Determining elongation of expandable distal end of catheter

Abstract

The invention relates to determining elongation of an expandable distal end of a catheter. A system includes an expandable distal end assembly, a proximal position sensor, a distal position sensor, and a processor. The expandable distal end assembly is coupled to a distal end of a shaft for insertion into a lumen of a patient organ. A proximal position sensor and a distal position sensor are located at a proximal end and a distal end of the distal end assembly, respectively. The processor is configured to estimate a position and a longitudinal direction of the proximal sensor and a position of the distal sensor, all in a coordinate system used by the processor. The processor is further configured to project the estimated position of the distal sensor on an axis defined by the estimated longitudinal direction, and to calculate an elongation of the distal end assembly by calculating a distance between the estimated position of the proximal sensor and the projected position of the distal sensor.

Description

Technical Field

[0001] The present invention relates generally to invasive medical probes and, in particular, to cardiac catheters. Background Art

[0002] Tracking the shape of an in vivo object such as a catheter is known in the patent literature. For example, U.S. Pat. No. 6,748,255 describes an improved basket catheter that is particularly useful for mapping the heart. The catheter includes an elongated catheter body having a proximal end and a distal end and at least one lumen passing 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 ridges connected at its proximal and distal ends. Each ridge includes at least one electrode. The basket assembly has an expanded arrangement in which the ridges are curved radially outwardly, and a collapsed arrangement in which the ridges are arranged generally along the axis of the catheter body. 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, the coordinates of the distal position sensor relative to the coordinates of the proximal sensor may be determined while acquiring known information about the curvature of the spines of the basket mapping assembly in order to find the position of at least one electrode per spine.

[0003] As another example, U.S. Patent Application Publication No. 2013 / 0123694 describes a method for measuring a balloon expansion profile in vivo. The method includes providing a balloon having at least one sensing element as a diagnostic device, wherein the at least one sensing element is characterized by at least one attribute representing the size of the balloon; measuring the at least one attribute to obtain an observed attribute value; and estimating the balloon size and the balloon expansion profile based on the observed attribute value. A diagnostic kit for measuring the balloon expansion profile in vivo is also provided. The diagnostic kit includes a diagnostic device; a measurement module for measuring the observed attribute value of the attribute; and a processor module for processing the observed attribute value to estimate the balloon expansion profile as one or more outputs.

[0004] U.S. Patent Application Publication No. 2011 / 0313414 describes a method for simulating the curved shape of a catheter, the method comprising providing at least two sensor elements in the catheter, wherein the sensor elements cross magnetic field lines to generate induced currents, extracting spatial information of the sensor elements from the induced current information, and calculating the curved shape of the catheter based on the spatial information combined with characteristic information of the catheter. Summary of the invention

[0005] An embodiment of the present invention provides a system comprising an expandable distal end assembly, a proximal position sensor, a distal position sensor, and a processor. The expandable distal end assembly is connected to the distal end of an axis for insertion into a cavity of a patient's organ. The proximal position sensor is located at the proximal end of the distal end assembly. The distal position sensor is located at the distal end of the distal end assembly. The processor is configured to estimate the position and longitudinal direction of the proximal sensor in a coordinate system used by the processor based on a signal received from the proximal position sensor, and to estimate the position of the distal position sensor in the coordinate system based on a signal received from the distal position sensor. The processor is further configured to project the estimated position of the distal position sensor onto an axis defined by the estimated longitudinal direction, and to calculate the elongation of the distal end assembly by calculating the distance between the estimated position of the proximal position sensor and the projected position of the distal position sensor.

[0006] In some embodiments, the proximal position sensor and the distal position sensor are magnetic sensors.

[0007] In some embodiments, using the calculated elongation, the processor is further configured to estimate the ellipticity of the expandable distal tip assembly.

[0008] In one embodiment, the expandable distal tip assembly comprises a basket. In another embodiment, the expandable distal tip assembly comprises a balloon.

[0009] In some embodiments, the processor is configured to indicate an elongation of the expandable distal tip assembly based on the calculated elongation.

