Method and system for identifying electrode-tissue contact - Patent application

Abstract

The present invention discloses a method and system for identifying contact between an electrode and tissue. In the method (700) for identifying contact between an electrode and tissue, impedance between electrodes in a body cavity invasive device is collected at different frequencies (S710). Based on the collected impedance between the electrodes, an impedance-frequency response coefficient between the electrodes is determined (S720). Based on the impedance-frequency response coefficient, a contact state between the electrode and tissue in the body cavity is determined (S730). The body cavity invasive device of the present invention includes a catheter. Several electrodes are provided at the distal end of the invasive catheter. The contact state includes whether the electrodes are in contact with the surface of the body cavity and the degree of contact.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to a Chinese patent application having a filing date of May 17, 2022, application number 202210541390.8, and title "Method and system for identifying contact between an electrode and tissue," the entire contents of which are incorporated by reference into the disclosure of this application.

[0002] Technical Field The present invention relates to electrophysiological ablation and circuits, and in particular to methods and systems for identifying electrode-tissue contact. [Background technology]

[0003] Currently, medical 3D localization systems are often used to locate one or more invasive devices and to determine the relative location of the invasive device and tissue of interest. For example, in practice, there is a need to locate the invasive device within a body cavity, and in particular to identify contact between the invasive device and the surface of the body cavity. Generally, there is a need to evaluate contact between the invasive device and the surface of the body cavity within a cardiac chamber or renal artery. More specifically, there is a need to determine whether the invasive device is in contact with tissue.

[0004] A 3D localization system with contact indication function can more accurately reflect the relative positional relationship between an invasive device and the inner surface of a body cavity. Applications of contact indication using a medical 3D localization system include contact indication between a catheter and a heart chamber wall and / or a blood vessel wall, and contact indication between a catheter and an inner wall of a renal artery blood vessel.

[0005] Common invasive devices include, for example, a catheter, sheath, or needle with one or more localization electrodes attached. Catheters can be classified according to their appearance, for example, basket catheters, balloon catheters, ring catheters, petal catheters, lattice catheters, wire catheters, etc.

[0006] Therefore, there is a need for a method and system for determining the relative position and degree of contact between an invasive device and the tissue of interest that is easy to operate in practice. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide a system and method for identifying the location of an invasive device in a body cavity, and in particular relates to a method and system for identifying contact between an invasive device and a body cavity surface, and non-exclusively relates to a method and system for evaluating contact between an invasive device and a body cavity surface in a cardiac chamber or a renal artery. The invasive device according to the present invention non-exclusively relates to basket-type, balloon-type, ring-type, petal-type, lattice-type, wire-type invasive devices using similar principles. [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided a method for identifying contact between an electrode and tissue, which may include collecting impedance between electrodes of a body cavity invasive device at different frequencies, determining an impedance-frequency response coefficient between the electrodes based on the collected impedance between the electrodes, and determining a contact state between the electrode and tissue in the body cavity based on the impedance-frequency response coefficient.

[0009] Preferably, the electrodes include a working electrode and a reference electrode. In the method according to the first aspect of the invention, collecting impedance between the electrodes at different frequencies may include collecting impedance between the working electrode, between the reference electrode and between the working and reference electrodes at different frequencies.

[0010] Preferably, the working electrode may include an ablation electrode.

[0011] In the method according to the first aspect of the present invention, determining a contact state between the electrode and tissue in the body cavity may preferably include determining a contact state between a working electrode and tissue in the body cavity.

[0012] Preferably, the body cavity invasive device may include a catheter, and the electrode is provided at a distal end of the catheter.

[0013] Preferably, the catheter may include at least one of a basket-type catheter, a balloon-type catheter, a ring-type catheter, a petal-type catheter, a lattice-type catheter, and a wire-type catheter.

[0014] Preferably, different frequencies may be selected in response to different responses due to different tissue impedances to the frequencies.

[0015] Preferably, the frequency range of the different frequencies may be 500 Hz to 100 kHz.

[0016] Preferably, the different frequencies may be two different frequencies.

[0017] In the method according to the first aspect of the present invention, determining an impedance-frequency response coefficient between the electrodes may comprise calculating an impedance-frequency response coefficient between the working electrode and an impedance-frequency response coefficient between the reference electrode in accordance with equations (1) and (2), respectively; Impedance frequency response coefficient Coef between working electrodes i and j ij teeth,

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[0018] Preferably, the Base ij Parameter and Base mn Parameter and Dis ij Parameters and Dis mn There may be a correlation between the parameters.

[0019] Preferably, the Base ij Parameter and Base mn The parameters are ij Parameters and Dismn The parameter may be obtained by performing a high order regression modeling analysis with the electrode width parameter and the electrode diameter parameter.

