Shape determination of the expandable distal component of a catheter

Abstract

To provide a catheter and an associated positioning system.SOLUTION: A catheter and an associated positioning system can include sensors and software to ascertain the extent of expansion of an expandable distal member of the catheter. Sensors on the distal member can be configured such that the system is able to determine a longitudinal dimension and a radial dimension of the distal-end assembly and determine the extent of expansion of the distal member based on those metrics. At least the longitudinal dimension can be derived from advanced current localization (ACL) techniques utilizing an electrode at a distal end of the expandable distal member.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention generally relates to medical devices and their use, and more particularly, to catheters having expandable features such as balloons, spines, or other structures, related positioning systems, and treatment methods utilizing such catheters and positioning systems.

Background Art

[0002] Some intravascular procedures utilize catheters having an expandable distal member near the distal end of the catheter. For example, some catheters include a balloon or spine carrying electrodes that can be used to sense and / or ablate within a patient's vascular structure and / or heart. Some of these catheters can be used in treatments involving catheter ablation of cardiac arrhythmias. There are various catheter designs available for various purposes, and generally, the expandable distal member can be collapsed to traverse the vascular structure and is expandable within the blood vessel and / or heart. At present, during such treatments, visualization of the expandable distal member on the positioning system display and physician training are highly dependent for properly interpolating the shape, orientation, and position of the expandable distal member presented on the display.

Summary of the Invention

Means for Solving the Problems

[0003] An exemplary catheter can include a shaft, an expandable member, and a distal sensor. The catheter can further include a proximal sensor, a navigation sensor, a telescoping member, a body sensor, and / or a trifilar wire.

[0004] The shaft can extend along the longitudinal axis of the catheter and can be manipulated to position the expandable member within the patient.

[0005] The expandable member can be positioned at the distal end of the shaft. The expandable member may be movable from an expanded configuration to a collapsed configuration. The expandable member may have a longitudinal dimension parallel to the longitudinal axis that increases when the expandable member moves from an expanded configuration to a collapsed configuration. The expandable member may include a balloon and / or spine.

[0006] The distal sensor can be fixed to an expandable member. The distal sensor can provide current to an advanced current position tracking system and can be positioned to indicate the longitudinal dimensions of the expandable member.

[0007] The proximal sensor can be fixed to the catheter proximal to the distal sensor so that the distal sensor moves distally away from the proximal sensor when the expandable member moves from an expanded configuration to a collapsed configuration. The distal sensor can be positioned relative to the proximal sensor to indicate the longitudinal dimension of the expandable member when the position of the distal sensor is compared to the position of the proximal sensor. The proximal sensor can be fixed to the shaft. The proximal sensor can provide current to a state-of-the-art positioning and tracking system.

[0008] The navigation sensor can be fixed in close proximity to the proximal sensor in a static position on the catheter relative to the proximal sensor.

[0009] The telescopic member can engage with the shaft and the expandable member. The telescopic member can be configured to slide along its longitudinal axis relative to the shaft. The distal sensor can be fixed to the distal end of the telescopic member.

[0010] The main sensor is fixed to the expandable member and can be positioned to indicate the radial dimension of the expandable member. When the expandable member moves from an expanded configuration to a compressed configuration, the radial dimension perpendicular to the longitudinal axis can be reduced. The main sensor may include one or more conductive coils, each configured as a magnetic sensor. The expandable member may include an expandable membrane. Each of the one or more conductive coils may be disposed on the outer surface of the expandable membrane.

[0011] The triphiler wire may contain three traces, at least one of which is electrically connected to the distal sensor. The triphiler wire may also contain two copper traces and one constantan trace.

[0012] An exemplary catheter positioning system may include a processor and a non-transient computer-readable medium for communicating with the processor. Instructions may be executed by the processor and may include a variety of commands that cause the processor to control the operation of the system. Instructions may cause the processor to apply a first current signal between one or more conductive body surface patches and a probe electrode, the conductive body surface patches being configured for conductivity through the patient's skin, and the probe electrode being fixed to a distal expandable member of a catheter configured to be inserted into the patient's body. Instructions may cause the processor to measure a first voltage signal between at least one of the one or more conductive body surface patches and the probe electrode, the first voltage signal arising from the applied first current signal. Instructions may cause the processor to determine the length of the distal expandable member based at least in part on the first voltage signal.

[0013] The command causes the processor to determine the position of the proximal electrode, which is fixed to the catheter and positioned proximal to the probe electrode, and to determine the length of the distal expandable member, at least partially based on the position of the proximal electrode.

[0014] The instruction can cause the processor to apply a second current signal between at least one of one or more conductive body surface patches and a proximal electrode, and to measure a second voltage signal between at least one of one or more conductive body surface patches and a proximal electrode, the second voltage signal being obtained from the applied second current signal. The instruction can cause the processor to determine the length of the distal expandable member based at least in part on the second voltage signal.

[0015] The instruction can cause the processor to compare the length with a longitudinal threshold and provide an output indicating a change in the shape of the distal expandable member when the length exceeds the longitudinal threshold. The instruction can cause the processor to compare the length with a minimum recoating length, and when the length increases to exceed the minimum recoating length, it can trigger a low flow rate to the distal expandable member, preventing the initiation of a high flow rate that would cause the distal expandable member to expand. When the length decreases to below the longitudinal threshold, the instruction can allow a high flow rate that would cause the distal expandable member to expand.

[0016] The command can cause the processor to apply a magnetic field through the patient's body, measure an induced electrical signal from a navigation sensor fixed to the catheter, and determine the position of the probe electrode based on at least the induced electrical signal and a first voltage signal.

[0017] The instruction can cause the processor to determine the expansion radius of the distally expandable member. The instruction can cause the processor to compare the expansion radius with a radial threshold and provide an output indicating the change in the shape of the distally expandable member when the expansion radius exceeds the radial threshold. The radial threshold can be based at least in part on re-covering force calculations.

[0018] The instruction can cause the processor to receive one or more sensor signals from sensors fixed to the distal expandable member and radially spaced apart around the distal expandable member. The instruction can cause the processor to determine the expansion radius based on at least a portion of the one or more sensor signals.

[0019] The instruction causes the processor to compare the length to a longitudinal threshold and the expansion radius to a radial threshold, and to provide an output indicating that the catheter is sufficiently compressed to be covered when the length is greater than the longitudinal threshold and the expansion radius is less than the radial threshold. The longitudinal threshold can measure approximately 41 millimeters (mm).

[0020] An exemplary method may include one or more of the following steps, which are not presented in a particular order: A first current signal can be applied between one or more conductive body surface patches and a probe electrode, wherein the conductive body surface patches are configured for conductivity through the patient's skin, and the probe electrode is fixed to a distal expandable member of a catheter configured for insertion into the patient's body. A first voltage signal can be measured between at least one of the one or more conductive body surface patches and the probe electrode, and the first voltage signal arises from the applied first current signal. The length of the distal expandable member can be determined at least in part based on the first voltage signal.

