Multidimensional acquisition of bipolar signals from catheters

Abstract

The present invention is entitled "Multi-dimensional Acquisition of Bipolar Signals from a Catheter." A medical device is disclosed that includes a probe having a basket assembly at its distal end, the basket assembly including a plurality of elastic spines having a plurality of electrodes arranged along the length of each of the spines. Processing circuitry is configured to acquire a first bipolar electrical signal from tissue between a first electrode and a second electrode, the first and second electrodes being located at first and second locations along a first spine of the basket assembly, and a second bipolar electrical signal from tissue between the first electrode and a third electrode located in a third location on a second spine of the basket assembly, and to interpolate vector electrical properties of the tissue along an axis passing through the first location and between the second location and the third location based on the first and second bipolar electrical signals.

Description

Technical Field

[0001] The present invention relates generally to invasive diagnostic methods and apparatus, and particularly to catheter-based measurement of electrophysiological signals. Background Art

[0002] In electroanatomical mapping of the heart, a catheter is inserted into a heart chamber and electrodes on the catheter contact the myocardium within the chamber to acquire electrical signals at a large number of locations. A variety of specialized catheters have been developed to facilitate this procedure, with electrode arrays extending on the distal portion of the catheter.

[0003] For example, U.S. Patent 6,748,255, the disclosure of which is hereby incorporated by reference in its entirety as if fully set forth herein, describes an improved basket catheter particularly for mapping the heart. The catheter comprises an elongated catheter body having a proximal end and a distal end and at least one lumen therethrough. A basket electrode assembly is mounted at the distal end of the catheter body. The basket assembly has a proximal end and a distal end and includes a plurality of spines connected at the proximal and distal ends thereof. Each spine includes at least one electrode. The basket assembly has an expanded arrangement in which the spines curve radially outwardly and a collapsed arrangement in which the spines are arranged generally along the axis of the catheter body.

[0004] The catheter also includes a distal position sensor mounted at or near the distal end of the basket electrode assembly, and a proximal position sensor mounted at or near the proximal end of the basket electrode assembly. In use, coordinates of the distal position sensor can be determined relative to the coordinates of the proximal sensor, while simultaneously obtaining known information about the curvature of the spines of the basket mapping assembly to locate the position of at least one electrode per spine.

[0005] A catheter with multiple electrodes can be applied to perform various diagnostic measurements. For example, U.S. Patent Application Publication 2019 / 0216346 describes a system including a catheter comprising multiple spatially distributed electrodes configured to measure electrical signals of the heart. The system is configured to determine the location of electrodes at multiple different catheter locations in the heart and includes a processing unit that maps electrical activity in the heart. The processing unit is configured to receive a measured electrical signal from each of the multiple different catheter locations and determine whether the measured electrical signal at the location is organized. If the measured electrical signal at the location is organized, the processing unit is configured to determine at least one of a velocity vector, a cycle length, and a degree of organization at the location based on the measured electrical signal. Summary of the Invention

[0006]

[0014] Embodiments of the present invention described below provide improved methods and systems for electrophysiological measurement and mapping.

[0007] Thus, according to an embodiment of the present invention, a medical device is provided that includes a probe comprising an insertion tube configured for insertion into a body cavity of a patient and a basket assembly distally connected to the insertion tube. The basket assembly includes a plurality of elastic spines having respective proximal and distal ends and comprising a plurality of electrodes arranged along the length of each of the spines between the respective proximal and distal ends. The proximal ends of the spines engage at the proximal end of the basket assembly, and the distal ends of the spines engage at the distal end of the basket assembly. When the basket assembly is deployed in a body cavity, the spines arc radially outwardly, thereby contacting the electrodes with tissue in the body cavity. Processing circuitry is configured to acquire a first bipolar electrical signal from tissue between a first electrode and a second electrode located at first and second locations along a first spine of the basket assembly, and to acquire a second bipolar electrical signal from tissue between the first electrode and a third electrode located at a third location on a second spine of the basket assembly, and to interpolate vector electrical properties of the tissue along an axis passing through the first location and between the second location and the third location based on the first and second bipolar electrical signals.