[0020] Preferably, the weighting factor a ij , b ij , c ij , a mn , b mn , c mn The magnitude of may reflect the weight of the impedance characteristics, capacitive reactance characteristics, and overall resistance and capacitance characteristics of the tissue or blood between the electrodes in the usage environment, provided that a ij +b ij +c ij =1,a mn +b mn +c mn =1.

[0021] In the method according to the first aspect of the present invention, preferably, the method may further include displaying a contact state between the electrode and tissue in the body cavity by using different colors.

[0022] According to a second aspect of the present invention, there is provided a system for identifying contact between an electrode and tissue, which may include a collection unit for collecting impedance between electrodes in a body cavity invasive device at different frequencies, an impedance-frequency response coefficient determination unit for determining an impedance-frequency response coefficient between the electrodes based on the collected impedance between the electrodes, and a contact state determination unit for determining a contact state between the electrode and tissue in the body cavity based on the impedance-frequency response coefficient.

[0023] Preferably, the electrodes may include a working electrode and a reference electrode. In the system according to the second aspect of the invention, the collection unit may be configured to collect impedances between the working electrode, between the reference electrode, and between the working electrode and the reference electrode at different frequencies.

[0024] Preferably, the working electrode may include an ablation electrode.

[0025] In the system according to the second aspect of the present invention, the contact condition determining unit may preferably be configured to determine a contact condition between a working electrode and tissue in a body cavity.

[0026] Preferably, the body cavity invasive device includes a catheter, and the electrode may be provided at a distal end of the catheter.

[0027] Preferably, the catheter may include at least one of a basket-type catheter, a balloon-type catheter, a ring-type catheter, a petal-type catheter, a lattice-type catheter, and a wire-type catheter.

[0028] Preferably, different frequencies may be selected in response to different responses due to different tissue impedances to the frequencies.

[0029] Preferably, the different frequencies may be in a frequency range of 500 Hz to 100 kHz.

[0030] Preferably, the different frequencies may be two different frequencies.

[0031] In the system according to the second aspect of the present invention, the impedance-frequency response coefficient determination unit may be configured to calculate an impedance-frequency response coefficient between the working electrode and an impedance-frequency response coefficient between the reference electrode according to Equation (1) and Equation (2), respectively; Impedance frequency response coefficient Coef between working electrodes i and j ij teeth,

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[0032] Preferably, the Base ij Parameter and Base mn Parameter and Dis ij Parameters and Dis mn There may be a correlation between the parameters.

[0033] Preferably, the Base ij Parameter and Base mn The parameters are ij Parameters and Dis mnThe parameter may be obtained by performing a high order regression modeling analysis with the electrode width parameter and the electrode diameter parameter.

[0034] Preferably, the weighting factor a ij , b ij , c ij , a mn , b mn , c mn The magnitude of may reflect the weight of the impedance characteristics, capacitive reactance characteristics, and overall resistance and capacitance characteristics of the tissue or blood between the electrodes in the usage environment, provided that a ij +b ij +c ij =1,a mn +b mn +c mn =1.

[0035] In the system according to the second aspect of the present invention, preferably, the system may further include a display unit for displaying a contact state between the electrode and tissue in the body cavity by using different colors.

[0036] According to a third aspect of the present invention there is provided a computer readable medium having stored thereon instructions executable by a processor which, when executed by the processor, cause the processor to perform a method for identifying contact between an electrode and tissue according to the first aspect of the present invention. Effect of the Invention

[0037] The present invention discloses a method and system for identifying contact between an invasive device and a body cavity surface in the field of locating an invasive device in a body cavity. The system includes an invasive catheter having several electrodes disposed at a distal end. The system collects impedance information of the electrodes at multiple reference frequencies, obtains a frequency response coefficient of the electrodes based on the impedance information at the multiple frequencies, and obtains a contact index (also called an adhesion index) CI based on an indication of the frequency response coefficient. The CI indicates whether the electrodes are in contact with the body cavity surface and the degree of contact. [Brief description of the drawings]

[0038] The present disclosure includes drawings which are to be considered incorporated in and constitute a part of the specification, and which, together with the specification, illustrate various exemplary embodiments, features, and aspects of the disclosure and serve to explain the principles of the disclosure. The present invention will be more fully understood by reference to the following detailed description and drawings, in which like elements are numbered alike.

