Apparatus for diagnosis of arrhythmia

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

Disclosure Contents

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

[0002] Some catheter ablation procedures, particularly those for persistent atrial fibrillation, can be performed using electrophysiological (EP) mapping to target sites of abnormal electrical signals. Such EP mapping can involve 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 sites of abnormal conductive tissue responsible for the arrhythmia. An example of an EP mapping system is described in U.S. Patent No. 5,738,096, entitled "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, entitled "Catheter Spine Assembly with Closely-Spaced Bipolar Microelectrodes," published March 6, 2018, the disclosures of which are incorporated herein by reference in their entireties; U.S. Patent Application Publication No. 2018 / 0036078, entitled "Catheter with Soft Distal Tip for Mapping and Ablating Tubular Region," published February 8, 2018, the disclosures of which are incorporated herein by reference in their entireties; and U.S. Patent Application Publication No. 2018 / 0056038, entitled "Catheter with Bipolar Electrode Spacer and Related Methods," published March 1, 2018, the disclosures of which are incorporated herein by reference in their entireties.

[0003] In addition to the use of EP mapping, some catheter ablation procedures can be performed using an image-guided surgery (IGS) system. An IGS system can allow a physician to visually track the location of a catheter within a patient in real time in conjunction with an image of the patient's internal anatomy. Some systems, including the CARTO 3® system by Biosense Webster, Inc. of Irvine, California, can provide 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, entitled "Signal Transmission Using Catheter Braid Wires," issued 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 made or used the invention as set forth in the appended claims.

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

[0006] [Figure 1] 1 shows a top view of an exemplary mapping catheter assembly. [Figure 2] 2 shows a cross-sectional end view of the mapping catheter assembly of FIG. 1 taken along line 2-2 of FIG. 1. [Figure 3] 3 shows a cross-sectional end view of the mapping catheter assembly of FIG. 1 taken along line 3-3 of FIG. 1. [Figure 4] 2 shows a perspective, partially cross-sectional view of a distal portion of the mapping catheter assembly of FIG. 1. [Figure 5]2 shows a perspective view of the end effector of the mapping catheter assembly of FIG. 1 with a portion of the catheter sheath broken away to reveal the internal structure. [Figure 6] 6 shows an enlarged perspective view of the electrode assembly of the end effector of FIG. 5. [Figure 7] 6 shows an exploded view of the electrode assembly of the end effector of FIG. 5. [Figure 8] FIG. 6 shows a schematic side view of the end effector of FIG. 5 contacting a tissue surface. [Figure 9] 6 shows a partial perspective view of another exemplary electrode assembly that may be incorporated into the end effector of FIG. 5. [Figure 10] 10 shows a schematic side view of the end effector of FIG. 5 incorporating the electrode assembly of FIG. 9 in contact with a tissue surface. [Figure 11] 1. FIG. 4 shows a side view of another exemplary end effector that may be incorporated into the mapping catheter assembly of FIG. [Figure 12] 1. FIG. 4 shows a side view of another exemplary end effector that may be incorporated into the mapping catheter assembly of FIG. [Figure 13A] 2 shows a schematic diagram of a pair of linear electrodes that may be incorporated into the end effector of the mapping catheter assembly of FIG. 1. [Figure 13B] 2 shows a schematic plan view of a pair of curved electrodes that may be incorporated into the end effector of the mapping catheter assembly of FIG. 1. [Figure 13C] 1. FIG. 4 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 of FIG. [Figure 13D] 1. FIG. 4 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 of FIG. [Figure 14] 1 shows a plot of an electrocardiogram signal showing fractions. [Figure 15] 1 shows a plot of an electrocardiogram signal without fractionation.

[0007] Detailed Description The following description of specific examples of the present invention should not be used to limit the scope of the invention. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the present invention by way of example, not by way of 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 is, by way of illustration, one of the best modes contemplated for carrying out the invention. As will be recognized, the present invention is capable of other different or equivalent aspects without departing from the invention. Accordingly, the drawings and description should be regarded as illustrative in nature and not restrictive.

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

[0009] As used herein, the term "about" or "approximately" in connection with any numerical value or range indicates an appropriate dimensional tolerance that enables a portion or collection of components to function for its intended purpose, as described herein. More specifically, "about" or "approximately" can refer to a range of values ​​of ±10% of the recited value; for example, "about 90%" can refer to a range of values ​​of 81% to 99%. Furthermore, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject and are not intended to limit the system or method to use in humans, although use of the present invention in human patients represents a preferred embodiment.

[0010] I. Exemplary Mapping Catheter Assembly A. Overview FIG. 1 illustrates an exemplary mapping catheter assembly (2) that can be used to provide EP mapping within the heart or other cardiovascular anatomical structure within a patient. The catheter assembly (2) in this 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), the distal deflection portion being deflectable laterally relative to the proximal portion (12) in response to actuation of a deflection control knob (11) on the control handle (16), as described in further detail below. An end effector (15) is positioned at the distal end of the catheter (10). As also described in further detail below, the end effector (15) includes a plurality of spines (42) having respective free ends, each spine carrying at least one 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 incompressible along its length. As shown in FIG. 2, the proximal portion 12 of the catheter 10 includes an outer wall 17 positioned coaxially around a stiffening tube 20. By way of example only, the outer diameter of the proximal portion 12 may be less than about 8 French. The stiffening tube 20 and the outer wall 17 are both configured to provide substantial torsional stability while also providing a minimal wall thickness. Due to the torsional stability provided by the stiffening tube 20 and the outer wall 17, rotation of the control handle 16 results in corresponding rotation of the deflection portion 14 and end effector 15 of the catheter 10. In some variations, the stiffening tube 20 is omitted. A lumen 18 extends through the interior of the stiffening tube 20. Lumen (18) is sized to accommodate various components including, for example, one or more puller wires, electrode leads, irrigation tubing, and any other wires and / or cables as described below.

