (80) includes a biocompatible flexible plastic substrate (81) having at least one pair of closely spaced microelectrodes (85) separated from each other by a nonconductive gap space (Lg). In some versions, the substrate (81) comprises a generally elongated, thinner (T) portion (82), at least one distally wider portion (83) traversing the longitudinal portion (82) at an angle substantially perpendicular to it, and a proximal base portion (84a or 84c) having a lateral dimension slightly larger than that of 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 around the distal portion of the spine (42) in a circular direction (R in Figure 5). The base portions (84a, 84c) are positioned on the proximal end portion of the spine (42) and are therefore protected within the lumen (48). One soldering patch (88) is provided on the base portion (84c) for each lead wire (30), and the distal end of the lead wire is soldered to the respective soldering patch (88). Thus, the soldering patches (88) are protected and insulated within the lumen (48).

[0019] As shown in Figure 6, the microelectrodes (85) (microelectrode strips) are mounted on the outer surface of each transverse portion (83), aligned with the transverse portion (83), or provided in another manner, so that each microelectrode (85) generally forms a ring microelectrode (R) when the transverse portion (83) is wound circumferentially around the spine (42). The longitudinal portion (82) may be the same width as the transverse portion (83), but the surface area coverage or thickness of the substrate may affect the flexibility of the spine (42). The microelectrodes (85) can be made from any suitable solid conductive material such as platinum or gold, or a combination of platinum and iridium. Some versions of the microelectrodes (85) are coated with iridium oxide or plasma-treated to improve the signal-to-noise characteristics of the microelectrodes.

[0020] In some versions, the spatial gap distance (Lg) separating each microelectrode (85) in a pair is in the range of approximately 50 to approximately 300 μm. In some versions, the spatial gap distance (Lg) separating each microelectrode (85) in a pair is in the range of approximately 100 to approximately 200 μm. In some versions, the spatial gap distance (Lg) separating each microelectrode (85) in a pair is approximately 50 μm. Furthermore, in some versions, each microelectrode (85) itself can have a width (W) in the range of approximately 50 μm to approximately 100 μm. In some versions, the panel (80) has a length of approximately 8.0 cm, the longitudinal portion (82) has a length of approximately 5.0 cm and a width of approximately 1.0 mm or less, and the base portion (84) has a length of approximately 3.0 cm and a width of approximately 1.2 mm. Each pair of microelectrodes (85) is spaced approximately 5.0 mm apart from adjacent pairs of microelectrodes (85), and each microelectrode (85) has a width of approximately 50 μm and a length of approximately 2.56 mm. Other appropriate dimensions and arrangements are described in further detail below.

[0021] As shown in Figure 7, the substrate (81) of this embodiment is formed from a first layer or outer layer (81a), a second layer or intermediate layer (81b), and a third layer 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 is understood that the letters "a", "b", and "c" indicate corresponding features within the layers (81a, 81b, 81c) of the substrate (81). Microelectrodes (85) are applied to the first surface (91a) of the outer layer (81a) or otherwise deposited to cover the through-holes (86a), which are formed in the layer (81a) to provide connection access for electrical traces (87b) extending along the first surface (91b) of the longitudinal portion (82b) of the second layer (81b) between the corresponding microelectrodes (85) and a soldering pad (88) held 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 layer (81b, 81c) to provide connection access for electrical traces (87b, 87c) to more proximal microelectrodes (85) and more proximal solder pads (not shown in Figure 7).

[0022] In this embodiment, the substrate (81) has three layers, each layer (81a, 81b, 81c) holding four traces (87). In this embodiment, it is understood that for each microelectrode (85), there is one corresponding trace (87) and one corresponding soldering pad (88). Each lead wire (30) is soldered to the corresponding soldering pad (88). In this regard, it is also understood that the traces (87) may be arranged differently in different patterns and / or on different layers (81), as needed or appropriately. Adjacent microelectrodes (85) are separated by space (Lg), and each microelectrode (85) may have a width (W) having the dimensions described earlier and later defined in Figure 13A.

[0023] As shown in Figures 5 and 6, the substrate (81) is fixed to the non-conductive coating (44) of the spine (42), with the longitudinal portion (82) extending longitudinally along the spine (42) and the transverse portion (83) being wound circumferentially around the spine (42). In this regard, the transverse dimension or width (W) of the transverse portion (83), and more importantly, of the microelectrode (85), with respect to the longitudinal axis LL, is equivalent to the circumference of the spine (42), and the opposing ends (85E) of the microelectrode (85) reach each other or at least are in close contact, substantially forming a ring microelectrode (R) held on the spine (42), and can function as a ring microelectrode (R). In this embodiment, the substrate (81) is fixed to the forward or distal side of the spine (42) which is adapted to contact the tissue.

[0024] As shown in Figure 5, each spine (42) is pre-formed with a slight inward curve, and the end effector (15) has an overall slightly concave configuration resembling an open umbrella. This pre-formed configuration allows each spine (42) to engage with the tissue surface (93) along almost its entire length when the end effector (15) is advanced distally to the tissue surface (93), as shown in Figure 8.

[0025] Figures 9 and 10 show components of another exemplary multi-lay end effector (117) that can be incorporated into a mapping catheter assembly (2) instead of an end effector (15), where each spine (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) in this embodiment includes multiple spines (142) fitted with multiple pairs of microelectrodes (185). The spine (42) in Figure 6 has a more circular cross-section, whereas the spine (142) in Figure 9 has a more rectangular cross-section, thereby providing a larger plane (100) to which flexible microelectrode members in the form of panels (180) can be selectively applied or fixed. Advantageously, the entire microelectrodes (185) (including their ends (180E)) are confined to the surface area of ​​the plane (100). Therefore, each spine (142) has a microelectrode (185) on only one side of each spine (142) (i.e., the tissue-contacting side of each spine (142)). Thus, as shown in Figure 10, generally, the entire microelectrode (185) is in contact with the tissue (193) when the plane (100) is in contact with the tissue (193). Having spines (142) with a rectangular cross-section where the X dimension along the plane (100) and across the LL axis is greater than the Y dimension perpendicular to the X dimension, as shown in Figure 9, can help minimize the torsion and stress on spines (142) in the area of ​​greatest bending or branching of the spine (D) (see Figure 10).

