Detecting balloon catheter tissue contact using optical measurements

Abstract

To provide a medical system.SOLUTION: The medical system includes a catheter, a light source, a detector, a circulator, and a processor. The catheter includes a distal-end assembly for performing a medical operation on tissue in a cavity of an organ of a patient, the distal-end assembly including an optical fiber configured to guide transmitted light to interact with the tissue of the cavity, and to guide returned light that interacted with the tissue. The light source is configured to produce the transmitted light. The detector is configured to measure the returned light. The circulator is configured to couple the transmitted light from the light source to the optical fiber, and to couple the returned light from the optical fiber to the detector. The processor is configured to identify contact of the distal-end assembly with the tissue based on the returned light measured by the detector, and to indicate the identified contact to a user.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to medical devices, and more particularly to a method and system for detecting contact between a catheter and tissue. [Background technology]

[0002] Various techniques for verifying catheter contact with tissue have been proposed in the patent literature. For example, U.S. Patent No. 8,025,661 describes a cardiac ablation device including a catheter body and a teardrop-shaped balloon connected to the catheter body. The device further includes a radiant energy emitter axially movable within a central lumen of the catheter body. A radiant energy transparent body surrounds the energy emitter and includes a plurality of illumination fibers circumferentially disposed around the energy emitter. A detector is in communication with the contact-sensing element and configured to determine the amount of at least one color component of the reflected light. The amount of the at least one color component indicates contact between the balloon and the target tissue site.

[0003] As another example, U.S. Patent No. 10,136,945 describes a device and method for providing and using an ablation catheter. The catheter includes an expandable member having a plurality of electrodes, each associated with at least one contact sensor and at least one light emitting element. Light is emitted in response to contact of the contact sensors with the tissue to be ablated. A light sensor disposed centrally relative to the catheter collects the light emitted from the light emitting elements and transmits a signal to a system controller for display.

[0004] U.S. Patent No. 10,682,179 describes an ablation and visualization system and method for determining contact between a catheter and tissue. In some embodiments, a method for monitoring tissue ablation is provided, the method including: advancing a distal tip of an ablation catheter into tissue requiring ablation; illuminating the tissue with UV light to excite NADH in the tissue, wherein the tissue is illuminated radially, axially, or both; determining from the level of NADH fluorescence in the illuminated tissue when the distal tip of the catheter is in contact with the tissue; and delivering ablation energy to the tissue to form a lesion in the tissue. Summary of the Invention [Means for solving the problem]

[0005] Embodiments of the invention described below provide a medical system including a catheter, a light source, a detector, a circulator, and a processor. The catheter includes a distal tip assembly for performing a medical procedure on tissue within a cavity of a patient's organ, the distal tip assembly including an optical fiber configured to guide transmitted light to interact with the tissue of the cavity and to guide returned light that has interacted with the tissue. The light source is configured to generate the transmitted light. The detector is configured to measure the returned light. The circulator is configured to couple the transmitted light from the light source to the optical fiber and the returned light from the optical fiber to the detector. The processor is configured to identify contact of the distal tip assembly with the tissue based on the returned light measured by the detector and to indicate the identified contact to a user.

[0006] In some embodiments, the processor is configured to identify a touch based on a change in the measured intensity of the returned light.

[0007] In some embodiments, the processor is configured to establish a baseline value for the intensity of the returned light while the distal tip assembly is not in contact with tissue, and to identify changes relative to the baseline value.

[0008] In one embodiment, the distal end of the fiber includes one of an optical diffusing element and an optical diffractive element configured to couple transmitted light from the fiber and couple returned light that has interacted with the tissue back into the fiber.

[0009] In some embodiments, the diffractive optical element comprises an optical grating coupler.

[0010] In other embodiments, the distal end of the fiber includes an opaque termination of the fiber. In yet other embodiments, the distal tip assembly includes an expandable transparent membrane.

[0011] In one embodiment, the transparent membrane includes a plurality of ablation electrodes disposed thereon, and the processor is configured to output a recommendation for performing a medical procedure using the electrodes based on identifying contact with tissue.

[0012] In some embodiments, the light source, detector, and circulator are mounted in a distal tip assembly.

[0013] In some embodiments, the light source is a Light Emitting Diode (LED).

[0014] According to another embodiment of the present invention, there is further provided a method for performing a medical operation on tissue within a cavity of an organ of a patient, the method comprising inserting a catheter distal tip assembly into the cavity. Transmitted light is directed through an optical fiber within the distal tip assembly to interact with the tissue of the cavity. Return light that has interacted with the tissue is directed through the same optical fiber. Contact of the distal tip assembly with the tissue is identified based on the returned light measured by a detector, and the identified contact is indicated to a user.