[0012] As shown in FIG. 3, the deflection section 14 of the catheter 10 includes a tubular body 19 defining a central lumen 23 and multiple off-axis lumens 21, 22, 24, and 25 sized to accommodate various components, as described below. In this embodiment, the tubular body 19 is formed of a more flexible material than the proximal section 12 of the catheter 10. In this embodiment, a set of lead wires 30 are housed within a non-conductive sheath 60 and extend the length of the catheter 10. As shown in FIGS. 2 and 3, the lead wires 30 and sheath 60 are positioned within the lumens 18 and 21. The lead wires 30 are coupled to microelectrodes 85, as described in more detail below. A set of puller wires 32A and 32B are housed within their respective sheaths 39 and extend the length of the catheter 10. Puller wires (32A, 32B) are positioned within lumen (18) and respective lumens (22, 24); in this example, they are angularly offset from one another by 180 degrees. The puller wires (32A, 32B) are operable to provide bidirectional lateral deflection of the deflection section (14), as described in further detail below. A guidewire tube (38) also extends the length of the catheter (10) and is positioned within the lumens (18, 23). The guidewire tube (38) is configured to slidably accommodate a conventional guidewire (not shown), which may 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 light of the teachings herein. A sensor cable (34) also extends the length of the catheter (10) and is positioned within the lumens (18, 25). The sensor cable (34) is coupled to an electromagnetic position sensor (36), as described in further detail below.

[0013] As shown in FIG. 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 length of tube attached to the distal end of the tubular body 19. The stem 46 has a central lumen 48 for accommodating various components, including the position sensor 36 and distal anchors for the pull wires 32A and 32B. In this example, the distal anchor includes a pair of washers 50D and 50P, each having a plurality of through-holes 52 and 54 that allow passage of components between the deflection portion 14 and the stem 46. The through-holes 52 and 54 are axially aligned with the lumens 22 and 24 of the tubular body 19, respectively, to receive the distal ends of the pull wires 32A and 32B. When tension is applied to the washers 50D, 50P by the pull wires 32A, 32B, the washers 50D, 50P securely abut the distal end of the tubular body 19 of the deflection section 14. Each washer 50D, 50P includes a through-hole 51 axially aligned with the lumen 21 to allow the lead wire 30 to pass from the deflection section 14 into the lumen 48. Each washer 50D, 50P also includes a through-hole 55 axially aligned with the lumen 25 to allow the sensor cable 34 to pass into the lumen 48, in which the position sensor 36 is housed. Each washer (50D, 50P) further includes an axial through-hole (53) that is axially aligned with lumen (23) and allows guidewire tube (38) to pass into lumen (48).

[0014] As shown in Figures 3-4, pull wires (32A, 32B) are provided for bidirectional deflection of deflection portion (14). Pull wires (32A, 32B) are actuated by a mechanism within control handle (16) that is responsive to thumb control knob or 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 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.

[0015] B. Exemplary Multi-Ray End Effector As shown in FIGS. 1 and 4-9, the end effector 15 of the mapping catheter assembly 2 includes a set of ring electrodes 27 positioned at the distal end of the catheter 10 and a plurality of spines 42, each having at least one pair of closely spaced bipolar microelectrodes 85. In this embodiment, the pair of microelectrodes 85 has a separation spatial gap distance of about 200 μm or less between them. In this embodiment, at least one pair of closely spaced bipolar microelectrodes 85 is 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 varied as needed. By way of example only, the end effector 15 can include two to eight spines 42; or, alternatively, more spines 42 can be included as needed. Although the spines (42) are shown with respective 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 4-6, each spine (42) has a support member (43) and a non-conductive coating (44) extending along it. The proximal portion of each spine (42) extends proximally into the lumen (48) of the stem (46). The spines (42) are uniformly spaced equiangularly from one another around the distal opening of the stem (46). An adhesive (not shown) seals the distal end of the stem (46) around the proximal portion of the spine (42), while leaving the distal end of the guidewire tube (38) open. In this embodiment, each spine support member (43) is made of a material with shape memory (e.g., nitinol). The non-conductive coating (44) may be made of any suitable material, such as a biocompatible plastic (e.g., polyurethane or PEBAX).

[0017] The leads 30 for the microelectrodes 85 carried on the spines 42 extend through both sections 12, 14 of the catheter 10 and are protected by a non-conductive sheath 60. Toward the end effector 15, the leads 30 extend through poly tubing 68, as shown in FIG. 4. The leads 30 branch at the distal end of the poly tubing 68 and extend toward each of the spines 42. While only one spine 42 is shown in FIG. 4, the poly tubing 68 can be appropriately sized to receive the proximal ends of all of the 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) secured to the outer surface of the spine (42) that conforms to the shape of the spine (42). As shown in Figure 7, the panel (80) includes a biocompatible, flexible plastic substrate (81) bearing at least one pair of closely spaced microelectrodes (85) separated by a non-conductive gap space (Lg). In some versions, the substrate (81) includes a generally elongated, thinner (T) portion (82), at least one distal wider portion (83) that intersects the longitudinal portion (82) at a substantially perpendicular angle, and a proximal base portion (84a or 84c) having a lateral dimension slightly greater 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 circumferentially around the distal portion of the spine (42) (see R in FIG. 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). A soldering patch (88) is provided on the base portion (84c), one for each lead wire (30), and the distal ends of the lead wires are soldered to the respective soldering patch (88). Thus, the soldering patch (88) is protected and insulated within the lumen (48).

[0019] As shown in FIG. 6 , a microelectrode (85) (microelectrode strip) is attached or otherwise provided on the outer surface of each transverse portion (83) in alignment with the transverse portion (83), such that each microelectrode (85) generally forms a ring microelectrode (R) when the transverse portion (83) is wrapped circumferentially around the spine (42). The longitudinal portions (82) may be the same width as the transverse portions (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 microelectrode (85) are coated with iridium oxide or plasma treated to improve the signal-to-noise characteristics of the microelectrode.

[0020] In some versions, the spatial gap distance (Lg) separating each microelectrode (85) of a pair ranges from about 50 to about 300 μm. In some versions, the spatial gap distance (Lg) separating each microelectrode (85) of a pair ranges from about 100 to about 200 μm. In some versions, the spatial gap distance (Lg) separating each microelectrode (85) of a pair is about 50 μm. Furthermore, in some versions, each microelectrode (85) itself can have a width (W) ranging from about 50 μm to about 100 μm. In some versions, the panel (80) has a length of about 8.0 cm, the longitudinal portion (82) has a length of about 5.0 cm and a width of about 1.0 mm or less, and the base portion (84) has a length of about 3.0 cm and a width of about 1.2 mm. Each pair of microelectrodes (85) is separated from an adjacent pair of microelectrodes (85) by a distance of about 5.0 mm, and each microelectrode (85) has a width of about 50 μm and a length of about 2.56 mm. Other suitable dimensions and configurations are described in more detail below.