[0026] The support member (143) has a rectangular cross-section, which is employed by a heat-shrinkable nonconductive coating (144) to provide a larger plane (100). The substrate (181) of the panel (180) comprises several layers (181a, 181b, 181c) in this embodiment. However, the substrate (181) has no transverse portion, and the longitudinal portion has a transverse dimension (W) that is equal to or at least less than the transverse dimension of the plane (100), so that the substrate (181) remains constrained to the plane (100). The microelectrode (185) is elongated and thin, and in this embodiment has a rectangular shape. The microelectrode (185) can be made from 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.

[0027] 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. In some versions, the position sensor (36) includes one or more wire coils (e.g., three orthogonal 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 may be provided according to the teachings of any of the various patent documents cited herein. The end effector (117) may also include the position sensor (36) or a variation thereof. Other components and techniques that may be used to generate real-time position data related to the end effectors (15, 117) may include wireless triangulation, acoustic tracking, optical tracking, inertial tracking, etc. Alternatively, the position sensing capability may be omitted from the end effectors (15, 117).

[0028] In an exemplary use, the catheter (10) may be inserted into the patient's cardiovascular system (e.g., via the femoral artery), and the deflection control knob (11) and deflection section (14) are used to direct the end effector (15, 117) to a desired location (e.g., in or near the pulmonary veins). In some versions, an outer sheath (not shown) is positioned around the end effector (15, 117) to restrain the spine (42) as the end effector (15, 117) advances to the target location. In such versions, the outer sheath can be retracted after the end effector (15, 117) has reached or approached the target location. This positioning can be performed with the assistance of an image-guided surgical system that communicates with a position sensor (36) using known techniques. Once the end effector (15, 117) has reached the target location, the microelectrodes (85, 185) are brought into contact with cardiovascular tissue to obtain an electrocardiogram signal. The multi-ray configuration of the end effector (15, 117) allows for the simultaneous pickup of several electrocardiogram signals from various regions of anatomical structures within the cardiovascular lumen. These electrocardiogram signals can be used to provide EP mapping, thereby precisely determining the location of abnormal conductive tissue sites causing cardiac arrhythmias. Once these abnormal conductive tissue sites are identified, the EP mapping data can be used to guide the ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0029] C. Exemplary basket-end effector Figure 11 shows another exemplary end effector (200) that can be incorporated into a mapping catheter assembly (2) instead of the end effector (15). Alternatively, the end effector (200) may be incorporated into various other types of mapping catheter assemblies. The end effector (200) in this embodiment includes an expandable assembly (220) formed by an array of angularly spaced beams (222). Each beam (222) includes four pairs (230) of bipolar microelectrodes (232, 234). Each microelectrode (232, 234) is roughly rectangular and configured to pick up electrocardiogram signals from tissue, similar to 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 embodiment, the entirety of each microelectrode (232, 234) is limited to the surface facing outward from each beam (222). Thus, each beam (222) has microelectrodes (232, 234) only on one side of each beam (222) (i.e., the tissue contact side of each beam (222)). Unless otherwise described herein, various features of the end effector (200) may be configured and operated in the same manner as those of the end effectors (15, 117) described above.

[0030] The proximal end of the beam (222) is positioned within the outer shaft (210), which can be considered analogous to the mounting stem (46) described above. The distal end of the beam (222) is connected to the hub member (212). In some versions, the hub member (212) is fixed to a central inner shaft (216) 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 shown in Figure 11. When the expandable assembly (220) is in the non-expanded state, the beam (222) is biased inward to define an effective outer diameter less than or equal to the inner diameter of the outer shaft (210). In some versions, the beam (222) is elastically biased to provide the expandable assembly (220) in the expanded state. In some such versions, the outer sheath (214) is slidably positioned around the outer shaft (210). When the sheath (214) is in the distal position (for example, such that the distal end of the sheath (214) is distal to the hub member (212)), the sheath (214) constrains the beam (222) inward, thereby keeping the expandable assembly (220) in an unexpanded state. When the sheath (214) is in the proximal position (for example, such that the distal end of the sheath (214) is proximal to the expandable assembly (220), as shown in Figure 11), the beam (222) can elastically provide the expandable assembly (220) in an expanded state. In versions in which the beam (222) is elastically biased to provide the expandable assembly (220) in an expanded state, the inner shaft (216) can be omitted.

[0031] 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 a version where the inner shaft (216) is stationary longitudinally relative to the control handle (16), an actuator on the control handle (16) can drive the outer shaft (210) proximal to the inner shaft (216) to bias the expandable assembly (220) to a non-expanded state; or drive the outer shaft (210) distal to the inner shaft (216) to bias the expandable assembly (220) to an expanded state. In a version in which the outer shaft (210) is stationary longitudinally relative to the control handle (16), an actuator on the control handle (16) can drive the inner shaft (216) distal to the outer shaft (210) to bias the expandable assembly (220) to the unextended state; and drive the inner shaft (216) proximal to the inner shaft (210) to bias the expandable assembly (220) to the extended state. Various suitable forms of inputs that can be provided on the control handle (16) to provide such operation, as well as various suitable methods by which the expandable assembly (220) can transition between the unextended and extended states, will be apparent to those skilled in the art in consideration of the teachings herein.