[0015] The present invention will be more fully understood from the following detailed description taken in conjunction with the drawings, in which: [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic, pictorial illustration of a catheter-based diagnostic and / or ablation system comprising a permeable balloon catheter, in accordance with an embodiment of the present invention; [Figure 2] 2 is a schematic, pictorial illustration of the permeable balloon catheter and contact detection module of FIG. 1, in accordance with one embodiment of the present invention; [Figure 3] 2 is a schematic, pictorial illustration of a fiber grating coupler within the transparent membrane of the balloon catheter of FIG. 1, in accordance with one embodiment of the present invention. [Figure 4] 2 is a flow chart that schematically illustrates a method for detecting tissue in contact with the permeable balloon catheter of FIG. 1, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Overview During catheterization procedures of body organs, such as cardiac electroanatomical mapping and / or ablation, it may be necessary to ensure that electrodes disposed on an expandable membrane coupled to the distal end of a probe, such as a catheter, are in physical contact with the wall tissue of a cavity of the organ, such as the wall tissue of a cardiac chamber.

[0018] The embodiments of the invention described below provide a system in which a distal tip assembly of a catheter emits light into a surrounding medium and includes means for collecting light that interacts with the surrounding medium, such as light reflected and / or scattered by wall tissue of an organ cavity.

[0019] The disclosed technology can be used with a variety of distal tip assemblies. For example, the distal tip assembly may include an expandable frame such as those used in balloon and basket catheters, or other frames such as basket, lasso, multi-arm, and tip catheters. In the case of an expandable frame, the distal tip assembly may include a permeable expandable membrane (the remainder of which is mostly covered by the electrodes, for example, of a balloon or basket catheter).

[0020] In one embodiment, an optical fiber is mounted within the expandable frame and is used to transmit light from an external light source, such as a light-emitting diode (LED). The same optical fiber is used to carry the return light that interacts with the wall tissue of the cavity to an external detector (e.g., a photodiode). The distal end of the fiber, located inside the transparent expandable membrane of the distal tip assembly, includes a coupler, such as a grating coupler or diffuser, configured to emit the transmitted light and couple the return light into the fiber.

[0021] An optical circulator is coupled at the proximal end of the optical fiber to separate the returning light from the transmitted light. Measurements from a detector (e.g., a photodiode) are analyzed by a processor to indicate the occurrence of physical contact between the distal tip assembly and tissue (e.g., by analyzing changes in the intensity of the returning light). The LED, optical circulator, and photodiode may be in an external unit, hereinafter also referred to as a "contact detection module."

[0022] In another embodiment, the light source, detector, and circulator are attached to the distal tip assembly. For example, the LED, circulator, and photodiode can all be located inside a transparent expandable membrane. In this embodiment, an electrical signal is carried by a cable running through the catheter shaft to drive the LED and carry the measured electrical signal from the photodiode in the opposite direction to a processor.

[0023] In some embodiments, the processor provides a baseline intensity value by first measuring the intensity of the returned light while the catheter is in the blood pool but before the expandable membrane contacts tissue. When the transparent membrane contacts tissue, the intensity of the returned light changes relative to the baseline value, and the processor uses this change to perform contact detection.

[0024] In one embodiment, a system is provided comprising: (a) a catheter including a distal tip assembly for performing a medical operation on tissue within a cavity of a patient's organ, the distal tip assembly including an optical fiber configured to direct transmitted light to interact with tissue in the cavity and to return return light that has interacted with the tissue; (b) a light source configured to generate the transmitted light; (c) a detector configured to measure the returned light; (d) a circulator configured to couple the transmitted light from the light source to the optical fiber and to couple the returned light from the optical fiber to the detector; and (e) a processor configured to identify contact of the distal tip assembly with the tissue based on the returned light measured by the detector and to indicate the identified contact to a user.

[0025] By providing a single optical fiber-based tissue contact detection, the balloon catheter can have a smaller diameter, allowing for better shaft flexibility and improved maneuverability, and therefore improved access to several target body locations.

[0026] System Description 1 is a schematic, pictorial illustration of a catheter-based diagnostic and / or ablation system 20 comprising a permeable balloon catheter 40, according to one embodiment of the present invention. System 20 includes a catheter 21, the shaft 22 of which is inserted by a physician 30 through a sheath 23 and into the vascular system of a patient 28. The physician then navigates a distal end 22a of shaft 22 to a target location within the patient's heart 26.