[0021] As shown in Figure 7, the substrate (81) of this example is formed from 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 a longitudinal axis LL. It is understood that the letters "a," "b," and "c" refer to corresponding features within the layers (81a, 81b, 81c) of the substrate (81). Microelectrodes (85) are applied or otherwise deposited on the first surface (91a) of the outer layer (81a) 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 corresponding microelectrodes (85) and soldering 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 layers (81b, 81c) to provide connection access for electrical traces (87b, 87c) to the more proximal microelectrode (85) and the more proximal soldering pads (not shown in Figure 7).

[0022] In this example, the substrate (81) has three layers, with each layer (81a, 81b, 81c) carrying four traces (87). It is understood that, in this example, there is one corresponding trace (87) and one corresponding soldering pad (88) for each microelectrode (85). Each lead wire (30) is soldered to a corresponding soldering pad (88). In that regard, it is also understood that the traces (87) may be arranged 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) may have a width (W) having the dimensions described above and defined below in FIG. 13A.

[0023] As shown in Figures 5 and 6, the substrate (81) is secured 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) wrapped circumferentially around the spine (42). In that regard, the transverse dimension or width (W) of the transverse portion (83), and more importantly, of the microelectrode (85), relative to the longitudinal axis LL, is equal to the circumference of the spine (42), and the opposing ends (85E) of the microelectrode (85) reach each other or at least closely contact each other to generally form and function as a ring microelectrode (R) held on the spine (42). In this example, the substrate (81) is secured to the forward or distal side of the spine (42) adapted to contact tissue.

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

[0025] 9-10 illustrate components of another exemplary multi-lay end effector (117) that can be incorporated into the mapping catheter assembly (2) in place of the end effector (15), with each spine (142) defining 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 multiple spines (142) onto which multiple pairs of microelectrodes (185) are attached. While the spines (42) of FIG. 6 have a more circular cross-section, the spines (142) of FIG. 9 have a more rectangular cross-section, thereby providing a larger planar surface (100) onto which flexible microelectrode members in the form of panels (180) can be selectively applied or secured. Advantageously, the entirety of the microelectrodes (185), including their ends (180E), are limited to the surface area of ​​the planar surface (100). Thus, the spines (142) have microelectrodes (185) on only one side of each spine (142) (i.e., the tissue-contacting side of each spine (142)). Thus, as shown in FIG. 10, generally, the entirety of the microelectrodes (185) is in contact with the tissue (193) when the plane (100) is in contact with the tissue (193). Having a spine (142) with a rectangular cross-section, such that the X dimension along the plane (100) and transverse to the LL axis is greater than the Y dimension perpendicular to the X dimension, as shown in FIG. 9, can help minimize kinking and stress on the spine (142) in the area of ​​greatest bending or branching (D) of the spine (see FIG. 10).

[0026] The support member (143) has a rectangular cross-section that is adopted by the heat-shrinkable non-conductive coating (144) to provide a larger flat surface (100). The substrate (181) of the panel (180) includes, in this example, multiple layers (181a, 181b, 181c). However, the substrate (181) lacks lateral sections; its longitudinal sections have lateral dimensions (W) equal to or at least less than the lateral dimensions of the flat surface (100), so that the substrate (181) remains constrained on the flat surface (100). The microelectrodes (185) are elongated and thin, and in this example have a rectangular shape. The microelectrodes (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 microelectrodes (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 indicative of the position and orientation of the end effector (15) within the patient. In some versions, the position sensor (36) includes a wire coil or multiple wire coils (e.g., three quadrature coils) configured to generate an electrical signal in response to the presence of an alternating current electromagnetic field generated by a field generator positioned near the patient. Such position sensing capability may be provided in accordance with the teachings of any of the various patent documents cited herein. The end effector (117) may also include the position sensor (36) or variations thereof. Other components and techniques that may be used to generate real-time position data associated with the end effector (15, 117) may include radio triangulation, acoustic tracking, optical tracking, inertial tracking, etc. Alternatively, position sensing capability may be omitted from the end effector (15, 117).

[0028] In an exemplary use, the catheter (10) can be inserted into a patient's cardiovascular system (e.g., via the femoral artery, etc.), and the deflection control knob (11) and deflection portion (14) are used to direct the end effector (15, 117) to a desired location (e.g., in or near a pulmonary vein, etc.). In some versions, an outer sheath (not shown) can be positioned around the end effector (15, 117) to constrain the spine (42) as the end effector (15, 117) advances toward the target location. In such versions, the outer sheath can be retracted after the end effector (15, 117) reaches or approaches the target location. This positioning can be performed with assistance from an image-guided surgical system that communicates with the position sensor (36) using known techniques. Once the end effector (15, 117) reaches 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 several electrocardiogram signals to be picked up simultaneously from various regions of the anatomy within the cardiovascular cavity. These electrocardiogram signals can be used to provide EP mapping, thereby pinpointing the location of abnormal conductive tissue sites responsible for cardiac arrhythmias. Once these abnormal conductive tissue sites are identified, the EP map data can be used to guide an ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0029] C. Exemplary Basket End Effector FIG. 11 illustrates another exemplary end effector (200) that can be incorporated into the mapping catheter assembly (2) in place 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) of this example 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 of the microelectrodes (232, 234) is generally rectangular and configured to pick up electrocardiogram signals from tissue, similar to the microelectrodes (85, 185) described above. The microelectrodes (232, 234) may 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. The entirety of each microelectrode (232, 234) is confined to the outwardly facing surface of each beam (222) in this example. 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)). Except as otherwise described herein, various features of the end effector (200) may be configured and operable similarly to 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 similar to the mounting stem (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 secured to a central inner shaft (216) that is coaxially positioned in the center of the expandable assembly (220). The beam (222) is configured to transition the expandable assembly (220) between an unexpanded state and an expanded state. The expanded state is shown in FIG. 11. When the expandable assembly (220) is in the unexpanded state, the beam (222) is biased inward to define an effective outer diameter that is equal to or less than the inner diameter of the outer shaft (210). In some versions, the beam (222) is resiliently biased to provide the expandable assembly (220) in the expanded state. In some such versions, an outer sheath (214) is slidably disposed about 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) inwardly constrains the beam (222), thereby maintaining the expandable assembly (220) in an unexpanded state. When the sheath (214) is in a proximal position (e.g., such that the distal end of the sheath (214) is proximal to the expandable assembly (220), as shown in FIG. 11), the beam (222) can resiliently provide the expandable assembly (220) in an expanded state. In versions in which the beam (222) is resiliently biased to provide the expandable assembly (220) in an expanded state, the inner shaft (216) can be omitted.