[0039] [Figure 1] FIG. 1 illustrates the dielectric constant of blood, blood vessels, and the heart at different frequencies. [Diagram 2] FIG. 1 illustrates the conductivity of blood, blood vessels, and the heart at different frequencies. [Figure 3A] FIG. 1 is a schematic diagram of a ring-type invasive catheter. [Figure 3B] FIG. 1 is a schematic diagram of application of a ring-type invasive catheter. [Figure 4A] FIG. 1 is a schematic diagram of a petal-shaped invasive catheter. [Figure 4B] FIG. 1 is a schematic diagram of application of a petal-shaped invasive catheter. [Diagram 5] 4 is a flow chart of a method for identifying electrode-tissue contact in accordance with a preferred embodiment of the present invention. [Figure 6] FIG. 13 is a schematic diagram showing a display of a contact identification result. [Figure 7] 4 is a flow chart of a method for identifying contact between an electrode and tissue according to an embodiment of the present invention. [Figure 8] FIG. 1 is a schematic block diagram of a system for identifying electrode-tissue contact in accordance with an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The solution of the present invention will be described in more detail below with reference to the examples and drawings, but the present invention is not limited to the following examples.

[0041] Various exemplary embodiments, features, and aspects of the present disclosure are described in detail below with reference to the drawings, in which like reference numerals indicate elements having the same or similar functions, and in which various aspects of the embodiments are illustrated, but which are not necessarily drawn to scale unless specifically indicated.

[0042] The term "exemplary" herein means "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior over other embodiments.

[0043] In addition, in order to better explain the present disclosure, many specific details are described in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can be similarly implemented without some of the specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art are not described in detail in order to emphasize the gist of the present disclosure.

[0044] In general, the present invention provides a method and system for identifying electrode-tissue contact that is based on the principle that different biological tissue impedances provide different responses to frequency.

[0045] Since this involves impedance, it is necessary to collect or measure impedance. Hereinafter, "collect" and "measure" can be used interchangeably. Collecting or measuring impedance means obtaining a numerical value for impedance.

[0046] The method of collecting impedance may include, but is not limited to, collecting impedance between electrodes, between electrodes and a reference, or between references at different frequencies. Here, the electrode refers to an electrode in an invasive device, such as an ablation electrode, a monitoring electrode, and more specifically, a working electrode used for actual treatment or detection. The reference may be a ground level or a reference level outside the body cavity. The reference may be a reference electrode. In the following, the electrodes may be classified as working electrodes and reference electrodes to distinguish between electrodes and references. In the case of treatment using an invasive device, the working electrode in the invasive device may be called a treatment electrode. Therefore, collecting impedance at different frequencies can be more specifically interpreted as collecting impedance between working electrodes, between reference electrodes, and between working electrodes and reference electrodes at different frequencies.

[0047] As mentioned above, when the invasive device is an ablation catheter, the working electrode may be an ablation electrode.

[0048] In embodiments where the invasive device is a catheter, the working and reference electrodes may both be located at the distal end of the catheter, although in some embodiments the reference electrode may be located elsewhere, such as outside the body.

[0049] The catheter may be any or at least one of a basket type catheter, a balloon type catheter, a ring type catheter, a petal type catheter, a lattice type catheter, and a wire type catheter.

[0050] In accordance with the present invention, the collected impedance information is used to determine a frequency response coefficient of the electrodes, which in a preferred embodiment includes a frequency response coefficient between the working electrode and a frequency response coefficient between the reference electrode.

[0051] Based on the frequency response coefficient of the electrode, it is possible to determine the contact state between the electrode and the tissue in the body cavity, for example, whether the electrode is in contact with the tissue wall of the body cavity and the degree of contact can be determined. The electrode for determining whether the electrode is in contact with the tissue in the body cavity is the working electrode.

[0052] Acquiring impedance at different frequencies includes time-multiplexed acquisition and frequency-multiplexed acquisition.

[0053] The time-shared collection may be a process as follows. When impedance information is collected at several (e.g., n) frequencies, impedance information at a first frequency, impedance information at a second frequency, and so on, are collected up to impedance information at the nth frequency. After this series of collections is completed, or after a certain time has elapsed, impedance information at the first frequency, then the first frequency, and then the second frequency, is collected up to impedance information at the nth frequency. In this manner, time-shared collection is performed in sequence.

[0054] In the following description of this application, frequency division acquisition is taken as an example.

[0055] The collection frequency can be selected based on the different responses of two or more types of tissue impedance to the frequency. FIG. 1 shows the relative dielectric constants of blood, blood vessels, and the heart at different frequencies. FIG. 2 shows the conductivity of blood, blood vessels, and the heart at different frequencies. A plurality of frequencies can be selected for collecting impedance, for example, within the range of 500 Hz to 100 kHz.

[0056] The acquisition frequency can be determined according to the actual scenario. For example, the scenario shown in Figures 1 and 2 is to identify the contact between the electrodes and tissues in the heart chambers and blood vessels, in which case, according to the different responses of the myocardium, blood vessel wall, and blood impedances to the frequency, the appropriate acquisition frequency is selected according to the principle of selecting a frequency that makes the difference between the three impedances as large as possible. Here, the larger difference can be understood as a higher resolution for tissue differentiation.