[0027] In the embodiments described herein, the catheter 21 can be used for any suitable diagnostic and / or therapeutic purpose, such as electrophysiological sensing and / or irreversible electroporation (IRE) and / or radiofrequency (RF) ablation, to electrophysiologically isolate PV ostium 51 tissue in the left atrium 45 of the heart 26.

[0028] Once the distal end 22a of the shaft 22 reaches the target location, the physician 30 retracts the sheath 23 and expands the balloon 40, typically by pumping saline into the balloon 40. The physician 30 then manipulates the shaft 22 so that the electrodes 50 disposed on the balloon 40 catheter engage the inner walls of the PV ostium 51 and apply electrophysiological sensing and / or IRE and / or RF ablation to the ostium 51 tissue via the electrodes 50.

[0029] As seen in inset 25 and in more detail in FIG. 2, the expandable balloon 40 comprises a plurality of equidistant smooth-edged electrodes 50. The transparent membrane 44 of the balloon 40 allows for optical detection of contact with tissue, as described in FIG. 2. Due to the flat shape of the distal portion of the balloon 40, the distance between adjacent electrodes 50 remains approximately constant, even where the electrodes 50 cover the distal portion. Thus, when used for IRE, the configuration of the balloon 40 allows for more effective electroporation (e.g., having a substantially uniform field strength) between adjacent electrodes 50, while the smooth edges of the electrodes 50 minimize unwanted thermal effects.

[0030] In the context of this disclosure and in the claims, the term "approximately" with respect to any numerical value or range of values ​​indicates a suitable dimensional tolerance that allows a portion of a component or a collection of components to function in accordance with its intended purpose as described herein.

[0031] The proximal end of catheter 21 is connected to console 24, which includes an IRE pulse generator 38 configured to apply IRE pulses between adjacent electrodes 50. The electrodes are connected to IRE pulse generator 38 by electrical wiring that runs through shaft 22 of catheter 21. An optical tissue contact detection module 48 of console 24 is used in conjunction with balloon 40, as described in FIG.

[0032] An optical fiber (seen in Figure 2) runs through shaft 22 and is coupled at its proximal end to module 48. The distal end of the fiber includes a coupler (seen in Figure 2) that emits transmitted light and couples return light back into the fiber.

[0033] Console 24 comprises a processor 41, typically a general-purpose computer, with suitable front-end and interface circuitry 37 for receiving signals from catheter 21 and external electrodes 49, which are typically positioned around the chest of patient 28. To this end, processor 41 is connected to external electrodes 49 by wires running through cable 39.

[0034] During the procedure, the system 20 can track the position of each of the electrodes 50 within the heart 26 using the Active Current Location (ACL) method provided by Biosense-Webster (Irvine, California), described in U.S. Pat. No. 8,456,182, the disclosure of which is incorporated herein by reference.

[0035] In other embodiments, physician 30 can modify any of the parameters, such as the wavelength used by module 48, from user interface 47. User interface 47 may include any suitable type of input device, such as a keyboard, a mouse, or a trackball, among others.

[0036] Processor 41 is typically programmed in software to perform the functions described herein, such as analyzing signals acquired by module 48 to indicate the occurrence of contact of membrane 44 with tissue. The software may be downloaded to the computer in electronic form, for example over a network, or alternatively or additionally may be provided on and / or stored on a non-transitory tangible medium, such as magnetic, optical, or electronic memory.

[0037] In particular, processor 41 executes dedicated algorithms that enable processor 41 to perform the disclosed steps as disclosed herein, including in FIG. 4, and as further described below.

[0038] Detecting tissue contact with balloon catheters using optical measurements Figure 2 is a schematic, pictorial illustration of the permeable balloon catheter 40 and contact detection module 48 of Figure 1, in accordance with one embodiment of the present invention. The following description refers to balloon 40, but the techniques described below may be applied mutatis mutandis to any catheter having other types of expandable frames, such as, but not limited to, basket catheters.

[0039] Balloon 40 includes a transparent membrane 44 having electrodes 50 disposed on a surface of membrane 44. In some embodiments, when electrodes 50 are placed in contact with tissue of heart 26, electrodes 50 are configured to sense intracardiac electrical signals from the tissue and / or ablate the tissue.

[0040] In some embodiments, the electrode 50 is configured to apply ablation pulses to tissue received from the IRE generator 38 and controlled by the processor 41 and / or by the physician 30, as described above in FIG. 1.

[0041] In the embodiment shown, catheter 40 further comprises an optical fiber 60 that passes through shaft 22 and terminates at an optical coupler 66 within the interior volume of balloon 40. Light emitted by coupler 66 propagates within the saline solution used to inflate balloon 40 and interacts with media outside membrane 44, such as blood and / or wall tissue (seen in FIG. 1 ).