[0032] In exemplary use, the catheter (10) may be inserted into the patient's cardiovascular system (e.g., via the femoral artery), and the deflection control knob (11) and deflection portion (14) are used to direct the end effector (200) to a desired location (e.g., in or near the pulmonary veins). As the end effector (200) advances to the target location, the expandable assembly (220) can be kept in a non-expanded state according to the teachings herein. After the end effector (200) has reached or approached the target location, the expandable assembly (220) can be moved to an expanded state according to the teachings herein. In versions in which the end effector (200) includes a position sensor such as a position sensor (36), the positioning of the end effector (200) may be performed with the assistance of an image-guided surgical system communicating with the position sensor. Once the end effector (200) has reached the target location, the microelectrodes (232, 234) can be brought into contact with cardiovascular tissue to obtain an electrocardiogram signal. The basket-shaped configuration of the end effector (200) allows various electrode pairs (230) to simultaneously contact different areas of tissue, thereby enabling the end effector (200) to simultaneously pick up several electrocardiogram signals from different areas of anatomical structures within the cardiovascular lumen. These electrocardiogram signals can be used to provide EP mapping, thereby precisely determining the location of abnormal conductive tissue sites causing cardiac arrhythmias. Once these abnormal conductive tissue sites are identified, the EP mapping data can be used to guide an ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0033] D. Exemplary balloon end effector Figure 12 shows another exemplary end effector (300) that can be incorporated into a mapping catheter assembly (2) instead of the end effector (15). Alternatively, the end effector (300) may be incorporated into various other types of mapping catheter assemblies. The end effector (300) in this embodiment includes an expandable assembly (320) formed by an expandable balloon (324) on which a plurality of flex circuits (322) are fixed. The flex circuits (322) are positioned in an array that is angularly spaced around the balloon (324). Each flex circuit (322) includes a flexible substrate (326) having four pairs (330) of bipolar microelectrodes (332, 334). Each microelectrode (332, 334) is roughly rectangular and configured to pick up electrocardiogram signals from tissue, similar to 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 embodiment, the entirety of each microelectrode (332, 334) is limited to the outward-facing surface of each flexible substrate (326). Thus, each flexible substrate (326) has microelectrodes (332, 334) on only one side of each flexible substrate (326) (i.e., the tissue-contact side of each flexible substrate (326)). Unless otherwise described herein, various features of the end effector (300) can be configured and operated in the same manner as the end effectors (15, 117) described above.

[0034] The proximal end of the flex circuit (322) terminates distal to the proximal end of the balloon (324). The distal end of the flex circuit (322) is joined to a hub (312) located at the distal end of the balloon (324). The balloon (324) is located at the distal end of the outer shaft (310), which can be considered analogous to the mounting stem (46) described above. The balloon (324) is in fluid communication with a source of expansion fluid (e.g., saline solution), which is driven into the balloon (324) to transition it into an inflated state, thereby providing an expandable assembly (320) in an expanded state (as shown in Figure 12). The expansion fluid can be withdrawn from the balloon (324) to transition the balloon (324) from an inflated state to a deflated state, thereby transitioning the expandable assembly (320) to a deflated state. In some versions, a central shaft (not shown) is positioned within the balloon (324) to maintain a consistent distance between the hub (312) and the distal end of the outer shaft (310), regardless of whether the expandable assembly (320) is in an expanded or de-expanded state. Various suitable methods for inflating and deflating the balloon (324) will be apparent to those skilled in the art in light of the teachings herein.

[0035] In exemplary use, the catheter (10) may be inserted into the patient's cardiovascular system (e.g., via the femoral artery), and the deflection control knob (11) and deflection portion (14) are used to direct the end effector (300) to a desired location (e.g., in or near the pulmonary veins). As the end effector (300) advances to the target location, the expandable assembly (300) may be kept in a non-expanded state according to the teachings herein. After the end effector (300) has reached or approached the target location, the expandable assembly (320) may be moved to an expanded state according to the teachings herein. In versions in which the end effector (300) includes a position sensor such as a position sensor (36), the positioning of the end effector (300) may be performed with the assistance of an image-guided surgical system communicating with the position sensor. Once the end effector (300) reaches the target site, the microelectrodes (332, 334) are brought into contact with cardiovascular tissue to obtain electrocardiogram signals. The spherical configuration of the end effector (300) allows various electrode pairs (330) to simultaneously contact different areas of tissue, thereby enabling the end effector (300) to simultaneously pick up several electrocardiogram signals from different areas of anatomical structures within the cardiovascular lumen. These electrocardiogram signals can be used to provide EP mapping, thereby precisely determining the location of abnormal conductive tissue sites causing cardiac arrhythmias. Once these abnormal conductive tissue sites are identified, the EP mapping data can be used to guide the ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0036] II. Exemplary Microelectrode Configurations for Mapping Catheter End-Effectors In some conventional EP mapping devices, such as conventional mapping catheters equipped with electrodes as known in the art, the electrocardiogram signals picked up by the electrodes may contain a significant, if not the majority, far-field signals generated from cardiovascular structures other than the specific structure targeted by the microelectrode. For example, a physician may place a microelectrode in contact with cardiac tissue (e.g., pulmonary veins) to detect electrocardiogram signals in that part of the heart. In some such cases, the atria of a patient's heart may generate electrocardiogram signals with larger amplitudes than those in that part (e.g., in the pulmonary veins), and these electrocardiogram signals may be picked up as far-field signals by the microelectrode in the pulmonary veins. Other areas of cardiac tissue may also transmit far-field signals that are picked up by the microelectrode in the pulmonary veins (or another microelectrode placed elsewhere in the cardiovascular lumen at a certain distance from the cardiac tissue generating the far-field signals). These far-field signals are added to the near-field components, ultimately resulting in an electrocardiogram signal that is artificially complex, fragmented, and therefore difficult to interpret.

[0037] Figure 14 shows a graph (500) of three electrocardiogram signal plots (502, 504, 506) from a subject with atrial fibrillation, which are segmented due to the fibrillation and far-field signaling of the signals. Those skilled in the art will understand that the plots (502, 504, 506) represent voltages over time, as would be sensed by microelectrodes in contact with tissue. (As just one example, plots (502, 504, 506) could represent electrocardiogram signals picked up by three different pairs of microelectrodes positioned within the patient's heart.) To the extent that a physician is checking electrocardiogram signals to identify a specific location within the pulmonary veins or any part of cardiac tissue that is generating an abnormal electrical signal (and thus to identify a target site for ablation or other treatment), the segmentation shown in plots (502, 504, 506) can make it substantially difficult to identify and accurately annotate the timing and cadence of polarization / depolarization cycles occurring within the tissue. In other words, it would be difficult for a physician to distinguish between relatively small, close potentials (e.g., from local tissue) and more distant potentials. These are important aspects of electrophysiological ablation procedures, as the ablation target is based on the analysis of electrical signals recorded by the catheter. The inventors have devised the microelectrodes described and illustrated herein to provide an electrocardiogram signal that substantially does not contain the signal fractions routinely found in a patient's atrial fibrillation substrate. This particular type of signal fraction should not be confused with noise originating from electrical devices outside the patient (e.g., operating room equipment, mobile phones, Wi-Fi signals, etc.). The signal fractions discussed herein are due to signals generated in the cardiac tissue inside the patient, not to noise or other electrical signals generated by artificial equipment or devices located inside or outside the patient. In fact, such fractions can be found in the electrocardiogram signal even if the patient were to be placed in an environment free from noise or other electrical signals generated by artificial equipment or devices located inside or outside the patient.