[0057] Those skilled in the art should appreciate that Figures 1 and 2 illustrate the principle of different responses due to different tissue impedances with respect to frequency, and in fact the two figures illustrate the same principle expressed in different ways, with Figure 1 being in terms of dielectric constant and Figure 2 being in terms of conductivity.

[0058] intrusion device In the following, the penetration device according to the present invention will be considered.

[0059] An invasive device, i.e., a body cavity invasive device, refers to a device that can penetrate into a body cavity.

[0060] In a preferred embodiment of the invention, the invasive device is an invasive catheter. An electrode is provided at the distal end of the invasive catheter. The invention aims to determine whether and to what extent an electrode (e.g., an ablation electrode) in the invasive catheter is in contact with tissue within a body cavity (e.g., a cavity wall or surface).

[0061] 3A and 3B are schematic diagrams of a ring-type invasive catheter and application of the ring-type invasive catheter, respectively.

[0062] When the invasive catheter is of the ring type as shown in FIG. 3A, the catheter 300 includes an operating handle 301, a catheter proximal end 302, a catheter distal end 303, a catheter body 304, a ring-shaped surface electrode (working electrode) 305, and reference electrodes 306, 307.

[0063] As shown in FIG. 3B, tissues or organs that may come into contact with or be close to the ring-shaped catheter when it enters a body cavity include the left atrial wall 308, the left atrial cavity 309, the right superior pulmonary vein 310, the right inferior pulmonary vein 311, the left inferior pulmonary vein 312, and the left superior pulmonary vein 313.

[0064] Figure 4A is a schematic diagram of a petal-shaped invasive catheter, and Figure 4B is a schematic diagram of application of the petal-shaped invasive catheter.

[0065] When the invasive catheter is of the petal type as shown in FIG. 4A, the catheter 400 includes an operating handle 401, a catheter proximal end 402, a catheter distal end 403, a petal edge 404, a retractable lever 405, a petal electrode (working electrode) 406, and a lever reference electrode 407.

[0066] As shown in FIG. 4B, tissues or organs that may come into contact with or be close to the petal-shaped catheter when it enters a body cavity include the left atrial wall 408, the left atrial cavity 409, the right superior pulmonary vein 410, the right inferior pulmonary vein 411, the left inferior pulmonary vein 412, and the left superior pulmonary vein 413.

[0067] Due to the design of the invasive catheter, the reference electrode does not contact tissue during most of the procedure, and therefore serves as a reference for whether the other electrode (the working electrode) is attached or not, making it more reliable compared to methods of detecting electrode-tissue contact based on statistical analysis of impedance or phase data.

[0068] 5 and 6 show in more detail the procedure for determining the contact state between the working electrode of an invasive device and tissue and the display of the results, as will be explained in more detail below.

[0069] Contact Identification Method In more general terms, a method for identifying electrode-tissue contact according to an embodiment of the present invention will now be described.

[0070] FIG. 7 is a flow chart of a method for identifying electrode-tissue contact according to an embodiment of the present invention.

[0071] As shown in FIG. 7, a method 700 for identifying electrode-tissue contact begins at step S710, where impedance between electrodes in a body cavity invasive device is collected at different frequencies.

[0072] In step S710, the different frequencies are selected according to different responses due to different tissue impedances to the frequencies. Typically, the different acquisition frequencies are in the frequency range of 500 Hz to 100 kHz. In a preferred embodiment, the different frequencies refer to two different frequencies.

[0073] The following describes an example of collecting impedance at two frequencies. A first impedance is collected at a first frequency, and a second impedance is collected at a second frequency. In practice, impedance information may be collected at more frequencies. Common impedance collection includes time-shared collection and frequency-shared collection. Although the process of time-shared collection has been described above, frequency-shared collection is adopted in the exemplary embodiment of the present application.

[0074] In a preferred embodiment of the present invention, impedance is collected for a ring-type catheter as shown in FIG. 3A. According to the method of the present invention, in step S710, impedance at a first frequency and impedance at a second frequency between adjacent electrodes 305 on the annular surface are collected, and impedance at a first frequency and impedance at a second frequency between reference electrodes 306 and 307 are collected. In particular, when designing the catheter, the relationship between the spacing between adjacent electrodes 305 and the electrode spacing between reference electrodes 306 and 307 is considered, for example, both of them are equal or proportional to each other, and this relationship can be used as a basis for a parameter to identify the contact between the electrode and the tissue later. The number of reference electrodes is not limited to two as described in the patent, and more than two reference electrodes may be arranged to create a linear or nonlinear relationship between the spacing between different reference electrodes and the impedance.