[0010] According to an embodiment of the present invention, a method is also provided, the method comprising receiving signals from a proximal position sensor and a distal position sensor in a processor, the proximal position sensor being located at the proximal end of an expandable distal end assembly, the expandable distal end assembly being connected to the distal end of an axis for insertion into a cavity of a patient's organ, and the distal position sensor being located at the distal end of the distal end assembly. Based on the signal received from the proximal position sensor, the position and longitudinal direction of the proximal position sensor in a coordinate system used by the processor are estimated. Based on the signal received from the distal position sensor, the position of the distal position sensor in the coordinate system is estimated. The estimated position is projected onto an axis defined by the estimated longitudinal direction. The elongation of the distal end assembly is calculated by calculating the distance between the estimated position of the proximal sensor and the projected position of the distal position sensor.

[0011] According to an embodiment of the present invention, a system is also provided, which includes an expandable distal end, a proximal position device, a distal position device and a processor. The expandable distal end assembly is connected to the distal end of an axis for insertion into a cavity of a patient's organ. The proximal position device is located at the proximal end of the distal end assembly. The distal position device is located at the distal end of the distal end assembly, and one of the position devices is configured as a transmitter and the other is configured as a receiver. The processor is configured to estimate the distance from the receiver to the transmitter based on a signal received from the receiver, and indicate the elongation of the expandable distal end assembly as a calibration distance.

[0012] According to an embodiment of the present invention, a method is also provided, the method comprising transmitting a signal between a proximal position device located at the proximal end of an expandable distal tip assembly and a distal position device located at the distal end of a distal tip assembly, the expandable distal tip assembly being coupled to the distal end of a shaft for insertion into a cavity of a patient's organ, wherein one of the position devices is configured as a transmitter and the other is configured as a receiver. Based on the transmitted signal received from the receiver, the distance from the receiver to the transmitter is estimated. The elongation of the distal tip assembly catheter is indicated as a calibration distance.

[0013] 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

[0014] Figure 1 is a schematic illustration of a system for electroanatomical mapping according to an embodiment of the present invention, the system comprising a basket catheter;

[0015] Figure 2 According to an embodiment of the present invention Figure 1 A schematic side view of a basket catheter of ; and

[0016] Figure 3 is a flow chart schematically illustrating a method and algorithm for estimating basket catheter elongation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] Overview

[0018] An expandable distal tip assembly of a catheter for insertion into a lumen of an organ of a patient, such as a basket or balloon catheter, can be used in a variety of clinical applications, such as electroanatomical mapping and ablation of a lumen wall (e.g., a cardiac chamber wall). Deployment of the expandable distal tip assembly, which is coupled to the distal end of a shaft for insertion, is typically accomplished manually. Accurate measurements of the shape of the expandable distal tip assembly within the lumen, such as the ellipticity of the basket or balloon, are difficult to obtain because there is little (e.g., indirect) indication of whether the expandable distal tip assembly has fully expanded within the lumen (e.g., the elongation of the expandable distal tip assembly).

[0019] For example, when the ellipticity of the basket is not known, measurements that rely on a known ellipticity may produce distorted results. For example, signals from an ultrasound transducer mounted on a plurality of expandable spines of the basket may be incorrectly calibrated and may cause the processor to produce a distorted anatomical map of the cavity due to an incorrectly assumed basket ellipticity (e.g., resulting in an error in the assumed relative position and orientation of the ultrasound transducer).

[0020] As another example, when using a balloon catheter, it is important to know whether the balloon is fully expanded, fully collapsed, or in some intermediate state before taking actions such as performing an ablation, inflating the balloon, or retracting it into a sheath.

[0021] Embodiments of the invention described hereinafter provide tracking systems and methods for estimating the elongation of an expandable distal tip assembly, according to which the shape of the expandable distal tip assembly, and therefore the relative position and orientation of a device mounted, for example, on an expandable spine of the expandable distal tip assembly, can be more accurately estimated by a processor. As described below, one disclosed embodiment incorporates an estimation error correction technique using projection.

[0022] In some embodiments, the tracking system tracks an expandable distal tip assembly of the catheter, the expandable distal tip assembly including a proximal position and orientation sensor located at the proximal end of the expandable distal tip assembly and a distal position sensor located at the distal end of the expandable distal tip assembly. The processor is configured (e.g., programmed) to estimate the position and longitudinal orientation of the proximal sensor in a coordinate system used by the tracking system based on signals received from the proximal position sensor.