[0038] To the extent that software or other forms of signal processing may be intended to address fractions from signals generated within the cardiac tissue of a patient, such software or other forms of signal processing may be considered unreliable by physicians. Therefore, we have devised electrode-based solutions for obtaining an electrocardiogram signal that is substantially free from fractions caused by atrial fibrillation and complex wavefront interactions in the fibrillating substrate of patients with persistent AF. Multiple mechanisms have been identified or hypothesized to generate fractionated electrical signals. These include wavefront collisions, anisotropy, fibrosis, and swirling waves. Whatever the mechanism, the majority of the fractionation is due to the fact that the electrodes sense signals from tissues other than those in direct contact with them. Below are some examples of microelectrode configurations and arrangements that can provide an electrocardiogram signal that is substantially free from fractions caused by far-field signals generated within the patient's cardiovascular system, without requiring additional software or other signal processing solutions intended to reduce fractions caused by far-field signals generated within the patient's cardiovascular system.

[0039] The following description relates to various arrangements and configurations that may be used for the microelectrodes (85, 185, 232, 234, 332, 334) of any of the end effectors (15, 117, 200, 300) described herein. For the purpose of abbreviation, referring to Figure 13, the microelectrodes (85, 185, 232, 234, 332, 334) will be collectively referred to below as the pair (400) of microelectrodes (402, 404). The following teachings should be understood to be applicable to all pairs (220, 320) of the above-mentioned microelectrodes (85, 185, 232, 234, 332, 334). Those skilled in the art will recognize that the following teachings can be readily applied to various other types of electrodes in various other types of instruments, and as a result, the following teachings are not necessarily limited to the above-mentioned microelectrodes (85, 185, 232, 234, 332, 334).

[0040] Figure 13A shows microelectrodes (402, 404) having widths (W) and lengths (L), respectively, with a gap (Lg) separating them. In this embodiment, the width (W) of microelectrode (402) is equal to the width (W) of microelectrode (404); the length (L) of microelectrode (402) is equal to the length (L) of microelectrode (404). Thus, both microelectrodes (402, 404) have the same surface area (l*w) in this embodiment. The microelectrodes (402, 404) are oriented parallel to each other such that the two nearest substantially parallel surfaces (402a, 404a) define the longitudinal axis Le-Le of the microelectrode pair as illustrated in Figures 13A, 13C, and 13D. In the preferred embodiment shown in Figure 13A, the microelectrodes (402, 404) are positioned such that their length (L) extends parallel to the longitudinal axis LL of the structure on which the microelectrodes (402, 404) are mounted (e.g., a spine (42, 142), a beam (222), a flexible substrate (326), etc.); and their width (W) extends substantially parallel to the longitudinal axis Le-Le of the electrodes, or substantially perpendicular to the longitudinal axis LL of the structure on which the microelectrodes (402, 404) are mounted. The microelectrodes (402, 404) are positioned such that they are spaced apart from each other along the length of the structure on which the microelectrodes (402, 404) are mounted, and the gap (Lg) extends between the two nearest surfaces (402a, 404a) of the microelectrodes. For the sake of naming convenience in this embodiment, the gap (Lg) is set to be substantially parallel to the longitudinal axis LL of the structure in which the microelectrodes (402, 404) are mounted. In this embodiment, the microelectrodes (402, 404) are rectangular, but the microelectrodes (402, 404) may instead have any other suitable shape. Various other suitable shapes will be apparent to those skilled in the art in light of the teachings herein.

[0041] The inventors have determined that any electrode arrangement that reduces or substantially eliminates a fractional signal without signal processing applied to the sensed signal may require that the pair of electrodes conform to the following empirical rules: (1) the length (L) of the electrodes must always be at least equal to the gap (Lg) between the pair of electrodes, and (2) the ratio of the area of ​​the gap (Ag) to the area of ​​one electrode (Ae) must be 1 or less. In simpler terms, this can be rephrased as (1) L ≥ Lg, and (2) Ag / Ae ≤ 1. Various permutations of electrode and gap configurations that can achieve signal fraction reduction (without signal processing) can be seen in Table 1. In Table 1, electrode and gap configurations conforming to the first and second aspect ratios can reduce or substantially eliminate the fractional signal without using signal processing. [Table 1]

[0042] The sensing and recording of electrocardiogram signals using the electrode configuration of the present invention is advantageous in that it does not require the application of special signal processing other than conventional low-pass and high-pass filters (obvious to those skilled in the art) to present an electrocardiogram with little or substantially no fractional or far-field signals. Signal processing to reduce or eliminate far-field signals from a 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 locally generated by the cardiac tissue.

[0043] As a further example, the surface area of ​​each microelectrode (402, 404) may be less than or equal to approximately 0.4 square millimeters; any surface area between approximately 0.05 square millimeters and approximately 0.4 square millimeters; or any surface area between approximately 1 square millimeter and approximately 0.4 square millimeters. As used herein, the term “area” or “surface area” is the amount of unit square (in appropriate dimensional units, e.g., millimeters) that may be contained within or conformed to the two-dimensional planar boundary of the electrode. The term “area” or “surface area” does not imply “surface roughness”; “surface texture”; “fractal surface area”; or any measurement relating to the surface profile or fractal of such area. Similarly, if the electrode is rolled or pressed onto a non-planar substrate, the area (or surface area) of the electrode is the area spread out in a two-dimensional planar shape. And if the electrode includes a three-dimensional configuration, the relevant “area” or “surface area” of such electrode is the plane that is in direct physical contact with the heart tissue.

[0044] As just one example of linear electrodes, the length (L) of each microelectrode (402, 404) can be any length from approximately 100 μm to approximately 1 mm; any length from approximately 100 μm to approximately 300 μm; any length from approximately 300 μm to approximately 500 μm; or any length from approximately 500 μm to approximately 1 mm.

[0045] As just one example of linear electrodes, the width (W) of each microelectrode (402, 404) can be any width from approximately 800 μm to approximately 1 mm; or any width from approximately 800 μm to approximately 0.5 mm.

[0046] As just one further example, the gap distance (Lg) between each microelectrode (402, 404) can be any distance from approximately 50 μm to approximately 1 mm; or any distance from approximately 50 μm to approximately 0.5 mm.