[0075] In another preferred embodiment of the present invention, impedance is collected for a petal-shaped catheter as shown in FIG. 4A. According to the method of the present invention, in step S710, the impedance at the first frequency and the impedance at the second frequency between adjacent electrodes 406 at the petal edge 404, which is an annular surface, are collected, and the impedance at the first frequency and the impedance at the second frequency between the reference electrodes 407 are collected. In particular, when designing the catheter, the relationship between the spacing between adjacent electrodes 406 and the electrode spacing between the reference electrodes 407 is taken into consideration, for example, both of them are equal or proportional to each other, and this relationship can be used as a basis for a parameter to identify the contact between the electrode and the tissue later. The reference electrodes are not limited to two as described in the patent, and more than two reference electrodes may be arranged on the telescopic lever 405 to create a linear or nonlinear relationship between the spacing between different reference electrodes and the impedance.

[0076] Returning to FIG. 7, and in step S720, an inter-electrode impedance-frequency response coefficient is determined based on the inter-electrode impedance collected in step S710.

[0077] Thereafter, in step S730 of FIG. 7, the contact state between the electrode and the tissue in the body cavity is determined based on the impedance-frequency response coefficient.

[0078] In step S730, in a preferred embodiment, it is necessary to determine the contact state between the working electrode (e.g., adjacent electrode 305 in the annular surface shown in FIG. 3A, or adjacent electrode 406 in the petal edge 404 which forms the annular surface shown in FIG. 4A) and the tissue in the body cavity, rather than the contact state between the reference electrode (e.g., reference electrodes 306, 307 shown in FIG. 3A, or lever reference electrode 407 shown in FIG. 4A) and the tissue in the body cavity.

[0079] Hereinafter, the operations of step S720 and step S730 in FIG. 7 performed in the preferred embodiment of the present invention will be described with reference to FIG.

[0080] Taking the case of collecting impedance at two frequencies to identify the contact between the electrode and tissue as an example, the specific process is shown in Figure 5.

[0081] FIG. 5 is a flow chart of a method for identifying electrode-tissue contact in accordance with a preferred embodiment of the present invention.

[0082] As shown in FIG. 5, a method 500 for identifying electrode-tissue contact begins at step 502 with collecting impedance at a first frequency and impedance at a second frequency between the electrodes as described above.

[0083] Then, in step 504, the impedance vs. frequency response coefficient between the working electrode is calculated. In step 506, the impedance vs. frequency response coefficient between the reference electrode is calculated. Next, in step 508, a contact index between the electrode and tissue is calculated. Finally, in step 510, an output is provided to display whether the electrode of the invasive catheter is in contact with the tissue and the degree of contact.

[0084] More specifically, the desired working electrode-tissue contact condition can be finally obtained according to the following calculation formula:

[0085] (1) Impedance between working electrodes i and j vs. frequency response coefficient

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[0086] There is a correlation between the Base parameter and the Dis parameter. ij Parameter and Base mn Parameter and Dis ij Parameters and Dis mn There is a correlation between the parameters.

[0087] Furthermore, the electrode parameters, such as the width W and diameter D, are also factors that affect the Base parameters. The Base parameters are specific parameters of the catheter and are input to the system as known parameters. Specifically, the Base parameters can be obtained by performing a high-order regression modeling analysis with the Dis, W, and D parameters. In other words, the Base parameters ij Parameter and Base mn The parameters are ij Parameters and Dis mn The parameters are obtained by performing high-order regression modeling analysis on the electrode width parameters and electrode diameter parameters.

[0088] Weighting factor a ij , b ij , c ij , a mn , b mn , c mn The magnitude of reflects the weight of the impedance characteristics, capacitive reactance characteristics, and overall resistance and capacitance characteristics of the tissue or blood between the electrodes in the usage environment, provided that a ij +b ij +c ij =1,a mn +b mn +c mn =1.

[0089] In step 510, based on a contact index (also called an attachment index) CI, it is determined whether the electrode is in contact with the tissue by comparing it with a preset threshold, and the degree of contact between the electrode and the tissue may be determined by comparing it with multiple preset thresholds.

[0090] Furthermore, the contact state between the electrode and the tissue in the body cavity may be displayed using different colors.

[0091] FIG. 6 is a schematic diagram showing a display of the contact recognition result.

[0092] As shown in Fig. 6, the screen 601 of the display 600 shows an indication of whether the electrodes are in contact with the tissue, the color of the electrodes 602 represents the degree of contact between the electrodes and the tissue, and the center portion 603 represents the current attachment tendency, i.e., which electrodes are attached to the tissue. Attachment and non-attachment are distinguished by different prominent colors, and an attachment index value that reflects the degree of contact between the electrodes and the tissue is indirectly displayed.