[0008] In some embodiments, the second electrode is adjacent to the first electrode on the first ridge, and the second ridge is adjacent to the first ridge. In one embodiment, of the electrodes on the second ridge, the third electrode is closest to the first electrode.

[0009] Additionally or alternatively, the processing circuit is configured to derive a longitudinal component of the vector electric characteristic from the first bipolar electrical signal and a transverse component of the vector electric characteristic from the second bipolar signal. In a disclosed embodiment, the processing circuit is configured to find the magnitude and direction of the vector electric characteristic by calculating a vector sum of the longitudinal component and the transverse component.

[0010] In one embodiment, the first bipolar signal and the second bipolar signal are generated by an electro-activation wave passing through the tissue, and the vector electrical characteristic comprises a velocity of the electro-activation wave. Alternatively or additionally, the vector electrical characteristic comprises a simulated bipolar electrical signal between the first location and a fourth location on an axis passing through the first location and between the second location and the third location.

[0011] In some embodiments, the processing circuit is configured to map the vector electrical characteristics over an area of ​​tissue contacted by the electrodes on the basket assembly. Typically, the apparatus includes one or more positioning sensors coupled to the probe and configured to output positioning signals indicative of the positioning of the basket assembly, wherein the processing circuit is configured to process the positioning signals to find position coordinates of the first position, the second position, and the third position and to apply the position coordinates in mapping the vector electrical characteristics.

[0012] In a disclosed embodiment, the insertion tube comprises a flexible catheter configured for insertion into a chamber of a patient's heart, and the electrodes are configured to sense electrical potentials in myocardial tissue within the chamber.

[0013] According to an embodiment of the present invention, a method for medical diagnosis is also provided, comprising: providing a probe configured for insertion into a body cavity of a patient and comprising a basket assembly, the basket assembly comprising a plurality of elastic ridges having respective proximal and distal ends and including a plurality of electrodes arranged along the length of each of the ridges between the respective proximal and distal ends. The proximal ends of the ridges engage at the proximal end of the basket assembly, and the distal ends of the ridges engage at the distal end of the basket assembly. When the basket assembly is deployed in the body cavity, the ridges arc radially outwardly, thereby contacting the electrodes with tissue in the body cavity. A first bipolar electrical signal is acquired in tissue between a first electrode and a second electrode, the first and second electrodes being located at first and second locations along a first ridge of the basket assembly. A second bipolar electrical signal is acquired in tissue between the first electrode and a third electrode located at a third location on a second ridge of the basket assembly. Vector electrical properties of the tissue are interpolated based on the first and second bipolar signals along an axis passing through the first location and between the second and third locations.

[0014] The present invention will be more fully understood through the following detailed description of embodiments of the present invention in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic illustration of a system for electroanatomical mapping according to an embodiment of the present invention;

[0016] Figure 2 is a schematic side view of a basket catheter according to an embodiment of the present invention; and

[0017] Figure 3 The flowchart schematically illustrates a method for acquiring and processing electrophysiological signals according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] Basket-shaped catheters are used to rapidly collect large amounts of electrical data from tissue within body cavities, and in particular from myocardial tissue in the heart chambers. The measurements typically made using such catheters are bipolar measurements of the electrical potential in the tissue, acquired between adjacent electrodes on a given ridge. These bipolar measurements provide, among other things, an indication of the propagation of electrical activation waves through the tissue. However, using this approach, only the component of propagation parallel to the ridges can be measured, and the component perpendicular to the ridges can be missed.