[0021] This method may further include determining the position of a proximal electrode fixed to a catheter and positioned proximal to a probe electrode, and determining the length of a distal expandable member based at least partially on the position of the proximal electrode.

[0022] The method may further include applying a second current signal between at least one of one or more conductive body surface patches and a proximal electrode, measuring a second voltage signal between at least one of one or more conductive body surface patches and a proximal electrode, wherein the second voltage signal arises from the applied second current signal, and determining the length of a distally expandable member based at least in part on the second voltage signal.

[0023] The method can further include comparing the length with a longitudinal threshold value and providing an output indicating a change in the shape of the distally expandable member when the length exceeds the longitudinal threshold value.

[0024] The method can further include applying a magnetic field to a patient's body, measuring an induced electrical signal from a navigation sensor fixed to the catheter, and determining the position of the probe electrode based at least on the induced electrical signal and a first voltage signal.

[0025] The method can further include determining an expansion radius of the distally expandable member. The method can further include comparing the expansion radius with a radial threshold value and providing an output indicating a change in the shape of the distally expandable member when the expansion radius exceeds the radial threshold value. The method can further include receiving one or more sensor signals from sensors fixed to the distally expandable member and radially spaced around the distally expandable member and determining the expansion radius based at least in part on the one or more sensor signals.

[0026] The method can further include comparing the length with a longitudinal threshold value, comparing the expansion radius with a radial threshold value, and providing an output indicating that the catheter is sufficiently collapsed to be covered when the length is greater than the longitudinal threshold value and the expansion radius is less than the radial threshold value. The longitudinal threshold value can be measured to be about 41 mm. The method can further include that the radial threshold value is at least partially based on the recoating force calculation.

Brief Description of the Drawings

[0027] [Figure 1A] FIG. is a view of the distal portion of an exemplary catheter and sheath in a partially collapsed, cutaway view, according to an aspect of the present invention. [Figure 1B] FIG. is a view of the distal portion of an exemplary catheter in an expanded state, with exemplary surface details illustrated, according to an aspect of the present invention. [Figure 2]A diagram of an exemplary positioning system according to an aspect of the present invention. [Figure 3] A flowchart outlining method steps according to an aspect of the present invention. [Figure 4] A diagram of another exemplary distal portion of a catheter according to an aspect of the present invention. **DETAILED DESCRIPTION OF THE INVENTION**

[0028] The following description of specific embodiments of the present invention should not be used for the purpose of limiting the scope of the present invention. The drawings are not necessarily to scale and show selected embodiments and are not intended to limit the scope of the present invention. The detailed description is illustrative by way of example and does not limit the principles of the present invention. Other examples, features, aspects, embodiments, and advantages of the present invention will be apparent to those skilled in the art from the following description, which includes as an example one of the best modes contemplated for carrying out the present invention. As will be understood, the present invention is capable of other different aspects or equivalent aspects without departing from the present invention. Therefore, the drawings and description should be regarded as being of an illustrative nature and not of a limiting nature.

[0029] The teachings, formulas, variations, examples, etc. described herein may be combined with other teachings, formulas, variations, examples, etc. described herein, including those provided in the references attached to the priority U.S. application No. 63 / 092,168. Therefore, the teachings, expressions, variations, examples, etc. described below should not be considered independently of each other. Various suitable ways of combining the teachings of this specification will be apparent to those skilled in the art in light of the teachings of this specification. Such modifications and variations are intended to be included within the scope of the "claims".

[0030] As used herein, the terms “about” or “approximately” for any number or range of numbers indicate a suitable dimensional tolerance that enables some or a set of components to function in accordance with the intended purpose set forth herein. More specifically, “about” or “approximately” may refer to a range of values ​​within ±20% of the listed values; for example, “about 90%” may refer to a range of values ​​between 71% and 99%.

[0031] As used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject, and are not intended to limit the use of the systems or methods described above to human use, however, the use of the present invention in human patients is representative of preferred embodiments.

[0032] As used herein, the term “non-transient computer-readable medium” includes, but is not limited to, random-access memory (RAM), read-only memory (ROM), electronically erasable programmable ROM (EEPROM), flash memory or other memory technologies, compact disk ROM (CD-ROM), digital purpose disc (DVD) or other optical storage devices, magnetic cassettes, magnetic tapes, magnetic disk storage devices or other magnetic storage devices, or any other tangible physical medium that can be used to store computer-readable information.

[0033] As used herein, the term “wire” may include elongated solid core and hollow core structures. When used to refer to a conductor, the term “wire” may include insulated conductors, non-insulated conductors, individual conductors, bundled conductors, and integrated circuit conductors.

[0034] The expandable distal members of catheters, such as balloon catheters or basket catheters, which are inserted into a patient's blood vessels or organ cavities, can be used for a variety of clinical applications, such as electroanatomical mapping and ablation of intracardiac or pericardial vascular structures or cardiac cavity walls. Generally, expandable distal members collapse when delivered through a body cavity (e.g., a vascular structure) to the treatment site, expand upon arrival at the treatment site, and collapse again for extraction or repositioning. A distal member that is not sufficiently expanded may not be effective in delivering treatment, and movement of a distal member that is not sufficiently collapsed may result in trauma to the patient or damage to the distal member.

[0035] It may be advantageous to map the position and / or shape of the expandable distal end assembly of a catheter. U.S. Patents 7,756,576, 7,848,787, 7,869,865, and 8,456,182, respectively, are incorporated herein by reference and are attached to U.S. Priority Application No. 63 / 092,168, which describe mapping tools utilizing multiple tracking techniques, including advanced current localization (ACL), electromagnetic (EM) systems, fluoroscopy systems, magnetic resonance imaging (MRI) systems, and ultrasound systems. U.S. Patent Publication 2020 / 0206461, incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168, describes a system for determining the extension of the distal end of a catheter. Incorporated herein by reference, U.S. Patent Publication 2020 / 0155224, attached to the Annexes of U.S. Priority Application No. 63 / 092,168, describes configuring the outer circumference of a balloon electrode as a position sensor.

[0036] In the case of balloon catheters, the balloon is inflated and deflated by pressurizing a fluid (e.g., saline solution) through the inflation tube and / or the lumen of the catheter. Some balloon catheters include mechanisms to facilitate the inflation and deflation of the balloon. See, for example, U.S. Patent Publications 2018 / 0140807, 2018 / 0161093, 2019 / 0059818, 2019 / 0201669, 2019 / 0217065, 2020 / 0147295, and U.S. Patent No. 9,907,610, respectively, which are incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168 in the appendices. Further exemplary irrigation balloons including electrodes for sensing and / or ablation are described in U.S. Patent Publication No. 2020 / 0155226, U.S. Patent Publication No. 2019 / 0298441, and U.S. Patent No. 7,410,486, respectively, which are incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168.