[0031] As another merely exemplary 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 in which 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 urge the expandable assembly (220) to an unexpanded state; and drive the outer shaft (210) distally relative to the inner shaft (216) to urge the expandable assembly (220) to an expanded state. In versions in which 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 bias the expandable assembly 220 to an unexpanded state; and can drive the inner shaft 216 proximally relative to the inner shaft 210 to bias the expandable assembly 220 to an expanded state. Various suitable forms of input that can be provided on the control handle 16 to provide such actuation, as well as various suitable ways in which the expandable assembly 220 can transition between an unexpanded state and an expanded state, will be apparent to those skilled in the art in view of the teachings herein.

[0032] In an exemplary use, the catheter (10) can be inserted into a patient's cardiovascular system (e.g., via the femoral artery, etc.), and the deflection control knob (11) and deflection portion (14) can be used to direct the end effector (200) to a desired location (e.g., in or near a pulmonary vein, etc.). As the end effector (200) advances to the target location, the expandable assembly (220) can be maintained in an unexpanded state in accordance with the teachings herein. After the end effector (200) reaches or approaches the target location, the expandable assembly (220) can be transitioned to an expanded state in accordance with the teachings herein. In versions in which the end effector (200) includes a position sensor, such as position sensor (36), positioning of the end effector (200) can be performed with assistance from an image-guided surgical system in communication with the position sensor. Once the end effector (200) reaches the target location, the microelectrodes (232, 234) can be brought into contact with cardiovascular tissue, allowing electrocardiogram signals to be acquired. The basket-shaped configuration of the end effector (200) allows different electrode pairs (230) to contact different regions of tissue simultaneously, thereby enabling the end effector (200) to simultaneously pick up several electrocardiogram signals from different regions of the anatomy within the cardiovascular cavity. These electrocardiogram signals can be used to provide EP mapping, thereby precisely locating abnormal conductive tissue sites responsible for cardiac arrhythmias. Once these abnormal conductive tissue sites are identified, the EP map data can be used to guide an ablation catheter to ablate the tissue, thereby treating the arrhythmia.

[0033] D. Exemplary Balloon End Effector FIG. 12 illustrates another exemplary end effector (300) that can be incorporated into the mapping catheter assembly (2) in place 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) of this example includes an expandable assembly (320) formed by an expandable balloon (324) to which a plurality of flex circuits (322) are secured. The flex circuits (322) are positioned in an angularly spaced array around the balloon (324). Each flex circuit (322) includes a flexible substrate (326) having four pairs (330) of bipolar microelectrodes (332, 334). Each of the microelectrodes (332, 334) is generally rectangular and configured to pick up electrocardiogram signals from tissue, similar to the microelectrodes (85, 185) described above. The microelectrodes (332, 334) may 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. The entirety of each microelectrode (332, 334) is confined to the outwardly facing surface of each flexible substrate (326), in this example. 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)). Except as otherwise described herein, various features of the end effector (300) may be configured and operable similarly to the end effectors (15, 117) described above.

[0034] The proximal end of the flex circuit 322 terminates distally to the proximal end of the balloon 324. The distal end of the flex circuit 322 is joined to a hub 312 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 thought of as similar to the mounting stem 46 described above. The balloon 324 is in fluid communication with a source of inflation fluid (e.g., saline solution), which can be driven into the balloon 324 to transition the balloon 324 to an inflated state, thereby providing the expandable assembly 320 in an expanded state (as shown in FIG. 12 ). The inflation fluid can be withdrawn from the balloon 324 to transition the balloon 324 from an inflated state to an uninflated state, thereby transitioning the expandable assembly 320 to an unexpanded state. In some versions, a central shaft (not shown) is positioned within the balloon (324) to maintain a consistent spacing 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 unexpanded state. Various suitable methods by which the balloon (324) may be inflated and deflated will be apparent to those skilled in the art in light of the teachings herein.

[0035] In an exemplary use, catheter 10 may be inserted into a patient's cardiovascular system (e.g., via the femoral artery, etc.), and deflection control knob 11 and deflection portion 14 may be used to direct end effector 300 to a desired location (e.g., in or near a pulmonary vein, etc.). As end effector 300 advances to the target location, expandable assembly 320 may be maintained in an unexpanded state in accordance with the teachings herein. After end effector 300 reaches or approaches the target location, expandable assembly 320 may be transitioned to an expanded state in accordance with the teachings herein. In versions in which end effector 300 includes a position sensor, such as position sensor 36, positioning of end effector 300 may be performed with assistance from an image-guided surgical system in communication with the position sensor. Once the end effector 300 reaches the target location, the microelectrodes 332, 334 are brought into contact with cardiovascular tissue to obtain electrocardiogram signals. The spherical configuration of the end effector 300 allows different electrode pairs 330 to simultaneously contact different regions of tissue, thereby enabling the end effector 300 to simultaneously pick up several electrocardiogram signals from different regions of the anatomy within the cardiovascular cavity. These electrocardiogram signals can be used to provide EP mapping, thereby pinpointing the location of abnormal conductive tissue sites responsible for cardiac arrhythmias. Once these abnormal conductive tissue sites are identified, the EP map data can be used to guide an 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 instruments, such as conventional mapping catheters equipped with electrodes as known in the art, the electrocardiogram signal picked up by the electrode may contain a large, if not a large, proportion of 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., a pulmonary vein) to detect electrocardiogram signals at that site within the heart. In some such cases, the atria of the patient's heart may be generating electrocardiogram signals with amplitudes greater than those at that site (e.g., at the pulmonary vein), and those electrocardiogram signals may be picked up by the microelectrode in the pulmonary vein as far-field signals. Other regions of cardiac tissue may also transmit far-field signals that are picked up by the microelectrode in the pulmonary vein (or a microelectrode placed elsewhere within the cardiovascular cavity at some distance from the cardiac tissue generating the far-field signal). These far-field signals add to the near-field components, ultimately resulting in an electrocardiogram signal that is artificially complex and fragmented, and therefore difficult to interpret.