[0093] Contact Identification System FIG. 8 is a schematic block diagram of a system for identifying electrode-tissue contact in accordance with an embodiment of the present invention.

[0094] As shown in FIG. 8 , a system 800 for identifying contact between an electrode and tissue includes a collecting unit 810 , an impedance-frequency response coefficient determining unit 820 , and a contact state determining unit 830 .

[0095] The collection unit 810 is for collecting impedance between electrodes in the invasive device at different frequencies.

[0096] The body cavity invasive device includes a catheter, with the electrode located at the distal end of the catheter.

[0097] The catheter may be at least one of a basket type catheter, a balloon type catheter, a ring type catheter, a petal type catheter, a lattice type catheter, and / or a wire type catheter.

[0098] The electrodes referred to here include a working electrode (or in the case of therapy, called a therapy electrode) and a reference electrode. For example, the working electrode may be an ablation electrode. The collection unit 810 can thereby be used to collect impedances between the working electrode, the reference electrode, and between the working electrode and the reference electrode at different frequencies.

[0099] Different frequencies may be selected in response to different responses due to different tissue impedances to the frequencies.

[0100] The frequency range of the different frequencies is 500Hz to 100kHz.

[0101] In a preferred embodiment, the different frequencies are two different frequencies.

[0102] The impedance-frequency response coefficient determining unit 820 is for determining an impedance-frequency response coefficient between the electrodes based on the impedance between the electrodes collected by the collecting unit 810 .

[0103] The impedance-frequency response coefficient determining unit 820 may calculate the impedance-frequency response coefficient between the working electrode and the impedance-frequency response coefficient between the reference electrode according to the above equations (1) and (2), respectively.

[0104] The contact state determining unit 830 is for determining a contact state between the electrode and tissue in the body cavity based on the impedance-frequency response coefficient. Specifically, the contact state determining unit can be used to determine a contact state between the working electrode and tissue in the body cavity.

[0105] More specifically, the contact state determining unit 830 may calculate a contact index CI between the working electrodes i and j and the tissue according to the above equation (3).

[0106] The system 800 may further include a display unit (not shown) for indicating the contact state between the electrodes and the tissue in the body cavity with different colors.

[0107] It should be understood by those skilled in the art that the above-mentioned technical means, steps, and units can be arbitrarily combined to achieve the objectives of the present invention, unless the combination is logically or physically impossible.

[0108] Computer program, computer readable medium Furthermore, those skilled in the art should understand that the methods of the present disclosure can be realized as computer programs. As described with reference to the drawings, the methods of the above embodiments are executed by one or more programs including instructions that cause a computer or processor to execute the algorithms described with reference to the drawings. These programs may be stored in various non-transitory computer-readable media and provided to a computer or processor. Non-transitory computer-readable media include various tangible storage media. Non-transitory computer-readable media include, for example, magnetic recording media (e.g., floppy disks, magnetic tapes, and hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (compact disk read only memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., ROMs, PROMs (programmable ROMs), EPROMs (rewritable PROMs), flash ROMs, RAMs (random access memories, etc.)). Furthermore, these programs may be provided to a computer via various temporary computer-readable media. Transitory computer-readable media include, for example, electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable medium may be used to provide a program to a computer via a wired communication path, such as an electric wire or an optical fiber, or via a wireless communication path.

[0109] For example, according to one embodiment of the present disclosure, there may be provided an apparatus for identifying electrode-tissue contact, the apparatus including a processor and a memory having stored therein a computer program that, when executed by the processor, implements such a method for identifying electrode-tissue contact.

[0110] Therefore, according to the present disclosure there is also proposed a computer program or computer readable medium having stored thereon instructions executable by a processor which, when executed by the processor, causes the processor to perform a method for identifying contact between an electrode and tissue as described above.

[0111] Although each embodiment of the present disclosure has been described above, the above description is illustrative and not exhaustive, and the scope of the present invention is not limited to the above embodiment. It is obvious to those skilled in the art that many modifications and changes can be made without departing from the spirit and scope of the present invention. That is, various modifications and improvements in the form and details of the present invention are possible by those skilled in the art, but all of these are considered to be included in the protection scope of the present invention. The terms used in this specification are selected so as to best explain the principles and practices of each embodiment or improvements in the prior art, or to make each embodiment disclosed in this specification understandable to those skilled in the art.

Claims

1. 1. A method for identifying contact between an electrode and tissue, comprising: acquiring impedance between electrodes of the invasive device at different frequencies; determining an inter-electrode impedance-frequency response coefficient based on the collected inter-electrode impedance; and determining a contact condition between the electrode and tissue within the body cavity based on the impedance-frequency response coefficient.