[0037] In the case of an end-effector or other spine structure, the spine may self-expand upon exiting the sheath or delivery catheter and collapse upon re-covering. In addition, or alternatively, it may be mechanically expanded via the operation of a tension wire or tension tube (collectively referred herein as “tension wire”). See, by reference, U.S. Patent Publication 2020 / 0155224, incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168.

[0038] The exemplary catheters and associated control systems presented herein may include sensors and software for determining the degree of distal member dilation, and the potential benefit of such exemplary catheters and systems is that they can reduce the likelihood of undesirable treatment outcomes arising from inadequately dilated and / or inadequately compressed distal members. In some embodiments, sensors on the distal member may be configured so that the system can determine the longitudinal and radial dimensions of the distal member and, based on those measurements, determine the degree of distal member dilation. In some embodiments, one or both of these measurements can be obtained from ACL technology. Preferably, the catheter includes a distal electrode that functions as an ACL sensor providing a signal that can be used to derive the length of the distal member. The drawings described herein include several diagrams showing how such catheters and control systems may be configured. The appendices attached to U.S. Priority Application No. 63 / 092,168, which can be combined in accordance with the teachings herein, include a description of relevant technology that can be used to measure and / or utilize longitudinal and / or radial dimension measurements, by modifying or substituting the exemplary embodiments herein.

[0039] Figures 1A and 1B show an exemplary balloon catheter 100. The catheter 100 includes an expandable distal member 110 connected to the distal end of a shaft 102. The shaft 102 defines the longitudinal axis 10 of the catheter 100. The proximal 12 and distal 14 directions are shown. The catheter 100 is shown in a partially flattened state in preparation for recoating in Figure 1A and in an expanded configuration in Figure 1B. Figure 1A is a cutaway view showing electrodes 104, 108 that may be used to determine the longitudinal dimension 18 of the expandable distal member 110 of the catheter 100. Figure 1B is an external view of the expandable distal member 110 showing a guide coil 122 that may be used to determine the position and / or radial dimension 24 of the distal member 110. When the longitudinal dimension 18 and / or radial dimension 24 are within a specific range, the expandable distal member 110 can be re-covered with an acceptablely low risk of patient trauma and / or catheter 100 damage. The longitudinal dimension 18 and / or radial dimension 24 can also be used to provide user feedback regarding the shape and / or position of the distal expandable member 110 for purposes other than re-covering. The longitudinal dimension 18 and / or radial dimension 24 can also be used to provide control feedback to the control system (see Figure 2).

[0040] The catheter 100 includes both an electrical position tracking subsystem and a magnetic position tracking subsystem. The electrical position tracking subsystem is referred to herein as the ACL system, and the magnetic position tracking subsystem is referred herein as the EM system. Preferably, the electrical position tracking subsystem includes a distal electrode 108 and a proximal electrode 104. The magnetic position tracking subsystem preferably includes a navigation sensor 136 fixed to the shaft 102 of the catheter 100 in close proximity to the proximal sensor 104. As illustrated, when the electrical position tracking subsystem includes the proximal electrode 104 and the magnetic tracking system includes the navigation sensor 136, the proximal electrode 104 and the navigation sensor 136 are fixed at a known distance from each other and thus provide a common reference point between the two subsystems that can be used to improve the accuracy of position, shape, and / or orientation calculations based on the two subsystems. The magnetic position tracking subsystem may include a guide coil 122 on the balloon membrane 116. The electrical tracking subsystem may include an ablation electrode 114 on the balloon membrane 116.

[0041] The proximal electrode 104, distal electrode 108, and guide coil 122 can each be reconfigured to function with either an electrical or magnetic position tracking subsystem, as will be understood by those skilled in the art according to the teachings herein. The catheter 100 may include additional sensors and electrodes, not shown, that can be used to determine the position, orientation, and / or shape of the expandable distal member 110, as will be understood by those skilled in the art according to the teachings herein. The catheter 100 can be further adapted according to a hybrid tracking system approach, as described in U.S. Patents 7,756,576, 7,848,787, 7,869,865, and 8,456,182, respectively, which are incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168.

[0042] The distal electrode 108 can be modified to function as a guide sensor, but instead, configuring the distal electrode 108 to function within the electrical position tracking subsystem does not require a complex wiring and electrode shape, especially when the proximal electrode 104 is configured within the electrical tracking subsystem. Furthermore, a catheter including a distal radiopaque marker at the position of the distal electrode 108, as shown in the figure, can be modified by providing a conductor to the distal marker without requiring a significant change in the shape or configuration of the distal marker.

[0043] The proximal electrode 104 and distal electrode 108 are connected to a conductor (e.g., a wire or conductive trace) extending through the shaft 102 of the catheter 100. In some embodiments, the conductor to the distal electrode 108 may be a separate wire. The wire may extend along the ablation electrode 114 to the distal electrode 108 together with a bundled wire in the shaft 102. Alternatively, a trifiller wire may extend to the ablation electrode 114 and the distal electrode 108, with one of the conductors of the trifiller wire being a copper conductor terminating at the distal electrode 108. The conductor may be connected to a control unit 220 in a positioning system 200, as shown in Figure 2. The system 200 can determine the longitudinal dimension 18 by measuring the distance between the proximal electrode 104 and the distal electrode 108 using ACL. The functions of the system 200 will be described in more detail with reference to Figure 2.

[0044] Referring to Figure 1A, the catheter 100 may include an expandable shaft 106 that provides structural support to the balloon membrane 116 and can be operated to expand or retract the balloon. The distal electrode 108 may be fixed to the distal end of the expandable shaft 106 in relation to the distal expandable shaft 106. The expandable shaft 106 can slide in and out of the catheter shaft 102 to shorten and extend the longitudinal dimension 18 of the expandable distal member 110. Additionally or alternatively, as described in U.S. Patent Publication Nos. 2018 / 0140807, 2018 / 0161093, 2019 / 0059818, 2019 / 0201669, 2019 / 0217065, 2020 / 0147295, and U.S. Patent No. 9,907,610, which are incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168, the expandable distal member 110 may include alternative structural components that simplify the controlled extension and shortening of the longitudinal dimension 18 of the expandable distal member 110. In catheters lacking an extendable shaft 106, the distal electrode 108 can be fixed to the distal end of the balloon, thereby allowing the distal electrode 108 to move longitudinally relative to the catheter shaft 102 when the balloon expands and collapses.

[0045] The catheter 100 can be retracted into the sheath 130. As shown in the figure, the sheath 130 may include a sheath position sensor 132 positioned on the distal end of the sheath 130. The sheath position sensor 132 may be connected by a conductor to a control unit 220 of the system 200 shown in Figure 2. The sheath position sensor 132 can be used to determine the position of the expandable distal member 110 relative to the distal end of the sheath 130. For example, the system 200 may be configured to determine the distance 16 between the proximal electrode 104 on the shaft 102 of the catheter 100 and the sheath position sensor 132. As described in U.S. Patent Application No. 16 / 657,463, filed on 18 October 2019 and published on 22 April 2021 as U.S. Patent Publication No. 2021 / 0113822, attorney reference number BIO6167USNP1, incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168, the catheter 100 and system 200 can be configured to detect the event in which the expandable distal member 110 is at least partially expanded but retracted into the sheath.