[0037] FIG. 14 shows a graph 500 of three electrocardiogram signal plots 502, 504, and 506 from a subject with atrial fibrillation, which are fractionated due to the fibrillatory nature of the signal as well as far-field signals. Those skilled in the art will appreciate that the plots 502, 504, and 506 represent voltage over time as sensed by microelectrodes in contact with tissue. By way of example only, the plots 502, 504, and 506 may represent electrocardiogram signals picked up by three different microelectrode pairs positioned within a patient's heart. To the extent that a physician is examining the electrocardiogram signal to identify specific locations within a pulmonary vein or any portion of cardiac tissue that are generating abnormal electrical signals (and thus identify target locations for ablation or other therapy), the fractionation shown in the plots 502, 504, and 506 can make it substantially difficult to identify and accurately annotate the timing and cadence of the polarization / depolarization cycles occurring within the tissue. In other words, it would be difficult for a physician to distinguish between relatively small, nearby potentials (e.g., from local tissue) and more distant potentials. These are important aspects of electrophysiological ablation procedures, since ablation targets are based on analysis of electrical signals recorded by a catheter. The inventors have devised the microelectrodes described and illustrated herein to provide electrocardiogram signals that are substantially free of signal fractions routinely found in a patient's atrial fibrillation substrate. This particular type of signal fraction should not be confused with noise generated by electrical devices external to the patient (e.g., operating room equipment, cell phone, Wi-Fi signals, etc.). The signal fraction addressed herein is attributable to signals generated in the patient's internal cardiac tissue, rather than noise or other electrical signals generated by artificial equipment or devices located inside or outside the patient. In fact, such fractions may be found in electrocardiogram signals even if the patient were to be placed in an environment free of 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 fractionation from signals generated within a patient's cardiac tissue, such software or other forms of signal processing may be considered unreliable by physicians. Therefore, the inventors have devised an electrode-based solution for obtaining electrocardiogram signals substantially free of fractionation caused by atrial fibrillation and complex wavefront interactions in the fibrillation substrate of patients with persistent AF. Multiple mechanisms have been identified or suspected to generate fractionated electrical signals, including wavefront collision, anisotropy, fibrosis, swirling waves, and others. Regardless of the mechanism, a large portion of the fractionation is due to the fact that the electrode senses signals other than those in direct contact with the tissue. Below are described several examples of microelectrode configurations and placements that can provide electrocardiogram signals substantially free of fractionation caused by far-field signals generated within a patient's cardiovascular system, without the need for additional software or other signal processing solutions intended to reduce the fractionation 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 with the microelectrodes (85, 185, 232, 234, 332, 334) of any of the end effectors (15, 117, 200, 300) described herein. For purposes of shorthand, and with reference to FIG. 13 , the microelectrodes (85, 185, 232, 234, 332, 334) are hereinafter collectively referred to as the microelectrodes (402, 404) of pair (400). The following teachings should be understood to be applicable to all pairs (220, 320) of microelectrodes (85, 185, 232, 234, 332, 334) described above. Those skilled in the art will also recognize that the following teachings can be readily applied to a variety of other types of electrodes in a variety of other types of instruments, and thus the following teachings are not necessarily limited to the microelectrodes (85, 185, 232, 234, 332, 334) described above.

[0040] FIG. 13A shows the microelectrodes (402, 404) as each having a width (W) and a length (L), with a gap (Lg) separating the microelectrodes (402, 404). In this example, the width (W) of the microelectrode (402) is equal to the width (W) of the microelectrode (404); the length (L) of the microelectrode (402) is equal to the length (L) of the microelectrode (404). Thus, both microelectrodes (402, 404) have the same surface area (l*w) in this example. The microelectrodes (402, 404) are oriented parallel to one another such that the two nearest substantially parallel surfaces (402a, 404a) define a longitudinal axis Le-Le of the microelectrode pair as illustratively shown in FIGS. 13A, 13C, and 13D. In a preferred embodiment shown in Figure 13A, the microelectrodes (402, 404) are positioned such that their length (L) extends parallel to the longitudinal axis L of the structure (e.g., spine (42, 142), beam (222), flexible substrate (326), etc.) to which they are attached; and their width (W) extends approximately parallel to the longitudinal axis L-L of the electrodes or approximately perpendicular to the longitudinal axis L of the structure to which they are attached. The microelectrodes (402, 404) are positioned such that they are spaced apart from one another along the length of the structure to which they are attached, with a gap (L) extending between the two nearest surfaces (402a, 404a) of the microelectrodes. For convenience of nomenclature regarding this embodiment, the gap (Lg) is intended to be substantially parallel to the longitudinal axis LL of the structure to which the microelectrodes (402, 404) are attached. In this example, 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 the fractional signal without signal processing applied to the sensed signal may require a pair of electrodes to conform to the following rules of thumb: (1) the length (L) of the electrodes must always be at least equal to the spacing gap (Lg) between the pair of electrodes, and (2) the ratio of the area of ​​the spacing gap (Ag) to the area of ​​one electrode (Ae) must be less than or equal to 1. For brevity, this can be rephrased as: (1) L≧Lg, (2) Ag / Ae≦1. Various permutations of electrode and gap configurations that can achieve signal fractional reduction (without signal processing) can be seen in Table 1. In Table 1, electrodes and gaps conforming to the first and second aspect ratios can reduce or substantially eliminate the fractional signal without the use of signal processing. [Table 1]

[0042] Sensing and recording electrocardiogram signals with the electrode configuration of the present invention is advantageous in that no special signal processing needs to be applied other than conventional low-pass and high-pass filters (as would be apparent to one skilled in the art) to present an electrocardiogram that is little or substantially free of fractional or far-field signals. It is believed that signal processing to reduce or eliminate 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.

[0043] By way of further example only, the surface area of ​​each microelectrode (402, 404) can be about 0.4 square millimeters or less; any surface area between about 0.05 square millimeters and about 0.4 square millimeters; any surface area between about 1 square millimeter and about 0.4 square millimeters. As used herein, the term "area" or "surface area" refers to a unit square quantity (in appropriate dimensional units, e.g., millimeters) that can be contained within or fitted within the two-dimensional planar boundary of the electrode. The term "area" or "surface area" does not include any meaning related to "surface roughness," "surface texture," "fractal surface area," or any measurement related to the surface profile or fractal of such an area. Similarly, if an electrode is rolled or crimped onto a non-planar substrate, the area (or surface area) of the electrode is the area spread out over the two-dimensional planar shape. And, if the electrode includes a three-dimensional configuration, the relevant "area" or "surface area" of such an electrode is the plane in direct physical contact with cardiac tissue.