[0019] Embodiments of the invention described herein provide a solution to this problem that enables a basket catheter to be used to measure vector electrical properties of tissue along axes that are angled relative to the spine (i.e., perpendicular and oblique angles relative to the longitudinal axis of the spine). These properties may include, for example, the directional velocity of local activation waves in the tissue and simulated bipolar signals between an electrode on one of the spines and a location where no physical electrode is present.

[0020] In the disclosed embodiments, processing circuitry associated with the basket catheter achieves these capabilities by acquiring bipolar signals from electrode pairs on the same spine and from electrode pairs on different (typically, but not necessarily, adjacent) spines. The different electrode pairs can be selected to optimize the acquired bipolar signals in terms of amplitude and direction. Despite the constraints imposed by the structure of the basket assembly, by combining bipolar signals between an electrode and its neighboring electrodes along the spine, as well as between an electrode and its neighboring electrodes on adjacent spines, the processing circuitry is able to emulate the operation of an omnidirectional bipolar probe.

[0021] In embodiments described herein, a medical device includes a probe comprising an insertion tube configured for insertion into a body cavity of a patient. A basket assembly distally connected to the insertion tube includes a plurality of elastic spines, wherein a plurality of electrodes are arranged along the length of each of the spines. The proximal ends of the spines engage at the proximal end of the basket assembly, and the distal ends of the spines engage at the distal end of the basket assembly, such that when the basket assembly is deployed in the body cavity, the spines arc radially outward. The electrodes thereby contact tissue in the body cavity.

[0022] Processing circuitry, such as a programmable processor in the device, acquires a first bipolar electrical signal from tissue between a first electrode and a second electrode along a first spine of the basket assembly, and a second bipolar electrical signal from tissue between the first electrode on the first spine and a third electrode on the second spine of the basket assembly. The processing circuitry can then interpolate a vector electrical characteristic of the tissue based on the first and second bipolar signals. In some cases, the vector electrical characteristic will be oriented longitudinally along the spine or transversely between the first and third electrodes. However, more generally, the vector electrical characteristic will have both a longitudinal component and a transverse component and will therefore be oriented along an axis passing through the location of the first electrode and between the locations of the second and third electrodes.

[0023] The embodiments described below relate specifically to a basket catheter for sensing electrical potentials in myocardial tissue in a chamber of the heart. However, the principles of the invention may be similarly applied to perform other types of electrophysiological measurements in other body cavities.

[0024] Now see Figure 1 and Figure 2, which schematically illustrates an electroanatomical mapping system 20 using a basket catheter 22 according to an embodiment of the present invention. Figure 1 is a diagrammatic view of the system as a whole, and Figure 2 Details of the basket assembly 40 at the distal end of the catheter 22 are shown. The elements of the system 20 may be based on the basket assembly 40 manufactured by Biosense Webster, Inc. (Irvine, California). Components of the system.

[0025] Physician 30 navigates catheter 22 to deploy basket assembly 40 at a target location within a chamber of heart 26 of patient 28. Basket assembly 40 is distally connected to insertion tube 25, which physician 30 manipulates using manipulator 32 near the proximal end of catheter 22. Basket assembly 40 is inserted in a collapsed configuration through the vasculature of patient 28 through sheath 23 into the heart chamber to be mapped, then deployed from the sheath and allowed to expand within the chamber. By containing basket assembly 40 in this collapsed configuration, sheath 23 also serves to minimize vascular trauma along the way to the target location.

[0026] As in Figure 2 As can be seen in the figure, the basket assembly 40 includes a plurality of resilient spines 55, with a plurality of electrodes 48 arranged along the length of each of the spines. The spines 55 typically comprise, for example, a suitable resilient metal or plastic material. The proximal ends of the spines 55 meet at the proximal end of the basket assembly, which is connected to the distal end of the insertion tube 25. The distal ends of the spines 55 also meet at the distal end of the basket assembly. When the basket assembly 40 is deployed from the sheath 23 into the heart chamber, the spines arch radially outward. The physician 30 then manipulates the catheter 22 so that the electrodes 48 contact the myocardial tissue in the heart chamber. The basket assembly 40 may also include other components (not shown), such as an ultrasound transducer, a contact force sensor, and a temperature sensor. The electrodes 48 and these other components are connected to wires (not shown) that extend through the insertion tube 25 to the proximal end of the catheter 22, where these wires are connected to processing circuitry in the console 24.