[0046] Referring to Figure 1B, the ablation electrodes 114 are evenly distributed on the equidistant circle 118 of the expandable membrane 116 of the expandable distal member 110. Each coil 122 is wound around the outer circumference of each RF ablation electrode 114. The coils 122 can be placed on a flexible printed circuit board (PCB) 126, and the flexible PCB 126 can be attached to the expandable membrane 116. Each ablation electrode 114 and each coil 122 can share lead wires 112. As shown in inset 120, each coil 122 consists of several turns 124 (i.e., windings 52). Each turn 124 of the coil 122 has a width of several tens of micrometers, so the total width 128 of the outer circumference (i.e., of the coil 122) is kept to several hundred micrometers or less. Each ablation electrode 114 can have an area of ​​several tens of millimeters (mm), and as a result, the coil 122 wound several times around the periphery of the electrode has an effective area of ​​several hundred square millimeters. The typical width of the turns on the coil 122 is about 40 to about 50 micrometers, and therefore 6 or 7 turns result in an effective area of ​​about 250 to about 350 square mm. The coil 122 is connected to a control unit 220 (Figure 2) which can determine the radial dimension 24 of the expandable distal member 110. In some embodiments, the coil 122 can be used to determine the position of the expandable distal member 110, in which case the coil 122 can be used in place of or as an auxiliary to the navigation sensor 136. This function can be realized using a catheter and system as described in U.S. Patent Publication No. 2020 / 0155224, which is incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168.

[0047] The examples shown in Figures 1A and 1B are selected solely for the purpose of clarifying the concept. Other shapes of the balloon, ablation electrode, and coil 122 are also possible. The expandable distal member 110 may include further mechanisms not shown, such as an irrigation port and a temperature sensor, which are omitted for clarity.

[0048] Figure 2 shows an exemplary system 200 that can be used to manipulate and drive the catheter 100 in clinical applications. In an exemplary procedure, a physician 20 can navigate the catheter 100 through a vascular structure to position the expandable distal member 110 within or near the heart 26 of a patient 22 (see inset 202). Additionally or alternatively, the positioning system 200 can be used in other body cavities with a probe similar to the catheter 100.

[0049] System 200 may include both an electrical position tracking subsystem and a magnetic position tracking subsystem. As shown in the figure, the electrical position tracking subsystem includes a body surface electrode (ACL patch) 218 ​​configured to interact with the electrical position tracking subsystem of the catheter 100 (e.g., electrodes 104, 108), thereby enabling the measurement of impedance measurements between the ACL patch 218 and the catheter electrical position tracking electrodes 104, 108. The magnetic position tracking subsystem preferably includes a positioning pad 204, which includes a coil 206 configured to generate and / or receive a magnetic field within the patient 22 that interacts with the magnetic position tracking subsystem of the catheter 100 (e.g., navigation sensor 136 and / or coil 122). The magnetic position tracking subsystem may further include a reference patch 210 positioned within the patient's body as another mode for determining catheter position, which is attached to the patient's skin (as shown in the figure). System 200 may further include an ablation patch 208 placed on the patient 22, which can provide a return path for the ablation electrode 114 of the catheter 100. As described in U.S. Patents No. 7,756,576, No. 7,848,787, No. 7,869,865, and No. 8,456,182, respectively, which are incorporated herein by reference and attached to U.S. Priority Application No. 63 / 092,168, System 200 can be further adapted according to a hybrid tracking system approach. Various configurations of the electrical position tracking subsystem, magnetic position tracking subsystem, and other tracking systems are described elsewhere and are briefly mentioned here for the sake of brevity. System 200 may include additional components that will be understood by those skilled in the art, which are omitted for clarity.

[0050] The illustrated system 200 includes a control unit 220 for driving the system 200 and providing a user interface. The control unit 220 includes a processor 232 and a memory 230. The processor 232 communicates with components and modules of the control unit 220, including a console 222, an ablator module 228, a pump 238, an electrical tracking system driver 234, and a magnetic tracking system driver 236. The processor 232 may also communicate with components or modules not shown for simplification. The memory 230 can store instructions that can be executed by the processor 232, which in turn allow the control unit 220 and the system 200 to perform various functions described herein. The memory may further include instructions for performing additional functions not described herein for brevity, including functions that will be understood by those skilled in the art. The memory 230 and the processor 232 are exemplified as a single functional block, but can actually be distributed. Similarly, console 222 is shown as having the ablator module 228, pump 238, electrical tracking system driver 234, and magnetic tracking system driver 236 integrated into an integrated control unit 220. However, each of these components may be individual or combined in various configurations, as will be understood by those skilled in the art.

[0051] The console 222 can function as a user interface to the physician 20 and may include a visual display 224 and user inputs 226 (e.g., buttons, knobs, touchscreens, etc.). The ablator module 228 can supply energy to the ablation electrode 114 of the catheter 100 and / or receive electrical signals from the electrode 114 for diagnostic purposes. The pump 238 can provide fluid pressure to inflate and deflate the balloon membrane 116 of the catheter 100 and can be omitted when an alternative catheter without a balloon (see, for example, catheter 400 in Figure 4) is used instead of the illustrated catheter 100. The electrical tracking system driver 234 provides energy output and sensor input for the electrical position tracking subsystem. The magnetic tracking system driver 236 provides energy output and sensor input for the magnetic position tracking subsystem.

[0052] The proximal electrode 104 and distal electrode 108 can function as independent blood-contact electrodes providing ACL mapping position functionality to an implanted magnetic position sensor of the catheter 100, which may be a coil 122 on the balloon membrane 116 and / or a navigation sensor 136 on the shaft 102. The distal electrode 108 can be used to visualize the shape, position, and / or orientation of the expandable distal member 110 of the catheter. In particular, the distal electrode 108 can determine the length 18 between the distal electrode 108 and the proximal electrode 104, thereby determining the longitudinal dimension of the expandable member 110. The angular position of the ablation electrode 114 can also be used to visualize the shape, position, and / or orientation of the expandable distal member 110. The angular position of the ablation electrode 114 can be visualized using the guidance signal of the coil 122. Additionally or alternatively, the angular position of the ablation electrode 114 can be visualized by using the ablation electrode 114 as an electrode driven by an electrical tracking system driver 234, using techniques similar to those applied to the distal electrode 108 and proximal electrode 104. The angular position of the ablation electrode 114 can be used to determine the radial dimension 24 of the expandable distal member 110.