[0023] Based on signals received from the distal position sensor, the processor estimates a position of the distal sensor in the coordinate system and, to reduce an estimated error in the position, corrects the estimated position of the distal sensor by projecting the estimated position onto an axis defined by the estimated longitudinal direction.

[0024] The processor then calculates the elongation of the expandable distal tip assembly (e.g., a basket or balloon catheter) by calculating the distance between the estimated position of the proximal sensor and the projected position of the distal sensor. Based on the calculated elongation, the processor estimates, for example, the ellipticity of the basket and / or the elongation state of the basket or balloon.

[0025] In one embodiment, the proximal and distal sensors are magnetic sensors. The sensors are provided by a catheter-based tracking system, such as (manufactured by Biosense-Webster of Irvine, California). In another embodiment, two position devices are provided, one of which is located at the proximal end of the expandable distal tip assembly and the other of which is located at the distal end of the distal tip assembly. One of the position devices is configured as a transmitter and the other is configured as a receiver. Based on the signal received from the receiver and based on the effective calibration of the distance between the position devices as a function of the received signal, the processor estimates the distance between the receiver sensor and the transmitter sensor. The processor then provides the elongation of the expandable distal tip assembly as the estimated calibration distance.

[0026] Typically, the processor is programmed with software containing specific algorithms that enable the processor to perform each of the processor-related steps and functions listed above.

[0027] The disclosed systems and methods for determining the elongation of an expandable distal tip assembly of a catheter by using projections of the interior of a lumen of an organ may improve the diagnostic and / or therapeutic outcomes of catheterization procedures performed using an expandable distal tip assembly catheter.

[0028] System Description

[0029] Figure 1 is a schematic illustration of an electroanatomical mapping system 20 according to one embodiment of the present invention. A physician 30 navigates a basket catheter 40 (manufactured by Biosense-Webster), shown in detail in inset 45, to a target location in a heart 26 of a patient 28 by manipulating the shaft 22 and / or deflection of the slave sheath 23 using a manipulator 32 near the proximal end of the catheter. In the embodiment seen in inset 25, the physician 30 uses the catheter 40 to perform electroanatomical mapping of a cardiac chamber.

[0030] By way of example only, the embodiments described herein are primarily directed to basket-type distal tip assemblies. In alternative embodiments, the disclosed techniques may be used to estimate the elongation (and therefore the degree of expansion) of a balloon-based distal tip assembly or any other suitable type of expandable distal tip assembly.

[0031] The catheter 40 is inserted through the sheath 23 in a collapsed configuration, and the catheter 40 resumes its intended functional shape only after the catheter exits the sheath 23. By containing the catheter 40 in a collapsed configuration, the sheath 23 also serves to minimize vascular trauma on its way to the target site.

[0032] The basket catheter 40 incorporates a magnetic sensor 50A (see inset 45) at the distal edge of the shaft 22 (i.e., at the proximal edge of the basket catheter 40). Typically, although not necessarily, the sensor 50A is a three-axis sensor (TAS). A second magnetic sensor 50B is included in the distal edge of the basket catheter. The sensor 50B can be, for example, a single-axis sensor (SAS) or a three-axis sensor (TAS).

[0033] The catheter 40 further includes a plurality of expandable spines 55, which may be mechanically flexible, with one or more devices 48 coupled to each expandable spine. The devices 48 may be of various types, such as sensing electrodes, ablation electrodes, ultrasound transducers, contact force sensors, irrigation ports, temperature sensors, etc. The magnetic sensors 50A and 50B and the devices 48 are connected to various drive circuits in the console 24 via wires passing through the shaft 22. Alternatively, as described above, the catheter 40 may be an inflatable balloon.

[0034] In some embodiments, the system 20 includes a magnetic sensing subsystem to estimate the ellipticity of the basket catheter 40 and its extended / retracted state inside the chamber of the heart 26 by estimating the elongation of the basket catheter 40 from the distance between sensors 50A and 50B. The patient 28 is placed in a magnetic field generated by a pad containing a magnetic field generator coil 42, which is driven by a unit 43. The magnetic field generated by the coil 42 generates a signal indicative of position and / or direction in the sensors 50A and 50B. The generated signal is transmitted to the console 24 and becomes a corresponding electrical input to the processor 41. The processor uses the signal to calculate the elongation of the basket catheter 40 and estimates the ellipticity and the extended / retracted state of the basket based on the calculated distance between sensors 50A and 50B.