[0047] In one version, schematically shown in Figure 13A, each electrode in the electrode pair has a generally rectangular configuration, with dimensions (width W) of approximately 800 μm when measured along the longitudinal axis Le-Le of the microelectrode (or perpendicular to the longitudinal axis LL), and a longitudinal dimension (length L) of approximately 300 μm, substantially parallel to axis LL, providing a single electrode surface area of ​​approximately 0.24 square mm and a gap length (Lg) measured between the two nearest surfaces (402a, 404a) of each microelectrode. In other words, the gap length (Lg) can be seen as approximately 200 μm, substantially perpendicular to the longitudinal axis Le-Le of the microelectrode (or substantially parallel to the longitudinal axis LL), and the gap width is the same as the electrode width W with a gap surface area of ​​approximately 160 μm.

[0048] In an alternative version, the microelectrodes (402, 404) in Figure 13A can be rotated by approximately 90 degrees so that the longitudinal axes Le-Le of the microelectrodes coincide with (or are parallel to) the longitudinal axis LL of the spine (42), as shown by the microelectrodes (402', 404') in Figure 13C. Note that the orientation of the microelectrodes is not limited to the longitudinal axis Le-Le at a specific angle with respect to the longitudinal axis LL, but can be any orientation as long as the two nearest surfaces of each microelectrode pair are substantially parallel, as shown by the electrode pair (402'', 404'') or the electrode pair (402'''', 404'''') in Figure 13D. In Figure 13D, we devised an electrode configuration such that the electrodes can be in any orientation (and number of electrodes) as long as at least two nearest surfaces of each microelectrode are substantially parallel and the gap distance Lg is between the nearly parallel surfaces. Specifically, for each group of electrodes, there may be at least two nearest surfaces that are roughly parallel to each other in order to reach a gap Lg. For example, with respect to the upper group of four electrodes (404''', 406, 402''', 408) in Figure 13D; electrode (404''') has a surface that is roughly parallel to the surface of electrode (406 or 408) and forms a first pair (404''', 406) or a second pair (404''', 408) having a gap Lg for the first and second pairs; electrode (404''') has a surface that is roughly parallel to the surface of electrode (402''') and forms a third electrode pair having a gap Lg; electrode (406) has a surface that is roughly parallel to electrode (402''') and forms a fourth electrode pair. With respect to the lower group of electrodes in Figure 13D, electrode (404''') has a surface substantially parallel to the surface of electrodes (406', 402''') and defines a gap Lg; electrode (406') has its respective surface substantially parallel to the respective surface of electrodes (404''', 402''') and defines its respective gap Lg.

[0049] In versions where the electrode pair configuration may be of a shape other than a straight line, such as circular (Figure 13B), polygonal (Figure 13D), or curved electrodes, a conversion factor CF may be used to determine the appropriate gap distance between the electrodes based on the known planar area of ​​either one of the electrodes in the pair. The conversion factor CF may range from approximately 2 to 0.1, which is the reciprocal of the same root dimensional unit as the planar area of ​​the electrodes. In one embodiment, if the planar area of ​​one electrode is approximately 0.08 square mm, the minimum gap distance (Lg) along the longitudinal axis extending through both electrodes can be obtained by applying the conversion factor CF (which is the reciprocal of the same root dimensional unit as the area or mm) such that the gap distance Lg reaches approximately 100 μm. -1 It can be determined by ) in another embodiment where the area of ​​one electrode is 0.24 square mm, the conversion factor CF (the reciprocal of the same root dimension unit or mm) -1 (The size is 1.25 mm) -1 The following is possible, giving a minimum gap distance Lg range from approximately 300 μm to approximately 24 μm. Regardless of the electrode shape, the preferred conversion factor CF (reciprocal of the same square root unit relative to the electrode area) is approximately 0.83.

[0050] 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), and as a result, the microelectrodes (402, 404) pick up only ECG signals generated by the tissue (e.g., pulmonary veins) in contact with the microelectrodes (402, 404). Figure 15 shows a graph (600) of three ECG signal plots (602, 604, 606) substantially free of fractions, which represent signals picked up by the microelectrodes (402, 404) configured and arranged according to the above teaching. Those skilled in the art will understand that the plots (602, 604, 606) show voltages over time, as would be sensed by microelectrodes in contact with tissue. As just one example, plots (602, 604, 606) can represent electrocardiogram signals picked up by three different microelectrode pairs (400) positioned within the patient's pulmonary veins. In areas where other cardiac structures (e.g., atria) are generating far-field signals with considerable amplitude, the microelectrode pairs (400), due to the configuration and arrangement of the electrodes (402, 404) of each pair (400) as described above, do not pick up these far-field signals. Instead, plots (602, 604, 606) show only potentials from the relevant region of the pulmonary veins themselves.

[0051] These plots in Figure 15 (602, 604, 606) do not contain the same type of fractionation as the plots in Figure 14 (502, 504, 506), so that physicians can more easily annotate the wavefront timing and potentially perform a better diagnosis of wavefront direction, source, and cycle length to determine the specific location in the tissue associated with the abnormal electrical signal; thereby allowing for a more reliable and accurate identification of the appropriate location for treatment (e.g., ablation). It should be understood that the improvement in the electrocardiogram signals in Figure 15 over those in Figure 14 is simply due to the configuration and arrangement of the electrodes (402, 404) of each pair (400) as described above. In this embodiment, the improvement in the electrocardiogram signals in Figure 15 over those in Figure 14 is not due to the use of signal filtering algorithms or other signal processing techniques.

[0052] III. Exemplary Combinations The following embodiments relate to various non-exclusive methods by which the teachings herein can be combined or applied. It should be understood that the following embodiments are not intended to limit the scope of any claims that may be presented at any time in this application or any subsequent application thereof. No abandonment is intended. The following embodiments are provided for illustrative purposes only. Various teachings herein are intended to be arranged and applied in many other ways. Also, some modifications may omit certain features mentioned in the following embodiments. Accordingly, none of the embodiments or features mentioned below should be considered important unless explicitly indicated at a later date by the inventor or a successor of the inventor's interests. If any claim containing additional features other than those mentioned below is filed in this application or any subsequent application relating to this application, those additional features shall not be presumed to have been added for any reason relating to patentability.