[0053] The control unit 220 can display the shape and / or position of the catheter 100 on a visual display. The display 224 can also provide an indication of whether the expandable distal member 110 is sufficiently compressed for re-covering. A color-coded visualization can be displayed on the visual display 224 (e.g., red when the expandable distal member 110 is not sufficiently compressed, and green when the member 110 is sufficiently compressed for re-covering). Displayed warnings or conditions may be shown on the visual display 224 (e.g., "Re-covering prohibited" / "Re-covering OK"). System-level signals based on the shape of the expandable distal member 110 may be sent to the pump 238 to reduce or reverse the flow from the catheter 100 to the balloon membrane 116 in order to facilitate the deflation of the expandable distal member 110. When the expandable distal member 110 is expanded, high flow from the pump 238 can be avoided, and high flow can be turned off when the expandable distal member 110 is actuated to the expanded position. Furthermore, a "contraction index" can be generated based on the length of the expandable distal member 110 and the relative level of fluid within the membrane 116, which is determined based on the radial dimension 24. The "contraction index" can be used based on characterization and verification to indicate that it is safe to re-cover or reposition the expandable distal member 110. Such feedback to the physician 20 and / or control unit 220 can reduce the risk of improper handling that could damage the catheter 100 and / or harm the patient 22 by reducing reliance on the physician's explanations regarding system outputs such as fluoroscopic visualization of the ablation electrode 114 or radiopaque markers in place of the distal electrode 108. In some treatments, it may be difficult for the physician to accurately interpolate the overall balloon length based solely on fluoroscopic visualization of the orientation of the expandable distal member 110.

[0054] The processor 232 drives the electrical tracking system driver 234 so that it can determine the length between the proximal electrode 104 and the distal electrode 108, and can send and receive appropriate electrical signals between the body surface patch 218, the proximal electrode 104, and the distal electrode 108. For example, a first electrical signal can be applied between the body surface patch 218 and the distal electrode, and a first voltage signal resulting from the first electrical signal can be measured; a second electrical signal can be applied between the body surface patch 218 and the proximal electrode, and a second voltage signal resulting from the second electrical signal can be measured; and the longitudinal dimension of the distal expandable member 110 can be determined at least in part based on the first and second voltage signals.

[0055] The processor can compare the length 18 between the proximal electrode 104 and the distal electrode 108 (corresponding to the longitudinal dimension of the distal expandable member 110) with a longitudinal threshold. When the length or longitudinal dimension exceeds the threshold, the processor can provide an output indicating a change in the shape of the distal expandable member 110. The output can be used to provide a user display (e.g., on a display 224) and / or to output electrical signals to control the system 200.

[0056] The processor 232 can drive the magnetic tracking system driver 236 to generate a magnetic field through the patient's body and measure induced electrical signals from navigation sensors (e.g., coil 122 and / or navigation sensor 136) fixed to the catheter 100. The position of the distal electrode 108 can be determined at least in part on the voltage signal received as a result of the electrical tracking system driver 234 applying current between the distal electrode 108 and the body surface electrode 218, and at least in part on the measured induced electrical signals from the navigation sensors.

[0057] The processor 232 can determine the expansion radius of the distal expandable member 110, which is related to the radial dimension 24 shown in Figure 1A. The processor can compare the expansion radius with a radial threshold. When the expansion radius exceeds the radial threshold, the processor 232 can provide an output indicating a change in the shape of the distal expandable member 110.

[0058] The processor 232 is fixed to the distal expandable member 110 and can receive one or more sensor signals from sensors (e.g., coil 122) radially spaced around the distal expandable member 110. Based at least partially on one or more sensor signals, the processor 232 can determine the expansion radius of the distal expandable member 110.

[0059] The processor compares the length 18 between the proximal sensor 104 and the distal sensor with a longitudinal threshold, and compares the expansion radius with a radial threshold. When the length is greater than the longitudinal threshold and the expansion radius is less than the radial threshold, it can provide an output indicating that the catheter is sufficiently compressed to cover the surface.

[0060] The threshold can be reached as follows: With an expandable distal member 110 having a length 18 of approximately 45 mm, subtract the distance (approximately 2 mm) from the distal end 134 of the distal electrode 108 to the proximal edge 138 of the distal electrode 108, thereby reducing the potential error in ACL measurement (variable ±1 mm or 2 mm). This yields an estimated threshold of a minimum of 41 mm. With a sheath 130 and balloon membrane 116 of typical size, the catheter 100 can be re-covered with the minimum acceptable risk of damage when the length 18 measures approximately 38.5 mm, well below the 41 mm threshold, even considering potential measurement errors, and the system 200 can be configured to provide a reliable indication that the expandable distal member 110 is sufficiently expanded for re-covering when the measured length 18 is above the 41 mm threshold. For illustrative purposes, in this embodiment, the length 18 at which the catheter 100 can be re-covered with the minimum acceptable risk of damage is referred to herein as the “minimum re-covering length”. In this embodiment, the longitudinal threshold can be measured to be approximately 41 mm. The longitudinal threshold can be similarly calculated for other catheter shapes. Based on this embodiment, the system 200 can provide user feedback or system feedback based on length 18 for the following three possible scenarios: (1) the "balloon expansion" state when length 18 exceeds 41 mm; (2) the "transition to expansion" state when the balloon is expanding and length 18 exceeds 38.5 mm but is below the 41 mm threshold; and (3) the "balloon retraction" state when the balloon is retracting and exceeds the 41 mm threshold. The numerical value of length 18 in the exemplary scenarios may depend on the shape of the specific catheter and sheath.

[0061] The radial threshold may be at least partially based on the re-covering force calculation and, like the longitudinal threshold, may be specific to the shapes of the catheter 100 and sheath 130. Comparison of the radial dimension 24 with the radial threshold can provide an alternative or supplementary means for determining the deflation of the balloon membrane 116. Other techniques that can be used to determine deflation include plotting the flow rate, balloon length, and latency against the peak re-covering force. Similarly, the radial dimension 24 can be plotted against the peak re-covering force to determine the radial threshold. The system 200 may further provide user feedback or system feedback based on the radial dimension 24 for two possible scenarios: (1) a "balloon pressurized" state when the radial dimension 24 is greater than the radial threshold, and (2) a "balloon depressurized" state when the radial dimension 24 is less than the radial threshold.

[0062] When both the "balloon expanded" and "balloon deflated" states are active, catheter 100 can be considered sufficiently deflated to be re-covered. The "balloon expanded" and "expansion transition" states can trigger a low flow rate and prevent the pump 238 from operating a high flow rate. The "balloon retracted" state can enable a high flow rate at pump 238. The "balloon pressurized" state generates a system pressure indicator that can be used in conjunction with the deflation index. The "balloon deflated" state can also generate a system pressure indicator.