[0035] Position and / or orientation sensing methods using external magnetic fields and magnetic sensors (such as 50A and 50B) are implemented in various medical applications, such as in the CARTO TMThe invention is implemented in the system and is described in detail in 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 Publications 2002 / 0065455 A1, 2003 / 0120150 A1 and 2004 / 0068178 A1, the disclosures of which are incorporated herein by reference and attached in the Appendix.

[0036] A processor 41, typically a general purpose computer, is further connected via suitable front end and interface circuitry 44 to receive signals from surface electrodes 49. Processor 41 is connected to surface electrodes 49 by wires extending through cable 39 to the chest of patient 28.

[0037] In one embodiment, processor 41 additionally receives various spatial and electrophysiological signals via electrical interface 44 and uses information contained in these signals to construct electroanatomical map 31 of the cavity. Processor 41 may display electroanatomical map 31 on display 27 during and / or after the procedure.

[0038] The processor 41 is typically programmed in software by one skilled in the art to perform the functions described herein. The software may be downloaded to a computer in electronic form via a network, for example, or it may alternatively or additionally be disposed 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 41 to perform the steps disclosed in the present invention, as described below.

[0039] Figure 1 The illustrative examples shown in are chosen purely for the sake of conceptual clarity. Figure 1 Only elements related to the technology disclosed in the present invention are shown. System 20 generally includes additional modules and elements that are not directly related to the technology disclosed in the present invention and thus the additional modules and elements are not directly related to the technology disclosed in the present invention. Figure 1 The elements of system 20 and the methods described herein may further be applied to, for example, control ablation of tissue of heart 26 .

[0040] Using projections to determine the elongation of basket catheters

[0041] Figure 2 According to an embodiment of the present invention Figure 1Schematic side view of a basket catheter 40. The expandable frame of the basket catheter 40 includes a plurality of expandable ridges 55 near the location of the proximal position and direction sensor 50A, which is coupled to the distal end of the shaft 22. The expandable frame of the basket catheter 40 extends along the longitudinal axis 62 and converges at the distal end of the basket (the location of the distal position sensor 50B).

[0042] The spines 55 form an ellipsoidal shape for the basket, such as a shape defined by a curved surface of revolution about the longitudinal axis 62. In general, however, the basket and devices mounted on the spines need not have perfect rotational symmetry.

[0043] Based on the signal from sensor 50A, processor 41 estimates longitudinal direction 62 (i.e., a direction parallel to the longitudinal axis defined by the distal end of shaft 22). At the same time, processor 41 may erroneously estimate the position of distal sensor 50B as position 50C. Obviously, such an error would result in a distortion of the estimated shape of the basket. This error is substantially corrected by processor 41 projecting the coordinates of incorrect position 50C onto axis 62 to obtain a more accurate projected position 50D. Based on the distance between positions 50A and 50D along axis 62, the processor derives actual values ​​for elongation and ellipticity.

[0044] In another embodiment, the proximal sensor 50A is replaced by a position device configured as a transmitter, and the distal sensor 50B is replaced by a position device configured as a receiver. Based on the signal received from the receiver, and based on the effective calibration of the distance between the position devices as a function of the received signal, the processor estimates the distance between the receiver sensor and the transmitter. The processor then provides the elongation of the basket as the estimated calibration distance.

[0045] In general, a method is provided that includes transmitting a signal between a proximal position device at a proximal end of an expandable basket and a distal position device at a distal end of the basket, the expandable basket being coupled to the distal end of a shaft for insertion into a lumen of an organ of a patient, wherein one of the position devices is configured as a transmitter and the other is configured as a receiver.

[0046] Figure 2 The illustrations in are conceptual and are given by way of example. The actual basket structure may vary. For example, the expandable spine 55 may be made of a printed circuit board (PCB) or a shape memory alloy. More generally, after making necessary changes, Figure 2 The illustrations shown in are applicable to any expandable distal tip assembly of a catheter, such as a balloon catheter, for insertion into a lumen of an organ of a patient.