[0027] The catheter 22 includes one or more positioning sensors that output positioning signals indicative of the positioning (position and orientation) of the basket assembly 40. Figure 2In the illustrated embodiment, the basket assembly 40 includes a magnetic sensor 50 located at the distal end of the insertion tube 25, or in other words, at the proximal end of the basket assembly. A second magnetic sensor 52 is secured to the distal end of the basket assembly. Alternatively, the basket assembly 40 may include only a single magnetic sensor, or may include two or more magnetic sensors located at different locations on the basket assembly. The magnetic sensors 50 and 52 typically include, for example, miniature coils or Hall effect devices that output electrical signals in response to an applied magnetic field. Similar to the electrodes 48, the magnetic sensors 50 and 52 are connected to the console 24 via wires extending through the insertion tube 25.

[0028] The patient 28 is placed in a magnetic field generated by a magnetic field generator coil 42, which is driven by a drive circuit 43 in the console 24 to generate a plurality of magnetic field components oriented along different respective axes. During navigation of the basket assembly 40 in the heart 26, the magnetic sensors 50, 52 output signals in response to these magnetic field components. Position sensing circuitry (such as the processor 41 in the console 24) receives these signals via the interface circuit 44 and processes them to find the position coordinates and orientation coordinates of the basket assembly 40 and, thereby, each of the electrodes 48. The interface circuit 44 includes suitable analog amplifiers and filters, as well as analog / digital converters, for processing the signals output by the two sensors 50, 52 and the electrodes 48 and inputting corresponding digital values ​​to the processor 41.

[0029] The method and apparatus for magnetic position sensing implemented in the system 20 are based on the above The methods and apparatus used in the system. The operating principles of this magnetic sensing are described in detail in, for example, U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455 A1, 2003 / 0120150 A1, and 2004 / 0068178 A1, the disclosures of which are hereby incorporated by reference in their entirety as if fully set forth in the Appendix. Alternatively, system 20 may implement other magnetic position sensing techniques known in the art.

[0030] Alternatively or in addition, system 20 may apply other position sensing techniques to find the coordinates of electrodes 48 on basket assembly 40. For example, processor 41 may sense the impedance between electrodes 48 and body surface electrodes 49 applied to the chest of patient 28 and may convert the impedance into position coordinates using techniques known in the art. Using the above-described measured impedance from electrodes 48, the position of electrodes 48 may be determined using, for example, CARTO sensors manufactured by Biosense-Webster (Irvine, California). TM The method is determined by a system and is described in detail in U.S. Patents 7,756,576, 7,869,865, 7,848,787, and 8,456,182, the disclosures of which are incorporated herein by reference and copies are provided in the Appendix. This method is sometimes referred to as advanced catheter positioning (ACL). In this case, the electrode 48 itself serves as the positioning sensor for the ACL.

[0031] The processor 41 uses the spatial and electrophysiological signals it receives via the interface circuit 44 to construct an electroanatomical map 31 of the heart chamber in which the basket assembly 40 is deployed. During and / or after the procedure, the processor 41 may plot the electroanatomical map 31 to the display 27. Figure 1 In the illustrated embodiment, the processor 41 overlays one or more icons 33 that indicate vector electrical properties of the myocardial tissue that the processor derives from the bipolar electrical signals it receives from the basket assembly 40. Techniques that may be applied by the processor to derive such vector properties are described further below.