[0053] Example 1 A device comprising (a) a shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit an anatomical passage within the cardiovascular system of a subject, the end effector comprises at least one electrode pair, the at least one electrode pair configured to contact cardiovascular tissue and thereby pick up an electrocardiogram signal, each electrode pair comprising (i) a first electrode having a first surface area in square units, and (ii) a second electrode having a first surface area, wherein the first and second electrodes are spaced apart from each other by a gap distance, the gap distance being defined by multiplying the first surface area by a conversion coefficient in the range of about 0.1 to about 2, which is the reciprocal of the square root of the first surface area in the same units.

[0054] Example 2 The apparatus according to Example 1, wherein the end effector further comprises a plurality of elongated spines and a plurality of electrode pairs, the electrode pairs being fixed to the spines.

[0055] Example 3 The apparatus according to Embodiment 2, wherein the shaft defines a longitudinal axis, the spines extend outward away from the longitudinal axis, and the spines have free ends oriented away from the longitudinal axis.

[0056] Example 4 The apparatus according to Example 2, wherein the spines are configured to bend outward in an arc shape and converge distally to form a basket structure.

[0057] Example 5 The apparatus according to Example 2, wherein the end effector further includes an inflatable member, and the spine is fixed to the outer surface of the inflatable member.

[0058] Example 6 The apparatus according to one or more of Examples 1 to 5, wherein the first surface area includes approximately 0.95 square millimeters or less.

[0059] Example 7 The apparatus according to one or more of Examples 1 to 5, wherein the first surface area includes approximately 0.4 square millimeters or less.

[0060] Example 8 The apparatus described in one or more of Examples 1 to 7, wherein the gap distance includes any distance from approximately 50 μm to approximately 3 mm.

[0061] Example 9 The apparatus as described in Example 8, wherein the gap distance includes any distance from approximately 50 μm to approximately 0.5 mm.

[0062] Example 10 The apparatus according to one or more of Examples 1 to 9, wherein the end effector includes at least one electrode support member associated with at least one electrode pair, each electrode support member including a first side and a second side, and the electrode pair is located on only one of the sides of the corresponding electrode support member.

[0063] Example 11 The apparatus according to one or more of Examples 1 to 10, wherein the first and second electrodes of each electrode pair contain a biocompatible metal or a conductive polymer.

[0064] Example 12 The apparatus according to Example 11, wherein the biocompatible metal includes a metal selected from one of platinum, palladium, cobalt-chromium, nitinol, gold, or any combination thereof.

[0065] Example 13 The apparatus according to one or more of Examples 11 to 12, wherein the biocompatible metal is coated with iridium oxide.

[0066] Example 14 The apparatus described in one or more of Examples 11 to 13, wherein the biocompatible metal is plasma-treated.

[0067] Example 15 The apparatus according to one or more of Examples 1 to 14, wherein at least one electrode pair is configured to pick up the electrocardiogram signal of the nearest tissue in contact with the electrode pair without fractionation due to far-field interaction.

[0068] Example 16 The apparatus according to one or more of Examples 1 to 14, wherein at least one electrode pair is configured to collect an electrocardiogram signal from the cardiac tissue in contact with the electrode pair, and the electrocardiogram signal collected by the electrode pair is a signal in which the fraction during fibrillation of the cardiac tissue is significantly reduced.

[0069] Example 17 The apparatus according to one or more of Examples 1 to 16, wherein the electrode surface area includes any surface area from about 0.05 square millimeters to about 1 square millimeter, and a gap length (Lg) from about 100 μm to about 500 μm.

[0070] Example 18 The apparatus according to one or more of Examples 1 to 16, wherein the first surface area includes any surface area between approximately 0.24 square millimeters and approximately 0.4 square millimeters.

[0071] Example 19 The end effector is sized to fit into anatomical passages within the human cardiovascular system, as described in one or more of Examples 1 to 18.

[0072] Example 20 The apparatus according to one or more of Examples 1 to 19, wherein the first electrode and the second electrode are each rectangular, and the first surface area is defined by the first length of the first electrode and the second electrode and the first width of the first electrode and the second electrode.

[0073] Example 21 The apparatus according to Example 20, wherein the electrode pair includes configurations other than a linear planar shape.

[0074] Example 22 The apparatus according to one or more of Examples 20 to 21, wherein the first length includes any length from approximately 100 μm to approximately 750 μm.

[0075] Example 23 The apparatus according to one or more of Examples 20 to 21, wherein the first width includes any width from approximately 800 μm to approximately 1 mm.

[0076] Example 24 The apparatus as described in one or more of Examples 20 to 21, wherein the gap distance includes any distance from approximately 50 μm to approximately 3 mm.

[0077] Example 25 The first width includes any width from about 800 μm to about 0.5 mm, and the device described in any one or more of Examples 20 to 21.

[0078] Example 26 The gap distance is determined by the product of the area of one electrode up to 1 square millimeter and about 1.25 mm -1 The device described in any one or more of Examples 20 to 25, determined by the following conversion factor.

[0079] Example 27 The conversion factor is about 0.83 mm -1 The device described in Example 26.

[0080] Example 28 The conversion factor is about 0.2 mm -1 The device described in Example 26.

[0081] Example 29 The conversion factor is about 0.4 mm in the root dimension of the electrode area -1 The device described in Example 26.

[0082] Example 30 The conversion factor is about 1 mm -1 The device described in Example 26.

[0083] Example 31 The conversion factor is about 0.5 mm -1 The device described in Example 26.

[0084] Example 32 The longitudinal axis includes the longitudinal axis defined by the two closest substantially parallel surfaces of the microelectrode, and the device described in any one of Examples 1 to 31.

[0085] Example 33 An apparatus comprising (a) a shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit an anatomical passage within the human cardiovascular system, the end effector comprises at least one electrode pair, the at least one electrode pair configured to contact cardiovascular tissue and thereby pick up an electrocardiogram signal, each electrode pair comprising (i) a first electrode having a first surface area of ​​about 1 square millimeter or less, 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 the two nearest substantially parallel surfaces of the respective first and second electrodes, the gap distance (Lg) being about 1.25 mm between the first or second surface area. -1 A device containing any value derived from the product of the following conversion coefficients.

[0086] Example 34 The apparatus according to Example 33, wherein the second surface area is equal to the first surface area.

[0087] Example 35 The apparatus according to one or more of Examples 33 to 34, wherein the first surface area includes 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.