2. 2. The method of claim 1, wherein the electrodes include a working electrode and a reference electrode, and collecting impedance between the electrodes at different frequencies includes collecting impedance between the working electrode, between the reference electrode, and between the working electrode and the reference electrode at different frequencies.

3. The method of claim 2 , wherein the working electrode comprises an ablation electrode.

4. 3. The method of claim 2, wherein determining contact between the electrode and tissue in the body cavity comprises determining contact between a working electrode and tissue in the body cavity.

5. 10. The method of claim 1, wherein the invasive device comprises a catheter, and the electrode is disposed at a distal end of the catheter.

6. 6. The method of claim 5, wherein the catheter comprises at least one of a basket-type catheter, a balloon-type catheter, a ring-type catheter, a petal-type catheter, a lattice-type catheter, and a wire-type catheter.

7. 2. The method of claim 1, wherein the different frequencies are selected in response to different responses due to different tissue impedances to the frequencies.

8. 2. The method of claim 1, wherein the different frequencies range from 500 Hz to 100 kHz.

9. 2. The method of claim 1, wherein the different frequencies are two different frequencies.

10. The electrodes include a working electrode and a reference electrode, wherein determining the impedance-frequency response coefficient between the electrodes includes calculating an impedance-frequency response coefficient between the working electrode and an impedance-frequency response coefficient between the reference electrode in accordance with Equation (1) and Equation (2), respectively; Impedance-frequency response coefficient Coef between working electrodes i and j ｉｊ teeth, [0010] And then, Impedance between reference electrodes m and n - frequency response coefficient Coef ｍｎ teeth, [0025] And then, wherein determining a contact state between the electrodes and tissue in the body cavity comprises calculating a contact index CI between working electrodes i and j and the tissue according to equation (3); [0030] In the above formulas (1), (2), and (3), [0045] is the impedance measured between working electrodes i and j at a first frequency Fr1, [0050] is the impedance measured between working electrodes i and j at a second frequency Fr2, [006] is the real part of the complex impedance measured between working electrodes i and j at a first frequency Fr1, [0070] is the real part of the complex impedance measured between working electrodes i and j at a second frequency Fr2, [0080] is the imaginary part of the complex impedance measured between working electrodes i and j at a first frequency Fr1, [0097] is the imaginary part of the complex impedance measured between working electrodes i and j at a second frequency Fr2, [0089] is the impedance measured between reference electrodes m and n at a first frequency Fr1, ##EQU00011## is the impedance measured between reference electrodes m and n at a second frequency Fr2, ##EQU00012## is the real part of the complex impedance measured between reference electrodes m and n at a first frequency Fr1, ##EQU00013## is the real part of the complex impedance measured between reference electrodes m and n at a second frequency Fr2, ##EQU00014## is the imaginary part of the complex impedance measured between reference electrodes m and n at a first frequency Fr1, ##EQU00015## represents the imaginary part of the complex impedance measured between reference electrodes m and n at a second frequency Fr2, and a ｉｊ , b ｉｊ , c ｉｊ , a ｍｎ , b ｍｎ , c ｍｎ is the weighting coefficient, Base ｉｊ is the base of the frequency response between working electrodes i and j, Base ｍｎ is the cardinal number of the frequency response between reference electrodes m and n, Dis ｉｊ is the distance between working electrodes i and j, Dis ｍｎ 10. The method of claim 9, wherein m is the spacing between reference electrodes m and n.

11. The Base ｉｊ Parameter and Base ｍｎ Parameter and Dis ｉｊ Parameter and Dis ｍｎ 11. The method of claim 10, wherein there is a correlation between the parameters.

12. The Base ｉｊ Parameter and Base ｍｎ The parameter is Dis ｉｊ Parameter and Dis ｍｎ 12. The method of claim 11, wherein the parameter is obtained by performing a higher order regression modeling analysis with the electrode width parameter and the electrode diameter parameter.

13. Weighting coefficient a ｉｊ , b ｉｊ , c ｉｊ , a ｍｎ , b ｍｎ , c ｍｎ The magnitude of reflects the weight of the impedance characteristics, capacitive reactance characteristics, and overall resistance and capacitance characteristics of the tissue or blood between the electrodes in the usage environment, where a ｉｊ +b ｉｊ +c ｉｊ = 1, a ｍｎ +b ｍｎ +c ｍｎ 11. The method of claim 10, wherein: =1.

14. 2. The method of claim 1, further comprising indicating a contact state between the electrode and tissue within the body cavity using different colors.

15. 1. A system for identifying electrode-tissue contact, comprising: a collection unit for collecting impedances between electrodes of the body cavity invasive device at different frequencies; an impedance-frequency response coefficient determining unit for determining an impedance-frequency response coefficient between the electrodes based on the collected impedance between the electrodes; a contact condition determining unit for determining a contact condition between the electrode and tissue within the body cavity based on the impedance-frequency response coefficient.