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

[0045] As just one example of a linear electrode, the width (W) of each microelectrode (402, 404) can be any width between about 800 μm and about 1 mm; any width between about 800 μm and about 0.5 mm.

[0046] By way of further example only, the gap distance (Lg) of each microelectrode (402, 404) can be any distance between about 50 μm and about 1 mm; any distance between about 50 μm and about 0.5 mm.

[0047] In one version, as shown schematically in Figure 13A, each electrode of the electrode pair has a generally rectangular configuration, with a dimension (width W) of about 800 μm as measured along the microelectrode's longitudinal axis Le-Le (or measured perpendicular to the longitudinal axis LL), and a longitudinal dimension (length L) approximately parallel to axis LL of about 300 μm, providing a single electrode surface area of ​​about 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 viewed as approximately perpendicular to the microelectrode's longitudinal axis Le-Le (or approximately parallel to the longitudinal axis LL) of about 200 μm, with a gap width the same as the electrode width W, at a gap surface area of ​​about 160 μm.

[0048] In an alternative version, the microelectrodes (402, 404) in FIG. 13A can be rotated approximately 90 degrees so that the longitudinal axes Le-Le of the microelectrodes are aligned (or parallel) with the longitudinal axis L of the spine (42), as shown by the microelectrodes (402', 404') in FIG. 13C. Note that the orientation of the microelectrodes is not limited to the longitudinal axes Le-Le at a particular angle relative to the longitudinal axis L, but can be in any orientation as long as the two nearest surfaces of each microelectrode pair are substantially parallel, as shown by electrode pair (402'', 404'') or electrode pair (402''', 404''') in FIG. 13D. In FIG. 13D, we have devised an electrode configuration where the electrodes satisfy the rule of thumb that the electrodes can be of any orientation (and number of electrodes) as long as at least the two nearest surfaces of each microelectrode are substantially parallel and have a gap distance L between the approximately parallel surfaces. Specifically, for each group of electrodes, there may be at least two nearest surfaces that are generally parallel to reach the gap L. For example, for the top group of four electrodes (404''', 406, 402''', 408) in FIG. 13D , electrode (404''') has a surface that is generally parallel to the surface of electrode (406 or 408) to form a first pair (404''', 406) or a second pair (404''', 408) with a gap L for the first and second pairs; electrode (404''') has a surface that is generally parallel to the surface of electrode (402''') to form a third electrode pair with a gap L; and electrode (406) has a surface that is generally parallel to electrode (402''') to form a fourth electrode pair. With respect to the lower group of electrodes in FIG. 13D, electrode (404''') has a surface that is approximately parallel to the surfaces of electrodes (406', 402''') and defines a gap Lg; electrode (406') has a respective surface that is approximately parallel to the respective surfaces of electrodes (404''', 402''') and defines a respective gap Lg.

[0049] In versions where the electrode pair configuration may be shaped other than linear, such as circular ( FIG. 13B ), polygonal ( FIG. 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 ​​one of the electrodes in the pair. The conversion factor CF may be in the reciprocal of the same root dimensional unit as the planar area of ​​the electrodes, and may range from about 2 to 0.1. In one example, if the planar area of ​​one electrode is about 0.08 square mm, the minimum gap distance (Lg) along the longitudinal axis extending through both electrodes is calculated by applying the conversion factor CF (in the reciprocal of the same root dimensional unit of that area, or mm) to arrive at a gap distance Lg of about 100 μm. -1 In another example where the area of ​​one electrode is 0.24 square mm, the conversion factor CF (the reciprocal of the same root dimensional unit or mm -1 ) is 1.25mm -1 or less, giving a range of minimum gap distance Lg from about 300 μm to about 24 μm. Regardless of electrode shape, the preferred conversion factor CF (inverse of the same root dimensional unit to electrode area) is about 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 electrocardiogram signals (e.g., from the atria), such that the microelectrodes (402, 404) only pick up electrocardiogram signals generated by tissue (e.g., pulmonary veins) in contact with the microelectrodes (402, 404). Figure 15 shows a graph (600) of three substantially fraction-free electrocardiogram signal plots (602, 604, 606) that represent signals picked up by microelectrodes (402, 404) constructed and arranged in accordance with the above teachings. Those skilled in the art will understand that the plots (602, 604, 606) show voltage over time as sensed by the microelectrodes in contact with tissue. By way of example only, plots 602, 604, and 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) generate far-field signals of significant amplitude, the microelectrode pairs 400 do not pick up these far-field signals due to the configuration and placement of the electrodes 402, 404 of each pair 400 as described above. Instead, plots 602, 604, and 606 show only the electrical potentials from the relevant regions of the pulmonary veins themselves.

[0051] Because these plots (602, 604, 606) in FIG. 15 do not include the types of fractions of plots (502, 504, 506) shown in FIG. 14, a physician may be able to more easily annotate the timing of the wavefront and perform better diagnosis of the wavefront's direction, source, and cycle length to determine the specific location within the tissue associated with the abnormal electrical signal; thereby more reliably and accurately identifying the appropriate location for treatment (e.g., ablation, etc.). It should be understood that the improvement of the electrocardiogram signal in FIG. 15 over that of FIG. 14 is solely due to the configuration and placement of the electrodes (402, 404) of each pair (400) as described above. In this example, the improvement of the electrocardiogram signal in FIG. 15 over that of FIG. 14 is not due to the use of signal filtering algorithms or other signal processing techniques.

[0052] III. Illustrative Combinations The following examples illustrate various, non-exhaustive, ways in which the teachings herein can be combined or applied. It should be understood that the following examples are not intended to limit the scope of any claims that may be presented at any time in this application or any subsequent application of this application. No disclaimer is intended. The following examples are provided for illustrative purposes only. It is contemplated that the various teachings herein may be arranged and applied in many other ways. It is also contemplated that some variations may omit certain features referred to in the following examples. Accordingly, none of the aspects or features referred to below should be considered critical unless later expressly indicated by the inventor or the inventor's successor in interest. If any claims are filed in this application or any subsequent application related to this application that include additional features other than those referred to below, those additional features shall not be presumed to have been added for any reasons related to patentability.