[0032] In some embodiments, the processor 41 comprises a general-purpose computer having suitable interface circuits 44 for receiving signals from the catheter 21 (including a low noise amplifier and an analog / digital converter), and for receiving signals from other components of the system 20 and controlling the operation of these other components. The processor 41 typically performs these functions under the control of software stored in a memory 48 of the system 20. The software can be downloaded to the computer in electronic form over a network, for example, or it can be alternatively or additionally provided and / or stored on a non-transitory tangible medium (such as a magnetic memory, an optical memory, or an electronic memory). Specifically, the processor 41 runs a dedicated algorithm that enables the processor to perform the signal acquisition and processing methods described below. In addition or alternatively, at least some of the functions of the processor 41 can be performed by dedicated or programmable hardware logic components.

[0033] Figure 1 The system configuration shown is chosen by way of example for the sake of conceptual clarity. Figure 1Only the elements of system 20 that are specifically relevant to the technology disclosed herein are shown. The remaining elements of the system will be apparent to those skilled in the art, who will also understand that the principles of the present invention can be implemented in other medical diagnostic systems using other components. All such alternative implementations are considered to be within the scope of the present invention.

[0034] Figure 3 1 is a flow chart schematically illustrating a method for collecting and processing electrophysiological signals according to an embodiment of the present invention. For the sake of clarity and brevity, the method refers to the elements of system 20 and specifically to the following: Figure 2 The method is described with reference to the basket assembly 40 shown. The method is described with reference to the basket assembly 40 shown. Figure 1 ) is applied to derive the vector electrical properties of the myocardial tissue contacted by the basket assembly. However, as described above, other specific implementations of the principles of this method are also considered to be within the scope of the present invention.

[0035] At a first bipolar acquisition step 60, processor 41 acquires a first bipolar electrical signal from the myocardial tissue between adjacent electrodes 48a and 48b on first ridge 55a. Alternatively, electrodes 48a and 48b may be spread out at a greater distance along ridge 55a. The locations of electrodes 48a and 48b in contact with the myocardial tissue define a longitudinal axis 56 that extends along a portion of ridge 55a.

[0036] At a second bipolar acquisition step 62, processor 41 also acquires a second bipolar electrical signal between electrode 48a and electrode 48c located on adjacent ridge 55b. Alternatively, ridge 55b may not be adjacent to ridge 55a, provided that both ridges are in contact with myocardial tissue. Electrode 48c may conveniently be selected as the electrode on ridge 55b that is closest to electrode 48a. The positions of electrodes 48a and 48c define a transverse axis 58 that is perpendicular to or obliquely oriented relative to longitudinal axis 56. Alternatively or in addition, processor 41 may acquire a bipolar electrical signal between electrode 48a and other electrodes on ridge 55b or other ridges.

[0037] Based on the bipolar electrical signals acquired at steps 60 and 62, the processor 41 calculates the vector components of the electrical potential propagating in the myocardial tissue at a component calculation step 64. In this example, the processor calculates the components of the activation wave, which include a longitudinal (AB) component along axis 56 and a transverse (AC) component along axis 58. These directional components are derived from the bipolar signals acquired at steps 60 and 62, respectively. At a vector calculation step 66, the processor 41 interpolates between these components to find the magnitude and direction of the activation vector. The result is a vector sum, where the direction extends between the positions of electrodes 48b and 48c, for example, along an inclined axis 59 that passes through the position of electrode 48a, as shown in FIG. Figure 2 shown.

[0038] This vector sum represents the local directional velocity of the electrical activation wave in the myocardial tissue at the location of electrode 48a. The processor 41 typically makes similar measurements at other electrode locations on the basket assembly 40 using bipolar electrodes along and between the ridges 55. The processor is thus able to generate a map 31 (e.g., Figure 1 ), the map includes icons 33 representing activation velocity and other vector electrical characteristics.