16. 16. The system of claim 15, wherein the electrodes include a working electrode and a reference electrode, and the collection unit is configured to collect impedance between the working electrode, between the reference electrode, and between the working electrode and the reference electrode at different frequencies.

17. The system of claim 16 , wherein the working electrode comprises an ablation electrode.

18. The system of claim 16 , wherein the contact condition determining unit is configured to determine a contact condition between a working electrode and tissue within a body cavity.

19. 16. The system of claim 15, wherein the invasive device includes a catheter, and the electrode is disposed at a distal end of the catheter.

20. 20. The system of claim 19, wherein the catheter comprises at least one of a basket-type catheter, a balloon-type catheter, a ring-type catheter, a petal-type catheter, a lattice-type catheter, and a wire-type catheter.

21. 16. The system of claim 15, wherein the different frequencies are selected in response to different responses due to different tissue impedances to the frequencies.

22. 16. The system of claim 15, wherein the different frequencies range from 500 Hz to 100 kHz.

23. 16. The system of claim 15, wherein the different frequencies are two different frequencies.

24. The electrodes include a working electrode and a reference electrode, Wherein the impedance-frequency response coefficient determination unit is configured to calculate an impedance-frequency response coefficient between the working electrode and an impedance-frequency response coefficient between the reference electrode according to Equation (1) and Equation (2), respectively; Impedance-frequency response coefficient Coef between working electrodes i and j ｉｊ teeth, ##EQU00016## And then, Impedance between reference electrodes m and n - frequency response coefficient Coef ｍｎ teeth, ##EQU00017## And then, wherein the contact state determination unit is configured to calculate a contact index CI between the working electrodes i and j and the tissue according to equation (3): [0018] In the above formulas (1), (2), and (3), [0019] is the impedance measured between working electrodes i and j at a first frequency Fr1, [0020] is the impedance measured between working electrodes i and j at a second frequency Fr2, ##EQU00021## is the real part of the complex impedance measured between working electrodes i and j at a first frequency Fr1, [0022] is the real part of the complex impedance measured between working electrodes i and j at a second frequency Fr2, [0023] is the imaginary part of the complex impedance measured between working electrodes i and j at a first frequency Fr1, [0024] is the imaginary part of the complex impedance measured between working electrodes i and j at a second frequency Fr2, [0025] is the impedance measured between reference electrodes m and n at a first frequency Fr1, [0026] is the impedance measured between reference electrodes m and n at a second frequency Fr2, [0027] is the real part of the complex impedance measured between reference electrodes m and n at a first frequency Fr1, [0028] is the real part of the complex impedance measured between reference electrodes m and n at a second frequency Fr2, [0029] is the imaginary part of the complex impedance measured between reference electrodes m and n at a first frequency Fr1, [0030] represents the imaginary part of the complex impedance measured between reference electrodes m and n at a second frequency Fr2, and a ｉｊ , b ｉｊ , c ｉｊ , a ｍｎ , b ｍｎ , c ｍｎ is the weighting coefficient, Base ｉｊ is the base of the frequency response between working electrodes i and j, Base ｍｎ is the cardinal number of the frequency response between reference electrodes m and n, Dis ｉｊ is the distance between working electrodes i and j, Dis ｍｎ 24. The system of claim 23, wherein: is the spacing between reference electrodes m and n.

25. The Base ｉｊ Parameter and Base ｍｎ Parameter and Dis ｉｊ Parameter and Dis ｍｎ 25. The system of claim 24, wherein there is a correlation between the parameters.

26. The Base ｉｊ Parameter and Base ｍｎ The parameter is Dis ｉｊ Parameter and Dis ｍｎ 26. The system of claim 25, wherein the parameter is obtained by performing a higher order regression modeling analysis with the electrode width parameter and the electrode diameter parameter.

27. Weighting coefficient a ｉｊ , b ｉｊ , c ｉｊ , a ｍｎ , b ｍｎ , c ｍｎ The magnitude of reflects the weight of the impedance characteristics, capacitive reactance characteristics, and overall resistance and capacitance characteristics of the tissue or blood between the electrodes in the usage environment, where a ｉｊ +b ｉｊ +c ｉｊ = 1, a ｍｎ +b ｍｎ +c ｍｎ 25. The system of claim 24, wherein: =1.

28. 16. The system according to claim 15, further comprising a display unit for displaying a contact state between the electrode and tissue in the body cavity by using different colors.

29. A computer readable medium having stored thereon instructions executable by a processor that, when executed by the processor, cause the processor to perform the method for identifying electrode-tissue contact of claim 1.

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