[0063] Table 1 shows an exemplary balloon contraction index logic matrix depending on the “balloon expansion,” “expansion transition,” “balloon retraction,” “balloon pressurization,” and “balloon decompression” states described above. In Table 1, length 18 is abbreviated as “LD,” radial dimension 24 as “RD,” and radial threshold is represented by the variable “Y.” In Table 1, following the example above, the longitudinal threshold is set to 41 mm and the minimum re-covering length is set to 38.5 mm. These values ​​may vary depending on the shape details of the expandable member 110 and sheath 130. Table 1 includes exemplary system outputs corresponding to each state in columns and rows. In addition, the system provides annotations when both the “balloon expansion” and “balloon decompression” states are active. * As shown by, the system can provide an indication that the distal expandable member 110 is sufficiently compressed to be recovered. For all other combinations of states, the system can provide an indication that the distal expandable member 110 is sufficiently compressed to be recovered, as shown by note†.

[0064] [Table 1]

[0065] Figure 3 is a flowchart of a method 300 that may be used during treatment to determine whether the distal expandable portion of a catheter is sufficiently deformed to be re-covered with an acceptable risk of damage to the distal expandable portion. The method steps may also be modified to determine the shape of the distal expandable portion for other purposes, such as sufficient expansion to juxtapose treatment areas or sufficient deformation to move from one treatment area to another outside the sheath. The method can be carried out using the system 200 shown in Figure 2 and the catheter 100 shown in Figures 1A and 1B, its deformation, and alternatives as will be understood by those skilled in the art following the teachings herein. For example, a catheter 400 that can be used instead of the catheter 100 shown in Figures 1A and 1B is shown in Figure 4.

[0066] In step 302, the longitudinal dimension of the distal expandable member is estimated at least in part based on the ACL measurement of the distal electrode on the distal end of the distal expandable member. The longitudinal dimension is relative to the longitudinal axis of the catheter, such as the axis 10 of the catheter 100 shown in Figure 1A. The distal expandable member can be configured as the distal expandable member 110 illustrated in Figures 1A and 1B, the distal expandable member 410 illustrated in Figure 4, a substitute thereof, or a variation as understood by those skilled in the art. The distal electrode can be configured similarly to the distal electrode 108 shown in Figures 1A and 1B, the distal electrode 408 illustrated in Figure 4, a substitute thereof, or a variation as understood by those skilled in the art.

[0067] ACL measurement may include applying a first current signal between one or more conductive body surface patches and a distal electrode, and measuring a first voltage signal between one or more conductive body surface patches and a distal electrode, wherein the first voltage signal is obtained from the applied first current signal. The impedance between the distal electrode and the body surface patch can be calculated based on the first current signal and the first voltage signal. The longitudinal dimension (i.e., length) of the distal expandable member can be determined at least in part based on the first voltage signal (e.g., based on the calculated impedance). The conductive body surface patches may be configured for conductivity through the patient's skin, similar to the ACL patch 218 shown in Figure 2, or otherwise as understood by those skilled in the art.

[0068] The longitudinal dimension can also be estimated in part on the position of the proximal electrode, which is fixed to the catheter and positioned proximal to the distal electrode. The proximal electrode can be configured as the proximal electrode 104 shown in Figures 1A and 1B, the proximal electrode 404 illustrated in Figure 4, its substitutes, or variations as understood by those skilled in the art. The position of the proximal electrode can be determined in relation to the distal electrode and / or with respect to another criterion fixed to or related to the patient. A second current signal can be applied between at least one of one or more conductive body surface patches and the proximal electrode. A second voltage signal can be measured between at least one of one or more conductive body surface patches and the proximal electrode, and the second voltage signal arises from the applied second current signal. The longitudinal dimension can be determined at least in part on the second voltage signal (for example, based on the calculated impedance between the proximal electrode and the body surface patch).

[0069] In step 304, the radial dimension of the distal expandable member can be estimated. The radial dimension is perpendicular to the longitudinal axis of the catheter, such as the radial dimension 24 shown in Figure 1A. Therefore, the radial dimension is proportional to the expansion radius of the expandable distal member. The radial dimension can be determined by a variety of methods, including those described elsewhere in this specification, their substitutes, and variations that will be understood by those skilled in the art. For example, one or more sensor signals can be received from sensors fixed to the distal expandable member and radially spaced around the distal expandable member, and the expansion radius can be determined based on at least a portion of the one or more sensor signals.

[0070] In step 306, a user indication can be provided as to whether the distal expandable member is sufficiently compressed to be re-covered, at least partially based on the longitudinal dimension and the radial dimension estimated in steps 302 and 304. To determine whether the distal expandable member is sufficiently compressed, the expansion radius can be compared to a radial threshold, and the longitudinal dimension can be compared to a longitudinal threshold. If the expansion radius is less than the radial threshold and the longitudinal dimension is greater than the longitudinal threshold, the distal expandable member can be considered sufficiently compressed. If the catheter 100 shown in Figures 1A and 1B has dimensions suitable for use in the treatment shown in Figure 2, the longitudinal threshold can be measured to be approximately 41 mm. The radial threshold can be at least partially based on a re-covering force calculation (i.e., the amount of tensile force required to pull the expandable distal member into the sheath as a function of the radial dimension of the expandable distal member).

[0071] Although not specifically shown in the flowchart, several other useful user indicators or system feedback controls can be implemented based on the estimated longitudinal and / or radial dimensions. For example, when the expansion radius exceeds a radial threshold, an output indicating a change in the shape of the distal expandable member can be provided. When the longitudinal dimension exceeds a longitudinal threshold, a change in the shape of the distal expandable member can be indicated.

[0072] The position and orientation of the distal expandable member relative to the patient's anatomical structure can also be visualized. In some embodiments, this visualization can be achieved using a magnetic navigation system. A magnetic field can be applied through the patient's body and induced electrical signals from a navigation sensor fixed to the catheter. In some embodiments, the position of the distal electrode can be determined based on at least the induced electrical signal and a first voltage signal (from ACL technology).

[0073] Figure 4 shows an alternative catheter 400 that can be used in place of catheter 100 in the system 200 shown in Figure 2. Catheter 400 includes a shaft 402, a navigation sensor 436, a proximal electrode 404, and a distal electrode 408, configured similarly to the corresponding structures 102, 136, 104, and 108 of catheter 100 shown in Figures 1A and 1B. Instead of the balloon membrane 116 of catheter 100 shown in Figures 1A and 1B, catheter 400 shown in Figure 4 includes a spine 434 on a distal expandable member 410. The spine 434 carries an electrode 414 that can be driven to ablate and / or used to sense intracardiac electrical signals. Electrode 414 can be complemented or replaced by other sensors, such as an ultrasonic transducer. The spine 434 can self-expand and can be crushed by the force exerted on the spine 434 from the sheath 130 when the expandable distal member 410 is retracted into the sheath 130 in the proximal direction 12.