[0088] Example 36 The apparatus described in one or more of Examples 33 to 35, wherein the gap distance (Lg) includes any distance between approximately 50 μm and approximately 500 μm.

[0089] Example 37 The apparatus according to one or more of Examples 33 to 35, wherein the gap distance includes any distance between approximately 100 μm and approximately 200 μm.

[0090] Example 38 The apparatus according to one or more of Examples 33 to 37, wherein the first electrode and the second electrode include substantially identical curved planar configurations.

[0091] Example 39 The apparatus according to one or more of Examples 33 to 37, wherein the first electrode and the second electrode include substantially identical linear planar configurations.

[0092] Example 40 The apparatus according to one or more of Examples 33 to 39, wherein the first width and gap distance have a ratio of approximately 5:1.

[0093] Example 41 A device comprising (a) a shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit an anatomical passage within the cardiovascular system of a subject, the end effector comprises at least one electrode pair, the at least one electrode pair configured to contact cardiovascular tissue and thereby pick up an electrocardiogram signal, each electrode pair comprising a first electrode and a second electrode spaced apart from each other along the longitudinal axis by a gap area (Ag) located between them, the gap area (Ag) having a gap length (Lg) with respect to the longitudinal axis, and (i) the length (L) of one of the electrodes along the longitudinal axis is equal to or longer than the gap length; and (ii) the ratio of the area defined by the gap area (Ag) to the area of ​​one electrode (Ae) is 1 or less.

[0094] Example 42 The apparatus described in Example 41, combined with one or more of Examples 2 to 32.

[0095] IV. Others In some versions, the end effectors (15, 117, 200, 300) are configured to provide RF ablation in addition to providing EP mapping functionality. In some such versions, the end effectors (15, 117, 200, 300) include additional electrodes dedicated to providing RF ablation. Such RF ablation capability may be provided in accordance with the teachings of any of the various patent documents cited herein. Alternatively, the RF ablation capability may be omitted from the end effectors (15, 117, 200, 300).

[0096] It should be understood that any of the embodiments described herein may include, in addition to or instead of, a variety of other features. For example, any of the embodiments described herein may include one or more of the various features disclosed in any of the various references cited herein.

[0097] It should be understood that any one or more of the teachings, expressions, embodiments, examples, etc., described herein can be combined with any one or more of the other teachings, expressions, embodiments, examples, etc., described herein. Therefore, the teachings, expressions, embodiments, examples, etc. described herein should not be viewed in isolation. Various appropriate ways in which the teachings herein can be combined will be readily apparent to those skilled in the art, given the teachings herein. Such modifications and variations are intended to be included within the claims.

[0098] While various versions of the present invention have been shown and described herein, further modifications of the methods and systems described herein can be achieved by appropriate modifications by those skilled in the art without departing from the scope of the invention. Some of such potential modifications are mentioned, while others will be obvious to those skilled in the art. For example, the embodiments, versions, geometric shapes, materials, dimensions, ratios, steps, etc. described above are illustrative and not essential. Accordingly, it should be understood that the scope of the invention should be considered in terms of the following claims and is not limited to the details of the structure and operation shown and described herein and in the drawings.

[0099] [Implementation Method] (1) A device, (a) Shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit the anatomical passages within the cardiovascular system of the subject, the end effector includes at least one electrode pair, the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair includes a first electrode and a second electrode spaced apart from each other along the longitudinal axis by a gap area (Ag) located between them, the gap area (Ag) having a gap length (Lg) with respect to the longitudinal axis, (i) The length (L) of one of the electrodes along the longitudinal axis is equal to or longer than the gap length, (ii) A device in which the ratio of the area defined by the gap area (Ag) to the area of ​​one electrode (Ae) is 1 or less. (2) The apparatus according to Embodiment 1, wherein the end effector further comprises a plurality of elongated spines and a plurality of electrode pairs, the electrode pairs being fixed to the spines. (3) The apparatus according to Embodiment 2, wherein the spine includes each free end extending along the longitudinal axis. (4) The apparatus according to Embodiment 2, wherein the spines are configured to bend outward in an arc shape and converge distally to form a basket structure. (5) The apparatus according to Embodiment 2, wherein the end effector further includes an inflatable member, and the spine is fixed to the outer surface of the inflatable member.

[0100] (6) The apparatus according to any one of embodiments 1 to 5, wherein the first surface area includes about 0.95 square millimeters or less. (7) The apparatus according to any one of embodiments 1 to 5, wherein the first surface area includes about 0.4 square millimeters or less. (8) The apparatus according to any one of Embodiments 1 to 7, wherein the gap distance includes any distance from about 50 μm to about 3 mm. (9) The apparatus according to Embodiment 8, wherein the gap distance includes any distance from about 50 μm to about 0.5 mm. (10) The apparatus according to any one of embodiments 1 to 9, wherein the end effector includes at least one electrode support member associated with the at least one electrode pair, each electrode support member including a first side and a second side, and the electrode pair is on only one of the side faces of the corresponding electrode support member.

[0101] (11) The apparatus according to any one of embodiments 1 to 10, wherein the first electrode and the second electrode of each electrode pair include a biocompatible metal or a conductive polymer. (12) The apparatus according to Embodiment 11, wherein the biocompatible metal includes a metal selected from platinum, palladium, cobalt-chromium, nitinol, gold, or any combination thereof. (13) The apparatus according to embodiment 11 or 12, wherein the biocompatible metal is coated with iridium oxide. (14) The apparatus according to any one of embodiments 11 to 13, wherein the biocompatible metal is plasma treated. (15) The apparatus according to any one of embodiments 1 to 14, wherein the at least one electrode pair is configured to pick up the electrocardiogram signal of the nearest tissue in contact with the electrode pair without fractionation due to far-field interaction.

[0102] (16) The apparatus according to any one of embodiments 1 to 14, wherein the at least one electrode pair is configured to collect an electrocardiogram signal from the cardiac tissue in contact with the electrode pair, and the electrocardiogram signal collected by the electrode pair is a signal in which the fraction during fibrillation of the cardiac tissue is significantly reduced. (17) The apparatus according to any one of embodiments 1 to 16, wherein the electrode surface area includes any surface area from about 0.05 square millimeters to about 1 square millimeter, and a gap length (Lg) from about 100 μm to about 500 μm. (18) The apparatus according to any one of embodiments 1 to 16, wherein the first surface area includes any surface area ranging from about 0.24 square millimeters to about 0.4 square millimeters to about 1 square millimeter. (19) The apparatus according to any one of embodiments 1 to 18, wherein the end effector is sized to fit an anatomical passage within the human cardiovascular system. (20) The apparatus according to any one of embodiments 1 to 19, wherein the first electrode and the second electrode are each rectangular, and the first surface area is defined by the first length of the first electrode and the second electrode and the first width of the first electrode and the second electrode.