[0039] Alternatively or in addition, processor 41 may generate and display vector electrical properties in the form of simulated bipolar electrical signals based on the bipolar signals acquired at steps 60 and 62, respectively. For example, processor 41 may generate such simulated signals between electrode 48a and a "virtual electrode" located at a position on axis 59. The magnitude of these simulated bipolar signals may be calculated with or without calculating the corresponding direction. In one embodiment, the magnitude of the simulated bipolar signal at any given point is simply approximated as the sum of the amplitudes of the bipolar signals acquired at steps 60 and 62, respectively. As used herein, the term "vector electrical properties" includes any electrical signal generated by an organ tissue (e.g., a heart) where physical properties (e.g., volts or amperes) and directional properties can be derived from such signals acquired by a given electrode 48. As previously described, such properties may include the directional velocity of a local activation wave in the tissue measured by electrode 48, as well as a simulated bipolar signal between an electrode on one of the ridges and a location where no physical electrode exists.

[0040] It should be understood that the above embodiments are cited by way of example only, and the present invention is not limited to what has been specifically shown and described hereinabove. On the contrary, the scope of the present invention includes combinations and subcombinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art.

Claims

1. A medical device comprising: A probe, comprising: an insertion tube configured for insertion into a body cavity of a patient; and a basket assembly distally connected to the insertion tube and comprising a plurality of resilient spines having respective proximal and distal tips and comprising a plurality of electrodes arrayed along the length of each of the spines between the respective proximal and distal tips, causing the proximal tips of the spines to engage at a proximal end of the basket assembly and the distal tips of the spines to engage at a distal end of the basket assembly, and when the basket assembly is deployed in the body cavity, the spines to bow radially outwardly whereby the electrodes contact tissue in the body cavity; and processing circuitry configured to acquire a first bipolar electrical signal from the tissue between a first electrode and a second electrode, the first electrode and the second electrode being located at first and second locations along a first spine of the basket assembly, and a second bipolar electrical signal from the tissue between the first electrode and a third electrode located in a third location on the second spine of the basket assembly, a first axis between the first electrode and the third electrode extending at an oblique angle relative to a second axis extending between the first electrode and the second electrode, and interpolate vector electrical properties of the tissue along a third axis passing through the first location and between the second location and the third location based on the first and second bipolar electrical signals. 2 . The device of claim 1 , wherein the second electrode is adjacent to the first electrode on the first ridge, and the second ridge is adjacent to the first ridge. 3 . The device of claim 2 , wherein among the electrodes on the second ridge, the third electrode is closest to the first electrode. 4 . The apparatus of claim 1 , wherein the processing circuit is configured to derive a longitudinal component of the vector electrical characteristic from the first bipolar electrical signal and to derive a transverse component of the vector electrical characteristic from the second bipolar signal. 5 . The apparatus of claim 4 , wherein the processing circuit is configured to find the magnitude and direction of the vector electrical characteristic by calculating a vector sum of the longitudinal component and the transverse component.

6. The apparatus of claim 1 , wherein the first and second bipolar signals are generated by electro-activation waves passing through the tissue, and the vector electrical characteristic comprises a velocity of the electro-activation waves.

7. The apparatus of claim 1, wherein the vector electrical characteristic comprises an analog bipolar electrical signal between the first location and a fourth location on the third axis, the third axis passing through the first location and between the second location and the third location.

8. The apparatus of claim 1, wherein the processing circuit is configured to map the vector electrical characteristic over a region of the tissue contacted by the electrode on the basket assembly.

9. The apparatus of claim 8 , and comprising one or more positioning sensors connected to the probe and configured to output positioning signals indicative of the positioning of the basket assembly, wherein the processing circuit is configured to process the positioning signals to find position coordinates of the first position, the second position, and the third position and to apply the position coordinates in mapping the vector electrical properties.

10. The apparatus of claim 1, wherein the insertion tube comprises a flexible catheter configured for insertion into a chamber of the patient's heart, and the electrodes are configured to sense electrical potentials in myocardial tissue within the chamber.

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