[0053] Example 1 1. A device comprising: (a) a shaft; and (b) an end effector at a distal end of the shaft, the end effector sized to fit within an anatomical passageway within a subject's cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair including (i) a first electrode having a first surface area in square dimensional units and (ii) a second electrode having a first surface area, the first electrode and the second electrode being spaced apart from each other by a gap distance, the gap distance being defined by multiplying the first surface area by a conversion factor in the range of about 0.1 to about 2, where the conversion factor is the reciprocal of the square root of the same dimensional units as the first surface area.

[0054] Example 2 2. The device of 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 device of example 2, wherein the shaft defines a longitudinal axis, the spines extend outwardly away from the longitudinal axis, and the spines have respective free ends oriented away from the longitudinal axis.

[0056] Example 4 The device of example 2, wherein the spines are configured to bow outward and converge distally to form a basket configuration.

[0057] Example 5 The device of example 2, wherein the end effector further includes an expandable member, and the spine is secured to an outer surface of the expandable member.

[0058] Example 6 The device of any one or more of Examples 1-5, wherein the first surface area comprises about 0.95 square millimeters or less.

[0059] Example 7 The device of any one or more of Examples 1-5, wherein the first surface area comprises about 0.4 square millimeters or less.

[0060] Example 8 The apparatus of any one or more of Examples 1-7, wherein the gap distance comprises any distance from about 50 μm to about 3 mm.

[0061] Example 9 The device of example 8, wherein the gap distance includes any distance from about 50 μm to about 0.5 mm.

[0062] Example 10 10. The device of any one or more of Examples 1-9, 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 on only one of the sides of the corresponding electrode support member.

[0063] Example 11 The device of any one or more of Examples 1-10, wherein the first electrode and the second electrode of each electrode pair comprise a biocompatible metal or a conductive polymer.

[0064] Example 12 12. The device of example 11, wherein the biocompatible metal comprises a metal selected from one of platinum, palladium, cobalt chromium, nitinol, gold, or any combination thereof.

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

[0066] Example 14 14. The device of any one or more of Examples 11-13, wherein the biocompatible metal is plasma treated.

[0067] Example 15 A device described in any one or more of Examples 1-14, wherein at least one electrode pair is configured to pick up electrocardiogram signals of tissue immediately adjacent to the electrode pair in contact with the electrode pair without fractionation due to far-field interactions.

[0068] Example 16 15. The device of any one or more of Examples 1-14, wherein at least one electrode pair is configured to collect an electrocardiogram signal of cardiac tissue in contact with the electrode pair, and the electrocardiogram signal collected by the electrode pair is a signal having a significantly reduced fraction during fibrillation of the cardiac tissue.

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

[0070] Example 18 17. The device of any one or more of Examples 1-16, wherein the first surface area comprises any surface area between about 0.24 square millimeters and about 0.4 square millimeters.

[0071] Example 19 The device of any one or more of Examples 1-18, wherein the end effector is sized to fit within an anatomical passageway within the human cardiovascular system.

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

[0073] Example 21 21. The device of example 20, wherein the electrode pair comprises a configuration other than a linear planar shape.

[0074] Example 22 22. The device of any one or more of Examples 20-21, wherein the first length comprises any length from about 100 μm to about 750 μm.

[0075] Example 23 22. The device of any one or more of Examples 20-21, wherein the first width comprises any width from about 800 μm to about 1 mm.

[0076] Example 24 22. The apparatus of any one or more of Examples 20-21, wherein the gap distance comprises any distance from about 50 μm to about 3 mm.

[0077] Example 25 22. The device of any one or more of Examples 20-21, wherein the first width comprises any width from about 800 μm to about 0.5 mm.

[0078] Example 26 The gap distance can be as small as 1.25 mm for an area of ​​one electrode up to 1 square millimeter. -1 26. The apparatus of any one or more of Examples 20-25, wherein the conversion factor is determined by multiplying the conversion factor by:

[0079] Example 27 The conversion factor is approximately 0.83 mm -1 27. The device of Example 26, wherein

[0080] Example 28 The conversion factor is approximately 0.2 mm -1 27. The device of Example 26, wherein

[0081] Example 29 The conversion factor is approximately 0.4 mm2 in terms of the root dimension of the electrode area. -1 27. The device of Example 26, wherein

[0082] Example 30 The conversion factor is approximately 1 mm -1 27. The device of Example 26, wherein

[0083] Example 31 The conversion factor is approximately 0.5 mm -1 27. The device of Example 26, wherein

[0084] Example 32 32. The device of any of Examples 1-31, wherein the longitudinal axis comprises a longitudinal axis defined by the two nearest substantially parallel surfaces of the microelectrode.

[0085] Example 33 1. A device comprising: (a) a shaft; and (b) an end effector at a distal end of the shaft, the end effector sized to fit within an anatomical passageway within the human cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair including: (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, the first electrode and the second electrode being spaced apart from each other by a gap distance defined by two nearest substantially parallel surfaces of the respective first electrode and second electrode, the gap distance (Lg) being about 1.25 mm from one of the first surface area or the second surface area. -1 Device, including any value from the product with the following conversion factor:

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

[0087] Example 35 35. The device of any one or more of Examples 33-34, wherein the first surface area comprises 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.

[0088] Example 36 The device of any one or more of Examples 33-35, wherein the gap distance (Lg) comprises any distance from about 50 μm to about 500 μm.

[0089] Example 37 36. The apparatus of any one or more of Examples 33-35, wherein the gap distance comprises any distance from about 100 μm to about 200 μm.

[0090] Example 38 38. The device of any one or more of Examples 33-37, wherein the first electrode and the second electrode comprise substantially identical curved planar configurations.

[0091] Example 39 38. The device of any one or more of Examples 33-37, wherein the first electrode and the second electrode comprise a substantially identical linear planar configuration.

[0092] Example 40 40. The device of any one or more of Examples 33-39, wherein the first width and the gap distance have a ratio of about 5:1.

[0093] Example 41 1. A device comprising: (a) a shaft; and (b) an end effector at a distal end of the shaft, the end effector sized to fit within an anatomical passageway within a subject's cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair including a first electrode and a second electrode spaced apart from each other along a longitudinal axis by a gap area (Ag) located therebetween, the gap area (Ag) having a gap length (Lg) relative to the longitudinal axis, wherein: (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 less than or equal to 1.

[0094] Example 42 The device of Example 41 in combination with any one or more of Examples 2-32.

[0095] IV. Other 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 an additional electrode dedicated to providing RF ablation. Such RF ablation capabilities may be provided in accordance with the teachings of any of the various patent documents cited herein. Alternatively, RF ablation capabilities may be omitted from the end effector (15, 117, 200, 300).