[0074] The deployment of the expandable distal member 410 is typically achieved manually. Using techniques that do not measure the longitudinal dimension 18 and radial dimension 24, there is little (e.g., indirect) indication of whether the expandable distal member 410 is fully expanded within the cavity, making it difficult to obtain accurate measurements of the expandable distal member's shape, such as ellipses within the cavity. For example, if the basket ellipticity is not known, measurements relying on a known ellipticity may yield distorted results. For instance, signals from ultrasonic transducers mounted on multiple expandable spines 434 of the basket 410 may be miscalibrated due to incorrect assumptions about the basket ellipticity, leading to errors in the assumed relative position and orientation of the ultrasonic transducers, potentially causing the processor to generate a distorted anatomical map of the cavity.

[0075] To address this problem, the proximal electrode 404 and distal electrode 408 are used in the same manner as described with respect to the proximal electrode 104 and distal electrode 108 of catheter 100 shown in Figures 1A and 1B to determine the longitudinal dimension 18 of catheter 400. Preferably, the distal electrode 408 is configured to function with an ACL (electrical) positioning system. More preferably, both the distal electrode 408 and the proximal electrode are configured to function with an electrical position tracking subsystem, and the navigation sensor is configured to function with a magnetic position tracking subsystem. The basket ellipticity can be estimated based on the longitudinal dimension 18. When used with system 200, system 200 may be configured to provide user indication and system feedback based on a longitudinal threshold similar to that described elsewhere in this specification.

[0076] The catheter 400 may optionally be equipped with a sensor to determine the radial dimension 24. For example, the electrode 414 may be configured to function with an electrical positioning subsystem and / or an induction coil, and / or the induction coil may be added to the spine 434 and configured to function with a magnetic position tracking subsystem. The radial dimension 24 may be determined in the same manner as described elsewhere in this specification. The radial threshold may provide user and / or system feedback in the same manner as described elsewhere in this specification.

[0077] While features and elements are described above in specific combinations, those skilled in the art will understand that each feature or element can be used individually or in combination with other features and elements. In addition, the methods described herein may be implemented in computer programs, software, or firmware incorporated into computer-readable media for execution on a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM discs and digital multi-purpose discs (DVDs).

[0078] [Implementation Method] (1) A catheter, A shaft extending along the longitudinal axis of the catheter, An expandable member positioned close to the distal end of the shaft and movable from an expanded configuration to a collapsed configuration, the expandable member having a longitudinal dimension parallel to the longitudinal axis that increases when the expandable member moves from the expanded configuration to the collapsed configuration, A distal sensor is fixed to the distal portion of the expandable member and configured to supply current to the advanced current position tracking system, A catheter equipped with [a specific feature / equipment]. (2) The system further comprises a proximal sensor fixed to the shaft in a proximal direction relative to the distal sensor, wherein when the expandable member moves from the expanded configuration to the collapsed configuration, the distal sensor moves distally away from the proximal sensor. The catheter according to Embodiment 1, wherein the distal sensor is positioned relative to the proximal sensor and indicates the longitudinal dimension of the expandable member. (3) The catheter according to Embodiment 2, further comprising a navigation sensor fixed in close proximity to the proximal sensor at a static position on the catheter with respect to the proximal sensor. (4) The catheter according to Embodiment 1, further comprising an expandable member configured to engage with the shaft and the expandable member and to slide relative to the shaft along the longitudinal axis, wherein the distal sensor is fixed in close proximity to the distal end of the expandable member. (5) The catheter according to Embodiment 1, further comprising a main body sensor fixed to the expandable member and positioned to indicate the radial dimension of the expandable member, wherein the radial dimension is perpendicular to the longitudinal axis and decreases when the expandable member moves from the expanded configuration to the collapsed configuration.

[0079] (6) The main unit sensor comprises one or more conductive coils, each of which is configured as a magnetic sensor. The expandable member comprises an expandable membrane, The catheter according to embodiment 5, wherein each of the one or more conductive coils is disposed on the outer surface of the expandable membrane. (7) The catheter according to Embodiment 1, wherein the expandable member comprises a balloon. (8) The catheter according to Embodiment 1, wherein the expandable member comprises one or more spines. (9) The catheter according to Embodiment 1, further comprising a trifilar wire having three traces, including two copper traces and one constantan trace, wherein one of the three traces is electrically connected to the distal sensor. (10) A catheter positioning system, Processor and A non-temporary computer-readable medium that communicates with the processor, and when executed by the processor, the processor The method involves applying a first current signal between one or more conductive body surface patches and a probe electrode, wherein the conductive body surface patches are configured for conductivity through the patient's skin, and the probe electrode is fixed to a distal expandable member of a catheter configured for insertion into the patient's body. Measuring a first voltage signal between at least one of the one or more conductive body surface patches and the probe electrode, wherein the first voltage signal arises from the applied first current signal. The length of the distal expandable member is determined based at least partially on the first voltage signal, A non-temporary computer-readable medium having an instruction to perform the following: A catheter positioning system equipped with the following features.

[0080] (11) When the non-temporary computer-readable medium is executed by the processor, the processor: The position of the proximal electrode, which is fixed to the catheter and positioned proximal to the probe electrode, is determined. The length of the distal expandable member is determined based at least partially on the position of the proximal electrode, The catheter positioning system according to embodiment 10, further comprising commands to perform the following. (12) When the non-temporary computer-readable medium is executed by the processor, the processor: Applying a second current signal between at least one of the one or more conductive body surface patches and the proximal electrode, Measuring a second voltage signal between at least one of the one or more conductive body surface patches and the proximal electrode, wherein the second voltage signal arises from the applied second current signal. The length of the distal expandable member is determined based at least partially on the second voltage signal, The catheter positioning system according to embodiment 11, further comprising commands to perform the following. (13) When the non-temporary computer-readable medium is executed by the processor, the processor: Comparing the aforementioned length with the longitudinal threshold, When the length exceeds the longitudinal threshold, an output is provided indicating a change in the shape of the distal expandable member. The catheter positioning system according to embodiment 10, further comprising commands to perform the following. (14) When the non-temporary computer-readable medium is executed by the processor, the processor: Comparing the aforementioned length with the minimum re-covering length, When the aforementioned length increases and exceeds the minimum re-covering length, a low flow rate to the distal expandable member is triggered, thereby preventing the initiation of a high flow rate and expansion of the distal expandable member. The catheter positioning system according to embodiment 13, further comprising commands to perform the following. (15) When the non-temporary computer-readable medium is executed by the processor, the processor: When the length decreases to below the longitudinal threshold, a high flow rate is permitted to inflate the distal expandable member. The catheter positioning system according to embodiment 13, further comprising commands to perform the following.