[0042] The light emitted by coupler 66 is generated by a light source (e.g., an LED) 202 within unit 48 and transmitted to fiber 60 using circulator 204. Returning light is transmitted by circulator 204 to photodetector 206. The use of a circulator therefore allows for the separation of the incident light from the returning light, thereby enabling the detection of even small changes in the intensity of the returning light due to physical contact of transparent membrane 44 with the wall tissue.

[0043] The returned light measured by the photodetector 206 is conveyed as an electrical signal to the processor 41, which performs the analysis necessary to determine the occurrence of membrane contact with wall tissue, as described above.

[0044] The configuration shown in Figure 2 is provided as an example. The principles described herein may be applied to other types of ablation catheters as well, such as basket-type distal ends with transparent membranes attached to expandable frames. Various types of couplers may also be used, such as those corrugated for emitting in several directions or those with surface roughness to scatter light.

[0045] Balloon catheter using optical grating coupler 3 is a schematic, pictorial illustration of a fiber grating coupler 366 within the transparent membrane 44 of the balloon catheter 40 of FIG. 1, in accordance with one embodiment of the present invention. As shown, the coupler 366 is patterned onto the optical fiber 360 at the distal end of the fiber 360, which terminates in an opaque termination, to minimize reflected light.

[0046] With proper selection of the coupler 366 parameters, it can be very efficient. Specifically, by adjusting the grating's groove area and length, the grating's coupling coefficient can be maximized. In this way, a large fraction (e.g., >30%) of the incident light intensity can be coupled to interact with the surrounding medium.

[0047] The direction in which light is coupled by coupler 366 into the surrounding medium 300, and the direction in which the interacted light is coupled back into fiber 360 from there, is determined by an angle θ given by the diffraction grating equation: m is defined as:

[0048]

number

[0049] The configuration shown in Figure 3 is provided as an example. Other embodiments may induce a more uniform emission of light over film 44 in other ways (e.g., multi-period gratings or roughening).

[0050] Method for detecting tissue contact with a balloon catheter using optical measurements - Patent Application 20070122997 4 is a flow chart that schematically illustrates a method for detecting tissue in contact with the permeable balloon catheter 40 of FIG. 1, in accordance with one embodiment of the present invention. The algorithm according to the presented embodiment executes a process that begins when the physician 30 navigates the balloon catheter 40 to the location of the target tissue within the patient's organ, such as the PV ostium 51, using, for example, electrode 50 as an ACL sensing electrode and bringing the membrane 44 of the expanded balloon 40 into contact with the ostial tissue at catheter placement step 402.

[0051] In this process, unit 48 uses coupler 360 (seen in FIG. 3 ) to transmit the emitted light inside the cavity to interact with the surrounding medium, possibly including wall tissue in contact with membrane 44, in transmitted light emission step 404.

[0052] In an acquisition step 406 , unit 48 acquires and measures return light from the surrounding medium, possibly including wall tissue in contact with membrane 44 .

[0053] At a check step 408, processor 41 checks whether a change in the intensity of the returned light has occurred, for example to the extent that it indicates a touch.

[0054] If the answer is no, the processor issues an indication of insufficient contact made with the wall tissue (410), for example as a text message on a display, and the process returns to step 402.

[0055] If the answer is yes, the processor issues an indication that sufficient contact has been made with the wall tissue 412. In an optional embodiment, the processor may further issue a notification that the balloon is in position for ablation 414.

[0056] Although the embodiments described herein primarily address cardiac applications, the methods and systems described herein may also be used in other medical applications, such as neurological and ENT.

[0057] Accordingly, it will be understood that the above-described embodiments are cited by way of example, and that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the foregoing specification, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description. Documents incorporated by reference into this patent application shall be deemed an integral part of this application, except that to the extent that any term is defined in these incorporated documents in a manner that is inconsistent with a definition expressly or impliedly made herein, only the definition in this specification shall be considered.

[0058] [Embodiment] (1) A health care system: a catheter for performing a medical operation on tissue within a cavity of an organ of a patient, the catheter including a distal tip assembly, the distal tip assembly including an optical fiber configured to direct transmitted light to interact with the tissue of the cavity and to direct return light that has interacted with the tissue; a light source configured to generate the transmitted light; a detector configured to measure the returned light; a circulator configured to couple the transmitted light from the light source into the optical fiber and to couple the returned light from the optical fiber to the detector; a processor configured to identify contact of the distal tip assembly with the tissue based on the returned light measured by the detector and to indicate the identified contact to a user. (2) The medical system of embodiment 1, wherein the processor is configured to identify the contact based on a change in the measured intensity of the returned light. (3) The medical system of embodiment 2, wherein the processor is configured to establish a baseline value of the intensity of the returned light while the distal end assembly is not in contact with the tissue and identify changes relative to the baseline value. (4) The medical system of embodiment 1, wherein the distal end of the fiber includes one of an optical diffusing element and an optical diffractive element configured to couple the transmitted light from the fiber and couple the return light that has interacted with the tissue back into the fiber. (5) The medical system of embodiment 4, wherein the optical diffractive element includes an optical grating coupler.