[0096] It should be understood that any of the embodiments described herein may include various other features in addition to or in place of those described above. By way of example only, any of the embodiments described herein may also 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. Thus, the above-described teachings, expressions, embodiments, examples, etc. should not be viewed in isolation from one another. Various suitable ways in which the teachings herein can be combined will be readily apparent to those skilled in the art in light of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0098] While various versions of the present invention have been shown and described, further adaptations of the methods and systems described herein may be achieved by appropriate modifications by those skilled in the art without departing from the scope of the present invention. Some such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For example, the above-described embodiments, versions, geometries, materials, dimensions, ratios, steps, etc., are exemplary and not required. Accordingly, it is understood that the scope of the present invention should be considered in light of the following claims and is not limited to the details of structure and operation shown and described in this specification and drawings.

[0099] [Embodiment] (1) A device comprising: (a) a shaft; (b) an end effector at a distal end of the shaft, the end effector sized to fit within an anatomical passageway within the subject's cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair including a first electrode and a second electrode spaced apart from each other along a longitudinal axis by a gap area (Ag) located therebetween, the gap area (Ag) having a gap length (Lg) relative to the longitudinal axis; (i) the length (L) of one of the electrodes along the longitudinal axis is equal to or greater 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 device of embodiment 1, wherein the end effector further includes a plurality of elongated spines and a plurality of the electrode pairs, the electrode pairs being fixed to the spines. (3) The device described in embodiment 2, wherein the spine includes respective free ends extending along the longitudinal axis. (4) The device of embodiment 2, wherein the spine is configured to bow outward and converge distally to form a basket configuration. (5) The device of embodiment 2, wherein the end effector further includes an expandable member, and the spine is fixed to an outer surface of the expandable member.

[0100] (6) The device of any one of embodiments 1 to 5, wherein the first surface area comprises about 0.95 square millimeters or less. (7) The device of any one of embodiments 1 to 5, wherein the first surface area comprises about 0.4 square millimeters or less. (8) The device according to any one of the preceding embodiments, wherein the gap distance includes any distance between about 50 μm and about 3 mm. (9) The device of embodiment 8, wherein the gap distance includes any distance between about 50 μm and about 0.5 mm. (10) A device described in any 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 located on only one of the sides of the corresponding electrode support member.

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

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

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

[0104] (26) The gap distance is between the area of ​​one electrode and the area of ​​one electrode, and is approximately 1.25 mm -1An apparatus according to any one of embodiments 20 to 25, determined by multiplying with the following conversion factor: (27) The conversion factor is approximately 0.83 mm -1 27. The device of embodiment 26, wherein: (28) The conversion factor is approximately 0.2 mm -1 27. The device of embodiment 26, wherein: (29) The conversion factor is about 0.4 mm in root dimension of the area of ​​the electrode. -1 27. The device of embodiment 26, wherein: (30) The conversion factor is approximately 1 mm -1 27. The device of embodiment 26, wherein:

[0105] (31) The conversion factor is approximately 0.5 mm -1 27. The device of embodiment 26, wherein: (32) The device described in any one of embodiments 1 to 31, wherein the longitudinal axis comprises a longitudinal axis defined by the two nearest substantially parallel surfaces of the microelectrode. (33) An apparatus comprising: (a) a shaft; (b) an end effector at a distal end of the shaft, the end effector sized to fit an anatomical passageway within a human cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair comprising: (i) a first electrode having a first surface area of ​​about 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 respective first electrode and second electrode; The gap distance (Lg) is approximately 1.25 mm from one of the first surface area or the second surface area. -1 Device, including any value from the product with the following conversion factor: (34) The device of embodiment 33, wherein the second surface area is equal to the first surface area. (35) The device of embodiment 33 or 34, wherein the first surface area comprises 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 device according to any one of embodiments 33 to 35, wherein the gap distance (Lg) includes any distance between about 50 μm and about 500 μm. (37) The device according to any one of embodiments 33 to 35, wherein the gap distance includes any distance between about 100 μm and about 200 μm. (38) The device described in any one of embodiments 33 to 37, wherein the first electrode and the second electrode include substantially identical curved planar configurations. (39) The device described in any one of embodiments 33 to 37, wherein the first electrode and the second electrode comprise substantially the same linear planar configuration. (40) An apparatus described in any one of embodiments 33 to 39, wherein the first width and the gap distance have a ratio of approximately 5:1.

[0107] (41) An apparatus comprising: (a) a shaft; (b) an end effector at a distal end of the shaft, the end effector sized to fit an anatomical passageway within the subject's cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair comprising: (i) a first electrode having a first surface area of ​​a square dimensional unit; (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 factor in the range of about 0.1 to about 2 that is the reciprocal of the square root of the same dimensional unit as the first surface area.

Claims

1. 1. A method for manufacturing a device, comprising: (a) a shaft; (b) an end effector at a distal end of the shaft, the end effector sized to fit an anatomical passageway within the subject's cardiovascular system, the end effector including at least one electrode pair configured to contact cardiovascular tissue and thereby pick up electrocardiogram signals, each electrode pair comprising: (i) a first electrode having a first surface area of ​​a square dimensional unit; (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; determining the gap distance based on multiplying the first surface area by a conversion factor ranging from 0.1 to 2, the reciprocal of the square root of the first surface area in the same dimensional units as the first surface area.

2. The method of claim 1 , wherein the first surface area ranges from 0.05 square millimeters to 1 square millimeter.

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

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

5. 5. The method of claim 4, wherein the shaft defines a first longitudinal axis, the spines extend outwardly away from the first longitudinal axis, and the spines have respective free ends oriented away from the first longitudinal axis.

6. 2. The method of claim 1, wherein the at least one electrode pair is arranged along a second longitudinal axis, the electrodes being oriented parallel to one another and configured such that two nearest substantially parallel surfaces define the second longitudinal axis.

7. 7. The method of 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 of claim 4 , wherein the spines are configured to bow outward and converge distally to form a basket configuration.

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

10. The method of claim 9, wherein the first length comprises any length between 100 μm and 750 μm.

11. The method of claim 10, wherein the first width comprises any width between 800 μm and 1 mm.

12. The gap distance is between the first surface area and the first surface area by 1 square millimeter and 1.25 mm. －１ The method according to any one of claims 9 to 11, wherein the value is determined by multiplying the value by the following conversion factor:

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