[0081] (16) When the non-temporary computer-readable medium is executed by the processor, the processor: To determine the expansion radius of the distal expandable member, The catheter positioning system according to embodiment 13, further comprising commands to perform the following. (17) When the non-temporary computer-readable medium is executed by the processor, the processor: Comparing the aforementioned expansion radius with the radial threshold, When the expansion radius exceeds the radial threshold, an output is provided indicating a change in the shape of the distal expandable member. The catheter positioning system according to embodiment 16, further comprising commands to perform the following. (18) When the non-temporary computer-readable medium is executed by the processor, the processor: The system is fixed to the distal expandable member and receives one or more sensor signals from sensors spaced radially apart around the distal expandable member. The expansion radius is determined based at least partially on one or more of the aforementioned sensor signals, The catheter positioning system according to embodiment 17, further comprising commands to perform the following. (19) When the non-temporary computer-readable medium is executed by the processor, the processor: Comparing the aforementioned length with the aforementioned longitudinal threshold, Comparing the aforementioned expansion radius with the aforementioned radial threshold, When the length is greater than the longitudinal threshold and the expansion radius is smaller than the radial threshold, the output is provided to indicate that the catheter is sufficiently compressed to cover the area. The catheter positioning system according to embodiment 17, further comprising commands to perform the following. (20) The catheter positioning system according to Embodiment 19, wherein the radial threshold is at least partially based on re-coverage force calculation.

Claims

1. It is a catheter, A shaft extending along the longitudinal axis of the catheter, An expandable member positioned close to the distal end of the shaft and movable from an expanded configuration to a collapsed configuration, having a longitudinal dimension parallel to the longitudinal axis that increases when the expandable member moves from the expanded configuration to the collapsed configuration, and the expandable member comprises a balloon, A distal sensor fixed to the distal portion of the expandable member, Processor and A non-temporary computer-readable medium that communicates with the processor, and when executed by the processor, the processor (a) Applying a first current signal between one or more conductive body surface patches and the distal sensor, (b) Measuring a first voltage signal between at least one of the one or more conductive body surface patches and the distal sensor, wherein the first voltage signal is generated from the applied first current signal, (c) Determining the length of the expandable member based at least partially on the first voltage signal, (d) Comparing the length with the longitudinal threshold, (e) When the length exceeds the longitudinal threshold, provide an output indicating a change in the shape of the expandable member, (f) (i) Compare the length with a minimum re-covering length which is the length over which the catheter can be re-covered with the minimum acceptable risk of damage, and if the length increases and exceeds the minimum re-covering length, trigger a low flow rate to the expandable member to prevent a high flow rate from being initiated and the expandable member from expanding, or (ii) if the length decreases to below the longitudinal threshold, allow a high flow rate to expand the expandable member, A non-temporary computer-readable medium having an instruction to perform the following: A catheter equipped with [a specific feature / equipment].

2. The system further comprises a proximal sensor fixed to the shaft in the proximal direction relative to the distal sensor, wherein when the expandable member moves from the expanded configuration to the collapsed configuration, the distal sensor moves distally away from the proximal sensor. The catheter according to claim 1, wherein the distal sensor is positioned relative to the proximal sensor and indicates the longitudinal dimension of the expandable member.

3. The catheter according to claim 2, further comprising a navigation sensor fixed to the shaft of the catheter in close proximity to the proximal sensor.

4. The catheter according to claim 1, further comprising an expandable member that engages with the shaft and the expandable member, and is configured to slide along the longitudinal axis relative to the shaft to shorten and extend the longitudinal dimension of the expandable member, wherein the distal sensor is fixed in close proximity to the distal end of the expandable member.

5. The catheter according to claim 1, further comprising a main body sensor fixed to the expandable member and positioned to indicate the radial dimension of the expandable member, wherein the radial dimension is perpendicular to the longitudinal axis and decreases when the expandable member moves from the expanded configuration to the collapsed configuration.

6. The main sensor comprises one or more conductive coils, and each of the one or more conductive coils is configured as a magnetic sensor. The expandable member comprises an expandable membrane, The catheter according to claim 5, wherein each of the one or more conductive coils is disposed on the outer surface of the expandable membrane.

7. The catheter according to claim 1, further comprising a triphiler wire having three traces, including two copper traces and one constantan trace, wherein one of the three traces is electrically connected to the distal sensor.

8. A catheter positioning system, Processor and A non-temporary computer-readable medium that communicates with the processor, and when executed by the processor, the processor (a) Applying a first current signal between one or more conductive body surface patches and a probe electrode, wherein the probe electrode is fixed to a distal expandable member of a catheter configured to be inserted into the patient's body, and the distal expandable member comprises a balloon. (b) Measuring a first voltage signal between at least one of the one or more conductive body surface patches and the probe electrode, wherein the first voltage signal is generated from the applied first current signal, (c) Determining the length of the distal expandable member based at least partially on the first voltage signal, (d) Comparing the length with the longitudinal threshold, (e) When the length exceeds the longitudinal threshold, provide an output indicating a change in the shape of the distal expandable member, (f) (i) Compare the length with a minimum re-covering length which is the length over which the catheter can be re-covered with the minimum acceptable risk of damage, and if the length increases and exceeds the minimum re-covering length, trigger a low flow rate to the distal expandable member to prevent a high flow rate from being initiated and the distal expandable member from expanding, or (ii) if the length decreases to below the longitudinal threshold, allow a high flow rate to expand the distal expandable member, A non-temporary computer-readable medium having an instruction to perform the following: A catheter positioning system equipped with the following features.

9. When the non-temporary computer-readable medium is executed by the processor, the processor: The position of the proximal electrode, which is fixed to the catheter and positioned proximal to the probe electrode, is determined. The length of the distal expandable member is determined based at least partially on the position of the proximal electrode, The catheter positioning system according to claim 8, further comprising a command to perform the following.

10. When the non-temporary computer-readable medium is executed by the processor, the processor: Applying a second current signal between at least one of the one or more conductive body surface patches and the proximal electrode, Measuring a second voltage signal between at least one of the one or more conductive body surface patches and the proximal electrode, wherein the second voltage signal is generated from the applied second current signal. The length of the distal expandable member is determined based at least partially on the second voltage signal, The catheter positioning system according to claim 9, further comprising a command to perform the following.

11. When the non-temporary computer-readable medium is executed by the processor, the processor: To determine the expansion radius of the distal expandable member, The catheter positioning system according to claim 8, further comprising a command to perform the following.

12. When the non-temporary computer-readable medium is executed by the processor, the processor: Comparing the aforementioned expansion radius with the radial threshold, When the expansion radius exceeds the radial threshold, an output is provided indicating a change in the shape of the distal expandable member. The catheter positioning system according to claim 11, further comprising a command to perform the following.

13. When the non-temporary computer-readable medium is executed by the processor, the processor: The system is fixed to the distal expandable member and receives one or more sensor signals from sensors spaced radially apart around the distal expandable member. The expansion radius is determined based at least partially on one or more of the sensor signals, The catheter positioning system according to claim 12, further comprising a command to perform the following.

14. When the non-temporary computer-readable medium is executed by the processor, the processor: Comparing the aforementioned expansion radius with the aforementioned radial threshold, When the length is greater than the longitudinal threshold and the expansion radius is smaller than the radial threshold, the output is provided to indicate that the catheter is sufficiently compressed to cover the area. The catheter positioning system according to claim 12, further comprising a command to perform the following.

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