[0059] (6) A medical system as described in embodiment 4, wherein the distal end of the fiber includes an opaque termination of the fiber. (7) A medical system as described in embodiment 1, wherein the distal end assembly includes an expandable transparent membrane. (8) The medical system of embodiment 7, wherein the transparent membrane includes a plurality of ablation electrodes disposed thereon, and the processor is configured to output a recommendation for performing the medical procedure using the electrodes based on identifying the contact with the tissue. (9) A medical system as described in embodiment 1, wherein the light source, the detector, and the circulator are attached to the distal end assembly. (10) The medical system of embodiment 1, wherein the light source is a light-emitting diode (LED).

[0060] (11) A method comprising: inserting a catheter distal end assembly into a cavity of a patient's organ to perform a medical operation on tissue within the cavity; directing transmitted light within an optical fiber within the distal tip assembly to interact with the tissue in the cavity; directing the return light that has interacted with the tissue through the same optical fiber; and identifying contact of the distal tip assembly with the tissue based on the returned light measured by a detector, and indicating the identified contact to a user. (12) The method of embodiment 11, wherein identifying the contact includes identifying a change in the measured intensity of the returned light. (13) The method of embodiment 11, comprising using one of an optical diffusing element and an optical diffractive element to couple the transmitted light from the distal end of the fiber and couple the return light that has interacted with the tissue back to the distal end of the fiber.

Claims

1. 1. A health care system comprising: a catheter including a distal tip assembly for performing a medical operation on tissue within a cavity of an organ of a patient, the distal tip assembly including an optical fiber configured to direct transmitted light to interact with the tissue within the cavity and to direct return light that has interacted with the tissue; a light source configured to generate the transmitted light; a detector configured to measure the returned light; a circulator configured to couple the transmitted light from the light source into the optical fiber and to couple the returned light from the optical fiber to the detector; a processor configured to identify contact of the distal tip assembly with the tissue based on the returned light measured by the detector and to indicate the identified contact to a user; the processor is configured to identify the contact based on a change in the measured intensity of the returned light; The processor is configured to establish a baseline value for the intensity of the returned light while the distal tip assembly is not in contact with the tissue, and to identify changes relative to the baseline value.

2. A medical system, comprising: a catheter including a distal tip assembly for performing a medical operation on tissue within a cavity of an organ of a patient, the distal tip assembly including an optical fiber configured to direct transmitted light to interact with the tissue within the cavity and to direct return light that has interacted with the tissue; a light source configured to generate the transmitted light; a detector configured to measure the returned light; a circulator configured to couple the transmitted light from the light source into the optical fiber and to couple the returned light from the optical fiber to the detector; a processor configured to identify contact of the distal tip assembly with the tissue based on the returned light measured by the detector and to indicate the identified contact to a user; the distal end of the optical fiber includes an optical diffractive element configured to couple the transmitted light from the optical fiber and to couple the returned light that has interacted with the tissue back into the optical fiber; The medical system, wherein the diffractive optical element includes an optical grating coupler having a light outlet formed in a grating pattern.

3. A medical system, a catheter including a distal tip assembly for performing a medical operation on tissue within a cavity of an organ of a patient, the distal tip assembly including an optical fiber configured to direct transmitted light to interact with the tissue within the cavity and to direct return light that has interacted with the tissue; a light source configured to generate the transmitted light; a detector configured to measure the returned light; a circulator configured to couple the transmitted light from the light source into the optical fiber and to couple the returned light from the optical fiber to the detector; a processor configured to identify contact of the distal tip assembly with the tissue based on the returned light measured by the detector and to indicate the identified contact to a user; the distal end of the optical fiber includes one of an optical diffusing element and an optical diffractive element configured to couple the transmitted light from the optical fiber and to couple the returned light that has interacted with the tissue back into the optical fiber; The medical system, wherein the distal end of the optical fiber includes an opaque termination of the optical fiber.

4. The medical system of claim 1 , wherein the distal end assembly includes an expandable transparent membrane.

5. The medical system of claim 1 , wherein the light source, the detector, and the circulator are attached to the distal end assembly.

6. The medical system of claim 1 , wherein the light source is a light emitting diode (LED).

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