[0103] (21) The apparatus according to embodiment 20, wherein the electrode pair includes a configuration other than a linear planar shape. (22) The apparatus according to Embodiment 20 or 21, wherein the first length includes any length from about 100 μm to about 750 μm. (23) The apparatus according to Embodiment 20 or 21, wherein the first width includes any width from about 800 μm to about 1 mm. (24) The apparatus according to Embodiment 20 or 21, wherein the gap distance includes any distance from about 50 μm to about 3 mm. (25) The apparatus according to Embodiment 20 or 21, wherein the first width includes any width from about 800 μm to about 0.5 mm.

[0104] (26) The gap distance is the area of ​​one electrode up to 1 square millimeter and approximately 1.25 mm -1The apparatus according to any one of embodiments 20 to 25, determined by the product of the following conversion coefficients. (27) The conversion coefficient is approximately 0.83 mm -1 The apparatus according to embodiment 26. (28) The conversion coefficient is approximately 0.2 mm -1 The apparatus according to embodiment 26. (29) The conversion coefficient is approximately 0.4 mm², which is the root dimension of the area of ​​the electrode. -1 The apparatus according to embodiment 26. (30) The conversion coefficient is approximately 1 mm -1 The apparatus according to embodiment 26.

[0105] (31) The conversion coefficient is approximately 0.5 mm -1 The apparatus according to embodiment 26. (32) The apparatus according to any one of embodiments 1 to 31, wherein the longitudinal axis includes a longitudinal axis defined by two substantially parallel surfaces of the microelectrode. (33) A device, (a) Shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit an anatomical passage within the human cardiovascular system, the end effector includes at least one electrode pair, the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up an electrocardiogram signal, and each electrode pair is (i) A first electrode having a first surface area of ​​approximately 1 square millimeter or less, (ii) a second electrode having a second surface area, The first electrode and the second electrode are spaced apart from each other by a gap distance defined by the two nearest substantially parallel surfaces of the first electrode and the second electrode, The gap distance (Lg) is approximately 1.25 mm from either the first surface area or the second surface area. -1 A device containing any value derived from the product of the following conversion coefficients. (34) The apparatus according to embodiment 33, wherein the second surface area is equal to the first surface area. (35) The apparatus according to Embodiment 33 or 34, wherein the first surface area includes an area selected from about 0.08 square millimeters, 0.24 square millimeters, 0.4 square millimeters, 0.5 square millimeters, or 1 square millimeter.

[0106] (36) The apparatus according to any one of embodiments 33 to 35, wherein the gap distance (Lg) includes any distance from about 50 μm to about 500 μm. (37) The apparatus according to any one of embodiments 33 to 35, wherein the gap distance includes any distance from about 100 μm to about 200 μm. (38) The apparatus according to any one of embodiments 33 to 37, wherein the first electrode and the second electrode include substantially the same curved planar configuration. (39) The apparatus according to any one of embodiments 33 to 37, wherein the first electrode and the second electrode include substantially the same linear planar configuration. (40) The apparatus according to any one of embodiments 33 to 39, wherein the first width and the gap distance have a ratio of about 5:1.

[0107] (41) A device, (a) Shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit the anatomical passages within the cardiovascular system of the subject, the end effector includes at least one pair of electrodes, the at least one pair of electrodes is configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, and each pair of electrodes is (i) A first electrode having a first surface area in square units, (ii) a second electrode having the first surface area, wherein the first electrode and the second electrode are spaced apart from each other by a gap distance, the gap distance being defined by multiplying the first surface area by a conversion coefficient in the range of approximately 0.1 to approximately 2, which is the reciprocal of the square root of the first surface area in the same dimensional units.

Claims

1. A method for manufacturing an apparatus, (a) shaft and (b) an end effector at the distal end of the shaft, wherein the end effector is sized to fit the anatomical passages within the subject's cardiovascular system, the end effector includes at least one electrode pair, the at least one electrode pair is configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, and each electrode pair is (i) A first electrode having a first surface area in square units, (ii) a second electrode having the first surface area, The first electrode and the second electrode are arranged so as to be spaced apart from each other by a gap distance along the longitudinal axis of the end effector, A method comprising determining the gap distance based on multiplying the first surface area by a conversion coefficient in the range of 0.1 to 2, which is the reciprocal of the square root of the first surface area in the same dimensional unit.

2. The method according to claim 1, wherein the first surface area is in the range of 0.05 square millimeters to 1 square millimeter.

3. The method according to claim 2, wherein the gap distance is in the range of 100 μm to 500 μm.

4. The method according to claim 1, wherein the end effector further comprises a plurality of elongated spines, and each electrode pair is fixed to a corresponding spine among the plurality of elongated spines.

5. The method according to claim 4, wherein the shaft defines a first longitudinal axis, the spine extends outward away from the first longitudinal axis, and the spine has free ends oriented away from the first longitudinal axis.

6. The method according to claim 1, wherein the first electrode and the second electrode are oriented parallel to each other, and the two nearest substantially parallel surfaces are configured to define a second longitudinal axis substantially perpendicular to the longitudinal axis of the end effector.

7. The method according to claim 6, wherein the shaft defines a first longitudinal axis, and the first surface area is defined by a first length of the first electrode extending along the first longitudinal axis and a first width of the first electrode extending perpendicular to the first longitudinal axis.

8. The method according to claim 4, wherein the spines are configured to bend outward in an arc shape and converge distally to form a basket structure.

9. The method according to claim 7, wherein the first and second electrodes are each rectangular.

10. The method according to claim 9, wherein the first length includes any length from 100 μm to 750 μm.

11. The method according to claim 10, wherein the first width includes any width from 800 μm to 1 mm.

12. The gap distance is the first surface area up to 1 square millimeter and 1.25 mm －１ The method according to any one of claims 9 to 11, which is determined by the product of the following conversion coefficients.

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