[0047] Figure 3Flowchart schematically illustrates a method and algorithm for electroanatomical mapping of a cardiac chamber according to an embodiment of the present invention. According to the proposed embodiment, the algorithm executes a process that begins with a physician 30 moving a basket catheter 40 inside a cardiac chamber, the basket catheter being equipped with magnetic sensors 50A and 50B.

[0048] In one embodiment, as the catheter 40 moves within the heart chamber, the processor 41 receives signals from the sensors 50A and 50B at a signal receiving step 70. Next, at a basket proximal measurement step 72, the processor 41 estimates the position and longitudinal direction of the proximal sensor 50A based on the signals received from the proximal sensor 50A. In parallel, at a basket distal measurement step 74, the processor 41 estimates the corresponding position of the distal sensor 50B based on the signals received from the distal sensor 50B. Next, at a distal position projection step 76, the processor 41 projects any erroneous estimated position 50C of the distal sensor 50B found in step 74 onto the axis 62 defined by the estimated longitudinal direction of the proximal sensor 50A. The projected position is labeled 50D. Finally, at a basket elongation calculation step 78, the processor 41 calculates the elongation of the basket catheter 40 as the distance between the position 50A and the position 50D.

[0049] As described above, based on the calculated elongation, the diagnostic and / or treatment protocol can be improved, for example, by correcting the assumed position and orientation of the ultrasound transducer mounted on the basket catheter 40. Another example is to instruct the user to perform an action based on the calculated elongation, such as performing an elongation action of the catheter before inflating the balloon if the system recognizes that the catheter is in its retracted state.

[0050] In some embodiments, processor 41 presents the estimated elongation to physician 30, for example, using a suitable graphical or textual display on display 27. Additionally or alternatively, processor 41 may adaptively adjust the protocol or take any other suitable action based on the estimated elongation, such as preventing inflation of the balloon if the balloon catheter is determined to be in a retracted state by the disclosed techniques.

[0051] Figure 3 The exemplary flow charts shown in are chosen solely for the sake of conceptual clarity. Figure 3 The flowchart shown in is applicable to any expandable distal tip assembly of a catheter (such as a balloon catheter) for insertion into a lumen of an organ of a patient. This embodiment also includes additional steps of the algorithm, such as operating a sensor mounted on the spine of the basket, which have been intentionally omitted from the disclosure herein in order to provide a more simplified flowchart.

[0052] Although the embodiments described herein are primarily directed to cardiac applications, the methods and systems described herein may also be used in other medical applications where a catheter is inserted into a lumen of a patient's organ, such as a navigable ear, nose, and throat (ENT) probe.

[0053] It should therefore be understood that the embodiments described above are cited by way of example, and that the present invention is not limited to the contents specifically shown and described above. On the contrary, the scope of the present invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art when reading the above description, and which are not disclosed in the prior art. The documents incorporated by reference into this patent application are considered to be an integral part of this application, except that if any term defined in these incorporated documents conflicts with a definition explicitly or implicitly given in this specification, only the definition in this specification should be considered.

Claims

1. A system comprising: an expandable distal tip assembly coupled to a distal end of a shaft for insertion into a lumen of an organ of a patient; a proximal position device located at a proximal end of the distal tip assembly; a distal position device located at the distal end of the distal tip assembly, wherein one of the position devices is configured as a transmitter and the other is configured as a receiver; and A processor, the processor being configured to: estimating a distance from the receiver to the transmitter based on a signal received from the receiver; as well as The extension of the expandable distal tip assembly is indicated as the calibration distance.

2. A method comprising: transmitting a signal between a proximal position device at a proximal end of an expandable distal tip assembly coupled to a distal end of a shaft for insertion into a lumen of an organ of a patient and a distal position device at a distal end of the distal tip assembly, wherein one of the position devices is configured as a transmitter and the other is configured as a receiver; estimating a distance from the receiver to the transmitter based on the transmitted signal received from the receiver; as well as The extension of the distal tip assembly catheter is indicated as the calibration distance.

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